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Sample records for atmospheric electrons due

  1. Greenhouse effect due to atmospheric nitrous oxide

    Science.gov (United States)

    Yung, Y. L.; Wang, W. C.; Lacis, A. A.

    1976-01-01

    The greenhouse effect due to nitrous oxide in the present atmosphere is about 0.8 K. Increase in atmospheric N2O due to perturbation of the nitrogen cycle by man may lead to an increase in surface temperature as large as 0.5 K by 2025, or 1.0 K by 2100. Other climatic effects of N2O are briefly discussed.

  2. Catalysts under Controlled Atmospheres in the Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Wagner, Jakob Birkedal

    2014-01-01

    microscope, and since its invention by Ernst Ruska, the idea of imaging samples under gaseous atmospheres was envisioned. However, microscopes have traditionally been operated in high vacuum due to sensitive electron sources, sample contamination, and electron scattering off gas molecules resulting in loss...

  3. Study of Compton Broadening Due to Electron-Photon Scattering

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao, M.

    2010-06-01

    Full Text Available We have investigated the effects of Compton broadening due to electron-photon scattering in hot stellar atmospheres. A purely electron-photon scattering media is assumed to have plane parallel geometry with an input radiation field localized on one side of the slab. The method is based on the discrete space theory of radiative transfer for the intensity of emitted radiation.The solution is developed to study the importance of scattering of radiation by free electrons in high temperature stellar atmospheres which produces a brodening and shift in spectral lines because of the Compton effect and the Doppler effect arising from mass and thermal motions of scattering electrons.It is noticed that the Comptonized spectrum depends on three parameters: the optical depth of the medium, the temperature of the thermal electrons and the viewing angle.We also showed that the Compton effect produces red shift and asymmetry in the line. These two effects increase as the optical depth increases. It is also noticed that the emergent specific intensities become completely asymmetric for higher optical depths.

  4. Electron heating in atmospheric pressure glow discharges

    Science.gov (United States)

    Stark, Robert H.; Schoenbach, Karl H.

    2001-04-01

    The application of nanosecond voltage pulses to weakly ionized atmospheric pressure plasmas allows heating the electrons without considerably increasing the gas temperature, provided that the duration of the pulses is less than the critical time for the development of glow-to-arc transitions. The shift in the electron energy distribution towards higher energies causes a temporary increase in the ionization rate, and consequently a strong rise in electron density. This increase in electron density is reflected in an increased decay time of the plasma after the pulse application. Experiments in atmospheric pressure air glow discharges with gas temperatures of approximately 2000 K have been performed to explore the electron heating effect. Measurements of the temporal development of the voltage across the discharge and the optical emission in the visible after applying a 10 ns high voltage pulse to a weakly ionized steady state plasma demonstrated increasing plasma decay times from tens of nanoseconds to microseconds when the pulsed electric field was raised from 10 to 40 kV/cm. Temporally resolved photographs of the discharge have shown that the plasma column expands during this process. The nonlinear electron heating effect can be used to reduce the power consumption in a repetitively operated air plasma considerably compared to a dc plasma operation. Besides allowing power reduction, pulsed electron heating also has the potential to enhance plasma processes, which require elevated electron energies, such as excimer generation for ultraviolet lamps.

  5. Alignment of atmospheric mineral dust due to electric field

    Directory of Open Access Journals (Sweden)

    Z. Ulanowski

    2007-09-01

    Full Text Available Optical polarimetry observations on La Palma, Canary Islands, during a Saharan dust episode show dichroic extinction consistent with the presence of vertically aligned particles in the atmosphere. Modelling of the extinction together with particle orientation indicates that the alignment could have been due to an electric field of the order of 2 kV/m. Two alternative mechanisms for the origin of the field are examined: the effect of reduced atmospheric conductivity and charging of the dust layer, the latter effect being a more likely candidate. It is concluded that partial alignment may be a common feature of Saharan dust layers. The modelling also indicates that the alignment can significantly alter dust optical depth. This "Venetian blind effect" may have decreased optical thickness in the vertical direction by as much as 10% for the case reported here.

  6. Alignment of atmospheric mineral dust due to electric field

    Science.gov (United States)

    Ulanowski, Z.; Bailey, J.; Lucas, P. W.; Hough, J. H.; Hirst, E.

    2007-12-01

    Optical polarimetry observations on La Palma, Canary Islands, during a Saharan dust episode show dichroic extinction indicating the presence of vertically aligned particles in the atmosphere. Modelling of the extinction together with particle orientation indicates that the alignment could have been due to an electric field of the order of 2 kV/m. Two alternative mechanisms for the origin of the field are examined: the effect of reduced atmospheric conductivity and charging of the dust layer, the latter effect being a more likely candidate. It is concluded that partial alignment may be a common feature of Saharan dust layers. The modelling indicates that the alignment can significantly alter dust optical depth. This "Venetian blind effect" may have decreased optical thickness in the vertical direction by as much as 10% for the case reported here. It is also possible that the alignment and the electric field modify dust transport.

  7. Atmospheric Deposition of Soluble Organic Nitrogen due to Biomass Burning

    Science.gov (United States)

    Ito, A.; Lin, G.; Penner, J. E.

    2014-12-01

    Atmospheric deposition of reactive nitrogen (N) species from large fires may contribute to enrichment of nutrients in aquatic ecosystems. Here we use an atmospheric chemistry transport model to investigate the supply of soluble organic nitrogen (ON) from open biomass burning to the ocean. The model results show that the annual deposition rate of soluble ON to the oceans is increased globally by 13% with the increase being particularly notable over the coastal water downwind from the source regions. The estimated deposition of soluble ON due to haze events from the secondary formation is more than half of that from the primary sources. We examine the secondary formation of particulate C-N compounds (e.g., imidazole) from the reactions of glyoxal and methylglyoxal with atmospheric ammonium in wet aerosols and upon cloud evaporation. These ON sources result in a significant contribution to the open ocean, suggesting that atmospheric processing in aqueous phase may have a large effect. We compare the soluble ON concentration in aerosols with and without open biomass burning as a case study in Singapore. The model results demonstrate that the soluble ON concentration in aerosols is episodically enriched during the fire events, compared to the without smoke simulations. However, the model results show that the daily soluble ON concentration can be also enhanced in the without smoke simulations during the same period, compared to the monthly averages. This indicates that care should be taken when using in-situ observations to constrain the soluble ON source strength from biomass burning. More accurate quantification of the soluble ON burdens with no smoke sources is therefore needed to assess the effect of biomass burning on bioavailable ON input to the oceans.

  8. Radiation Belt Electron Dynamics: Modeling Atmospheric Losses

    Science.gov (United States)

    Selesnick, R. S.

    2003-01-01

    The first year of work on this project has been completed. This report provides a summary of the progress made and the plan for the coming year. Also included with this report is a preprint of an article that was accepted for publication in Journal of Geophysical Research and describes in detail most of the results from the first year of effort. The goal for the first year was to develop a radiation belt electron model for fitting to data from the SAMPEX and Polar satellites that would provide an empirical description of the electron losses into the upper atmosphere. This was largely accomplished according to the original plan (with one exception being that, for reasons described below, the inclusion of the loss cone electrons in the model was deferred). The main concerns at the start were to accurately represent the balance between pitch angle diffusion and eastward drift that determines the dominant features of the low altitude data, and then to accurately convert the model into simulated data based on the characteristics of the particular electron detectors. Considerable effort was devoted to achieving these ends. Once the model was providing accurate results it was applied to data sets selected from appropriate periods in 1997, 1998, and 1999. For each interval of -30 to 60 days, the model parameters were calculated daily, thus providing good short and long term temporal resolution, and for a range of radial locations from L = 2.7 to 3.9. .

  9. Jet formation in solar atmosphere due to magnetic reconnection

    CERN Document Server

    González-Avilés, J J; Fedun, V

    2016-01-01

    Using numerical simulations, we show that jets with features of type II spicules and cold coronal jets corresponding to temperatures $10^{4}$ K can be formed due to magnetic reconnection in a scenario in presence of magnetic resistivity. For this we model the low chromosphere-corona region using the C7 equilibrium solar atmosphere model and assuming Resistive MHD rules the dynamics of the plasma. The magnetic filed configurations we analyze correspond to two neighboring loops with opposite polarity. The separation of the loops' feet determines the thickness of a current sheet that triggers a magnetic reconnection process, and the further formation of a high speed and sharp structure. We analyze the cases where the magnetic filed strength of the two loops is equal and different. In the first case, with a symmetric configuration the spicules raise vertically whereas in an asymmetric configuration the structure shows an inclination. With a number of simulations carried out under a 2.5D approach, we explore vario...

  10. Atmosphere-Ionosphere Coupling due to Atmospheric Tides (Julius Bartels Medal Lecture)

    Science.gov (United States)

    Forbes, Jeffrey M.

    2016-04-01

    Within the last decade, a new realization has arrived on the scene of ionosphere-thermosphere (IT) science: terrestrial weather significantly influences space weather. The aspect of space weather referred to here consists of electron density variability that translates to uncertainties in navigation and communications systems, and neutral density variability that translates to uncertainties in orbital and reentry predictions. In the present context "terrestrial weather" primarily refers to the meteorological conditions that determine the spatial-temporal distribution of tropospheric water vapor and latent heating associated with tropical convection, and the middle atmosphere disturbances associated with sudden stratosphere warmings. The net effect of these processes is a spatially- and temporally-evolving spectrum of waves (gravity waves, tides, planetary waves, Kelvin waves) that grows in amplitude with height and enters the IT system near ~100 km. Some members of the wave spectrum penetrate all the way to the base of the exosphere (ca. 500 km). Along the way, nonlinear interactions between different wave components occur, modifying the interacting waves and giving rise to secondary waves. Finally, the IT wind perturbations carried by the waves can redistribute ionospheric plasma, either through the electric fields generated via the dynamo mechanism between 100 and 150 km, or directly by moving plasma along magnetic field lines at higher levels. Additionally, the signatures of wave-driven dynamo currents are reflected in magnetic perturbations observed at the ground. This is how terrestrial atmospheric variability, through the spectrum of vertically- propagating waves that it produces, can effectively drive IT space weather. The primary objective of this Julius Bartels Lecture is to provide an overview of the global observational evidence for the IT consequences of these upward-propagating waves. In honor of Julius Bartels, who performed much research (including

  11. The electron energy loss rate due to radiative recombination

    Science.gov (United States)

    Mao, Junjie; Kaastra, Jelle; Badnell, N. R.

    2017-02-01

    Context. For photoionized plasmas, electron energy loss rates due to radiative recombination (RR) are required for thermal equilibrium calculations, which assume a local balance between the energy gain and loss. While many calculations of total and/or partial RR rates are available from the literature, specific calculations of associated RR electron energy loss rates are lacking. Aims: Here we focus on electron energy loss rates due to radiative recombination of H-like to Ne-like ions for all the elements up to and including zinc (Z = 30), over a wide temperature range. Methods: We used the AUTOSTRUCTURE code to calculate the level-resolved photoionization cross section and modify the ADASRR code so that we can simultaneously obtain level-resolved RR rate coefficients and associated RR electron energy loss rate coefficients. We compared the total RR rates and electron energy loss rates of H i and He i with those found in the literature. Furthermore, we utilized and parameterized the weighted electron energy loss factors (dimensionless) to characterize total electron energy loss rates due to RR. Results: The RR electron energy loss data are archived according to the Atomic Data and Analysis Structure (ADAS) data class adf48. The RR electron energy loss data are also incorporated into the SPEX code for detailed modeling of photoionized plamsas. Full Tables 1 and 2 are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A10

  12. Jet Formation in Solar Atmosphere due to Magnetic Reconnection

    Science.gov (United States)

    González-Avilés, J. J.; Guzmán, F. S.; Fedun, V.

    2017-02-01

    Using numerical simulations, we show that jets with features of type II spicules and cool coronal jets corresponding to temperatures of 104 K can be formed as a result of magnetic reconnection in a scenario with magnetic resistivity. For this, we model the low chromosphere–corona region using the C7 equilibrium solar atmosphere model, assuming that resistive MHD rules the dynamics of the plasma. The magnetic field configurations we analyze correspond to two neighboring loops with opposite polarity. The formation of a high-speed and sharp structure depends on the separation of the loops’ feet. We analyze the cases where the magnetic field strength of the two loops is equal and different. In the first case, with a symmetric configuration the jets rise vertically, whereas in an asymmetric configuration the structure shows an inclination. With a number of simulations carried out under a 2.5D approach, we explore various properties of the excited jets, namely, inclination, lifetime, and velocity. The parameter space involves a magnetic field strength between 20 and 40 G, and the resistivity is assumed to be uniform with a constant value of the order {10}-2{{Ω }}\\cdot m.

  13. Atmosphere to Electrons: Enabling the Wind Plant of Tomorrow

    Energy Technology Data Exchange (ETDEWEB)

    Office of Energy Efficiency and Renewable Energy

    2015-11-01

    The U.S. Department of Energy’s Atmosphere to Electrons research initiative is focused on improving the performance and reliability of wind plants by establishing an unprecedented understanding of how the Earth’s atmosphere interacts with the wind plants and developing innovative technologies to maximize energy extraction from the wind.

  14. Wet precipitation scavenging of soluble atmospheric trace gases due to chemical absorption in inhomogeneous atmosphere

    Science.gov (United States)

    Elperin, Tov; Fominykh, Andrew; Krasovitov, Boris

    2017-02-01

    We analyze the effects of irreversible chemical reactions of the first and higher orders and aqueous-phase dissociation reactions on the rate of trace gas scavenging by rain in the atmosphere with non-uniform concentration and temperature. We employ an one-dimensional model of precipitation scavenging of chemically active soluble gaseous pollutants that is valid for small gradients of temperature and concentration in the atmosphere. It is demonstrated that transient altitudinal distribution of concentration under the influence of rain is determined by the partial hyperbolic differential equation of the first order. Scavenging coefficients are calculated for wet removal of chlorine, nitrogen dioxide and sulfur dioxide for the exponential and linear initial altitudinal distributions of trace gases concentration in the atmosphere and linear and uniform altitudinal temperature distributions. Theoretical predictions of the dependence of the magnitude of the scavenging coefficient on rain intensity for sulfur dioxide are in a good agreement with the available atmospheric measurements.

  15. Changes in the Earth's Spin Rotation due to the Atmospheric Effects and Reduction in Glaciers

    Science.gov (United States)

    Na, Sung-Ho; Cho, Jungho; Kim, Tu-Hwan; Seo, Kiweon; Youm, Kookhyoun; Yoo, Sung-Moon; Choi, Byungkyu; Yoon, Hasu

    2016-12-01

    The atmosphere strongly affects the Earth's spin rotation in wide range of timescale from daily to annual. Its dominant role in the seasonal perturbations of both the pole position and spinning rate of the Earth is once again confirmed by a comparison of two recent data sets; i) the Earth orientation parameter and ii) the global atmospheric state. The atmospheric semi-diurnal tide has been known to be a source of the Earth's spin acceleration, and its magnitude is re-estimated by using an enhanced formulation and an up-dated empirical atmospheric S2 tide model. During the last twenty years, an unusual eastward drift of the Earth's pole has been observed. The change in the Earth's inertia tensor due to glacier mass redistribution is directly assessed, and the recent eastward movement of the pole is ascribed to this change. Furthermore, the associated changes in the length of day and UT1 are estimated.

  16. Generation of subnanosecond electron beams in air at atmospheric pressure

    Science.gov (United States)

    Kostyrya, I. D.; Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.; Lomaev, M. I.; Rybka, D. V.

    2009-11-01

    Optimum conditions for the generation of runaway electron beams with maximum current amplitudes and densities in nanosecond pulsed discharges in air at atmospheric pressure are determined. A supershort avalanche electron beam (SAEB) with a current amplitude of ˜30 A, a current density of ˜20 A/cm2, and a pulse full width at half maximum (FWHM) of ˜100 ps has been observed behind the output foil of an air-filled diode. It is shown that the position of the SAEB current maximum relative to the voltage pulse front exhibits a time shift that varies when the small-size collector is moved over the foil surface.

  17. Electron spectroscopy of selected atmospheric molecules and hydrocarbons

    Science.gov (United States)

    Davies, Julia Ann

    The thesis presents experimental results obtained by electron impact energy-loss spectroscopy. Differential oscillator strengths (DOS) of selected atmospheric molecules and hydrocarbons and vibrational excitation cross sections of ozone are measured. A critical comparison with earlier experiments and theory (where it exists) is made. The thesis is arranged in seven chapters. The first discusses molecular structure, spectroscopy and electron-molecule scattering as is relevant to the scope of this thesis. The next two chapters describe the experimental apparatus used. A high resolution electron spectrometer produces an electron beam (˜10 nA) incident upon the molecular target. Scattered electrons of selected energy-loss and scattering angle are detected by the spectrometer providing a total apparatus resolution of ˜50 meV. The vacuum system, gas inlet system and power supplies are also discussed. Chapters 4, 5 and 6 contain the main results obtained during postgraduate studies. DOS of selected atmospheric molecules (O2, N2, N2O, CO and CO2) are presented and critically compared with previous optical and synchrotron studies. Good agreement between results validates the experimental apparatus and techniques used in this work. A detailed study of the DOS of small alkanes (CH4, C2H6, C3H8 and C4H10) and small alkenes (C2H4, C3H6 and C4H8) shows similarities and trends in these series. DOS of ozone, O3, are also measured and the vibrational excitation of ozone is investigated as a function of scattering angle (40° ≤ theta ≤ 120°) and inccident energy (3 eVatmospheric molecules, are also presented.

  18. Extreme atmospheric electron densities created by extensive air showers

    Science.gov (United States)

    Rutjes, Casper; Camporeale, Enrico; Ebert, Ute; Buitink, Stijn; Scholten, Olaf; Trinh, Gia

    2016-04-01

    A sufficient density of free electrons and strong electric fields are the basic requirements to start any electrical discharge. In the context of thunderstorm discharges it has become clear that in addition droplets and or ice particles are required to enhance the electric field to values above breakdown. In our recent study [1] we have shown that these three ingredients have to interplay to allow for lightning inception, triggered by an extensive air shower event. The extensive air showers are a very stochastic natural phenomenon, creating highly coherent bursts of extreme electron density in our atmosphere. Predicting these electron density bursts accurately one has to take the uncertainty of the input variables into account. To this end we use uncertainty quantification methods, like in [2], to post-process our detailed Monte Carlo extensive air shower simulations, done with the CORSIKA [3] software package, which provides an efficient and elegant way to determine the distribution of the atmospheric electron density enhancements. We will present the latest results. [1] Dubinova, A., Rutjes, C., Ebert, E., Buitink, S., Scholten, O., and Trinh, G. T. N. "Prediction of Lightning Inception by Large Ice Particles and Extensive Air Showers." PRL 115 015002 (2015) [2] G.J.A. Loeven, J.A.S. Witteveen, H. Bijl, Probabilistic collocation: an efficient nonintrusive approach for arbitrarily distributed parametric uncertainties, 45th AIAA Aerospace Sciences Meeting, Reno, Nevada, 2007, AIAA-2007-317 [3] Heck, Dieter, et al. CORSIKA: A Monte Carlo code to simulate extensive air showers. No. FZKA-6019. 1998.

  19. Measurement of microwave radiation from electron beam in the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, I.S.; Akimune, H. [Faculty of Science and Engineering, Konan University, Kobe 658-8501 (Japan); Fukushima, M.; Ikeda, D. [Institute of Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Inome, Y. [Faculty of Science and Engineering, Konan University, Kobe 658-8501 (Japan); Matthews, J.N. [University of Utah, Salt Lake City, UT 4112-0830 (United States); Ogio, S. [Graduate School of Science, Osaka City University, Osaka 558-8585 (Japan); Sagawa, H. [Institute of Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Sako, T. [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601 (Japan); Shibata, T. [High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan); Yamamoto, T., E-mail: tokonatu@konan-u.ac.jp [Faculty of Science and Engineering, Konan University, Kobe 658-8501 (Japan)

    2016-02-21

    We report the use of an electron light source (ELS) located at the Telescope Array Observatory in Utah, USA, to measure the isotropic microwave radiation from air showers. To simulate extensive air showers, the ELS emits an electron beam into the atmosphere and a parabola antenna system for the satellite communication is used to measure the microwave radiation from the electron beam. Based on this measurement, an upper limit on the intensity of a 12.5 GHz microwave radiation at 0.5 m from a 10{sup 18} eV air shower was estimated to be 3.96×10{sup −16} W m{sup −2} Hz{sup −1} with a 95% confidence level.

  20. Nonlinear charge transport in bipolar semiconductors due to electron heating

    Energy Technology Data Exchange (ETDEWEB)

    Molina-Valdovinos, S., E-mail: sergiom@fisica.uaz.edu.mx [Universidad Autónoma de Zacatecas, Unidad Académica de Física, Calzada Solidaridad esq. Paseo, La Bufa s/n, CP 98060, Zacatecas, Zac, México (Mexico); Gurevich, Yu.G. [Centro de Investigación y de Estudios Avanzados del IPN, Departamento de Física, Av. IPN 2508, México D.F., CP 07360, México (Mexico)

    2016-05-27

    It is known that when strong electric field is applied to a semiconductor sample, the current voltage characteristic deviates from the linear response. In this letter, we propose a new point of view of nonlinearity in semiconductors which is associated with the electron temperature dependence on the recombination rate. The heating of the charge carriers breaks the balance between generation and recombination, giving rise to nonequilibrium charge carriers concentration and nonlinearity. - Highlights: • A new mechanism of nonlinearity of current-voltage characteristic (CVC) is proposed. • The hot electron temperature violates the equilibrium between electrons and holes. • This violation gives rise to nonequilibrium concentration of electrons and holes. • This leads to nonlinear CVC (along with the heating nonlinearity).

  1. Mechanical energy input to the world oceans due to atmospheric loading

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; QIAN Chengchun; HUANG Ruixin

    2006-01-01

    Mechanical energy input to the oceans is one of the most important factors controlling the oceanic general circulation. The atmosphere transports mechanical energy to the oceans primarily through wind stress, plus changes of the sea level pressure (the so-called atmospheric loading). The rate of mechanical energy transfer into the ocean due to atmospheric loading is calculated, based on TOPEX/POSEIDON data over ten-year period (1993-2002). The rate of total energy input for the world oceans is estimated at 0.04TW (1TW=1012Watt), and most of this energy input is concentrated in the Southern Oceans and the Storm Tracks in the Northern Hemisphere. This energy input varied greatly with time, and the amplitude of the interannual variability over the past ten years is about 15%.

  2. Energetic electron precipitation into the middle atmosphere -- Constructing the loss cone fluxes from MEPED POES

    Science.gov (United States)

    Nesse Tyssøy, H.; Sandanger, M. I.; Ødegaard, L.-K. G.; Stadsnes, J.; Aasnes, A.; Zawedde, A. E.

    2016-06-01

    The impact of energetic electron precipitation (EEP) on the chemistry of the middle atmosphere (50-90 km) is still an outstanding question as accurate quantification of EEP is lacking due to instrumental challenges and insufficient pitch angle coverage of current particle detectors. The Medium Energy Proton and Electron Detectors (MEPED) instrument on board the NOAA/Polar Orbiting Environmental Satellites (POES) and MetOp spacecraft has two sets of electron and proton telescopes pointing close to zenith (0°) and in the horizontal plane (90°). Using measurements from either the 0° or 90° telescope will underestimate or overestimate the bounce loss cone flux, respectively, as the energetic electron fluxes are often strongly anisotropic with decreasing fluxes toward the center of the loss cone. By combining the measurements from both telescopes with electron pitch angle distributions from theory of wave-particle interactions in the magnetosphere, a complete bounce loss cone flux is constructed for each of the electron energy channels >50 keV, >100 keV, and >300 keV. We apply a correction method to remove proton contamination in the electron counts. We also account for the relativistic (>1000 keV) electrons contaminating the proton detector at subauroral latitudes. This gives us full range coverage of electron energies that will be deposited in the middle atmosphere. Finally, we demonstrate the method's applicability on strongly anisotropic pitch angle distributions during a weak geomagnetic storm in February 2008. We compare the electron fluxes and subsequent energy deposition estimates to OH observations from the Microwave Limb Sounder on the Aura satellite substantiating that the estimated fluxes are representative for the true precipitating fluxes impacting the atmosphere.

  3. Fast Magnetic Reconnection Due to Anisotropic Electron Pressure

    CERN Document Server

    Cassak, P A; Fermo, R L; Beidler, M T; Shay, M A; Swisdak, M; Drake, J F; Karimabadi, H

    2015-01-01

    A new regime of fast magnetic reconnection with an out-of-plane (guide) magnetic field is reported in which the key role is played by an electron pressure anisotropy described by the Chew-Goldberger-Low gyrotropic equations of state in the generalized Ohm's law, which even dominates the Hall term. A description of the physical cause of this behavior is provided and two-dimensional fluid simulations are used to confirm the results. The electron pressure anisotropy causes the out-of-plane magnetic field to develop a quadrupole structure of opposite polarity to the Hall magnetic field and gives rise to dispersive waves. In addition to being important for understanding what causes reconnection to be fast, this mechanism should dominate in plasmas with low plasma beta and a high in-plane plasma beta with electron temperature comparable to or larger than ion temperature, so it could be relevant in the solar wind and some tokamaks.

  4. Atmospheric energy input and ionization by energetic electrons during the geomagnetic storm of 8-9 November 1991

    Science.gov (United States)

    Chenette, D. L.; Datlowe, D. W.; Robinson, R. M.; Schumaker, T. L.; Vondrak, R. R.; Winningham, J. D.

    1993-01-01

    The Atmospheric X-ray Imaging Spectrometer (AXIS) of the Particle Environment Monitor investigation aboard the Upper Atmosphere Research Satellite monitors energy input to the upper atmosphere due to energetic electrons. Analysis of the AXIS data from the major geomagnetic storm of 8-9 November 1991 is presented. During the November storm, electrons above a few keV flowing into a substantially expanded auroral zone provided the bulk of the ionizing power to the upper atmosphere. At the peak of the disturbance the total AXIS-observed power reached 40 GW. On 9 November the whole day average atmospheric ionization rate in the auroral zone at 80 km altitude exceeded the rate due to solar UV and solar X-rays by a factor of over 10 to 100.

  5. On a source of electron impact ionization in Io's upstream atmosphere

    Science.gov (United States)

    Shaposhnikov, V. E.; Zaitsev, V. V.; Rucker, H. O.; Litvinenko, G. V.; Konovalenko, A. A.

    2013-09-01

    A mechanism for the ionization of Io's atmosphere due to the moon's motion through the Jovian magnetic field is considered. Attention is paid to the important role of charge separation in the upstream part of Io's ionosphere and accumulation of electrons and positive ions on the low and top ionospheric boundaries which results in (a) the creation of longitudinal component (with respect to the Jovian magnetic field lines) of polarization electric field, (b) the driving of Bounemann plasma turbulence, and (c) the heating of electrons and the ionization of neutrals. Estimations show that the proposed mechanism can essentially heat the electrons and increase the electron density. The increase with the plasma density and the electron temperature can result in an ionospheric plasma distribution and overcomes the difficulty with generation of the most bright part of UV emission of the Io's equatorial spots.

  6. Energetic electron precipitation into the middle atmosphere - Constructing the loss cone fluxes from MEPED POES

    CERN Document Server

    Tyssøy, H Nesse; Ødegaard, L -K G; Stadsnes, J; Aasnes, A; Zawedde, A E

    2016-01-01

    The impact of energetic electron precipitation (EEP) on the chemistry of the middle atmosphere (50-90 km) is still an outstanding question as accurate quantification of EEP is lacking due to instrumental challenges and insufficient pitch angle coverage of current particle detectors. The Medium Energy Proton and Electron Detectors (MEPED) instrument on board the NOAA/Polar Orbiting Environmental Satellites(POES) and MetOp spacecraft has two sets of electron and proton telescopes pointing close to zenith ($0\\,^{\\circ}$) and in the horizontal plane ($90\\,^{\\circ}$). Using measurements from either the $0\\,^{\\circ}$ or $90\\,^{\\circ}$ telescope will underestimate or overestimate the bounce loss cone flux, respectively, as the energetic electron fluxes are often strongly anisotropic with decreasing fluxes toward the center of the loss cone. By combining the measurements from both telescopes with electron pitch angle distributions from theory of wave-particle interactions in the magnetosphere, a complete bounce loss ...

  7. Response of the global climate to changes in atmospheric chemical composition due to fossil fuel burning

    Science.gov (United States)

    Hameed, S.; Cess, R. D.; Hogan, J. S.

    1980-01-01

    Recent modeling of atmospheric chemical processes (Logan et al, 1978; Hameed et al, 1979) suggests that tropospheric ozone and methane might significantly increase in the future as the result of increasing anthropogenic emissions of CO, NO(x), and CH4 due to fossil fuel burning. Since O3 and CH4 are both greenhouse gases, increases in their concentrations could augment global warming due to larger future amounts of atmospheric CO2. To test the possible climatic impact of changes in tropospheric chemical composition, a zonal energy-balance climate model has been combined with a vertically averaged tropospheric chemical model. The latter model includes all relevant chemical reactions which affect species derived from H2O, O2, CH4, and NO(x). The climate model correspondingly incorporates changes in the infrared heating of the surface-troposphere system resulting from chemically induced changes in tropospheric ozone and methane. This coupled climate-chemical model indicates that global climate is sensitive to changes in emissions of CO, NO(x) and CH4, and that future increases in these emissions could augment global warming due to increasing atmospheric CO2.

  8. Global atmospheric energy deposition by energetic electrons - Quantitative spatial and temporal characteristics inferred from the Atmospheric X-ray Imaging Spectrometer (PEM/AXIS) on UARS

    Science.gov (United States)

    Chenette, D. L.; Datlowe, D. W.; Robinson, R. M.; Schumaker, T. L.; Vondrak, R. R.; Frahm, R. A.; Sharber, J. R.; Winningham, J. D.

    1993-01-01

    The primary purpose of PEM/AXIS is to provide a global monitor of the energy input to the upper atmosphere due to energetic electrons. The design, development, and calibration of AXIS are described and an assessment of its excellent on-orbit performance is presented. The unique capabilities of X-ray imaging spectrometers to monitor the global patterns of electron energy deposition in the atmosphere are shown through an analysis of some specific cases during the first year of the UARS mission.

  9. Electron densities and alkali atoms in exoplanet atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Lavvas, P. [GSMA, Université de Reims Champagne Ardenne, CNRS UMR 7331, Reims, 51687 France (France); Koskinen, T.; Yelle, R. V., E-mail: panayotis.lavvas@univ-reims.fr [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85719 (United States)

    2014-11-20

    We describe a detailed study on the properties of alkali atoms in extrasolar giant planets, and specifically focus on their role in generating the atmospheric free electron densities, as well as their impact on the transit depth observations. We focus our study on the case of HD 209458b, and we show that photoionization produces a large electron density in the middle atmosphere that is about two orders of magnitude larger than the density anticipated from thermal ionization. Our purely photochemical calculations, though, result in a much larger transit depth for K than observed for this planet. This result does not change even if the roles of molecular chemistry and excited state chemistry are considered for the alkali atoms. In contrast, the model results for the case of exoplanet XO-2b are in good agreement with the available observations. Given these results we discuss other possible scenarios, such as changes in the elemental abundances, changes in the temperature profiles, and the possible presence of clouds, which could potentially explain the observed HD 209458b alkali properties. We find that most of these scenarios cannot explain the observations, with the exception of a heterogeneous source (i.e., clouds or aerosols) under specific conditions, but we also note the discrepancies among the available observations.

  10. Atmospheric electron neutrinos in the MINOS far detector

    Energy Technology Data Exchange (ETDEWEB)

    Speakman, Benjamin Phillip [Univ. of Minnesota, Minneapolis, MN (United States)

    2007-01-01

    Neutrinos produced as a result of cosmic-ray interactions in the earth's atmosphere offer a powerful probe into the nature of this three-membered family of low-mass, weakly-interacting particles. Ten years ago, the Super-Kamiokande Experiment has confirmed earlier indications that neutrinos undergo lepton-flavor oscillations during propagation, proving that they are massive contrary to the previous Standard Model assumptions. The Soudan Underground Laboratory, located in northern Minnesota, was host to the Soudan2 Experiment, which has made important contributions to atmospheric neutrino research. This same lab has more recently been host to the MINOS far detector, a neutrino detector which serves as the downstream element of an accelerator-based long-baseline neutrino-oscillation experiment. This thesis has examined 418.5 live days of atmospheric neutrino data (fiducial exposure of 4.18 kton-years) collected in the MINOS far detector prior to the activation of the NuMI neutrino beam, with a specific emphasis on the investigation of electron-type neutrino interactions. Atmospheric neutrino interaction candidates have been selected and separated into showering or track-like events. The showering sample consists of 89 observed events, while the track-like sample consists of 112 observed events. Based on the Bartol atmospheric neutrino flux model of Barr et al. plus a Monte Carlo (MC) simulation of interactions in the MINOS detector, the expected yields of showering and track-like events in the absence of neutrino oscillations are 88.0 ± 1.0 and 149.1 ± 1.0 respectively (where the uncertainties reflect only the limited MC statistics). Major systematic uncertainties, especially those associated with the flux model, are cancelled by forming a double ratio of these observed and expected yields: R$data\\atop{trk/shw}$/R$MC\\atop{trk/shw}$ = 0.74$+0.12\\atop{-1.0}$(stat.) ± 0.04 (syst.) This double ratio should be equal to unity in the absence of oscillations, and

  11. Polarization of thermal bremsstrahlung emission due to electron pressure anisotropy

    CERN Document Server

    Komarov, S; Churazov, E; Schekochihin, A

    2016-01-01

    Astrophysical plasmas are typically magnetized, with the Larmor radii of the charged particles many orders of magnitude smaller than their collisional mean free paths. The fundamental properties of such plasmas, e.g., conduction and viscosity, may depend on the instabilities driven by the anisotropy of the particle distribution functions and operating at scales comparable to the Larmor scales. We discuss a possibility that the pressure anisotropy of thermal electrons could produce polarization of thermal bremsstrahlung emission. In particular, we consider coherent large-scale motions in galaxy clusters to estimate the level of anisotropy driven by stretching of the magnetic-field lines by plasma flow and by heat fluxes associated with thermal gradients. Our estimate of the degree of polarization is $\\sim 0.1 \\%$ at energies $\\gtrsim kT$. While this value is too low for the forthcoming generation of X-ray polarimeters, it is potentially an important proxy for the processes taking place at extremely small scale...

  12. Electronic Data Discovery: Integrating Due Process into Cyber Forensic Practice

    Directory of Open Access Journals (Sweden)

    John W. Bagby

    2006-03-01

    Full Text Available Most organizations and government agencies regularly become engaged in litigation with suppliers, customers, clients, employees, competitors, shareholders, prosecutors or regulatory agencies that nearly assures the need to organize, retain, find and produce business records and correspondence, e-mails, accounting records or other data relevant to disputed issues. This article discusses some high visibility cases that constrain how metadata and content is routinely made available to opposing parties in civil litigation, to prosecutors in criminal prosecutions and to agency staff in regulatory enforcement litigation. Public policy, as implemented in the rules of evidence and pretrial discovery, restrict electronic data discovery (EDD as it becomes a predominant and potentially costly pre-trial activity pivotal to modern litigation. This article discusses these constraints while identifying opportunities for the interdisciplinary activities among litigators, forensic experts and information technology professionals.

  13. Day-to-day ionospheric variability due to lower atmosphere perturbations

    Science.gov (United States)

    Liu, H.; Yudin, V. A.; Roble, R. G.

    2013-12-01

    Ionospheric day-to-day variability is a ubiquitous feature, even in the absence of appreciable geomagnetic activities. Although meteorological perturbations have been recognized as an important source of the variability, it is not well represented in previous modeling studies, and the mechanism is not well understood. This study demonstrates that TIME-GCM (Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model) constrained in the stratosphere and mesosphere by the hourly Whole Atmosphere Community Climate Model (WACCM) simulations is capable of reproducing observed features of day-to-day variability in the thermosphere-ionosphere. Realistic weather patterns in the lower atmosphere in WACCM was specified by Modern Era Retrospective reanalysis for Research and Application (MERRA). The day-to-day variations in mean zonal wind, migrating and non-migrating tides in the thermosphere, vertical and zonal ExB drifts, and ionosphere F2 layer peak electron density (NmF2) are examined. The standard deviations of the drifts and NmF2 display local time and longitudinal dependence that compare favorably with observations. Their magnitudes are 50% or more of those from observations. The day-to-day thermosphere and ionosphere variability in the model is primarily caused by the perturbations originated in lower atmosphere, since the model simulation is under constant solar minimum and low geomagnetic conditions.

  14. Day-to-day variability of midlatitude ionospheric currents due to magnetospheric and lower atmospheric forcing

    Science.gov (United States)

    Yamazaki, Y.; Häusler, K.; Wild, J. A.

    2016-07-01

    As known from previous studies on the solar quiet (Sq) variation of the geomagnetic field, the strength and pattern of ionospheric dynamo currents change significantly from day to day. The present study investigates the relative importance of two sources that contribute to the day-to-day variability of the ionospheric currents at middle and low latitudes. One is high-latitude electric fields that are caused by magnetospheric convection, and the other is atmospheric waves from the lower atmosphere. Global ionospheric current systems, commonly known as Sq current systems, are simulated using the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model. Simulations are run for 1-30 April 2010 with a constant solar energy input but with various combinations of high-latitude forcing and lower atmospheric forcing. The model well reproduces geomagnetic perturbations on the ground, when both forcings are taken into account. The contribution of high-latitude forcing to the total Sq current intensity (Jtotal) is generally smaller than the contribution of wave forcing from below 30 km, except during active periods (Kp≥4), when Jtotal is enhanced due to the leakage of high-latitude electric fields to lower latitudes. It is found that the penetration electric field drives ionospheric currents at middle and low latitudes not only on the dayside but also on the nightside, which has an appreciable effect on the Dst index. It is also found that quiet time day-to-day variability in Jtotal is dominated by symmetric-mode migrating diurnal and semidiurnal tidal winds at 45-60° latitude at ˜110 km.

  15. Two-Dimensional Electron Density Measurement of Positive Streamer Discharge in Atmospheric-Pressure Air

    Science.gov (United States)

    Inada, Yuki; Ono, Ryo; Kumada, Akiko; Hidaka, Kunihiko; Maeyama, Mitsuaki

    2016-09-01

    The electron density of streamer discharges propagating in atmospheric-pressure air is crucially important for systematic understanding of the production mechanisms of reactive species utilized in wide ranging applications such as medical treatment, plasma-assisted ignition and combustion, ozone production and environmental pollutant processing. However, electron density measurement during the propagation of the atmospheric-pressure streamers is extremely difficult by using the conventional localized type measurement systems due to the streamer initiation jitters and the irreproducibility in the discharge paths. In order to overcome the difficulties, single-shot two-dimensional electron density measurement was conducted by using a Shack-Hartmann type laser wavefront sensor. The Shack-Hartmann sensor with a temporal resolution of 2 ns was applied to pulsed positive streamer discharges generated in an air gap between pin-to-plate electrodes. The electron density a few ns after the streamer initiation was 7*1021m-3 and uniformly distributed along the streamer channel. The electron density and its distribution profile were compared with a previous study simulating similar streamers, demonstrating good agreement. This work was supported in part by JKA and its promotion funds from KEIRIN RACE. The authors like to thank Mr. Kazuaki Ogura and Mr. Kaiho Aono of The University of Tokyo for their support during this work.

  16. Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks

    Science.gov (United States)

    Zemp, Delphine Clara; Schleussner, Carl-Friedrich; Barbosa, Henrique M. J.; Hirota, Marina; Montade, Vincent; Sampaio, Gilvan; Staal, Arie; Wang-Erlandsson, Lan; Rammig, Anja

    2017-03-01

    Reduced rainfall increases the risk of forest dieback, while in return forest loss might intensify regional droughts. The consequences of this vegetation-atmosphere feedback for the stability of the Amazon forest are still unclear. Here we show that the risk of self-amplified Amazon forest loss increases nonlinearly with dry-season intensification. We apply a novel complex-network approach, in which Amazon forest patches are linked by observation-based atmospheric water fluxes. Our results suggest that the risk of self-amplified forest loss is reduced with increasing heterogeneity in the response of forest patches to reduced rainfall. Under dry-season Amazonian rainfall reductions, comparable to Last Glacial Maximum conditions, additional forest loss due to self-amplified effects occurs in 10-13% of the Amazon basin. Although our findings do not indicate that the projected rainfall changes for the end of the twenty-first century will lead to complete Amazon dieback, they suggest that frequent extreme drought events have the potential to destabilize large parts of the Amazon forest.

  17. Upper limits to the fractionation of isotopes due to atmospheric escape: Implications for potential 14N/15N in Pluto's atmosphere

    Science.gov (United States)

    Mandt, K.; Mousis, O.

    2014-12-01

    Formation and evolution of the solar system is studied in part using stable isotope ratios that are presumed to be primordial, or representative of conditions in the protosolar Nebula. Comets, meteorites and giant planet atmospheres provide measurements that can reasonably be presumed to represent primordial conditions while the terrestrial planets, Pluto and Saturn's moon Titan have atmospheres that have evolved over the history of the solar system. The stable isotope ratios measured in these atmospheres are, therefore, first a valuable tool for evaluating the history of atmospheric escape and once escape is constrained can provide indications of conditions of formation. D/H ratios in the atmosphere of Venus provide indications of the amount of water lost from Venus over the history of the solar system, while several isotope ratios in the atmosphere of Mars provide evidence for long-term erosion of the atmosphere. We have recently demonstrated that the nitrogen ratios, 14N/15N, in Titan's atmosphere cannot evolve significantly over the history of the solar system and that the primordial ratio for Titan must have been similar to the value recently measured for NH3 in comets. This implies that the building blocks for Titan formed in the protosolar nebula rather than in the warmer subnebula surrounding Saturn at the end of its formation. Our result strongly contrasts with works showing that 14N/15N in the atmosphere of Mars can easily fractionate from the terrestrial value to its current value due to escape processes within the lifetime of the solar system. The difference between how nitrogen fractionates in Mars and Titan's atmospheres presents a puzzle for the fractionation of isotopes in an atmosphere due to atmospheric escape. Here, we present a method aiming at determining an upper limit to the amount of fractionation allowed to occur due to escape, which is a function of the escape flux and the column density of the atmospheric constituent. Through this

  18. Fast dropouts of multi-MeV electrons due to combined effects of EMIC and whistler mode waves

    Science.gov (United States)

    Mourenas, D.; Artemyev, A. V.; Ma, Q.; Agapitov, O. V.; Li, W.

    2016-05-01

    We investigate how whole populations of 2-6 MeV electrons can be quickly lost from the Earth's outer radiation belt at L= 3-6 through precipitation into the atmosphere due to quasi-linear pitch angle scattering by combined electromagnetic ion cyclotron (EMIC) and whistler mode waves of realistic intensities occurring at the same or different local times. We provide analytical estimates of the corresponding relativistic electron lifetimes, emphasizing that the combined effects of both waves can lead to very fast (2-10 h) dropouts. Scaling laws for the loss timescales are derived, allowing us to determine the various plasma and wave parameter domains potentially leading to strong and fast dropouts. The analysis reveals that the fastest MeV electron dropouts occur at approximately the same rate over some high energy range and almost independently of EMIC wave amplitudes above a certain threshold. These results should help to better understand the dynamic variability of the radiation belts.

  19. Electrostatic electron cyclotron instabilities near the upper hybrid layer due to electron ring distributions

    Science.gov (United States)

    Eliasson, B.; Speirs, D. C.; Daldorff, L. K. S.

    2016-09-01

    A theoretical study is presented of the electrostatic electron cyclotron instability involving Bernstein modes in a magnetized plasma. The presence of a tenuous thermal ring distribution in a Maxwellian plasma decreases the frequency of the upper hybrid branch of the electron Bernstein mode until it merges with the nearest lower branch with a resulting instability. The instability occurs when the upper hybrid frequency is somewhat above the third, fourth, and higher electron cyclotron harmonics, and gives rise to a narrow spectrum of waves around the electron cyclotron harmonic nearest to the upper hybrid frequency. For a tenuous cold ring distribution together with a Maxwellian distribution an instability can take place also near the second electron cyclotron harmonic. Noise-free Vlasov simulations are used to assess the theoretical linear growth-rates and frequency spectra, and to study the nonlinear evolution of the instability. The relevance of the results to laboratory and ionospheric heating experiments is discussed.

  20. Critical transitions of stratocumulus dynamical systems due to perturbation in free-atmosphere moisture

    Science.gov (United States)

    Tsai, Jia-Ying; Wu, Chien-Ming

    2016-12-01

    The bi-stable behavior of stratocumulus systems is here investigated in a 3D cloud-resolving model based on vector vorticity equations (VVM). This study demonstrates the response of the stratocumulus system to small perturbations of free atmospheric moisture under specified forcings of warm sea surface temperature (SST) and weak subsidence. A critical transition, indicated by the strong decoupling and large variation of cloud properties, separates fast dynamics from slow dynamics. During the fast process governed by the thermodynamic adjustment, the liquid water path (LWP) decreases with a decreasing cloud-top entrainment rate; on the other hand, during the slow process determined by the cloud-top inversion adjustment, LWP increases. The model exhibits two coexisting (cloudy and non-cloudy) quasi-stationary states through the fast process. A key process for the bifurcation is that the non-cloudy state shows the presence of active cumulus convection that allows the destruction of stratocumulus. The results suggest that the direct entrainment drying is enhanced due to an increased moisture gradient across the inversion layer. This tends to develop more broken clouds, which is an important signal for the stratocumulus to cumulus transition. This conceptual model provides a simple framework for developing a timely switch of regime transition in the cloud parameterization in large-scale models.

  1. Broadening of Plasmonic Resonance Due to Electron Collisions with Nanoparticle Boundary: а Quantum Mechanical Consideration

    DEFF Research Database (Denmark)

    Uskov, Alexander; Protsenko, Igor E.; Mortensen, N. Asger

    2014-01-01

    We present a quantum mechanical approach to calculate broadening of plasmonic resonances in metallic nanostructures due to collisions of electrons with the surface of the structure. The approach is applicable if the characteristic size of the structure is much larger than the de Broglie electron ...

  2. Oxidation of the Martian surface - Constraints due to chemical processes in the atmosphere

    Science.gov (United States)

    Mcelroy, M. B.; Kong, T. Y.

    1976-01-01

    Dissociation of water in the Martian atmosphere may supply oxygen to the surface and may result in the formation of minerals such as goethite, as proposed by Huguenin. The supply rate is limited by chemical processes in the atmosphere which regulate the abundance of O2. The net surface sink for atmospheric oxygen can be as large as 33 million atoms per sq cm per sec which compares to the escape rate of 60 million atoms per sq cm per sec.

  3. Secondary Cosmic Ray Particles Due to GCR Interactions in the Earth's Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Battistoni, G.; /Milan U. /INFN, Milan; Cerutti, F.; /CERN; Fasso, A.; /SLAC; Ferrari, A.; /CERN; Garzelli, M.V.; /Milan U. /INFN, Milan; Lantz, M.; /Goteborg, ITP; Muraro, S. /Milan U. /INFN, Milan; Pinsky, L.S.; /Houston U.; Ranft, J.; /Siegen U.; Roesler, S.; /CERN; Sala, P.R.; /Milan U. /INFN, Milan

    2009-06-16

    Primary GCR interact with the Earth's atmosphere originating atmospheric showers, thus giving rise to fluxes of secondary particles in the atmosphere. Electromagnetic and hadronic interactions interplay in the production of these particles, whose detection is performed by means of complementary techniques in different energy ranges and at different depths in the atmosphere, down to the Earth's surface. Monte Carlo codes are essential calculation tools which can describe the complexity of the physics of these phenomena, thus allowing the analysis of experimental data. However, these codes are affected by important uncertainties, concerning, in particular, hadronic physics at high energy. In this paper we shall report some results concerning inclusive particle fluxes and atmospheric shower properties as obtained using the FLUKA transport and interaction code. Some emphasis will also be given to the validation of the physics models of FLUKA involved in these calculations.

  4. Atmospheric ionization induced by precipitating electrons: Comparison of CRAC:EPII model with parametrization model

    CERN Document Server

    Artamonov, A A; Usoskin, I G

    2016-01-01

    A new model CRAC:EPII (Cosmic Ray Atmospheric Cascade: Electron Precipitation Induced Ionization) is presented. The CRAC:EPII is based on Monte Carlo simulation of precipitating electrons propagation and interaction with matter in the Earth atmosphere. It explicitly considers energy deposit: ionization, pair production, Compton scattering, generation of Bremsstrahlung high energy photons, photo-ionization and annihilation of positrons, multiple scattering as physical processes accordingly. The propagation of precipitating electrons and their interactions with atmospheric molecules is carried out with the GEANT4 simulation tool PLANETOCOSMICS code using NRLMSISE 00 atmospheric model. The ionization yields is compared with an analytical parametrization for various energies of incident precipitating electron, using a flux of mono-energetic particles. A good agreement between the two models is achieved. Subsequently, on the basis of balloon-born measured spectra of precipitating electrons at 30.10.2002 and 07.01....

  5. System for transporting an electron beam to the atmosphere for a gun with a plasma emitter

    Science.gov (United States)

    Kornilov, S. Yu.; Rempe, N. G.; Shidlovskiy, S. V.

    2016-06-01

    We report on the results of simulation of the gas flow in a gun with a plasma emitter and in the system for extracting the electron beam to the atmosphere, constructed on the basis of standard gasdynamic windows (GDWs). The design of the gun and GDWs is described. Calculations are performed for a pressure of about 10-3 Torr in the electron beam generation range. It is shown that the pressure drop to the atmospheric pressure in the system of electron beam extraction to the atmosphere can be ensured by two GDW stages evacuated by pumps with optimal performance.

  6. Climate warming due to increasing atmospheric CO2 - Simulations with a multilayer coupled atmosphere-ocean seasonal energy balance model

    Science.gov (United States)

    Li, Peng; Chou, Ming-Dah; Arking, Albert

    1987-01-01

    The transient response of the climate to increasing CO2 is studied using a modified version of the multilayer energy balance model of Peng et al. (1982). The main characteristics of the model are described. Latitudinal and seasonal distributions of planetary albedo, latitude-time distributions of zonal mean temperatures, and latitudinal distributions of evaporation, water vapor transport, and snow cover generated from the model and derived from actual observations are analyzed and compared. It is observed that in response to an atmospheric doubling of CO2, the model reaches within 1/e of the equilibrium response of global mean surface temperature in 9-35 years for the probable range of vertical heat diffusivity in the ocean. For CO2 increases projected by the National Research Council (1983), the model's transient response in annually and globally averaged surface temperatures is 60-75 percent of the corresponding equilibrium response, and the disequilibrium increases with increasing heat diffusivity of the ocean.

  7. Atmospheric gravity waves due to the Tohoku-Oki tsunami observed in the thermosphere by GOCE

    NARCIS (Netherlands)

    Garcia, R.F.; Doornbos, E.N.; Bruinsma, S.; Hebert, H.

    2014-01-01

    Oceanic tsunami waves couple with atmospheric gravity waves, as previously observed through ionospheric and airglow perturbations. Aerodynamic velocities and density variations are computed from Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) accelerometer and thruster data during T

  8. Recent pause in the growth rate of atmospheric CO2 due to enhanced terrestrial carbon uptake

    Science.gov (United States)

    Keenan, Trevor F.; Prentice, I. Colin; Canadell, Josep G.; Williams, Christopher A.; Wang, Han; Raupach, Michael; Collatz, G. James

    2016-11-01

    Terrestrial ecosystems play a significant role in the global carbon cycle and offset a large fraction of anthropogenic CO2 emissions. The terrestrial carbon sink is increasing, yet the mechanisms responsible for its enhancement, and implications for the growth rate of atmospheric CO2, remain unclear. Here using global carbon budget estimates, ground, atmospheric and satellite observations, and multiple global vegetation models, we report a recent pause in the growth rate of atmospheric CO2, and a decline in the fraction of anthropogenic emissions that remain in the atmosphere, despite increasing anthropogenic emissions. We attribute the observed decline to increases in the terrestrial sink during the past decade, associated with the effects of rising atmospheric CO2 on vegetation and the slowdown in the rate of warming on global respiration. The pause in the atmospheric CO2 growth rate provides further evidence of the roles of CO2 fertilization and warming-induced respiration, and highlights the need to protect both existing carbon stocks and regions, where the sink is growing rapidly.

  9. Electron-beam-sustained discharge revisited - light emission from combined electron beam and microwave excited argon at atmospheric pressure

    CERN Document Server

    Dandl, T; Neumeier, A; Wieser, J; Ulrich, A

    2015-01-01

    A novel kind of electron beam sustained discharge is presented in which a 12keV electron beam is combined with a 2.45GHz microwave power to excite argon gas at atmospheric pressure in a continuous mode of operation. Optical emission spectroscopy is performed over a wide wavelength range from the vacuum ultraviolet (VUV) to the near infrared (NIR). Several effects which modify the emission spectra compared to sole electron beam excitation are observed and interpreted by the changing plasma parameters such as electron density, electron temperature and gas temperature.

  10. Thickness of the electron atmosphere in large nuclear systems

    Science.gov (United States)

    Pacheco, A. F.; Sañudo, J.

    1986-03-01

    Using the relativistic Thomas-Fermi model and the virial theorem it is found that the thickness of the electron skin outside a large nuclear system is given by S⋍6.73 n-1/3, n being the electron density inside the nucleus. On leave from Departamento de Fisica Teorica, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza, Spain.

  11. Analytical representation of elastic scattering cross sections of low energy electrons by atmospheric gases

    Science.gov (United States)

    Ivanov, V. Y.; Sipov, N. K.; Shneyder, V. A.

    1977-01-01

    Analytical representations of the elastic scattering cross sections of electrons with energies of 0.01-1 keV in atmospheric gases of N2, O2, O are given. These representations are suitable for the Monte Carlo method.

  12. Magnetic Doppler imaging considering atmospheric structure modifications due to local abundances: a luxury or a necessity?

    Science.gov (United States)

    Kochukhov, O.; Wade, G. A.; Shulyak, D.

    2012-04-01

    Magnetic Doppler imaging is currently the most powerful method of interpreting high-resolution spectropolarimetric observations of stars. This technique has provided the very first maps of stellar magnetic field topologies reconstructed from time series of full Stokes vector spectra, revealing the presence of small-scale magnetic fields on the surfaces of Ap stars. These studies were recently criticised by Stift et al., who claimed that magnetic inversions are not robust and are seriously undermined by neglecting a feedback on the Stokes line profiles from the local atmospheric structure in the regions of enhanced metal abundance. We show that Stift et al. misinterpreted published magnetic Doppler imaging results and consistently neglected some of the most fundamental principles behind magnetic mapping. Using state-of-the-art opacity sampling model atmosphere and polarized radiative transfer codes, we demonstrate that the variation of atmospheric structure across the surface of a star with chemical spots affects the local continuum intensity but is negligible for the normalized local Stokes profiles except for the rare situation of a very strong line in an extremely Fe-rich atmosphere. For the disc-integrated spectra of an Ap star with extreme abundance variations, we find that the assumption of a mean model atmosphere leads to moderate errors in Stokes I but is negligible for the circular and linear polarization spectra. Employing a new magnetic inversion code, which incorporates the horizontal variation of atmospheric structure induced by chemical spots, we reconstructed new maps of magnetic field and Fe abundance for the bright Ap star α2 CVn. The resulting distribution of chemical spots changes insignificantly compared to the previous modelling based on a single model atmosphere, while the magnetic field geometry does not change at all. This shows that the assertions by Stift et al. are exaggerated as a consequence of unreasonable assumptions and

  13. A novel approach to scanning electron microscopy at ambient atmospheric pressure.

    Science.gov (United States)

    Ominami, Yusuke; Kawanishi, Shinsuke; Ushiki, Tatsuo; Ito, Sukehiro

    2015-04-01

    Scanning electron microscopy (SEM) for observing samples at ambient atmospheric pressure is introduced in this study. An additional specimen chamber with a small window is inserted in the main specimen chamber, and the window is separated with a thin membrane or diaphragm allowing electron beam propagation. Close proximity of the sample to the membrane enables the detection of back-scattered electrons sufficient for imaging. In addition to the empirical imaging data, a probability analysis of the un-scattered fraction of the incident electron beam further supports the feasibility of atmospheric SEM imaging over a controlled membrane-sample distance.

  14. Magnetic Doppler imaging considering atmospheric structure modifications due to local abundances: a luxury or a necessity?

    CERN Document Server

    Kochukhov, O; Shulyak, D

    2012-01-01

    Magnetic Doppler imaging is currently the most powerful method of interpreting high-resolution spectropolarimetric observations of stars. This technique has revealed the presence of unexpected small-scale magnetic fields on the surfaces of Ap stars. These studies were recently criticisied by Stift et al. (2012), who claimed that magnetic inversions are not robust and are undermined by neglecting a feedback on the Stokes line profiles from the local atmospheric structure in the regions of enhanced metal abundance. We show that Stift et al. misinterpreted published magnetic Doppler imaging results and neglected some of the most fundamental principles behind magnetic mapping. We demonstrate that the variation of atmospheric structure across the surface of a star with chemical spots affects the local continuum intensity but is negligible for the normalised local Stokes profiles. For the disk-integrated spectra of an Ap star with extreme abundance variations, we find that the assumption of a mean model atmosphere ...

  15. Electron and proton kinetics and dynamics in flaring atmospheres

    CERN Document Server

    Zharkova, Valentina

    2012-01-01

    This timely book presents new research results on high-energy particle physics related to solar flares, covering the theory and applications of the reconnection process in a clear and comprehensible way. It investigates particle kinetics and dynamics in flaring atmospheres and their diagnostics from spectral observations, while providing an analysis of the observation data and techniques and comparing various models. Written by an internationally acclaimed expert, this is vital reading for all solar, astro-, and plasma physicists working in the field.

  16. Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks

    NARCIS (Netherlands)

    Zemp, Delphine Clara; Schleussner, Carl Friedrich; Barbosa, Henrique M.J.; Hirota, Marina; Montade, Vincent; Sampaio, Gilvan; Staal, Arie; Wang-Erlandsson, Lan; Rammig, Anja

    2017-01-01

    © 2017 The Author(s).Reduced rainfall increases the risk of forest dieback, while in return forest loss might intensify regional droughts. The consequences of this vegetation-atmosphere feedback for the stability of the Amazon forest are still unclear. Here we show that the risk of self-amplified Am

  17. A method to correct IACT data for atmospheric absorption due to the Saharan Air Layer

    CERN Document Server

    Dorner, Daniela; Bretz, Thomas

    2008-01-01

    Using the atmosphere as a detector volume, Imaging Air Cherenkov Telescopes (IACTs) depend highly on the properties and the condition of the air mass above the telescope. On the Canary Island of La Palma, where the Major Atmospheric Gamma-ray Imaging Cherenkov telescope (MAGIC) is situated, the Saharan Air Layer (SAL) can cause strong atmospheric absorption affecting the data quality and resulting in a reduced gamma flux. To correlate IACT data with other measurements, e.g. long-term monitoring or Multi-Wavelength (MWL) studies, an accurate flux determination is mandatory. Therefore, a method to correct the data for the effect of the SAL is needed. Three different measurements of the atmospheric absorption are performed on La Palma. From the determined transmission, a correction factor is calculated and applied to the MAGIC data. The different transmission measurements from optical and IACT data provide comparable results. MAGIC data of PG 1553+113, taken during a MWL campaign in July 2006, have been analyzed...

  18. Effect of connecting wires on the decoherence due to electron-electron interaction in a metallic ring

    Science.gov (United States)

    Texier, Christophe

    2007-10-01

    We consider the weak localization in a ring connected to reservoirs through leads of finite length and submitted to a magnetic field. The effect of decoherence due to electron-electron interaction on the harmonics of Al’tshuler-Aronov-Spivak [JETP Lett. 33, 94 (1981)] oscillations is studied, and more specifically the effect of the leads. Two results are obtained for short and long lead regimes. The scale at which the crossover occurs is discussed. The long lead regime is shown to be more realistic experimentally.

  19. Characteristics of charge and discharge of PMMA samples due to electron irradiation

    Institute of Scientific and Technical Information of China (English)

    封国宝; 王芳; 胡天存; 曹猛

    2015-01-01

    In this study, using a comprehensive numerical simulation of charge and discharge processes, we investigate the formation and evolution of negative charge and discharge characteristics of a grounded PMMA film irradiated by a non-focused electron beam. Electron scattering and transport processes in the sample are simulated with the Monte Carlo and the finite-different time-domain (FDTD) methods, respectively. The properties of charge and discharge processes are presented by the evolution of internal currents, charge quantity, surface potential, and discharge time. Internal charge accumulation in the sample may reach saturation by primary electron (PE) irradiation providing the charge duration is enough. Internal free electrons will run off to the ground in the form of leakage current due to charge diffusion and drift during the discharge process after irradiation, while trapped electrons remain. The negative surface potential determined by the charging quantity decreases to its saturation in the charge process, and then increases in the discharge process. A larger thickness of the PMMA film will result in greater charge amount and surface potential in charge saturation and in final discharge state, while the electron mobility of the material has little effects on the final discharge state. Moreover, discharge time is less for smaller thickness or larger electron mobility. The presented results can be helpful for estimating and weakening the charging of insulating samples especially under the intermittent electron beam irradiation in related surface analysis or measurement.

  20. Parameters of a supershort avalanche electron beam generated in atmospheric-pressure air

    Science.gov (United States)

    Tarasenko, V. F.

    2011-05-01

    Conditions under which the number of runaway electrons in atmospheric-pressure air reaches ˜5 × 1010 are determined. Recommendations for creating runaway electron accelerators are given. Methods for measuring the parameters of a supershort avalanche electron beam and X-ray pulses from gas-filled diodes, as well as the discharge current and gap voltage, are described. A technique for determining the instant of runaway electron generation with respect to the voltage pulse is proposed. It is shown that the reduction in the gap voltage and the decrease in the beam current coincide in time. The mechanism of intense electron beam generation in gas-filled diodes is analyzed. It is confirmed experimentally that, in optimal regimes, the number of electrons generated in atmospheric-pressure air with energies T > eU m , where U m is the maximum gap voltage, is relatively small.

  1. Electron cooling by carbon monoxide in the atmospheres of Mars and Venus

    CERN Document Server

    Campbell, Laurence

    2008-01-01

    Electron cooling, in which free electrons lose energy to vibrational excitation of gases, has been identified as a significant process in the atmospheres of Mars and Venus for electron impact on CO2. This process does not appear to have been evaluated for CO, although the density of CO exceeds that of CO2 in the upper atmospheres of these planets. In this paper electron cooling rates for CO are calculated and compared with existing rates for CO2. It is found that electron cooling by CO becomes more significant than by CO2 above altitudes of about 300 km on Mars and about 168 km on Venus. The sensitivity of the calculated cooling rates to different measurements of the integral cross sections for electron-impact vibrational excitation of CO is also investigated. PACS Codes: 34.80.Gs, 96.12.Jt

  2. Temperature rise in objects due to optical focused beam through atmospheric turbulence near ground and ocean surface

    Science.gov (United States)

    Stoneback, Matthew; Ishimaru, Akira; Reinhardt, Colin; Kuga, Yasuo

    2013-03-01

    We consider an optical beam propagated through the atmosphere and incident on an object causing a temperature rise. In clear air, the physical characteristics of the optical beam transmitted to the object surface are influenced primarily by the effect of atmospheric turbulence, which can be significant near the ground or ocean surface. We use a statistical model to quantify the expected power transfer through turbulent atmosphere and provide guidance toward the threshold of thermal blooming for the considered scenarios. The bulk thermal characteristics of the materials considered are used in a thermal diffusion model to determine the net temperature rise at the object surface due to the incident optical beam. These results of the study are presented in graphical form and are of particular interest to operators of high power laser systems operating over large distances through the atmosphere. Numerical examples include a CO2 laser (λ=10.6 μm) with: aperture size of 5 cm, varied pulse duration, and propagation distance of 0.5 km incident on 0.1-mm copper, 10-mm polyimide, 1-mm water, and 10-mm glass/resin composite targets. To assess the effect of near ground/ocean laser propagation, we compare turbulent (of varying degrees) and nonturbulent atmosphere.

  3. Overvoltage analysis on submarine cables of atmospheric origin and due to switching operations

    Energy Technology Data Exchange (ETDEWEB)

    Puharic, M.; Wagmann, L.; Zutobradic, S. [Energy Inst. ``Hrvoje Pozar`` (Croatia)

    1997-12-31

    In 1995, about 100 km of submarine cables were laid to improve electricity supply of the Adriatic islands. The cables were connected to the existing 35 kV grid. Six substations of 35/10 kV were either constructed or reconstructed with the underground connective cables of 35 kV. Since these are very important electric power facilities, a detailed calculation of expected internal and atmospheric overvoltages on submarine cables was carried out. This paper gives the basis of the theoretical model used for overvoltage calculations as well as the calculation results of one characteristic case. (Author)

  4. Corrosion failure due to flux residues in an electronic add-on device

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Minzari, Daniel; Rathinavelu, Umadevi

    2010-01-01

    contamination is solder flux residues which can act as a corrosion promoter in humid atmosphere due to the presence of ionic substances and a resin component. The presence of ionic substances will increase the conductivity of a condensed water layer and influence corrosion processes, depending on the species...... present. The resin component can easily attract dust during operation, which will eventually make surfaces hydrophilic and are thus become a potential source for ions. This paper describes the failure analysis of tactile switches, used in PCBAs mounted in wind turbines. More detailed investigation...

  5. Model for ground motion and atmospheric overpressure due to underground nuclear explosion

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H.; Walker, J.J.

    1980-10-01

    A physical model is proposed to describe the ground motion pattern resulting from an underground nulear explosion in an idealized homogeneous medium. Irregular behaviors in the observed ground motion are assumed to be perturbations caused by the local inhomogeneity of the ground medium. Our model correlates the ground motions at any point in the spalled zone to the initial acceleration pulse at the ground zero. Interestingly, the model predicts that the ground motion first comes to a stop at a definite radius about the ground zero, and the region expands both outward and inward as time goes on. We believe that this result is closely related to a phenomenon observed at NTS. In the far field approximation, we also calculate the overpressure in the lower atmosphere generated by the ground motion. We demonstrate that the irregular component of the ground motion does not affect the overpressure history in any significant way. Consequently the model ground motion can be used as a good approximation in generating the atmospheric overpressure.

  6. Limitation of Ground-based Estimates of Solar Irradiance Due to Atmospheric Variations

    Science.gov (United States)

    Wen, Guoyong; Cahalan, Robert F.; Holben, Brent N.

    2003-01-01

    The uncertainty in ground-based estimates of solar irradiance is quantitatively related to the temporal variability of the atmosphere's optical thickness. The upper and lower bounds of the accuracy of estimates using the Langley Plot technique are proportional to the standard deviation of aerosol optical thickness (approx. +/- 13 sigma(delta tau)). The estimates of spectral solar irradiance (SSI) in two Cimel sun photometer channels from the Mauna Loa site of AERONET are compared with satellite observations from SOLSTICE (Solar Stellar Irradiance Comparison Experiment) on UARS (Upper Atmospheric Research Satellite) for almost two years of data. The true solar variations related to the 27-day solar rotation cycle observed from SOLSTICE are about 0.15% at the two sun photometer channels. The variability in ground-based estimates is statistically one order of magnitude larger. Even though about 30% of these estimates from all Level 2.0 Cimel data fall within the 0.4 to approx. 0.5% variation level, ground-based estimates are not able to capture the 27-day solar variation observed from SOLSTICE.

  7. Atmospheric ionization induced by precipitating electrons: Comparison of CRAC:EPII model with a parametrization model

    Science.gov (United States)

    Artamonov, A. A.; Mishev, A. L.; Usoskin, I. G.

    2016-11-01

    Results of a comparison of a new model CRAC:EPII (Cosmic Ray Atmospheric Cascade: Electron Precipitation Induced Ionization) with a commonly used parametric model of atmospheric ionization is presented. The CRAC:EPII is based on a Monte Carlo simulation of precipitating electrons propagation and interaction with matter in the Earth's atmosphere. It explicitly considers energy deposit: ionization, pair production, Compton scattering, generation of Bremsstrahlung high energy photons, photo-ionization and annihilation of positrons, multiple scattering as physical processes accordingly. Propagation of precipitating electrons and their interactions with air is simulated with the GEANT4 simulation tool PLANETOCOSMICS code using NRLMSISE-00 atmospheric model. Ionization yields are computed and compared with a parametrization model for different energies of incident precipitating energetic electrons, using simulated fluxes of mono-energetic particles. A good agreement between the two models is achieved in the mesosphere but the contribution of Bremsstrahlung in the stratosphere, which is not accounted for in the parametric models, is found significant. As an example, we calculated profiles of the ion production rates in the middle and upper atmosphere (below 100 km) on the basis of balloon-born measured spectra of precipitating electrons for 30-October-2002 and 07-January-2004.

  8. Internal electron transport barrier due to neoclassical ambipolarity in the Helically Symmetric Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Lore, J. [University of Wisconsin, Madison; Guttenfelder, Walter [University of Warwick, UK; Briesemeister, Alexis [HSX Laboratory, University of Wisconsin-Madison; Anderson, David [HSX Laboratory, University of Wisconsin-Madison; Anderson, F. S.B. [University of Wisconsin, Madison; Deng, C. B. [University of California; Likin, K. [University of Wisconsin, Madison; Spong, Donald A [ORNL; Talmadge, Joseph [HSX Laboratory, University of Wisconsin-Madison; Zhai, Kan [HSX Laboratory, University of Wisconsin-Madison

    2010-01-01

    Electron cyclotron heated plasmas in the Helically Symmetric Experiment (HSX) feature strongly peaked electron temperature profiles; central temperatures are 2.5 keV with 100 kW injected power. These measurements, coupled with neoclassical predictions of large 'electron root' radial electric fields with strong radial shear, are evidence of a neoclassically driven thermal transport barrier. Neoclassical transport quantities are calculated using the PENTA code [D. A. Spong, Phys. Plasmas 12, 056114 (2005)], in which momentum is conserved and parallel flow is included. Unlike a conventional stellarator, which exhibits strong flow damping in all directions on a flux surface, quasisymmetric stellarators are free to rotate in the direction of symmetry, and the effect of momentum conservation in neoclassical calculations may therefore be significant. Momentum conservation is shown to modify the neoclassical ion flux and ambipolar ion root radial electric fields in the quasisymmetric configuration. The effect is much smaller in a HSX configuration where the symmetry is spoiled. In addition to neoclassical transport, a model of trapped electron mode turbulence is used to calculate the turbulent-driven electron thermal diffusivity. Turbulent transport quenching due to the neoclassically predicted radial electric field profile is needed in predictive transport simulations to reproduce the peaking of the measured electron temperature profile [Guttenfelder et al., Phys. Rev. Lett. 101, 215002 (2008)].

  9. Internal electron transport barrier due to neoclassical ambipolarity in the Helically Symmetric Experimenta)

    Science.gov (United States)

    Lore, J.; Guttenfelder, W.; Briesemeister, A.; Anderson, D. T.; Anderson, F. S. B.; Deng, C. B.; Likin, K. M.; Spong, D. A.; Talmadge, J. N.; Zhai, K.

    2010-05-01

    Electron cyclotron heated plasmas in the Helically Symmetric Experiment (HSX) feature strongly peaked electron temperature profiles; central temperatures are 2.5 keV with 100 kW injected power. These measurements, coupled with neoclassical predictions of large "electron root" radial electric fields with strong radial shear, are evidence of a neoclassically driven thermal transport barrier. Neoclassical transport quantities are calculated using the PENTA code [D. A. Spong, Phys. Plasmas 12, 056114 (2005)], in which momentum is conserved and parallel flow is included. Unlike a conventional stellarator, which exhibits strong flow damping in all directions on a flux surface, quasisymmetric stellarators are free to rotate in the direction of symmetry, and the effect of momentum conservation in neoclassical calculations may therefore be significant. Momentum conservation is shown to modify the neoclassical ion flux and ambipolar ion root radial electric fields in the quasisymmetric configuration. The effect is much smaller in a HSX configuration where the symmetry is spoiled. In addition to neoclassical transport, a model of trapped electron mode turbulence is used to calculate the turbulent-driven electron thermal diffusivity. Turbulent transport quenching due to the neoclassically predicted radial electric field profile is needed in predictive transport simulations to reproduce the peaking of the measured electron temperature profile [Guttenfelder et al., Phys. Rev. Lett. 101, 215002 (2008)].

  10. Clarifying the covariant formalism for the SZ effect due to relativistic non-thermal electrons

    CERN Document Server

    Boehm, Celine

    2008-01-01

    We derive the covariant formalism associated with the relativistic Sunyaev-Zel'dovich effect due to a non-thermal population of high energy electrons in clusters of galaxies. More precisely, we show that the formalism proposed by Wright in 1979, based on an empirical approach (but widely used in the literature) to compute the inverse Compton scattering of a population of relativistic electrons on CMB photons, can actually be re-interpreted as a Boltzmann-like equation, in the single scattering approximation. Although this would tend to reconcile Wright's approach with the latest works on the relativistic corrections of the thermal SZ effect, we find that the squared matrix amplitude derived by Wright by applying a relativistic Lorentz boost on Chandrasekhar's non-relativistic formula is incorrect (it is not equivalent to the well-known Compton scattering squared matrix amplitude in the limit of relativistic incoming electrons and low energy photons). This has important consequences. In particular, this modifi...

  11. Standing striations due to ionization instability in atmospheric pressure He/H2O radio frequency capacitive discharges

    Science.gov (United States)

    Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J.

    2016-10-01

    One-dimensional particle-in-cell (PIC) simulations of a narrow gap atmospheric pressure He/2%{{\\text{H}}2}\\text{O} radio frequency capacitive discharge showed standing striations in the bulk plasma region while previously conducted PIC simulations of a narrow gap atmospheric pressure He/0.1%{{\\text{N}}2} discharges [1] showed no such instabilities. We successively modified the base He/{{\\text{H}}2}\\text{O} chemistry to make it more similar to the He/{{\\text{N}}2} chemistry in order to determine the cause of the striations. Setting the e-{{\\text{H}}2}\\text{O} scattering, attachment, vibrational and rotational excitation rates to zero did not suppress the striations. However, a systematic reduction of the e-ion recombination cross section resulted in a transition to a stable state with no striations. The results are interpreted in terms of a model in which the balance between bulk direct ionization and bulk recombination loss determines the bulk plasma equilibrium. Perturbing the equilibrium, we find that the striations are consistent with an ionization instability induced by non-local electron kinetics that form a spatially-varying high energy tail of the electron energy distribution, causing the ionization rate coefficient to decrease with increasing electron temperature T e and root-mean-square electric field E in the instability regime.

  12. Calculating the X-Ray Fluorescence from the Planet Mercury Due to High-Energy Electrons

    Science.gov (United States)

    Burbine, T. H.; Trombka, J. I.; Bergstrom, P. M., Jr.; Christon, S. P.

    2005-01-01

    The least-studied terrestrial planet is Mercury due to its proximity to the Sun, which makes telescopic observations and spacecraft encounters difficult. Our lack of knowledge about Mercury should change in the near future due to the recent launching of MESSENGER, a Mercury orbiter. Another mission (BepiColombo) is currently being planned. The x-ray spectrometer on MESSENGER (and planned for BepiColombo) can characterize the elemental composition of a planetary surface by measuring emitted fluorescent x-rays. If electrons are ejected from an atom s inner shell by interaction with energetic particles such as photons, electrons, or ions, electrons from an outer shell can transfer to the inner shell. Characteristic x-rays are then emitted with energies that are the difference between the binding energy of the ion in its excited state and that of the ion in its ground state. Because each element has a unique set of energy levels, each element emits x-rays at a unique set of energies. Electrons and ions usually do not have the needed flux at high energies to cause significant x-ray fluorescence on most planetary bodies. This is not the case for Mercury where high-energy particles were detected during the Mariner 10 flybys. Mercury has an intrinsic magnetic field that deflects the solar wind, resulting in a bow shock in the solar wind and a magnetospheric cavity. Electrons and ions accelerated in the magnetosphere tend to follow its magnetic field lines and can impact the surface on Mercury s dark side Modeling has been done to determine if x-ray fluorescence resulting from the impact of high-energy electrons accelerated in Mercury's magnetosphere can be detected by MESSENGER. Our goal is to understand how much bulk chemical information can be obtained from x-ray fluorescence measurements on the dark side of Mercury.

  13. Modulation in Ocean Primary Production due to Variability of Photosynthetically Available Radiation under Different Atmospheric Conditions

    Directory of Open Access Journals (Sweden)

    Madhumita Tripathy

    2014-01-01

    Full Text Available The rate of photosynthesis primarily depends on nutrients and photosynthetically available radiation (PAR at sea surface. Several ship cruises were carried out to measure optical, biological, and atmospheric parameters in the Arabian Sea and their variability were studied. An analytical nonspectral photosynthesis-irradiance model was used to estimate euphotic primary production (EuPP to study its variability during cruise periods. PAR was estimated using COART model using in situ measured aerosol optical depth (AOD to compare with in situ measured PAR. In order to understand the variability of PAR under different types of aerosol and different aerosol loading, a simulation study was carried out using COART model. EuPP was estimated for various PAR values under different aerosol loading and cloud coverage conditions. Sensitivity analysis showed that for maritime, maritime polluted, and desert aerosols, the ratio PAR/PAR0AOD has attenuated to about 11–25%, whereas it has attenuated to 44% for urban aerosol type. PAR/PARclear  sky was reduced by ~57% for high aerosol loading and for overcast sky. The decrease in EuPP under various aerosol loading and cloud coverage was observed to depend on the photoadaptation parameter. EuPP/EuPPclear  sky was reduced by 38% for maximum maritime aerosol loading and for overcast sky.

  14. Acceleration of Plasma Flows in the Solar Atmosphere Due to Magnetofluid Coupling - Simulation and Analysis

    CERN Document Server

    Mahajan, S M; Mikeladze, S V; Sigua, K I; Mahajan, Swadesh M.; Shatashvili, Nana L.; Mikeladze, Solomon V.; Sigua, Ketevan I.

    2005-01-01

    Within the framework of a two-fluid description possible pathways for the generation of fast flows (dynamical as well as steady) in the lower solar atmosphere is established. It is shown that a primary plasma flow (locally sub-Alfv\\'enic) is accelerated when interacting with emerging/ambient arcade--like closed field structures. The acceleration implies a conversion of thermal and field energies to kinetic energy of the flow. The time-scale for creating reasonably fast flows ($\\gtrsim 100$ km/s) is dictated by the initial ion skin depth while the amplification of the flow depends on local $\\beta $. It is shown, for the first time, that distances over which the flows become "fast" are $\\sim 0.01 R_s$ from the interaction surface; later the fast flow localizes (with dimensions $\\lesssim 0.05 R_S$) in the upper central region of the original arcade. For fixed initial temperature the final speed ($\\gtrsim 500 km/s$) of the accelerated flow, and the modification of the field structure are independent of the time-d...

  15. Energy distribution of runaway electrons generated by a nanosecond discharge in atmospheric-pressure air

    Science.gov (United States)

    Tarasenko, V. F.; Baksht, E. Kh.; Burachenko, A. G.; Kostyrya, I. D.; Lomaev, M. I.; Petin, V. K.; Rybka, D. V.; Shlyakhtun, S. V.

    2008-12-01

    The spectra of an ultrashort avalanche electron beam generated by a nanosecond discharge in atmospheric-pressure air were investigated. The temporal characteristics of the beam current pulses, gap voltage, and discharge current in a gas diode were measured with a time resolution of ˜0.1 ns. A simple technique was developed for recovering electron spectra from the curves of beam attenuation by aluminum foils. The effect of the cathode design, electrode gap length, and generator parameters on the electron spectra were studied using seven setups. It is shown that generation of electrons with anomalously high energies requires the use of cathodes with increased curvature radius.

  16. Atmospheric transport of radionuclides emitted due to wildfires near the Chernobyl Nuclear Power Plant in 2015

    Science.gov (United States)

    Evangeliou, Nikolaos; Zibtsev, Sergey; Myroniuk, Viktor; Zhurba, Marina; Hamburger, Thomas; Stohl, Andreas; Balkanski, Yves; Paugam, Ronan; Mousseau, Timothy A.; Møller, Anders P.; Kireev, Sergey I.

    2016-04-01

    In 2015, two major fires in the Chernobyl Exclusion Zone (CEZ) have caused concerns about the secondary radioactive contamination that might have spread over Europe. The total active burned area was estimated to be about 15,000 hectares, of which 9000 hectares burned in April and 6000 hectares in August. The present paper aims to assess, for the first time, the transport and impact of these fires over Europe. For this reason, direct observations of the prevailing deposition levels of 137Cs and 90Sr, 238Pu, 239Pu, 240Pu and 241Am in the CEZ were processed together with burned area estimates. Based on literature reports, we made the conservative assumption that 20% of the deposited labile radionuclides 137Cs and 90Sr, and 10% of the more refractory 238Pu, 239Pu, 240Pu and 241Am, were resuspended by the fires. We estimate that about 10.9 TBq of 137Cs, 1.5 TBq of 90Sr, 7.8 GBq of 238Pu, 6.3 GBq of 239Pu, 9.4 GBq of 240Pu and 29.7 GBq of 241Am were released from both fire events. These releases could be classified as of "Level 3" on the relative INES (International Nuclear Events Scale) scale, which corresponds to a serious incident, in which non-lethal deterministic effects are expected from radiation. To simulate the dispersion of the resuspended radionuclides in the atmosphere and their deposition onto the terrestrial environment, we used a Lagrangian dispersion model. Spring fires redistributed radionuclides over the northern and eastern parts of Europe, while the summer fires also affected Central and Southern Europe. The more labile elements escaped more easily from the CEZ and then reached and deposited in areas far from the source, whereas the larger refractory particles were removed more efficiently from the atmosphere and thus did mainly affect the CEZ and its vicinity. For the spring 2015 fires, we estimate that about 80% of 137Cs and 90Sr and about 69% of 238Pu, 239Pu, 240Pu and 241Am were deposited over areas outside the CEZ. 93% of the labile and 97% of

  17. Ion Emittance Growth Due to Focusing Modulation from Slipping Electron Bunch

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2015-02-17

    Low energy RHIC operation has to be operated at an energy ranging from γ = 4.1 to γ = 10. The energy variation causes the change of revolution frequency. While the rf system for the circulating ion will operate at an exact harmonic of the revolution frequency (h=60 for 4.5 MHz rf and h=360 for 28 MHz rf.), the superconducting rf system for the cooling electron beam does not have a frequency tuning range that is wide enough to cover the required changes of revolution frequency. As a result, electron bunches will sit at different locations along the ion bunch from turn to turn, i.e. the slipping of the electron bunch with respect to the circulating ion bunch. At cooling section, ions see a coherent focusing force due to the electrons’ space charge, which differs from turn to turn due to the slipping. We will try to estimate how this irregular focusing affects the transverse emittance of the ion bunch.

  18. New Microwave Diagnostic Theory for Measurement of Electron Density in Atmospheric Plasmas

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shu; HU Xi-Wei

    2005-01-01

    @@ We present the phase shift of an electromagnetic wave passing through an atmospheric plasma layer. In this kind of plasma, the phase shift depends not only on the line average electron density and layer width, but also on the electron-neutral collision frequency. Since the collision frequency is close to or even larger than the incident microwave frequency, a one-dimensional code for the numerical solution of the wave equation with full time and space variables is established to give the phase shift. When the width and the pressure (hence the electron-neutral collision frequency) are known, the measurement of phase shift will uniquely determine the line average electrons density in an atmospheric plasma.

  19. Energy loss of a fast-electron beam due to the excitation of collective oscillation in hot plasma

    Institute of Scientific and Technical Information of China (English)

    Ma Jin-Yi; Qiu Xi-Jun; Zhu Zhi-Yuan

    2004-01-01

    Energy loss due to a fast-electron beam interacting with the hot plasma at a high density is analysed theoretically.By splitting the particle density fluctuations into the individual part due to the random thermal motion of the individual electrons and the collective part due to plasma-wave excitation, we are concerned with the collective interaction of the relativistic plasma electrons resulting from the Coulomb interactions. Consequently, we derive the frequency of the hot plasma and the "Debye length" with the modification of the relativistic effect. And finally we calculate the energy loss of a fast-electron beam due to the excitation of collective oscillation in the hot plasma.

  20. Software-based mitigation of image degradation due to atmospheric turbulence

    Science.gov (United States)

    Huebner, Claudia S.; Scheifling, Corinne

    2010-10-01

    Motion-Compensated Averaging (MCA) with blind deconvolution has proven successful in mitigating turbulence effects like image dancing and blurring. In this paper an image quality control according to the "Lucky Imaging" principle is combined with the MCA-procedure, weighting good frames more heavily than bad ones, skipping a given percentage of extremely degraded frames entirely. To account for local isoplanatism, when image dancing will effect local displacements between consecutive frames rather than global shifts only, a locally operating MCA variant with block matching, proposed in earlier work, is employed. In order to reduce loss of detail due to normal averaging, various combinations of temporal mode, median and mean are tested as reference image. The respective restoration results by means of a weighted blind deconvolution algorithm are presented and evaluated.

  1. Numerical study of secondary electron emission in a coaxial radio-frequency driven plasma jet at atmospheric pressure

    CERN Document Server

    Hemke, Torben; Wollny, Alexander; Brinkmann, Ralf Peter; Mussenbrock, Thomas

    2011-01-01

    In this work we investigate a numerical model of a coaxial RF-driven plasma jet operated at atmospheric pressure. Due to the cylindrical symmetry an adequate 2-D representation of the otherwise 3-dimensional structure is used. A helium-oxygen chemistry reaction scheme is applied. We study the effect of secondary electrons emitted at the inner electrode as well as the inserted dielectric tube and discuss their impact on the discharge behavior. We conclude that a proper choice of materials can improve the desired mode of operation of such plasma jets in terms of materials and surface processing.

  2. Enhancement of threshold electric field for relativistic runaway electrons due to magnetic fluctuation and synchrotron radiation

    Science.gov (United States)

    Li, Shucai; Wang, Lu; Chen, Zhongyong; Huang, Duwei; Tong, Ruihai

    2016-10-01

    The dynamics of relativistic electrons are analyzed using the relativistic Fokker-Planck equation including deceleration due to synchrotron radiation (SR) and radial diffusion loss caused by magnetic fluctuation (MF). Threshold electric field for avalanche growth is enhanced, and the growth rate is reduced by the combined effect of MF and SR as compared to the case with only SR. The threshold electric field is determined by the time scales balance between momentum evolution and radial diffusion loss induced by MF, and increased with level of MF. More importantly, the hysteresis behavior of runaway pointed out by does not exist anymore. This is because the ``seed electrons'' cannot be sustained as a result of diffusion loss. This work was supported by NSFC Grant No. 11305071, and the Ministry of Science and technology of China, under Contract Nos. 2013GB112002, 2015GB111002 and 2015GB111001.

  3. External costs of atmospheric Pb emissions: valuation of neurotoxic impacts due to inhalation

    Directory of Open Access Journals (Sweden)

    Frohn Lise

    2010-02-01

    Full Text Available Abstract Background The Impact Pathway Approach (IPA is an innovative methodology to establish links between emissions, related impacts and monetary estimates. Only few attempts have so far been presented regarding emissions of metals; in this study the external costs of airborne lead (Pb emissions are assessed using the IPA. Exposure to Pb is known to provoke impacts especially on children's cognition. As cognitive abilities (measured as IQ, intelligence quotient are known to have implications for lifetime income, a pathway can be established leading from figures for Pb emissions to the implied loss in earnings, and on this basis damage costs per unit of Pb emission can be assessed. Methods Different types of models are here linked. It is relatively straightforward to establish the relationship between Pb emissions and consequent increase in air-Pb concentration, by means of a Gaussian plume dispersion model (OML. The exposed population can then be modelled by linking the OML-output to population data nested in geo-referenced grid cells. Less straightforward is to establish the relationship between exposure to air-Pb concentrations and the resulting blood-Pb concentration. Here an Age-Dependent Biokinetic Model (ADBM for Pb is applied. On basis of previous research which established links between increases in blood-Pb concentrations during childhood and resulting IQ-loss we arrive at our results. Results External costs of Pb airborne emissions, even at low doses, in our site are in the range of 41-83 €/kg emitted Pb, depending on the considered meteorological year. This estimate applies only to the initial effects of air-Pb, as our study does not address the effects due to the Pb environmental-accumulation and to the subsequent Pb re-exposure. These are likely to be between one and two orders of magnitude higher. Conclusions Biokinetic modelling is a novel tool not previously included when applying the IPA to explore impacts of Pb emissions

  4. Uncertainties in atmospheric chemistry modelling due to convection parameterisations and subsequent scavenging

    Directory of Open Access Journals (Sweden)

    H. Tost

    2010-02-01

    Full Text Available Moist convection in global modelling contributes significantly to the transport of energy, momentum, water and trace gases and aerosols within the troposphere. Since convective clouds are on a scale too small to be resolved in a global model their effects have to be parameterised. However, the whole process of moist convection and especially its parameterisations are associated with uncertainties. In contrast to previous studies on the impact of convection on trace gases, which had commonly neglected the convective transport for some or all compounds, we investigate this issue by examining simulations with five different convection schemes. This permits an uncertainty analysis due to the process formulation, without the inconsistencies inherent in entirely neglecting deep convection or convective tracer transport for one or more tracers.

    Both the simulated mass fluxes and tracer distributions are analysed. Investigating the distributions of compounds with different characteristics, e.g., lifetime, chemical reactivity, solubility and source distributions, some differences can be attributed directly to the transport of these compounds, whereas others are more related to indirect effects, such as the transport of precursors, chemical reactivity in certain regions, and sink processes.

    The model simulation data are compared with the average regional profiles of several measurement campaigns, and in detail with two campaigns in fall and winter 2005 in Suriname and Australia, respectively.

    The shorter-lived a compound is, the larger the differences and consequently the uncertainty due to the convection parameterisation are, as long as it is not completely controlled by local production that is independent of convection and its impacts (e.g. water vapour changes. Whereas for long-lived compounds like CO or O3 the mean differences between the simulations are less than 25%, differences for short-lived compounds reach

  5. Electron localization due to side-attached molecules on graphene nanoribbons

    Science.gov (United States)

    Nunez, C. D.; Orellana, P. A.; Rosales, L.

    2016-10-01

    In this work, we have studied the electron localization due to a random distribution of side-attached linear organic molecules on graphene nanoribbons. By using the Green's function formalism within a tight binding Hamiltonian approximation and considering an Anderson-like disorder, we have calculated the conductance of the systems and the corresponding localization lengths. Our results show that the localization length strongly depends on the molecular concentration and on the length of the molecules, effects that are robust for different ribbon widths. These results suggest possible applications in molecular detectors or sensors based on graphene nanoribbons.

  6. Numerical Simulation of the Self-Heating Effect Induced by Electron Beam Plasma in Atmosphere

    Institute of Scientific and Technical Information of China (English)

    邓永锋; 谭畅; 韩先伟; 谭永华

    2012-01-01

    For exploiting advantages of electron beam air plasma in some unusual applications, a Monte Carlo (MC) model coupled with heat transfer model is established to simulate the characteristics of electron beam air plasma by considering the self-heating effect. Based on the model, the electron beam induced temperature field and the related plasma properties are investigated. The results indicate that a nonuniform temperature field is formed in the electron beam plasma region and the average temperature is of the order of 600 K. Moreover, much larger volume pear-shaped electron beam plasma is produced in hot state rather than in cold state. The beam ranges can, with beam energies of 75 keV and 80 keV, exceed 1.0 m and 1.2 m in air at pressure of 100 torr, respectively. Finally, a well verified formula is obtained for calculating the range of high energy electron beam in atmosphere.

  7. Plasma density enhancements created by the ionization of the Earth's upper atmosphere by artificial electron beams

    DEFF Research Database (Denmark)

    Neubert, Torsten; Banks, P.M.

    We present analytical calculations and experimental observations relating to the interaction with the Earth's upper atmosphere of electron beams emitted from low altitude spacecraft. The problem is described by two coupled non-linear differential equations in the up-going (along a magnetic field ...

  8. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hiromasa [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Mizuno, Masaaki [Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Toyokuni, Shinya [Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Maruyama, Shoichi [Department of Nephrology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kodera, Yasuhiro [Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Terasaki, Hiroko [Department of Ophthalmology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Adachi, Tetsuo [Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu (Japan); Kato, Masashi [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kikkawa, Fumitaka [Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Hori, Masaru [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-12-15

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  9. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Science.gov (United States)

    Tanaka, Hiromasa; Mizuno, Masaaki; Toyokuni, Shinya; Maruyama, Shoichi; Kodera, Yasuhiro; Terasaki, Hiroko; Adachi, Tetsuo; Kato, Masashi; Kikkawa, Fumitaka; Hori, Masaru

    2015-12-01

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  10. Dynamic Evolution of Outer Radiation Belt Electrons due to Whistler-Mode Chorus

    Institute of Scientific and Technical Information of China (English)

    SU Zhen-Peng; ZHENG Hui-Nan; XIONG Ming

    2009-01-01

    Following our preceding work,we perform a further study on dynamic evolution of energetic electrons in the outer radiation belt L = 4.5 due to a band of whistler-mode chorus frequency distributed over a standard Gaussian spectrum.We solve the 2D bounce-averaged Fokker-Planck equation by allowing incorporation of cross diffusion rates.Numerical results show that whistler-mode chorus can be effective in acceleration of electrons at large pitch angles,and enhance the phase space density for energies of about 1MeV by a factor of 102 or above in about one day,consistent with observation of significant enhancement in flux of energetic electrons during the recovery phase of a geomagnetic storm.Moreover,neglecting cross diffusion often leads to overestimates of the phase space density evolution at large pitch angle by a factor of 5-10 after one day,with larger errors at smaller pitch angle,suggesting that cross diffusion also plays an important role in wave-particle interaction.

  11. Generation of Electron Suprathermal Tails in the Upper Solar Atmosphere: Implications for Coronal Heating

    Science.gov (United States)

    Vinas, Adolfo F.; Wong, Hung K.; Klimas, Alexander J.

    1999-01-01

    We present a mechanism for the generation of non-Maxwellian electron distribution function in the upper regions of the solar atmosphere in the presence of collisional damping. It is suggested that finite amplitude, low frequency, obliquely propagating electromagnetic waves can carry a substantial electric field component parallel to the mean magnetic field that can be significantly larger than the Dreicer electric field. This long wavelength electric fluctuation is capable of generating high frequency electron plasma oscillations and low frequency ion acoustic-like waves. The analysis has been performed using 1-1/2D Vlasov and PIC numerical simulations in which both electrons and ions are treated kinetically and self consistently. The simulation results indicate that high frequency electron plasma oscillations and low frequency ion acoustic-like waves are generated. The high frequency electron plasma oscillation drives electron plasma turbulence, which subsequently is damped out by the background electrons. The turbulence damping results in electron acceleration and the generation of non-Maxwellian suprathermal tails on time scales short compared to collisional damping. Bulk heating also occurs if the fluctuating parallel electric field is strong enough. This study suggests that finite amplitude, low frequency, obliquely propagating, electromagnetic waves can play a significant role in the acceleration and heating of the solar corona electrons and in the coupling of medium and small-scale phenomena.

  12. Modeling of Outer Radiation Belt Electron Scattering due to Spatial and Spectral Properties of ULF Waves

    Science.gov (United States)

    Tornquist, Mattias

    The research presented in this thesis covers wave-particle interactions for relativistic (0.5-10 MeV) electrons in Earth's outer radiation belt (r = 3-7 RE, or L-shells: L = 3-7) interacting with magnetospheric Pc-5 (ULF) waves. This dissertation focuses on ideal models for short and long term electron energy and radial position scattering caused by interactions with ULF waves. We use test particle simulations to investigate these wave-particle interactions with ideal wave and magnetic dipole fields. We demonstrate that the wave-particle phase can cause various patterns in phase space trajectories, i.e. local acceleration, and that for a global electron population, for all initial conditions accounted for, has a negligible net energy scattering. Working with GSM polar coordinates, the relevant wave field components are EL, Ephi and Bz, where we find that the maximum energy scattering is 3-10 times more effective for Ephi compared to EL in a magnetic dipole field with a realistic dayside compression amplitude. We also evaluate electron interactions with two coexisting waves for a set of small frequency separations and phases, where it is confirmed that multi-resonant transport is possible for overlapping resonances in phase space when the Chirikov criterion is met (stochasticity parameter K = 1). The electron energy scattering enhances with decreasing frequency separation, i.e. increasing K, and is also dependent on the phases of the waves. The global acceleration is non-zero, can be onset in about 1 hour and last for > 4 hours. The adiabatic wave-particle interaction discussed up to this point can be regarded as short-term scattering ( tau ˜ hours ). When the physical problem extends to longer time scales (tau ˜ days ) the process ceases to be adiabatic due to the introduction of stochastic element in the system and becomes a diffusive process. We show that any mode in a broadband spectrum can contribute to the total diffusion rate for a particular drift

  13. MAN-MADE RADIONUCLIDES IN THE NEAR-THE-GROUND ATMOSPHERIC LAYER DUE TO THE FUKUSHIMA ACCIDENT

    Directory of Open Access Journals (Sweden)

    V. G. Bulgakov

    2011-01-01

    Full Text Available The article presents information about the main observation results of radiometric departments of the Federal Service for Hydrometeorology and Environmental Monitoring for changes in the radiation situation on the territory of Russia following the accident at the Fukushima NPP. The obtained experimental data allowed to conclude that the volumetric activities of radionuclides in the near-the-ground  atmospheric layer were by 3 to 6 orders of magnitude below the permissible volumetric activity set by Radiation Safety Standards (NRB-99/2009, and the correction to the density of soil contamination by cesium-137 was by 2 to 3 orders of magnitude less than the decrease of the density of contamination with this isotope of the global origin due to radioactive decay.

  14. Atmospheric hydroxyl radical production from electronically excited NO2 and H2O.

    Science.gov (United States)

    Li, Shuping; Matthews, Jamie; Sinha, Amitabha

    2008-03-21

    Hydroxyl radicals are often called the "detergent" of the atmosphere because they control the atmosphere's capacity to cleanse itself of pollutants. Here, we show that the reaction of electronically excited nitrogen dioxide with water can be an important source of tropospheric hydroxyl radicals. Using measured rate data, along with available solar flux and atmospheric mixing ratios, we demonstrate that the tropospheric hydroxyl contribution from this source can be a substantial fraction (50%) of that from the traditional O(1D) + H2O reaction in the boundary-layer region for high solar zenith angles. Inclusion of this chemistry is expected to affect modeling of urban air quality, where the interactions of sunlight with emitted NOx species, volatile organic compounds, and hydroxyl radicals are central in determining the rate of ozone formation.

  15. Electric Currents and Fields in Middle and Low Atmosphere in Fair-Weather Regions due to Distant Thunderstorms

    Science.gov (United States)

    Velinov, Peter; Velinov, Peter; Tonev, Peter

    The electric currents created by the thunderstorms and the electrified shower clouds over the Earth flow into the global atmospheric electric circuit and are responsible for the formation in fair-weather regions of ionosphere-ground current of about 2 pA per square meter, as well as for the related fair-weather electric field of the order of 100 V/m at sea level. The link of the diurnal variations of the fair-weather electric field with the global thunderstorm activity has been widely studied with connection to the Wilson's hypothesis. To confirm this hypothesis directly, also the fair-weather electric field response to a strong single lightning discharge has being examined. Here we study theoretically the variations of the electric currents and fields in fair-weather regions at different altitudes of the lower and middle atmosphere, which are provoked by distant lightning discharges. The electric field variations can play an important role at higher altitudes (in the upper troposphere and above), where they are much larger and possibly influence the physical and chemical processes. For our goals we realize a globalscale model of the electric fields and currents generated by a lightning discharge, which is based on the Maxwell's equations. The fair-weather electric characteristics are studied by our model depending on the lightning parameters, location and distance. We also examine how variations of the conductivity in the strato/mesosphere due to changes of solar and geomagnetic activity affect the characteristics studied. Another question discussed is whether and how the mesospheric electric response to a remote lightning discharge is influenced by the conductivity anisotropy above 70 km and by the geomagnetic field geometry. The variations of the fairweather electric fields due to a distant lightning at tropospheric heights are also studied with respect to their presumable role in the cloud physics.

  16. The Atmospheric Remote-sensing Infrared Exoplanets Large-survey (ARIEL) payload electronic subsystems

    Science.gov (United States)

    Focardi, M.; Pace, E.; Colomé, J.; Ribas, I.; Rataj, M.; Ottensamer, R.; Farina, M.; Di Giorgio, A. M.; Wawer, P.; Pancrazzi, M.; Noce, V.; Pezzuto, S.; Morgante, G.; Artigues, B.; Sierra-Roig, C.; Gesa, L.; Eccleston, P.; Crook, M.; Micela, G.

    2016-07-01

    The ARIEL mission has been proposed to ESA by an European Consortium as the first space mission to extensively perform remote sensing on the atmospheres of a well defined set of warm and hot transiting gas giant exoplanets, whose temperature range between ~600 K and 3000 K. ARIEL will observe a large number (~500) of warm and hot transiting gas giants, Neptunes and super-Earths around a range of host star types using transit spectroscopy in the ~2-8 μm spectral range and broad-band photometry in the NIR and optical. ARIEL will target planets hotter than 600 K to take advantage of their well-mixed atmospheres, which should show minimal condensation and sequestration of high-Z materials and thus reveal their bulk and elemental composition. One of the major motivations for exoplanet characterisation is to understand the probability of occurrence of habitable worlds, i.e. suitable for surface liquid water. While ARIEL will not study habitable planets, its major contribution to this topic will results from its capability to detect the presence of atmospheres on many terrestrial planets outside the habitable zone and, in many cases, characterise them. This represents a fundamental breakthrough in understanding the physical and chemical processes of a large sample of exoplanets atmospheres as well as their bulk properties and to probe in-space technology. The ARIEL infrared spectrometer (AIRS) provides data on the atmospheric composition; these data are acquired and processed by an On-Board Data Handling (OBDH) system including the Cold Front End Electronics (CFEE) and the Instrument Control Unit (ICU). The Telescope Control Unit (TCU) is also included inside the ICU. The latter is directly connected to the Control and Data Management Unit (CDMU) on board the Service Module (SVM). The general hardware architecture and the application software of the ICU are described. The Fine Guidance Sensor (FGS) electronics and the Cooler Control Electronics are also presented.

  17. Differential flux measurement of atmospheric pion, muon, electron and positron energy spectra at balloon altitudes

    Energy Technology Data Exchange (ETDEWEB)

    Grimani, C.; Brunetti, M.T.; Codino, A. [Perugia Univ. (Italy)]|[INFN, Perugia (Italy); Papini, P.; Massimo Brancaccio, F.; Finetti, N. [Florence Univ. (Italy)]|[INFN, Florence (Italy); Stephens, S.A. [Tata Institute of Fundamental Researc, Bombay (International Commission on Radiation Units and Measurements); Basini, G.; Bongiorno, F. [INFN, Laboratori Nazionali di Frascati, Rome (Italy); Golden, R.L. [New Mexico State Univ. Las Cruces, NM (United States). Particle Astrophysics Lab.

    1995-09-01

    The fluxes of atmospheric electrons, positrons, positive and negative muons and negative pions have been determined using the NMSU Wizard-MASS2 balloons-borne instrument. The instrument was launched from Fort Sumner, New Mexico, (geomagnetic cut-off about 4.5 GV/c) on september 23, 1991. The flight lasted 9.8 hours and remained above 100.000 ft. Muons and negative pions were observed and their momenta were determined. Since these particles are not a part of the primary component, the measurement of their fluxes provides information regarding production and propagation of secondary particles in the atmosphere. Similarly, observations of electrons and positrons well below the geomagnetic cut-off provides insight into electromagnetic cascade processes in the upper atmosphere. In addition, the determination of the energy spectra of rare particles such as positrons can be used for background subtraction for cosmic ray experiments gathering data below a few g/cm{sup 2} of overlying atmosphere.

  18. Watching the wind: seismic data contamination at long-periods due to atmospheric pressure-field-induced tilting

    Science.gov (United States)

    de Angelis, S.; Bodin, P.; Hagel, K.; Fletcher, D.

    2010-12-01

    Long-period noise generated by the elastic response of the Earth to atmospheric pressure fluctuations has long been recognized as a limiting factor for seismic investigations. The quality of seismic data recorded by sensitive, near-surface broadband seismometers can be severely corrupted by this effect. During the recent installation of a new broadband site on the Olympic Peninsula in Washington, the Pacific Northwest Seismic Network recorded and investigated elevated daytime noise levels at periods exceeding 30 seconds. Substantial power spectral density variations of the background noise field, 15-20 dB, were observed in the horizontal component seismograms. The pattern of the long-period noise exhibited striking correlations with local fluctuations of the air temperature and wind speed as measured nearby the seismic station by the National Weather Service Forecast Office, Seattle, Washington, and the National Oceanic and Atmospheric Administration. Several past studies have demonstrated that local wind systems may lead to variations of the atmospheric pressure field that deform the ground and perturb seismograms. The rotational component of this motion is detected by horizontal-component seismometers because at periods longer than the sensor’s low corner frequency the sensor is acting essentially as a tiltmeter. We obtained a transfer function that describes the response of the broadband seismometer to a tilt step change and estimated the amplitude of tilt noise to be on the order of 10-9 - 10-8 radians. Within the seismic pass-band of the sensor, it is not possible to remove the tilt signal from the observed seismograms because the details of the tilting depend on the pressure field variations, the compliance of the near surface to pressure variations, and the design and construction of the seismometer vault itself. At longer periods, using the seismic data to recover tilts of tectonic origin is made challenging because of the needed instrument correction

  19. Electron spin relaxation due to reorientation of a permanent zero field splitting tensor.

    Science.gov (United States)

    Schaefle, Nathaniel; Sharp, Robert

    2004-09-15

    Electron spin relaxation of transition metal ions with spin S> or =1 results primarily from thermal modulation of the zero field splitting (zfs) tensor. This occurs both by distortion of the zfs tensor due to intermolecular collisions and, for complexes with less than cubic symmetry, by reorientational modulation of the permanent zfs tensor. The reorientational mechanism is much less well characterized in previous work than the distortional mechanism although it is an important determinant of nuclear magnetic resonance (NMR) paramagnetic relaxation enhancement phenomena (i.e., the enhancement of NMR relaxation rates produced by paramagnetic ions in solution or NMR-PRE). The classical density matrix theory of spin relaxation does not provide an appropriate description of the reorientational mechanism at low Zeeman field strengths because the zero-order spin wave functions are stochastic functions of time. Using spin dynamics simulation techniques, the time correlation functions of the spin operators have been computed and used to determine decay times for the reorientational relaxation mechanism for S=1. In the zfs limit of laboratory field strengths (H(Zeem)spin decay is exponential, the spin relaxation time, tau(S) (composite function) approximately 0.53tau(R)((1)), where tau(R)((1)) is the reorientational correlation time of a molecule-fixed vector. The value of tau(S) (composite function) is independent of the magnitude of the cylindrical zfs parameter (D), but it depends strongly on low symmetry zfs terms (the E/D ratio). Other spin dynamics (SD) simulations examined spin decay in the intermediate regime of field strengths where H(Zeem) approximately H(zfs) (composite function), and in the vicinity of the Zeeman limit. The results demonstrate that the reorientational electron spin relaxation mechanism is often significant when H(zfs) (composite function)> or =H(Zeem), and that its neglect can lead to serious errors in the interpretation of NMR-PRE data.

  20. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    Science.gov (United States)

    Talman, Richard; Malitsky, Nikolay; Stulle, Frank

    2009-01-01

    -21, MOCOS05, available at http://www.JACoW.org], a code with similar capabilities. For this comparison an appropriately new, 50 MeV, “standard chicane” is introduced. Unlike CSRTrack (which neglects vertical forces) the present simulation shows substantial growth of vertical emittance. But “turning off” vertical forces in the UAL code (to match the CSRTrack treatment) brings the two codes into excellent agreement. (iii) Results are also obtained for 5 GeV electrons passing through a previously introduced “standard chicane” [Coherent Synchrotron Radiation, CSR Workshop, Berlin 2002, http://www.desy.de/csr] [of the sort needed for linear colliders and free electron lasers (FEL’s) currently under design or construction]. Relatively little emittance growth is predicted for typical bunch parameters at such high electron energy. Results are obtained for both round beams and ribbon beams (like those actually needed in practice). Little or no excess emittance growth is found for ribbon bunches compared to round bunches of the same charge and bunch width. The UAL string space charge formulation (like TraFic4 and CSRTrack) avoids the regularization step (subtracting the free-space space charge force) which is required (to remove divergence) in some methods. Also, by avoiding the need to calculate a retarded-time, four-dimensional field history, the computation time needed for realistic bunch evolution calculations is modest. Some theories of bunch dilution, because they ascribe emittance growth entirely to CSR, break down at low energy. In the present treatment, as well as CSR, all free-space Coulomb and magnetic space charge forces (but not image forces), and also the centrifugal space charge force (CSCF) are included. Charge-dependent beam steering due to CSCF, as observed recently by Beutner et al. [B. Beutner , in Proceedings of FEL Conference, BESSY, Berlin, Germany, 2006, MOPPH009], is also investigated.

  1. [Spatial distribution of electrons with high energy in atmospheric pressure glow discharge excited by DC voltage].

    Science.gov (United States)

    Liu, Zhi-qiang; Jia, Peng-ying; Liu, Tie

    2013-09-01

    Atmospheric pressure glow discharge excited by a DC voltage was realized in a 6 mm air gap by using a needle-water electrode discharge device. The atompheric pressure glow discharge has characteristic regions such as a cathode fall, a negative glow, a Faraday dark space, a positive column and an anode glow. The discharge is a normal glow through analyzing its voltage-current curve. The emission intensity of 337.1 nm spectral line from the second positive system of N2 was investigated because it can indicate the electron density with high energy. Results show that the maxima of high energy electrons appears in the vicinity of the needle tip, and it almost remains constant at other locations. The density of high energy electrons decreases with increasing the voltage. Similarly, it decreases with increasing the value of the ballast resistor. Oxygen atom is important for the sterilization and disinfection. The distribution of oxygen atom was also investigated by optical emission spectroscopy. It was found that the oxygen distribution is similar with the distribution of high energy electrons. These results are important for the application of atmospheric pressure glow discharge in environmental protection and biological treatment.

  2. Prompt enhancement of the Earth's outer radiation belt due to substorm electron injections

    Science.gov (United States)

    Tang, C. L.; Zhang, J.-C.; Reeves, G. D.; Su, Z. P.; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.; Wygant, J. R.

    2016-12-01

    We present multipoint simultaneous observations of the near-Earth magnetotail and outer radiation belt during the substorm electron injection event on 16 August 2013. Time History of Events and Macroscale Interactions during Substorms A in the near-Earth magnetotail observed flux-enhanced electrons of 300 keV during the magnetic field dipolarization. Geosynchronous orbit satellites also observed the intensive electron injections. Located in the outer radiation belt, RBSP-A observed enhancements of MeV electrons accompanied by substorm dipolarization. The phase space density (PSD) of MeV electrons at L* 5.4 increased by 1 order of magnitude in 1 h, resulting in a local PSD peak of MeV electrons, which was caused by the direct effect of substorm injections. Enhanced MeV electrons in the heart of the outer radiation belt were also detected within 2 h, which may be associated with intensive substorm electron injections and subsequent local acceleration by chorus waves. Multipoint observations have shown that substorm electron injections not only can be the external source of MeV electrons at the outer edge of the outer radiation belt (L* 5.4) but also can provide the intensive seed populations in the outer radiation belt. These initial higher-energy electrons from injection can reach relativistic energy much faster. The observations also provide evidence that enhanced substorm electron injections can explain rapid enhancements of MeV electrons in the outer radiation belt.

  3. Renormalization of transition matrix elements of particle number operators due to strong electron correlation

    Energy Technology Data Exchange (ETDEWEB)

    Fukushima, Noboru, E-mail: noboru.fukushima@gmail.com [Motomachi 13-23, Sanjo, Niigata 955-0072 (Japan)

    2011-02-18

    Renormalization of non-magnetic and magnetic impurities due to electron double-occupancy prohibition is derived analytically by an improved Gutzwiller approximation. Non-magnetic impurities are effectively weakened by the same renormalization factor as that for the hopping amplitude, whereas magnetic impurities are strengthened by the square root of the spin-exchange renormalization factor, in contrast to results by the conventional Gutzwiller approximation. We demonstrate it by showing that transition matrix elements of number operators between assumed excited states and between an assumed ground state and excited states are renormalized differently than diagonal matrix elements. Deviation from such simple renormalization with a factor is also discussed. In addition, as a related calculation, we correct an error in treatment of the renormalization of charge interaction in the literature. Namely, terms from the second order of the transition matrix elements are strongly suppressed. Since all these results do not depend on the signs of impurity potential or the charge interaction parameter, they are valid both in attractive and repulsive cases.

  4. Renormalization of the hydrogen sulfide properties due to the strong electron-phonon interaction

    Science.gov (United States)

    Kudryashov, N. A.; Kutukov, A. A.; Mazur, E. A.

    2017-01-01

    The normal state of a metal is described by generalized Eliashberg theory which takes into account the finite width of an electron band, strong electron-phonon coupling and electron-hole nonequivalence. Reconstructed parameters of the conduction band of the metallic hydrogen sulfide for both the real and imaginary parts of the mass renormalization of the electron Green’s function and the real and imaginary parts of the renormalization of the chemical potential have been found.

  5. The effect of seed electrons on the repeatability of atmospheric pressure plasma plume propagation: I. Experiment

    Science.gov (United States)

    Nie, L.; Chang, L.; Xian, Y.; Lu, X.

    2016-09-01

    One of the significant differences between the traditional streamers and the plasma jets is the repeatability of their propagation. In this paper, the effect of the seed electron density on the repeatability of the plasma jets is investigated. The seed electron density plays an essential role in the propagation of plasma plume which is in either repeatable mode or random mode depending on the frequency of the applied voltage and the mixture percentage of the working gas. By measuring the propagation velocities and the ignition delay time, it is found that the propagation velocities of the plasma plume are independent of the seed electron density. However, the jitter of the ignition delay time strongly depends on the frequency of the applied voltage and the mixture percentage of the working gas. After detailed analyzing of the experiment results, it is concluded that the minimum seed electron density required for the plasma bullet to propagate in repeatable mode is on the order of 108 cm-3 for gas pressure of 2 × 104 Pa. The minimum required seed electron density for the gas pressure of 4 × 103 Pa is on the order of 107 cm-3. Further analysis shows that, at one atmospheric pressure, the required minimum seed electron density for repeatable mode is on the order of 109 cm-3.

  6. Energy shift of H-atom electrons due to Gibbons-Hawking thermal bath

    CERN Document Server

    Pardy, Miroslav

    2016-01-01

    The electromagnetic shift of energy levels of H-atom electrons is determined by calculating an electron coupling to the Gibbons-Hawking electromagnetic field thermal bath. Energy shift of electrons in H-atom is determined in the framework of the non-relativistic quantum mechanics.

  7. Modification of surface layers of copper under the action of the volumetric discharge initiated by an avalanche electron beam in nitrogen and CO2 at atmospheric pressure

    Science.gov (United States)

    Shulepov, M. A.; Akhmadeev, Yu. Kh.; Tarasenko, V. F.; Kolubaeva, Yu. A.; Krysina, O. V.; Kostyrya, I. D.

    2011-05-01

    The results of experimental investigations of the action of the volumetric discharge initiated by an avalanche electron beam on the surface of copper specimens are presented. The volumetric (diffuse) discharge in nitrogen and CO2 at atmospheric pressure was initiated by applying high voltage pulses of nanosecond duration to a tubular foil cathode. It has been found that the treatment of a copper surface by this type of discharge increases the hardness of the surface layer due to oxidation.

  8. Target heating due to the shock produced hot electrons in the shock ignition scheme

    Science.gov (United States)

    Rezaei, Somayeh; Farahbod, Amir Hossein; Jafari, Mohammad Jafar; Sobhanian, Samad

    2016-09-01

    Hot electrons are produced as a result of ignitor-corona interaction of the shock ignition scheme. In the present paper, penetration depth and energy deposition of such energetic electrons have been qualitatively discussed applying Monte Carlo simulations. Target real conditions for propagating hot electrons were taken from 1-D hydrodynamic simulations. It has been found that compressing target up to 10.4 ns helps to stop hot electrons at a proper distance thus, preventing fuel preheating. In addition, embedding hot electron energy source into the hydrodynamic code, changes of parameters p, ρ and ρR are calculated. Monoenergetic electron beams have been launched at different times of target compression. The simulation results indicate the creation of high ablation pressure as well as maximum shell areal density by a 50 keV monoenergetic electron beam with intensity 1 PW/cm2 irradiated on the compressed target at a proper time which indeed improves the implosion processes.

  9. Electron-ion dissociative recombination rate constants relevant to the Titan atmosphere and the Interstellar Medium

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, David; Lawson, Patrick; Adams, Nigel, E-mail: ngadams@uga.edu [University of Georgia, Department of Chemistry, 101 Cedar St., Athens, Georgia 30602 (United States)

    2014-01-21

    Following the arrival of Cassini at Titan in 2004, the Titan atmosphere has been shown to contain large complex polycyclic-aromatic hydrocarbons. Since Cassini has provided a great deal of data, there exists a need for kinetic rate data to help with modeling this atmosphere. One type of kinetic data needed is electron-ion dissociative recombination (e-IDR) rate constants. These data are not readily available for larger compounds, such as naphthalene, or oxygen containing compounds, such as 1,4 dioxane or furan. Here, the rate constants for naphthalene, 1,4 dioxane, and furan have been measured and their temperature dependencies are determined when possible, using the University of Georgia's Variable Temperature Flowing Afterglow. The rate constants are compared with those previously published for other compounds; these show trends which illustrate the effects which multi-rings and oxygen heteroatoms substitutions have upon e-IDR rate constants.

  10. Ionisation in atmospheres of Brown Dwarfs and extrasolar planets I The role of electron avalanche

    CERN Document Server

    Helling, Ch; Witte, S; Diver, D A

    2010-01-01

    Brown Dwarf and extrasolar planet atmospheres form clouds which strongly influence the local chemistry and physics. These clouds are globally neutral obeying dust-gas charge equilibrium which is, on short time scales, inconsistent with the observation of stochastic ionisation events of the solar system planets. We argue that a significant volume of the clouds in Brown Dwarfs and extrasolar planets is susceptible to local discharge events. These are electron avalanches triggered by charged dust grains. Such intra-cloud discharges occur on time scales shorter than the time needed to neutralise the dust grains by collisional processes. An ensemble of discharges is likely to produce enough free charges to suggest a partial and stochastic coupling of the atmosphere to a large-scale magnetic field.

  11. Secondary electron emission from a charged spherical dust particle due to electron incidence according to OML model

    Energy Technology Data Exchange (ETDEWEB)

    Tomita, Y., E-mail: tomita@swip.ac.cn [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, Sichuan (China); Huang, Z.H.; Pan, Y.D. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, Sichuan (China); Kawamura, G. [National Institute for Fusion Science, Toki 509-5292 (Japan); Yan, L.W. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, Sichuan (China)

    2015-08-15

    Effect of secondary electron emission (SEE) current to dust charging and influence to forces on a dust particle are studied according to the orbital motion limited (OML) model. As higher electron temperature increases the SEE current, the negative dust charge decreases. As a result, the ion friction force on the dust particle decreases. The critical electron temperatures without the dust charge are 75.1, 70.3 and 55.9 eV for graphite and are 31.3, 30.4 and 27.1 eV for tungsten to the temperature ratio T{sub i}/T{sub e} = 0.1, 1.0 and 10.0, respectively. At the critical electron temperature, there is no ion scattering force but the ion absorption force remains finite.

  12. The ion potential in warm dense matter: wake effects due to streaming degenerate electrons

    CERN Document Server

    Moldabekov, Zhandos; Bonitz, Michael; Ramazano, Tlekkabul

    2014-01-01

    The effective dynamically screened potential of a classical ion in a stationary flowing quantum plasma at finite temperature is investigated. This is a key quantity for thermodynamics and transport of dense plasmas in the warm dense matter regime. To compute this potential a linear response description of the electrons via the Mermin dielectric function is utilized with electron-electron collisions taken into account via a relaxation time approximation. The ion potential strongly deviates from the static Yukawa potential exhibiting the familiar oscillatory structure with attractive minima (wake potential). This potential is analyzed in detail for high-density plasmas with values of the Brueckner parameter in the range $0.1 \\le r_s \\le 1$, for a broad range of plasma temperature and electron streaming velocity. It is shown that wake effects become weaker with increasing temperature of the electrons. Finally, we obtain the minimal electron streaming velocity for which attraction between ions occurs. This veloci...

  13. [Research on electron density in DC needle-plate corona discharge at atmospheric pressure].

    Science.gov (United States)

    Liu, Zhi-Qiang; Guo, Wei; Liu, Tao-Tao; Wu, Wen-Shuo; Liu, Shu-Min

    2013-11-01

    Using needle-plate discharge device, corona discharge experiment was done in the atmosphere. Through photo of spot size of light-emitting area, the relationship between the voltage and thickness of corona layer was discussed. When the distance between tip and plate is fixed, the thickness of corona layer increases with the increase in voltage; when the voltage is fixed, the thickness of corona layer decreases with the increase in the distance between tip and plate. As spectral intensity of N2 (C3pi(u)) (337.1 nm)reflects high energy electron density, it was measured with emission spectrometry. The results show that high energy electron density is the biggest near the needle tip and the relationship between high energy electron density and voltage is basically linear increasing. Fixing voltage, high energy electron density decreases with the increase in the distance between tip and plate. When the voltage and the distance between tip and plate are fixed, the high energy electron density increases with the decrease in the curvature radius of needle tip. These results are of great importance for the study of plasma parameters of corona discharge.

  14. The effect of seed electrons on the repeatability of atmospheric pressure plasma plume propagation. II. Modeling

    Science.gov (United States)

    Chang, L.; Nie, L.; Xian, Y.; Lu, X.

    2016-12-01

    One of the distinguishable features of plasma jets compared with the traditional streamers is their repeatable propagation. As an initial objective, the effect of seed electrons on the repeatability of plasma plume propagation is investigated numerically. Besides residual electrons left from previous pulses, the electrons detached from O2 - ions could also be a significant source of the seed electrons to affect the repeatability of plasma plume propagation when an electronegative gas admixture is presented. In this investigation, a global plasma chemical kinetics model is developed to investigate the temporal evolution of the electron and O2 - ions in the afterglow of a plasma plume driven by microsecond pulse direct current voltages, at a total gas pressure of 2 × 104 Pa or 4 × 103 Pa in helium or helium-oxygen mixtures with an air impurity of 0.025%. In addition, a Monte Carlo technique has been applied to calculate the O2 - detachment rate coefficient. Accordingly, the seed electron density due to detachment from O2 - ions for different percentages of oxygen is obtained. Finally, the minimum seed electron density required for the plasma bullets to propagate in a repeatable mode is obtained according to the critical frequency from the experiments. It is found that the order of minimum seed electron number density required for repeatable propagation mode is independent of oxygen concentrations in the helium-oxygen mixture. It is 10 8 cm - 3 for 20 kPa and 10 7 cm - 3 for 4 kPa. Furthermore, for the helium with an air impurity of 0.025%, the residual electrons left over from previous discharges are the main source of seed electrons. On the other hand, when 0.5% of O2 is added, the detachment of O2 - is the main source of the seed electrons.

  15. Electron Density and Temperature Measurements, and Abundance Anomalies in the Solar Atmosphere

    Indian Academy of Sciences (India)

    Anita Mohan; Bhola N. Dwivedi; Enrico Landi

    2000-09-01

    Using spectra obtained from the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph on the spacecraft SOHO (Solar and Heliospheric Observatory), we investigate the height dependence of electron density, temperature and abundance anomalies in the solar atmosphere. In particular, we present the behaviour of the solar FIP effect (the abundance enhancement of elements with first ionization potential < 10 eV in the corona with respect to photospheric values) with height above an active region observed at the solar limb, with emphasis on the so-called transition region lines.

  16. Determination of the atmospheric optical depth due to the El Chichon stratospheric aerosol cloud in the polluted atmosphere of Mexico City

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, Ignacio [Centro Universitario de Investigaciones en Ciencia del Ambiente, Universidad de Colima, Colima, Colima, (Mexico); Kondratyev, Kirill Ya. [Academician, Counsellor Center for Ecological Safety, Russian Academy of Sciences, St. Petersburg (Russian Federation); Zenteno, Gerardo [Instituto de Geofisica, UNAM, Mexico, D.F. (Mexico)

    1996-01-01

    Direct solar radiation measurements were used to determine the aerosol optical depth (AOD) increase associated with the presence of aerosol and large particles (ash) originating from the 28 March to 4 April 1982 El Chichon eruptions (17.5 degrees N, 93.3 degrees W; Mexico) on Mexico City's polluted atmospheric aerosol layer. The results are compared with those obtained at Vancouver, British Columbia, revealing that a first AOD increase occurred in both locations during May, June, and July 1982, the Mexico City AOD decay is more extended, not reaching normal climatological values until February 1983. Meanwhile, Vancouver's AOD reached minimum values in September 1982, which subsequently increased over a period from October 1982 to September 1983. This secondary maximum was recorded in Mexico City from March to August 1983. Results suggest that the first AOD increases in May, June and July 1982, both at Vancouver and Mexico City, are due chiefly to short life-time volcanic ash particles being located near the surface. However, the second AOD increases, associated with anomalously colored twilights, corresponds to stratospheric volcanic aerosols. [Spanish] Se utilizaron mediciones de radiacion solar directa para determinar el incremento de la profundidad optica del aerosol (AOD) asociada a la presencia de aerosoles y particulas grandes (cenizas) organizadas por las erupciones de El Chichon (17.5 grados N, 93.3 grados W; Mexico) del 28 de marzo al 4 de abril de 1982 sobre la capa atmosferica contaminada de la Ciudad de Mexico. Los resultados se comparan con los obtenidos en Vancouver, Colombia Britanica, relevando que un primer aumento de AOD ocurrio en ambos lugares durante mayo, junio y julio de 1982. Sin embargo, la AOD decayo en Ciudad de Mexico mas lentamente, alcanzando los valores climatologicos normales hasta febrero de 1983. Mientras tanto la AOD para Vancouver alcanzo valores minimos en septiembre de 1982; estos subsecuentemente se incrementaron en

  17. TEC Enhancement due to Energetic Electrons Above Taiwan and the West Pacific

    Directory of Open Access Journals (Sweden)

    Alla V. Suvorova

    2013-01-01

    Full Text Available The energetic electrons of the inner radiation belt during a geomagnetic disturbance can penetrate in the forbidden range of drift shells located at the heights of the topside equatorial ionosphere (< 1000 km. A good correlation was previously revealed between positive ionospheric storms and intense fluxes of quasi-trapped 30-keV electrons at ~900 km height in the forbidden zone. In the present work, we use statistics to validate an assumption that the intense electron fluxes in the topside equatorial ionosphere can be an important source of the ionization in the low-latitude ionosphere. The data on the energetic electrons were obtained from polar orbiting satellites over the periods of the 62 strong geomagnetic storms from 1999 to 2006. Ionospheric response to the selected storms was determined using global ionospheric maps of vertical total electron content (VTEC. A case-event study of a major storm on 9 November 2004 provided experimental evidence in support to the substantial ionization effect of energetic electrons during positive ionospheric storms at the low latitudes. Statistical analysis of nine magnetic storms indicated that the VTEC increases coincided with and coexisted with intense 30-keV electron fluxes irrespective of local time and phase of geomagnetic storm. We concluded that extremely intense fluxes of the 30-keV electrons in the topside low-latitude ionosphere can contribute ~ 10 - 30 TECU to the localized positive ionospheric storms.

  18. Evidence of locally enhanced target heating due to instabilities of counter-streaming fast electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Koester, Petra; Cecchetti, Carlo A. [Intense Laser Irradiation Laboratory at INO, CNR, Pisa (Italy); Booth, Nicola; Woolsey, Nigel [Physics Department, University of York, York (United Kingdom); Chen, Hui [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Evans, Roger G. [Imperial College London, London (United Kingdom); Gregori, Gianluca; Li, Bin; Mithen, James; Murphy, Christopher D. [Physics Department, University of Oxford, Oxford (United Kingdom); Labate, Luca; Gizzi, Leonida A. [Intense Laser Irradiation Laboratory at INO, CNR, Pisa (Italy); INFN, Sezione di Pisa, Pisa (Italy); Levato, Tadzio [Intense Laser Irradiation Laboratory at INO, CNR, Pisa (Italy); University of Rome Tor Vergata, Rome (Italy); Makita, Mikako; Riley, David [Physics Department, Queens University Belfast, Belfast (United Kingdom); Notley, Margaret; Pattathil, Rajeev [Rutherford Appleton Laboratory, STFC, Didcot (United Kingdom)

    2015-02-15

    The high-current fast electron beams generated in high-intensity laser-solid interactions require the onset of a balancing return current in order to propagate in the target material. Such a system of counter-streaming electron currents is unstable to a variety of instabilities such as the current-filamentation instability and the two-stream instability. An experimental study aimed at investigating the role of instabilities in a system of symmetrical counter-propagating fast electron beams is presented here for the first time. The fast electron beams are generated by double-sided laser-irradiation of a layered target foil at laser intensities above 10{sup 19 }W/cm{sup 2}. High-resolution X-ray spectroscopy of the emission from the central Ti layer shows that locally enhanced energy deposition is indeed achieved in the case of counter-propagating fast electron beams.

  19. Reformed Solitary Kinetic Alfvén Waves due to Dissipations and Auroral Electron Acceleration

    Institute of Scientific and Technical Information of China (English)

    WU De-Jin; CHAO Jih-Kwin; LEE Luo-Chuan; FENG Xue-Shang

    2001-01-01

    The physical nature of the auroral electron acceleration has been an outstanding problem in space physics for decades.Some recent observations from the auroral orbit satellites,FREJA and FAST,showed that large amplitude solitary kinetic Alfvén waves (SKAWs) are a common electromagnetic active phenomenon in the auroral magnetosphere. In a Iow-ββ/2 (i.e.,β/2 < me/mi < 1) plasma,the drift velocity of electrons relative to ions within SKAWs is much larger than thermal velocities of both electrons and ions.This leads to instabilities and causes dissipations of SKAWs.In the present work,based on the analogy of classical particle motion in a potential well,it is shown that a shock-like structure can be formed from SKAWs if dissipation effects are included.The reformed SKAWs with a shock-like structure have a local density jump and a net field-aligned electric potential drop of order of mev2A/e over a characteristic width of several )e.As a consequence,the reformed SKAWs can efficiently accelerate electrons field-aligned to the order of the local Alfvén velocity.In particular,we argue that this electron acceleration mechanism by reformed SKAWs can play an important role in the auroral electron acceleration problem.The result shows that not only the location of acceleration regions predicted by this model is well consistent with the observed auroral electron acceleration region of I 2 RE above the auroral ionosphere,but also the accelerated electrons from this region can obtain an energy of several keV and carry a field-aligned current of several/A/m2 which are comparable to the observations of auroral electrons.

  20. SEPERATION OF IKONOS SENSOR’S ELECTRONIC NOISE FROM ATMOSPHERIC INDUCED EFFECTS

    Directory of Open Access Journals (Sweden)

    M. R. Mobashery

    2013-09-01

    Full Text Available The quality of satellite images has always been of particular importance in remote sensing. Signals received from satellite sensors include some signals other than those of target signal that may be classified totally as the atmospheric effect and the sensor induced noise. Separating non-target signals and attempting in removing them from images is essential. One method for measuring and removing non-target signals is that of atmospheric correction by Dark Object Subtraction (DOS. This method is based on the sensor’s output for the targets that should have almost zero reflectance in a given band. Next, the obtained value will be deducted from the remaining pixels values; regardless of the type of the sensors. Each Charge-Coupled Device (CCD has its own noise behavior; therefore, the amount deducted values from each pixel can be different for each CCD unit and type. Among the various noises of the CCD and their related electronic circuits, dark current noise, non-uniform pixels noise and read noise were selected to be studied in this paper. The data were obtained from multispectral sensor images of IKONOS. This sensor can provide images in two forms of Panchromatic (PAN and Multispectral (MS. The results of this study showed that the amount of dark object pixels and the total amount of CCD noises in each band are different. Separation of the noises introduced in this paper from the amount of dark object pixel values can result in an upgraded method for image atmosphere corrections.

  1. Projected changes in atmospheric heating due to changes in fire disturbance and the snow season in the western Arctic, 2003–2100

    Science.gov (United States)

    Euskirchen, E.S.; McGuire, Anthony; Rupp, T.S.; Chapin, F. S.; Walsh, J.E.

    2009-01-01

    In high latitudes, changes in climate impact fire regimes and snow cover duration, altering the surface albedo and the heating of the regional atmosphere. In the western Arctic, under four scenarios of future climate change and future fire regimes (2003–2100), we examined changes in surface albedo and the related changes in regional atmospheric heating due to: (1) vegetation changes following a changing fire regime, and (2) changes in snow cover duration. We used a spatially explicit dynamic vegetation model (Alaskan Frame-based Ecosystem Code) to simulate changes in successional dynamics associated with fire under the future climate scenarios, and the Terrestrial Ecosystem Model to simulate changes in snow cover. Changes in summer heating due to the changes in the forest stand age distributions under future fire regimes showed a slight cooling effect due to increases in summer albedo (mean across climates of −0.9 W m−2 decade−1). Over this same time period, decreases in snow cover (mean reduction in the snow season of 4.5 d decade−1) caused a reduction in albedo, and a heating effect (mean across climates of 4.3 W m−2 decade−1). Adding both the summer negative change in atmospheric heating due to changes in fire regimes to the positive changes in atmospheric heating due to changes in the length of the snow season resulted in a 3.4 W m−2 decade−1 increase in atmospheric heating. These findings highlight the importance of gaining a better understanding of the influences of changes in surface albedo on atmospheric heating due to both changes in the fire regime and changes in snow cover duration.

  2. Imprint of the atmospheric attenuation process on electron distribution in EAS

    Science.gov (United States)

    Dey, R. K.; Dam, S.; Ray, S.

    2016-09-01

    The lateral density distribution (LDD) of shower particles in an extensive air shower (EAS) experiment is commonly approximated by a particular type of lateral density function (LDF). A standard perception is being used in air shower physics since long, according to which the LDD is assumed to be symmetric about the EAS axis, and the adopted LDF is adequate for the description of the LDD. However, the simulated electron density of a non-vertical EAS is asymmetric. In this work, such asymmetry in the LDD can be qualitatively explained as the atmospheric attenuation suffered by each shower particle. Quantitatively, the asymmetry can be roughly described in terms of a gap length (GL) between the EAS core and the center of the modified density pattern consisting of several equi-density ellipses. This study also validates the use of such a modeling of the atmospheric attenuation on the electromagnetic component in an EAS by investigating the so called GL in simulated density data. A modified LDF is proposed, based on these features of the simulated densities for the purpose of shower reconstruction in EAS experiments. The GL arises from attenuation effect is found to increase with the mass of the shower initiating particle. A different radial dependence of the local age parameter (LAP) is seen, if the modified LDF is applied to simulated electron densities. Primary cosmic-ray mass sensitivity of the LAP is also re-examined.

  3. Imprint of the atmospheric attenuation process on electron distribution in EAS

    Science.gov (United States)

    Dey, R. K.; Dam, S.; Ray, S.

    2017-04-01

    The lateral density distribution (LDD) of shower particles in an extensive air shower (EAS) experiment is commonly approximated by a particular type of lateral density function (LDF). A standard perception is being used in air shower physics since long, according to which the LDD is assumed to be symmetric about the EAS axis, and the adopted LDF is adequate for the description of the LDD. However, the simulated electron density of a non-vertical EAS is asymmetric. In this work, such asymmetry in the LDD can be qualitatively explained as the atmospheric attenuation suffered by each shower particle. Quantitatively, the asymmetry can be roughly described in terms of a gap length (GL) between the EAS core and the center of the modified density pattern consisting of several equi-density ellipses. This study also validates the use of such a modeling of the atmospheric attenuation on the electromagnetic component in an EAS by investigating the so called GL in simulated density data. A modified LDF is proposed, based on these features of the simulated densities for the purpose of shower reconstruction in EAS experiments. The GL arises from attenuation effect is found to increase with the mass of the shower initiating particle. A different radial dependence of the local age parameter (LAP) is seen, if the modified LDF is applied to simulated electron densities. Primary cosmic-ray mass sensitivity of the LAP is also re-examined.

  4. Solvated electrons at the atmospheric pressure plasma-water anodic interface

    Science.gov (United States)

    Gopalakrishnan, R.; Kawamura, E.; Lichtenberg, A. J.; Lieberman, M. A.; Graves, D. B.

    2016-07-01

    We present results from a particle-in-cell/Monte Carlo model of a dc discharge in argon at atmospheric pressure coupled with a fluid model of an aqueous electrolyte acting as anode to the plasma. The coupled models reveal the structure of the plasma-electrolyte interface and near-surface region, with a special emphasis on solvated or hydrated electrons. Results from the coupled models are in generally good agreement with the experimental results of Rumbach et al (2016 Nat. Commun. 6 7248). Electrons injected from the plasma into the water are solvated, then lost by reaction with water within about 10-20 nm from the surface. The major reaction products are OH- and H2. The solvated electron density profile is controlled by the injected electron current density and subsequent reactions with water, and is relatively independent of the external plasma electric field and the salt concentration in the aqueous electrolyte. Simulations of the effects of added scavenger compounds (H2O2, \\text{NO}2- , \\text{NO}2- and H+) on near-surface solvated electron density generally match the experimental results. The generation of near-surface OH- following electron-water decomposition in the presence of bulk acid creates a highly basic region (pH ~ 11) very near the surface. In the presence of bulk solution acidity, pH can vary from a very acidic pH 2 away from the surface to a very basic pH 11 over a distance of ~200 nm. High near-surface gradients in aqueous solution properties could strongly affect plasma-liquid applications and challenge theoretical understanding of this complex region.

  5. Anomalously Hot Electrons due to Rescatter of Stimulated Raman Scattering in the Kinetic Regime

    CERN Document Server

    Winjum, B J; Tsung, F S; Mori, W B

    2012-01-01

    Using particle-in-cell simulations, we examine hot electron generation from electron plasma waves excited by stimulated Raman scattering and rescattering in the kinetic regime where the wavenumber times the Debye length (k\\lambda_D) is greater than 0.3 for backscatter. We find that for laser and plasma conditions of possible relevance to experiments at the National Ignition Facility (NIF), anomalously energetic electrons can be produced through the interaction of a discrete spectrum of plasma waves generated from SRS (back and forward scatter), rescatter, and the Langmuir decay of the rescatter-generated plasma waves. Electrons are bootstrapped in energy as they propagate into plasma waves with progressively higher phase velocities.

  6. Temperature Isotropization in Solar Flare Plasmas due to the Electron Firehose Instability

    CERN Document Server

    Messmer, P

    2002-01-01

    The isotropization process of a collisionless plasma with an electron temperature anisotropy along an external magnetic field ($T_\\| ^e\\gg T_\\perp^e$, $\\|$ and $\\perp$ with respect to the background magnetic field) and isotropic protons is investigated using a particle-in-cell(PIC) code. Restricting wave growth mainly parallel to the external magnetic field, the isotropization mechanism is identified to be the Electron Firehose Instability (EFI). The free energy in the electrons is first transformed into left-hand circularly polarized transverse low-frequency waves by a non-resonant interaction. Fast electrons can then be scattered towards higher perpendicular velocities by gyroresonance, leading finally to a complete isotropization of the velocity distribution. During this phase of the instability, Langmuir waves are generated which may lead to the emission of radio waves. A large fraction of the protons is resonant with the left-hand polarized electromagnetic waves, creating a proton temperature anisotropy ...

  7. Radial transport of radiation belt electrons due to stormtime Pc5 waves

    Directory of Open Access Journals (Sweden)

    A. Y. Ukhorskiy

    2009-05-01

    Full Text Available During geomagnetic storms relativistic electron fluxes in the outer radiation belt exhibit dynamic variability over multiple orders of magnitude. This requires radial transport of electrons across their drift shells and implies violation of their third adiabatic invariant. Radial transport is induced by the interaction of the electron drift motion with electric and magnetic field fluctuations in the ULF frequency range. It was previously shown that solar-wind driven ULF waves have long azimuthal wave lengths and thus can violate the third invariant of trapped electrons in the process of resonant interaction with their gradient-curvature motion. However, the amplitude of solar-wind driven ULF waves rapidly decreases with decreasing L. It is therefore not clear what mechanisms are responsible for fast transport rates observed inside the geosynchronous orbit. In this paper we investigate wether stormtime Pc5 waves can contribute to this process. Stormtime Pc5s have short azimuthal wave lengths and therefore cannot exhibit resonance with the the electron drift motion. However we show that stormtime Pc5s can cause localized random scattering of electron drift motion that violates the third invariant. According to our results electron interaction with stormtime Pc5s can produce rapid radial transport even as low as L≃4. Numerical simulations show that electron transport can exhibit large deviations from radial diffusion. The diffusion approximation is not valid for individual storms but only applies to the statistically averaged response of the outer belt to stormtime Pc5 waves.

  8. Subsecond spin relaxation times in quantum dots at zero applied magnetic field due to a strong electron-nuclear interaction.

    Science.gov (United States)

    Oulton, R; Greilich, A; Verbin, S Yu; Cherbunin, R V; Auer, T; Yakovlev, D R; Bayer, M; Merkulov, I A; Stavarache, V; Reuter, D; Wieck, A D

    2007-03-09

    A key to ultralong electron spin memory in quantum dots (QDs) at zero magnetic field is the polarization of the nuclei, such that the electron spin is stabilized along the average nuclear magnetic field. We demonstrate that spin-polarized electrons in n-doped (In,Ga)As/GaAs QDs align the nuclear field via the hyperfine interaction. A feedback onto the electrons occurs, leading to stabilization of their polarization due to formation of a nuclear spin polaron [I. A. Merkulov, Phys. Solid State 40, 930 (1998)]. Spin depolarization of both systems is consequently greatly reduced, and spin memory of the coupled electron-nuclear spin system is retained over 0.3 sec at temperature of 2 K.

  9. Ion potential in warm dense matter: wake effects due to streaming degenerate electrons.

    Science.gov (United States)

    Moldabekov, Zhandos; Ludwig, Patrick; Bonitz, Michael; Ramazanov, Tlekkabul

    2015-02-01

    The effective dynamically screened potential of a classical ion in a stationary flowing quantum plasma at finite temperature is investigated. This is a key quantity for thermodynamics and transport of dense plasmas in the warm-dense-matter regime. This potential has been studied before within hydrodynamic approaches or based on the zero temperature Lindhard dielectric function. Here we extend the kinetic analysis by including the effects of finite temperature and of collisions based on the Mermin dielectric function. The resulting ion potential exhibits an oscillatory structure with attractive minima (wakes) and, thus, strongly deviates from the static Yukawa potential of equilibrium plasmas. This potential is analyzed in detail for high-density plasmas with values of the Brueckner parameter in the range 0.1≤r(s)≤1 for a broad range of plasma temperature and electron streaming velocity. It is shown that wake effects become weaker with increasing temperature of the electrons. Finally, we obtain the minimal electron streaming velocity for which attraction between ions occurs. This velocity turns out to be less than the electron Fermi velocity. Our results allow for reliable predictions of the strength of wake effects in nonequilibrium quantum plasmas with fast streaming electrons showing that these effects are crucial for transport under warm-dense-matter conditions, in particular for laser-matter interaction, electron-ion temperature equilibration, and stopping power.

  10. Electron residual energy due to stochastic heating in field-ionized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Khalilzadeh, Elnaz [Department of Physics, Kharazmi University, 49 Mofateh Ave, Tehran (Iran, Islamic Republic of); The Plasma Physics and Fusion Research School, Tehran (Iran, Islamic Republic of); Yazdanpanah, Jam, E-mail: jamal.yazdan@gmail.com; Chakhmachi, Amir [The Plasma Physics and Fusion Research School, Tehran (Iran, Islamic Republic of); Jahanpanah, Jafar [Department of Physics, Kharazmi University, 49 Mofateh Ave, Tehran (Iran, Islamic Republic of); Yazdani, Elnaz [Laser and Optics Research School, Tehran (Iran, Islamic Republic of)

    2015-11-15

    The electron residual energy originated from the stochastic heating in under-dense field-ionized plasma is investigated here. Initially, the optical response of plasma is modeled by using two counter-propagating electromagnetic waves. In this case, the solution of motion equation of a single electron indicates that by including the ionization, the electron with higher residual energy compared with that without ionization could be obtained. In agreement with chaotic nature of the motion, it is found that the electron residual energy will be significantly changed by applying a minor change in the initial conditions. Extensive kinetic 1D-3V particle-in-cell simulations have been performed in order to resolve full plasma reactions. In this way, two different regimes of plasma behavior are observed by varying the pulse length. The results indicate that the amplitude of scattered fields in a proper long pulse length is high enough to act as a second counter-propagating wave and trigger the stochastic electron motion. On the contrary, the analyses of intensity spectrum reveal the fact that the dominant scattering mechanism tends to Thomson rather than Raman scattering by increasing the pulse length. A covariant formalism is used to describe the plasma heating so that it enables us to measure electron temperature inside and outside of the pulse region.

  11. Sources and sinks of atmospheric N2O and the possible ozone reduction due to industrial fixed nitrogen fertilizers

    Science.gov (United States)

    Liu, S. C.; Cicerone, R. J.; Donahue, T. M.; Chameides, W. L.

    1977-01-01

    The terrestrial and marine nitrogen cycles are examined in an attempt to clarify how the atmospheric content of N2O is controlled. We review available data on the various reservoirs of fixed nitrogen, the transfer rates between the reservoirs, and estimate how the reservoir contents and transfer rates can change under man's influence. It is seen that sources, sinks and lifetime of atmospheric N2O are not understood well. Based on our limited knowledge of the stability of atmospheric N2O we conclude that future growth in the usage of industrial fixed nitrogen fertilizers could cause a 1% to 2% global ozone reduction in the next 50 years. However, centuries from now the ozone layer could be reduced by as much as 10% if soils are the major source of atmospheric N2O.

  12. TEC enhancement due to energetic electrons above Taiwan and the West Pacific

    CERN Document Server

    Suvorova, A V; Dmitriev, A V

    2013-01-01

    The energetic electrons of the inner radiation belt during a geomagnetic disturbance can penetrate in the forbidden range of drift shells located at the heights of the topside equatorial ionosphere (<1000 km). A good correlation was previously revealed between positive ionospheric storms and intense fluxes of quasi-trapped 30-keV electrons at ~900 km height in the forbidden zone. In the present work, we use statistics to validate an assumption that the intense electron fluxes in the topside equatorial ionosphere can be an important source of the ionization in the low-latitude ionosphere. The data on the energetic electrons were obtained from polar orbiting satellites over the periods of the 62 strong geomagnetic storms from 1999 to 2006. Ionospheric response to the selected storms was determined using global ionospheric maps of vertical total electron content (VTEC). A case-event study of a major storm on 9 November 2004 provided experimental evidence in support to the substantial ionization effect of ener...

  13. Internal Electron Transport Barrier due to Neoclassical Ambipolarity in the HSX Stellarator

    Science.gov (United States)

    Lore, Jeremy

    2009-11-01

    Strongly peaked electron temperature profiles are measured in the core of the Helically Symmetric Experiment (HSX) during electron cyclotron heating; with central temperatures of 2.5keV for 100kW of injected power. These measurements, coupled with neoclassical predictions of large ``electron root'' radial electric fields with strong radial shear, are evidence of a neoclassically driven thermal transport barrier. Neoclassical transport is analyzed using the PENTA code [1], in which parallel momentum is conserved. Momentum conservation, including the effects of parallel flow, has long been known to be important in tokamak neoclassical calculations. Conventional stellarators, on the other hand, typically exhibit strong flow damping in all directions on a flux surface, and the parallel flows can be neglected. In this case, the radial electric field is calculated using a simple ambipolarity constraint: setting the ion flux equal to the electron flux. In stellarators with very low effective ripple, such as HSX, parallel flow and momentum conservation are again expected to be important. Large parallel flow measurements (˜20km/s) from the ChERS diagnostic are consistent with reduced damping in the direction of symmetry. In addition to neoclassical transport, a model of Trapped Electron Mode turbulence is used to calculate the turbulent-driven electron thermal diffusivity. The very peaked Te profile is reproduced by predictive transport simulations only when turbulent transport quenching via sheared ExB flow is included [2]. ChERS measurements of the radial electric field profile and comparison to the neoclassical calculations will also be presented.[4pt] [1] D.A. Spong, Phys. Plasmas 12, 056114 (2005).[0pt] [2] W. Guttenfelder, J. Lore, et. al, Phys. Rev. Lett. 101, 215002 (2008).

  14. Magnification variations due to illumination curvature and object defocus in transmission electron microscopy

    Science.gov (United States)

    van Duinen, Gijs; van Heel, Marin; Patwardhan, Ardan

    2005-10-01

    It has previously been shown that - in theory - magnification variations can occur in an imaging system as a function of defocus, depending on the field curvature of the illuminating system. We here present the results of practical experiments to verify this effect in the transmission electron microscope. We find that with illumination settings typically used in the electron microscopy of biological macromolecules, systematic variations in magnification of ~ 0.5% per μm defocus can easily occur. This work highlights the need for a magnification-invariant imaging mode to eliminate or to compensate for this effect.

  15. Chirped Auger electron emission due to field-assisted post-collision interaction

    Directory of Open Access Journals (Sweden)

    Bonitz M.

    2013-03-01

    Full Text Available We have investigated the Auger decay in the temporal domain by applying a terahertz streaking light field. Xenon and krypton atoms were studied by implementing the free-electron laser in Hamburg (FLASH as well as a source of high-order harmonic radiation combined with terahertz pulses from an optical rectification source. The observed linewidth asymmetries in the streaked spectra suggest a chirped Auger electron emission which is understood in terms of field-assisted post-collision interaction. The experimentally obtained results agree well with model calculations.

  16. Doppler broadening of in-flight positron annihilation radiation due to electron momentum.

    Science.gov (United States)

    Hunt, A W; Cassidy, D B; Sterne, P A; Cowan, T E; Howell, R H; Lynn, K G; Golevchenko, J A

    2001-06-11

    We report the first observation of electron momentum contributions to the Doppler broadening of radiation produced by in-flight two-photon annihilation in solids. In these experiments an approximately 2.5 MeV positron beam impinged on thin polyethylene, aluminum, and gold targets. Since energetic positrons easily penetrate the nuclear Coulomb potential and do not cause a strong charge polarization, the experimental annihilation line shapes agree well with calculations based on a simple independent-particle model. Moreover, annihilations with the deepest core electrons are greatly enhanced.

  17. Further observations of a decreasing atmospheric CO2 uptake capacity in the Canada Basin (Arctic Ocean) due to sea ice loss

    Science.gov (United States)

    Else, Brent G. T.; Galley, R. J.; Lansard, B.; Barber, D. G.; Brown, K.; Miller, L. A.; Mucci, A.; Papakyriakou, T. N.; Tremblay, J.-É.; Rysgaard, S.

    2013-03-01

    data collected in 2009, we evaluated the potential for the southeastern Canada Basin (Arctic Ocean) to act as an atmospheric CO2 sink under the summertime ice-free conditions expected in the near future. Beneath a heavily decayed ice cover, we found surprisingly high pCO2sw (~290-320 µatm), considering that surface water temperatures were low and the influence of ice melt was strong. A simple model simulating melt of the remaining ice and exposure of the surface water for 100 days revealed a weak capacity for atmospheric CO2 uptake (mean flux: -2.4 mmol m-2 d-1), due largely to warming of the shallow mixed layer. Our results confirm a previous finding that the Canada Basin is not a significant sink of atmospheric CO2 under summertime ice-free conditions and that increased ventilation of the surface mixed layer due to sea ice loss is weakening the sink even further.

  18. Front-end electronics and data acquisition system for imaging atmospheric Cherenkov telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.T., E-mail: chenytao@ynu.edu.cn [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Yunnan University, 650091 Kunming (China); La Taille, C. de [OMEGA (UMS 3605) - IN2P3/CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Suomijärvi, T. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Cao, Z. [Institute of High Energy Physics, 100049 Beijing (China); Deligny, O. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Dulucq, F. [OMEGA (UMS 3605) - IN2P3/CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Ge, M.M. [Yunnan University, 650091 Kunming (China); Lhenry-Yvon, I. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Martin-Chassard, G. [OMEGA (UMS 3605) - IN2P3/CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Nguyen Trung, T.; Wanlin, E. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Xiao, G.; Yin, L.Q. [Institute of High Energy Physics, 100049 Beijing (China); Yun Ky, B. [Institut de Physique Nucléaire, IN2P3-CNRS, Université Paris-Sud, 91406 Orsay Cedex (France); Zhang, L. [Yunnan University, 650091 Kunming (China); Zhang, H.Y. [Tsinghua University, 100084 Beijing (China); Zhang, S.S.; Zhu, Z. [Institute of High Energy Physics, 100049 Beijing (China)

    2015-09-21

    In this paper, a front-end electronics based on an application-specific integrated circuit (ASIC) is presented for the future imaging atmospheric Cherenkov telescopes (IACTs). To achieve this purpose, a 16-channel ASIC chip, PARISROC 2 (Photomultiplier ARray Integrated in SiGe ReadOut Chip) is used in the analog signal processing and digitization. The digitized results are sent to the server by a user-defined User Datagram Protocol/Internet Protocol (UDP/IP) hardcore engine through Ethernet that is managed by a FPGA. A prototype electronics fulfilling the requirements of the Wide Field of View Cherenkov Telescope Array (WFCTA) of the Large High Altitude Air Shower Observatory (LHAASO) project has been designed, fabricated and tested to prove the concept of the design. A detailed description of the development with the results of the test measurements are presented. By using a new input structure and a new configuration of the ASIC, the dynamic range of the circuit is extended. A highly precise-time calibrating algorithm is also proposed, verified and optimized for the mass production. The test results suggest that the proposed electronics design fulfills the general specification of the future IACTs.

  19. [Investigation on the electron density of a micro-plasma jet operated at atmospheric pressure].

    Science.gov (United States)

    Li, Xue-chen; Zhao, Na; Liu, Wei-yuan; Liu, Zhi-qiang

    2010-07-01

    In the present paper, a micro-hollow cathode discharge setup was used to generate micro-plasma jet in flowing mixture of Ar and N2 at atmospheric pressure. The characteristics of the micro-plasma jet were investigated by means of optical method and electrical one. It has been found that breakdown occurs in the gas between the two electrodes when the input power of electric source is increased to a certain value. Plasma appears along the gas flow direction when the mixed gas flows from the aperture of the micro-hollow cathode, and the length of plasma reaches 4 mm. The discharge current is quasi-continuous, and the duration of discharge pulse is about 0.1 micros. Electron density was studied by using Einstein equation and Stark broadening of spectral lines from the emission spectrum respectively. It was found that the results of electron density calculated by the two methods are consistent with the order of 10(15) x cm(-3). It was also found that the electron density is almost independent of power. A qualitative explanation to the phenomenon is given based on the gas discharge theory.

  20. Electron residual energy due to stochastic heating in field-ionized plasma

    CERN Document Server

    Khalilzadeh, Elnaz; Jahanpanah, Jafar; Chakhmachi, Amir; Yazdani, Elnaz

    2015-01-01

    The electron residual energy originated from the stochastic heating in under-dense field-ionized plasma is here investigated. The optical response of plasma is initially modeled by using the concept of two counter-propagating electromagnetic waves. The solution of motion equation of a single electron indicates that by including the ionization, the electron with higher residual energy compared to the case without ionization could be obtained. In agreement with chaotic nature of the motion, it is found that the electron residual energy will significantly be changed by applying a minor change to the initial conditions. Extensive kinetic 1D-3V particle-in-cell (PIC) simulations have been performed in order to resolve full plasma reactions. In this way, two different regimes of plasma behavior are observed by varying the pulse length. The results indicate that the amplitude of scattered fields in sufficient long pulse length is high enough to act as a second counter-propagating wave for triggering the stochastic e...

  1. Shifts and Dips in Inelastic Electron Tunneling Spectra Due to the Tunnel Junction Environment.

    Science.gov (United States)

    1981-05-27

    biochemistry,7𔄂 9 10 1water polution , electron beam irradiation, UV irradiation 12and lubrication 2 . Particularly promising applications have...partially oxidized the strip in air at 200 0C to form the alumina insulating barrier. Prior to the catalyst metal evaporation we cleaned the slide in

  2. Ultrarelativistic electron butterfly distributions created by parallel acceleration due to magnetosonic waves

    Science.gov (United States)

    Li, Jinxing; Bortnik, Jacob; Thorne, Richard M.; Li, Wen; Ma, Qianli; Baker, Daniel N.; Reeves, Geoffrey D.; Fennell, Joseph F.; Spence, Harlan E.; Kletzing, Craig A.; Kurth, William S.; Hospodarsky, George B.; Angelopoulos, Vassilis; Blake, J. Bernard.

    2016-04-01

    The Van Allen Probe observations during the recovery phase of a large storm that occurred on 17 March 2015 showed that the ultrarelativistic electrons at the inner boundary of the outer radiation belt (L* = 2.6-3.7) exhibited butterfly pitch angle distributions, while the inner belt and the slot region also showed evidence of sub-MeV electron butterfly distributions. Strong magnetosonic waves were observed in the same regions and at the same time periods as these butterfly distributions. Moreover, when these magnetosonic waves extended to higher altitudes (L* = 4.1), the butterfly distributions also extended to the same region. Combining test particle calculations and Fokker-Planck diffusion simulations, we successfully reproduced the formation of the ultrarelativistic electron butterfly distributions, which primarily result from parallel acceleration caused by Landau resonance with magnetosonic waves. The coexistence of ultrarelativistic electron butterfly distributions with magnetosonic waves was also observed in the 24 June 2015 storm, providing further support that the magnetosonic waves play a key role in forming butterfly distributions.

  3. Continuous and immediate method for the detection of SF/sub 6/ and other tracer gases by electron capture in atmospheric diffusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Thomsen, E.L. (Aerosol Lab., Risoe, Denmark); Lovelock, J.E.

    1976-01-01

    In many atmospheric diffusion experiments using tracer gases continuous tracer recording is of decisive importance. The main obstacle to continuous electron capture detection of tracer gases in the atmosphere is presented by the oxygen, which is an electron capturer. A method for removing this difficulty is described. Its practical use in an airborne atmospheric plume diffusion experiment is demonstrated.

  4. The potential for regional-scale bias in top-down CO2 flux estimates due to atmospheric transport errors

    Directory of Open Access Journals (Sweden)

    S. M. Miller

    2014-09-01

    Full Text Available Estimates of CO2 fluxes that are based on atmospheric data rely upon a meteorological model to simulate atmospheric CO2 transport. These models provide a quantitative link between surface fluxes of CO2 and atmospheric measurements taken downwind. Therefore, any errors in the meteorological model can propagate into atmospheric CO2 transport and ultimately bias the estimated CO2 fluxes. These errors, however, have traditionally been difficult to characterize. To examine the effects of CO2 transport errors on estimated CO2 fluxes, we use a global meteorological model-data assimilation system known as "CAM–LETKF" to quantify two aspects of the transport errors: error variances (standard deviations and temporal error correlations. Furthermore, we develop two case studies. In the first case study, we examine the extent to which CO2 transport uncertainties can bias CO2 flux estimates. In particular, we use a common flux estimate known as CarbonTracker to discover the minimum hypothetical bias that can be detected above the CO2 transport uncertainties. In the second case study, we then investigate which meteorological conditions may contribute to month-long biases in modeled atmospheric transport. We estimate 6 hourly CO2 transport uncertainties in the model surface layer that range from 0.15 to 9.6 ppm (standard deviation, depending on location, and we estimate an average error decorrelation time of ∼2.3 days at existing CO2 observation sites. As a consequence of these uncertainties, we find that CarbonTracker CO2 fluxes would need to be biased by at least 29%, on average, before that bias were detectable at existing non-marine atmospheric CO2 observation sites. Furthermore, we find that persistent, bias-type errors in atmospheric transport are associated with consistent low net radiation, low energy boundary layer conditions. The meteorological model is not necessarily more uncertain in these conditions. Rather, the extent to which meteorological

  5. The potential for regional-scale bias in top-down CO2 flux estimates due to atmospheric transport errors

    Science.gov (United States)

    Miller, S. M.; Fung, I.; Liu, J.; Hayek, M. N.; Andrews, A. E.

    2014-09-01

    Estimates of CO2 fluxes that are based on atmospheric data rely upon a meteorological model to simulate atmospheric CO2 transport. These models provide a quantitative link between surface fluxes of CO2 and atmospheric measurements taken downwind. Therefore, any errors in the meteorological model can propagate into atmospheric CO2 transport and ultimately bias the estimated CO2 fluxes. These errors, however, have traditionally been difficult to characterize. To examine the effects of CO2 transport errors on estimated CO2 fluxes, we use a global meteorological model-data assimilation system known as "CAM-LETKF" to quantify two aspects of the transport errors: error variances (standard deviations) and temporal error correlations. Furthermore, we develop two case studies. In the first case study, we examine the extent to which CO2 transport uncertainties can bias CO2 flux estimates. In particular, we use a common flux estimate known as CarbonTracker to discover the minimum hypothetical bias that can be detected above the CO2 transport uncertainties. In the second case study, we then investigate which meteorological conditions may contribute to month-long biases in modeled atmospheric transport. We estimate 6 hourly CO2 transport uncertainties in the model surface layer that range from 0.15 to 9.6 ppm (standard deviation), depending on location, and we estimate an average error decorrelation time of ∼2.3 days at existing CO2 observation sites. As a consequence of these uncertainties, we find that CarbonTracker CO2 fluxes would need to be biased by at least 29%, on average, before that bias were detectable at existing non-marine atmospheric CO2 observation sites. Furthermore, we find that persistent, bias-type errors in atmospheric transport are associated with consistent low net radiation, low energy boundary layer conditions. The meteorological model is not necessarily more uncertain in these conditions. Rather, the extent to which meteorological uncertainties

  6. Universal power-law decay of electron-electron interactions due to nonlinear screening in a Josephson junction array

    Science.gov (United States)

    Otten, Daniel; Rubbert, Sebastian; Ulrich, Jascha; Hassler, Fabian

    2016-09-01

    Josephson junctions are the most prominent nondissipative and at the same time nonlinear elements in superconducting circuits allowing Cooper pairs to tunnel coherently between two superconductors separated by a tunneling barrier. Due to this, physical systems involving Josephson junctions show highly complex behavior and interesting novel phenomena. Here, we consider an infinite one-dimensional chain of superconducting islands where neighboring islands are coupled by capacitances. We study the effect of Josephson junctions shunting each island to a common ground superconductor. We treat the system in the regime where the Josephson energy exceeds the capacitive coupling between the islands. For the case of two offset charges on two distinct islands, we calculate the interaction energy of these charges mediated by quantum phase slips due to the Josephson nonlinearities. We treat the phase slips in an instanton approximation and map the problem onto a classical partition function of interacting particles. Using the Mayer cluster expansion, we find that the interaction potential of the offset charges decays with a universal inverse-square power-law behavior.

  7. Forces due to changes of electronic density: A complementary view of the Jahn-Teller effect

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Lastra, J.M. [Departamento de Fisica Moderna, Universidad de Cantabria, 39005 Santander (Spain); Barriuso, M.T. [Departamento de Fisica Moderna, Universidad de Cantabria, 39005 Santander (Spain); Aramburu, J.A. [Departamento de Ciencias de la Tierra y Fisica de la Materia Condensada, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain)], E-mail: aramburj@unican.es; Moreno, M. [Departamento de Ciencias de la Tierra y Fisica de la Materia Condensada, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain)

    2005-10-10

    The E x e Jahn-Teller (JT) effect in an octahedral complex is explored in this work looking directly at forces on ligand ions. It is shown that distortions at adiabatic minima are driven by a force associated with the difference between the real electronic density and that coming from a closed shell ion keeping the same number of electrons. Through this more direct approach main characteristics of tetragonal distortions are shown to be well reproduced in a simple case. As a salient feature the existence of an infinity of equivalent distortions when anharmonicity of vibrations is ignored is also found in the present approach. The way of applying these ideas to other JT systems as well as to excited states of transition-metal complexes is also briefly discussed.

  8. Enhanced radial transport and energization of radiation belt electrons due to drift orbit bifurcations.

    Science.gov (United States)

    Ukhorskiy, A Y; Sitnov, M I; Millan, R M; Kress, B T; Smith, D C

    2014-01-01

    [1]Relativistic electron intensities in Earth's outer radiation belt can vary by multiple orders of magnitude on the time scales ranging from minutes to days. One fundamental process contributing to dynamic variability of radiation belt intensities is the radial transport of relativistic electrons across their drift shells. In this paper we analyze the properties of three-dimensional radial transport in a global magnetic field model driven by variations in the solar wind dynamic pressure. We use a test particle approach which captures anomalous effects such as drift orbit bifurcations. We show that the bifurcations lead to an order of magnitude increase in radial transport rates and enhance the energization at large equatorial pitch angles. Even at quiet time fluctuations in dynamic pressure, radial transport at large pitch angles exhibits strong deviations from the diffusion approximation. The radial transport rates are much lower at small pitch angle values which results in a better agreement with the diffusion approximation.

  9. Energetic Electron Pitch Angle Diffusion due to Whistler Wave during Terrestrial Storms

    Institute of Scientific and Technical Information of China (English)

    XIAO Fu-Liang; HE Hui-Yong

    2006-01-01

    A concise and elegant expression of cyclotron harmonic resonant quasi-pure pitch-angle diffusion is constructed for the parallel whistler mode waves, and the quasi-linear diffusion coefficient is prescribed in terms of the whistler mode wave spectral intensity. Numerical computations are performed for the specific case of energetic electrons interacting with a band of frequency of whistler mode turbulence at L ≈ 3. It is found that the quasi-pure pitch-angle diffusion driven by the whistler mode scatters energetic electrons from the larger pitch-angles into the loss cone, and causes pitch-angle distribution to evolve from the pancake-shaped before the terrestrial storms to the flat-top during the main phase. This probably accounts for the quasi-isotropic pitch-angle distribution observed by the combined release and radiation effects satellite spacecraft at L ≈ 3.

  10. Local Classical and Quantum Criticality due to Electron-Vibration Interaction

    OpenAIRE

    2009-01-01

    We study the local classical and quantum critical properties of electron-vibration interaction, represented by the Yu-Anderson model. It exhibits an instability, similar to the Wentzel-Bardeen singularity, whose nature resembles to weakly first order quantum phase transitions at low temperatures, and crosses over to Gaussian behaviour with increasing temperature. We determine the dominant energy scale separating the quantum from classical criticality, study the effect of dissipation and analy...

  11. The influence of Middle Range Energy Electrons on atmospheric chemistry and regional climate

    Science.gov (United States)

    Arsenovic, P.; Rozanov, E.; Stenke, A.; Funke, B.; Wissing, J. M.; Mursula, K.; Tummon, F.; Peter, T.

    2016-11-01

    We investigate the influence of Middle Range Energy Electrons (MEE; typically 30-300 keV) precipitation on the atmosphere using the SOCOL3-MPIOM chemistry-climate model with coupled ocean. Model simulations cover the 2002-2010 period for which ionization rates from the AIMOS dataset and atmospheric composition observations from MIPAS are available. Results show that during geomagnetically active periods MEE significantly increase the amount of NOy and HOx in the polar winter mesosphere, in addition to other particles and sources, resulting in local ozone decreases of up to 35%. These changes are followed by an intensification of the polar night jet, as well as mesospheric warming and stratospheric cooling. The contribution of MEE also substantially enhances the difference in the ozone anomalies between geomagnetically active and quiet periods. Comparison with MIPAS NOy observations indicates that the additional source of NOy from MEE improves the model results, however substantial underestimation above 50 km remains and requires better treatment of the NOy source from the thermosphere. A surface air temperature response is detected in several regions, with the most pronounced warming occurring in the Antarctic during austral winter. Surface warming of up to 2 K is also seen over continental Asia during boreal winter.

  12. Lagrangian for Frenkel electron and position's non-commutativity due to spin

    Energy Technology Data Exchange (ETDEWEB)

    Deriglazov, Alexei A. [Universidade Federal de Juiz de Fora, Depto. de Matematica, ICE, Juiz de Fora, MG (Brazil); Tomsk Polytechnic University, Laboratory of Mathematical Physics, Tomsk (Russian Federation); Pupasov-Maksimov, Andrey M. [Universidade Federal de Juiz de Fora, Depto. de Matematica, ICE, Juiz de Fora, MG (Brazil)

    2014-10-15

    We construct a relativistic spinning-particle Lagrangian where spin is considered as a composite quantity constructed on the base of a non-Grassmann vector-like variable. The variational problem guarantees both a fixed value of the spin and the Frenkel condition on the spin-tensor. The Frenkel condition inevitably leads to relativistic corrections of the Poisson algebra of the position variables: their classical brackets became noncommutative. We construct the relativistic quantum mechanics in the canonical formalism (in the physical-time parametrization) and in the covariant formalism (in an arbitrary parametrization). We show how state vectors and operators of the covariant formulation can be used to compute the mean values of physical operators in the canonical formalism, thus proving its relativistic covariance. We establish relations between the Frenkel electron and positive-energy sector of the Dirac equation. Various candidates for the position and spin operators of an electron acquire clear meaning and interpretation in the Lagrangian model of the Frenkel electron. Our results argue in favor of Pryce's (d)-type operators as the spin and position operators of Dirac theory. This implies that the effects of non-commutativity could be expected already at the Compton wavelength. We also present the manifestly covariant form of the spin and position operators of the Dirac equation. (orig.)

  13. Degradation of near infrared and shortwave infrared imager performance due to atmospheric scattering of diffuse night illumination.

    Science.gov (United States)

    Vollmerhausen, Richard

    2013-07-20

    On moonless nights, airglow is the primary source of natural ground illumination in the near infrared and shortwave infrared spectral bands. Therefore, night vision imagers operating in these spectral bands view targets that are diffusely illuminated. Aerosol scattering of diffuse airglow illumination causes atmospheric path radiance and that radiance causes increased imager noise. These phenomena and their quantification are described in this paper.

  14. Low atmospheric CO2 levels during the Little Ice Age due to cooling-induced terrestrial uptake

    Science.gov (United States)

    Rubino, M.; Etheridge, D. M.; Trudinger, C. M.; Allison, C. E.; Rayner, P. J.; Enting, I.; Mulvaney, R.; Steele, L. P.; Langenfelds, R. L.; Sturges, W. T.; Curran, M. A. J.; Smith, A. M.

    2016-09-01

    Low atmospheric carbon dioxide (CO2) concentration during the Little Ice Age has been used to derive the global carbon cycle sensitivity to temperature. Recent evidence confirms earlier indications that the low CO2 was caused by increased terrestrial carbon storage. It remains unknown whether the terrestrial biosphere responded to temperature variations, or there was vegetation re-growth on abandoned farmland. Here we present a global numerical simulation of atmospheric carbonyl sulfide concentrations in the pre-industrial period. Carbonyl sulfide concentration is linked to changes in gross primary production and shows a positive anomaly during the Little Ice Age. We show that a decrease in gross primary production and a larger decrease in ecosystem respiration is the most likely explanation for the decrease in atmospheric CO2 and increase in atmospheric carbonyl sulfide concentrations. Therefore, temperature change, not vegetation re-growth, was the main cause of the increased terrestrial carbon storage. We address the inconsistency between ice-core CO2 records from different sites measuring CO2 and δ13CO2 in ice from Dronning Maud Land (Antarctica). Our interpretation allows us to derive the temperature sensitivity of pre-industrial CO2 fluxes for the terrestrial biosphere (γL = -10 to -90 Pg C K-1), implying a positive climate feedback and providing a benchmark to reduce model uncertainties.

  15. Energy Loss of Solar p Modes due to the Excitation of Magnetic Sausage Tube Waves: Importance of Coupling the Upper Atmosphere

    Science.gov (United States)

    Gascoyne, A.; Jain, R.; Hindman, B. W.

    2014-07-01

    We consider damping and absorption of solar p modes due to their energy loss to magnetic tube waves that can freely carry energy out of the acoustic cavity. The coupling of p modes and sausage tube waves is studied in a model atmosphere composed of a polytropic interior above which lies an isothermal upper atmosphere. The sausage tube waves, excited by p modes, propagate along a magnetic fibril which is assumed to be a vertically aligned, stratified, thin magnetic flux tube. The deficit of p-mode energy is quantified through the damping rate, Γ, and absorption coefficient, α. The variation of Γ and α as a function of frequency and the tube's plasma properties is studied in detail. Previous similar studies have considered only a subphotospheric layer, modeled as a polytrope that has been truncated at the photosphere. Such studies have found that the resulting energy loss by the p modes is very sensitive to the upper boundary condition, which, due to the lack of an upper atmosphere, have been imposed in a somewhat ad hoc manner. The model presented here avoids such problems by using an isothermal layer to model the overlying atmosphere (chromosphere, and, consequently, allows us to analyze the propagation of p-mode-driven sausage waves above the photosphere. In this paper, we restrict our attention to frequencies below the acoustic cut off frequency. We demonstrate the importance of coupling all waves (acoustic, magnetic) in the subsurface solar atmosphere with the overlying atmosphere in order to accurately model the interaction of solar f and p modes with sausage tube waves. In calculating the absorption and damping of p modes, we find that for low frequencies, below ≈3.5 mHz, the isothermal atmosphere, for the two-region model, behaves like a stress-free boundary condition applied at the interface (z = -z 0).

  16. Energy loss of solar p modes due to the excitation of magnetic sausage tube waves: Importance of coupling the upper atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Gascoyne, A.; Jain, R. [Applied Mathematics Department, University of Sheffield, Sheffield S3 7RH (United Kingdom); Hindman, B. W., E-mail: a.d.gascoyne@sheffield.ac.uk, E-mail: r.jain@sheffield.ac.uk [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado at Boulder, Boulder, CO 80309-0440 (United States)

    2014-07-10

    We consider damping and absorption of solar p modes due to their energy loss to magnetic tube waves that can freely carry energy out of the acoustic cavity. The coupling of p modes and sausage tube waves is studied in a model atmosphere composed of a polytropic interior above which lies an isothermal upper atmosphere. The sausage tube waves, excited by p modes, propagate along a magnetic fibril which is assumed to be a vertically aligned, stratified, thin magnetic flux tube. The deficit of p-mode energy is quantified through the damping rate, Γ, and absorption coefficient, α. The variation of Γ and α as a function of frequency and the tube's plasma properties is studied in detail. Previous similar studies have considered only a subphotospheric layer, modeled as a polytrope that has been truncated at the photosphere. Such studies have found that the resulting energy loss by the p modes is very sensitive to the upper boundary condition, which, due to the lack of an upper atmosphere, have been imposed in a somewhat ad hoc manner. The model presented here avoids such problems by using an isothermal layer to model the overlying atmosphere (chromosphere, and, consequently, allows us to analyze the propagation of p-mode-driven sausage waves above the photosphere. In this paper, we restrict our attention to frequencies below the acoustic cut off frequency. We demonstrate the importance of coupling all waves (acoustic, magnetic) in the subsurface solar atmosphere with the overlying atmosphere in order to accurately model the interaction of solar f and p modes with sausage tube waves. In calculating the absorption and damping of p modes, we find that for low frequencies, below ≈3.5 mHz, the isothermal atmosphere, for the two-region model, behaves like a stress-free boundary condition applied at the interface (z = –z{sub 0}).

  17. Resonance broadening due to particle scattering and mode-coupling in the quasi-linear relaxation of electron beams

    CERN Document Server

    Bian, Nicolas H; Ratcliffe, Heather

    2015-01-01

    Of particular interest for radio and hard X-ray diagnostics of accelerated electrons during solar flares is the understanding of the basic non-linear mechanisms regulating the relaxation of electron beams propagating in turbulent plasmas. In this work, it is shown that in addition to scattering of beam electrons, scattering of the beam-generated Langmuir waves via for instance mode-coupling, can also result in broadening of the wave-particle resonance. We obtain a resonance-broadened version of weak-turbulence theory with mode-coupling to ion-sound modes. Resonance broadening is presented here as a unified framework which can quantitatively account for the reduction and possible suppression of the beam instability due to background scattering of the beam electrons themselves or due to scattering of the beam-generated Langmuir waves in fluctuating plasmas. Resonance broadening being essentially equivalent to smoothing of the electron phase-space distribution, it is used to construct an intuitive physical pictu...

  18. Scattering rates due to electron-phonon interaction in CdS1-xSex quantum dots

    Science.gov (United States)

    Alcalde, Augusto M.; Weber, Gerald

    2000-11-01

    We calculate electron-LO-confined and surface phonon scattering rates in CdS1-xSex spherical quantum dots. The phonon modes are described in the frame of the two-mode dielectric continuum model, and the standard k.p formalism is used for treating the electronic band structure. We include the effects of inhomogeneous broadening due to statistical dot size distribution, which can create a wide channel of efficient relaxation. We demonstrate that changes in the concentration can generate variations of more than one order of magnitude in the relaxation rates.

  19. Bond selectivity in electron-induced reaction due to directed recoil on an anisotropic substrate

    Science.gov (United States)

    Anggara, Kelvin; Huang, Kai; Leung, Lydie; Chatterjee, Avisek; Cheng, Fang; Polanyi, John C.

    2016-12-01

    Bond-selective reaction is central to heterogeneous catalysis. In heterogeneous catalysis, selectivity is found to depend on the chemical nature and morphology of the substrate. Here, however, we show a high degree of bond selectivity dependent only on adsorbate bond alignment. The system studied is the electron-induced reaction of meta-diiodobenzene physisorbed on Cu(110). Of the adsorbate's C-I bonds, C-I aligned `Along' the copper row dissociates in 99.3% of the cases giving surface reaction, whereas C-I bond aligned `Across' the rows dissociates in only 0.7% of the cases. A two-electronic-state molecular dynamics model attributes reaction to an initial transition to a repulsive state of an Along C-I, followed by directed recoil of C towards a Cu atom of the same row, forming C-Cu. A similar impulse on an Across C-I gives directed C that, moving across rows, does not encounter a Cu atom and hence exhibits markedly less reaction.

  20. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    CERN Document Server

    Talman, Richard; Stulle, Frank

    2009-01-01

    Evolution of short intense electron bunches passing through bunch-compressing beam lines is studied using the UAL (Unified Accelerator Libraries) string space charge formulation [R. Talman, Phys. Rev. ST Accel. Beams 7, 100701 (2004); N. Malitsky and R. Talman, in Proceedings of the 9th European Particle Accelerator Conference, Lucerne, 2004 (EPS-AG, Lucerne, 2004); R. Talman, Accelerator X-Ray Sources (Wiley-VCH, Weinheim, 2006), Chap. 13]. Three major configurations are studied, with the first most important and studied in greatest detail (because actual experimental results are available and the same results have been simulated with other codes): (i) Experimental bunch compression results were obtained at CTF-II, the CERN test facility for the “Compact Linear Collider” using electrons of about 40 MeV. Previous simulations of these results have been performed (using trafic4* [A. Kabel et al., Nucl. Instrum. Methods Phys. Res., Sect. A 455, 185 (2000)] and elegant [M. Borland, Argonne National Laboratory...

  1. Atmospheric measurements of carbonyl sulfide, dimethyl sulfide, and carbon disulfide using the electron capture sulfur detector

    Science.gov (United States)

    Johnson, James E.; Bates, Timothy S.

    1993-01-01

    Measurements of atmospheric dimethyl sulfide (DMS), carbonyl sulfide (COS), and carbon disulfide (CS2) were conducted over the Atlantic Ocean on board the NASA Electra aircraft during the Chemical Instrumentation Test and Evaluation (CITE 3) project using the electron capture sulfur detector (ECD-S). The system employed cryogenic preconcentration of air samples, gas chromatographic separation, catalytic fluorination, and electron capture detection. Samples collected for DMS analysis were scrubbed of oxidants with NaOH impregnated glass fiber filters to preconcentration. The detection limits (DL) of the system for COS, DMS, and CS2 were 5, 5, and 2 ppt, respectively. COS concentrations ranged from 404 to 603 ppt with a mean of 489 ppt for measurements over the North Atlantic Ocean (31 deg N to 41 deg N), and from 395 to 437 ppt with a mean of 419 ppt for measurements over the Tropical Atlantic Ocean (11 deg S to 2 deg N). DMS concentrations in the lower marine boundary layer, below 600-m altitude, ranged from below DL to 150 ppt from flights over the North Atlantic, and from 9 to 104 ppt over the Tropical Atlantic. CS2 concentrations ranged from below DL to 29 ppt over the North Atlantic. Almost all CS2 measurements over the Tropical Atlantic were below DL.

  2. The influence of electron collisions on non-LTE Li line formation in stellar atmospheres

    CERN Document Server

    Osorio, Y; Lind, K; Asplund, M

    2011-01-01

    The influence of uncertainties in the rate coefficient data for electron-impact excitation and ionization on non-LTE Li line formation in cool stellar atmospheres is investigated. We examine the collision data used in previous non-LTE calculations and compare with recent calculations using convergent close-coupling (CCC) techniques, as well our own calculations using the R-matrix with pseudostates (RMPS) method. We find excellent agreement between rate coefficients from the CCC and RMPS calculations, and reasonable agreement between these data and the semi-empirical data used in non-LTE calculations up till now. The results of non-LTE calculations using the old and new data sets are compared and only small differences are found; of order 0.01 dex (~ 2%) or less in the abundance corrections. We therefore conclude that electron collision data are not a significant source of uncertainty in non-LTE Li line formation calculations. Indeed, together with the collision data for the charge exchange process Li(3s) + H ...

  3. Imaging of bacterial multicellular behaviour in biofilms in liquid by atmospheric scanning electron microscopy

    Science.gov (United States)

    Sugimoto, Shinya; Okuda, Ken-ichi; Miyakawa, Reina; Sato, Mari; Arita-Morioka, Ken-ichi; Chiba, Akio; Yamanaka, Kunitoshi; Ogura, Teru; Mizunoe, Yoshimitsu; Sato, Chikara

    2016-01-01

    Biofilms are complex communities of microbes that attach to biotic or abiotic surfaces causing chronic infectious diseases. Within a biofilm, microbes are embedded in a self-produced soft extracellular matrix (ECM), which protects them from the host immune system and antibiotics. The nanoscale visualisation of delicate biofilms in liquid is challenging. Here, we develop atmospheric scanning electron microscopy (ASEM) to visualise Gram-positive and -negative bacterial biofilms immersed in aqueous solution. Biofilms cultured on electron-transparent film were directly imaged from below using the inverted SEM, allowing the formation of the region near the substrate to be studied at high resolution. We visualised intercellular nanostructures and the exocytosis of membrane vesicles, and linked the latter to the trafficking of cargos, including cytoplasmic proteins and the toxins hemolysin and coagulase. A thick dendritic nanotube network was observed between microbes, suggesting multicellular communication in biofilms. A universal immuno-labelling system was developed for biofilms and tested on various examples, including S. aureus biofilms. In the ECM, fine DNA and protein networks were visualised and the precise distribution of protein complexes was determined (e.g., straight curli, flagella, and excreted cytoplasmic molecular chaperones). Our observations provide structural insights into bacteria-substratum interactions, biofilm development and the internal microbe community. PMID:27180609

  4. Tailoring electron energy distribution functions through energy confinement in dual radio-frequency driven atmospheric pressure plasmas

    Energy Technology Data Exchange (ETDEWEB)

    O' Neill, C.; Waskoenig, J. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Gans, T. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom)

    2012-10-08

    A multi-scale numerical model based on hydrodynamic equations with semi-kinetic treatment of electrons is used to investigate the influence of dual frequency excitation on the effective electron energy distribution function (EEDF) in a radio-frequency driven atmospheric pressure plasma. It is found that variations of power density, voltage ratio, and phase relationship provide separate control over the electron density and the mean electron energy. This is exploited to directly influence both the phase dependent and time averaged effective EEDF. This enables tailoring the EEDF for enhanced control of non-equilibrium plasma chemical kinetics at ambient pressure and temperature.

  5. Solar radiation absorption in the atmosphere due to water and ice clouds: Sensitivity experiments with plane-parallel clouds

    Energy Technology Data Exchange (ETDEWEB)

    Gautier, C. [Univ. of California, Santa Barbara, CA (United States)

    1995-09-01

    One cloud radiation issue that has been troublesome for several decades is the absorption of solar radiation by clouds. Many hypotheses have been proposed to explain the discrepancies between observations and modeling results. A good review of these often-competing hypotheses has been provided by Stephens and Tsay. They characterize the available hypotheses as failing into three categories: (1) those linked to cloud microphysical and consequent optical properties; (2) those linked to the geometry and heterogeneity of clouds; and (3) those linked to atmospheric absorption.Current modeling practice is seriously inconsistent with new observational inferences concerning absorption of solar radiation in the atmosphere. The author and her colleagues contend that an emphasis on R may, therefore, not be the optimal way of addressing the cloud solar absorption issue. 4 refs., 1 fig.

  6. Charging dynamics of a polymer due to electron irradiation: A simultaneous scattering-transport model and preliminary results

    Institute of Scientific and Technical Information of China (English)

    Cao Meng; Wang Fang; Liu Jing; Zhang Hai-Bo

    2012-01-01

    We present a novel numerical model and simulate preliminarily the charging process of a polymer subjected to electron irradiation of several 10 keV.The model includes the simultaneous processes of electron scattering and ambipolar transport and the influence of a self-consistent electric field on the scattering distribution of electrons.The dynamic spatial distribution of charges is obtained and validated by existing experimental data.Our simulations show that excess negative charges are concentrated near the edge of the electron range.However,the formed region of high charge density may extend to the surface and bottom of a kapton sample,due to the effects of the electric field on electron scattering and charge transport,respectively.Charge trapping is then demonstrated to significantly influence the charge motion.The charge distribution can be extended to the bottom as the trap density decreases.Charge accumulation is therefore balanced by the appearance and increase of leakage current.Accordingly,our model and numerical simulation provide a comprehensive insight into the charging dynamics of a polymer irradiated by electrons in the complex space environment.

  7. Secretory glands and microvascular systems imaged in aqueous solution by atmospheric scanning electron microscopy (ASEM).

    Science.gov (United States)

    Yamazawa, Toshiko; Nakamura, Naotoshi; Sato, Mari; Sato, Chikara

    2016-12-01

    Exocrine glands, e.g., salivary and pancreatic glands, play an important role in digestive enzyme secretion, while endocrine glands, e.g., pancreatic islets, secrete hormones that regulate blood glucose levels. The dysfunction of these secretory organs immediately leads to various diseases, such as diabetes or Sjögren's syndrome, by poorly understood mechanisms. Gland-related diseases have been studied by optical microscopy (OM), and at higher resolution by transmission electron microscopy (TEM) of Epon embedded samples, which necessitates hydrophobic sample pretreatment. Here, we report the direct observation of tissue in aqueous solution by atmospheric scanning electron microscopy (ASEM). Salivary glands, lacrimal glands, and pancreas were fixed, sectioned into slabs, stained with phosphotungstic acid (PTA), and inspected in radical scavenger d-glucose solution from below by an inverted scanning electron microscopy (SEM), guided by optical microscopy from above to target the tissue substructures. A 2- to 3-µm specimen thickness was visualized by the SEM. In secretory cells, cytoplasmic vesicles and other organelles were clearly imaged at high resolution, and the former could be classified according to the degree of PTA staining. In islets of Langerhans, the microvascular system used as an outlet by the secretory cells was also clearly observed. Microvascular system is also critically involved in the onset of diabetic complications and was clearly visible in subcutaneous tissue imaged by ASEM. The results suggest the use of in-solution ASEM for histology and to study vesicle secretion systems. Further, the high-throughput of ASEM makes it a potential tool for the diagnosis of exocrine and endocrine-related diseases.

  8. Electromagnetic field generation in the downstream of electrostatic shocks due to electron trapping

    CERN Document Server

    Stockem, A; Fonseca, R A; Silva, L O

    2014-01-01

    A new magnetic field generation mechanism in electrostatic shocks is found, which can produce fields with magnetic energy density as high as 0.01 of the kinetic energy density of the flows on time scales $ \\tilde \\, 10^4 \\, {\\omega}_{pe}^{-1}$. Electron trapping during the shock formation process creates a strong temperature anisotropy in the distribution function, giving rise to the pure Weibel instability. The generated magnetic field is well-confined to the downstream region of the electrostatic shock. The shock formation process is not modified and the features of the shock front responsible for ion acceleration, which are currently probed in laser-plasma laboratory experiments, are maintained. However, such a strong magnetic field determines the particle trajectories downstream and has the potential to modify the signatures of the collisionless shock.

  9. Corkscrew Motion of an Electron Beam due to Coherent Variations in Accelerating Potentials

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, Carl August [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-13

    Corkscrew motion results from the interaction of fluctuations of beam electron energy with accidental magnetic dipoles caused by misalignment of the beam transport solenoids. Corkscrew is a serious concern for high-current linear induction accelerators (LIA). A simple scaling law for corkscrew amplitude derived from a theory based on a constant-energy beam coasting through a uniform magnetic field has often been used to assess LIA vulnerability to this effect. We use a beam dynamics code to verify that this scaling also holds for an accelerated beam in a non-uniform magnetic field, as in a real accelerator. Results of simulations with this code are strikingly similar to measurements on one of the LIAs at Los Alamos National Laboratory.

  10. Electronic tracking of human resource skills and knowledge, just in time training, manageable due diligence

    Energy Technology Data Exchange (ETDEWEB)

    Kolodziej, M.A. [Quick Test International Inc., (Canada). Canadian Technology Human Resource Board; Baker, O. [KeySpan Energy Canada, Calgary, AB (Canada)

    2001-06-01

    KeySpan Energy Canada is in the process of obtaining recognition of various occupational profiles including pipeline operators, inspectors, and field and plant operators from various certifying organizations. The process of allowing individuals to obtain certification is recognized by Canadian Technology Human Resources Board as a step towards national standards for technologists and technicians. Proven competency is a must for workers in todays oil industry in response to increasingly stringent government safety regulations, environmental concerns and high public scrutiny. Quick Test international Inc. has developed a management tool in collaboration with end users at KeySpan Energy Canada. It is an electronic, Internet based competency tool for tracking personal competencies and maintaining continued competency. Response to the tool has been favourable. 2 refs., 4 figs.

  11. Electronic confinement in graphene quantum rings due to substrate-induced mass radial kink

    Science.gov (United States)

    Xavier, L. J. P.; da Costa, D. R.; Chaves, A.; Pereira, J. M., Jr.; Farias, G. A.

    2016-12-01

    We investigate localized states of a quantum ring confinement in monolayer graphene defined by a circular mass-related potential, which can be induced e.g. by interaction with a substrate that breaks the sublattice symmetry, where a circular line defect provides a change in the sign of the induced mass term along the radial direction. Electronic properties are calculated analytically within the Dirac-Weyl approximation in the presence of an external magnetic field. Analytical results are also compared with those obtained by the tight-binding approach. Regardless of its sign, a mass term Δ is expected to open a gap for low-energy electrons in Dirac cones in graphene. Both approaches confirm the existence of confined states with energies inside the gap, even when the width of the kink modelling the mass sign transition is infinitely thin. We observe that such energy levels are inversely proportional to the defect line ring radius and independent on the mass kink height. An external magnetic field is demonstrated to lift the valley degeneracy in this system and easily tune the valley index of the ground state in this system, which can be polarized on either K or {{K}\\prime} valleys of the Brillouin zone, depending on the magnetic field intensity. Geometrical changes in the defect line shape are considered by assuming an elliptic line with different eccentricities. Our results suggest that any defect line that is closed in a loop, with any geometry, would produce the same qualitative results as the circular ones, as a manifestation of the topologically protected nature of the ring-like states investigated here.

  12. Electron density in amplitude modulated microwave atmospheric plasma jet as determined from microwave interferometry and emission spectroscopy

    Science.gov (United States)

    Faltýnek, J.; Hnilica, J.; Kudrle, V.

    2017-01-01

    Time resolved electron density in an atmospheric pressure amplitude modulated microwave plasma jet is determined using the microwave interferometry method, refined by numerical modelling of the propagation of non-planar electromagnetic waves in the vicinity of a small diameter, dense collisional plasma filament. The results are compared to those from the Stark broadening of the {{\\text{H}}β} emission line. Both techniques show, both qualitatively and quantitatively, a similar temporal evolution of electron density during one modulation period.

  13. Record high peaks in PCB concentrations in the Arctic atmosphere due to long-range transport of biomass burning emissions

    Directory of Open Access Journals (Sweden)

    S. Eckhardt

    2007-05-01

    Full Text Available Soils and forests in the boreal region of the northern hemisphere are recognised as having a large capacity for storing air-borne Persistent Organic Pollutants (POPs, such as the polychlorinated biphenyls (PCBs. Following reductions of primary emissions of various legacy POPs, there is an increasing interest and debate about the relative importance of secondary re-emissions on the atmospheric levels of POPs. In spring of 2006, biomass burning emissions from agricultural fires in Eastern Europe were transported to the Zeppelin station on Svalbard, where record-high levels of many air pollutants were recorded (Stohl et al., 2007. Here we report on the extremely high concentrations of PCBs that were also measured during this period. 21 out of 32 PCB congeners were enhanced by more than two standard deviations above the long-term mean concentrations. In July 2004, about 5.8 million hectare of boreal forest burned in North America, emitting a pollution plume which reached the Zeppelin station after a travel time of 3–4 weeks (Stohl et al., 2006. Again, 12 PCB congeners were elevated above the long-term mean by more than two standard deviations, with the less chlorinated congeners being most strongly affected. We propose that these abnormally high concentrations were caused by biomass burning emissions. Based on enhancement ratios with carbon monoxide and known emissions factors for this species, we estimate that 130 and 66 μg PCBs were released per kilogram dry matter burned, respectively. To our knowledge, this is the first study relating atmospheric PCB enhancements with biomass burning. The strong effects on observed concentrations far away from the sources, suggest that biomass burning is an important source of PCBs for the atmosphere.

  14. Resonance frequency shifts due to quantized electronic states in atomically thin NEMS

    Science.gov (United States)

    Chen, Changyao; Deshpande, Vikram; Koshino, Mikito; Lee, Sunwoo; Gondarenko, Alexander; MacDonald, Allan; Kim, Philip; Hone, James

    The classic picture of the force exerted on a parallel plate capacitor assumes infinite density of states (DOS), which implies identical electrochemical and electrostatic potential. However, such assumption can breakdown in low-dimensional devices where the DOS is finite or quantized. Here we consider the mechanical resonance shift of a nanoelectromechanical (NEMS) resonator with small DOS, actuated and detected capacitively at fixed electrochemical potential. We found three leading correction terms to the classical picture: the first term leads to the modulation of static force due to the variation in chemical potential, and the second and third terms are related to the static and dynamic changes in spring constants, caused by quantum capacitance. The theory agrees well with recent experimental findings from graphene resonator in quantum Hall regimes, where the chemical potential and quantum capacitance are tuned by magnetic field, while the gate voltage is kept constant.

  15. Atmospheric scanning electron microscope system with an open sample chamber: Configuration and applications

    Energy Technology Data Exchange (ETDEWEB)

    Nishiyama, Hidetoshi, E-mail: hinishiy@jeol.co.jp [JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo 196-8558 (Japan); Koizumi, Mitsuru, E-mail: koizumi@jeol.co.jp [JEOL Technics Ltd., 2-6-38 Musashino, Akishima, Tokyo 196-0021 (Japan); Ogawa, Koji, E-mail: kogawa@jeol.co.jp [JEOL Technics Ltd., 2-6-38 Musashino, Akishima, Tokyo 196-0021 (Japan); Kitamura, Shinich, E-mail: kitamura@jeol.co.jp [JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo 196-8558 (Japan); Konyuba, Yuji, E-mail: ykonyuub@jeol.co.jp [JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo 196-8558 (Japan); Watanabe, Yoshiyuki, E-mail: watanabeyoshiy@pref.yamagata.jp [Yamagata Research Institute of Technology, 2-2-1, Matsuei, Yamagata 990-2473 (Japan); Ohbayashi, Norihiko, E-mail: n.ohbayashi@m.tohoku.ac.jp [Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Fukuda, Mitsunori, E-mail: nori@m.tohoku.ac.jp [Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Suga, Mitsuo, E-mail: msuga@jeol.co.jp [JEOL Ltd., 3-1-2, Musashino, Akishima, Tokyo 196-8558 (Japan); Sato, Chikara, E-mail: ti-sato@aist.go.jp [Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-4, Umezono, Tsukuba 305-8568 (Japan)

    2014-12-15

    An atmospheric scanning electron microscope (ASEM) with an open sample chamber and optical microscope (OM) is described and recent developments are reported. In this ClairScope system, the base of the open sample dish is sealed to the top of the inverted SEM column, allowing the liquid-immersed sample to be observed by OM from above and by SEM from below. The optical axes of the two microscopes are aligned, ensuring that the same sample areas are imaged to realize quasi-simultaneous correlative microscopy in solution. For example, the cathodoluminescence of ZnO particles was directly demonstrated. The improved system has (i) a fully motorized sample stage, (ii) a column protection system in the case of accidental window breakage, and (iii) an OM/SEM operation system controlled by a graphical user interface. The open sample chamber allows the external administration of reagents during sample observation. We monitored the influence of added NaCl on the random motion of silica particles in liquid. Further, using fluorescence as a transfection marker, the effect of small interfering RNA-mediated knockdown of endogenous Varp on Tyrp1 trafficking in melanocytes was examined. A temperature-regulated titanium ASEM dish allowed the dynamic observation of colloidal silver nanoparticles as they were heated to 240 °C and sintered. - Highlights: • Atmospheric SEM (ASEM) allows observation of samples in liquid or gas. • Open sample chamber allows in situ monitoring of evaporation and sintering processes. • in situ monitoring of processes during reagent administration is also accomplished. • Protection system for film breakage is developed for ASEM. • Usability of ASEM has been improved significantly including GUI control.

  16. Climate sensitivity due to increased CO2: experiments with a coupled atmosphere and ocean general circulation model

    Science.gov (United States)

    Washington, Warren M.; Meehl, Gerald A.

    1989-06-01

    A version of the National Center for Atmospheric Research community climate model — a global, spectral (R15) general circulation model — is coupled to a coarse-grid (5° latitude-] longitude, four-layer) ocean general circulation model to study the response of the climate system to increases of atmospheric carbon dioxide (CO2). Three simulations are run: one with an instantaneous doubling of atmospheric CO2 (from 330 to 660 ppm), another with the CO2 concentration starting at 330 ppm and increasing linearly at a rate of 1% per year, and a third with CO2 held constant at 330 pm. Results at the end of 30 years of simulation indicate a globally averaged surface air temperature increase of 1.6° C for the instantaneous doubling case and 0.7°C for the transient forcing case. Inherent characteristics of the coarse-grid ocean model flow sea-surface temperatures (SSTs) in the tropics and higher-than-observed SSTs and reduced sea-ice extent at higher latitudes] produce lower sensitivity in this model after 30 years than in earlier simulations with the same atmosphere coupled to a 50-m, slab-ocean mixed layer. Within the limitations of the simulated meridional overturning, the thermohaline circulation weakens in the coupled model with doubled CO2 as the high-latitude ocean-surface layer warms and freshens and westerly wind stress is decreased. In the transient forcing case with slowly increasing CO2 (30% increase after 30 years), the zonal mean warming of the ocean is most evident in the surface layer near 30° 50° S. Geographical plots of surface air temperature change in the transient case show patterns of regional climate anomalies that differ from those in the instantaneous CO2 doubling case, particularly in the North Atlantic and northern European regions. This suggests that differences in CO2 forcing in the climate system are important in CO2 response in regard to time-dependent climate anomaly regimes. This confirms earlier studies with simple climate models

  17. Reversal of global atmospheric ethane and propane trends largely due to US oil and natural gas production

    Science.gov (United States)

    Helmig, Detlev; Rossabi, Samuel; Hueber, Jacques; Tans, Pieter; Montzka, Stephen A.; Masarie, Ken; Thoning, Kirk; Plass-Duelmer, Christian; Claude, Anja; Carpenter, Lucy J.; Lewis, Alastair C.; Punjabi, Shalini; Reimann, Stefan; Vollmer, Martin K.; Steinbrecher, Rainer; Hannigan, James W.; Emmons, Louisa K.; Mahieu, Emmanuel; Franco, Bruno; Smale, Dan; Pozzer, Andrea

    2016-07-01

    Non-methane hydrocarbons such as ethane are important precursors to tropospheric ozone and aerosols. Using data from a global surface network and atmospheric column observations we show that the steady decline in the ethane mole fraction that began in the 1970s halted between 2005 and 2010 in most of the Northern Hemisphere and has since reversed. We calculate a yearly increase in ethane emissions in the Northern Hemisphere of 0.42 (+/-0.19) Tg yr-1 between mid-2009 and mid-2014. The largest increases in ethane and the shorter-lived propane are seen over the central and eastern USA, with a spatial distribution that suggests North American oil and natural gas development as the primary source of increasing emissions. By including other co-emitted oil and natural gas non-methane hydrocarbons, we estimate a Northern Hemisphere total non-methane hydrocarbon yearly emission increase of 1.2 (+/-0.8) Tg yr-1. Atmospheric chemical transport modelling suggests that these emissions could augment summertime mean surface ozone by several nanomoles per mole near oil and natural gas production regions. Methane/ethane oil and natural gas emission ratios could suggest a significant increase in associated methane emissions; however, this increase is inconsistent with observed leak rates in production regions and changes in methane's global isotopic ratio.

  18. Measurement of the Atmospheric $\

    CERN Document Server

    Aartsen, M G; Abdou, Y; Ackermann, M; Adams, J; Aguilar, J A; Ahlers, M; Altmann, D; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Baum, V; Bay, R; Beattie, K; Beatty, J J; Bechet, S; Tjus, J Becker; Becker, K -H; Bell, M; Benabderrahmane, M L; BenZvi, S; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohaichuk, S; Bohm, C; Bose1, D; Boser, S; Botner, O; Brayeur, L; Brown, A M; Bruijn, R; Brunner, J; Buitink, S; Carson, M; Casey, J; Casier, M; Chirkin, D; Christy, B; Clark, K; Clevermann, F; Cohen, S; Cowen, D F; Silva, A H Cruz; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; De Ridder, S; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; Diaz-Velez, J C; Dreyer, J; Dumm, J P; Dunkman, M; Eagan, R; Eberhardt, B; Eisch, J; Ellsworth, R W; Engdegard, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feintzeig, J; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Flis, S; Franckowiak, A; Franke, R; Frantzen, K; Fuchs, T; Gaisser, T K; Gallagher, J; Gerhardt, L; Gladstone, L; Glusenkamp, T; Goldschmidt, A; Golup, G; Goodman, J A; Gora, D; Grant, D; Gross, A; Grullon, S; Gurtner, M; Ha, C; Ismail, A Haj; Hallgren, A; Halzen, F; Hanson, K; Heereman, D; Heimann, P; Heinen, D; Helbing, K; Hellauer, R; Hickford, S; Hill, G C; Hoffman, K D; Hoffmann, R; Homeier, A; Hoshina, K; Huelsnitz, W; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobi, E; Jacobsen, J; Japaridze, G S; Jlelati, O; Kappes, A; Karg, T; Karle, A; Kiryluk, J; Kislat, F; Klas, J; Klein, S R; Kohne, J -H; Kohnen, G; Kolanoski, H; Kopke, L; Kopper, C; Kopper, S; Koskinen, D J; Kowalski, M; Krasberg, M; Kroll, G; Kunnen, J; Kurahashi, N; Kuwabara, T; Labare, M; Landsman, H; Larson, M J; Lauer, R; Lesiak-Bzdak, M; Lunemann, J; Madsen, J; Maruyama, R; Mase, K; Matis, H S; McNally, F; Meagher, K; Merck, M; Meszaros, P; Meures, T; Miarecki, S; Middell, E; Milke, N; Miller, J; Mohrmann, L; Montaruli, T; Morse, R; Nahnhauer, R; Naumann, U; Nowicki, S C; Nygren, D R; Obertacke, A; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Panknin, S; Paul, L; Pepper, J A; Heros, C Perez de los; Pieloth, D; Pirk, N; Posselt, J; Price, P B; Przybylski, G T; Radel, L; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Richman, M; Riedel, B; Rodrigues, J P; Rott, C; Ruhe, T; Ruzybayev, B; Ryckbosch, D; Saba, S M; Salameh, T; Sander, H -G; Santander, M; Sarkar, S; Schatto, K; Scheel, M; Scheriau, F; Schmidt, T; Schmitz, M; Schoenen, S; Schoneberg, S; Schonherr, L; Schonwald, A; Schukraft, A; Schulte, L; Schulz, O; Seckel, D; Seo, S H; Sestayo, Y; Seunarine, S; Sheremata, C; Smith, M W E; Soiron, M; Soldin, D; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stasik, A; Stezelberger, T; Stokstad, R G; Stoss, A; Strahler, E A; Strom, R; Sullivan, G W; Taavola, H; Taboada, I; Tamburro, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Usner, M; van der Drift, D; van Eijndhoven, N; Van Overloop, A; van Santen, J; Vehring, M; Voge1, M; Vraeghe, M; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Wasserman, R; Weaver, Ch; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wissing, H; Wolf, M; Wood, T R; Woschnagg, K; Xu, C; Xu, D L; Xu, X W; Yanez, J P; Yodh, G; Yoshida, S; Zarzhitsky, P; Ziemann, J; Zierke, S; Zilles, A; Zoll, M

    2012-01-01

    We report the first observation in a high energy neutrino telescope of cascades induced by atmospheric electron neutrinos and by neutral current interactions of atmospheric neutrinos of all flavors. Using data recorded during the first year of operation of IceCube's DeepCore low energy extension, a sample of 1029 events is observed in 281 days of data. The number of observed cascades is $N_{\\rm cascade} = 496 \\pm 66 (stat.) \\pm 88(syst.)$ and the rest of the sample consists of residual backgrounds due to atmospheric muons and charged current interactions of atmospheric muon neutrinos. The flux of the atmospheric electron neutrinos is determined in the energy range between approximately 80 GeV and 6 TeV and is consistent with models of atmospheric neutrinos.

  19. Numerical study of the electron and muon lateral distribution in atmospheric showers of high energy cosmic rays

    Science.gov (United States)

    Georgios, Atreidis

    2017-03-01

    The lateral distribution of an atmospheric shower depends on the characteristics of the high energy interactions and the type of the primary particle. The influence of the primary particle in the secondary development of the shower into the atmosphere, is studied by analyzing the lateral distribution of electron and muon showers having as primary particle, proton, photon or iron nucleus. This study of the lateral distribution can provide useful conclusions for the mass and energy of the primary particle. This paper compares the data that we get from simulations with CORSIKA program with experimental data and the theoretical NKG function expressing lateral electron and muon distribution. Then we modify the original NKG function to fit better to the simulation data and propose a method for determining the mass of the original particle started the atmospheric shower.

  20. First in situ evidence of electron pitch angle scattering due to magnetic field line curvature in the Ion diffusion region

    Science.gov (United States)

    Zhang, Y. C.; Shen, C.; Marchaudon, A.; Rong, Z. J.; Lavraud, B.; Fazakerley, A.; Yao, Z.; Mihaljcic, B.; Ji, Y.; Ma, Y. H.; Liu, Z. X.

    2016-05-01

    Theory predicts that the first adiabatic invariant of a charged particle may be violated in a region of highly curved field lines, leading to significant pitch angle scattering for particles whose gyroradius are comparable to the radius of the magnetic field line curvature. This scattering generates more isotropic particle distribution functions, with important impacts on the presence or absence of plasma instabilities. Using magnetic curvature analysis based on multipoint Cluster spacecraft observations, we present the first investigation of magnetic curvature in the vicinity of an ion diffusion region where reconnected field lines are highly curved. Electrons at energies > 8 keV show a clear pitch angle ordering between bidirectional and trapped distribution in surrounding regions, while we show that in the more central part of the ion diffusion region electrons above such energies become isotropic. By contrast, colder electrons (~1 keV) retain their bidirectional character throughout the diffusion regions. The calculated adiabatic parameter K2 for these electrons is in agreement with theory. This study provides the first observational evidence for particle pitch angle scattering due to magnetic field lines with well characterized curvature in a space plasma.

  1. Resuspension and atmospheric transport of radionuclides due to wildfires near the Chernobyl Nuclear Power Plant in 2015: An impact assessment

    Science.gov (United States)

    Evangeliou, N.; Zibtsev, S.; Myroniuk, V.; Zhurba, M.; Hamburger, T.; Stohl, A.; Balkanski, Y.; Paugam, R.; Mousseau, T. A.; Møller, A. P.; Kireev, S. I.

    2016-05-01

    In April and August 2015, two major fires in the Chernobyl Exclusion Zone (CEZ) caused concerns about the secondary radioactive contamination that might have spread over Europe. The present paper assessed, for the first time, the impact of these fires over Europe. About 10.9 TBq of 137Cs, 1.5 TBq of 90Sr, 7.8 GBq of 238Pu, 6.3 GBq of 239Pu, 9.4 GBq of 240Pu and 29.7 GBq of 241Am were released from both fire events corresponding to a serious event. The more labile elements escaped easier from the CEZ, whereas the larger refractory particles were removed more efficiently from the atmosphere mainly affecting the CEZ and its vicinity. During the spring 2015 fires, about 93% of the labile and 97% of the refractory particles ended in Eastern European countries. Similarly, during the summer 2015 fires, about 75% of the labile and 59% of the refractory radionuclides were exported from the CEZ with the majority depositing in Belarus and Russia. Effective doses were above 1 mSv y-1 in the CEZ, but much lower in the rest of Europe contributing an additional dose to the Eastern European population, which is far below a dose from a medical X-ray.

  2. Further observations of a decreasing atmospheric CO2 uptake capacity in the Canada Basin (arctic Ocean) due to sea ice loss

    DEFF Research Database (Denmark)

    Else, B.G.T.; Galley, R.J.; Lansard, B.

    2013-01-01

    [1] Using data collected in 2009, we evaluated the potential for the southeastern Canada Basin (Arctic Ocean) to act as an atmospheric CO2 sink under the summertime ice-free conditions expected in the near future. Beneath a heavily decayed ice cover, we found surprisingly high pCO2sw (~290–320matm......), considering that surface water temperatures were low and the influence of ice melt was strong. A simple model simulating melt of the remaining ice and exposure of the surface water for 100 days revealed a weak capacity for atmospheric CO2 uptake (mean flux: 2.4 mmol m2 d1), due largely to warming of the shallow....... Galley, B. Lansard, D. G. Barber, K. Brown, L. A. Miller, A. Mucci, T. N. Papakyriakou, J.-É. Tremblay, and S. Rysgaard (2013), Further observations of a decreasing atmospheric CO2 uptake capacity in the Canada Basin (Arctic Ocean) due to sea ice loss, Geophys. Res. Lett., 40, 1132–1137, doi:10.1002/grl...

  3. Differential conductance of armchair single-wall carbon nanotubes due to presence of electron-phonon interaction

    Science.gov (United States)

    Tajik, Fatemeh; Namiranian, Afshin

    2016-10-01

    We have theoretically investigated the first correction to conductance of armchair single wall carbon nanotubes (SWCNTs) with finite length, embedded between two electrodes, due to the presence of electron-transversal phonon interaction. The perturbative scheme has been used with finite length real space nearest neighbors tight binding method. Both radial breathing and tangential modes are investigated separately. It is found that not only the conductance correction crucially depends on source-drain voltage but also it strongly depends on the length and diameter of SWCNT. So, this work opens up opportunities to control the electrical conductance of SWCNT and increases yield of micro or nanodevices based on carbon nanotube.

  4. Modification of spacecraft charging and the near-plasma environment caused by the interaction of an artificial electron beam with the earth's upper atmosphere

    DEFF Research Database (Denmark)

    Neubert, Torsten; Banks, P. M.; Gilchrist, B.E.

    1991-01-01

    The Beam-Atmosphere Interaction (BAI) involves the ionization created in the earth's upper atmosphere by electron beams emitted from a low altitude spacecraft. This process is described by two coupled non-linear differential electron transport equations for the up-going (along magnetic field line...

  5. Parametric studies with an atmospheric diffusion model that assesses toxic fuel hazards due to the ground clouds generated by rocket launches

    Science.gov (United States)

    Stewart, R. B.; Grose, W. L.

    1975-01-01

    Parametric studies were made with a multilayer atmospheric diffusion model to place quantitative limits on the uncertainty of predicting ground-level toxic rocket-fuel concentrations. Exhaust distributions in the ground cloud, cloud stabilized geometry, atmospheric coefficients, the effects of exhaust plume afterburning of carbon monoxide CO, assumed surface mixing-layer division in the model, and model sensitivity to different meteorological regimes were studied. Large-scale differences in ground-level predictions are quantitatively described. Cloud alongwind growth for several meteorological conditions is shown to be in error because of incorrect application of previous diffusion theory. In addition, rocket-plume calculations indicate that almost all of the rocket-motor carbon monoxide is afterburned to carbon dioxide CO2, thus reducing toxic hazards due to CO. The afterburning is also shown to have a significant effect on cloud stabilization height and on ground-level concentrations of exhaust products.

  6. Electron density change of atmospheric-pressure plasmas in helium flow depending on the oxygen/nitrogen ratio of the surrounding atmosphere

    Science.gov (United States)

    Tomita, Kentaro; Urabe, Keiichiro; Shirai, Naoki; Sato, Yuta; Hassaballa, Safwat; Bolouki, Nima; Yoneda, Munehiro; Shimizu, Takahiro; Uchino, Kiichiro

    2016-06-01

    Laser Thomson scattering was applied to an atmospheric-pressure plasma produced in a helium (He) gas flow for measuring the spatial profiles of electron density (n e) and electron temperature (T e). Aside from the He core flow, the shielding gas flow of N2 or synthesized air (\\text{N}2:\\text{O}2 = 4:1) surrounding the He flow was introduced to evaluate the effect of ambient gas components on the plasma parameters, eliminating the effect of ambient humidity. The n e at the discharge center was 2.7 × 1021 m-3 for plasma generated with N2/O2 shielding gas, 50% higher than that generated with N2 shielding.

  7. Visions of Our Planet's Atmosphere, Land and Oceans Electronic-Theater 2001

    Science.gov (United States)

    Hasler, A. F.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    The NASA/NOAA/AMS Electronic Theater presents Earth science observations and visualizations in a historical perspective. Fly in from outer space to Fredericton New Brunswick. Drop in on the Kennedy Space Center and Park City Utah, site of the 2002 Olympics using 1 m IKONOS "Spy Satellite" data. Go back to the early weather satellite images from the 1960s and see them contrasted with the latest US and International global satellite weather movies including hurricanes & tornadoes. See the latest spectacular images from NASA/NOAA and Canadian remote sensing missions like Terra GOES, TRMM, SeaWiFS, Landsat 7, and Radarsat that are visualized & explained. See how High Definition Television (HDTV) is revolutionizing the way we communicate science in cooperation with the American Museum of Natural History in NYC. See dust storms in Africa and smoke plumes from fires in Mexico. See visualizations featured on Newsweek, TIME, National Geographic, Popular Science covers & National & International Network TV. New visualization tools allow us to roam & zoom through massive global images eg Landsat tours of the US, Africa, & New Zealand showing desert and mountain geology as well as seasonal changes in vegetation. See animations of the polar ice packs and the motion of gigantic Antarctic Icebergs from SeaWinds data. Spectacular new visualizations of the global atmosphere & oceans are shown. See massive dust storms sweeping across Africa. See vortexes and currents in the global oceans that bring up the nutrients to feed tiny plankton and draw the fish, whales and fisherman. See the how the ocean blooms in response to these currents and El Nino/La Nina climate changes. The demonstration is interactively driven by a SGI Onyx II Graphics Supercomputer with four CPUs, 8 Gigabytes of RAM and Terabyte of disk. With multiple projectors on a giant screen. See the city lights, fishing fleets, gas flares and bio-mass burning of the Earth at night observed by the "night-vision" DMSP

  8. Close-coupling calculations of fine-structure excitation of Ne II due to H and electron collisions

    Science.gov (United States)

    Stancil, Phillip C.; Cumbee, Renata; Wang, Qianxia; Loch, Stuart; Pindzola, Michael; Schultz, David R.; Buenker, Robert; McLaughlin, Brendan; Ballance, Connor

    2016-06-01

    Fine-structure transitions within the ground term of ions and neutral atoms dominate the cooling in a variety of molecular regions and also provide important density and temperature diagnostics. While fine-structure rates due to electron collisions have been studied for many systems, data are generally sparse for elements larger than oxygen, at low temperatures, and for collisions due to heavy particles. We provide rate coefficients for H collisions for the first time. The calculations were performed using the quantum molecular-orbital close-coupling approach and the elastic approximation. The heavy-particle collisions use new potential energies for the lowest-lying NeH+ states computed with the MRDCI method. The focus of the electron-impact calculations is to provide fine-structure excitation rate coefficients down to 10 K. We compare with previous calculations at higher temperatures (Griffin et al. 2001), and use a range of calculations to provide an estimate of the uncertainty on our recommended rate coefficients. A brief discussion of astrophysical applications is also provided.Griffin, D.C., et al., 2001, J. Phys. B, 34, 4401This work partially supported by NASA grant No. NNX15AE47G.

  9. Enhancement in electron and ion temperatures due to solar flares as measured by SROSS-C2 satellite

    Directory of Open Access Journals (Sweden)

    D. K. Sharma

    2004-06-01

    Full Text Available The observations on the ionospheric electron and ion temperatures (Te and Ti measured by the RPA payload aboard the SROSS-C2 satellite have been used to study the effect of solar flares on ionospheric heating. The data on solar flare has been obtained from the National Geophysical Data Center (NGDC Boulder, Colorado (USA. It has been found that the electron and ion temperatures have a consistent enhancement during the solar flares on the dayside Earth's ionosphere. The estimated enhancement for the average electron temperature is from 1.3 to 1.9 times whereas for ion temperature it is from 1.2 to 1.4 times to the normal days average temperature. The enhancement of ionospheric temperatures due to solar flares is correlated with the diurnal variation of normal days' ionospheric temperatures. The solar flare does not have any significant effect on the nightside ionosphere. A comparison with the temperature obtained from the IRI-95 model also shows a similar enhancement.

  10. Online diagnosis of electron excitation temperature in CH4+H2 discharge plasma at atmospheric pressure by optical emission spectra

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Methane coupling under low temperature plasmas at atmospheric pressure is a green process by use of renewable sources of energy. In this study, CH4+H2 dis- charge plasma was on-line diagnosed by optical emission spectra so as to char- acterize the discharge system and to do spade work for the optimization of the technical parameters for future commercial production of methane coupling under plasmas. The study was focused on a calculation method for the online diagnosis of the electron excitation temperature in CH4+H2 discharge plasma at atmospheric pressure. The diagnostic method is easy, efficient and fairly precise. A serious er- ror in a literature was corrected during the reasoning of its series of equations formerly used to calculate electron temperatures in plasmas.

  11. Online diagnosis of electron excitation temperature in CH4+H2 discharge plasma at atmospheric pressure by optical emission spectra

    Institute of Scientific and Technical Information of China (English)

    CUI JinHua; XU ZhenFeng; ZHANG JiaLiang; NIE QiuYue; XU GenHui; REN LongLiang

    2008-01-01

    Methane coupling under low temperature plasmas at atmospheric pressure is a green process by use of renewable sources of energy.In this study,CH4+H2 dis-charge plasma was on-line diagnosed by optical emission spectra so as to char-acterize the discharge system and to do spade work for the optimization of the technical parameters for future commercial production of methane coupling under plasmas.The study was focused on a calculation method for the online diagnosis of the electron excitation temperature in CH4+H2 discharge plasma at atmospheric pressure.The diagnostic method is easy,efficient and fairly precise.A serious er-ror in a literature was corrected during the reasoning of its series of equations formerly used to calculate electron temperatures in plasmas.

  12. Application of diffuse discharges of atmospheric pressure formed by runaway electrons for modification of copper and stainless steel surface

    Energy Technology Data Exchange (ETDEWEB)

    Tarasenko, V. F., E-mail: VFT@loi.hcei.tsc.ru; Shulepov, M. A.; Erofeev, M. V. [Russian Academy of Sciences, Institute of High Current Electronics, Siberian Branch (Russian Federation)

    2015-12-15

    The results of studies devoted to the influence of a runaway electron pre-ionized diffuse discharge (REP DD) formed in air and nitrogen at atmospheric pressure on the surface of copper and stainless steel are presented. Nanosecond high-voltage pulses were used to obtain REP DD in different gases at high pressures in a chamber with a flat anode and a cathode possessing a small radius of curvature. This mode of discharge was implemented owing to the generation of runaway electrons and X-rays. The conditions under which the surface of copper and stainless steel was cleaned from carbon and oxidized are described.

  13. Damage induced to DNA by low-energy (0-30 eV) electrons under vacuum and atmospheric conditions.

    Science.gov (United States)

    Brun, Emilie; Cloutier, Pierre; Sicard-Roselli, Cécile; Fromm, Michel; Sanche, Léon

    2009-07-23

    In this study, we show that it is possible to obtain data on DNA damage induced by low-energy (0-30 eV) electrons under atmospheric conditions. Five monolayer films of plasmid DNA (3197 base pairs) deposited on glass and gold substrates are irradiated with 1.5 keV X-rays in ultrahigh vacuum and under atmospheric conditions. The total damage is analyzed by agarose gel electrophoresis. The damage produced on the glass substrate is attributed to energy absorption from X-rays, whereas that produced on the gold substrate arises from energy absorption from both the X-ray beam and secondary electrons emitted from the gold surface. By analysis of the energy of these secondary electrons, 96% are found to have energies below 30 eV with a distribution peaking at 1.4 eV. The differences in damage yields recorded with the gold and glass substrates is therefore essentially attributed to the interaction of low-energy electrons with DNA under vacuum and hydrated conditions. From these results, the G values for low-energy electrons are determined to be four and six strand breaks per 100 eV, respectively.

  14. Non-Maxwellian electron distribution functions due to self-generated turbulence in collisionless guide-field reconnection

    Science.gov (United States)

    Muñoz, P. A.; Büchner, J.

    2016-10-01

    Non-Maxwellian electron velocity space distribution functions (EVDFs) are useful signatures of plasma conditions and non-local consequences of collisionless magnetic reconnection. In the past, EVDFs were obtained mainly for antiparallel reconnection and under the influence of weak guide-fields in the direction perpendicular to the reconnection plane. EVDFs are, however, not well known, yet, for oblique (or component-) reconnection in case and in dependence on stronger guide-magnetic fields and for the exhaust (outflow) region of reconnection away from the diffusion region. In view of the multi-spacecraft Magnetospheric Multiscale Mission (MMS), we derived the non-Maxwellian EVDFs of collisionless magnetic reconnection in dependence on the guide-field strength bg from small ( b g ≈ 0 ) to very strong (bg = 8) guide-fields, taking into account the feedback of the self-generated turbulence. For this sake, we carried out 2.5D fully kinetic Particle-in-Cell simulations using the ACRONYM code. We obtained anisotropic EVDFs and electron beams propagating along the separatrices as well as in the exhaust region of reconnection. The beams are anisotropic with a higher temperature in the direction perpendicular rather than parallel to the local magnetic field. The beams propagate in the direction opposite to the background electrons and cause instabilities. We also obtained the guide-field dependence of the relative electron-beam drift speed, threshold, and properties of the resulting streaming instabilities including the strongly non-linear saturation of the self-generated plasma turbulence. This turbulence and its non-linear feedback cause non-adiabatic parallel electron acceleration. We further obtained the resulting EVDFs due to the non-linear feedback of the saturated self-generated turbulence near the separatrices and in the exhaust region of reconnection in dependence on the guide field strength. We found that the influence of the self-generated plasma turbulence

  15. Electronic-Theater 2001: Visions of Our Planet's Atmosphere, Land and Oceans

    Science.gov (United States)

    Hasler, Authur; Starr, David OC. (Technical Monitor)

    2001-01-01

    The NASA/NOAA/AMS Electronic Theater presents Earth science observations and visualizations in a historical perspective. Fly in from outer space to Wisconsin, Madison and the Monona Terrace Center. Drop in on the Kennedy Space Center and Park City Utah, site of the 2002 Olympics using I m IKONOS "Spy Satellite" data. Go back to the early weather satellite images from the 1960s pioneered by UW. Scientists and see them contrasted with the latest US and International global satellite weather movies including hurricanes & tornadoes. See the latest spectacular images from NASA/NOAA remote sensing missions like Terra GOES, TRMM, SeaWiFS, Landsat 7 that are visualized & explained. See how High Definition Television (HDTV) is revolutionizing the way we communicate science in cooperation with the American Museum of Natural History in NYC. See dust storms in Africa and smoke plumes from fires in Mexico. See visualizations featured on Newsweek, TIME, National Geographic, Popular Science covers & National & International Network TV. New visualization tools allow us to roam & zoom through massive global images eg Landsat tours of the US, Africa, & New Zealand showing desert and mountain geology as well as seasonal changes in vegetation. See animations of the polar ice packs and the motion of gigantic Antarctic Icebergs from SeaWinds data. Spectacular new visualizations of the global atmosphere & oceans are shown. See massive dust storms sweeping across Africa. See vortices and currents in the global oceans that bring up the nutrients to feed tiny plankton and draw the fish, whales and fisherman. See the how the ocean blooms in response to these currents and El Nina/La Nina climate changes. The demonstration is interactively driven by a SGI Onyx 11 Graphics Supercomputer with four CPUs, 8 Gigabytes of RAM and Terabyte of disk. With five projectors on a giant IMAX sized 18 x 72 ft screen. See the city lights, fishing fleets, gas flares and bio-mass burning of the Earth at night

  16. Visions of our Planet's Atmosphere, Land and Oceans: NASA/NOAA Electronic Theater 2002

    Science.gov (United States)

    Hasler, A. F.; Starr, David (Technical Monitor)

    2002-01-01

    The NASA/NOAA Electronic Theater presents Earth science observations and visualizations in a historical perspective. Fly in from outer space to the Olympic Medals Plaza, the new Gateway Center, and the University of Utah Stadium Site of the Olympic Opening and Closing Ceremonies in Salt Lake City. Fly in and through the Park City, and Snow Basin sites of the 2002 Winter Olympic Alpine Venues using 1 m IKONOS "Spy Satellite" data. See the four seasons of the Wasatch Front as observed by Landsat 7 at 15m resolution and watch the trees turn color in the Fall, snow come and go in the mountains and the reservoirs freeze and melt. Go back to the early weather satellite images from the 1960s and see them contrasted with the latest US and international global satellite weather movies Including hurricanes & "tornadoes". See the latest visualizations of spectacular images from NASA/NOAA remote sensing missions like Terra, GOES, TRMM, SeaWiFS, Landsat 7 including new 1 - min GOES rapid scan image sequences of Nov 9th 2001 Midwest tornadic thunderstorms and have them explained. See how High-Definition Television (HDTV) is revolutionizing the way we communicate science. (In cooperation with the American Museum of Natural History in NYC) See dust storms in Africa and smoke plumes from fires in Mexico. See visualizations featured on the covers Of Newsweek, TIME, National Geographic, Popular Science & on National & International Network TV. New computer software. tools allow us to roam & zoom through massive global images e.g. Landsat tours of the US, and Africa, showing desert and mountain geology as well as seasonal changes in vegetation. See animations of the polar ice packs and the motion of gigantic Antarctic Icebergs from SeaWinds data. Spectacular new visualizations of the global atmosphere & oceans are shown. See vertexes and currents in the global oceans that bring up the nutrients to feed tin) algae and draw the fish, whales and fisherman. See the how the ocean blooms in

  17. Nonmonotonous electron mobility due to structurally induced resonant coupling of subband states in an asymmetric double quantum well

    Energy Technology Data Exchange (ETDEWEB)

    Nayak, R. K.; Das, S.; Panda, A. K.; Sahu, T., E-mail: tsahu-bu@rediffmail.com [Department of Electronics and Communication Engineering, National Institute of Science and Technology, Palur Hills, Berhampur-761 008, Odisha (India)

    2015-11-15

    We show that sharp nonmonotic variation of low temperature electron mobility μ can be achieved in GaAs/Al{sub x}Ga{sub 1-x}As barrier delta-doped double quantum well structure due to quantum mechanical transfer of subband electron wave functions within the wells. We vary the potential profile of the coupled structure as a function of the doping concentration in order to bring the subbands into resonance such that the subband energy levels anticross and the eigen states of the coupled structure equally share both the wells thereby giving rise to a dip in mobility. When the wells are of equal widths, the dip in mobility occurs under symmetric doping of the side barriers. In case of unequal well widths, the resonance can be obtained by suitable asymmetric variation of the doping concentrations. The dip in mobility becomes sharp and also the wavy nature of mobility takes a rectangular shape by increasing the barrier width. We show that the dip in mobility at resonance is governed by the interface roughness scattering through step like changes in the subband mobilities. It is also gratifying to show that the drop in mobility at the onset of occupation of second subband is substantially supressed through the quantum mechanical transfer of subband wave functions between the wells. Our results can be utilized for performance enhancement of coupled quantum well devices.

  18. Energy Loss of Solar $p$ Modes due to the excitation of Magnetic Sausage Tube Waves: Importance of Coupling the Upper Atmosphere

    CERN Document Server

    Gascoyne, Andrew; Hindman, Bradley

    2014-01-01

    We consider damping and absorption of solar $p$ modes due to their energy loss to magnetic tube waves that can freely carry energy out of the acoustic cavity. The coupling of $p$ modes and sausage tube waves is studied in a model atmosphere composed of a polytropic interior above which lies an isothermal upper atmosphere. The sausage tube waves, excited by $p$ modes, propagate along a magnetic fibril which is assumed to be a vertically aligned, stratified, thin magnetic flux-tube. The deficit of $p$-mode energy is quantified through the damping rate, $\\Gamma$ and absorption coefficient, $\\alpha$. The variation of $\\Gamma$ and $\\alpha$ as a function of frequency and the tube's plasma properties is studied in detail. Previous similar studies have considered only a subphotospheric layer, modelled as a polytrope that has been truncated at the photosphere (Bogdan et al. (1996), Hindman & Jain 2008, Gascoyne et al. (2011)). Such studies have found that the resulting energy loss by the $p$ modes is very sensitiv...

  19. Electron impact ionization and attachment cross sections for H2S. [in comet and planetary atmospheres

    Science.gov (United States)

    Rao, M. V. V. S.; Srivastava, S. K.

    1993-01-01

    Experiments were performed to measure, by electron impact, appearance potentials and the cross sections for ionization, dissociative ionization, and electron attachment for H2S. Results are presented, and discussed individually, for both positive and negative ions. A schematic diagram of the experimental setup is included.

  20. Electron properties and air mixing in radio frequency driven argon plasma jets at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Gessel, Bram van; Bruggeman, Peter [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Brandenburg, Ronny [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, D-17489 Greifswald (Germany)

    2013-08-05

    A time modulated radio frequency (RF) plasma jet operated with an Ar mixture is investigated by measuring the electron density and electron temperature using Thomson scattering. The measurements have been performed spatially resolved for two different electrode configurations and as a function of the plasma dissipated power and air concentration admixed to the Ar. Time resolved measurements of electron densities and temperatures during the RF cycle and after plasma power switch-off are presented. Furthermore, the influence of the plasma on the air entrainment into the effluent is studied using Raman scattering.

  1. Nighttime D region electron density measurements from ELF-VLF tweek radio atmospherics recorded at low latitudes

    OpenAIRE

    İnan, Umran Savaş; Maurya, Ajeet K.; Veenadhari, B. ; Singh, Rajesh ; Kumar, Sushil ; Cohen, M. B. ; Selvakumaran, R. ; Gokani, Sneha ; Pant, P.; Singh, A. K.

    2012-01-01

    Dispersive atmospherics (tweeks) observed during 2010 simultaneously at two low-latitude stations, Allahabad (geomagnetic latitude, 16.05 N) and Nainital (geomagnetic latitude, 20.48 N), have been used to estimate the nighttime D region electron density at the ionospheric reflection height under the local nighttime propagation (21:00–02:00 LT or 15:30–20:30 UT). The analysis of simultaneously recorded tweeks at both the stations on five international quiet days during one month...

  2. Atmospheric Neutrinos

    OpenAIRE

    Takaaki Kajita

    1994-01-01

    Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron-neutrinos and muon-neutrinos are produced mainly by the decay chain of charged pions to muons to electrons. Atmospheric neutrino experiments observed zenith angle and energy-dependent deficit of muon-neutrino events. It was found that neutrino oscillations between muon-neutrinos and tau-neutrinos explain these data well. This paper discusses...

  3. Electron attachment to molecules and clusters of atmospheric relevance: oxygen and ozone

    Science.gov (United States)

    Matejcik, S.; Kiendler, A.; Cicman, P.; Skalny, J.; Stampfli, P.; Illenberger, E.; Chu, Y.; Stamatovic, A.; Märk, T. D.

    1997-05-01

    Highly monochromatized electrons are used in a crossed beams experiment to investigate electron attachment to oxygen clusters 0963-0252/6/2/007/img1 at electron energies from approximately zero up to 2 eV. At energies close to zero the attachment cross section for the reaction 0963-0252/6/2/007/img2 varies inversely with the electron energy, indicative of s-wave electron capture to 0963-0252/6/2/007/img1. Peaks in the attachment cross section present at higher energies can be ascribed to vibrational levels of the oxygen anion. The vibrational spacings observed can be quantitatively accounted for. In addition, electron attachment to ozone and mixed oxygen/ozone clusters has been studied in the energy range up to 4 eV. Absolute attachment cross sections for both fragment ions, 0963-0252/6/2/007/img4 and 0963-0252/6/2/007/img5, from ozone could be deduced. Moreover, despite the initially large excess of oxygen molecules in the neutral oxygen/ozone clusters the dominant attachment products are undissociated clusters ions 0963-0252/6/2/007/img6 including the 0963-0252/6/2/007/img7 monomer while oxygen ions 0963-0252/6/2/007/img8 appear with comparatively low intensity.

  4. Microbial radio-resistance of Salmonella Typhimurium in egg increases due to repetitive irradiation with electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Tesfai, Adiam T.; Beamer, Sarah K.; Matak, Kristen E. [West Virginia University, Division of Animal and Nutritional Sciences, PO Box 6108, Morgantown, WV 26508 (United States); Jaczynski, Jacek, E-mail: Jacek.Jaczynski@mail.wvu.ed [West Virginia University, Division of Animal and Nutritional Sciences, PO Box 6108, Morgantown, WV 26508 (United States)

    2011-04-15

    Ionizing radiation improves food safety. However, foodborne pathogens develop increased resistance in response to sub-lethal stresses such as heat, pH, antibiotics, etc. Therefore, it is hypothesized that foodborne pathogens may develop increased radio-resistance to electron beam (e-beam) radiation. The objective was to determine if D{sub 10}-value for Salmonella Typhimurium in de-shelled raw egg (egg white and yolk mixed together) increases due to repetitive processing with e-beam at sub-lethal doses. Survivors were enumerated on non-selective (TSA) and selective (XLD) media. Survivors from the highest dose were isolated and used in subsequent e-beam cycle. This process was repeated four times for a total of five e-beam cycles. D{sub 10}-values for S. Typhimurium enumerated on TSA and XLD following each e-beam cycle were calculated as inverse reciprocal of the slope of survivor curves. D{sub 10}-values for the ATCC strain were 0.59{+-}0.031 and 0.46{+-}0.022 kGy on TSA and XLD, respectively. However, following the fifth e-beam cycle, the respective D{sub 10}-values increased (P<0.05) to 0.69{+-}0.026 and 0.61{+-}0.029 kGy, respectively. S. Typhimurium showed a trend (P>0.05) to develop radio-resistance faster on selective media, likely due to facilitated selection of radio-resistant cells within microbial population following each e-beam cycle. For all five e-beam cycles, S. Typhimurium had higher (P<0.05) D{sub 10}-values on non-selective media, indicating that sub-lethal injury followed by cellular repair and recovery are important for radio-resistance and inactivation of this microorganism. This study demonstrated that e-beam efficiently inactivates S. Typhimurium in raw egg; however, similar to other inactivation techniques and factors affecting microbial growth, S. Typhimurium develops increased radio-resistance if repetitively processed with e-beam at sub-lethal doses.

  5. The Ocean Colour Climate Change Initiative: II. Spatial and Temporal Homogeneity of Satellite Data Retrieval Due to Systematic Effects in Atmospheric Correction Processors

    Science.gov (United States)

    Muller, Dagmar; Krasemann, Hajo; Brewin, Robert J. W.; Brockmann, Carsten; Deschamps, Pierre-Yves; Fomferra, Norman; Franz, Bryan A.; Grant, Mike G.; Groom, Steve B.; Melin, Frederic; Platt, Trevor; Regner, Peter; Sathyendranath, Shubha; Steinmetz, Francois; Swinton, John

    2015-01-01

    The established procedure to access the quality of atmospheric correction processors and their underlying algorithms is the comparison of satellite data products with related in-situ measurements. Although this approach addresses the accuracy of derived geophysical properties in a straight forward fashion, it is also limited in its ability to catch systematic sensor and processor dependent behaviour of satellite products along the scan-line, which might impair the usefulness of the data in spatial analyses. The Ocean Colour Climate Change Initiative (OC-CCI) aims to create an ocean colour dataset on a global scale to meet the demands of the ecosystem modelling community. The need for products with increasing spatial and temporal resolution that also show as little systematic and random errors as possible, increases. Due to cloud cover, even temporal means can be influenced by along-scanline artefacts if the observations are not balanced and effects cannot be cancelled out mutually. These effects can arise from a multitude of results which are not easily separated, if at all. Among the sources of artefacts, there are some sensor-specific calibration issues which should lead to similar responses in all processors, as well as processor-specific features which correspond with the individual choices in the algorithms. A set of methods is proposed and applied to MERIS data over two regions of interest in the North Atlantic and the South Pacific Gyre. The normalised water leaving reflectance products of four atmospheric correction processors, which have also been evaluated in match-up analysis, is analysed in order to find and interpret systematic effects across track. These results are summed up with a semi-objective ranking and are used as a complement to the match-up analysis in the decision for the best Atmospheric Correction (AC) processor. Although the need for discussion remains concerning the absolutes by which to judge an AC processor, this example demonstrates

  6. Degradation of Cu(In, Ga)Se{sub 2} thin-film solar cells due to the ionization effect of low-energy electrons

    Energy Technology Data Exchange (ETDEWEB)

    Kawakita, Shirou, E-mail: kawakita.shirou@jaxa.jp [Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505 (Japan); Imaizumi, Mitsuru [Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505 (Japan); Ishizuka, Shogo; Shibata, Hajime; Niki, Shigeru [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Okuda, Shuichi [Osaka Prefecture University (OPU), Sakai, Osaka 599-8570 (Japan); Kusawake, Hiroaki [Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505 (Japan)

    2015-05-01

    Cu (In, Ga)Se{sub 2} (CIGS) solar cells were irradiated with 100 keV electrons to reveal the characteristics of created radiation defects. 100 keV electrons cannot produce any displacement defects in CIGS. Low-fluence electrons improve the electrical performance of the CIGS solar cells due to the change in the conductive type of donor to acceptor in a metastable defect, which is equivalent to the light-soaking effect. However, high fluence electrons cause the cell performance to decline. From analysis based on changes in carrier density and electroluminescence, defects causing the decline in performance include donor- and non-radiative types. In addition, red-on-bias experiments showed an increase in III{sub Cu} defects due to electron irradiation. Based on these results, the degradation in the electrical performance of the CIGS solar cells irradiated with high electron fluence would be attributable to a change in the conductive type of III{sub Cu} defects. - Highlights: • Cu(In,Ga)Se2 Solar cells were irradiated with 100 and 250 keV electrons at low temperature. • These electrons degraded the electrical performance of Cu(In,Ga)Se2 sola cells. • The electrons induced ⅢCu defects in Cu(In,Ga)Se2.

  7. A study of the dissociative recombination of CaO+ with electrons: Implications for Ca chemistry in the upper atmosphere

    Science.gov (United States)

    Bones, D. L.; Gerding, M.; Höffner, J.; Martín, Juan Carlos Gómez; Plane, J. M. C.

    2016-12-01

    The dissociative recombination of CaO+ ions with electrons has been studied in a flowing afterglow reactor. CaO+ was generated by the pulsed laser ablation of a Ca target, followed by entrainment in an Ar+ ion/electron plasma. A kinetic model describing the gas-phase chemistry and diffusion to the reactor walls was fitted to the experimental data, yielding a rate coefficient of (3.0 ± 1.0) × 10-7 cm3 molecule-1 s-1 at 295 K. This result has two atmospheric implications. First, the surprising observation that the Ca+/Fe+ ratio is 8 times larger than Ca/Fe between 90 and 100 km in the atmosphere can now be explained quantitatively by the known ion-molecule chemistry of these two metals. Second, the rate of neutralization of Ca+ ions in a descending sporadic E layer is fast enough to explain the often explosive growth of sporadic neutral Ca layers.

  8. Cladding of the carbon fiber on the steel base using electron beam in the air atmosphere

    Science.gov (United States)

    Losinskaya, A.; Lozhkina, E.; Bardin, A.; Stepanova, N.

    2016-11-01

    The formation of the high-carbon layers on the low-carbon steel (0.18 % C) using the method of electron-beam partial melting of the carbon fibers is considered. A 1.4 MeV electron beam extracted into air was used. The features of the cladded layers formation using different binders for a reliable fixation of the cladding material are studied. It is revealed that the best results are obtained using the phenol-formaldehyde glue as the binder. A 3 mm thickness layers with 2.2 % C are shown to be formed.

  9. Atmospheric Pressure Plasma Jet as a Dry Alternative to Inkjet Printing in Flexible Electronics

    Science.gov (United States)

    Gandhiraman, Ram Prasad; Lopez, Arlene; Koehne, Jessica; Meyyappan, M.

    2016-01-01

    We have developed an atmospheric pressure plasma jet printing system that works at room temperature to 50 deg C unlike conventional aerosol assisted techniques which require a high temperature sintering step to obtain desired thin films. Multiple jets can be configured to increase throughput or to deposit multiple materials, and the jet(s) can be moved across large areas using a x-y stage. The plasma jet has been used to deposit carbon nanotubes, graphene, silver nanowires, copper nanoparticles and other materials on substrates such as paper, cotton, plastic and thin metal foils.

  10. Indoor atmospheric corrosion of electronic materials in tropical-mountain environments

    Energy Technology Data Exchange (ETDEWEB)

    Gil, H. [Corrosion and Protection Group, University of Antioquia, Street 62 No 52-59, Medellin (Colombia)], E-mail: harveth@gmail.com; Calderon, J.A. [Corrosion and Protection Group, University of Antioquia, Street 62 No 52-59, Medellin (Colombia)], E-mail: jacalder@udea.edu.co; Buitrago, C.P.; Echavarria, A.; Echeverria, F. [Corrosion and Protection Group, University of Antioquia, Street 62 No 52-59, Medellin (Colombia)

    2010-02-15

    Indoor corrosion rate during one year exposure for carbon steel, copper, nickel, and tin was determined in three different atmospheres in Colombia. In addition, pollutants deposition rates and environmental parameters were also measured during indoor-outdoor conditions. The results show higher pollutant deposition in outdoor conditions, while inside metallic boxes the pollutant deposition significantly diminishes. No difference for relative humidity values was found between inside and outside measurements. For all samples, except nickel, the corrosion rate decrease with exposure time. The nature of corrosion products was found to be related to the exposure conditions.

  11. Atmospheric heating due to black carbon aerosol during the summer monsoon period over Ballia: A rural environment over Indo-Gangetic Plain

    Science.gov (United States)

    Tiwari, S.; Dumka, U. C.; Hopke, P. K.; Tunved, P.; Srivastava, A. K.; Bisht, D. S.; Chakrabarty, R. K.

    2016-09-01

    Black carbon (BC) aerosols are one of the most uncertain drivers of global climate change. The prevailing view is that BC mass concentrations are low in rural areas where industrialization and vehicular emissions are at a minimum. As part of a national research program called the "Ganga Basin Ground Based Experiment-2014 under the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) Phase-III" of Ministry of Earth Sciences, Government of India, the continuous measurements of BC and particulate matter (PM) mass concentrations, were conducted in a rural environment in the highly-polluted Indo-Gangetic Plain region during 16th June to 15th August (monsoon period), 2014. The mean mass concentration of BC was 4.03 (± 0.85) μg m- 3 with a daily variability between 2.4 and 5.64 μg m- 3, however, the mean mass PM concentrations [near ultrafine (PM1.0), fine (PM2.5) and inhalable (PM10)] were 29.1(± 16.2), 34.7 (± 19.9) and 43.7 (± 28.3) μg m- 3, respectively. The contribution of BC in PM1.0 was approximately 13%, which is one of the highest being recorded. Diurnally, the BC mass concentrations were highest (mean: 5.89 μg m- 3) between 20:00 to 22:00 local time (LT) due to the burning of biofuels/biomass such as wood, dung, straw and crop residue mixed with dung by the local residents for cooking purposes. The atmospheric direct radiative forcing values due to the composite and BC aerosols were determined to be + 78.3, + 44.9, and + 45.0 W m- 2 and + 42.2, + 35.4 and + 34.3 W m- 2 during the months of June, July and August, respectively. The corresponding atmospheric heating rates (AHR) for composite and BC aerosols were 2.21, 1.26 and 1.26; and 1.19, 0.99 and 0.96 K day- 1 for the month of June, July and August, respectively, with a mean of 1.57 and 1.05 K day- 1 which was 33% lower AHR (BC) than for the composite particles during the study period. This high AHR underscores the importance of absorbing aerosols such as BC contributed by

  12. 27.3-day and Average 13.6-day Periodic Oscillations in the Earth's Rotation Rate and Atmospheric Pressure Fields Due to Celestial Gravitation Forcing

    Institute of Scientific and Technical Information of China (English)

    LI Guoqing; ZONG Haifeng; ZHANG Qingyun

    2011-01-01

    Variation in length of day of the Earth (LOD equivalent to the Earth's rotation rate) versus change in atmospheric geopotential height fields and astronomical parameters were analyzed for the years 1962-2006.This revealed that there is a 27.3-day and an average 13.6-day periodic oscillation in LOD and atmospheric pressure fields following lunar revolution around the Earth. Accompanying the alternating change in celestial gravitation forcing on the Earth and its atmosphere, the Earth's LOD changes from minimum to maximum,then to minimum. and the atmospheric geopotential height fields in the tropics oscillate from low to high,then to low. The 27.3-day and average 13.6-day periodic atmospheric oscillation in the tropics is proposed to be a type of strong atmospheric tide, excited by celestial gravitation forcing. A formula for a Tidal Index was derived to estimate the strength of the celestial gravitation forcing, and a high degree of correlation was found between the Tidal Index determined by astronomical parameters, LOD, and atmospheric geopotential height. The reason for the atmospheric tide is periodic departure of the lunar orbit from the celestial equator during lunar revolution around the Earth. The alternating asymmetric change in celestial gravitation forcing on the Earth and its atmosphere produces a "modulation" to the change in the Earth's LOD and atmospheric pressure fields.

  13. Electronic ground state OH(X) radical in a low-temperature atmospheric pressure plasma jet

    Science.gov (United States)

    Fuh, Che A.; Clark, Shane M.; Wu, Wei; Wang, Chuji

    2016-10-01

    The wide applicability of atmospheric pressure plasma jets in biomedicine stems from the presence of reactive nitrogen and oxygen species generated in these plasma jets. Knowing the absolute concentration of these reactive species is of utmost importance as it is critical, along with the particle flux obtained from the plasma feed gas flow rate to ensure that the correct dosage is applied during applications. In this study, we investigate and report the ground state OH(X) number density acquired using cavity ringdown spectroscopy, along the propagation axis (z-axis) of a cold atmospheric pressure helium plasma plume. The jet was generated by a repetitively pulsed mono-polar square wave of duration 1 μs running at a frequency of 9.9 kHz. The voltage supplied was 6.5 kV with the helium flow rate fixed at 3.6 standard liters per minute. The rotational and vibrational temperatures are simulated from the second positive system of nitrogen, N 2(C3πu-B3πg) , with the rotational temperature being spatially constant at 300 K along the propagation axis of the atmospheric pressure plasma jet while the vibrational temperature is 3620 K at the beginning of the plume and is observed to decrease downstream. The OH(A) emission intensity obtained via optical emission spectroscopy was observed to decrease downstream of the plasma jet. The OH(X) number density along the propagation axis was initially 2.2 × 1013 molecules cm-3 before increasing to a peak value of 2.4 × 1013 molecules cm-3, from which the number density was observed to decrease to 2.2 × 1013 molecules cm-3 downstream of the plasma jet. The total OH(A, X) in the plasma jet remained relatively constant along the propagation axis of the plasma jet before falling off at the tip of the jet. The increase in vibrational temperature downstream and the simultaneous measurements of both the excited state OH(A) and the ground state OH(X) reported in this study provide insights into the formation and consumption of this

  14. Perturbations to the Spatial and Temporal Characteristics of the Diurnally-Varying Atmospheric Boundary Layer Due to an Extensive Wind Farm

    Science.gov (United States)

    Sharma, V.; Parlange, M. B.; Calaf, M.

    2017-02-01

    The effect of extensive terrestrial wind farms on the spatio-temporal structure of the diurnally-evolving atmospheric boundary layer is explored. High-resolution large-eddy simulations of a realistic diurnal cycle with an embedded wind farm are performed. Simulations are forced by a constant geostrophic velocity with time-varying surface boundary conditions derived from a selected period of the CASES-99 field campaign. Through analysis of the bulk statistics of the flow as a function of height and time, it is shown that extensive wind farms shift the inertial oscillations and the associated nocturnal low-level jet vertically upwards by approximately 200 m; cause a three times stronger stratification between the surface and the rotor-disk region, and as a consequence, delay the formation and growth of the convective boundary layer (CBL) by approximately 2 h. These perturbations are shown to have a direct impact on the potential power output of an extensive wind farm with the displacement of the low-level jet causing lower power output during the night as compared to the day. The low-power regime at night is shown to persist for almost 2 h beyond the morning transition due to the reduced growth of the CBL. It is shown that the wind farm induces a deeper entrainment region with greater entrainment fluxes. Finally, it is found that the diurnally-averaged effective roughness length for wind farms is much lower than the reference value computed theoretically for neutral conditions.

  15. Perturbations to the Spatial and Temporal Characteristics of the Diurnally-Varying Atmospheric Boundary Layer Due to an Extensive Wind Farm

    Science.gov (United States)

    Sharma, V.; Parlange, M. B.; Calaf, M.

    2016-08-01

    The effect of extensive terrestrial wind farms on the spatio-temporal structure of the diurnally-evolving atmospheric boundary layer is explored. High-resolution large-eddy simulations of a realistic diurnal cycle with an embedded wind farm are performed. Simulations are forced by a constant geostrophic velocity with time-varying surface boundary conditions derived from a selected period of the CASES-99 field campaign. Through analysis of the bulk statistics of the flow as a function of height and time, it is shown that extensive wind farms shift the inertial oscillations and the associated nocturnal low-level jet vertically upwards by approximately 200 m; cause a three times stronger stratification between the surface and the rotor-disk region, and as a consequence, delay the formation and growth of the convective boundary layer (CBL) by approximately 2 h. These perturbations are shown to have a direct impact on the potential power output of an extensive wind farm with the displacement of the low-level jet causing lower power output during the night as compared to the day. The low-power regime at night is shown to persist for almost 2 h beyond the morning transition due to the reduced growth of the CBL. It is shown that the wind farm induces a deeper entrainment region with greater entrainment fluxes. Finally, it is found that the diurnally-averaged effective roughness length for wind farms is much lower than the reference value computed theoretically for neutral conditions.

  16. Nighttime D-region electron density measurements from ELF-VLF tweek radio atmospherics recorded at low latitudes

    Science.gov (United States)

    Maurya, A. K.; Veenadhari, B.; Singh, R.; Kumar, S.; Cohen, M.

    2012-12-01

    Dispersive atmospherics (tweeks) observed during 2010 simultaneously at two low latitude stations, Allahabad (geomagnetic lat., 16.79° N) and Nainital (geomagnetic lat. 20.48° N), have been utilized to estimate the nighttime D-region electron density at the ionospheric reflection height under the local nighttime propagation (21:00 - 02:00 LT or 15:30 - 20:30 UT). The analysis of simultaneously recorded tweeks at both the stations on five international quiet days during one month each from summer (June), winter (January) and equinox (March) seasons shows that the D-region electron density varies 21.5-24.5 cm-3 over the ionospheric reflection height of 85-95 km. The average values of Wait lower ionospheric parameters: ionospheric reference height h‧ and sharpness factor β are almost same during winter (86.1-85.9 km, 0.51-0.52 km-1) and equinox (85.6-85.7 km, 0.54 km-1) seasons. The values of h‧ and β during summer season are about 83.5 km and 0.60 km-1 at both stations. Overall, equivalent electron density profile obtained using tweek method shows lower values of electron density by about 5-60% than those obtained using IRI-2007 model and lower/higher by 2-68% than those obtained using rocket technique. The electron density estimated using all three techniques (tweek, IRI 2007, Rocket) is consistent in the altitude range of 82-98 km. The estimated geographic locations of causative lightnings of tweeks were matched with the locations and times of lightnings detected by the World-Wide Lightning Location Network (WWLLN). The WWLLN detected about 27.5% of causative lightnings of tweeks simultaneously observed at both the stations.

  17. Electron dynamics and plasma jet formation in a helium atmospheric pressure dielectric barrier discharge jet

    Energy Technology Data Exchange (ETDEWEB)

    Algwari, Q. Th. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); Electronic Department, College of Electronics Engineering, Mosul University, Mosul 41002 (Iraq); O' Connell, D. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom)

    2011-09-19

    The excitation dynamics within the main plasma production region and the plasma jets of a kHz atmospheric pressure dielectric barrier discharge (DBD) jet operated in helium was investigated. Within the dielectric tube, the plasma ignites as a streamer-type discharge. Plasma jets are emitted from both the powered and grounded electrode end; their dynamics are compared and contrasted. Ignition of these jets are quite different; the jet emitted from the powered electrode is ignited with a slight time delay to plasma ignition inside the dielectric tube, while breakdown of the jet at the grounded electrode end is from charging of the dielectric and is therefore dependent on plasma production and transport within the dielectric tube. Present streamer theories can explain these dynamics.

  18. Electron attachment to oxygen in nitrogen buffer gas at atmospheric pressure

    Science.gov (United States)

    Kučera, Marek; Stano, Michal; Wnorowska, Jolanta; Barszczewska, Wiesława; Loffhagen, Detlef; Matejčík, Štefan

    2013-11-01

    We have carried out experimental and theoretical studies of three body electron attachment (TBEA) to O2 in N2/O2 mixtures. We have applied three different experimental methods to determine the apparent rate constant k for TBEA to O2 for reduced electric fields E/ n from 0.5 Td up to 4.5 Td and O2 concentrations from 0.02% up to 3%. From the apparent rate constant k we have evaluated three body rate constant for electron attachment to O2 in pure O2 and in pure N2 . The comparison of present data with former studies shows that the former values of overestimated the efficiency of this reaction, while in case of we have found agreement with earlier studies. We have solved numerically the Boltzmann equation of the electrons and calculated the values of k, and using well established cross sections. Using the known collision cross section set for TBEA to O2, very good agreement between calculated and measured results for was found, while in the case of k and we had to introduce a scaling function, which describes the decrease of the efficiency of TBEA to O2 in presence of N2 and the dependence of the scaling function on E/ n was determined.

  19. Non-Maxwellian electron distributions in models of the solar atmosphere

    Science.gov (United States)

    Macneice, P.; Fontenla, J.; Ljepojevic, N. N.

    1991-01-01

    In this paper, the solar models of Fontenla et al. (1990) are extended to coronal temperatures using optically thin radiative losses and a semicircular loop geometry. The effects of a non-Maxwellian high-energy tail of the electron distribution function is tested by performing a Fokker-Planck calculation of the tail. The results show that the downward conductive heat flux is very clsoe to that given by Braginskii (1965) for small departures from a Maxwellian distribution. The effects of the high-energy tail of the electron distribution on element ionization are computed and found to be negligible for all ionization states of O, Ne, and Si. It is concluded that, for quiet sun loop models in stationary energy balance, the ionization state of all elements is not significantly affected by the non-Maxwellian tail of the electron velocity distribution, and that the heat flux can be computed by considering only small first-order departures from the Maxwellian distribution.

  20. Atmospheric Neutrinos

    Directory of Open Access Journals (Sweden)

    Takaaki Kajita

    2012-01-01

    Full Text Available Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron-neutrinos and muon-neutrinos are produced mainly by the decay chain of charged pions to muons to electrons. Atmospheric neutrino experiments observed zenith angle and energy-dependent deficit of muon-neutrino events. It was found that neutrino oscillations between muon-neutrinos and tau-neutrinos explain these data well. This paper discusses atmospheric neutrino experiments and the neutrino oscillation studies with these neutrinos.

  1. Increased electric sail thrust through removal of trapped shielding electrons by orbit chaotisation due to spacecraft body

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2009-08-01

    Full Text Available An electric solar wind sail is a recently introduced propellantless space propulsion method whose technical development has also started. The electric sail consists of a set of long, thin, centrifugally stretched and conducting tethers which are charged positively and kept in a high positive potential of order 20 kV by an onboard electron gun. The positively charged tethers deflect solar wind protons, thus tapping momentum from the solar wind stream and producing thrust. The amount of obtained propulsive thrust depends on how many electrons are trapped by the potential structures of the tethers, because the trapped electrons tend to shield the charged tether and reduce its effect on the solar wind. Here we present physical arguments and test particle calculations indicating that in a realistic three-dimensional electric sail spacecraft there exist a natural mechanism which tends to remove the trapped electrons by chaotising their orbits and causing them to eventually collide with the conducting tethers. We present calculations which indicate that if these mechanisms were able to remove trapped electrons nearly completely, the electric sail performance could be about five times higher than previously estimated, about 500 nN/m, corresponding to 1 N thrust for a baseline construction with 2000 km total tether length.

  2. Giant photoinduced Faraday rotation due to the spin-polarized electron gas in an n-GaAs microcavity

    Science.gov (United States)

    Giri, R.; Cronenberger, S.; Vladimirova, M.; Scalbert, D.; Kavokin, K. V.; Glazov, M. M.; Nawrocki, M.; Lemaître, A.; Bloch, J.

    2012-05-01

    Faraday rotation up to 19∘ in the absence of an external magnetic field is demonstrated in an n-type bulk GaAs microcavity under circularly polarized optical excitation. This strong effect is achieved because (i) the spin-polarized electron gas is an efficient Faraday rotator and (ii) the light wave makes multiple round trips in the cavity. We introduce a concept of Faraday rotation cross section as a proportionality coefficient between the rotation angle, electron spin density and optical path and calculate this cross section for our system. From independent measurements of photoinduced Faraday rotation and electron spin polarization we obtain quantitatively the cross section of the Faraday rotation induced by free electron spin polarization σFexp=-(2.5±0.6)×10-15 rad×cm2 for photon energy 18 meV below the band gap of GaAs, and electron concentration 2×1016 cm-3. It appears to exceed the theoretical value σFth=-0.7×10-15 rad×cm2, calculated without fitting parameters. We also demonstrate the proof-of-principle of a fast optically controlled Faraday rotator.

  3. Degradation of spatial resolution in thin-foil x-ray microchemical analysis due to plural scattering of electrons

    Energy Technology Data Exchange (ETDEWEB)

    Twigg, Mark Erickson

    1982-01-01

    A computer-based Monte Carlo simulation of incoherent plural scattering of electrons has been developed in order to estimate the broadening of an electron probe as it propagates through a solid. By applying this approach to modeling the spreading of a fine (50 A) probe focused on a thin foil in a scanning transmission electron microscope (STEM), we have estimated the spatial resolution of the compositional analysis obtainable using energy dispersive x-ray spectroscopy (EDS). Specifically, an attempt has been made to determine how the apparent microchemistry of a feature of finer dimensions than the broadened beam differs from the actual composition of the given feature. The apparent Ge concentration profile in the vicinity of a 200 A wide Ge platelet in a 5000 A thick Al foil was measured, using STEM and EDS, and compared with the profile predicted by Monte Carlo calculations. Results are presented and discussed.

  4. Comparison of macroscopic and microscopic (stereomicroscopy and scanning electron microscopy) features of bone lesions due to hatchet hacking trauma.

    Science.gov (United States)

    Nogueira, Luísa; Quatrehomme, Gérald; Bertrand, Marie-France; Rallon, Christophe; Ceinos, Romain; du Jardin, Philippe; Adalian, Pascal; Alunni, Véronique

    2017-03-01

    This experimental study examined the lesions produced by a hatchet on human bones (tibiae). A total of 30 lesions were produced and examined macroscopically (naked eye) and by stereomicroscopy. 13 of them were also analyzed using scanning electron microscopy. The general shape of the lesion, both edges, both walls, the kerf floor and the extremities were described. The length and maximum width of the lesions were also recorded. The microscopic analysis of the lesions led to the description of a sharp-blunt mechanism. Specific criteria were identified (lateral pushing back, fragmentation of the upraising, fossa dug laterally to the edge and vertical striae) enabling the forensic expert to conclude that a hacking instrument was used. These criteria are easily identifiable using scanning electron microscopy, but can also be observed with stereomicroscopy. Overall, lateral pushing back and vertical striae visible using stereomicroscopy and scanning electron microscopy signal the use of a hacking tool.

  5. Non-adiabatic electron behaviour due to short-scale electric field structures at collisionless shock waves

    Directory of Open Access Journals (Sweden)

    V. See

    2013-04-01

    Full Text Available Under sufficiently high electric field gradients, electron behaviour within exactly perpendicular shocks is unstable to the so-called trajectory instability. We extend previous work paying special attention to short-scale, high-amplitude structures as observed within the electric field profile. Via test particle simulations, we show that such structures can cause the electron distribution to heat in a manner that violates conservation of the first adiabatic invariant. This is the case even if the overall shock width is larger than the upstream electron gyroradius. The spatial distance over which these structures occur therefore constitutes a new scale length relevant to the shock heating problem. Furthermore, we find that the spatial location of the short-scale structure is important in determining the total effect of non-adiabatic behaviour – a result that has not been previously noted.

  6. PSI showed higher tolerance to Sb(V) than PSII due to stimulation of cyclic electron flow around PSI.

    Science.gov (United States)

    Wang, Shuzhi; Pan, Xiangliang; Zhang, Daoyong

    2015-01-01

    The knowledge of the effects of Sb(V) on the physiological characteristics of cyanobacteria was still limited. In the present study, responses of photosystem I and II (PSI and PSII), cyclic electron flow (CEF), and interphotosystem electron transport of Microcystis aeruginosa to 5-100 mg/l Sb(V) were synchronously measured using the Dual-PAM-100. 5 mg/l Sb (V) significantly inhibited PSII activity, but had no significant effects on PSI activity. At higher concentrations of Sb(V), the quantum yield and electron transport of PSI were less affected compared to PSII. The ratio of Y(II)/Y(I) significantly decreased with increasing Sb(V) concentration. It decreased from 0.7 for control to 0.4 for 100 mg/l Sb(V)-treated cells, indicating that the change of the distribution of quantum yields between two photosystems and more serious inhibition of PSII under stress of Sb(V) compared to PSI. CEF was activated associated with the inhibition of linear electron flow after exposure to Sb(V). The contribution of Y(CEF) to the quantum yield and activity of PSI increased with increasing Sb(V) concentrations. The cyclic electron transport rate made a significant contribution to electron transport rate of PSI, especially at high Sb(V) concentration (100 mg/l) and high illumination (above 555 μmol photons/m(2)/s). The stimulation of CEF was essential for the higher tolerance of PSI than PSII to Sb(V).

  7. Characterization of Atmospheric Aerosol Particles from a Mining City in Southwest China Using Electron Probe microanalysis

    Science.gov (United States)

    Cheng, X.; Huang, Y.; Lu, H., III; Liu, Z., IV; Wang, N. V.

    2015-12-01

    Xin Cheng1, Yi Huang1*, Huilin Lu2, Zaidong Liu2, Ningming Wang21 Key Laboratory of Geological Nuclear Technology of Sichuan Province, College of Earth Science, Chengdu University of Technology, Chengdu 610059, China. ; E-mail:chengxin_cdut@163.com 2 College of Earth Science, Chengdu University of Technology, Chengdu 610059, China. ; *Corresponding author: E-mail: huangyi@cdut.cn Panzhihua is a mining city located at Pan-Xi Rift valley, southwest China. It has a long industrial history of vanadium-titanium magnetite mining, iron and steel smelting, and coal-fired power plants. Atomospheric environment has been seriously contaminated with airborne paticles, which is threatening human health.The harmful effects of aerosols are dependent on certain characteristics such as microphysical properties. However, few studsies have been carried out on morphological information contained on single atmospheric particles in this area. In this study, we provide a detailed morphologically and chemically characterization of airborne particles collected at Panzhihua city in October, 2014, using a quantitative single particle analysis based on EPXMA. The results indicate that based on their chemical composition, five major types of particles were identified. Among these, aluminosilicate particles have typical spherical shapes and are produced during the high-temperature combustion; Fe-containing particles contains high level of Mn, and more likely originated from mineralogical and steel industry; Si-containing particles can originate from mineralogical source; V-Ti-Mn-containing particles are also produced by steel industry; Ca-containing particles,these particles are CaCO3, mainly from the mining of limestone mine. The results help us on tracing and partitioning different sources of atomospheric particles in the industrial area. Fig.1 Fe-rich shperical particles

  8. Verification of electron doping in single-layer graphene due to H{sub 2} exposure with thermoelectric power

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Ju; Kang, Hojin; Soler-Delgado, David; Kim, Kyung Ho; Park, Yung Woo, E-mail: ywpark@phya.snu.ac.kr, E-mail: kbh37@incheon.ac.kr [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Park, Min [Department of Nano Science and Technology, Seoul National University, Seoul 151-747 (Korea, Republic of); Lee, Minwoo; Jeong, Dae Hong [Department of Chemistry Education, Seoul National University, Seoul 151-742 (Korea, Republic of); Shin, Dong Seok; Kim, Byung Hoon, E-mail: ywpark@phya.snu.ac.kr, E-mail: kbh37@incheon.ac.kr [Department of Physics, Incheon National University, Incheon 406-772 (Korea, Republic of); Kubatkin, Sergey [Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Göteborg (Sweden)

    2015-04-06

    We report the electron doping of single-layer graphene (SLG) grown by chemical vapor deposition (CVD) by means of dissociative hydrogen adsorption. The transfer characteristic showed n-type doping behavior similar to that of mechanically exfoliated graphene. Furthermore, we studied the thermoelectric power (TEP) of CVD-grown SLG before and after exposure to high-pressure H{sub 2} molecules. From the TEP results, which indicate the intrinsic electrical properties, we observed that the CVD-grown SLG is n-type doped without degradation of the quality after hydrogen adsorption. Finally, the electron doping was also verified by Raman spectroscopy.

  9. Electron beam dynamics and self-cooling up to PeV level due to betatron radiation in plasma-based accelerators

    Science.gov (United States)

    Deng, Aihua; Nakajima, Kazuhisa; Liu, Jiansheng; Shen, Baifei; Zhang, Xiaomei; Yu, Yahong; Li, Wentao; Li, Ruxin; Xu, Zhizhan

    2012-08-01

    In plasma-based accelerators, electrons are accelerated by ultrahigh gradient of 1-100GV/m and undergo the focusing force with the same order as the accelerating force. Heated electrons are injected in a plasma wake and exhibit the betatron oscillation that generates synchrotron radiation. Intense betatron radiation from laser-plasma accelerators is attractive x-ray/gamma-ray sources, while it produces radiation loss and significant effects on energy spread and transverse emittance via the radiation reaction force. In this article, electron beam dynamics on transverse emittance and energy spread with considering radiation reaction effects are studied numerically. It is found that the emittance growth and the energy spread damping initially dominate and balance with radiative damping due to the betatron radiation. Afterward the emittance turns to decrease at a constant rate and leads to the equilibrium at a nanometer radian level with growth due to Coulomb scattering at PeV-level energies. A constant radiation loss rate RT=2/3 is found without regard to the electron beam and plasma conditions. Self-cooling of electron beams due to betatron radiation may guarantee TeV-range linear colliders and give hints on astrophysical ultrahigh-energy phenomena.

  10. Acceleration of plasma electrons by intense nonrelativistic ion and electron beams propagating in background plasma due to two-stream instability

    Science.gov (United States)

    Kaganovich, Igor D.

    2015-11-01

    In this paper we study the effects of the two-stream instability on the propagation of intense nonrelativistic ion and electron beams in background plasma. Development of the two-stream instability between the beam ions and plasma electrons leads to beam breakup, a slowing down of the beam particles, acceleration of the plasma particles, and transfer of the beam energy to the plasma particles and wave excitations. Making use of the particle-in-cell codes EDIPIC and LSP, and analytic theory we have simulated the effects of the two-stream instability on beam propagation over a wide range of beam and plasma parameters. Because of the two-stream instability the plasma electrons can be accelerated to velocities as high as twice the beam velocity. The resulting return current of the accelerated electrons may completely change the structure of the beam self - magnetic field, thereby changing its effect on the beam from focusing to defocusing. Therefore, previous theories of beam self-electromagnetic fields that did not take into account the effects of the two-stream instability must be significantly modified. This effect can be observed on the National Drift Compression Experiment-II (NDCX-II) facility by measuring the spot size of the extracted beamlet propagating through several meters of plasma. Particle-in-cell, fluid simulations, and analytical theory also reveal the rich complexity of beam- plasma interaction phenomena: intermittency and multiple regimes of the two-stream instability in dc discharges; band structure of the growth rate of the two-stream instability of an electron beam propagating in a bounded plasma and repeated acceleration of electrons in a finite system. In collaboration with E. Tokluoglu, D. Sydorenko, E. A. Startsev, J. Carlsson, and R. C. Davidson. Research supported by the U.S. Department of Energy.

  11. The first UV absorption band for indole is not due to two simultaneous orthogonal electronic transitions differing in dipole moment.

    Science.gov (United States)

    Catalán, Javier

    2015-05-21

    The currently accepted model for the photophysics of indole assumes that the first UV absorption band encompasses two orthogonal electronic transitions ((1)Lb and (1)La), leading to two electronic states with a markedly different dipole moment. However, there is a body of evidence not explained by this model, which led us to develop a new photophysical model for indole. Based on the new model, the polarity of the electronic ground state (S0) in indoles is very similar to that of the first electronic excited state (S1) producing this structured emission; however, this excited state can lead to a highly dipolar excited state (S1') with largely structureless emission under the influence of the polarity of the medium, and also, very likely, of its viscosity. The molecular structure of the new excited state can be reversibly converted into the normal structure of the compound. Previous observations were confirmed by the absorption, emission, and excitation spectra for indole, as well as by its polarized emission and excitation spectra in various media. Thus, the polarized emission spectra for indole in glycerol at 283 K and 223 K showed the transition dipole moments for the emission from the first two excited states in a polar medium, S1 and S1', to differ by less than 20°.

  12. Comparative study of the Martian suprathermal electron depletions based on Mars Global Surveyor, Mars Express, and Mars Atmosphere and Volatile EvolutioN mission observations

    Science.gov (United States)

    Steckiewicz, M.; Garnier, P.; André, N.; Mitchell, D. L.; Andersson, L.; Penou, E.; Beth, A.; Fedorov, A.; Sauvaud, J.-A.; Mazelle, C.; Brain, D. A.; Espley, J. R.; McFadden, J.; Halekas, J. S.; Larson, D. E.; Lillis, R. J.; Luhmann, J. G.; Soobiah, Y.; Jakosky, B. M.

    2017-01-01

    Nightside suprathermal electron depletions have been observed at Mars by three spacecraft to date: Mars Global Surveyor, Mars Express, and the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. This spatial and temporal diversity of measurements allows us to propose here a comprehensive view of the Martian electron depletions through the first multispacecraft study of the phenomenon. We have analyzed data recorded by the three spacecraft from 1999 to 2015 in order to better understand the distribution of the electron depletions and their creation mechanisms. Three simple criteria adapted to each mission have been implemented to identify more than 134,500 electron depletions observed between 125 and 900 km altitude. The geographical distribution maps of the electron depletions detected by the three spacecraft confirm the strong link existing between electron depletions and crustal magnetic field at altitudes greater than 170 km. At these altitudes, the distribution of electron depletions is strongly different in the two hemispheres, with a far greater chance to observe an electron depletion in the Southern Hemisphere, where the strongest crustal magnetic sources are located. However, the unique MAVEN observations reveal that below a transition region near 160-170 km altitude the distribution of electron depletions is the same in both hemispheres, with no particular dependence on crustal magnetic fields. This result supports the suggestion made by previous studies that these low-altitudes events are produced through electron absorption by atmospheric CO2.

  13. Reorganization of a large marine ecosystem due to atmospheric and anthropogenic pressure: a discontinuous regime shift in the Central Baltic Sea

    DEFF Research Database (Denmark)

    Moellmann, C; Diekmann, Rabea; Muller-Karulis, B

    2009-01-01

    Marine ecosystems such as the Baltic Sea are currently under strong atmospheric and anthropogenic pressure. Besides natural and human-induced changes in climate, major anthropogenic drivers such as overfishing and anthropogenic eutrophication are significantly affecting ecosystem structure...

  14. Non-Maxwellian electron distribution functions due to self-generated turbulence in collisionless guide-field reconnection

    OpenAIRE

    Muñoz, P. A.; J. Büchner

    2016-01-01

    Non-Maxwellian electron velocity space distribution functions (EVDF) are useful signatures of plasma conditions and non-local consequences of collisionless magnetic reconnection. In the past, EVDFs were obtained mainly for antiparallel reconnection and under the influence of weak guide-fields in the direction perpendicular to the reconnection plane. EVDFs are, however, not well known, yet, for oblique (or component-) reconnection in dependence on stronger guide-magnetic fields and for the exh...

  15. [Effects of nitrogen application and elevated atmospheric CO2 on electron transport and energy partitioning in flag leaf photosynthesis of wheat].

    Science.gov (United States)

    Zhang, Xu-cheng; Yu, Xian-feng; Ma, Yi-fan

    2011-03-01

    Wheat (Triticum aestivum) plants were pot-cultured in open top chambers at the nitrogen application rate of 0 and 200 mg x kg(-1) soil and the atmospheric CO2 concentration of 400 and 760 micromol x mol(-1). Through the determination of flag leaf nitrogen and chlorophyll contents, photosynthetic rate (Pn)-intercellar CO2 concentration (Ci) response curve, and chlorophyll fluorescence parameters at heading stage, the photosynthetic electron transport rate and others were calculated, aimed to investigate the effects of nitrogen application and elevated atmospheric CO2 concentration on the photosynthetic energy partitioning in wheat flag leaves. Elevated atmospheric CO2 concentration decreased the leaf nitrogen and chlorophyll contents, compared with the ambient one, and the chlorophyll a/b ratio increased at the nitrogen application rate of 200 mg x kg(-1). With the application of nitrogen, no evident variations were observed in the maximal photochemical efficiency (Fv/Fm), maximal quantum yield under irradiance (Fv'/Fm') of PS II reaction center, photochemical fluorescence quenching coefficient (q(p)), and actual PS II efficiency under irradiance (phi(PS II) at elevated atmospheric CO2 concentration, and the total photosynthetic electron transport rate (J(F)) of PS II reaction center had no evident increase, though the non-photochemical fluorescence quenching coefficient (NPQ) decreased significantly. With no nitrogen application, the Fv'/Fm', psi(PS II), and NPQ at elevated atmospheric CO2 concentration decreased significantly, and the J(F) had a significant decrease though the Fv/Fm and q(p) did not vary remarkably. Nitrogen application increased the J(F) and photochemical electron transport rate (Jc); while elevated atmospheric CO2 concentration decreased the photorespiration electron transport rate (J0), Rubisco oxidation rate (V0), ratio of photorespiration to photochemical electron transport rate (J0/Jc) , and Rubisco oxidation/carboxylation rate (Vo/Vc), but

  16. Plasma-Sheath Instability in Hall Thrusters Due to Periodic Modulation of the Energy of Secondary Electrons in Cyclotron Motion

    Energy Technology Data Exchange (ETDEWEB)

    Sydorenko, D.; Smolyakov, A.; Kaganovich, I.; Raitses, Y.

    2008-04-23

    Particle-in-cell simulation of Hall thruster plasmas reveals a plasma-sheath instability manifesting itself as a rearrangement of the plasma sheath near the thruster channel walls accompanied by a sudden change of many discharge parameters. The instability develops when the sheath current as a function of the sheath voltage is in the negative conductivity regime. The major part of the sheath current is produced by beams of secondary electrons counter-streaming between the walls. The negative conductivity is the result of nonlinear dependence of beam-induced secondary electron emission on the plasma potential. The intensity of such emission is defined by the beam energy. The energy of the beam in crossed axial electric and radial magnetic fields is a quasi-periodical function of the phase of cyclotron rotation, which depends on the radial profile of the potential and the thruster channel width. There is a discrete set of stability intervals determined by the final phase of the cyclotron rotation of secondary electrons. As a result, a small variation of the thruster channel width may result in abrupt changes of plasma parameters if the plasma state jumps from one stability interval to another.

  17. An assessment of the Photon Contamination due to Bremsstrahlung Radiation in the Electron Beams of a NEPTUN 10PC Linac using a Monte Carlo Method

    Directory of Open Access Journals (Sweden)

    Nasrollah Jabbari

    2009-03-01

    Full Text Available Introduction: In clinical electron beams, most of bremsstrahlung radiation is produced by various linac head structures. This bremsstrahlung radiation dose is influenced by the geometry and construction of every component of the linac treatment head structures. Thus, it can be expected that the amount of the contaminated photon dose due to bremsstrahlung radiation varies among different linacs, even for the same electron beam energy. The aims of this study were to simulate the NEPTUN 10PC linac electron beams and to calculate the photon contamination dose due to bremsstrahlung radiation in these beams using a Monte Carlo method. Materials and methods: A NEPTUN 10PC linac was simulated in its electron mode using the BEAMnrc code. This linac can provide three electron beam energies of 6, 8 and 10 MeV. Detailed information required for the simulation, including the geometry and materials of various components of the linac treatment head, was provided by the vender. For all simulations, the cut-off energies for electron and photon transport were set at ECUT=0.521 MeV and PCUT=0.010 MeV, respectively. The KS statistical test was used for validation of the simulated models. Then, relevant bremsstrahlung radiation doses for the three electron beam energies of the linac were calculated for the reference field using the Monte Carlo method.   Results: The KS test showed a good agreement between the calculated values (resulting from the simulations and the measured ones. The results showed that the amount of contaminated photon dose due to bremsstrahlung radiation from various components of the simulated linac at the surface of the phantom was between 0.2%-0.5% of the maximum dose for the three electron beam energies. Conclusion:  Considering the good agreement between the measured and simulated data, it can be concluded that the simulation method as well as the calculated bremsstrahlung doses have been made at a good level of accuracy and precision

  18. Climate response due to carbonaceous aerosols and aerosol-induced SST effects in NCAR community atmospheric model CAM3.5

    Directory of Open Access Journals (Sweden)

    W.-C. Hsieh

    2013-03-01

    Full Text Available This study used Community Atmospheric Model 3.5 (CAM3.5 to investigate the effects of carbonaceous aerosols on climate. The simulations include control runs with carbonaceous aerosols and no carbon runs in which carbonaceous aerosols were removed. The Slab Ocean Model (SOM and the fixed Sea Surface Temperature (SST were used to examine effects of ocean boundary conditions. Throughout this study, climate response induced by aerosol forcing was mainly analyzed in the following three terms: (1 aerosol radiative effects under fixed SST, (2 effects of aerosol-induced SST feedbacks , and (3 total effects including effects of aerosol forcing and SST feedbacks. The change of SST induced by aerosols has large impacts on distribution of climate response, the magnitudes in response patterns such as temperature, precipitation, zonal winds, mean meridional circulation, radiative fluxes and cloud coverage are different between the SOM and fixed SST runs. Moreover, different spatial responses between the SOM and fixed SST runs can also be seen in some local areas. This implies the importance of SST feedbacks on simulated climate response. The aerosol dimming effects cause a cooling predicted at low layers near the surface in most of carbonaceous aerosol source regions. The temperature response shows a warming (cooling predicted in the north (south high latitudes, suggesting that aerosol forcing can cause climate change in regions far away from its origins. Our simulation results show that warming of the troposphere due to black carbon decreases rainfall in the tropics. This implies that black carbon has possibly strong influence on weakening of the tropical circulation. Most of these changes in precipitation are negatively correlated with changes of radiative fluxes at the top of model. The changes in radiative fluxes at top of model are physically consistent with the response patterns in cloud fields. On global average, low-level cloud coverage increases, mid

  19. Climate response due to carbonaceous aerosols and aerosol-induced SST effects in NCAR community atmospheric model CAM3.5

    Directory of Open Access Journals (Sweden)

    W.-C. Hsieh

    2013-08-01

    Full Text Available This study used the Community Atmospheric Model 3.5 (CAM3.5 to investigate the effects of carbonaceous aerosols on climate. The simulations include control runs with 3 times the mass of carbonaceous aerosols as compared to the model's default carbonaceous aerosol mass, as well as no-carbon runs in which carbonaceous aerosols were removed. The slab ocean model (SOM and the fixed sea surface temperature (SST were used to examine effects of ocean boundary conditions. Throughout this study, climate response induced by aerosol forcing was mainly analyzed in the following three terms: (1 aerosol radiative effects under fixed SST, (2 effects of aerosol-induced SST feedbacks, and (3 total effects including effects of aerosol forcing and SST feedbacks. The change of SST induced by aerosols has large impacts on distribution of climate response; the magnitudes in response patterns such as temperature, precipitation, zonal winds, mean meridional circulation, radiative fluxes, and cloud coverage are different between the SOM and fixed SST runs. Moreover, different spatial responses between the SOM and fixed SST runs can also be seen in some local areas. This implies the importance of SST feedbacks on simulated climate response. The aerosol dimming effects cause a cooling predicted at low layers near the surface in most carbonaceous aerosol source regions. The temperature response shows a warming (cooling predicted in the north (south high latitudes, suggesting that aerosol forcing can cause climate change in regions far away from its origins. Our simulation results show that direct and semidirect radiative forcing due to carbonaceous aerosols decreases rainfall in the tropics. This implies that carbonaceous aerosols have possibly strong influence on weakening of the tropical circulation. Most changes in precipitation are negatively correlated with changes of radiative fluxes at the top of model. The changes in radiative fluxes at top of model are physically

  20. Electron Beam Focusing and Spreading due to interactions With Copropagating Plasma Waves and Lasers: Explanation of Simulation Results

    Science.gov (United States)

    Bowman, A.; Williams, R. L.

    2016-10-01

    Numerical simulation results suggest that a low energy electron beam, injected perpendicularly across co-propagating plasma waves and laser beams, can be compressed to a line focus under certain conditions, but under different conditions can be spread out into two main lobes on which bunching patterns are impressed. We report several explanations for these observations, and also discuss the similarity of these results to other research results previously reported in the literature. The prospects for testing these results in a laboratory will be discussed, as well as the use of these phenomena as diagnostics. Supported by the Department of Energy.

  1. Photon absorption and photocurrent in solar cells below semiconductor bandgap due to electron photoemission from plasmonic nanoantennas

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Uskov, Alexander; Gritti, Claudia;

    2014-01-01

    We model the electron photoemission frommetal nanoparticles into a semiconductor in a Schottky diode with a conductive oxide electrode hosting the nanoparticles. We show that plasmonic effects in the nanoparticles lead to a substantial enhancement in photoemission compared with devices with conti....... Such structure can form the dais of the development of plasmonic photoemission enhanced solar cells....... with continuous metal films. Optimally designed metal nanoparticles can provide an effectivemechanismfor the photon absorption in the infrared range below the semiconductor bandgap, resulting in the generation of a photocurrent in addition to the photocurrent from band-to-band absorption in a semiconductor...

  2. Intercomparison of peroxy radical measurements obtained at atmospheric conditions by laser-induced fluorescence and electron spin resonance spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Hofzumahaus

    2009-03-01

    Full Text Available Measurements of hydroperoxy radical (HO2 and organic peroxy radical (RO2 concentrations were performed by two different techniques in the atmospheric simulation chamber SAPHIR in Jülich, Germany. The first technique was the well-established Matrix Isolation Electron Spin Resonance (MIESR, which provides absolute measurements with a time resolution of 30 min and high accuracy (10%, 2 σ. The other technique, ROxLIF, has been newly developed. It is based on the selective chemical conversion of ROx radicals (HO2 and RO2 to OH, which is detected with high sensitivity by laser-induced fluorescence (LIF. ROxLIF is calibrated by quantitative photolysis of water vapor at 185 nm and provides ambient measurements at a temporal resolution of 1 min and accuracy of 20% (2 σ. The measurements of HO2 and RO2 obtained by the two techniques were compared for two types of atmospheric simulation experiments. In one experiment, HO2 and CH3O2 radicals were produced by photooxidation of methane in air at tropospheric conditions. In the second experiment, HO2 and C2H5O2 were produced by ozonolysis of 1-butene in air at dark conditions. The radical concentrations were within the range of 16 to 100 pptv for HO2 and 12 to 45 pptv for RO2. Good agreement was found in the comparison of the ROxLIF and MIESR measurements within their combined experimental uncertainties. Linear regressions to the combined data set yield slopes of 1.02±0.13 (1 σ for RO2 and 0.98±0.08 (1 σ for HO2 without significant offsets. The results confirm the calibration of the ROxLIF instrument and demonstrate that it can be applied with good accuracy for measurements of atmospheric peroxy radical concentrations.

  3. Non-Maxwellian electron distribution functions due to self-generated turbulence in collisionless guide-field reconnection

    CERN Document Server

    Muñoz, P A

    2016-01-01

    Non-Maxwellian electron velocity space distribution functions (EVDF) are useful signatures of plasma conditions and non-local consequences of collisionless magnetic reconnection. In the past, the evolution of the EVDFs was investigated mainly for antiparallel or weak-guide-field reconnection. The shape of EVDFs is, however, not well known yet for oblique (or component-) reconnection in dependence on a finite guide magnetic field component perpendicular to the reconnection plane. In view of the multi-spacecraft mission MMS, we derive the non-Maxwellian features of EVDFs formed by collisionless magnetic reconnection starting from very weak ($b_g\\approx0$) up to very strong ($b_g=8$) guide-field strengths $b_g$, taking into account the feedback of the self-generated turbulence. For this sake, we carry out 2.5D fully-kinetic Particle-in-Cell (PiC) simulations using the ACRONYM code. We obtained anisotropic EVDFs and the distribution of electron beams propagating along the separatrices as well as in the exhaust re...

  4. Acceleration of relativistic electrons due to resonant interaction with oblique monochromatic whistler-mode waves generated in the ionosphere.

    Science.gov (United States)

    Kuzichev, Ilya; Shklyar, David

    2016-04-01

    One of the most challenging problems of the radiation belt studies is the problem of particles energization. Being related to the process of particle precipitation and posing a threat to scientific instruments on satellites, the problem of highly energetic particles in the radiation belts turns out to be very important. A lot of progress has been made in this field, but still some aspects of the energization process remain open. The main mechanism of particle energization in the radiation belts is the resonant interaction with different waves, mainly, in whistler frequency range. The problem of special interest is the resonant wave-particle interaction of the electrons of relativistic energies. Relativistic resonance condition provides some important features such as the so-called relativistic turning acceleration discovered by Omura et al. [1, 2]. This process appears to be a very efficient mechanism of acceleration in the case of interaction with the whistler-mode waves propagating along geomagnetic field lines. But some whistler-mode waves propagate obliquely to the magnetic field lines, and the efficiency of relativistic turning acceleration in this case is to be studied. In this report, we present the Hamiltonian theory of the resonant interaction of relativistic electrons with oblique monochromatic whistler-mode waves. We have shown that the presence of turning point requires a special treatment when one aims to derive the resonant Hamiltonian, and we have obtained two different resonant Hamiltonians: one to be applied far enough from the turning point, while another is valid in the vicinity of the turning point. We have performed numerical simulation of relativistic electron interaction with whistler-mode waves generated in the ionosphere by a monochromatic source. It could be, for example, a low-frequency transmitter. The wave-field distribution along unperturbed particle trajectory is calculated by means of geometrical optics. We show that the obliquity of

  5. Calvin cycle mutants of photoheterotrophic purple nonsulfur bacteria fail to grow due to an electron imbalance rather than toxic metabolite accumulation.

    Science.gov (United States)

    Gordon, Gina C; McKinlay, James B

    2014-03-01

    Purple nonsulfur bacteria grow photoheterotrophically by using light for energy and organic compounds for carbon and electrons. Disrupting the activity of the CO2-fixing Calvin cycle enzyme, ribulose 1,5-bisphosphate carboxylase (RubisCO), prevents photoheterotrophic growth unless an electron acceptor is provided or if cells can dispose of electrons as H2. Such observations led to the long-standing model wherein the Calvin cycle is necessary during photoheterotrophic growth to maintain a pool of oxidized electron carriers. This model was recently challenged with an alternative model wherein disrupting RubisCO activity prevents photoheterotrophic growth due to the accumulation of toxic ribulose-1,5-bisphosphate (RuBP) (D. Wang, Y. Zhang, E. L. Pohlmann, J. Li, and G. P. Roberts, J. Bacteriol. 193:3293-3303, 2011, http://dx.doi.org/10.1128/JB.00265-11). Here, we confirm that RuBP accumulation can impede the growth of Rhodospirillum rubrum (Rs. rubrum) and Rhodopseudomonas palustris (Rp. palustris) RubisCO-deficient (ΔRubisCO) mutants under conditions where electron carrier oxidation is coupled to H2 production. However, we also demonstrate that Rs. rubrum and Rp. palustris Calvin cycle phosphoribulokinase mutants that cannot produce RuBP cannot grow photoheterotrophically on succinate unless an electron acceptor is provided or H2 production is permitted. Thus, the Calvin cycle is still needed to oxidize electron carriers even in the absence of toxic RuBP. Surprisingly, Calvin cycle mutants of Rs. rubrum, but not of Rp. palustris, grew photoheterotrophically on malate without electron acceptors or H2 production. The mechanism by which Rs. rubrum grows under these conditions remains to be elucidated.

  6. 600-T Magnetic Fields due to Cold Electron Flow in a simple Cu-Coil irradiated by High Power Laser pulses

    CERN Document Server

    Zhu, Baojun; Yuan, Dawei; Li, Yanfei; Li, Fang; Liao, Guoqian; Zhao, Jiarui; Zhong, Jiayong; Xue, Feibiao; Wei, Huigang; Zhang, Kai; Han, Bo; Pei, Xiaoxing; Liu, Chang; Zhang, Zhe; Wang, Weimin; Zhu, Jianqiang; Zhao, Gang; Zhang, Jie

    2015-01-01

    A new simple mechanism due to cold electron flow to produce strong magnetic field is proposed. A 600-T strong magnetic field is generated in the free space at the laser intensity of 5.7x10^15 Wcm^-2. Theoretical analysis indicates that the magnetic field strength is proportional to laser intensity. Such a strong magnetic field offers a new experimental test bed to study laser-plasma physics, in particular, fast-ignition laser fusion research and laboratory astrophysics.

  7. Particle-in-Cell Simulation for the Control of Electron Energy Distribution of Dielectric Barrier Discharges at Atmospheric Pressure

    Science.gov (United States)

    Bae, Hyo Won; Yel Lee, Jung; Lee, Ho-Jun; Lee, Hae June

    2011-10-01

    Recently, atmospheric pressure plasmas attract lots of interests for the useful applications such as surface modification and bio-medical treatment. In this study, a particle-in-cell Monte Carlo collision (PIC-MCC) simulation was adopted to investigate the discharge characteristics of a planar micro dielectric barrier discharge (DBD) with a driving frequency from 1 MHz to 50 MHz and with a gap distance from 60 to 500 micrometers. The variation of control parameters such as the gap distance, the driving wave form, and the applied voltage results in the change in the electron energy distribution function (EEDF). Through the relation between the ionization mean free path and the gap size, a significant change of EEDFs is achievable with the decrease of gap distance. Therefore, it is possible to categorize the operation range of DBDs for its applications by controlling the interactions between plasmas and neutral gas for the generation of preferable radicals. This work was supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 20104010100670).

  8. Suprathermal electron energy spectrum and nonlocally affected plasma-wall interaction in helium/air micro-plasma at atmospheric pressure

    Science.gov (United States)

    Demidov, V. I.; Adams, S. F.; Miles, J. A.; Koepke, M. E.; Kurlyandskaya, I. P.

    2016-10-01

    Details of ground-state and excited-state neutral atoms and molecules in an atmospheric-pressure micro-discharge plasma may be obtained by plasma electron spectroscopy (PLES), based on a wall probe. The presence and transport of energetic (suprathermal) electrons, having a nonlocal origin, are responsible for electrostatic charging of the plasma boundary surfaces to potentials many times that associated with the ambient electron kinetic energy. The energy-flux distribution function is shown to be controllable for applications involving analysis of composition and processes taking place in a multiphase (plasma-gas-solid), chemically reactive, interaction region.

  9. Reduced coupling of oxidative phosphorylation in vivo precedes electron transport chain defects due to mild oxidative stress in mice.

    Directory of Open Access Journals (Sweden)

    Michael P Siegel

    Full Text Available Oxidative stress and mitochondrial function are at the core of many degenerative conditions. However, the interaction between oxidative stress and in vivo mitochondrial function is unclear. We used both pharmacological (2 week paraquat (PQ treatment of wild type mice and transgenic (mice lacking Cu, Zn-superoxide dismutase (SOD1(-/- models to test the effect of oxidative stress on in vivo mitochondrial function in skeletal muscle. Magnetic resonance and optical spectroscopy were used to measure mitochondrial ATP and oxygen fluxes and cell energetic state. In both models of oxidative stress, coupling of oxidative phosphorylation was significantly lower (lower P/O at rest in vivo in skeletal muscle and was dose-dependent in the PQ model. Despite this reduction in efficiency, in vivo mitochondrial phosphorylation capacity (ATPmax was maintained in both models, and ex vivo mitochondrial respiration in permeabilized muscle fibers was unchanged following PQ treatment. In association with the reduced P/O, PQ treatment led to a dose-dependent reduction in PCr/ATP ratio and increased phosphorylation of AMPK. These results indicate that oxidative stress uncouples oxidative phosphorylation in vivo and results in energetic stress in the absence of defects in the mitochondrial electron transport chain.

  10. Measurement of the energy loss of an electron bunch passing in a chicane-type bunch compressor due to the coherent synchrotron radiation

    CERN Document Server

    Okuda, S; Yokoyama, K

    2000-01-01

    The energy loss of an electron beam due to the coherent synchrotron radiation in the components for beam transportation possibly degrades the quality of the beam. In this work the energy loss of an intense single-bunch electron beam passing through a chicane-type bunch compressor has been investigated. The single-bunch beams are being used for self-amplified spontaneous emission experiments in Osaka University. At a beam energy of 27 MeV and the charge of electrons in a bunch of 22 nC the peak shift on the energy spectrum of the beam by 1% and the energy loss of about 0.5% have been observed. In order to evaluate the energy of the coherent synchrotron radiation emitted in the bunch compressor a form factor of the electron bunch has been assumed, according to the results for the measurements of the time profile of the electron bunch with a streak camera and the spectrum of the coherent transition radiation.

  11. Atmospheric Diffusion Loss of Radiation Belt Trapped Electrons Injected by High Altitude Nuclear Detonation%高空核爆炸注入辐射带电子的大气扩散损失

    Institute of Scientific and Technical Information of China (English)

    牛胜利; 罗旭东; 王建国; 乔登江

    2011-01-01

    With Fokerer-Plank equation of pitch-angle diffusion, a numerical method for atmospheric diffusion loss of radiation belt trapped electrons is shown. Flux and energy spectrum are calculated as atmospheric scattering of fission β spectrum electrons injected in radiation belt by high altitude nuclear detonation. Diffusion due to atmospheric scattering is remarkable as L < 1. 3. Low energy electrons are removed more rapidly than those with high energy. Electron flux decays rapidly at an initial phase and then decays gradually aa an exponential function of time.%利用辐射带电子大气倾角扩散的福克-普朗克方程,通过推导与拟合处理扩散系数表征式,构造二阶精度有限差分格式,给出辐射带捕获电子大气扩散损失的数值计算方法.计算高空核爆炸裂变β谱电子注入辐射带后在不同L壳上的通量损失和能谱变化,结果表明,当L<1.3时,大气作用引起的扩散损失效应明显,低能电子比高能电子消失要快,电子通量初始阶段衰减很快,随后逐渐近似成时间指数函数形式衰减.

  12. Evaporative deposition patterns of bacteria from a sessile drop: effect of changes in surface wettability due to exposure to a laboratory atmosphere.

    Science.gov (United States)

    Baughman, Kyle F; Maier, Raina M; Norris, Theresa A; Beam, Brooke M; Mudalige, Anoma; Pemberton, Jeanne E; Curry, Joan E

    2010-05-18

    Evaporative deposition from a sessile drop is a simple and appealing way to deposit materials on a surface. In this work, we deposit living, motile colloidal particles (bacteria) on mica from drops of aqueous solution. We show for the first time that it is possible to produce a continuous variation in the deposition pattern from ring deposits to cellular pattern deposits by incremental changes in surface wettability which we achieve by timed exposure of the mica surface to the atmosphere. We show that it is possible to change the contact angle of the drop from less than 5 degrees to near 20 degrees by choice of atmospheric exposure time. This controls the extent of drop spreading, which in turn determines the architecture of the deposition pattern.

  13. On the generation of electric field and infrared radiation in aerosol clouds due to radon emanation in the atmosphere before earthquakes

    Directory of Open Access Journals (Sweden)

    V. A. Liperovsky

    2008-10-01

    Full Text Available The non-stationary Frenkel model of the generator of spikes of the local electric field with time scales of 1–100 min in the atmosphere near seismic fracture regions some days before strong earthqukes is analysed. The model suggests an aerosol cloud, an increased ionisation velocity (e.g. by radon emanation, and an upward flow of air. It was found that during times of earthquake activity (that means a few days before an earthquake, for realistic increases of the ionization intensity of the atmosphere, mosaic-likely occurring and disappearing pulses of local electric fields with intensities of the order of 103−3×103 Vm−1 should be observable. These electric fields would also cause spikes of non-equilibrium IR emissions (0.7–20 μm and local spikes of the magnetic field. The authors propose to perform special complex Earth-based observations of the night-time emissions of the atmosphere in the IR region and of the magnetic as well as quasi-stationary electric fields at some points near to fracture regions in seismo-active belts.

  14. Electron heating enhancement due to plasma series resonance in a capacitively coupled RF discharge: Electrical modeling and comparison to experimental measurements

    Science.gov (United States)

    Cao, Minglu; Lu, Yijia; Cheng, Jia; Ji, Linhong

    2016-09-01

    The electron heating enhancement due to the self-excitation of the plasma series resonance in capacitively coupled plasmas is revisited by a combination of an equivalent circuit model and experiments. To improve the model accuracy, measured voltage waveforms at the powered electrode are used instead of prescribing a sinusoidal voltage supply in series with a bias capacitance. The results calculated from the electrical model are consistent with the experimental measurements performed by a Langmuir probe with verification of a microwave interferometer, at pressures of 0.2 and 0.3 Torr. High harmonics occurring in the discharge currents agree with observations in previous research. The nonlinear plasma series resonance effect is found to have a notable contribution to both ohmic and stochastic heating evaluated by the electron heating efficiencies.

  15. Changes in microstructural parameters of NB4D2 silk fibres due to electron irradiation: X-ray line profile analysis

    Indian Academy of Sciences (India)

    Sangappa; S Asha; P Parameswara; R Somashekar

    2011-12-01

    The present study is concerned with changes of microcrystalline parameters in NB4D2 (Bombyx mori) silk fibres, due to electron irradiation. The irradiation process was performed in air at room temperature using 8 MeV electron beam at different dose rates: 0, 25, 50 and 75 kGy, respectively. X-ray recording of these irradiated samples and the line profile analysis were carried out. The crystal imperfection parameters such as crystallite size $\\langle N \\rangle$, lattice strain (g in %) and surface weighted crystallite size ($D_{s}$) were computed and compared with other physical parameters in order to asertain the changes that have crept into these irradiated fibres. Exponential, lognormal and Reinhold functions for the column length distributions have been used for the determination of these parameters.

  16. Acidification due to microbial dechlorination near a trichloroethene DNAPL is overcome with pH buffer or formate as electron donor: experimental demonstration in diffusion-cells.

    Science.gov (United States)

    Philips, Jo; Maes, Nele; Springael, Dirk; Smolders, Erik

    2013-04-01

    Acidification due to microbial dechlorination of trichloroethene (TCE) can limit the bio-enhanced dissolution of TCE dense non-aqueous phase liquid (DNAPL). This study related the dissolution enhancement of a TCE DNAPL to the pH buffer capacity of the medium and the type of electron donor used. In batch systems, dechlorination was optimal at pH7.1-7.5, but was completely inhibited below pH6.2. In addition, dechlorination in batch systems led to a smaller pH decrease at an increasing pH buffer capacity or with the use of formate instead of lactate as electron donor. Subsequently, bio-enhanced TCE DNAPL dissolution was quantified in diffusion-cells with a 5.5 cm central sand layer, separating a TCE DNAPL layer from an aqueous top layer. Three different pH buffer capacities (2.9 mM-17.9 mM MOPS) and lactate or formate as electron donor were applied. In the lactate fed diffusion-cells, the DNAPL dissolution enhancement factor increased from 1.5 to 2.2 with an increase of the pH buffer capacity. In contrast, in the formate fed diffusion-cells, the DNAPL dissolution enhancement factor (2.4±0.3) was unaffected by the pH buffer capacity. Measurement of the pore water pH confirmed that the pH decreased less with an increased pH buffer capacity or with formate instead of lactate as electron donor. These results suggest that the significant impact of acidification on bio-enhanced DNAPL dissolution can be overcome by the amendment of a pH buffer or by applying a non acidifying electron donor like formate.

  17. Integration of measurements with atmospheric dispersion models: Source term estimation for dispersal of (239)Pu due to non-nuclear detonation of high explosive

    Science.gov (United States)

    Edwards, L. L.; Harvey, T. F.; Freis, R. P.; Pitovranov, S. E.; Chernokozhin, E. V.

    1992-10-01

    The accuracy associated with assessing the environmental consequences of an accidental release of radioactivity is highly dependent on our knowledge of the source term characteristics and, in the case when the radioactivity is condensed on particles, the particle size distribution, all of which are generally poorly known. This paper reports on the development of a numerical technique that integrates the radiological measurements with atmospheric dispersion modeling. This results in a more accurate particle-size distribution and particle injection height estimation when compared with measurements of high explosive dispersal of (239)Pu. The estimation model is based on a non-linear least squares regression scheme coupled with the ARAC three-dimensional atmospheric dispersion models. The viability of the approach is evaluated by estimation of ADPIC model input parameters such as the ADPIC particle size mean aerodynamic diameter, the geometric standard deviation, and largest size. Additionally we estimate an optimal 'coupling coefficient' between the particles and an explosive cloud rise model. The experimental data are taken from the Clean Slate 1 field experiment conducted during 1963 at the Tonopah Test Range in Nevada. The regression technique optimizes the agreement between the measured and model predicted concentrations of (239)Pu by varying the model input parameters within their respective ranges of uncertainties. The technique generally estimated the measured concentrations within a factor of 1.5, with the worst estimate being within a factor of 5, very good in view of the complexity of the concentration measurements, the uncertainties associated with the meteorological data, and the limitations of the models. The best fit also suggest a smaller mean diameter and a smaller geometric standard deviation on the particle size as well as a slightly weaker particle to cloud coupling than previously reported.

  18. Transient simulation and analysis of current collapse due to trapping effects in AlGaN/GaN high-electron-mobility transistor

    Institute of Scientific and Technical Information of China (English)

    周幸叶; 冯志红; 王元刚; 顾国栋; 宋旭波; 蔡树军

    2015-01-01

    In this paper, two-dimensional (2D) transient simulations of an AlGaN/GaN high-electron-mobility transistor (HEMT) are carried out and analyzed to investigate the current collapse due to trapping effects. The coupling effect of the trapping and thermal effects are taken into account in our simulation. The turn-on pulse gate-lag transient responses with different quiescent biases are obtained, and the pulsed current–voltage (I–V ) curves are extracted from the transients. The experi-mental results of both gate-lag transient current and pulsed I–V curves are reproduced by the simulation, and the current collapse due to the trapping effect is explained from the view of physics based on the simulation results. In addition, the results show that bulk acceptor traps can influence the gate-lag transient characteristics of AlGaN/GaN HEMTs besides surface traps and that the thermal effect can accelerate the emission of captured electrons for traps. Pulse transient simu-lation is meaningful in analyzing the mechanism of dynamic current collapse, and the work in this paper will benefit the reliability study and model development of GaN-based devices.

  19. ON THE POSSIBILITY OF SIGNIFICANT ELECTRON DEPLETION DUE TO NANOGRAIN CHARGING IN THE COMA OF COMET 67P/CHURYUMOV-GERASIMENKO NEAR PERIHELION

    Energy Technology Data Exchange (ETDEWEB)

    Vigren, E.; Eriksson, A. I.; Wahlund, J.-E. [Swedish Institute of Space physics, Uppsala (Sweden); Galand, M. [Department of Physics, Imperial College London, London (United Kingdom); Lavvas, P., E-mail: erik.vigren@irfu.se [Groupe de Spectrométrie Moléculaire et Atmosphérique, Université Reims Champagne-Ardenne, UMR 7331, F-51687 Reims (France)

    2015-01-10

    We approach the complicated phenomena of gas-dust interactions in a cometary ionosphere, focusing in particular on the possibility of significant depletion in electron number density due to grain charging. Our one-dimensional ionospheric model, accounting for grain charging processes, is applied to the subsolar direction and the diamagnetic cavity of 67P/Churyuomov-Gerasimenko, the target comet for the ESA Rosetta mission, at perihelion (∼1.25-1.30 AU). We argue on the one hand that grains with radii >100 nm are unlikely to significantly affect the overall ionospheric particle balance within this environment, at least for cometocentric distances >10 km. On the other hand, if nanograins with radii in the 1-3 nm range are ejected to the coma at a level of ∼1% with respect to the mass of the sublimated gas, a significant electron depletion is expected up to cometocentric distances of several tens of kilometers. We relate these results to the recent Cassini discoveries of very pronounced electron depletion compared with the positive ion population in the plume of Enceladus, which has been attributed to nanograin charging.

  20. Integrating a MRI scanner with a 6 MV radiotherapy accelerator: dose increase at tissue-air interfaces in a lateral magnetic field due to returning electrons

    Energy Technology Data Exchange (ETDEWEB)

    Raaijmakers, A J E; Raaymakers, B W; Lagendijk, J J W [Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht (Netherlands)

    2005-04-07

    In the framework of the development of the integration of a MRI-scanner with a linear accelerator, the influence of a lateral, magnetic field on the dose distribution has to be determined. Dose increase is expected at tissue-air boundaries, due to the electron return effect (ERE): electrons entering air will describe a circular path and return into the phantom causing extra dose deposition. Using IMRT with many beam directions, this exit dose will not constitute a problem. Dose levels behind air cavities will decrease because of the absence of electrons crossing the cavity. The ERE has been demonstrated both by simulation and experiment. Monte Carlo simulations are performed with GEANT4, irradiating a water-air-water phantom in a lateral magnetic field. Also an air tube in water has been simulated, resulting in slightly twisted regions of dose increase and decrease. Experimental demonstration is achieved by film measurement in a perspex-air-perspex phantom in an electromagnet. Although the ERE causes dose increase before air cavities, relatively flat dose profiles can be obtained for the investigated cases using opposite beam configurations. More research will be necessary whether this holds for more realistic geometries with the use of IMRT and whether the ERE can be turned to our advantage when treating small tumour sites at air cavities.

  1. Physical and statistical modeling of attenuation due to atmospheric hydrometeors on free-space optical links at 850 and 1550 nm

    Science.gov (United States)

    Grabner, Martin; Kvicera, Vaclav

    2012-10-01

    Atmospheric hydrometeors such as rain and fog may cause attenuation of an optical signal and degrade the performance of free-space optical (FSO) systems. For efficient design of the FSO links, attenuation characteristics must be predicted by sufficiently reliable models that have been tested on experimental data. A long term experiment on the FSO links operating at 850 and 1550 nm wavelengths is conducted in Prague. The path lengths are 100 and 853 m. Received power fluctuations on the FSO links and relevant meteorological quantities such as rain intensity and liquid water content of fog are measured simultaneously. The relationships between the physical parameters of hydrometeors and path attenuation are analyzed and compared with theoretical relations derived using the Mie scattering theory together with some natural assumptions about the physical properties of scattering particles such as droplet size distribution of different types of hydrometeors. Long term statistics of attenuation are obtained and availability performance of the experimental FSO links is assessed. The method for predicting attenuation statistics based on physical and statistical models is introduced and the errors of the proposed models with respect to measured data are analyzed. The models are compared with the existing empirical relationships derived from other FSO experiments and differences are discussed.

  2. Production of extended plasma channels in atmospheric air by amplitude-modulated UV radiation of GARPUN-MTW Ti : sapphire—KrF laser. Part 2. Accumulation of plasma electrons and electric discharge control

    Science.gov (United States)

    Zvorykin, V. D.; Ionin, Andrei A.; Levchenko, A. O.; Mesyats, Gennadii A.; Seleznev, L. V.; Sinitsyn, D. V.; Smetanin, Igor V.; Sunchugasheva, E. S.; Ustinovskii, N. N.; Shutov, A. V.

    2013-04-01

    The problem of the production of extended (~1 m) plasma channels is studied in atmospheric air by amplitude-modulated laser pulses of UV radiation, which are a superposition of a subpicosecond USP train amplified in a regenerative KrF amplifier with an unstable confocal resonator and a quasi-stationary lasing pulse. The USPs possess a high (0.2-0.3 TW) peak power and efficiently ionise oxygen molecules due to multiphoton ionisation, and the quasi-stationary lasing pulse, which has a relatively long duration (~100 ns), maintains the electron density at a level ne = (3-5) × 1014 cm—3 by suppressing electron attachment to oxygen. Experiments in laser triggering of high-voltage electric discharges suggest that the use of combined pulses results in a significant lowering of the breakdown threshold and enables controlling the discharge trajectory with a higher efficiency in comparison with smooth pulses. It was shown that controlled breakdowns may develop with a delay of tens of microseconds relative to the laser pulse, which is many orders of magnitude greater than the lifetime of free electrons in the laser-induced plasma. We propose a mechanism for this breakdown, which involves speeding-up of the avalanche ionisation of the air by negative molecular oxygen ions with a low electron binding energy (~0.5 eV) and a long lifetime (~1 ms), which are produced upon cessation of the laser pulse.

  3. Emission of greenhouse gases in the atmosphere of the Manaus city due to burning of fossil fuels; Emissao de gases poluentes na atmosfera urbana da cidade de Manaus devida a queima de combustiveis fosseis

    Energy Technology Data Exchange (ETDEWEB)

    Valois, I.M. [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil). Fac. de Tecnologia], E-mail: ivalois@ufam.edu.br; Cartaxo, E.F. [Universidade Federal do Amazonas (NIEMA/UFAM), Manaus, AM (Brazil). Fac. de Tecnologia. Nucleo de Energia, Meio Ambiente e Agua], E-mail: ecartaxo@ufam.edu.br; Chaar, Jamal da Silva [Universidade Federal do Amazonas (ICE/UFAM), Manaus, AM (Brazil). Inst. de Ciencias Exatas

    2009-07-01

    This paper intends to think over the impacts of pollutants gases in the atmosphere of the city of Manaus, caused by the thermal, the main electricity source in the State of Amazonas. The focus of the study is the urban atmosphere where physical and chemical phenomenon accelerate the effects of increased concentration of some components and secondary pollutants, which are produced due to human activities. It is based on two studies: monitoring the exhaust gas applied at a factory in the district of Aparecida, located in the urban area, and monitoring conducted by the energy operating company, about the influence of exhaust gas around the district of Mauazinho, also in urban area. It is a preliminary research that seeks to demonstrate the inconsistency of some studies and the need to make progress in search for more efficient methods and techniques. This is an important step toward a policy of environmental management that will complement future studies about air pollution in the city. (author)

  4. Bad news about an old poison. A case of nicotine poisoning due to both ingestion and injection of the content of an electronic cigarette refill

    Directory of Open Access Journals (Sweden)

    Gianfranco Cervellin

    2013-10-01

    Full Text Available There are increasing concerns about the escalating use of electronic cigarettes (e-cigarettes. In particular, smokers have been advised by important agencies such as the US Food and Drug Administration about the potential harm to the health of these products, being now considered as drug delivery devices. The leading issues supporting this statement include the repeated inhalation of propylene glycol that is used as a diluent in refills, accidental poisoning, as well as evidence that ecigarettes may promote continued smoking since their use may compromise quitting motivations. Some authors have minimized these risks, considering the potential advantages of these devices for public health. Here we describe the first case of nicotine poisoning due to both ingestion and intravenous injection of the content of an e-cigarette refill, incorrectly mixed with methadone, bottled in a generic vial.

  5. Radiation exposure due to cosmic rays and solar X-ray photons at various atmospheric heights in aviation range over India

    Science.gov (United States)

    Palit, Sourav; Chakrabarti, Sandip Kumar; Bhattacharya, Arnab

    2016-07-01

    In this presentation we present our work on the continuous monitoring of radiation exposure in terms of effective dose rates, due to galactic cosmic rays (GCR) and solar X-rays at various altitudes within aviation range over India. As India belongs to equatorial region, there is negligible contribution from solar energetic particles (SEP). The calculation of cosmic ray counts as well as the solar X-ray photons are performed on the basis of the observation of various Dignity series balloon experiments on cosmic ray and solar high energy radiation studies, conducted by ICSP and Monte Carlo simulations performed with GEANT4 detector simulation software. The information on solar activity level from Geostationary Operational Environmental Satellite system (GOES) are employed in the calculations. A program, which is done entirely in MATLAB is employed to update regularly in a website, where we show images of dose rate (μSv) distribution over India at four different heights within the aviation range (updating at an interval of 30 minutes) and the approximate dose rates thats should be experienced by a pilot in an entire flight time between pairs of stations distributed all over India.

  6. Quantitative energy-dispersive electron probe X-ray microanalysis for single-particle analysis and its application for characterizing atmospheric aerosol particles

    Indian Academy of Sciences (India)

    Shila Maskey; Chul-Un Ro

    2011-02-01

    An energy-dispersive electron probe X-ray microanalysis (ED-EPMA) technique using an energy-dispersive X-ray detector with an ultra-thin window, designated as low-Z particle EPMA, has been developed. The low-Z particle EPMA allows the quantitative determination of concentrations of low-Z elements such as C, N and O, as well as higher-Z elements that can be analysed by conventional ED-EPMA. The quantitative determination of low-Z elements (using full Monte Carlo simulations, from the electron impact to the X-ray detection) in individual particles has improved the applicability of single-particle analysis, especially in atmospheric environmental aerosol research; many environmentally important atmospheric particles, e.g. sulphates, nitrates, ammonium and carbonaceous particles, contain low-Z elements. To demonstrate its practical applicability, the application of the low-Z particle EPMA for the characterization of Asian Dust, urban and subway aerosol particles is shown herein. In addition, it is demonstrated that the Monte Carlo calculation can also be applied in a quantitative single-particle analysis using transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectrometry (EDX), showing that the technique is useful and reliable for the characterization of submicron aerosol particles

  7. Theoretical simulation of the picosecond runaway-electron beam in coaxial diode filled with SF6 at atmospheric pressure

    Science.gov (United States)

    Kozyrev, Andrey; Kozhevnikov, Vasily; Lomaev, Mikhail; Sorokin, Dmitry; Semeniuk, Natalia; Tarasenko, Victor

    2016-05-01

    This paper presents detailed results of gas discharge theoretical simulation and the explanation of probabilistic mechanism of fast-electrons generation. Within the framework of a hybrid mathematical model, the hydrodynamic and the kinetic approaches are used simultaneously in order to describe the dynamics of different components of a low-temperature discharge plasma. The breakdown of a coaxial diode occurs in the form of a dense plasma region expanding from the cathode. On this background there is a formation of runaway electrons that are initiated by the ensemble of plasma electrons generated in the region of locally enhanced electric field within the front of the dense plasma. It is shown that the power spectrum of fast electrons in the discharge contains the group of electrons with the so-called “anomalous” energies. Comparison of the calculation results with the existent experimental data gives a good agreement for all major process parameters.

  8. Energetic particle precipitation in ECHAM5/MESSy1 – Part 1: Downward transport of upper atmospheric NOx produced by low energy electrons

    Directory of Open Access Journals (Sweden)

    C. Brühl

    2008-12-01

    Full Text Available The atmospheric chemistry general circulation model ECHAM5/MESSy1 has been extended by processes that parameterize particle precipitation. Several types of particle precipitation that directly affect NOy and HOx concentrations in the middle atmosphere are accounted for and discussed in a series of papers. In the companion paper, the ECHAM5/MESSy1 solar proton event parameterization is discussed, while in the current paper we focus on low energy electrons (LEE that produce NOx in the upper atmosphere. For the flux of LEE NOx into the top of the model domain a novel technique which can be applied to most atmospheric chemistry general circulation models has been developed and is presented here. The technique is particularly useful for models with an upper boundary between the stratopause and mesopause and therefore cannot directly incorporate upper atmospheric NOx production. The additional NOx source parametrization is based on a measure of geomagnetic activity, the Ap index, which has been shown to be a good proxy for LEE NOx interannual variations. HALOE measurements of LEE NOx that has been transported into the stratosphere are used to develop a scaling function which yields a flux of NOx that is applied to the model top. We describe the implementation of the parameterization as the submodel SPACENOX in ECHAM5/MESSy1 and discuss the results from test simulations. The NOx enhancements and associated effects on ozone are shown to be in good agreement with independent measurements. Ap index data is available for almost one century, thus the parameterization is suitable for simulations of the recent climate.

  9. Energetic particle precipitation in ECHAM5/MESSy1 – Part 1: Downward transport of upper atmospheric NOx produced by low energy electrons

    Directory of Open Access Journals (Sweden)

    C. Brühl

    2009-04-01

    Full Text Available The atmospheric chemistry general circulation model ECHAM5/MESSy1 has been extended by processes that parameterise particle precipitation. Several types of particle precipitation that directly affect NOy and HOx concentrations in the middle atmosphere are accounted for and discussed in a series of papers. In the companion paper, the ECHAM5/MESSy1 solar proton event parametrisation is discussed, while in the current paper we focus on low energy electrons (LEE that produce NOx in the upper atmosphere. For the flux of LEE NOx into the top of the model domain a novel technique which can be applied to most atmospheric chemistry general circulation models has been developed and is presented here. The technique is particularly useful for models with an upper boundary between the stratopause and mesopause and therefore cannot directly incorporate upper atmospheric NOx production. The additional NOx source parametrisation is based on a measure of geomagnetic activity, the Ap index, which has been shown to be a good proxy for LEE NOx interannual variations. HALOE measurements of LEE NOx that has been transported into the stratosphere are used to develop a scaling function which yields a flux of NOx that is applied to the model top. We describe the implementation of the parametrisation as the submodel SPACENOX in ECHAM5/MESSy1 and discuss the results from test simulations. The NOx enhancements are shown to be in good agreement with independent measurements. Ap index data is available for almost one century, thus the parametrisation is suitable for simulations of the recent climate.

  10. Welding of a corrosion-resistant composite material based on VT14 titanium alloy obtained using an electron beam emitted into the atmosphere

    Science.gov (United States)

    Golkovski, M. G.; Samoylenko, V. V.; Polyakov, I. A.; Lenivtseva, O. G.; Chakin, I. K.; Komarov, P. N.; Ruktuev, A. A.

    2017-01-01

    The study investigates the possibility of inert gas arc welding of a double layer composite material on a titanium base with an anti-corrosive layer obtained by fused deposition of a powder mix containing tantalum and niobium over a titanium base using an electron beam emitted into the atmosphere. Butt welding and fillet welding options were tested with two types of edge preparation. Welds were subjected to a metallographic examination including a structural study and an analysis of the chemical and phase composition of the welds. A conclusion was made regarding the possibility of using welding for manufacturing of items from the investigated composite material.

  11. Development of Miniaturized Difference Frequency Generation, Fiber Optic, and Quantum Cascade Laser Systems in Conjunction With Integrated Electronics for Global Studies of Atmospheric Tracers Using UAVs.

    Science.gov (United States)

    Witinski, M. F.; Lapson, L. B.; Anderson, J. G.

    2007-12-01

    In order to harness the power of UAVs (Unmanned Aerial Vehicles) for in situ atmospheric monitoring of tracers such as CO2, N2O, CH4, and H2O, we have developed small, lightweight, single mode laser systems with co- developed integrated electronics. The laser sources are of various types including newly developed cavity- enhanced difference frequency generation (CE DFG), distributed feedback quantum cascade lasers (DFB QCLs), and new types of commercially available DFB diode lasers. All are continuous wave (cw) and thermo-electrically cooled, ensuring a high instrument duty cycle in a compact, low maintenance package. The light sources are collimated with miniature aspherical lenses and coupled into a home-built astigmatic Herriott cell for detection of the various targets using direct absorption. In parallel with the optical components, we have developed integrated electrical systems for laser control, data processing, and acquisition. A prototype instrument suite is described that illustrates the importance of parallel development of optical and electrical components in achieving an apparatus that is compact, fully automated, and highly capable scientifically. Although the emphasis here is on atmospheric tracers, this technology could be applied to spectroscopic measurements of other atmospheric species such as isotopes, free radicals, and reactive intermediates.

  12. The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29

    Science.gov (United States)

    Kowalski, Adam F.; Allred, Joel C.; Daw, Adrian; Cauzzi, Gianna; Carlsson, Mats

    2017-02-01

    The 2014 March 29 X1 solar flare (SOL20140329T17:48) produced bright continuum emission in the far- and near-ultraviolet (NUV) and highly asymmetric chromospheric emission lines, providing long-sought constraints on the heating mechanisms of the lower atmosphere in solar flares. We analyze the continuum and emission line data from the Interface Region Imaging Spectrograph (IRIS) of the brightest flaring magnetic footpoints in this flare. We compare the NUV spectra of the brightest pixels to new radiative-hydrodynamic predictions calculated with the RADYN code using constraints on a nonthermal electron beam inferred from the collisional thick-target modeling of hard X-ray data from Reuven Ramaty High Energy Solar Spectroscopic Imager. We show that the atmospheric response to a high beam flux density satisfactorily achieves the observed continuum brightness in the NUV. The NUV continuum emission in this flare is consistent with hydrogen (Balmer) recombination radiation that originates from low optical depth in a dense chromospheric condensation and from the stationary beam-heated layers just below the condensation. A model producing two flaring regions (a condensation and stationary layers) in the lower atmosphere is also consistent with the asymmetric Fe ii chromospheric emission line profiles observed in the impulsive phase.

  13. Numerical studies of independent control of electron density and gas temperature via nonlinear coupling in dual-frequency atmospheric pressure dielectric barrier discharge plasmas

    Science.gov (United States)

    Zhang, Z. L.; Nie, Q. Y.; Wang, Z. B.; Gao, X. T.; Kong, F. R.; Sun, Y. F.; Jiang, B. H.

    2016-07-01

    Dielectric barrier discharges (DBDs) provide a promising technology of generating non-equilibrium cold plasmas in atmospheric pressure gases. For both application-focused and fundamental studies, it is important to explore the strategy and the mechanism for enabling effective independent tuning of key plasma parameters in a DBD system. In this paper, we report numerical studies of effects of dual-frequency excitation on atmospheric DBDs, and modulation as well as separate tuning mechanism, with emphasis on dual-frequency coupling to the key plasma parameters and discharge evolution. With an appropriately applied low frequency to the original high frequency, the numerical calculation demonstrates that a strong nonlinear coupling between two frequencies governs the process of ionization and energy deposition into plasma, and thus raises the electron density significantly (e.g., three times in this case) in comparisons with a single frequency driven DBD system. Nevertheless, the gas temperature, which is mainly determined by the high frequency discharge, barely changes. This method then enables a possible approach of controlling both averaged electron density and gas temperature independently.

  14. A Critical Review of Published Data on the Gas Temperature and the Electron Density in the Electrolyte Cathode Atmospheric Glow Discharges

    Directory of Open Access Journals (Sweden)

    Tamás Cserfalvi

    2012-05-01

    Full Text Available Electrolyte Cathode Discharge (ELCAD spectrometry, a novel sensitive multielement direct analytical method for metal traces in aqueous solutions, was introduced in 1993 as a new sensing principle. Since then several works have tried to develop an operational mechanism for this exotic atmospheric glow plasma technique, however these attempts cannot be combined into a valid model description. In this review we summarize the conceptual and technical problems we found in this upcoming research field of direct sensors. The TG gas temperature and the ne electron density values published up to now for ELCAD are very confusing. These data were evaluated by three conditions. The first is the gas composition of the ELCAD plasma, since TG was determined from the emitted intensity of the N2 and OH bands. Secondly, since the ELCAD is an atmospheric glow discharge, thus, the obtained TG has to be close to the Te electron temperature. This can be used for the mutual validation of the received temperature data. Thirdly, as a consequence of the second condition, the values of TG and ne have to agree with the Engel-Brown approximation of the Saha-equation related to weakly ionized glow discharge plasmas. Application of non-adequate experimental methods and theoretical treatment leads to unreliable descriptions which cannot be used to optimize the detector performance.

  15. Three-Dimensional X-ray Observation of Atmospheric Biological Samples by Linear-Array Scanning-Electron Generation X-ray Microscope System

    Science.gov (United States)

    Ogura, Toshihiko

    2011-01-01

    Recently, we developed a soft X-ray microscope called the scanning-electron generation X-ray microscope (SGXM), which consists of a simple X-ray detection system that detects X-rays emitted from the interaction between a scanning electron beam (EB) and the thin film of the sample mount. We present herein a three-dimensional (3D) X-ray detection system that is based on the SGXM technology and designed for studying atmospheric biological samples. This 3D X-ray detection system contains a linear X-ray photodiode (PD) array. The specimens are placed under a CuZn-coated Si3N4 thin film, which is attached to an atmospheric sample holder. Multiple tilt X-ray images of the samples are detected simultaneously by the linear array of X-ray PDs, and the 3D structure is calculated by a new 3D reconstruction method that uses a simulated-annealing algorithm. The resulting 3D models clearly reveal the inner structure of the bacterium. In addition, the proposed method can easily be used for diverse samples in a broad range of scientific fields. PMID:21731770

  16. Three-dimensional X-ray observation of atmospheric biological samples by linear-array scanning-electron generation X-ray microscope system.

    Science.gov (United States)

    Ogura, Toshihiko

    2011-01-01

    Recently, we developed a soft X-ray microscope called the scanning-electron generation X-ray microscope (SGXM), which consists of a simple X-ray detection system that detects X-rays emitted from the interaction between a scanning electron beam (EB) and the thin film of the sample mount. We present herein a three-dimensional (3D) X-ray detection system that is based on the SGXM technology and designed for studying atmospheric biological samples. This 3D X-ray detection system contains a linear X-ray photodiode (PD) array. The specimens are placed under a CuZn-coated Si₃N₄ thin film, which is attached to an atmospheric sample holder. Multiple tilt X-ray images of the samples are detected simultaneously by the linear array of X-ray PDs, and the 3D structure is calculated by a new 3D reconstruction method that uses a simulated-annealing algorithm. The resulting 3D models clearly reveal the inner structure of the bacterium. In addition, the proposed method can easily be used for diverse samples in a broad range of scientific fields.

  17. Three-dimensional X-ray observation of atmospheric biological samples by linear-array scanning-electron generation X-ray microscope system.

    Directory of Open Access Journals (Sweden)

    Toshihiko Ogura

    Full Text Available Recently, we developed a soft X-ray microscope called the scanning-electron generation X-ray microscope (SGXM, which consists of a simple X-ray detection system that detects X-rays emitted from the interaction between a scanning electron beam (EB and the thin film of the sample mount. We present herein a three-dimensional (3D X-ray detection system that is based on the SGXM technology and designed for studying atmospheric biological samples. This 3D X-ray detection system contains a linear X-ray photodiode (PD array. The specimens are placed under a CuZn-coated Si₃N₄ thin film, which is attached to an atmospheric sample holder. Multiple tilt X-ray images of the samples are detected simultaneously by the linear array of X-ray PDs, and the 3D structure is calculated by a new 3D reconstruction method that uses a simulated-annealing algorithm. The resulting 3D models clearly reveal the inner structure of the bacterium. In addition, the proposed method can easily be used for diverse samples in a broad range of scientific fields.

  18. Development of a sampling method for carbonyl compounds released due to the use of electronic cigarettes and quantitation of their conversion from liquid to aerosol.

    Science.gov (United States)

    Jo, Sang-Hee; Kim, Ki-Hyun

    2016-01-15

    In this study, an experimental method for the collection and analysis of carbonyl compounds (CCs) released due to the use of electronic cigarettes (e-cigarettes or ECs) was developed and validated through a series of laboratory experiments. As part of this work, the conversion of CCs from a refill solution (e-solution) to aerosol also was investigated based on mass change tracking (MCT) approach. Aerosol samples generated from an e-cigarette were collected manually using 2,4-dinitrophenylhydrazine (DNPH) cartridges at a constant sampling (puffing) velocity of 1 L min(-1) with the following puff conditions: puff duration (2s), interpuff interval (10s), and puff number (5, 10, and 15 times). The MCT approach allowed us to improve the sampling of CCs through critical evaluation of the puff conditions in relation to the consumed quantities of refill solution. The emission concentrations of CCs remained constant when e-cigarettes were sampled at or above 10 puff. Upon aerosolization, the concentrations of formaldehyde and acetaldehyde increased 6.23- and 58.4-fold, respectively, relative to their concentrations in e-solution. Furthermore, a number of CCs were found to be present in the aerosol samples which were not detected in the initial e-solution (e.g., acetone, butyraldehyde, and o-tolualdehyde).

  19. Threshold-Voltage Shifts in Organic Transistors Due to Self-Assembled Monolayers at the Dielectric: Evidence for Electronic Coupling and Dipolar Effects.

    Science.gov (United States)

    Aghamohammadi, Mahdieh; Rödel, Reinhold; Zschieschang, Ute; Ocal, Carmen; Boschker, Hans; Weitz, R Thomas; Barrena, Esther; Klauk, Hagen

    2015-10-21

    The mechanisms behind the threshold-voltage shift in organic transistors due to functionalizing of the gate dielectric with self-assembled monolayers (SAMs) are still under debate. We address the mechanisms by which SAMs determine the threshold voltage, by analyzing whether the threshold voltage depends on the gate-dielectric capacitance. We have investigated transistors based on five oxide thicknesses and two SAMs with rather diverse chemical properties, using the benchmark organic semiconductor dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene. Unlike several previous studies, we have found that the dependence of the threshold voltage on the gate-dielectric capacitance is completely different for the two SAMs. In transistors with an alkyl SAM, the threshold voltage does not depend on the gate-dielectric capacitance and is determined mainly by the dipolar character of the SAM, whereas in transistors with a fluoroalkyl SAM the threshold voltages exhibit a linear dependence on the inverse of the gate-dielectric capacitance. Kelvin probe force microscopy measurements indicate this behavior is attributed to an electronic coupling between the fluoroalkyl SAM and the organic semiconductor.

  20. Electron Density and Temperature Measurement by Stark Broadening in a Cold Argon Arc-Plasma Jet at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    ZHOU Qiuping; CHENG Cheng; MENG Yuedong

    2009-01-01

    Determination of both the electron density and temperature simultaneously in a cold argon arc-plasma jet by analyzing the Stark broadening of two different emission lines is presented.This method is based on the fact that the Stark broadening of different lines has a different dependence on the electron density and temperature.Therefore,a comparison of two or more line broadenings allows us to diagnose the electron density and temperature simultaneously.In this study we used the first two Balmer series hydrogen lines H_α and H_β for their large broadening width.For this purpose,a small amount of hydrogen was introduced into the discharge gas.The results of the Gigosos-Cardenoso computational model,considering more relevant processes for the hydrogen Balmer lines,is used to process the experimental data.With this method,we obtained reliable electron density and temperature,1.88 ×10 ~(15) cm~(-3 )and 13000 K,respectively.Possible sources of error were also analyzed.

  1. On the way of calculating the atmospheric environmental damage due to the pollution in the coal-mining resource cities%煤炭资源型城市大气环境污染损失核算研究

    Institute of Scientific and Technical Information of China (English)

    冯思静; 马云东; 刘辉; 潘日芳

    2012-01-01

    The present article is inclined to introduce an improved method for calculating the atmospheric environmental damage due to the pollution in the coal-mining resource cities by taking Fuxin city as our case study. As to the methods for calculating environmental values in the environmental economics, it is of great necessity to mention the functional relationship among the physical quantity of loss, the value quantity of loss due to the pollution the coal production brings about to the environment. In order to calculate the economic loss caused by the atmospheric environmental pollution, we have prepared an equation and calculation method by joining the environmental value evaluation methods, such as human capital approach and the market value law, the economic loss caused by the atmospheric environmental pollution derived from the coal exploitation of the city in terms of currency. In order to analyze and evaluate the actualities of the atmospheric environmental quality loss and existing problems generated from coal mining quantitatively and qualitatively, this article put forward the calculation method by accounting the physical quantity and value quantity respectively. Such calculation can provide reference to the construction of ecological compensation and ecological regionaliza-tion. The calculation result of ours shows: the atmospheric environ-mental pollution loss caused by coal exploitation in the city in 2010 was about 1.266 billion Yuan, amounting to 80.09 Yuan loss for per metric ton coal, in which the cost of human health is thought of 65.63 % of the total loss, which is regarded as the biggest loss. Since the regions involved and evaluated are difficult to conform with the natural ecological environment remands, the population scale and socioeconomic development situation when they are evaluated with the end-results checking method, the accounting results of this article can only be treated as a reference to the upper limit. The uncertainty of the

  2. Variation in mechanical behavior due to different build directions of Titanium6Aluminum4Vanadium fabricated by electron beam additive manufacturing technology

    Science.gov (United States)

    Roy, Lalit

    Titanium has always been a metal of great interest since its discovery especially for critical applications because of its excellent mechanical properties such as light weight (almost half of that of the steel), low density (4.4 gm/cc) and high strength (almost similar to steel). It creates a stable and adherent oxide layer on its surface upon exposure to air or water which gives it a great resistance to corrosion and has made it a great choice for structures in severe corrosive environment and sea water. Its non-allergic property has made it suitable for biomedical application for manufacturing implants. Having a very high melting temperature, it has a very good potential for high temperature applications. But high production and processing cost has limited its application. Ti6Al4V is the most used titanium alloy for which it has acquired the title as `workhouse' of the Ti family. Additive layer Manufacturing (ALM) has brought revolution in manufacturing industries. Today, this additive manufacturing has developed into several methods and formed a family. This method fabricates a product by adding layer after layer as per the geometry given as input into the system. Though the conception was developed to fabricate prototypes and making tools initially, but its highly economic aspect i.e., very little waste material for less machining and comparatively lower production lead time, obviation of machine tools have drawn attention for its further development towards mass production. Electron Beam Melting (EBM) is the latest addition to ALM family developed by Arcam, ABRTM located in Sweden. The electron beam that is used as heat source melts metal powder to form layers. For this thesis work, three different types of specimens have been fabricated using EBM system. These specimens differ in regard of direction of layer addition. Mechanical properties such as ultimate tensile strength, elastic modulus and yield strength, have been measured and compared with standard data

  3. Structure and properties of chromium-containing coatings produced by electron-beam facing in the atmosphere

    Science.gov (United States)

    Poletika, I. M.; Golkovskii, M. G.; Krylova, T. A.; Perovskaya, M. V.

    2009-03-01

    The chemical and phase compositions and the structure of layers formed by electron-beam facing of low-carbon steel with mixtures of powdered chromium and chromium carbide in air are studied. The microhardness of the layers is determined over their thickness. The faced steels are tested for bending strength, corrosion resistance, and resistance to abrasive wear. A possible mechanism of formation of the properties of the coating, i.e., the hardness, the wear resistance, and the crack resistance, is considered.

  4. Effect of electron irradiation and packaging atmosphere on the survival of Aeromonas hydrophila in minced poultry meat

    Energy Technology Data Exchange (ETDEWEB)

    Stecchini, M.L.; Sarais, I.; Del Torre, M. [Dipartimento di Scienze degli Alimenti, Udine (Italy); Fuochi, P.G. [Istituto FRAE-CNR, Bologna (Italy)

    1995-10-01

    Resistance to electron irradiation of Aeromonas hydrophila inoculated in minced poultry meat packed in presence of air or under vacuum was examined. Surviving bacteria were counted on starch ampicillin agar containing 100 {mu}g/ml of ampicillin. Radiation resistance, expressed as D{sub 10} values, was calculated from the survival curves and found to be 0.12 and 0.14 kGy in poultry meat packed in air or under vacuum respectively. Storage at 2{sup o}C of meat samples irradiated at 0.5 kGy further reduced the number of A. hydrophila. (Author).

  5. Effect of electron irradiation and packaging atmosphere on the survival of aeromonas hydrophila in minced poultry meat

    Science.gov (United States)

    Stecchini, M. L.; Sarais, I.; Del Torre, M.; Fuochi, P. G.

    1995-02-01

    Resistance to electron irradiation of Aeromonas hydrophila inoculated in minced poultry meat packed in presence of air or under vacuum was examined. Surviving bacteria were counted on starch ampicillin agar containing 100 μg/ml of ampicillin. Radiation resistance, expressed as D 10 values, was calculated from the survival curves and found to be 0.12 and 0.12 kGy in poultry meat packed in air or under vacuum respectively. Storage at 2°C of meat samples irradiated at 0.5 kGy further reduced the number of A. hydrophila.

  6. A study of the electron image due to ionizing events in a two-dimensional liquid argon TPC with a 24 cm drift gap

    Science.gov (United States)

    Bonetti, S.; Braggiotti, A.; Buckley, E.; Campanella, M.; Carugno, G.; Cecchet, G.; Cennini, P.; Centro, S.; Ciocio, A.; Cittolin, S.; Dainese, B.; Ferro-Luzzi, M.; Gasparini, F.; Gonidec, A.; Manfredi, P. F.; Meroni, E.; Muñoz, R.; Perreau, J.-M.; Pietropaolo, F.; Ptohos, F.; Ragusa, F.; Rossi, P.; Rubbia, C.; Schinzel, D.; Schmidt, W. F.; Seidl, W.

    1990-01-01

    We have tested a liquid argon time projection chamber with a novel wire configuration based on electrostatic focussing which allows the realization of a nondestructive detection of the electron image produced by ionizing events. The chamber was tested in a 5 GeV pion beam at the CERN proton synchrotron. The measured pulse shapes at both 200 V/cm and 500 V/cm were in very good agreement with the expected shapes, calculated taking into account the electron lifetime, the response of the electronics and the longitudinal diffusion of the electron cloud. The measured electron drift velocity was in good agreement with the results of other workers as well as with our previous measurements. We have also analysed a sample of events containing delta rays in order to study the behaviour of low-energy electrons in the liquid argon. We find that for electron energies greater than 5 MeV the measured energy spectrum agrees very well with the predicted spectrum after corrections for acceptance and energy loss, hence demonstrating the feasibility of recognizing low-energy electrons in liquid argon.

  7. The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares I: Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29

    CERN Document Server

    Kowalski, Adam F; Daw, Adrian N; Cauzzi, Gianna; Carlsson, Mats

    2016-01-01

    The 2014 March 29 X1 solar flare (SOL20140329T17:48) produced bright continuum emission in the far- and near-ultraviolet (NUV) and highly asymmetric chromospheric emission lines, providing long-sought constraints on the heating mechanisms of the lower atmosphere in solar flares. We analyze the continuum and emission line data from the Interface Region Imaging Spectrograph (IRIS) of the brightest flaring magnetic footpoints in this flare. We compare the NUV spectra of the brightest pixels to new radiative-hydrodynamic predictions calculated with the RADYN code using constraints on a nonthermal electron beam inferred from the collisional thick-target modeling of hard X-ray data from RHESSI. We show that the atmospheric response to a high beam flux density satisfactorily achieves the observed continuum brightness in the NUV. The NUV continuum emission in this flare is consistent with hydrogen (Balmer) recombination radiation that originates from low optical depth in a dense chromospheric condensation and from th...

  8. Ab initio quantum-chemical computations of the electronic states in HgBr2 and IBr: Molecules of interest on the Earth's atmosphere

    Science.gov (United States)

    Sitkiewicz, Sebastian P.; Oliva, Josep M.; Dávalos, Juan Z.; Notario, Rafael; Saiz-Lopez, Alfonso; Alcoba, Diego R.; Oña, Ofelia B.; Roca-Sanjuán, Daniel

    2016-12-01

    The electronic states of atmospheric relevant molecules IBr and HgBr2 are reported, within the UV-Vis spectrum range (170 nm ≤λp h o t o n≤600 nm) by means of the complete-active-space self-consistent field/multi-state complete-active-space second-order perturbation theory/spin-orbit restricted-active-space state-interaction (CASSCF/MS-CASPT2/SO-RASSI) quantum-chemical approach and atomic-natural-orbital relativistic-correlation-consistent (ANO-RCC) basis sets. Several analyses of the methodology were carried out in order to reach converged results and therefore to establish a highly accurate level of theory. Good agreement is found with the experimental data with errors not higher than around 0.1 eV. The presented analyses shall allow upcoming studies aimed to accurately determine the absorption cross sections of interhalogen molecules and compounds with Hg that are relevant to better comprehend the photochemical processes taking place in the atmosphere.

  9. Electron spectroscopic analysis of the human lipid skin barrier: cold atmospheric plasma-induced changes in lipid composition.

    Science.gov (United States)

    Marschewski, Marcel; Hirschberg, Joanna; Omairi, Tarek; Höfft, Oliver; Viöl, Wolfgang; Emmert, Steffen; Maus-Friedrichs, Wolfgang

    2012-12-01

    The lipids of the stratum corneum comprise the most important components of the skin barrier. In patients with ichthyoses or atopic dermatitis, the composition of the skin barrier lipids is disturbed resulting in dry, scaly, itching erythematous skin. Using the latest X-Ray Photoelectron Spectroscopy (XPS) technology, we investigated the physiological skin lipid composition of human skin and the effects of cold atmospheric plasma treatment on the lipid composition. Skin lipids were stripped off forearms of six healthy volunteers using the cyanoacrylate glue technique, plasma treated or not and then subjected to detailed XPS analysis. We found that the human lipid skin barrier consisted of 84.4% carbon (+1.3 SEM%), 10.8% oxygen (+1.0 SEM%) and 4.8% nitrogen (+0.3 SEM%). The composition of physiological skin lipids was not different in males and females. Plasma treatment resulted in significant changes in skin barrier lipid stoichiometry. The total carbon amount was reduced to 76.7%, and the oxygen amount increased to 16.5%. There was also a slight increase in nitrogen to 6.8%. These changes could be attributed to reduced C-C bonds and increased C-O, C=O, C-N and N-C-O bonds. The moderate increase in nitrogen was caused by an increase in C-N and N-C-O bonds. Our results show for the first time that plasma treatment leads to considerable changes in the human skin lipid barrier. Our proof of principle investigations established the technical means to analyse, if plasma-induced skin lipid barrier changes may be beneficial in the treatment of ichthyotic or eczematous skin.

  10. The p-H symmetry breaking in dissociative ionization of H2 due to the molecular ion interaction with the ejected electron

    CERN Document Server

    Serov, Vladislav V

    2014-01-01

    We propose a novel mechanism of electron localization and molecular symmetry breaking in dissociative photoionization of the \\H molecule. The Coulomb field of the ejected electron can induce transition of the remaining H$_2^+$ ion from the gerade $^2\\Sigma_g^1(1s\\sigma_g)$ to the ungerade $^2\\Sigma_u^1(2p\\sigma_u)$ electronic state when the nuclei in a bound vibrational state are near the outer turning point. The superposition of this process with a direct transition to vibrational continuum should produce a non-gerade ionic state which results in observed asymmetry in the $p$-H ejection relative to the electron ejection direction at a small kinetic energy release.

  11. Flare plasma dynamics obseved with the YOHKOH Bragg crystal spectrometer. III. Spectral signatures of electron-beam-heated atmospheres.

    Science.gov (United States)

    Marriska, John. T.

    1995-05-01

    Using numerical simulations of an electon-beam-heated solar flare, we investigate the observational consequences of variations in the electron beam total energy flux and the low-energy cut off value for models with both low and high initial densities. To do this we use the evolution of the physical parameters of the simulated flares to synthesize the time evolution of the spectrum in the wavelength region surrounding tha Ca xix resonance line. These spectra are then summed over a 9 s time interval to simulate typical spectra from the Yohkoh Bragg crystal spectometer and the first three moments are computed for comparison with observational results. This comparison shows that no single low or high initial density model satisfies the observed average behavior of the Ca xix resonance line. Low initial density models produce too large a blue shift velocity, while high initial density model have lines that are too narrow. Comparison of these models with the Yohkok data suggests that the key problem for models of the impulsive phase ofa solar flare is producing significant amounts of stationary hot plasma early in the flare.

  12. Seasonal response of photosynthetic electron transport and energy dissipation in the eighth year of exposure to elevated atmospheric CO{sub 2} (FACE) in Pinus taeda (loblolly pine)

    Energy Technology Data Exchange (ETDEWEB)

    Logan, B.A.; Combs, A.; Kent, R.; Stanley, L. [Bowdoin College, Brunswick, ME (United States). Dept. of Biology; Myers, K. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Biological Sciences; Tissue, D.T. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Biological Sciences; Western Sydney Univ., Richmond, NSW (Australia). Centre for Plant and Food Science

    2009-06-15

    This study investigated the biological adaptation of loblolly pine following long-term seasonal exposure to elevated carbon dioxide (CO{sub 2}) partial pressures (pCO{sub 2}). Exposure to elevated atmospheric CO{sub 2} (pCO{sub 2}) usually results in significant stimulation in light-saturated rates of photosynthetic CO{sub 2} assimilation. Plants are protected against photoinhibition by biochemical processes known as photoprotection, including energy dissipation, which converts excess absorbed light energy into heat. This study was conducted in the eighth year of exposure to elevated pCO{sub 2} at the Duke FACE site. The effect of elevated pCO{sub 2} on electron transport and energy dissipation in the pine trees was examined by coupling the analyses of the capacity for photosynthetic oxygen (O{sub 2}) evolution, chlorophyll fluorescence emission and photosynthetic pigment composition with measurements of net photosynthetic CO{sub 2} assimilation (Asat). During the summer growing season, Asat was 50 per cent higher in current-year needles and 24 per cent higher in year-old needles in elevated pCO{sub 2} in comparison with needles of the same age cohort in ambient pCO{sub 2}. Thus, older needles exhibited greater photosynthetic down-regulation than younger needles in elevated pCO{sub 2}. In the winter, Asat was not significantly affected by growth pCO{sub 2}. Asat was lower in winter than in summer. Growth at elevated pCO{sub 2} had no significant effect on the capacity for photosynthetic oxygen evolution, photosystem 2 efficiencies, chlorophyll content or the size and conversion state of the xanthophyll cycle, regardless of season or needle age. There was no evidence that photosynthetic electron transport or photoprotective energy dissipation responded to compensate for the effects of elevated pCO{sub 2} on Calvin cycle activity. 73 refs., 4 figs.

  13. Electronic quenching of OH(A) by water in atmospheric pressure plasmas and its influence on the gas temperature determination by OH(A-X) emission

    Energy Technology Data Exchange (ETDEWEB)

    Bruggeman, Peter; Schram, Daan C [Department of Applied Physics, Technische Universiteit Eindhoven, PO Box 513, 5600 MB Eindhoven (Netherlands); Iza, Felipe; Kong, Michael G [Department of Electronic and Electrical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom); Guns, Peter; Lauwers, Daniel; Leys, Christophe [Department of Applied Physics, Ghent University, Jozef Plateaustraat 22, B-9000 Ghent (Belgium); Gonzalvo, Yolanda Aranda [Plasma and Surface Analysis Division, Hiden Analytical Ltd, 420 Europa Boulevard, Warrington WA5 7UN (United Kingdom)], E-mail: p.j.bruggeman@tue.nl

    2010-02-15

    In this paper it is shown that electronic quenching of OH(A) by water prevents thermalization of the rotational population distribution of OH(A). This means that the observed ro-vibrational OH(A-X) emission band is (at least partially) an image of the formation process and is determined not only by the gas temperature. The formation of negative ions and clusters for larger water concentrations can contribute to the non-equilibrium. The above is demonstrated in RF excited atmospheric pressure glow discharges in He-water mixtures in a parallel metal plate reactor by optical emission spectroscopy. For this particular case a significant overpopulation of high rotational states appears around 1000 ppm H{sub 2}O in He. The smallest temperature parameter of a non-Boltzmann (two-temperature) distribution fitted to the experimental spectrum of OH(A-X) gives a good representation of the gas temperature. Only the rotational states with the smallest rotational numbers (J {<=} 7) are thermalized and representative for the gas temperature.

  14. Attenuated total reflectance FT-IR imaging and quantitative energy dispersive-electron probe X-ray microanalysis techniques for single particle analysis of atmospheric aerosol particles.

    Science.gov (United States)

    Ryu, JiYeon; Ro, Chul-Un

    2009-08-15

    This work demonstrates the practical applicability of the combined use of attenuated total reflectance (ATR) FT-IR imaging and low-Z particle electron probe X-ray microanalysis (EPMA) techniques for the characterization of individual aerosol particles. These two single particle analytical techniques provide complementary information on the physicochemical characteristics of the same individual particles, that is, the low-Z particle EPMA for the information on the morphology and elemental concentration and the ATR-FT-IR imaging on the functional group, molecular species, and crystal structure. It was confirmed that the ATR-FT-IR imaging technique can provide sufficient FT-IR absorption signals to perform molecular speciation of individual particles of micrometer size when applied to artificially generated aerosol particles such as ascorbic acid and NaNO(3) aerosols. An exemplar indoor atmospheric aerosol sample was investigated to demonstrate the practical feasibility of the combined application of ATR-FT-IR imaging and low-Z particle EPMA techniques for the characterization of individual airborne particles.

  15. Animal evolution and atmospheric pO2: is there a link between gradual animal adaptation to terrain elevation due to Ural orogeny and survival of subsequent hypoxic periods?

    Science.gov (United States)

    Kurbel, Sven

    2014-10-22

    Considering evolution of terrestrial animals as something happening only on flat continental plains seems wrong. Many mountains have arisen and disappeared over the geologic time scale, so in all periods some areas of high altitude existed, with reduced oxygen pressure (pO2) and increased aridity. During orogeny, animal species of the raising terrain can slowly adapt to reduced oxygen levels.This review proposes that animal evolution was often driven by atmospheric oxygen availability. Transitions of insect ancestors and amphibians out of water are here interpreted as events forced by the lack of oxygen in shallow and warm water during Devonian. Hyperoxia during early Carboniferous allowed giant insects to be predators of lowlands, forcing small amphibians to move to higher terrains, unsuitable to large insects due to reduced pO2. In arid mountainous habitats, ascended animals evolved in early reptiles with more efficient lungs and improved circulation. Animals with alveolar lungs became the mammalian ancestors, while those with respiratory duct lungs developed in archosaurs. In this interpretation, limb precursors of wings and pneumatised bones might have been adaptations for moving on steep slopes.Ural mountains have risen to an estimated height of 3000 m between 318 and 251 Mya. The earliest archosaurs have been found on the European Ural side, estimated 275 Myr old. It is proposed that Ural orogeny slowly elevated several highland habitats within the modern Ural region to heights above 2500 m. Since this process took near 60 Myr, animals in these habitats fully to adapted to hypoxia.The protracted P-Tr hypoxic extinction event killed many aquatic and terrestrial animals. Devastated lowland areas were repopulated by mammaliaformes that came down from mountainous areas. Archosaurs were better adapted to very low pO2, so they were forced to descend to the sea level later when the lack of oxygen became severe. During the Triassic period, when the relative content

  16. Absorbed Dose Distributions in Small Copper Wire Insulation due to Multiple-Sided Irradiations by 0.4 MeV Electrons

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.; Pedersen, Walther Batsberg

    1979-01-01

    When scanned electron beams are used to crosslink polymeric insulation of wire and cable, an important goal is to achieve optimum uniformity of absorbed dose distributions. Accurate measurements of dose distributions in a plastic dosimeter simulating a typical insulating material (polyethylene....... and insulation thicknesses between 0.4 and 0.8 mm. The plastic dosimeter simulating polyethylene insulations was a thin radiochromic polyvinyl butyral film wrapped several times around the copper wire, such that when unwrapped and analyzed optically on a scanning microspectrophotometer, high-resolution radial...

  17. Visions of our Planet's Atmosphere, Land and Oceans: NASA/NOAA Electronic-Theater 2002. Spectacular Visualizations of our Blue Marble

    Science.gov (United States)

    Hasler, A. F.; Starr, David (Technical Monitor)

    2002-01-01

    Spectacular Visualizations of our Blue Marble The NASA/NOAA Electronic Theater presents Earth science observations and visualizations in a historical perspective. Fly in from outer space to the 2002 Winter Olympic Stadium Site of the Olympic Opening and Closing Ceremonies in Salt Lake City. Fly in and through Olympic Alpine Venues using 1 m IKONOS "Spy Satellite" data. Go back to the early weather satellite images from the 1960s and see them contrasted with the latest US and international global satellite weather movies including hurricanes & "tornadoes". See the latest visualizations of spectacular images from NASA/NOAA remote sensing missions like Terra, GOES, TRMM, SeaWiFS, Landsat 7 including new 1 - min GOES rapid scan image sequences of Nov 9th 2001 Midwest tornadic thunderstorms and have them explained. See how High-Definition Television (HDTV) is revolutionizing the way we communicate science. (In cooperation with the American Museum of Natural History in NYC). See dust storms in Africa and smoke plumes from fires in Mexico. See visualizations featured on the covers of Newsweek, TIME, National Geographic, Popular Science & on National & International Network TV. New computer software tools allow us to roam & zoom through massive global images e.g. Landsat tours of the US, and Africa, showing desert and mountain geology as well as seasonal changes in vegetation. See animations of the polar ice packs and the motion of gigantic Antarctic Icebergs from SeaWinds data. Spectacular new visualizations of the global atmosphere & oceans are shown. See vertexes and currents in the global oceans that bring up the nutrients to feed tiny algae and draw the fish, whales and fisherman. See the how the ocean blooms in response to these currents and El Nicola Nina climate changes. See the city lights, fishing fleets, gas flares and biomass burning of the Earth at night observed by the "night-vision" DMSP military satellite.

  18. On-site and off-site atmospheric PBDEs in an electronic dismantling workshop in south China: Gas-particle partitioning and human exposure assessment

    Energy Technology Data Exchange (ETDEWEB)

    An Taicheng, E-mail: antc99@gig.ac.cn [State Key Laboratory of Organic Geochemistry, Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Zhang Delin [State Key Laboratory of Organic Geochemistry, Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Li Guiying; Mai Bixian; Fu Jiamo [State Key Laboratory of Organic Geochemistry, Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)

    2011-12-15

    Gas samples and total suspended particle during work and off work time were investigated on-site and off-site electronic waste dismantling workshop (I- and O-EWDW), then compared with plastic recycling workshop (PRW) and waste incineration plant (WIP). TSP concentrations and total PBDE were 0.36-2.21 mg/m{sup 3} and 27-2975 ng/m{sup 3} at different workshops, respectively. BDE-47, -99, and -209 were major {Sigma}PBDE congeners at I-EWDW and WIP, while BDE-209 was only dominant congener in PRW and control sites during work time and all sites during off work time. The gas-particle partitioning result was well correlated with the subcooled liquid vapor pressure for all samples, except for WIP and I-EDWD, at park during work time, and residential area during off work time. The predicted urban curve fitted well with measured {phi} values at O-DEWD during work time, whereas it was slightly overestimated or underestimated for others. Exposure assessment revealed the highest exposure site was I-EDWD. - Highlights: > On- and off-site atmospheric PBDEs was monitored in e-waste dismantling workshops in south China. > The gas-particle partitioning result was well correlated with the subcooled liquid vapor pressure for some samples. > Exposure assessment revealed that workers in I-EDWD were the highest exposure population. - The findings of this study may serve as a valuable reference for future risk assessment and environmental management in Guiyu, South China.

  19. Magneto-thermoelectric effects in the two-dimensional electron gas of a HgTe quantum well due to THz laser heating by cyclotron resonance absorption

    Science.gov (United States)

    Pakmehr, Mehdi; Bruene, Christoph; Buhmann, Hartmut; Molenkamp, Laurens; McCombe, Bruce

    2015-03-01

    HgTe quantum wells (QWs) have shown a number of interesting phenomena over the past 20 years, most recently the first two-dimensional topological insulating state. We have studied thermoelectric photovoltages of 2D electrons in a 6.1 nm wide HgTe quantum well induced by cyclotron resonance absorption (B = 2 - 5 T) of a focused THz laser beam. We have estimated thermo-power coefficients by detailed analysis of the beam profile at the sample surface and the photovoltage signals developed across various contacts of a large Hall bar structure at a bath temperature of 1.6 K. We obtain reasonable values of the magneto-thermopower coefficients. Work at UB was supported by NSF DMR 1008138 and the Office of the Provost, and at the University of Wuerzburg by DARPA MESO Contract N6601-11-1-4105, by DFG Grant HA5893/4-1 within SPP 1666 and the Leibnitz Program, and the EU ERC-AG Program (Project 3-TOP.

  20. A search for the Sunyaev-Zel'dovich effect at millimeter wavelengths. [cosmic background photon energy increase due to Compton scattering by high temperature galactic cluster plasma electrons

    Science.gov (United States)

    Meyer, S. S.; Jeffries, A. D.; Weiss, R.

    1983-01-01

    It is believed that X-ray emission from clusters of galaxies represents thermal bremsstrahlung from a hot plasma. According to Sunyaev and Zel'dovich (1972), the plasma column density and temperature derived from this model imply a measurable distortion of the cosmic background radiation (CBR) in the cluster direction. This distortion results from the Compton scattering of the CBR photons by the electrons in the plasma, resulting in an average increase of each photon. This process, known as the Sunyaev-Zel'dovich effect, is photon conserving and 'shifts' the CBR spectrum to higher frequencies. The result is a decrease of flux at frequencies below 7.5 per cm (the Rayleigh-Jeans region), and an increase above. The investigation is concerned with measurements of the Sunyaev-Zel'dovich effect at frequencies in the range from 3 to 10 per cm. Attention is given to the employed observing and analysis technique, and an initial null result for the cluster Abell 1795.

  1. SU-E-T-325: Dosimetric Impact Due to FlexiShield in Electronic Brachytherapy (eBx) of Breast IORT: A Phantom Study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y; Huynh, J; Ley, M; Gonzalez, V [University of Arizona, Tucson, AZ (United States)

    2015-06-15

    Purpose: To evaluate dosimetric change of eBx plan due to Flexishield. Methods: To simulate a clinically difficult case (skin spacing < 1 cm and touching chest wall), prostheses breast tissue phantom overlaid Xoft spherical balloon applicator. To minimize significant metal streak artifact, megavoltage CT (MVCT) scan was acquired using helical TomoTherapy HiART. Two sets of MVCT images were taken with/without FlexiShield for 15 cases: 4 for small (3–4 cm), 4 for medium (4–5 cm) and 7 for large (5–6 cm) balloon. Total 30 MVCT scans were obtained with 50 % contrast to improve image contrast of balloon relative to breast tissue phantom. Balloon deformation was measured in anterior-posterior (AP) and lateral (LAT) dimensions in the middle of balloon. Skin spacing was also evaluated. Treatment plan was made based on each MVCT scan and two balloon surface doses (AP and LAT directions) and skin dose were compared between plans with/without FlexiShield. Results: The balloon was deformed due to pressure from both FlexiShield (skin side) and FlexiShield mini (chest wall side). Mean ± standard deviation (maximum) value was 1.5 ± 1.0 mm (3.3 mm) for AP compression and 0.4 ± 0.3 mm (1.1 mm) for LAT expansion. Balloon surface dose was increased by 1.8 ± 1.2 Gy (4.9 Gy) at AP point and decreased by 0.4 ± 0.4 Gy (1.3 Gy) at LAT point. Skin spacing was constantly reduced by 1.1 ± 0.8 mm (3 mm). Skin surface dose was increased by 1.5 ± 0.8 Gy (3.3 Gy) and its relative increase was 17.9 ± 9.3% (39.6%). Conclusion: FlexiShield deforms the balloon and reduces skin spacing, thereby resulting in higher dose in AP direction, lower dose in LAT direction, and elevated skin dose compared to the plan without FlexiShield. In the clinic, this balloon deformation and corresponding dose variation should be considered.

  2. 工程爆破中大气污染物的形成机理及控制%The Formation Mechnaism of Atmospheric Pollutants Due to Commercial Blast and its Control

    Institute of Scientific and Technical Information of China (English)

    尹承龙; 黄忆龙; 董平

    2000-01-01

    The paper presents an analysis of the formation mechanism of various atmospheric pollutants resulting from industrial blast,based on types of explosives and their compositions and suggests corresponding control measures,as needed by various contributing factors in an effort to ensure less emission of atmospheric pollutants caused by industrial blast and reduce its adverse influence on atmospheric environment.%依据炸药的种类和组成,分析探讨了工程爆破中各种大气污染物的形成机理,根据各种因素提出了相应的控制措施,以确保减少工程爆破中大气污染物的排放,降低其对大气环境的不利影响。

  3. Martian Dust Devil Electron Avalanche Process and Associated Electrochemistry

    Science.gov (United States)

    Jackson, Telana L.; Farrell, William M.; Delory, Gregory T.; Nithianandam, Jeyasingh

    2010-01-01

    Mars' dynamic atmosphere displays localized dust devils and larger, global dust storms. Based on terrestrial analog studies, electrostatic modeling, and laboratory work these features will contain large electrostatic fields formed via triboelectric processes. In the low-pressure Martian atmosphere, these fields may create an electron avalanche and collisional plasma due to an increase in electron density driven by the internal electrical forces. To test the hypothesis that an electron avalanche is sustained under these conditions, a self-consistent atmospheric process model is created including electron impact ionization sources and electron losses via dust absorption, electron dissociation attachment, and electron/ion recombination. This new model is called the Dust Devil Electron Avalanche Model (DDEAM). This model solves simultaneously nine continuity equations describing the evolution of the primary gaseous chemical species involved in the electrochemistry. DDEAM monitors the evolution of the electrons and primary gas constituents, including electron/water interactions. We especially focus on electron dynamics and follow the electrons as they evolve in the E field driven collisional gas. When sources and losses are self-consistently included in the electron continuity equation, the electron density grows exponentially with increasing electric field, reaching an equilibrium that forms a sustained time-stable collisional plasma. However, the character of this plasma differs depending upon the assumed growth rate saturation process (chemical saturation versus space charge). DDEAM also shows the possibility of the loss of atmospheric methane as a function of electric field due to electron dissociative attachment of the hydrocarbon. The methane destruction rates are presented and can be included in other larger atmospheric models.

  4. k-space drift due to the density variation as a cause of electromagnetic emission generation of type III solar radio bursts by a non-gyrotropic electron beam

    Science.gov (United States)

    Tsiklauri, David; Schmitz, Holger

    2013-04-01

    , in long term evolution of electromagnetic emission generation of type III solar radio bursts. The following improvements and progress in understanding of the radio emission mechanism are made: (i) Improved numerical simulations with larger spatial domain and longer end-simulation times; (ii) The electron beam injection on a density plateau followed by a decreasing density gradient that mimics the Sun-earth system; (iii) Consideration of a ring and shifted ring electron initial velocity distribution functions; (iv) The role of the k-space drift in the radio emission; (v) Estimation of the ECM growth rate and its role in the emission generation. It is worthwhile to note that Ref.[3] proposed mode coupling on the density gradient as a source of radio emission as opposed to the k-space drift advocated in the present work. The situation is analogous to the auroral waves emitted near the plasma frequency in Earth auroral ionosphere [A. Layden, I. H. Cairns, P. A. Robinson, and J. LaBelle, J. Geophys. Res. 116, A12328 (2011)]. [1] D. Tsiklauri, "An alternative to the plasma emission model: Particle-In-Cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts", Physics of Plasmas 18, 052903 (2011) [2] R. Pechhacker, D. Tsiklauri, "The effect of electron beam pitch angle and density gradient on solar type III radio bursts", Phys. Plasmas 19, 112903 (2012) [3] R. Pechhacker, D. Tsiklauri, "Electron cyclotron maser emission mode coupling to the z-mode on a longitudinal density gradient in the context of solar type III bursts", Phys. Plasmas 19, 110702 (2012) [4] H. Schmitz, D. Tsiklauri, "k-space drift due to the density variation as a cause of electromagnetic emission generation of type III solar radio bursts by a non-gyrotropic electron beam", Phys. Plasmas, in preparation, (2013)

  5. Estimation of electron concentration in plasma and plasma frequency in the vicinity of a hypersonic aircraft that moves in atmosphere and analysis of propagation frequencies of electromagnetic waves in such plasma

    Science.gov (United States)

    Fedorov, V. A.

    2016-05-01

    Electron concentration in plasma and plasma frequency are estimated for the plasma that is formed in the vicinity of a hypersonic aircraft that moves in atmosphere. The frequencies of electromagnetic waves that may propagate in plasma emerging in the vicinity of the aircraft are determined. Formulas that make it possible to analytically (rather than graphically) calculate electron concentration in plasma at altitudes of 30, 60, and 90 km are derived for two speeds. Several specific features of variations in the electron concentration in plasma depending on the above altitudes and speeds are presented. Quasi-periodic variations in the plasma concentration can be obtained using an increase and decrease in the speed of aircraft.

  6. Modeling of polarization phenomena due to RF sheaths and electron beams in magnetized plasma; Modelisation de phenomenes de polarisation par des gaines rf et des faisceaux electroniques dans un plasma magnetise

    Energy Technology Data Exchange (ETDEWEB)

    Faudot, E

    2005-07-01

    This work investigates the problematic of hot spots induced by accelerated particle fluxes in tokamaks. It is shown that the polarization due to sheaths in the edge plasma in which an electron beam at a high level of energy is injected, can reach several hundreds volts and thus extend the deposition area. The notion of obstructed sheath is introduced and explains the acceleration of energy deposition by the decreasing of the sheath potential. Then, a 2-dimensional fluid modeling of flux tubes in front of ICRF antennae allows us to calculate the rectified potentials taking into account RF polarization currents transverse to magnetic field lines. The 2-dimensional fluid code designed validates the analytical results which show that the DC rectified potential is 50% greater with polarization currents than without. Finally, the simultaneous application of an electron beam and a RF potential reveals that the potentials due to each phenomenon are additives when RF potential is much greater than beam polarization. The density depletion of polarized flux tubes in 2-dimensional PIC (particles in cells) simulations is characterized but not yet explained. (author)

  7. Methodology for the accelerated simulation of the deterioration that by atmospheric corrosion appears in electronic equipment; Metodologia para la simulacion acelerada del deterioro que por corrosion atmosferica se presenta en equipo electronico

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz Prado, A.; Schouwenaars, R.; Cerrud Sanchez, S.M. [Facultad de Ingenieria, UNAM, Mexico, D.F. (Mexico)

    2002-12-01

    The corrosion resistance of systems and electronic parts which are designed to work in atmospheric conditions have been tested for decades; some of these methods were the Cyclic Humidity Test, Field Tests and Salt Spray (Fog) Testing, the latter was one of the most popular methods. However, the salt spray test and most of the other existing methods do not show strong relationships with the real conditions of service. For this reason, it is necessary to develop appropriated methods and equipment for the accelerated simulation of real atmospheric corrosion phenomena. This article seeks to demonstrate the need to develop a test and the necessary equipment to reproduce the damage in electronic systems and equipment by atmospheric corrosion. [Spanish] Para la evaluacion de la resistencia a la corrosion de sistemas y equipo electronico que trabajaran bajo condiciones de deterioro generadas por el medio ambiente, se han aplicado una serie de ensayos, donde el mas popular es el de camara de niebla salina. Sin embargo, este y otros que se han elaborado para tal efecto no tienen ninguna relacion con las condiciones reales de servicio, por lo que es necesario un metodo de evaluacion que permita simular de forma acelerada los fenomenos de deterioro por efectos ambientales. Este articulo pretende demostrar la necesidad de desarrollar una prueba, que en forma acelerada, reproduzca el dano que sufre el material por efecto de la atmosfera; el cual se orienta a la evaluacion de equipo electrico y electronico.

  8. Staging atmospheres

    DEFF Research Database (Denmark)

    Bille, Mikkel; Bjerregaard, Peter; Sørensen, Tim Flohr

    2015-01-01

    The article introduces the special issue on staging atmospheres by surveying the philosophical, political and anthropological literature on atmosphere, and explores the relationship between atmosphere, material culture, subjectivity and affect. Atmosphere seems to occupy one of the classic...... localities of tensions between matter and the immaterial, the practical and the ideal, and subject and object. In the colloquial language there can, moreover, often seem to be something authentic or genuine about atmosphere, juxtaposing it to staging, which is implied to be something simulated or artificial....... This introduction seeks to outline how a number of scholars have addressed the relationship between staged atmospheres and experience, and thus highlight both the philosophical, social and political aspects of atmospheres...

  9. Influence of gas atmospheres and ceria on the stability of nanoporous gold studied by environmental electron microscopy and In situ ptychography

    DEFF Research Database (Denmark)

    Baier, Sina; Wittstock, Arne; Damsgaard, Christian Danvad

    2016-01-01

    was determined by IR thermography. While using elevated temperatures (room temperature - 400 °C) and realistic gas atmospheres (1 bar) we achieved for the first time a spatial resolution of about 20 nm during hard X-ray ptychography. The annealing of pure and ceria stabilized nanoporous gold in different...

  10. Fast pulsed operation of a small non-radioactive electron source with continuous emission current control.

    Science.gov (United States)

    Cochems, P; Kirk, A T; Bunert, E; Runge, M; Goncalves, P; Zimmermann, S

    2015-06-01

    Non-radioactive electron sources are of great interest in any application requiring the emission of electrons at atmospheric pressure, as they offer better control over emission parameters than radioactive electron sources and are not subject to legal restrictions. Recently, we published a simple electron source consisting only of a vacuum housing, a filament, and a single control grid. In this paper, we present improved control electronics that utilize this control grid in order to focus and defocus the electron beam, thus pulsing the electron emission at atmospheric pressure. This allows short emission pulses and excellent stability of the emitted electron current due to continuous control, both during pulsed and continuous operations. As an application example, this electron source is coupled to an ion mobility spectrometer. Here, the pulsed electron source allows experiments on gas phase ion chemistry (e.g., ion generation and recombination kinetics) and can even remove the need for a traditional ion shutter.

  11. Exoplanet Atmospheres

    CERN Document Server

    Seager, S

    2010-01-01

    At the dawn of the first discovery of exoplanets orbiting sun-like stars in the mid-1990s, few believed that observations of exoplanet atmospheres would ever be possible. After the 2002 Hubble Space Telescope detection of a transiting exoplanet atmosphere, many skeptics discounted it as a one-object, one-method success. Nevertheless, the field is now firmly established, with over two dozen exoplanet atmospheres observed today. Hot Jupiters are the type of exoplanet currently most amenable to study. Highlights include: detection of molecular spectral features; observation of day-night temperature gradients; and constraints on vertical atmospheric structure. Atmospheres of giant planets far from their host stars are also being studied with direct imaging. The ultimate exoplanet goal is to answer the enigmatic and ancient question, "Are we alone?" via detection of atmospheric biosignatures. Two exciting prospects are the immediate focus on transiting super Earths orbiting in the habitable zone of M-dwarfs, and u...

  12. Articulating Atmospheres

    DEFF Research Database (Denmark)

    Kinch, Sofie

    2011-01-01

    This paper presents an architectural approach to designing computational interfaces by articulating the notion of atmosphere in the field of interaction design. It draws upon the concept of kinesthetic interaction and a philosophical notion on atmosphere emphasizing the importance of bodily...... experience in space, presented as middle ground experience. In the field of HCI, middle ground experiences complete the unarticulated spectrum between designing for foreground of attention or background awareness. When “Articulating Atmospheres through Middle Ground Experiences in Interaction Design...

  13. Atmospheric electricity

    CERN Document Server

    Chalmers, J Alan

    1957-01-01

    Atmospheric Electricity brings together numerous studies on various aspects of atmospheric electricity. This book is composed of 13 chapters that cover the main problems in the field, including the maintenance of the negative charge on the earth and the origin of the charges in thunderstorms. After a brief overview of the historical developments of atmospheric electricity, this book goes on dealing with the general principles, results, methods, and the MKS system of the field. The succeeding chapters are devoted to some aspects of electricity in the atmosphere, such as the occurrence and d

  14. On the use of the double floating probe method to infer the difference between the electron and the heavy particles temperatures in an atmospheric pressure, vortex-stabilized nitrogen plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Prevosto, L., E-mail: prevosto@waycom.com.ar; Mancinelli, B. R. [Grupo de Descargas Eléctricas, Departamento Ingeniería Electromecánica, Facultad Regional Venado Tuerto (UTN), Laprida 651, 2600 Venado Tuerto, Santa Fe (Argentina); Kelly, H. [Grupo de Descargas Eléctricas, Departamento Ingeniería Electromecánica, Facultad Regional Venado Tuerto (UTN), Laprida 651, 2600 Venado Tuerto, Santa Fe (Argentina); Instituto de Física del Plasma (CONICET), Departamento de Física, Facultad de Ciencias Exactas y Naturales (UBA) Ciudad Universitaria Pab. I, 1428 Buenos Aires (Argentina)

    2014-05-15

    Sweeping double probe measurements in an atmospheric pressure direct current vortex-stabilized plasma jet are reported (plasma conditions: 100 A discharge current, N{sub 2} gas flow rate of 25 Nl/min, thoriated tungsten rod-type cathode, copper anode with 5 mm inner diameter). The interpretation of the double probe characteristic was based on a generalization of the standard double floating probe formulae for non-uniform plasmas coupled to a non-equilibrium plasma composition model. Perturbations caused by the current to the probe together with collisional and thermal processes inside the probe perturbed region were taken into account. Radial values of the average electron and heavy particle temperatures as well as the electron density were obtained. The calculation of the temperature values did not require any specific assumption about a temperature relationship between different particle species. An electron temperature of 10 900 ± 900 K, a heavy particle temperature of 9300 ± 900 K, and an electron density of about 3.5 × 10{sup 22} m{sup −3} were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found toward the outer border of the plasma jet. These results showed good agreement with those previously reported by the authors by using a single probe technique. The calculations have shown that this method is particularly useful for studying spraying-type plasma torches operated at power levels of about 15 kW.

  15. On the use of the double floating probe method to infer the difference between the electron and the heavy particles temperatures in an atmospheric pressure, vortex-stabilized nitrogen plasma jet.

    Science.gov (United States)

    Prevosto, L; Kelly, H; Mancinelli, B R

    2014-05-01

    Sweeping double probe measurements in an atmospheric pressure direct current vortex-stabilized plasma jet are reported (plasma conditions: 100 A discharge current, N2 gas flow rate of 25 Nl/min, thoriated tungsten rod-type cathode, copper anode with 5 mm inner diameter). The interpretation of the double probe characteristic was based on a generalization of the standard double floating probe formulae for non-uniform plasmas coupled to a non-equilibrium plasma composition model. Perturbations caused by the current to the probe together with collisional and thermal processes inside the probe perturbed region were taken into account. Radial values of the average electron and heavy particle temperatures as well as the electron density were obtained. The calculation of the temperature values did not require any specific assumption about a temperature relationship between different particle species. An electron temperature of 10,900 ± 900 K, a heavy particle temperature of 9300 ± 900 K, and an electron density of about 3.5 × 10(22) m(-3) were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found toward the outer border of the plasma jet. These results showed good agreement with those previously reported by the authors by using a single probe technique. The calculations have shown that this method is particularly useful for studying spraying-type plasma torches operated at power levels of about 15 kW.

  16. Adsorption of Atmospheric Gases on Pu Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, A J; Holliday, K S; Stanford, J A; Grant, W K; Erler, R G; Allen, P G; McLean, W; Roussel, P

    2012-03-29

    Surface adsorption represents a competition between collision and scattering processes that depend on surface energy, surface structure and temperature. The surface reactivity of the actinides can add additional complexity due to radiological dissociation of the gas and electronic structure. Here we elucidate the chemical bonding of gas molecules adsorbed on Pu metal and oxide surfaces. Atmospheric gas reactions were studied at 190 and 300 K using x-ray photoelectron spectroscopy. Evolution of the Pu 4f and O 1s core-level states were studied as a function of gas dose rates to generate a set of Langmuir isotherms. Results show that the initial gas dose forms Pu{sub 2}O{sub 3} on the Pu metal surface followed by the formation of PuO{sub 2} resulting in a layered oxide structure. This work represents the first steps in determining the activation energy for adsorption of various atmospheric gases on Pu.

  17. Atmospheric materiality

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2016-01-01

    experience and, consequently, to the conceptual and methodological shifts in the production of space, and hence in the way we think about materiality. In this context, architectural space is understood as a contingent construction – a space of engagement that appears to us as a result of continuous...... characteristics of atmosphere as a spatial phenomenon, the aim of this text is to illustrate these associations and draw out design protocols, focusing on ways in which atmosphere can be conditioned architecturally. In other words, the objective is to trace the conceptual contours of ‘atmospheric materiality’....

  18. Nonthermal rotational distribution of CO/A 1Pi/ fragments produced by dissociative excitation of CO2 by electron impact. [in Mars atmosphere

    Science.gov (United States)

    Mumma, M. J.; Stone, E. J.; Zipf, E. C.

    1975-01-01

    Measurements were made of the rotational profiles of specific bands of the CO fourth-positive group (4PG). The CO 4PG bands were excited by electron impact dissociative excitation of CO2. The results are applicable to analysis of the Mariner observations of the CO 4PG in the dayglow of Mars. The results indicate that dissociative excitation of CO2 by electron impact leads to CO(A 1Pi) fragments with a rotational distribution that is highly nonthermal. The parent CO2 temperature was about 300 K in the experiment, while the fragment CO(A 1Pi) showed emission band profiles consistent with a rotational temperature greater than about 1500 K. Laboratory measurement of the reduced transmission of the hot bands by thermal CO appears to be the most direct way of determining the column density responsible for the CO(v',0) absorption of Mars.

  19. Atmospheric Dispositifs

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2015-01-01

    , the conceptual foundations and protocols for the production of atmosphere in architecture might be found beneath the surface of contemporary debates. In this context, the notion of atmospheric dispositif – illustrated through an oeuvre of the German architect Werner Ruhnau and its theoretical and historical...... as a spatial phenomenon, exploring a multiplicity of conditions that constitute their resonant origins – i.e. the production sites from and within they have emerged. The intention is also to argue that despite the fact that atmosphere as an aesthetic category has crystallised over the last few decades...... contextualisation – provides a platform for revealing productive entanglements between heterogeneous elements, disciplines and processes. It also allows rendering atmosphere as a site of co-production open to contingencies and affective interplay on multiples levels: at the moment of its conceptualisation...

  20. Atmospheric composition

    Science.gov (United States)

    Daniels, G. E.

    1973-01-01

    The earth's atmosphere is made up of a number of gases in different relative amounts. Near sea level and up to about 90 km, the amount of these atmospheric gases in clean, relatively dry air is practically constant. Four of these gases, nitrogen, oxygen, argon, and carbon dioxide, make up 99.99 percent by volume of the atmosphere. Two gases, ozone and water vapor, change in relative amounts, but the total amount of these two is very small compared to the amount of the other gases. The atmospheric composition shown in a table can be considered valid up to 90 km geometric altitude. Above 90 km, mainly because of molecular dissociation and diffusive separation, the composition changes.

  1. Accurate gamma and MeV-electron track reconstruction with an ultra-low diffusion Xenon/TMA TPC at 10 atmospheres

    CERN Document Server

    González-Díaz, Diego; Borges, F.I.G.; Camargo, M.; Cárcel, S.; Cebrián, S.; Cervera, A.; Conde, C.A.N.; Dafni, T.; Díaz, J.; Esteve, R.; Fernandes, L.M.P.; Ferrario, P.; Ferreira, A.L.; Freitas, E.D.C.; Gehman, V.M.; Goldschmidt, A.; Gómez-Cadenas, J.J.; Gutiérrez, R.M.; Hauptman, J.; Hernando Morata, J.A.; Herrera, D.C.; Irastorza, I.G.; Labarga, L.; Laing, A.; Liubarsky, I.; Lopez-March, N.; Lorca, D.; Losada, M.; Luzón, G.; Marí, A.; Martín-Albo, J.; Martínez-Lema, G.; Martínez, A.; Miller, T.; Monrabal, F.; Monserrate, M.; Monteiro, C.M.B.; Mora, F.J.; Moutinho, L.M.; Muñoz Vidal, J.; Nebot-Guinot, M.; Nygren, D.; Oliveira, C.A.B.; Pérez, J.; Pérez Aparicio, J.L.; Querol, M.; Renner, J.; Ripoll, L.; Rodríguez, J.; Santos, F.P.; dos Santos, J.M.F.; Serra, L.; Shuman, D.; Simón, A.; Sofka, C.; Sorel, M.; Toledo, J.F.; Torrent, J.; Tsamalaidze, Z.; Veloso, J.F.C.A.; Villar, J.A.; Webb, R.; White, J.T.; Yahlali, N.; Azevedo, C.; Aznar, F.; Calvet, D.; Castel, J.; Ferrer-Ribas, E.; García, J.A.; Giomataris, I.; Gómez, H.; Iguaz, F.J.; Lagraba, A.; Le Coguie, A.; Mols, J.P.; Şahin, Ö.; Rodríguez, A.; Ruiz-Choliz, E.; Segui, L.; Tomás, A.; Veenhof, R.

    2015-01-01

    We report the performance of a 10 atm Xenon/trimethylamine time projection chamber (TPC) for the detection of X-rays (30 keV) and gamma-rays (0.511-1.275 MeV) in conjunction with the accurate tracking of the associated electrons. When operated at such a high pressure and in 1%-admixtures, trimethylamine (TMA) endows Xenon with an extremely low electron diffusion (1.3 +-0.13 mm-sigma (longitudinal), 0.8 +-0.15 mm-sigma (transverse) along 1 m drift) besides forming a convenient Penning-Fluorescent mixture. The TPC, that houses 1.1 kg of gas in its active volume, operated continuously for 100 live-days in charge amplification mode. The readout was performed through the recently introduced microbulk Micromegas technology and the AFTER chip, providing a 3D voxelization of 8mm x 8mm x 1.2mm for approximately 10 cm/MeV-long electron tracks. This work was developed as part of the R&D program of the NEXT collaboration for future detector upgrades in the search of the 0bbnu decay in 136Xe, specifically those based ...

  2. Electron paramagnetic resonance line shifts and line shape changes due to heisenberg spin exchange and dipole-dipole interactions of nitroxide free radicals in liquids 8. Further experimental and theoretical efforts to separate the effects of the two interactions.

    Science.gov (United States)

    Peric, Mirna; Bales, Barney L; Peric, Miroslav

    2012-03-22

    The work in part 6 of this series (J. Phys. Chem. A 2009, 113, 4930), addressing the task of separating the effects of Heisenberg spin exchange (HSE) and dipole-dipole interactions (DD) on electron paramagnetic resonance (EPR) spectra of nitroxide spin probes in solution, is extended experimentally and theoretically. Comprehensive measurements of perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl (pDT) in squalane, a viscous alkane, paying special attention to lower temperatures and lower concentrations, were carried out in an attempt to focus on DD, the lesser understood of the two interactions. Theoretically, the analysis has been extended to include the recent comprehensive treatment by Salikhov (Appl. Magn. Reson. 2010, 38, 237). In dilute solutions, both interactions (1) introduce a dispersion component, (2) broaden the lines, and (3) shift the lines. DD introduces a dispersion component proportional to the concentration and of opposite sign to that of HSE. Equations relating the EPR spectral parameters to the rate constants due to HSE and DD have been derived. By employing nonlinear least-squares fitting of theoretical spectra to a simple analytical function and the proposed equations, the contributions of the two interactions to items 1-3 may be quantified and compared with the same parameters obtained by fitting experimental spectra. This comparison supports the theory in its broad predictions; however, at low temperatures, the DD contribution to the experimental dispersion amplitude does not increase linearly with concentration. We are unable to deduce whether this discrepancy is due to inadequate analysis of the experimental data or an incomplete theory. A new key aspect of the more comprehensive theory is that there is enough information in the experimental spectra to find items 1-3 due to both interactions; however, in principle, appeal must be made to a model of molecular diffusion to separate the two. The permanent diffusion model is used to

  3. A study of the atmospherically important reactions of dimethylsulfide (DMS) with I2 and ICl using infrared matrix isolation spectroscopy and electronic structure calculations.

    Science.gov (United States)

    Beccaceci, Sonya; Armata, Nerina; Ogden, J Steven; Dyke, John M; Rhyman, Lydia; Ramasami, Ponnadurai

    2012-02-21

    The reactions of dimethylsulfide (DMS) with molecular iodine (I(2)) and iodine monochloride (ICl) have been studied by infrared matrix isolation spectroscopy by co-condensation of the reagents in an inert gas matrix. Molecular adducts of DMS + I(2) and DMS + ICl have also been prepared using standard synthetic methods. The vapour above each of these adducts trapped in an inert gas matrix gave the same infrared spectrum as that recorded for the corresponding co-condensation reaction. In each case, the infrared spectrum has been interpreted in terms of a van der Waals adduct, DMS : I(2) and DMS : ICl, with the aid of infrared spectra computed for their minimum energy structures at the MP2 level. Computed relative energies of minima and transition states on the potential energy surfaces of these reactions were used to understand why they do not proceed further than the reactant complexes DMS : I(2) and DMS : ICl. The main findings of this research are compared with results obtained earlier for the DMS + Cl(2) and DMS + Br(2) reactions, and the atmospheric implications of the conclusions are also considered.

  4. Atmospheric Photochemistry

    Science.gov (United States)

    Massey, Harrie; Potter, A. E.

    1961-01-01

    The upper atmosphere offers a vast photochemical laboratory free from solid surfaces, so all reactions take place in the gaseous phase. At 30 km altitude the pressure has fallen to about one-hundredth of that at ground level, and we shall, rather arbitrarily, regard the upper atmosphere as beginning at that height. By a little less than 100 km the pressure has fallen to 10(exp -3) mm Hg and is decreasing by a power of ten for every 15 km increase in altitude. Essentially we are concerned then with the photochemistry of a nitrogen-oxygen mixture under low-pressure conditions in which photo-ionization, as well as photodissociation, plays an important part. Account must also be taken of the presence of rare constituents, such as water vapour and its decomposition products, including particularly hydroxyl, oxides of carbon, methane and, strangely enough, sodium, lithium and calcium. Many curious and unfamiliar reactions occur in the upper atmosphere. Some of them are luminescent, causing the atmosphere to emit a dim light called the airglow. Others, between gaseous ions and neutral molecules, are almost a complete mystery at this time. Similar interesting phenomena must occur in other planetary atmospheres, and they might be predicted if sufficient chemical information were available.

  5. Atmospheric thermodynamics

    CERN Document Server

    Iribarne, J V

    1973-01-01

    The thermodynamics of the atmosphere is the subject of several chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fill this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can playa role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the first four chapters), they are only briefly discussed, and emphasis is laid on those topics that will be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics of irreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a...

  6. Seasonal response of photosynthetic electron transport and energy dissipation in the eighth year of exposure to elevated atmospheric CO2 (FACE) in Pinus taeda (loblolly pine).

    Science.gov (United States)

    Logan, Barry A; Combs, Andrew; Myers, Kalisa; Kent, Rose; Stanley, Lela; Tissue, David T

    2009-06-01

    To determine the effect of growth under elevated CO(2) partial pressures (pCO(2)) on photosynthetic electron transport and photoprotective energy dissipation, we examined light-saturated net photosynthetic CO(2) assimilation (A(sat)), the capacity for photosynthetic O(2) evolution, chlorophyll fluorescence emission and the pigment composition of upper-canopy loblolly pine needles in the eighth year of exposure to elevated pCO(2) (20 Pa above ambient) at the free-air CO(2) enrichment facility in the Duke Forest. During the summer growing season, A(sat) was 50% higher in current-year needles and 24% higher in year-old needles in elevated pCO(2) in comparison with needles of the same age cohort in ambient pCO(2). Thus, photosynthetic down-regulation at elevated pCO(2) was observed in the summer in year-old needles. In the winter, A(sat) was not significantly affected by growth pCO(2). Reductions in A(sat), the capacity for photosynthetic O(2) evolution and photosystem II (PSII) efficiency in the light-acclimated and fully-oxidized states were observed in the winter when compared to summer. Growth at elevated pCO(2) had no significant effect on the capacity for photosynthetic O(2) evolution, PSII efficiencies in the light-acclimated and fully-oxidized states, chlorophyll content or the size and conversion state of the xanthophyll cycle, regardless of season or needle age cohort. Therefore, we observed no evidence that photosynthetic electron transport or photoprotective energy dissipation responded to compensate for the effects of elevated pCO(2) on Calvin cycle activity.

  7. Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

    CERN Document Server

    Helling, Ch; Rodriguez-Barrera, I M; Wood, Kenneth; Robertson, G B; Stark, C R

    2016-01-01

    Brown dwarfs and giant gas extrasolar planets have cold atmospheres with a rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral cloud particles are charged due to triboelectric processes in such dynamic atmospheres. The dynamics of the atmospheric gas is driven by the irradiating host star and/or by the rotation of the objects that changes during its lifetime. Thermal gas ionisation in these ultra-cool but dense atmospheres allows electrostatic interactions and magnetic coupling of a substantial atmosphere volume. Combined with a strong magnetic field $\\gg B_{\\rm Earth}$, a chromosphere and aurorae might form as suggested by radio and X-ray observations of brown dwarfs. Non-equilibrium processes like cosmic ray ionisation and discharge processes in clouds will increase the local pool of free electrons in the gas. Cosmic rays and lighting discharges also alter the composition of the local atmospheri...

  8. Atmospheric Refraction

    CERN Document Server

    Nauenberg, Michael

    2016-01-01

    Calculations of atmospheric refraction are generally based on a simplified model of atmospheric density in the troposphere which assumes that the temperature decreases at a constant lapse rate from sea level up to a height equal to eleven km, and that afterwards it remains constant. In this model, the temperature divided by the lapse rate determines the length scale in the calculations for altitudes less than this height. But daily balloon measurements across the U.S.A. reveal that in some cases the air temperature actually increases from sea level up to a height of about one km, and only after reaching a plateau, it decreases at an approximately constant lapse rate. Moreover, in three examples considered here, the temperature does not remain constant at eleven km , but continues to decreases to a minimum at about sixteen kilometers , and then increases at higher altitudes at a lower rate. Calculations of atmospheric refraction based on this atmospheric data is compared with the results of simplified models.

  9. Localization of electrons due to orbitally ordered bi-stripes in the bilayer manganite La2-2xSr1+2xMn2O7 (x ∼ 0.59)

    Science.gov (United States)

    Sun, Z.; Wang, Q.; Fedorov, A. V.; Zheng, H.; Mitchell, J. F.; Dessau, D. S.

    2011-01-01

    Electronic phases with stripe patterns have been intensively investigated for their vital roles in unique properties of correlated electronic materials. How these real-space patterns affect the conductivity and other properties of materials (which are usually described in momentum space) is one of the major challenges of modern condensed matter physics. By studying the electronic structure of La2-2xSr1+2xMn2O7 (x ∼ 0.59) and in combination with earlier scattering measurements, we demonstrate the variation of electronic properties accompanying the melting of so-called bi-stripes in this material. The static bi-stripes can strongly localize the electrons in the insulating phase above Tc ∼ 160 K, while the fraction of mobile electrons grows, coexisting with a significant portion of localized electrons when the static bi-stripes melt below Tc. The presence of localized electrons below Tc suggests that the melting bi-stripes exist as a disordered or fluctuating counterpart. From static to melting, the bi-stripes act as an atomic-scale electronic valve, leading to a “colossal” metal-insulator transition in this material. PMID:21715662

  10. On-site and off-site atmospheric PBDEs in an electronic dismantling workshop in south China: gas-particle partitioning and human exposure assessment.

    Science.gov (United States)

    An, Taicheng; Zhang, Delin; Li, Guiying; Mai, Bixian; Fu, Jiamo

    2011-12-01

    Gas samples and total suspended particle during work and off work time were investigated on-site and off-site electronic waste dismantling workshop (I- and O-EWDW), then compared with plastic recycling workshop (PRW) and waste incineration plant (WIP). TSP concentrations and total PBDE were 0.36-2.21 mg/m(3) and 27-2975 ng/m(3) at different workshops, respectively. BDE-47, -99, and -209 were major ∑PBDE congeners at I-EWDW and WIP, while BDE-209 was only dominant congener in PRW and control sites during work time and all sites during off work time. The gas-particle partitioning result was well correlated with the subcooled liquid vapor pressure for all samples, except for WIP and I-EDWD, at park during work time, and residential area during off work time. The predicted urban curve fitted well with measured φ values at O-DEWD during work time, whereas it was slightly overestimated or underestimated for others. Exposure assessment revealed the highest exposure site was I-EDWD.

  11. Intensifying the Atmospheric

    DEFF Research Database (Denmark)

    Liebst, Lasse Suonperä

    2012-01-01

    The phenomenological concept of urban atmospheres is more often applied as an aesthetic description of the metropolitan space as such. This conceptualization is supported in this paper; however, I strive to give the concept a post-phenomenological axial turn. While phenomenology, due to its under...... sufficiently intense. All things considered, the paper should be read as a sociological contribution to theoretically reconstruct the concept of urban atmospheres in the light of spatial morphology.......The phenomenological concept of urban atmospheres is more often applied as an aesthetic description of the metropolitan space as such. This conceptualization is supported in this paper; however, I strive to give the concept a post-phenomenological axial turn. While phenomenology, due to its...... are ‘compressed’ by the spatial morphologies of urban space. In this perspective atmospheres are to be understood as an emergent property that develops when the spatial morphological compression of urban life passes a certain threshold, that is, when the affective rhythm of the urban assemblages becomes...

  12. Atmospheric Neutrinos

    CERN Document Server

    Gaisser, Thomas K

    2016-01-01

    In view of the observation by IceCube of high-energy astrophysical neutrinos, it is important to quantify the uncertainty in the background of atmospheric neutrinos. There are two sources of uncertainty, the imperfect knowledge of the spectrum and composition of the primary cosmic rays that produce the neutrinos and the limited understanding of hadron production, including charm, at high energy. This paper is an overview of both aspects.

  13. Atmospheric and aerosol chemistry

    Energy Technology Data Exchange (ETDEWEB)

    McNeill, V. Faye [Columbia Univ., New York, NY (United States). Dept. of Chemical Engineering; Ariya, Parisa A. (ed.) [McGill Univ. Montreal, QC (Canada). Dept. of Chemistry; McGill Univ. Montreal, QC (Canada). Dept. of Atmospheric and Oceanic Sciences

    2014-09-01

    This series presents critical reviews of the present position and future trends in modern chemical research. Short and concise reports on chemistry, each written by the world renowned experts. Still valid and useful after 5 or 10 years. More information as well as the electronic version of the whole content available at: springerlink.com. Christian George, Barbara D'Anna, Hartmut Herrmann, Christian Weller, Veronica Vaida, D. J. Donaldson, Thorsten Bartels-Rausch, Markus Ammann Emerging Areas in Atmospheric Photochemistry. Lisa Whalley, Daniel Stone, Dwayne Heard New Insights into the Tropospheric Oxidation of Isoprene: Combining Field Measurements, Laboratory Studies, Chemical Modelling and Quantum Theory. Neil M. Donahue, Allen L. Robinson, Erica R. Trump, Ilona Riipinen, Jesse H. Kroll Volatility and Aging of Atmospheric Organic Aerosol. P. A. Ariya, G. Kos, R. Mortazavi, E. D. Hudson, V. Kanthasamy, N. Eltouny, J. Sun, C. Wilde Bio-Organic Materials in the Atmosphere and Snow: Measurement and Characterization V. Faye McNeill, Neha Sareen, Allison N. Schwier Surface-Active Organics in Atmospheric Aerosols.

  14. Studies of suprathermal emission due to cyclotron-electronic heating of the tokamak TCV plasma; Etudes du rayonnement suprathermique emis lors du chauffage cyclotronique electronique du plasma du tokamak TCV

    Energy Technology Data Exchange (ETDEWEB)

    Blanchard, P

    2002-07-01

    Photo sensitization of wide band gap semiconductors is used in a wide range of application like silver halide photography and xerography. The development of a new type of solar cells, based on the sensitization of meso porous metal oxide films by panchromatic dyes, has triggered a lot of fundamental research on electron transfer dynamics. Upon excitation, the sensitizer transfers an electron in the conduction band of the semiconductor. Recombination of the charge separated state is prevented by the fast regeneration of the dye by an electron donor present in solution. Until recently, most of the work in this area has been focused on the competition between the recombination and the regeneration processes, which take place in the nanosecond to millisecond regime. With the development of solid-state femtosecond laser, the measurement of the dynamics of the first electron transfer step occurring in the solar cell has become possible . Electron injection from ruthenium(Il) poly pyridyl complexes into titanium dioxide has been found to occur with a poly exponential rate, with time constants ranging from < 100 fs up to > 10 ps. In spite of the lately acquired capacity to measure the dynamics of these reactions, the physical meaning of this poly exponential kinetics and the factors that can influence this process are still poorly understood. In this work, the development of a new femtosecond pump-probe spectrometer, intended to monitor the ultrafast dynamics of electron injection, is presented. The study of this process requires an excellent temporal resolution and a large wavelength tunability to be able to excite a great variety of dyes and to probe the different products of the reaction. These specifications were met using the latest progress made in optical parametric amplification, which allowed the construction of a versatile experimental set-up. The interfacing by computer of the different devices used during the experiments increase the ease of use of the set

  15. Alarming atmospheres

    DEFF Research Database (Denmark)

    Højlund, Marie; Kinch, Sofie

    2014-01-01

    . As a response to this situation, our design artefact, the interactive furniture Kidkit, invites children to become accustomed to the alarming sounds sampled from the ward while they are waiting in the waiting room. Our design acknowledges how atmospheres emerge as temporal negotiations between the rhythms......, a familiar relationship with the alarming sounds in the ward, enabling her to focus later more on the visit with the relative. The article discusses the proposed design strategy behind this solution and the potentiality for its use in hospital environments in general....

  16. Astronomy and Atmospheric Optics

    Science.gov (United States)

    Cowley, Les; Gaina, Alex

    2011-12-01

    The authors discusse the insuccess of the observation of the Total Eclipse of the Moon from 10 december 2011 in Romania and relate them with meteoconditions. Only a very short part of the last penumbral phase was observed, while the inital part and the totality was not observed due to very dense clouds. The change in color and brightness during this phase was signaled. Meanwhile, there is an area of science where clouds are of great use and interest. This area is Atmospheric optics, while the science which study clouds is meteorology. Clouds in combination with Solar and Moon light could give rise to a variety of strange, rare and unobvious phenomena in the atmosphere (sky), sometimes confused with Unidentified Flying Objects (UFO). The importance of meteorology for astronomy and atmospheric optics is underlined and an invitation to astronomers to use unfavourable days for athmospheric observations was sent. The web address of the site by Les Cowley, designed for atmospheric optics phenomena is contained in the text of the entry.

  17. History and modern applications of nano-composite materials carrying GA/cm2 current density due to a Bose-Einstein Condensate at room temperature produced by Focused Electron Beam Induced Processing for many extraordinary novel technical applications

    Science.gov (United States)

    Koops, Hans W. P.

    2015-12-01

    The discovery of Focused Electron Beam Induced Processing and early applications of this technology led to the possible use of a novel nanogranular material “Koops-GranMat®” using Pt/C and Au/C material. which carries at room temperature a current density > 50 times the current density which high TC superconductors can carry. The explanation for the characteristics of this novel material is given. This fact allows producing novel products for many applications using Dual Beam system having a gas supply and X.Y.T stream data programming and not using GDSII layout pattern control software. Novel products are possible for energy transportation. -distribution.-switching, photon-detection above 65 meV energy for very efficient energy harvesting, for bright field emission electron sources used for vacuum electronic devices like amplifiers for HF electronics, micro-tubes, 30 GHz to 6 THz switching amplifiers with signal to noise ratio >10(!), THz power sources up to 1 Watt, in combination with miniaturized vacuum pumps, vacuum gauges, IR to THz detectors, EUV- and X-Ray sources. Since focusing electron beam induced deposition works also at low energy, selfcloning multibeam-production machines for field emitter lamps, displays, multi-beam - lithography, - imaging, and - inspection, energy harvesting, and power distribution with switches controlling field-emitter arrays for KA of currents but with < 100 V switching voltage are possible. Finally the replacement of HTC superconductors and its applications by the Koops-GranMat® having Koops-Pairs at room temperature will allow the investigation devices similar to Josephson Junctions and its applications now called QUIDART (Quantum interference devices at Room Temperature). All these possibilities will support a revolution in the optical, electric, power, and electronic technology.

  18. Towards a Carbon Nanotube Ionization Source for Planetary Atmosphere Exploration

    Science.gov (United States)

    Oza, A. V.; Leblanc, F.; Berthelier, J. J.; Becker, J.; Coulomb, R.; Gilbert, P.; Hong, N. T.; Lee, S.; Vettier, L.

    2015-12-01

    The characterization of planetary exospheres today, relies on the development of a highly efficient ionization source, due to the scant neutral molecules (n atmospheres provide insight on to physical processes known to occur such as: space weathering, magneto-atmosphere interactions, as well as atmospheric escape mechanisms, all of which are being heavily investigated via current 3D Monte Carlo simulations (Turc et al. 2014, Leblanc et al. 2016 in prep) at LATMOS. Validation of these studies will rely on in-situ observations in the coming decades. Neutral detection strongly depends on electron-impact ionization which via conventional cathode-sources, such as thermal filaments (heated up to 2000 K), may only produce the target ionization essential for energy-measurements with large power consumption. Carbon nanotubes (CNTs) however are ideal low-power, cold cathodes, when subject to moderate electric fields (E ~ 1 MV / m). We present our current device, a small CNT chip, of emission area 15 mm2, emitting electrons that pass through an anode grid and subsequent electrostatic analyzer. The device currently extracts hundreds of µAmperes with applied external voltages ~ -150 Volts, approaching minimum power consumption plasma sputtering the icy regolith with heavy ions and electrons (keV < E < MeV), producing predominately molecular oxygen (Johnson et al. 2002).

  19. Structure and density of Callisto's atmosphere from a fluid-kinetic model of its ionosphere: Comparison with Hubble Space Telescope and Galileo observations

    Science.gov (United States)

    Hartkorn, Oliver; Saur, Joachim; Strobel, Darrell F.

    2017-01-01

    We develop a model of the ionospheric electron population of Jupiter's moon Callisto using a prescribed neutral atmosphere composed of O2, CO2 and H2O. A kinetic description of ionospheric suprathermal electrons coupled with a fluid description of ionospheric thermal electrons is well suited to jointly analyze and interpret observations of electron density and atmospheric UV emission. Accordingly, we calculate the electron energy distribution function at each point in the ionosphere by solving a coupled set of equations consisting of the Boltzmann equation for suprathermal electrons and the continuity and energy equation for thermal electrons. We assume a stationary balance between local sources and sinks of electrons and electron energy. Electron transport within the ionosphere is neglected, since collision time scales are shorter than transport time scales in the region of Callisto's ionosphere where the major concentrations of electrons is located and the major part of the atmospheric UV emission is generated. We consider photoionization, which is the dominant ionospheric electron source, and secondary ionization from collisions of photoelectrons with neutrals. Our calculations yield electron densities and electron impact generated UV emissions from Callisto's atmosphere. Comparing our modeled UV emission intensities with the Hubble Space Telescope observation of Cunningham et al. (2015) , we find that Callisto's atmosphere has a mean O2 column density of 2.1-1.1+1.1 ×1019 m-2. A joint comparison with this HST observation and radio occultation observations of Kliore et al. (2002) shows that Callisto's atmosphere possesses a day night asymmetry. We derive terminator O2 column densities of ∼ 0.4 × 1019 m-2 , for which we find subsolar O2 column densities in the range of 2.4 - 9.8 ×1019 m-2. Our calculations also show that the electron density is very sensitive to the relative abundance of H2O due to the thermal electron cooling by rotational state excitation

  20. Studies of suprathermal emission due to cyclotron-electronic heating of the tokamak TCV plasma; Etudes du rayonnement suprathermique emis lors du chauffage cyclotronique electronique du plasma du tokamak TCV

    Energy Technology Data Exchange (ETDEWEB)

    Blanchard, P

    2002-07-01

    Photo sensitization of wide band gap semiconductors is used in a wide range of application like silver halide photography and xerography. The development of a new type of solar cells, based on the sensitization of meso porous metal oxide films by panchromatic dyes, has triggered a lot of fundamental research on electron transfer dynamics. Upon excitation, the sensitizer transfers an electron in the conduction band of the semiconductor. Recombination of the charge separated state is prevented by the fast regeneration of the dye by an electron donor present in solution. Until recently, most of the work in this area has been focused on the competition between the recombination and the regeneration processes, which take place in the nanosecond to millisecond regime. With the development of solid-state femtosecond laser, the measurement of the dynamics of the first electron transfer step occurring in the solar cell has become possible . Electron injection from ruthenium(Il) poly pyridyl complexes into titanium dioxide has been found to occur with a poly exponential rate, with time constants ranging from < 100 fs up to > 10 ps. In spite of the lately acquired capacity to measure the dynamics of these reactions, the physical meaning of this poly exponential kinetics and the factors that can influence this process are still poorly understood. In this work, the development of a new femtosecond pump-probe spectrometer, intended to monitor the ultrafast dynamics of electron injection, is presented. The study of this process requires an excellent temporal resolution and a large wavelength tunability to be able to excite a great variety of dyes and to probe the different products of the reaction. These specifications were met using the latest progress made in optical parametric amplification, which allowed the construction of a versatile experimental set-up. The interfacing by computer of the different devices used during the experiments increase the ease of use of the set

  1. Formation of the high-intensity microsecond flow of electrons in the channel of high pressure arc discharge

    CERN Document Server

    Volkolupov, Yu Ya; Kolyada, Y E; Fedun, V I; Onishchenko, I N

    2000-01-01

    The possibility of microsecond duration powerful electron flows formation in the channel of high current arc discharge at atmosphere pressure has been experimentally demonstrated. The flow of electrons is formed at applying the high voltage pulse to the plasma source after plasma ejection and the pressure decreasing. Because the acceleration by the electric field prevails over the friction force due to collisions the conditions for arising of running electrons are fulfilled.

  2. Research on Electron Density in DC Needle-Plate Corona Discharge at Atmospheric Pressure%直流大气压电晕放电电子密度的光谱研究

    Institute of Scientific and Technical Information of China (English)

    刘志强; 郭威; 刘涛涛; 武文硕; 刘淑敏

    2013-01-01

    Using needle-plate discharge device ,corona discharge experiment was done in the atmosphere .Through photo of spot size of light-emitting area ,the relationship between the voltage and thickness of corona layer was discussed .When the distance between tip and plate is fixed ,the thickness of corona layer increases with the increase in voltage ;when the voltage is fixed ,the thickness of corona layer decreases with the increase in the distance between tip and plate .As spectral intensity of N2 (C3Πu ) (337.1 nm)reflects high energy electron density ,it was measured with emission spectrometry .The results show that high ener-gy electron density is the biggest near the needle tip and the relationship between high energy electron density and voltage is basi-cally linear increasing .Fixing voltage ,high energy electron density decreases with the increase in the distance between tip and plate .When the voltage and the distance between tip and plate are fixed ,the high energy electron density increases with the de-crease in the curvature radius of needle tip .These results are of great importance for the study of plasma parameters of corona discharge .%利用自制针-板式放电装置,在大气中进行电晕放电实验。用发光区域照片光斑的大小,讨论了电晕层厚度与电源电压的关系。在相同针板间距下,电晕层厚度随着电压的升高而增大;在相同电压下,电晕层厚度随着针板间距的增大而减小。由于高能电子密度能够通过氮分子第二正带系337.1 nm的光谱强度大小反映,因此对氮分子第二正带系337.1 nm谱线的强度用发射光谱法进行了测量。实验结果发现在针尖附近高能电子密度最大,并且高能电子密度随电压的升高而增大;电压一定时,高能电子密度随针板间距的增大而减小。在针板间距和电源电压不变的情况下,高能电子密度随针尖曲率半径的减小而增大。

  3. Greening Electronics

    DEFF Research Database (Denmark)

    Pizzol, Massimo; Søes Kokborg, Morten; Thomsen, Marianne

    Based on a literature review with focus on hazardous substances in waste electric and electronic equipment (WEEE) and numbers from a Danish treatment facility a flow analysis for specific substances has been conducted. Further, the accessible knowledge on human and environmental effects due...

  4. Electron Microscopy Characterization of Aerosols Collected at Mauna Loa Observatory During Asian Dust Storm Event

    Science.gov (United States)

    Atmospheric aerosol particles have a significant influence on global climate due to their ability to absorb and scatter incoming solar radiation. Size, composition, and morphology affect a particle’s radiative properties and these can be characterized by electron microscopy. Lo...

  5. Positron production within our atmosphere

    Science.gov (United States)

    Dwyer, Joseph

    2016-04-01

    Positrons are commonly produced within our atmosphere by cosmic rays and the decay radioactive isotopes. Energetic positrons are also produced by pair production from the gamma rays generated by relativistic runaway electrons. Indeed, such positrons have been detected in Terrestrial Electron Beams (TEBs) in the inner magnetosphere by Fermi/GBM. In addition, positrons play an important role in relativistic feedback discharges (also known as dark lightning). Relativistic feedback models suggest that these discharges may be responsible for Terrestrial Gamma-ray Flashes (TGFs) and some gamma-ray glows. When producing TGFs, relativistic feedback discharges may generate large, lightning-like currents with current moments reaching hundreds of kA-km. In addition, relativistic feedback discharges also may limit the electric field that is possible in our atmosphere, affecting other mechanisms for generating runaway electrons. It is interesting that positrons, often thought of as exotic particles, may play an important role in thunderstorm processes. In this presentation, the role of positrons in high-energy atmospheric physics will be discussed. The unusual observation of positron clouds inside a thunderstorm by the ADELE instrument on an NCAR/NSF Gulfstream V aircraft will also be described. These observations illustrate that we still have much to learn about positron production within our atmosphere.

  6. Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

    Science.gov (United States)

    Helling, Ch; Rimmer, P. B.; Rodriguez-Barrera, I. M.; Wood, Kenneth; Robertson, G. B.; Stark, C. R.

    2016-07-01

    Brown dwarfs and giant gas extrasolar planets have cold atmospheres with rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral cloud particles are charged due to triboelectric processes in such dynamic atmospheres. The dynamics of the atmospheric gas is driven by the irradiating host star and/or by the rotation of the objects that changes during its lifetime. Thermal gas ionisation in these ultra-cool but dense atmospheres allows electrostatic interactions and magnetic coupling of a substantial atmosphere volume. Combined with a strong magnetic field \\gg {{B}\\text{Earth}} , a chromosphere and aurorae might form as suggested by radio and x-ray observations of brown dwarfs. Non-equilibrium processes like cosmic ray ionisation and discharge processes in clouds will increase the local pool of free electrons in the gas. Cosmic rays and lighting discharges also alter the composition of the local atmospheric gas such that tracer molecules might be identified. Cosmic rays affect the atmosphere through air showers in a certain volume which was modelled with a 3D Monte Carlo radiative transfer code to be able to visualise their spacial extent. Given a certain degree of thermal ionisation of the atmospheric gas, we suggest that electron attachment to charge mineral cloud particles is too inefficient to cause an electrostatic disruption of the cloud particles. Cloud particles will therefore not be destroyed by Coulomb explosion for the local temperature in the collisional dominated brown dwarf and giant gas planet atmospheres. However, the cloud particles are destroyed electrostatically in regions with strong gas ionisation. The potential size of such cloud holes would, however, be too small and might occur too far inside the cloud to mimic the effect of, e.g. magnetic field induced star spots.

  7. Evolution of the atmosphere.

    Science.gov (United States)

    Nunn, J F

    1998-01-01

    Planetary atmospheres depend fundamentally upon their geochemical inventory, temperature and the ability of their gravitational field to retain gases. In the case of Earth and other inner planets, early outgassing released mainly carbon dioxide and water vapour. The secondary veneer of comets and meteorites added further volatiles. Photodissociation caused secondary changes, including the production of traces of oxygen from water. Earth's gravity cannot retain light gases, including hydrogen. but retains oxygen. Water vapour generally does not pass the cold trap at the stratopause. In the archaean, early evolution of life, probably in hydrothermal vents, and the subsequent development of photosynthesis in surface waters, produced oxygen, at 3500 Ma or even earlier, becoming a significant component of the atmosphere from about 2000 Ma. Thereafter banded iron formations became rare, and iron was deposited in oxidized red beds. Atmospheric levels of carbon dioxide and oxygen have varied during the Phanerozoic: major changes may have caused extinctions. particularly the Permian/Triassic. The declining greenhouse effect due to the long-term decrease in carbon dioxide has largely offset increasing solar luminosity, and changes in carbon dioxide levels relate strongly to cycles of glaciation.

  8. Electron impact excitation of N$^{3+}$ using the B-spline R-matrix method: Limitations due to the target structure description and the size of the close-coupling expansion

    CERN Document Server

    Fernández-Menchero, L; Bartschat, K

    2016-01-01

    There are major discrepancies between recent ICFT (Intermediate Coupling Frame Transformation) and DARC (Dirac Atomic R-matrix Code) calculations (Fern\\'andez-Menchero et al. 2014, Astron. Astroph. 566 A104, Aggarwal et al. 2016 Mon. Not. R Astr. Soc. 461 3997) regarding electron impact excitation rates for transitions in several Be-like ions, as well as claims that DARC calculations are much more accurate and the ICFT results might even be wrong. To resolve possible reasons for these discrepancies and to estimate the accuracy of the various results, we carried out independent B-Spline R-Matrix (BSR) calculations for electron-impact excitation of the Be-like ion N$^{3+}$. Our close-coupling expansions contain the same target states (238 levels overall) as the previous ICFT and DARC calculations, but the representation of the target wave functions is completely different. We find close agreement among all calculations for the strong transitions between low-lying states, whereas there remain serious discrepanci...

  9. The ratio between effective doses due to external exposure to electrons for tomographic and mathematical models; Razoes entre doses efetivas devido a exposicao externa de eletrons para modelos tomograficos e matematicos

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Fernando R.A. [Centro Regional de Ciencias Nucleares (CRCN), Recife, PE (Brazil)]|[Faculdade Boa Viagem (FBV), Recife, PE (Brazil)]. E-mail: falima@cnen.gov.br; Kramer, Richard; Khoury, Helen J. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear]. E-mail: rkramer@uol.com.br; hjkhoury@globo.com; Vieira, Jose W. [Centro Federal de Educacao Tecnologica de Pernambuco (CEFET-PE), Recife, PE (Brazil)]. E-mail: jwvieira@br.inter.net; Yoriyaz, Helio [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: hyotiyaz@ipen.br; Loureiro, Eduardo C.M. [Universidade de Pernambuco, Recife, PE (Brazil). Escola Politecnica (POLI/UPE)]. E-mail: eduloureiro@uol.com.br

    2005-07-01

    The development of new, sophisticated Monte Carlo codes, and of tomographic or voxel based human phantoms motivated the International Commission on Radiological Protection (ICRP) to call for a revision of traditional exposure models, which have been used in the past to calculate organ and tissue as well as effective dose coefficients for stylized MIRD5- type phantoms. This paper reports about calculations made with the recently developed tomographic MAX (Male Adult voXel) and FAX (Female Adult voXel) phantoms, as well as with the gender-specific MIRD5-type phantoms ADAM and EVA, coupled to the EGS4 and to the MCNP4C Monte Carlo code, for external whole-body irradiation with electrons. Effective doses for the tomographic and for the stylized exposure models will be compared separately as function of the replacement of the Monte Carlo code, of human tissue compositions, and of the stylized by the tomographic anatomy. The results indicate that for external exposures to electrons the introduction of voxel-based exposure models causes changes of the effective dose between +40% and - 60% depending on the energies and geometries considered compared to corresponding data of the MIRD5-type phantoms. (author)

  10. Microwave diagnostics of atmospheric plasmas

    Science.gov (United States)

    Scott, David

    Plasma treatment of biological tissues has tremendous potential due to the wide range of applications. Most plasmas have gas temperatures which greatly exceed room temperature. These are often utilized in electro-surgery for cutting and coagulating tissue. Another type of plasma, referred to as cold atmospheric plasma, or CAP, is characterized by heavy particle temperatures which are at or near room temperature. Due to this lack of thermal effect, CAP may provide less invasive medical procedures. Additionally, CAP have been demonstrated to be effective at targeting cancer cells while minimizing damage to the surrounding tissue. A recently fabricated Microwave Electron Density Device (MEDD) utilizes microwave scattering on small atmospheric plasmas to determine the electron plasma density. The MEDD can be utilized on plasmas which range from a fraction of a millimeter to several centimeters at atmospheric pressure when traditional methods cannot be applied. Microwave interferometry fails due to the small size of the plasma relative to the microwave wavelength which leads to diffraction and negligible phase change; electrostatic probes introduce very strong perturbation and are associated with difficulties of application in strongly-collisional atmospheric conditions; and laser Thomson scattering is not sensitive enough to measure plasma densities less than 1012 cm-3. The first part of this dissertation provides an overview of two types of small atmospheric plasma objects namely CAPs and plasmas utilized in the electro-surgery. It then goes on to describe the fabrication, testing and calibration of the MEDD facility. The second part of this dissertation is focused on the application of the MEDD and other diagnostic techniques to both plasma objects. A series of plasma images that illustrate the temporal evolution of a discharge created by an argon electrosurgical device operating in the coagulation mode and its behavior was analyzed. The discharge of the argon

  11. Comment on “A study of vertical and in-plane electron mobility due to interface roughness scattering at low temperature in InAs-GaSb superlattices” [J. Appl. Phys. 114, 053712 (2013)

    Energy Technology Data Exchange (ETDEWEB)

    Szmulowicz, F., E-mail: Frank.Szmulowicz.ctr@wpafb.af.mil [University of Dayton Research Institute, 300 College Park Ave., Dayton, Ohio 45469-0072 (United States)

    2014-04-14

    The purpose of this comment is to point out that the paper by Safa, Asgari, and Faraone [J. Appl. Phys. 114, 053712 (2013)] (SAF) on electronic transport in superlattices contains a number of errors in physics and execution. By dealing with a finite number of periods and forcing the wave function to be zero at the upper and lower boundaries of the superlattice stack, SAF have turned the system into a quantum well for which the momentum along the growth axis is not a good quantum number, so that the bands in the growth direction are flat and the corresponding carrier velocities and vertical mobilities are zero. A number of other errors allow the authors to get nonzero results and to reach conclusions that qualitatively mirror those of Szmulowicz, Haugan, Elhamri, and Brown [Phys. Rev. B 84, 155307 (2011)].

  12. Comment on "A study of vertical and in-plane electron mobility due to interface roughness scattering at low temperature in InAs-GaSb superlattices" [J. Appl. Phys. 114, 053712 (2013)

    Science.gov (United States)

    Szmulowicz, F.

    2014-04-01

    The purpose of this comment is to point out that the paper by Safa, Asgari, and Faraone [J. Appl. Phys. 114, 053712 (2013)] (SAF) on electronic transport in superlattices contains a number of errors in physics and execution. By dealing with a finite number of periods and forcing the wave function to be zero at the upper and lower boundaries of the superlattice stack, SAF have turned the system into a quantum well for which the momentum along the growth axis is not a good quantum number, so that the bands in the growth direction are flat and the corresponding carrier velocities and vertical mobilities are zero. A number of other errors allow the authors to get nonzero results and to reach conclusions that qualitatively mirror those of Szmulowicz, Haugan, Elhamri, and Brown [Phys. Rev. B 84, 155307 (2011)].

  13. Nightside Martian Ionosphere Produced by Electron Impact Ionization

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi-Teng; LI Lei

    2009-01-01

    Based on the Martian magnetic field model established by magnetohydrodynamics simulation,we determine the possible precipitation areas of the solar wind electron in the nightside Martian atmosphere,and analyze the electron impact ionization to estimate the height of the nightside Martian ionospheric peak and the electron density profile using the energy flux analysis method.The influences of the single electron energy,electron energy density and ionization efficiency on the altitude of the ionospheric peak and the electron density profile axe also investigated.Our results show that the solar wind electron moves along the V-shaped solar wind magnetic field lines,to precipitate into the Martian atmosphere.Due to the crustal magnetic field,the precipitation regions on the nightside are quite narrow and unstable.The impact ionization happens at the altitude of 130-500km,and the height of the ionospheric peak is around 170kin,with a peak electron density of 3.0×103 cm-3.The simulation results are consistent with the results from Mars 4/5 and Viking occultation measurements.

  14. Chemistry in the near-surface atmosphere at Ganymede

    Science.gov (United States)

    Shematovich, V. I.

    2013-09-01

    chemistry using the efficient algorithms [1,4,6] of the kinetic Monte Carlo approach. The photochemistry in such neutral gaseous envelopes [1-3] and the radiolytic chemistry in the icy re golith [5] are initiated by the solar UV radiation and solar wind and/or magnetospheric plasma influence. Chemical complexity of the near-surface atmosphere of the icy satellite arises due to both primary processes of dissociation and ionization by solar UV radiation and magnetospheric electrons and induced ion-molecular chemistry, and by chemical exchange between near-surface atmospheric layer and the satellite icy surface due to the thermal and non-thermal desorption processes. Therefore, the standard astrochemical KIDA network was used to follow the main chemical pathways of photochemistry in the near-surface atmosphere and of diffusive chemistry in the icy regolith. Developed model was used to investigate the chemical diversity and complexity in the atmosphere-icy surface interface at Ganymede. This atmosphere is found to be a very tenuous and surface - bounded gaseous envelope with O2 molecules being the main constituent [1-3]. Modelling of the chemistry of atmosphere-icy surface interface, and, especially, ionization chemistry [4], allows us to quantify neutral and iondensities near and exchange fluxes across the atmosphere - surface interface. Because ion composition measurements are far more sensitive, so that even trace species could be measured in the pick-up ion opulations downstream from Ganymede. Results of calculations were compared with the measurements received by the Galileo spacecraft and can be used to support the future missions to the Jovian system. Moreover, theoretical predictions of the composition and chemical evolution of Ganymede's near - surface environment are of great importance for assessing the biological potential of this satellite.

  15. What we can learn from atmospheric neutrinos

    Science.gov (United States)

    Choubey, Sandhya

    2011-12-01

    Physics potential of future measurements of atmospheric neutrinos is explored. Observation of Δm212 driven sub-dominant effects and θ13 driven large matter effects in atmospheric neutrinos can be used to study the deviation of θ23 from maximality and its octant. Neutrino mass hierarchy can be determined extremely well due to the large matter effects. New physics can be constrained both in standard atmospheric neutrino experiments as well as in future neutrino telescopes.

  16. What we can learn from atmospheric neutrinos

    OpenAIRE

    2006-01-01

    Physics potential of future measurements of atmospheric neutrinos is explored. Observation of $\\Delta m^2_{21}$ driven sub-dominant effects and $\\theta_{13}$ driven large matter effects in atmospheric neutrinos can be used to study the deviation of $\\theta_{23}$ from maximality and its octant. Neutrino mass hierarchy can be determined extremely well due to the large matter effects. New physics can be constrained both in standard atmospheric neutrino experiments as well as in future neutrino t...

  17. What we can learn from atmospheric neutrinos

    CERN Document Server

    Choubey, S

    2011-01-01

    Physics potential of future measurements of atmospheric neutrinos is explored. Observation of $\\Delta m^2_{21}$ driven sub-dominant effects and $\\theta_{13}$ driven large matter effects in atmospheric neutrinos can be used to study the deviation of $\\theta_{23}$ from maximality and its octant. Neutrino mass hierarchy can be determined extremely well due to the large matter effects. New physics can be constrained both in standard atmospheric neutrino experiments as well as in future neutrino telescopes.

  18. Waves in vertically inhomogeneous dissipative atmosphere

    CERN Document Server

    Dmitrienko, I S

    2015-01-01

    A method of construction of solution for acoustic-gravity waves (AGW) above a wave source, taking dissipation throughout the atmosphere into account (Dissipative Solution above Source, DSAS), is proposed. The method is to combine three solutions for three parts of the atmosphere: an analytical solution for the upper isothermal part and numerical solutions for the real non-isothermal dissipative atmosphere in the middle part and for the real non-isothermal small dissipation atmosphere in the lower one. In this paper the method has been carried out for the atmosphere with thermal conductivity but without viscosity. The heights of strong dissipation and the total absorption index in the regions of weak and average dissipation are found. For internal gravity waves the results of test calculations for an isothermal atmosphere and calculations for a real non-isothermal atmosphere are shown in graphical form. An algorithm and appropriate code to calculate DSAS, taking dissipation due to finite thermal conductivity i...

  19. Electronics and electronic systems

    CERN Document Server

    Olsen, George H

    1987-01-01

    Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

  20. Due process traditionalism.

    Science.gov (United States)

    Sunstein, Cass R

    2008-06-01

    In important cases, the Supreme Court has limited the scope of "substantive due process" by reference to tradition, but it has yet to explain why it has done so. Due process traditionalism might be defended in several distinctive ways. The most ambitious defense draws on a set of ideas associated with Edmund Burke and Friedrich Hayek, who suggested that traditions have special credentials by virtue of their acceptance by many minds. But this defense runs into three problems. Those who have participated in a tradition may not have accepted any relevant proposition; they might suffer from a systematic bias; and they might have joined a cascade. An alternative defense sees due process traditionalism as a second-best substitute for two preferable alternatives: a purely procedural approach to the Due Process Clause, and an approach that gives legislatures the benefit of every reasonable doubt. But it is not clear that in these domains, the first-best approaches are especially attractive; and even if they are, the second-best may be an unacceptably crude substitute. The most plausible defense of due process traditionalism operates on rule-consequentialist grounds, with the suggestion that even if traditions are not great, they are often good, and judges do best if they defer to traditions rather than attempting to specify the content of "liberty" on their own. But the rule-consequentialist defense depends on controversial and probably false assumptions about the likely goodness of traditions and the institutional incapacities of judges.

  1. FAST TRACK COMMUNICATION: Contrasting characteristics of sub-microsecond pulsed atmospheric air and atmospheric pressure helium-oxygen glow discharges

    Science.gov (United States)

    Walsh, J. L.; Liu, D. X.; Iza, F.; Rong, M. Z.; Kong, M. G.

    2010-01-01

    Glow discharges in air are often considered to be the ultimate low-temperature atmospheric pressure plasmas for numerous chamber-free applications. This is due to the ubiquitous presence of air and the perceived abundance of reactive oxygen and nitrogen species in air plasmas. In this paper, sub-microsecond pulsed atmospheric air plasmas are shown to produce a low concentration of excited oxygen atoms but an abundance of excited nitrogen species, UV photons and ozone molecules. This contrasts sharply with the efficient production of excited oxygen atoms in comparable helium-oxygen discharges. Relevant reaction chemistry analysed with a global model suggests that collisional excitation of O2 by helium metastables is significantly more efficient than electron dissociative excitation of O2, electron excitation of O and ion-ion recombination. These results suggest different practical uses of the two oxygen-containing atmospheric discharges, with air plasmas being well suited for nitrogen and UV based chemistry and He-O2 plasmas for excited atomic oxygen based chemistry.

  2. Atmosphere: Power, Critique, Politics

    DEFF Research Database (Denmark)

    Albertsen, Niels

    2016-01-01

    This paper hans three interrelated parts. First, atmosphere is approached through the concept of power. Atmospheres 'grip' us directly or mediate power indirectly by manipulating moods and evoking emotions. How does atmosphere relate to different conceptions of power? Second, atmospheric powers m...... be critiqued. Which conception of critique can be involved? Third, critiquing atmospheric powers can generate political conflict. How does atmospheric disputes relate to conceptions of politics and the political?...

  3. Energy, atmospheric chemistry, and global climate

    Science.gov (United States)

    Levine, Joel S.

    1991-01-01

    Global atmospheric changes due to ozone destruction and the greenhouse effect are discussed. The work of the Intergovernmental Panel on Climate Change is reviewed, including its judgements regarding global warming and its recommendations for improving predictive capability. The chemistry of ozone destruction and the global atmospheric budget of nitrous oxide are reviewed, and the global sources of nitrous oxide are described.

  4. Onycholysis due to trauma

    Directory of Open Access Journals (Sweden)

    Patricia Chang

    2014-04-01

    Full Text Available Female patient, 35 years old who came to the private office due to discoloration of her left thumbnail and little pain since 1 month ago. Clinical examination shows nail disease on her left thumbnail with onycholysis and dyschromia, dermatoscopy showed white-yellowish discoloration (Fig. 1A, B. The rest of the clinical examination was normal. Patient use to using acrylic nails since 2 years ago and denied some trauma at the nail. The diagnosis of onycholysis due to trauma was done and recommended her not to use acrylic nail, maintain the nail short and avoid wetness.

  5. Atmospheric chemistry: The return of ethane

    Science.gov (United States)

    Hakola, Hannele; Hellén, Heidi

    2016-07-01

    Ethane emissions can lead to ozone pollution. Measurements at 49 sites show that long-declining atmospheric ethane concentrations started rising in 2010 in the Northern Hemisphere, largely due to greater oil and gas production in the USA.

  6. Electrodynamics in Giant Planet Atmospheres

    Science.gov (United States)

    Koskinen, T.; Yelle, R. V.; Lavvas, P.; Cho, J.

    2014-12-01

    The atmospheres of close-in extrasolar giant planets such as HD209458b are strongly ionized by the UV flux of their host stars. We show that photoionization on such planets creates a dayside ionosphere that extends from the thermosphere to the 100 mbar level. The resulting peak electron density near the 1 mbar level is higher than that encountered in any planetary ionosphere of the solar system, and the model conductivity is in fact comparable to the atmospheres of Sun-like stars. As a result, the momentum and energy balance in the upper atmosphere of HD209458b and similar planets can be strongly affected by ion drag and resistive heating arising from wind-driven electrodynamics. Despite much weaker ionization, electrodynamics is nevertheless also important on the giant planets of the solar system. We use a generic framework to constrain the conductivity regimes on close-in extrasolar planets, and compare the results with conductivites based on the same approach for Jupiter and Saturn. By using a generalized Ohm's law and assumed magnetic fields, we then demonstrate the basic effects of wind-driven ion drag in giant planet atmospheres. Our results show that ion drag is often significant in the upper atmosphere where it can also substantially alter the energy budget through resistive heating.

  7. Ambipolar Electric Field, Photoelectrons, and Their Role in Atmospheric Escape From Hot Jupiters

    Science.gov (United States)

    Cohen, O.; Glocer, A.

    2012-01-01

    Atmospheric mass loss from Hot Jupiters can be large due to the close proximity of these planets to their host star and the strong radiation the planetary atmosphere receives. On Earth, a major contribution to the acceleration of atmospheric ions comes from the vertical separation of ions and electrons, and the generation of the ambipolar electric field. This process, known as the "polar wind," is responsible for the transport of ionospheric constituents to Earth's magnetosphere, where they are well observed. The polar wind can also be enhanced by a relatively small fraction of super-thermal electrons (photoelectrons) generated by photoionization.We formulate a simplified calculation of the effect of the ambipolar electric field and the photoelectrons on the ion scale height in a generalized manner. We find that the ion scale height can be increased by a factor of 2-15 due to the polar wind effects. We also estimate a lower limit of an order of magnitude increase of the ion density and the atmospheric mass-loss rate when polar wind effects are included.

  8. Ambipolar Electric Field, Photoelectrons, and their Role in Atmospheric Escape From Hot-jupiters

    CERN Document Server

    Cohen, O

    2012-01-01

    Atmospheric mass-loss from Hot-jupiters can be large due to the close proximity of these planets to their host star and the strong radiation the planetary atmosphere receives. On Earth, a major contribution to the acceleration of atmospheric ions comes from the vertical separation of ions and electrons, and the generation of the ambipolar electric field. This process, known as the "polar wind", is responsible for the transport of ionospheric constituents to the Earth's magnetosphere, where they are well observed. The polar wind can also be enhanced by a relatively small fraction of super-thermal electrons (photoelectrons) generated by photoionization. We formulate a simplified calculation of the effect of the ambipolar electric field and the photoelectrons on the ion scale-height in a generalized manner. We find that the ion scale-height can be increased by a factor of 2-15 due to the polar wind effects. We also estimate a lower limit of an order of magnitude increase of the ion density and the atmospheric ma...

  9. AMBIPOLAR ELECTRIC FIELD, PHOTOELECTRONS, AND THEIR ROLE IN ATMOSPHERIC ESCAPE FROM HOT JUPITERS

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, O. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Glocer, A. [NASA/GSFC, Code 673, Greenbelt, MD 20771 (United States)

    2012-07-01

    Atmospheric mass loss from Hot Jupiters can be large due to the close proximity of these planets to their host star and the strong radiation the planetary atmosphere receives. On Earth, a major contribution to the acceleration of atmospheric ions comes from the vertical separation of ions and electrons, and the generation of the ambipolar electric field. This process, known as the 'polar wind', is responsible for the transport of ionospheric constituents to Earth's magnetosphere, where they are well observed. The polar wind can also be enhanced by a relatively small fraction of super-thermal electrons (photoelectrons) generated by photoionization. We formulate a simplified calculation of the effect of the ambipolar electric field and the photoelectrons on the ion scale height in a generalized manner. We find that the ion scale height can be increased by a factor of 2-15 due to the polar wind effects. We also estimate a lower limit of an order of magnitude increase of the ion density and the atmospheric mass-loss rate when polar wind effects are included.

  10. Atmospheric Research 2014 Technical Highlights

    Science.gov (United States)

    Platnick, Steven

    2015-01-01

    accomplishments during calendar year 2014. The composition of the organization is shown in Figure 1.2 for each code. This report is published in a printed version with an electronic version on our atmospheres Web site, http://atmospheres.gsfc.nasa.gov/.

  11. The global atmospheric loading of dust aerosols

    Science.gov (United States)

    Kok, J. F.; Ridley, D. A.; Haustein, K.; Miller, R. L.; Zhao, C.

    2015-12-01

    Mineral dust is one of the most ubiquitous aerosols in the atmosphere, with important effects on human health and the climate system. But despite its importance, the global atmospheric loading of dust has remained uncertain, with model results spanning about a factor of five. Here we constrain the particle size-resolved atmospheric dust loading and global emission rate, using a novel theoretical framework that uses experimental constraints on the optical properties and size distribution of dust to eliminate climate model errors due to assumed dust properties. We find that most climate models underestimate the global atmospheric loading and emission rate of dust aerosols.

  12. Terrestrial atmosphere, water and astrobiology

    Directory of Open Access Journals (Sweden)

    Coradini M.

    2010-12-01

    Full Text Available Primitive life, defined as a chemical system capable to transfer its molecular information via self-replication and also capable to evolve, originated about 4 billion years ago from the processing of organic molecules by liquid water. Terrestrial atmosphere played a key role in the process by allowing the permanent presence of liquid water and by participating in the production of carbon-based molecules. Water molecules exhibit specific properties mainly due to a dense network of hydrogen bonds. The carbon-based molecules were either home made in the atmosphere and/or in submarine hydrothermal systems or delivered by meteorites and micrometeorites. The search for possible places beyond the earth where the trilogy atmosphere/water/life could exist is the main objective of astrobiology. Within the Solar System, exploration missions are dedicated to Mars, Europa, Titan and the icy bodies. The discovery of several hundreds of extrasolar planets opens the quest to the whole Milky Way.

  13. Credit where due.

    Science.gov (United States)

    Friedman, Steven G

    2016-08-01

    The history of medicine is filled with stories of tireless researchers who failed to get credit for their hard work. Examples of this include Rosalind Franklin, who helped to elucidate the structure of DNA; Frederick Banting, who helped to discover insulin; and Jay McLean, who discovered heparin. The founding of the field of vascular surgery provides one of the most vivid examples of uncredited work. Even though Alexis Carrel was an unpaid, untitled assistant in Charles Guthrie's laboratory, it was Carrel alone who received a Nobel Prize for their work. In an attempt to give credit where due, the reasons for this injustice are described.

  14. Dark-to-arc transition in field emission dominated atmospheric microdischarges

    Energy Technology Data Exchange (ETDEWEB)

    Tholeti, Siva Sashank [School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana 47907 (United States); Semnani, Abbas; Peroulis, Dimitrios [School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Alexeenko, Alina A., E-mail: alexeenk@purdue.edu [School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States)

    2015-08-15

    We study the voltage-current characteristics of gas discharges driven by field emission of electrons at the microscale. Particle-in-cell with Monte Carlo collision calculations are first verified by comparison with breakdown voltage measurements and then used to investigate atmospheric discharges in nitrogen at gaps from 1 to 10 μm. The results indicate the absence of the classical glow discharge regime because field electron emission replaces secondary electron emission as the discharge sustaining mechanism. Additionally, the onset of arcing is significantly delayed due to rarefied effects in electron transport. While field emission reduces the breakdown voltage, the power required to sustain an arc of the same density in microgaps is as much as 30% higher than at macroscale.

  15. Vessel Electronic Reporting System (VERS)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The VERS system is composed of a database and other related applications which facilitate the reporting of electronically collected research data via Fisheries...

  16. NOAA Electronic Navigational Charts (ENC)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of Coast Survey (OCS) has been involved in the development of a NOAA Electronic Navigational Chart (NOAA ENC) suite to support the marine transportation...

  17. Atmospheric neutrinos and discovery of neutrino oscillations.

    Science.gov (United States)

    Kajita, Takaaki

    2010-01-01

    Neutrino oscillation was discovered through studies of neutrinos produced by cosmic-ray interactions in the atmosphere. These neutrinos are called atmospheric neutrinos. They are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron-neutrinos and muon-neutrinos are produced mainly by the decay chain of charged pions to muons to electrons. Atmospheric neutrino experiments observed zenith-angle and energy dependent deficit of muon-neutrino events. Neutrino oscillations between muon-neutrinos and tau-neutrinos explain these data well. Neutrino oscillations imply that neutrinos have small but non-zero masses. The small neutrino masses have profound implications to our understanding of elementary particle physics and the Universe. This article discusses the experimental discovery of neutrino oscillations.

  18. Atmospheric Gaseous Plasma with Large Dimensions

    Science.gov (United States)

    Korenev, Sergey

    2012-10-01

    The forming of atmospheric plasma with large dimensions using electrical discharge typically uses the Dielectric Barrier Discharge (DBD). The study of atmospheric DBD was shown some problems related to homogeneous volume plasma. The volume of this plasma determines by cross section and gas gap between electrode and dielectric. The using of electron beam for volume ionization of air molecules by CW relativistic electron beams was shown the high efficiency of this process [1, 2]. The main advantage of this approach consists in the ionization of gas molecules by electrons in longitudinal direction determines by their kinetic energy. A novel method for forming of atmospheric homogeneous plasma with large volume dimensions using ionization of gas molecules by pulsed non-relativistic electron beams is presented in the paper. The results of computer modeling for delivered doses of electron beams in gases and ionization are discussed. The structure of experimental bench with plasma diagnostics is considered. The preliminary results of forming atmospheric plasma with ionization gas molecules by pulsed nanosecond non-relativistic electron beam are given. The analysis of potential applications for atmospheric volume plasma is presented. Reference: [1] S. Korenev. ``The ionization of air by scanning relativistic high power CW electron beam,'' 2002 IEEE International Conference on Plasma Science. May 2002, Alberta, Canada. [2] S. Korenev, I. Korenev. ``The propagation of high power CW scanning electron beam in air.'' BEAMS 2002: 14th International Conference on High-Power Particle Beams, Albuquerque, New Mexico (USA), June 2002, AIP Conference Proceedings Vol. 650(1), pp. 373-376. December 17.

  19. Atmospheric composition change: Ecosystems-Atmosphere interactions

    NARCIS (Netherlands)

    Fowler, D.; Pilegaard, K.; Sutton, M.A.; Ambus, P.; Raivonen, M.; Duyzer, J.; Simpson, D.; Fagerli, H.; Fuzzi, S.; Schjoerring, J.K.; Granier, C.; Neftel, A.; Isaksen, I.S.A.; Laj, P.; Maione, M.; Monks, P.S.; Burkhardt, J.; Daemmgen, U.; Neirynck, J.; Personne, E.; Wichink Kruit, R.J.; Butterbach-Bahl, K.; Flechard, C.; Tuovinen, J.P.; Coyle, M.; Gerosa, G.; Loubet, B.; Altimir, N.; Gruenhage, L.; Ammann, C.; Cieslik, S.; Paoletti, E.; Mikkelsen, T.N.; Ro-Poulsen, H.; Cellier, P.; Cape, J.N.; Horvath, L.; Loreto, F.; Niinemets, U.; Palmer, P.I.; Rinne, J.; Misztal, P.; Nemitz, E.; Nilsson, D.; Pryor, S.; Gallagher, M.W.; Vesala, T.; Skiba, U.; Brueggemann, N.; Zechmeister-Boltenstern, S.; Williams, J.; O'Dowd, C.; Facchini, M.C.; Leeuw, de G.; Flossman, A.; Chaumerliac, N.; Erisman, J.W.

    2009-01-01

    Ecosystems and the atmosphere: This review describes the state of understanding the processes involved in the exchange of trace gases and aerosols between the earth's surface and the atmosphere. The gases covered include NO, NO2, HONO, HNO3, NH3, SO2, DMS, Biogenic VOC, O-3, CH4, N2O and particles i

  20. Atmospheric escape, redox evolution, and planetary habitability

    Science.gov (United States)

    Catling, D. C.; Zahnle, K. J.

    2011-12-01

    Through the greenhouse effect, the presence and composition of an atmosphere is critical for defining a (conventional) circumstellar habitable zone in terms of planetary surface temperatures suitable for liquid water. Lack of knowledge of planetary atmospheres is likely to frustrate attempts to say with any certainty whether detected terrestrial-sized exoplanets may or may not be habitable. Perhaps an underappreciated role in such considerations is the evolutionary effect of atmospheric escape for determining atmospheric composition or whether an atmosphere exists in the first place. Whether atmospheres exist at all on planets is demonstrably connected to the effect of integrated atmospheric escape. When we observe our own Solar System and transiting exoplanets, the existence of an atmosphere is clearly delineated by a relative vulnerability to thermal escape and impact erosion. The prevalence of thermal escape as a key evolutionary determinant for the presence of planetary atmosphere is shown by a relationship between the relative solar (or stellar) heating and the escape velocity. Those bodies with too much stellar heating and too smaller escape velocity end up devoid of atmospheres. Impact erosion is evident in the relationship between impact velocity and escape velocity. Escape due to impacts is particularly important for understanding the large differences in the atmospheres of giant planet moons, such as Ganymede versus Titan. It is also significant for Mars-sized planets. The oxidation state of atmospheres is important for some theories of the origin of life (where an early reducing atmosphere is helpful for organic synthesis) and the evolution of advanced life (where free molecular oxygen is the best source of high energy metabolism). Surfaces on some relatively small planets and moons are observed to have evolved to an oxidized state, which theory and observation can explain through atmospheric escape. There are several examples in the Solar System where a

  1. Use of electron ionization and atmospheric pressure chemical ionization in gas chromatography coupled to time-of-flight mass spetrometry for screening and identification of organic pollutants in waters

    NARCIS (Netherlands)

    Portoles, T.; Mol, J.G.J.; Sancho, J.V.; Hernandez, F.

    2014-01-01

    A new approach has been developed for multiclass screening of organic contaminants in water based on the use of gas chromatography coupled to hybrid quadrupole high-resolution time-of-flight mass spectrometry with atmospheric pressure chemical ionization (GC–(APCI)QTOF MS). The soft ionization promo

  2. Atmospheric Pressure Plasma Processing for Polymer Adhesion: A Review

    DEFF Research Database (Denmark)

    Kusano, Yukihiro

    2014-01-01

    Atmospheric pressure plasma processing has attracted significant interests over decades due to its usefulness and a variety of applications. Adhesion improvement of polymer surfaces is among the most important applications of atmospheric pressure plasma treatment. Reflecting recent significant...... development of the atmospheric pressure plasma processing, this work presents its fundamental aspects, applications, and characterization techniques relevant to adhesion....

  3. Detection of tracer materials in the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, A.; Lovelock, J.E.

    1981-12-08

    As oxygen is an electron absorber it is desirable, when monitoring an atmospheric flow for the presence of tracer materials capable of detection in an electron capture detector, to remove the oxygen from the flow to the detector. The invention introduces a hydrogen supply directly into the atmospheric flow to allow the hydrogen to combine catalytically with the oxygen content of the flow to form water or water vapor. The thus formed water or water vapor is extracted from the flow proceeding to the detector. The reaction can occur within a palladium or palladium alloy conduit forming a part of the flow path to the detector.

  4. Mirador - Atmospheric Composition

    Data.gov (United States)

    National Aeronautics and Space Administration — Earth Science data access made simple. Atmospheric Composition is focused on the composition of Earth's atmosphere in relation to climate prediction, solar effects,...

  5. Planetary Atmospheric Electricity

    CERN Document Server

    Leblanc, F; Yair, Y; Harrison, R. G; Lebreton, J. P; Blanc, M

    2008-01-01

    This volume presents our contemporary understanding of atmospheric electricity at Earth and in other solar system atmospheres. It is written by experts in terrestrial atmospheric electricity and planetary scientists. Many of the key issues related to planetary atmospheric electricity are discussed. The physics presented in this book includes ionisation processes in planetary atmospheres, charge generation and separation, and a discussion of electromagnetic signatures of atmospheric discharges. The measurement of thunderstorms and lightning, including its effects and hazards, is highlighted by articles on ground and space based instrumentation, and new missions.Theory and modelling of planetary atmospheric electricity complete this review of the research that is undertaken in this exciting field of space science. This book is an essential research tool for space scientists and geoscientists interested in electrical effects in atmospheres and planetary systems. Graduate students and researchers who are new to t...

  6. Our shared atmosphere

    Science.gov (United States)

    Our atmosphere is a precious and fascinating resource, providing air to breath, shielding us from harmful ultraviolet radiation (UV), and maintaining a comfortable climate. Since the industrial revolution, people have significantly altered the composition of the atmosphere throu...

  7. Titan's atmosphere from DISR

    Science.gov (United States)

    West, Robert

    This abstract distills information about Titan's atmosphere described in detail in a paper by M. G. Tomasko, L. Doose, S. Engel, L. E. Dafoe, R. West, M. Lemmon, E. Karkoschka and C. See, ‘A model of Titan's aerosols based on measurements made inside the atmosphere', Planetary and Space Sciences, in press, 2008. The Descent Imager Spectral Radiometer (DISR) observed Titan's sky and surface during the descent of the Huygens Probe in January, 2005. Measurements were made over the altitude range 160 Km to the surface near latitude -10 degrees. The DISR instrument package included several components to measure the radiation state as a function of altitude. These include upward and downward-looking visible and near-infrared spectrometers covering the wavelength range 450 to 1600 nm, an ultraviolet photometer, a solar aureole camera with polarizers, and a sun sensor. Measurements were made at a variety of azimuthal angles relative to the sun azimuth. Due to unanticipated behavior of the probe (reverse spin and high-amplitude, chaotic tip and tilt) the retrieval process has required more effort than was planned and the total science return is less than expected. Nevertheless the data yielded unsurpassed and unique information which constrain the optical and physical properties of the photochemical haze aerosols and condensate particles. The principal findings are (1) between 80 Km and 160 Km the photochemical haze is well mixed with the gas with a scale height of about 65 Km, (2) between 80 Km and the surface the particle optical depth is a linear function of altitude with a break in slope near 30 Km altitude, (3) optical properties of the haze do not depend much on altitude above 80 Km although more recent work by Tomasko and colleagues suggest a gradient in the stratosphere; below 80 Km there are changes in optical behavior which suggest that condensation plays a role, (4) the data confirm previous results which proposed a particle structure of aggregates of small

  8. Atmospheric Chemistry Over Southern Africa

    Science.gov (United States)

    Gatebe, Charles K.; Levy, Robert C.; Thompson, Anne M.

    2011-01-01

    During the southern African dry season, regional haze from mixed industrial pollution, biomass burning aerosol and gases from domestic and grassland fires, and biogenic sources from plants and soils is worsened by a semi-permanent atmosphere gyre over the subcontinent. These factors were a driver of several major international field campaigns in the 1990s and early 2000s, and attracted many scientists to the region. Some researchers were interested in understanding fundamental processes governing chemistry of the atmosphere and interaction with climate change. Others found favorable conditions for evaluating satellite-derived measurements of atmospheric properties and a changing land surface. With that background in mind a workshop on atmospheric chemistry was held in South Africa. Sponsored by the International Commission for Atmospheric Chemistry and Global Pollution (ICACGP; http://www.icacgp.org/), the workshop received generous support from the South African power utility, Eskom, and the Climatology Research Group of the University of the Witwatersrand, Johannesburg, South Africa. The purpose of the workshop was to review some earlier findings as well as more recent findings on southern African climate vulnerability, chemical changes due to urbanization, land-use modification, and how these factors interact. Originally proposed by John Burrows, president of ICACGP, the workshop was the first ICACGP regional workshop to study the interaction of air pollution with global chemical and climate change. Organized locally by the University of the Witwatersrand, the workshop attracted more than 60 delegates from South Africa, Mozambique, Botswana, Zimbabwe, France, Germany, Canada, and the United States. More than 30 presentations were given, exploring both retrospective and prospective aspects of the science. In several talks, attention was focused on southern African chemistry, atmospheric pollution monitoring, and climate processes as they were studied in the field

  9. Archives of Atmospheric Lead Pollution

    Science.gov (United States)

    Weiss, Dominik; Shotyk, William; Kempf, Oliver

    Environmental archives such as peat bogs, sediments, corals, trees, polar ice, plant material from herbarium collections, and human tissue material have greatly helped to assess both ancient and recent atmospheric lead deposition and its sources on a regional and global scale. In Europe detectable atmospheric lead pollution began as early as 6000years ago due to enhanced soil dust and agricultural activities, as studies of peat bogs reveal. Increased lead emissions during ancient Greek and Roman times have been recorded and identified in many long-term archives such as lake sediments in Sweden, ice cores in Greenland, and peat bogs in Spain, Switzerland, the United Kingdom, and the Netherlands. For the period since the Industrial Revolution, other archives such as corals, trees, and herbarium collections provide similar chronologies of atmospheric lead pollution, with periods of enhanced lead deposition occurring at the turn of the century and since 1950. The main sources have been industry, including coal burning, ferrous and nonferrous smelting, and open waste incineration until c.1950 and leaded gasoline use since 1950. The greatest lead emissions to the atmosphere all over Europe occurred between 1950 and 1980 due to traffic exhaust. A marked drop in atmospheric lead fluxes found in most archives since the 1980s has been attributed to the phasing out of leaded gasoline. The isotope ratios of lead in the various archives show qualitatively similar temporal changes, for example, the immediate response to the introduction and phasing out of leaded gasoline. Isotope studies largely confirm source assessments based on lead emission inventories and allow the contributions of various anthropogenic sources to be calculated.

  10. Atmospheric and accelerator neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Yoichiro [Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo Higashi-Mozumi, Kamioka, Hida-City, Gifu 506-1205 (Japan)

    2006-05-15

    Results from the atmospheric neutrino measurements are presented. Evidence for the {nu}{sub {tau}} appearance in the atmospheric neutrino events was shown by statistical methods. The long baseline oscillation experiment using man-made neutrinos has confirmed the atmospheric neutrino oscillation. The future accelerator experiments are briefly discussed.

  11. Atmospheric refraction : a history

    NARCIS (Netherlands)

    Lehn, WH; van der Werf, S

    2005-01-01

    We trace the history of atmospheric refraction from the ancient Greeks up to the time of Kepler. The concept that the atmosphere could refract light entered Western science in the second century B.C. Ptolemy, 300 years later, produced the first clearly defined atmospheric model, containing air of un

  12. A change in the electro-physical properties of narrow-band CdHgTe solid solutions acted upon by a volume discharge induced by an avalanche electron beam in the air at atmospheric pressure

    Science.gov (United States)

    Voitsekhovskii, A. V.; Grigor'ev, D. V.; Korotaev, A. G.; Kokhanenko, A. P.; Tarasenko, V. F.; Shulepov, M. A.

    2012-03-01

    The effect of a nanosecond volume discharge forming in an inhomogeneous electrical field at atmospheric pressure on the CdHgTe (MCT) epitaxial films of the p-type conduction with the hole concentration 2·1016 cm3 and mobility 500 cm2·V-1·s-1 is studied. The measurement of the electrophysical parameters of the MCT specimens upon irradiation shows that a layer exhibiting the n-type conduction is formed in the near-surface region of the epitaxial films. After 600 pulses and more, the thickness and the parameters of the layer are such that the measured field dependence of the Hall coefficient corresponds to the material of the n-type conduction. Analysis of the preliminary results reveals that the foregoing nanosecond volume discharge in the air at atmospheric pressure is promising for modification of electro-physical MCT properties.

  13. Atmospheric Habitable Zones in Y Dwarf Atmospheres

    Science.gov (United States)

    Yates, Jack S.; Palmer, Paul I.; Biller, Beth; Cockell, Charles S.

    2017-02-01

    We use a simple organism lifecycle model to explore the viability of an atmospheric habitable zone (AHZ), with temperatures that could support Earth-centric life, which sits above an environment that does not support life. To illustrate our model, we use a cool Y dwarf atmosphere, such as WISE J085510.83–0714442.5, whose 4.5–5.2 μm spectrum shows absorption features consistent with water vapor and clouds. We allow organisms to adapt to their atmospheric environment (described by temperature, convection, and gravity) by adopting different growth strategies that maximize their chance of survival and proliferation. We assume a constant upward vertical velocity through the AHZ. We found that the organism growth strategy is most sensitive to the magnitude of the atmospheric convection. Stronger convection supports the evolution of more massive organisms. For a purely radiative environment, we find that evolved organisms have a mass that is an order of magnitude smaller than terrestrial microbes, thereby defining a dynamical constraint on the dimensions of life that an AHZ can support. Based on a previously defined statistical approach, we infer that there are of the order of 109 cool Y brown dwarfs in the Milky Way, and likely a few tens of these objects are within 10 pc from Earth. Our work also has implications for exploring life in the atmospheres of temperate gas giants. Consideration of the habitable volumes in planetary atmospheres significantly increases the volume of habitable space in the galaxy.

  14. Monte Carlo Ray Tracing Based Sensitivity Analysis of the Atmospheric and the Ocean Parameters on Top of the Atmosphere Radiance

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2013-01-01

    Full Text Available Monte Carlo Ray Tracing: MCRT based sensitivity analysis of the geophysical parameters (the atmosphere and the ocean on Top of the Atmosphere: TOA radiance in visible to near infrared wavelength regions is conducted. As the results, it is confirmed that the influence due to the atmosphere is greater than that of the ocean. Scattering and absorption due to aerosol particles and molecules in the atmosphere is major contribution followed by water vapor and ozone while scattering due to suspended solid is dominant contribution for the ocean parameters.

  15. Possible atmospheric research with Aristoteles

    Science.gov (United States)

    Barlier, Francois

    1991-12-01

    Use of the Aristoteles mission in measuring atmospheric parameters is discussed. The total density of the thermosphere, the temperature of the stratosphere and the total electron count of the ionosphere are identified as three areas in which the Aristoteles mission could be of great use in carrying out research. Combining the accelerometer measurements yields the gravity tensor as well as the nongravitational acceleration acting upon the satellite. Ways in which the temperature of the stratosphere around the Earth, and the annual, seasonal and secular variations it goes through could be measured are discussed.

  16. Would be the Atmosphere Chaotic?

    Directory of Open Access Journals (Sweden)

    Isimar de Azevedo Santos

    2013-07-01

    Full Text Available The atmosphere has often been considered “chaotic” when in fact the “chaos” is a manifestation of the models that simulate it, which do not include all the physical mechanisms that exist within it. A weather prediction cannot be perfectly verified after a few days of integration due to the inherent nonlinearity of the equations of the hydrodynamic models. The innovative ideas of Lorenz led to the use of the ensemble forecast, with clear improvements in the quality of the numerical weather prediction. The present study addresses the statement that “even with perfect models and perfect observations, the ‘chaotic’ nature of the atmosphere would impose a finite limit of about two weeks to the predictability of the weather” as the atmosphere is not necessarily “chaotic”, but the models used in the simulation of atmospheric processes are. We conclude, therefore, that potential exists for developments to increase the horizon of numerical weather prediction, starting with better models and observations.

  17. Atmospheric chemistry in volcanic plumes.

    Science.gov (United States)

    von Glasow, Roland

    2010-04-13

    Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis.

  18. Satellite Anomalies Due to Environment

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These events range from minor operational problems to permanent spacecraft failures. Australia, Canada, Germany, India, Japan, United Kingdom, and the United States...

  19. Neutral atmosphere near the icy surface of Jupiter's moon Ganymede

    Science.gov (United States)

    Shematovich, V. I.

    2016-07-01

    The paper discusses the formation and dynamics of the rarefied gas envelope near the icy surface of Jupiter's moon Ganymede. Being the most massive icy moon, Ganymede can form a rarefied exosphere with a relatively dense near-surface layer. The main parent component of the gas shell is water vapor, which enters the atmosphere due to thermal degassing, nonthermal radiolysis, and other active processes and phenomena on the moon's icy surface. A numerical kinetic simulation is performed to investigate, at the molecular level, the formation, chemical evolution, and dynamics of the mainly H2O- and O2-dominant rarefied gas envelopes. The ionization processes in these rarefied gas envelopes are due to exposure to ultraviolet radiation from the Sun and the magnetospheric plasma. The chemical diversity of the icy moon's gas envelope is attributed to the primary action of ultraviolet solar photons and plasma electrons on the rarefied gas in the H2O- or O2-dominant atmosphere. The model is used to calculate the formation and development of the chemical diversity in the relatively dense near-surface envelope of Ganymede, where an important contribution comes from collisions between parent molecules and the products of their photolysis and radiolysis.

  20. Hard electronics; Hard electronics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    In the fields of power conversion devices and broadcasting/communication amplifiers, high power, high frequency and low losses are desirable. Further, for electronic elements in aerospace/aeronautical/geothermal surveys, etc., heat resistance to 500degC is required. Devices which respond to such hard specifications are called hard electronic devices. However, with Si which is at the core of the present electronics, the specifications cannot fully be fulfilled because of the restrictions arising from physical values. Accordingly, taking up new device materials/structures necessary to construct hard electronics, technologies to develop these to a level of IC were examined and studied. They are a technology to make devices/IC of new semiconductors such as SiC, diamond, etc. which can handle higher temperature, higher power and higher frequency than Si and also is possible of reducing losses, a technology to make devices of hard semiconducter materials such as a vacuum microelectronics technology using ultra-micro/high-luminance electronic emitter using negative electron affinity which diamond, etc. have, a technology to make devices of oxides which have various electric properties, etc. 321 refs., 194 figs., 8 tabs.

  1. What we can learn from atmospheric neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Choubey, Sandhya, E-mail: sandhya@mri.ernet.in [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India)

    2011-12-15

    Physics potential of future measurements of atmospheric neutrinos is explored. Observation of {Delta}m{sub 21}{sup 2} driven sub-dominant effects and {theta}{sub 13} driven large matter effects in atmospheric neutrinos can be used to study the deviation of {theta}{sub 23} from maximality and its octant. Neutrino mass hierarchy can be determined extremely well due to the large matter effects. New physics can be constrained both in standard atmospheric neutrino experiments as well as in future neutrino telescopes.

  2. Electron holes in inhomogeneous magnetic field: electron heating and electron hole evolution

    Science.gov (United States)

    Vasko, Ivan; Agapitov, Oleksiy; Mozer, Forrest; Artemyev, Anton; Drake, James

    2016-04-01

    Electron holes are electrostatic non-linear structures widely observed in the space plasma, e.g., in reconnecting current sheets, collisionless bow shocks, Earth auroral region and outer radiation belt etc. In the present paper we analyze the process of energy exchange between trapped electrons, untrapped electrons and electron hole propagating in weakly inhomogeneous magnetic field. We show that as electron hole propagates into the region with stronger magnetic field, trapped electrons are heated due to conservation of the first adiabatic invariant. At the same time electron hole may grow or dissipate in dependence on peculiarities of distribution functions of trapped and resonant untrapped electrons. The energy gain of trapped electrons is due to energy losses of resonant electrons and/or decrease of electron hole energy (electrostatic energy and kinetic energy of non-resonant electrons). We stress that taking into account the energy exchange with resonant untrapped electrons increases the heating factor of trapped electrons that is proportional to the magnetic field magnitude in the region up to what electron holes survive. We illustrate the suggested mechanism for H. Schamel's electron holes and show that during propagation along a positive magnetic field gradient their amplitude should grow. Neglect of energy exchange with resonant untrapped electrons would result electron hole dissipation with only modest heating factor of trapped electrons. We argue that the suggested mechanism may be responsible for generation of energetic electrons in the space plasma.

  3. Electronic Cigarettes

    Science.gov (United States)

    ... New FDA Regulations Text Size: A A A Electronic Cigarettes Electronic cigarettes (e-cigarettes) are battery operated products designed ... more about: The latest news and events about electronic cigarettes on this FDA page Electronic cigarette basics ...

  4. Effects of nitrogen application and elevated atmospheric CO2 on electron transport and energy partitioning in flag leaf photosynthesis of wheat%施氮和大气CO2浓度升高对小麦旗叶光合电子传递和分配的影响

    Institute of Scientific and Technical Information of China (English)

    张绪成; 于显枫; 马一凡

    2011-01-01

    Wheat ( Triticum aestivum) plants were pot-cultured in open top chambers at the nitrogen application rate of 0 and 200 mg · kg-1 soil and the atmospheric CO2 concentration of 400 and 760 μmol · mol-1. Through the determination of flag leaf nitrogen and chlorophyll contents, photosynthetic rate (Pn)-intercellar CO2 concentration (Ci) response curve, and chlorophyll fluorescence parameters at heading stage, the photosynthetic electron transport rate and others were calculated,aimed to investigate the effects of nitrogen application and elevated atmospheric CO2 concentration on the photosynthetic energy partitioning in wheat flag leaves. Elevated atmospheric CO2 concentration decreased the leaf nitrogen and chlorophyll contents, compared with the ambient one, and the chlorophyll a/b ratio increased at the nitrogen application rate of 200 mg · kg-1. With the application of nitrogen, no evident variations were observed in the maximal photochemical efficiency (Fv/Fm) , maximal quantum yield under irradiance (Fv'/Fm') of PS Ⅱ reaction center, photochemical fluorescence quenching coefficient (qp), and actual PS Ⅱ efficiency under irradiance (ΦPSⅡ) at elevated atmospheric CO2 concentration, and the total photosynthetic electron transport rate ( JF ) of PS Ⅱ reaction center had no evident increase, though the non-photochemical fluorescence quenching coefficient (NPQ ) decreased significantly. With no nitrogen application, the Fv'/ Fm', ΦPSⅡ , and NPQ) at elevated atmospheric CO2 concentration decreased significantly, and the JF had a significant decrease though the Fv/Fm and qp did not vary remarkably. Nitrogen application increased the JF and photochemical electron transport rate (JC); while elevated atmospheric CO2 concentration decreased the photorespiration electron transport rate (J0) , Rubisco oxidation rate ( V0 ), ratio of photorespiration to photochemical electron transport rate ( J0/JC ), and Rubisco oxidation/carboxylation rate ( V0/VC ), but

  5. The impact of energetic electron precipitation on mesospheric hydroxyl during a year of solar minimum

    Science.gov (United States)

    Zawedde, Annet Eva; Nesse Tyssøy, Hilde; Hibbins, Robert; Espy, Patrick J.; Ødegaard, Linn-Kristine Glesnes; Sandanger, Marit Irene; Stadsnes, Johan

    2016-06-01

    In 2008 a sequence of geomagnetic storms occurred triggered by high-speed solar wind streams from coronal holes. Improved estimates of precipitating fluxes of energetic electrons are derived from measurements on board the NOAA/POES 18 satellite using a new analysis technique. These fluxes are used to quantify the direct impact of energetic electron precipitation (EEP) during solar minimum on middle atmospheric hydroxyl (OH) measured from the Aura satellite. During winter, localized longitudinal density enhancements in the OH are observed over northern Russia and North America at corrected geomagnetic latitudes poleward of 55°. Although the northern Russia OH enhancement is closely associated with increased EEP at these longitudes, the strength and location of the North America enhancement appear to be unrelated to EEP. This OH density enhancement is likely due to vertical motion induced by atmospheric wave dynamics that transports air rich in atomic oxygen and atomic hydrogen downward into the middle atmosphere, where it plays a role in the formation of OH. In the Southern Hemisphere, localized enhancements of the OH density over West Antarctica can be explained by a combination of enhanced EEP due to the local minimum in Earth's magnetic field strength and atmospheric dynamics. Our findings suggest that even during solar minimum, there is substantial EEP-driven OH production. However, to quantify this effect, a detailed knowledge of where and when the precipitation occurs is required in the context of the background atmospheric dynamics.

  6. The energy spectrum of cosmic-ray electrons measured with H.E.S.S.

    Energy Technology Data Exchange (ETDEWEB)

    Egberts, Kathrin

    2009-03-30

    The spectrum of cosmic-ray electrons has so far been measured using balloon and satellite-based instruments. At TeV energies, however, the sensitivity of such instruments is very limited due to the low flux of electrons at very high energies and small detection areas of balloon/satellite based experiments. The very large collection area of ground-based imaging atmospheric Cherenkov telescopes gives them a substantial advantage over balloon/ satellite based instruments when detecting very-high-energy electrons (> 300 GeV). By analysing data taken by the High Energy Stereoscopic System (H.E.S.S.), this work extends the known electron spectrum up to 4 TeV - a range that is not accessible to direct measurements. However, in contrast to direct measurements, imaging atmospheric Cherenkov telescopes such as H.E.S.S. detect air showers that cosmic-ray electrons initiate in the atmosphere rather than the primary particle. Thus, the main challenge is to differentiate between air showers initiated by electrons and those initiated by the hadronic background. A new analysis technique was developed that determines the background with the support of the machine-learning algorithm Random Forest. It is shown that this analysis technique can also be applied in other areas such as the analysis of diffuse {gamma} rays from the Galactic plane. (orig.)

  7. The Electron

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, George

    1972-01-01

    Electrons are elementary particles of atoms that revolve around and outside the nucleus and have a negative charge. This booklet discusses how electrons relate to electricity, some applications of electrons, electrons as waves, electrons in atoms and solids, the electron microscope, among other things.

  8. Simulating super earth atmospheres in the laboratory

    Science.gov (United States)

    Claudi, R.; Erculiani, M. S.; Galletta, G.; Billi, D.; Pace, E.; Schierano, D.; Giro, E.; D'Alessandro, M.

    2016-01-01

    Several space missions, such as JWST, TESS and the very recently proposed ARIEL, or ground-based experiments, as SPHERE and GPI, have been proposed to measure the atmospheric transmission, reflection and emission spectra of extrasolar planets. The planet atmosphere characteristics and possible biosignatures will be inferred by studying planetary spectra in order to identify the emission/absorption lines/bands from atmospheric molecules such as water (H2O), carbon monoxide (CO), methane (CH4), ammonia (NH3), etc. In particular, it is important to know in detail the optical characteristics of gases in the typical physical conditions of the planetary atmospheres and how these characteristics could be affected by radiation driven photochemical and biochemical reaction. The main aim of the project `Atmosphere in a Test Tube' is to provide insights on exoplanet atmosphere modification due to biological intervention. This can be achieved simulating planetary atmosphere at different pressure and temperature conditions under the effects of radiation sources, used as proxies of different bands of the stellar emission. We are tackling the characterization of extrasolar planet atmospheres by mean of innovative laboratory experiments described in this paper. The experiments are intended to reproduce the conditions on warm earths and super earths hosted by low-mass M dwarfs primaries with the aim to understand if a cyanobacteria population hosted on a Earth-like planet orbiting an M0 star is able to maintain its photosynthetic activity and produce traceable signatures.

  9. Hard electronics; Hard electronics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Hard material technologies were surveyed to establish the hard electronic technology which offers superior characteristics under hard operational or environmental conditions as compared with conventional Si devices. The following technologies were separately surveyed: (1) The device and integration technologies of wide gap hard semiconductors such as SiC, diamond and nitride, (2) The technology of hard semiconductor devices for vacuum micro- electronics technology, and (3) The technology of hard new material devices for oxides. The formation technology of oxide thin films made remarkable progress after discovery of oxide superconductor materials, resulting in development of an atomic layer growth method and mist deposition method. This leading research is expected to solve such issues difficult to be easily realized by current Si technology as high-power, high-frequency and low-loss devices in power electronics, high temperature-proof and radiation-proof devices in ultimate electronics, and high-speed and dense- integrated devices in information electronics. 432 refs., 136 figs., 15 tabs.

  10. Electron transport coefficients in the mixtures of H2O with N2, O2, CO2 and dry air for the optimization of non-thermal atmospheric pressure plasmas

    Science.gov (United States)

    Ruíz-Vargas, G.; Yousfi, M.; de Urquijo, J.

    2010-11-01

    This paper presents the simultaneous measurement and calculation of the electron drift velocity in binary and ternary mixtures of N2, O2, CO2 with H2O. The main aim of this study has been the generation of a self-consistent set of validated collision cross sections that explain thoroughly the dependence of the electron drift velocity in the above pure gases and their mixtures. In doing this, changes to the collision cross section set for H2O had to be made, while all other cross section sets remained unchanged. It is worth mentioning that only a few experiments had been performed before dealing with water mixtures. The electron drift velocities in the binary and ternary mixtures under study show the effects of negative differential conductivity, and this has been explained thoroughly in terms of the collision cross sections and electron distribution functions through a multi-term Boltzmann code. It is important to note that two-term codes fail to predict the dependence of the drift velocity at low water concentrations and low E/N values. Calculated values of longitudinal and transverse diffusion coefficients, mean energies and distribution functions are also given over the E/N range 0.1 Td-2 kTd (1 Td = 10-17 V cm2).

  11. Electron scattering experiments

    Science.gov (United States)

    Heisenberg, J.

    1984-11-01

    Because of the elementary structure of the electron, it is considered a precise probe of the constituent nature of hadronic matter. Use of the electron as a probe of subnucleonic degrees of freedom in nuclei is discussed in this presentation. Experimentally determined charge distributions for a wide variety of nuclei are presented and compared with shell model calculations which include single particle modes, core polarization, corrections due to delta-hole components, and corrections due to inclusion of meson exchange currents. (AIP)

  12. Atmospheric pollution in power industry under the electronic instrument data how to prevention and control measures%电力工业中大气污染在电子仪器数据下如何防治措施

    Institute of Scientific and Technical Information of China (English)

    常睿; 刘知远

    2016-01-01

    大气污染指对生物有危害的物质在环境中增多,并存在一定时间从而对环境中的生物产生消极影响的现象.火力发电是我国主要的大气污染物排放工业,本文通过对电力工业中大气污染的来源、污染现状的分析,提出电力工业中大气污染的防治措施.%Air pollution,it is the increase in the number of substances in the environment of biological harm,and there is a certain time and negative influence on environment in the biological phenomenon. Thermal power is the main industrial pollutants emission in our country,this article through to the source of atmospheric pollution in power industry,pollution status quo analysis,put forward the control measures of atmospheric pollution in power industry.

  13. Atmospheric Habitable Zones in Y Dwarf Atmospheres

    CERN Document Server

    Yates, Jack S; Biller, Beth; Cockell, Charles S

    2016-01-01

    We use a simple organism lifecycle model to explore the viability of an atmospheric habitable zone (AHZ), with temperatures that could support Earth-centric life, which sits above an environment that does not support life. We illustrate this idea using the object WISE J085510.83-0714442.5, which is a cool, free-floating brown dwarf. We allow organisms to adapt to their atmospheric environment (described by temperature, convection, and gravity) by adopting different growth strategies that maximize their chance of survival and proliferation. We assume a constant upward vertical velocity through the AHZ. We found that the organism growth strategy is most sensitive to the magnitude of the atmospheric convection. Stronger convection supports the evolution of more massive organisms. For a purely radiative environment we find that evolved organisms have a mass that is an order of magnitude smaller than terrestrial microbes, thereby defining a dynamical constraint on the dimensions of life that an AHZ can support. Ba...

  14. Atmospheric Circulation of Exoplanets

    CERN Document Server

    Showman, Adam P; Menou, Kristen

    2009-01-01

    We survey the basic principles of atmospheric dynamics relevant to explaining existing and future observations of exoplanets, both gas giant and terrestrial. Given the paucity of data on exoplanet atmospheres, our approach is to emphasize fundamental principles and insights gained from Solar-System studies that are likely to be generalizable to exoplanets. We begin by presenting the hierarchy of basic equations used in atmospheric dynamics, including the Navier-Stokes, primitive, shallow-water, and two-dimensional nondivergent models. We then survey key concepts in atmospheric dynamics, including the importance of planetary rotation, the concept of balance, and scaling arguments to show how turbulent interactions generally produce large-scale east-west banding on rotating planets. We next turn to issues specific to giant planets, including their expected interior and atmospheric thermal structures, the implications for their wind patterns, and mechanisms to pump their east-west jets. Hot Jupiter atmospheric d...

  15. Structural and molecular basis of the peroxynitrite-mediated nitration and inactivation of Trypanosoma cruzi iron-superoxide dismutases (Fe-SODs) A and B: disparate susceptibilities due to the repair of Tyr35 radical by Cys83 in Fe-SODB through intramolecular electron transfer.

    Science.gov (United States)

    Martinez, Alejandra; Peluffo, Gonzalo; Petruk, Ariel A; Hugo, Martín; Piñeyro, Dolores; Demicheli, Verónica; Moreno, Diego M; Lima, Analía; Batthyány, Carlos; Durán, Rosario; Robello, Carlos; Martí, Marcelo A; Larrieux, Nicole; Buschiazzo, Alejandro; Trujillo, Madia; Radi, Rafael; Piacenza, Lucía

    2014-05-02

    Trypanosoma cruzi, the causative agent of Chagas disease, contains exclusively iron-dependent superoxide dismutases (Fe-SODs) located in different subcellular compartments. Peroxynitrite, a key cytotoxic and oxidizing effector biomolecule, reacted with T. cruzi mitochondrial (Fe-SODA) and cytosolic (Fe-SODB) SODs with second order rate constants of 4.6 ± 0.2 × 10(4) M(-1) s(-1) and 4.3 ± 0.4 × 10(4) M(-1) s(-1) at pH 7.4 and 37 °C, respectively. Both isoforms are dose-dependently nitrated and inactivated by peroxynitrite. Susceptibility of T. cruzi Fe-SODA toward peroxynitrite was similar to that reported previously for Escherichia coli Mn- and Fe-SODs and mammalian Mn-SOD, whereas Fe-SODB was exceptionally resistant to oxidant-mediated inactivation. We report mass spectrometry analysis indicating that peroxynitrite-mediated inactivation of T. cruzi Fe-SODs is due to the site-specific nitration of the critical and universally conserved Tyr(35). Searching for structural differences, the crystal structure of Fe-SODA was solved at 2.2 Å resolution. Structural analysis comparing both Fe-SOD isoforms reveals differences in key cysteines and tryptophan residues. Thiol alkylation of Fe-SODB cysteines made the enzyme more susceptible to peroxynitrite. In particular, Cys(83) mutation (C83S, absent in Fe-SODA) increased the Fe-SODB sensitivity toward peroxynitrite. Molecular dynamics, electron paramagnetic resonance, and immunospin trapping analysis revealed that Cys(83) present in Fe-SODB acts as an electron donor that repairs Tyr(35) radical via intramolecular electron transfer, preventing peroxynitrite-dependent nitration and consequent inactivation of Fe-SODB. Parasites exposed to exogenous or endogenous sources of peroxynitrite resulted in nitration and inactivation of Fe-SODA but not Fe-SODB, suggesting that these enzymes play distinctive biological roles during parasite infection of mammalian cells.

  16. Measurement of atmospheric neutrino oscillations and matter effects with PINGU

    Energy Technology Data Exchange (ETDEWEB)

    Coenders, Stefan; Euler, Sebastian; Krings, Kai; Vehring, Markus; Wallraff, Marius; Wiebusch, Christopher [RWTH Aachen Univ. (Germany). III. Physikalisches Inst.; Collaboration: IceCube-Collaboration

    2013-07-01

    With IceCube's low-energy extension DeepCore the first significant effects of atmospheric neutrino oscillations have been observed. The planned ''Precision Icecube Next Generation Upgrade'' (PINGU) inside DeepCore will lower the energy threshold to a few GeV, where matter effects of neutrino oscillations have to be taken into account. The Mikheyev-Smirnov-Wolfenstein (MSW) effect modifies the mixing between flavor and mass eigenstates of the neutrinos, resulting in stronger oscillations. Furthermore, neutrinos when passing through the Earth core experience parametric enhancement due to multiple discontinuities in the electron density. In this talk the effects of matter oscillations and the capabilities to measure these effects with PINGU are investigated.

  17. MARCS model atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Plez, B [GRAAL, CNRS, UMR5024, Universite Montpellier 2, F-34095 Montpellier, Cedex 5 (France) and Department of Physics and Astronomy, Uppsala University, SE-75120 Uppsala (Sweden)], E-mail: bertrand.plez@graal.univ-montp2.fr

    2008-12-15

    In this review presented at the Symposium A Stellar Journey in Uppsala, June 2008, I give an account of the historical development of the MARCS code, and its premises from the first version published in 1975 to the 2008 grid. The primary driver for the development team who constantly strive to include the best possible physical data, is the science that can be done with the models. A few preliminary comparisons of M star model spectra to spectrophotometric observations are presented. Particular results related to opacity effects are discussed. The size of errors in spectral energy distribution (SED) and model thermal stratification is estimated for different densities of wavelength sampling. The number of points used in the MARCS 2008 grid (108 000) is large enough to ensure errors of only a few K in all models of the grid, except the optically very thin layers of metal-poor stars. Errors in SEDs may reach about 10% locally in the UV. The published sampled SEDs are thus adequate to compute synthetic broadband photometry, but higher resolution spectra will be computed in the near future and published as well on the MARCS site (marcs.astro.uu.se). Test model calculations with TiO line opacity accounted for in scattering show significant cooling of the upper atmospheric layers of red giants. Rough estimates of radiative and collisional time scales for electronic transitions of TiO indicate that scattering may well be the dominant mechanism in these lines. However, models constructed with this hypothesis are incompatible with optical observations of TiO (Arcturus) or IR observations of OH (Betelgeuse), although they may succeed in explaining H{sub 2}O line observations. More work is needed in that direction.

  18. Atmospheric Measurements Laboratory (AML)

    Data.gov (United States)

    Federal Laboratory Consortium — The Atmospheric Measurements Laboratory (AML) is one of the nation's leading research facilities for understanding aerosols, clouds, and their interactions. The AML...

  19. Erosion behaviour of composite Al-Cr cathodes in cathodic arc plasmas in inert and reactive atmospheres

    CERN Document Server

    Franz, Robert; Hawranek, Gerhard; Polcik, Peter

    2015-01-01

    Al$_{x}$Cr$_{1-x}$ composite cathodes with Al contents of x = 0.75, 0.5 and 0.25 were exposed to cathodic arc plasmas in Ar, N$_2$ and O$_2$ atmospheres and their erosion behaviour was studied. Cross-sectional analysis of the elemental distribution of the near-surface zone in the cathodes by scanning electron microscopy revealed the formation of a modified layer for all cathodes and atmospheres. Due to intermixing of Al and Cr in the heat-affected zone, intermetallic Al-Cr phases formed as evidenced by X-ray diffraction analysis. Cathode poisoning effects in the reactive N$_2$ and O$_2$ atmospheres were non-uniform as a result of the applied magnetic field configuration. With the exception of oxide islands on Al-rich cathodes, reactive layers were absent in the circular erosion zone, while nitrides and oxides formed in the less eroded centre region of the cathodes.

  20. Models of magnetized neutron star atmospheres: thin atmospheres and partially ionized hydrogen atmospheres with vacuum polarization

    CERN Document Server

    Suleimanov, V F; Werner, K

    2009-01-01

    Observed X-ray spectra of some isolated magnetized neutron stars display absorption features, sometimes interpreted as ion cyclotron lines. Modeling the observed spectra is necessary to check this hypothesis and to evaluate neutron star parameters.We develop a computer code for modeling magnetized neutron star atmospheres in a wide range of magnetic fields (10^{12} - 10^{15} G) and effective temperatures (3 \\times 10^5 - 10^7 K). Using this code, we study the possibilities to explain the soft X-ray spectra of isolated neutron stars by different atmosphere models. The atmosphere is assumed to consist either of fully ionized electron-ion plasmas or of partially ionized hydrogen. Vacuum resonance and partial mode conversion are taken into account. Any inclination of the magnetic field relative to the stellar surface is allowed. We use modern opacities of fully or partially ionized plasmas in strong magnetic fields and solve the coupled radiative transfer equations for the normal electromagnetic modes in the plas...

  1. CHARACTERIZATION OF ATMOSPHERIC AEROSOL:SINGLE PARTICLE ANALYSIS WITH SCANNING ELECTRON MICROSCOPE%用扫描电镜分析表征大气气溶胶单颗粒

    Institute of Scientific and Technical Information of China (English)

    刘咸德; 董树屏; 李玉武; FreddyAdams

    2003-01-01

    Scanning electron microscope-energy dispersive X-ray analysis system (SEM-EDX) is able to provide analytical data for each single particle. Hundreds of particles are usually analyzed for an aerosol sample. Both physical and chemical characterization can be performed in terms of particle size and particle class compositional data, respectively. Mineral dusts such as aluminosilicates and quartz particles as well as sea salt particles featured coarse fractions. Fine fractions were dominated by various sulfur-containing and carbonaceous particles.

  2. Franklin Lecture: Lightning in Planetary Atmospheres

    Science.gov (United States)

    Gurnett, D. A.

    2006-12-01

    A broad overview is given of lightning in planetary atmospheres. Searches for lightning using spacecraft-borne instrumentation have now been conducted at almost all of the planets in the solar system, the exceptions being Mercury, which has no appreciable atmosphere, and Pluto which has not yet been visited by a spacecraft. The techniques used include (1) imaging observations to detect optical flashes produced by lightning; (2) high-frequency radio measurements to detect the impulsive broadband radio bursts, called spherics, produced by lightning discharges; and (3) low-frequency plasma wave measurements to detect the whistling tones, called whistlers, produced by lightning. Using these techniques, lightning has been reported at five planets other than Earth. These are: Venus, Jupiter, Saturn, Uranus, and Neptune. Of these, the existence of lightning at Venus is doubtful, and the evidence of lightning at Neptune is at best marginal. Jupiter and Saturn have by far the most intense and well documented lightning activity. During the Voyager 1 flyby of Jupiter, whistlers and intense optical flashes, comparable to those from terrestrial superbolts, were observed by the plasma wave and optical imaging instruments. However, no impulsive high-frequency radio bursts were observed. Two factors may be responsible for the absence of high-frequency radio signals: (1) the very strong magnetic field of Jupiter, which blocks the escape of the extra-ordinary mode; and (2) the relatively high electron collision frequency in the ionosphere, which increases the absorption of radio waves. During the Voyager 1 and 2 flybys of Saturn many very strong high-frequency radio bursts, called Saturn Electrostatic Discharges (SEDs), were detected. Although the origin of these impulsive radio bursts was initially uncertain, strong evidence now exists that SEDs are produced by lightning. Recent optical imaging and radio measurements from the Cassini spacecraft clearly show that SEDs originate from

  3. Atmospheric air-plasma treatment of polyester fiber to improve the performance of nanoemulsion silicone

    Energy Technology Data Exchange (ETDEWEB)

    Parvinzadeh, Mazeyar, E-mail: mparvinzadeh@gmail.com [Department of Textile, Islamic Azad University, Shahre Rey Branch, Tehran (Iran, Islamic Republic of); Ebrahimi, Izadyar [Young Researchers Club, Islamic Azad University, Shahre Rey Branch, Tehran (Iran, Islamic Republic of)

    2011-02-15

    Influence of atmospheric air plasma treatment on performance of nanoemulsion silicone softener on polyethylene terephthalate fibers was investigated by the use of fourier transform infrared spectroscopy (FTIR), bending lengths (BL), wrinkle recovery angles (WRA), fiber friction coefficient analysis (FFCA), moisture absorbency (MA), scanning electron microscopy (SEM) and reflectance spectroscopy (RS). Results indicated that the plasma pretreatment modifies the surface of fibers and increases the reactivity of substrate toward nanoemulsion silicone. Moisture regain and microscopic tests showed that the combination of plasma and silicone treatments on polyethylene terephthalate can decrease moisture absorption due to uniform coating of silicone emulsion on surface of fibers.

  4. Rayleigh scattering in the atmospheres of hot stars

    CERN Document Server

    Fišák, Jakub; Munzar, Dominik; Kubát, Jiří

    2016-01-01

    Rayleigh scattering is a result of an interaction of photons with bound electrons. Rayleigh scattering is mostly neglected in calculations of hot star model atmospheres because most of the hydrogen atoms are ionized and the heavier elements have a lower abundance than hydrogen. In atmospheres of some chemically peculiar stars, helium overabundant regions containing singly ionized helium are present and Rayleigh scattering can be a significant opacity source. We evaluate the contribution of Rayleigh scattering by neutral hydrogen and singly ionized helium in the atmospheres of hot stars with solar composition and in the atmospheres of helium overabundant stars. We computed several series of model atmospheres using the TLUSTY code and emergent fluxes using the SYNSPEC code. These models describe atmospheres of main sequence B-type stars with different helium abundance. We used an existing grid of models for atmospheres with solar chemical composition and we calculated an additional grid for helium-rich stars wi...

  5. Designing Dynamic Atmospheres

    DEFF Research Database (Denmark)

    Højlund, Marie; Kinch, Sofie

    2012-01-01

    This paper addresses the notion of atmospheres from a designerly perspective, and discusses temporal challenges facing interaction designers when acknowledging the dynamic character of it. As atmospheres are created in the relation between body, space, and time, a pragmatic approach seems useful...

  6. Proterozoic atmospheric oxygen

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene

    2014-01-01

    This article is concerned with the evolution of atmospheric oxygen concentrations through the Proterozoic Eon. In particular, this article will seek to place the history of atmospheric oxygenation through the Proterozoic Eon in the context of the evolving physical environment including the histor...

  7. Clouds in Planetary Atmospheres

    Science.gov (United States)

    West, R.; Murdin, P.

    2000-11-01

    What are clouds? The answer to that question is both obvious and subtle. In the terrestrial atmosphere clouds are familiar as vast collections of small water drops or ice crystals suspended in the air. In the atmospheres of Venus, Mars, Jupiter, Saturn, Saturn's moon Titan, Uranus, Neptune, and possibly Pluto, they are composed of several other substances including sulfuric acid, ammonia, hydroge...

  8. Optical Intensity Interferometry through Atmospheric Turbulence

    CERN Document Server

    Tan, Peng Kian; Kurtsiefer, Christian

    2015-01-01

    Conventional ground-based astronomical observations suffer from image distortion due to atmospheric turbulence. This can be minimized by choosing suitable geographic locations or adaptive optical techniques, and avoided altogether by using orbital platforms outside the atmosphere. One of the promises of optical intensity interferometry is its independence from atmospherically induced phase fluctuations. By performing narrowband spectral filtering on sunlight and conducting temporal intensity interferometry using actively quenched avalanche photon detectors (APDs), the Solar $g^{(2)}(\\tau)$ signature was directly measured. We observe an averaged photon bunching signal of $g^{(2)}(\\tau) = 1.693 \\pm 0.003$ from the Sun, consistently throughout the day despite fluctuating weather conditions, cloud cover and elevation angle. This demonstrates the robustness of the intensity interferometry technique against atmospheric turbulence and opto-mechanical instabilities, and the feasibility to implement measurement scheme...

  9. Optical intensity interferometry through atmospheric turbulence

    Science.gov (United States)

    Tan, P. K.; Chan, A. H.; Kurtsiefer, C.

    2016-04-01

    Conventional ground-based astronomical observations suffer from image distortion due to atmospheric turbulence. This can be minimized by choosing suitable geographic locations or adaptive optical techniques, and avoided altogether by using orbital platforms outside the atmosphere. One of the promises of optical intensity interferometry is its independence from atmospherically induced phase fluctuations. By performing narrow-band spectral filtering on sunlight and conducting temporal intensity interferometry using actively quenched avalanche photodiodes, the Solar g(2)(τ) signature was directly measured. We observe an averaged photon bunching signal of g(2)(τ) = 1.693 ± 0.003 from the Sun, consistently throughout the day despite fluctuating weather conditions, cloud cover and elevation angle. This demonstrates the robustness of the intensity interferometry technique against atmospheric turbulence and opto-mechanical instabilities, and the feasibility to implement measurement schemes with both large baselines and long integration times.

  10. The Nature of the Radiative Hydrodynamic Instabilities in Radiatively Supported Thomson Atmospheres

    CERN Document Server

    Shaviv, N J

    2001-01-01

    Atmospheres having a significant radiative support are shown to be intrinsically unstable at luminosities above a critical fraction Gamma_crit ~ 0.5-0.85 of the Eddington limit, with the exact value depending on the boundary conditions. Two different types of absolute radiation-hydrodynamic instabilities of acoustic waves are found to take place even in the electron scattering dominated limit. Both instabilities grow over dynamical time scales and both operate on non radial modes. One is stationary and arises only after the effects of the boundary conditions are taken into account, while the second is a propagating wave and is insensitive to the boundary conditions. Although a significant wind can be generated by these instabilities even below the classical Eddington luminosity limit, quasi-stable configurations can exist beyond the Eddington limit due to the generally reduced effective opacity. The study is done using a rigorous numerical linear analysis of a gray plane parallel atmosphere under the Eddingto...

  11. Ambient Electronics

    Science.gov (United States)

    Sekitani, Tsuyoshi; Someya, Takao

    2012-10-01

    We report the recent research progress and future prospects of flexible and printed electronics, focusing on molecular electronic material-based thin-film transistors, which are expected to usher in a new era of electronics.

  12. Reconciling dark matter, solar and atmospheric neutrinos

    CERN Document Server

    Peltoniemi, J T

    1993-01-01

    We present models that can reconcile the solar and atmospheric neutrino data with the existence of a hot dark matter component in the universe. This dark matter is a quasi-Dirac neutrino whose mass $m_{DM}$ arises at the one-loop level. The solar neutrino deficit is explained via nonadiabatic conversions of electron neutrino to a sterile neutrino and the atmospheric neutrino data via maximal muon neutrino to tau neutrino oscillations generated by higher order loop diagrams. For $m_{DM} \\sim 30$ eV the radiative neutrino decay can lead to photons that can ionize interstellar hydrogen. In one of the models one can have observable $\

  13. Atmospheric composition change: Ecosystems–Atmosphere interactions

    DEFF Research Database (Denmark)

    Fowler, D.; Pilegaard, Kim; Sutton, M.A.

    2009-01-01

    and techniques in micrometeorology. For some of the compounds there have been paradigm shifts in approach and application of both techniques and assessment. These include flux measurements over marine surfaces and urban areas using micrometeorological methods and the up-scaling of flux measurements using...... in the size range 1 nm–10 μm including organic and inorganic chemical species. The main focus of the review is on the exchange between terrestrial ecosystems, both managed and natural and the atmosphere, although some new developments in ocean–atmosphere exchange are included. The material presented is biased...... towards the last decade, but includes earlier work, where more recent developments are limited or absent. New methodologies and instrumentation have enabled, if not driven technical advances in measurement. These developments have advanced the process understanding and upscaling of fluxes, especially...

  14. Atmospheric radiation flight dose rates

    Science.gov (United States)

    Tobiska, W. K.

    2015-12-01

    Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. Of the domains that are affected by space weather, the coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Space Environment Technologies (SET) has been conducting space weather observations of the atmospheric radiation environment at aviation altitudes that will eventually be transitioned into air traffic management operations. The Automated Radiation Measurements for Aerospace Safety (ARMAS) system and Upper-atmospheric Space and Earth Weather eXperiment (USEWX) both are providing dose rate measurements. Both activities are under the ARMAS goal of providing the "weather" of the radiation environment to improve aircraft crew and passenger safety. Over 5-dozen ARMAS and USEWX flights have successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the real-time radiation environment resulting from Galactic Cosmic Rays and Solar Energetic Particles. The real-time radiation exposure is computed as an effective dose rate (body-averaged over the radiative-sensitive organs and tissues in units of microsieverts per hour); total ionizing dose is captured on the aircraft, downlinked in real-time, processed on the ground into effective dose rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users via the web and smart phone apps. Flight altitudes now exceed 60,000 ft. and extend above commercial aviation altitudes into the stratosphere. In this presentation we describe recent ARMAS and USEWX results.

  15. Electron cooling

    Science.gov (United States)

    Meshkov, I.; Sidorin, A.

    2004-10-01

    The brief review of the most significant and interesting achievements in electron cooling method, which took place during last two years, is presented. The description of the electron cooling facilities-storage rings and traps being in operation or under development-is given. The applications of the electron cooling method are considered. The following modern fields of the method development are discussed: crystalline beam formation, expansion into middle and high energy electron cooling (the Fermilab Recycler Electron Cooler, the BNL cooler-recuperator, cooling with circulating electron beam, the GSI project), electron cooling in traps, antihydrogen generation, electron cooling of positrons (the LEPTA project).

  16. Glacial atmospheric phosphorus deposition

    Science.gov (United States)

    Kjær, Helle Astrid; Dallmayr, Remi; Gabrieli, Jacopo; Goto-Azuma, Kumiko; Hirabayashi, Motohiro; Svensson, Anders; Vallelonga, Paul

    2016-04-01

    Phosphorus in the atmosphere is poorly studied and thus not much is known about atmospheric phosphorus and phosphate transport and deposition changes over time, though it is well known that phosphorus can be a source of long-range nutrient transport, e.g. Saharan dust transported to the tropical forests of Brazil. In glacial times it has been speculated that transport of phosphorus from exposed shelves would increase the ocean productivity by wash out. However whether the exposed shelf would also increase the atmospheric load to more remote places has not been investigated. Polar ice cores offer a unique opportunity to study the atmospheric transport of aerosols on various timescales, from glacial-interglacial periods to recent anthropogenic influences. We have for the first time determined the atmospheric transport of phosphorus to the Arctic by means of ice core analysis. Both total and dissolved reactive phosphorus were measured to investigate current and past atmospheric transport of phosphorus to the Arctic. Results show that glacial cold stadials had increased atmospheric total phosphorus mass loads of 70 times higher than in the past century, while DRP was only increased by a factor of 14. In the recent period we find evidence of a phosphorus increase over the past 50 yrs in ice cores close to human occupation likely correlated to forest fires. References: Kjær, Helle Astrid, et al. "Continuous flow analysis method for determination of dissolved reactive phosphorus in ice cores." Environmental science & technology 47.21 (2013): 12325-12332. Kjær, Helle Astrid, et al. "Greenland ice cores constrain glacial atmospheric fluxes of phosphorus." Journal of Geophysical Research: Atmospheres120.20 (2015).

  17. Marine atmospheric corrosion of carbon steels

    Energy Technology Data Exchange (ETDEWEB)

    Morcillo, M.; Alcantara, J.; Diaz, I.; Chico, B.; Simancas, J.; Fuente, D. de la

    2015-07-01

    Basic research on marine atmospheric corrosion of carbon steels is a relatively young scientific field and there continue to be great gaps in this area of knowledge. The presence of akaganeite in the corrosion products that form on steel when it is exposed to marine atmospheres leads to a notable increase in the corrosion rate. This work addresses the following issues: (a) environmental conditions necessary for akaganeite formation; (b) characterisation of akaganeite in the corrosion products formed; (c) corrosion mechanisms of carbon steel in marine atmospheres; (d) exfoliation of rust layers formed in highly aggressive marine atmospheres; (e) long-term corrosion rate prediction; and (f) behaviour of weathering steels. Field research has been carried out at Cabo Vilano wind farm (Camarinas, Galicia) in a wide range of atmospheric salinities and laboratory work involving the use of conventional atmospheric corrosion techniques and near-surface and bulk sensitive analytical techniques: scanning electron microscopy (SEM)/energy dispersive spectrometry (EDS), X-ray diffraction (XRD), Mossbauer spectroscopy and SEM/μRaman spectroscopy. (Author)

  18. Atmosphere beyond Poetics

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2014-01-01

    . In doing so, analysing the Crystal Palace – recognised as the epitome of controlled immersive experience as well as of atmospheric engineering (Sloterdijk 2008 (2005) – in parallel with other examples and theoretical explorations, will provide a canvas for discerning the means of creation of atmosphere...... Physical Presence in Space.” Oase #91, Building Atmosphere, 21-33 Sloterdijk, Peter. (2005) 2008. “The Crystal Palace.” Translated by Michael Darroch. Public 37: Public?, 12-15. Originally published in Peter Sloterdijk. Im Weltinnenraum des Kapitals: Für eine philoso-phische Theorie der Globalisierung, 265...

  19. Dust ablation in Pluto's atmosphere

    Science.gov (United States)

    Horanyi, Mihaly; Poppe, Andrew; Sternovsky, Zoltan

    2016-04-01

    Based on measurements by dust detectors onboard the Pioneer 10/11 and New Horizons spacecraft the total production rate of dust particles born in the Edgeworth Kuiper Belt (EKB) has been be estimated to be on the order of 5 ṡ 103 kg/s in the approximate size range of 1 - 10 μm. Dust particles are produced by collisions between EKB objects and their bombardment by both interplanetary and interstellar dust particles. Dust particles of EKB origin, in general, migrate towards the Sun due to Poynting-Robertson drag but their distributions are further sculpted by mean-motion resonances as they first approach the orbit of Neptune and later the other planets, as well as mutual collisions. Subsequently, Jupiter will eject the vast majority of them before they reach the inner solar system. The expected mass influx into Pluto atmosphere is on the order of 200 kg/day, and the arrival speed of the incoming particles is on the order of 3 - 4 km/s. We have followed the ablation history as function of speed and size of dust particles in Pluto's atmosphere, and found that volatile rich particles can fully sublimate due to drag heating and deposit their mass in narrow layers. This deposition might promote the formation of the haze layers observed by the New Horizons spacecraft. This talk will explore the constraints on the composition of the dust particles by comparing the altitude of the deposition layers to the observed haze layers.

  20. Descargas atmosféricas e interrupções de energia elétrica na área da CHESF: relação com variáveis atmosféricas em anos de El Niño e La Niña Breaks in electric power supply due to atmospheric discharges in CHESF management area

    Directory of Open Access Journals (Sweden)

    Wendell Rondinelli Gomes Farias

    2008-09-01

    Full Text Available Condições climáticas e ambientais influenciam diretamente no desenvolvimento e intensificação de tempestades seguidas de descargas atmosféricas, e são responsáveis por interrupções no fornecimento de energia elétrica no Nordeste do Brasil. Este estudo tem como objetivo estabelecer relações entre variáveis meteorológicas, que permitam equacionar a influência de condições ambientais na intensificação de atividade convectiva responsável por interrupções no fornecimento de energia elétrica por descargas atmosféricas em anos de El Niño e La Nina. As análises são restritas à área de atuação da CHESF (Companhia Hidro Elétrica do São Francisco, a qual tem grande parte das Linhas de Transmissão de energia instaladas no semi-árido do Nordeste do Brasil. O método de componentes principais escolhido como principal ferramenta de análise permitiu isolar padrões significativos de umidade, vento e temperatura no domínio analisado. Vórtices ciclônicos em altos níveis (VCAN, foram os principais responsáveis pelo desenvolvimento de sistemas precipitantes intensos e ocorrências de falhas transitórias no sistema de transmissão da CHESF.Climatic and environmental conditions directly influence the development and the intensification of storms followed by atmospheric discharges and they are responsible for interruptions in the electric energy supply in the Northeast of Brazil. This study has as objective to establish relations between meteorological variables that allow formulating the influence of environmental conditions to the intensification of convective activity responsible for interruptions of the electric energy supply during years of El Niño and La Nina. The analyses are restricted to the CHESF (Companhia Hidro Elétrica do São Francisco activity areas having most of its energy Transmission Lines installed in the semi-arid of Northeastern Brazil. The method of principal component analysis chosen as main analysis

  1. The H.E.S.S. measurement of the cosmic-ray electron spectrum

    Science.gov (United States)

    Egberts, Kathrin; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A. R.; Becherini, Y.; Behera, B.; Bernlühr, K.; Bochow, A.; Boisson, C.; Bolmont, J.; Borrel, V.; Brucker, J.; Brun, F.; Brun, P.; Bühler, R.; Bulik, T.; Büsching, I.; Boutelier, T.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Conrad, J.; Chounet, L.-M.; Clapson, A. C.; Coignet, G.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; Dickinson, H. J.; Domainko, A. Djannati-Ataü W.; Drury, L. O'c.; Dubois, F.; Dubus, G.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fiasson, A.; Fürster, A.; Fontaine, G.; Füssling, M.; Gabici, S.; Gallant, Y. A.; Gérard, L.; Gerbig, D.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Goret, P.; Güring, D.; Hampf, D.; Hauser, M.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hinton, J. A.; Hoffmann, A.; Hofmann, W.; Hofverberg, P.; Holleran, M.; Hoppe, S.; Horns, D.; Jacholkowska, A.; de Jager, O. C.; Jahn, C.; Jung, I.; Katarzynski, K.; Katz, U.; Kaufmann, S.; Kerschhaggl, M.; Khangulyan, D.; Khálifi, B.; Keogh, D.; Klochkov, D.; Kluzniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Lamanna, G.; Lenain, J.-P.; Lohse, T.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maurin, D.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Moderski, R.; Moulin, E.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nekrassov, D.; Nguyen, N.; Nicholas, B.; Niemiec, J.; Nolan, S. J.; Ohm, S.; Olive, J.-F.; de Ona Wilhelmi, E.; Opitz, B.; Orford, K. J.; Ostrowski, M.; Panter, M.; Paz Arribas, M.; Pedaletti, G.; Pelletier, G.; Petrucci, P.-O.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raubenheimer, B. C.; Raue, M.; Rayner, S. M.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Ruppel, J.; Ryde, F.; Sahakian, V.; Santangelo, A.; Schlickeiser, R.; Schück, F. M.; Schünwald, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Shalchi, A.; Sushch, I.; Sikora, M.; Skilton, J. L.; Sol, H.; Stawarz, L.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Szostek, A.; Tam, P. H.; Tavernet, J.-P.; Terrier, R.; Tibolla, O.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Venter, L.; Vialle, J. P.; Viana, A.; Vincent, P.; Vivier, M.; Vülk, H. J.; Volpe, F.; Vorobiov, S.; Wagner, S. J.; Ward, M.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.

    The measurement of very-high-energy cosmic-ray electrons is intrinsically difficult due to their very steep spectrum with low fluxes and an enormous background of hadronic cosmic rays. The large collection areas needed for such a measurement can be provided by ground-based imaging atmospheric Cherenkov telescopes. The High Energy Stereoscopic System (H.E.S.S.) has performed the first ground-based cosmic-ray electron measurement and thereby extended the measured range of the spectrum to several TeV.

  2. Physics of Atmospheric Electric Discharges in Gases: An Informal Introduction

    CERN Document Server

    Treumann, R A; Parrot, M

    2007-01-01

    A short account of the physics of electrical discharges in gases is given in view of its historical evolution and application to planetary atmospheres. As such it serves as an introduction to the articles on particular aspects of electric discharges contained in this book, in particular in the chapters on lightning and the violent discharges which in the recent two decades have been observed to take place in Earth's upper atmosphere. In addition of briefly reviewing the early history of gas discharge physics we discuss the main parameters affecting violent atmospheric discharges like collision frequency, mean free path and critical electric field strength. Any discharge current in the atmosphere is clearly carried only by electrons. Above the lower bound of the mesosphere the electrons must be considered magnetized with the conductivity becoming a tensor. Moreover, the collisional mean free path in the upper atmosphere becomes relatively large which lowers the critical electric field there and more easily ena...

  3. Magnetized neutron star atmospheres: beyond cool plasma approximation

    CERN Document Server

    Suleimanov, V F; Werner, K

    2012-01-01

    All the neutron star (NS) atmosphere models published so far have been calculated in the "cold plasma approximation", which neglects the relativistic effects in the radiative processes, such as cyclotron emission/absorption at harmonics of cyclotron frequency. Here we present new NS atmosphere models which include such effects. We calculate a set of models for effective temperatures T_eff =1-3 MK and magnetic fields B \\sim 10^{10}-10^{11} G, typical for the so-called central compact objects (CCOs) in supernova remnants, for which the electron cyclotron energy E_{c,e} and its first harmonics are in the observable soft X-ray range. Although the relativistic parameters, such as kT_eff /(m_e c^2) and E_{c,e} /(m_e c^2), are very small for CCOs, the relativistic effects substantially change the emergent spectra at the cyclotron resonances, E \\approx sE_{c,e} (s=1, 2,...). Although the cyclotron absorption features can form in a cold plasma due to the quantum oscillations of the free-free opacity, the shape and dep...

  4. Atmospheric Variations as observed by IceCube

    CERN Document Server

    Tilav, Serap; Kuwabara, Takao; Rocco, Dominick; Rothmaier, Florian; Simmons, Matt; Wissing, Henrike

    2010-01-01

    We have measured the correlation of rates in IceCube with long and short term variations in the South Pole atmosphere. The yearly temperature variation in the middle stratosphere (30-60 hPa) is highly correlated with the high energy muon rate observed deep in the ice, and causes a +/-10% seasonal modulation in the event rate. The counting rates of the surface detectors, which are due to secondary particles of relatively low energy (muons, electrons and photons), have a negative correlation with temperatures in the lower layers of the stratosphere (40-80 hPa), and are modulated at a level of +/-5%. The region of the atmosphere between pressure levels 20-120 hPa, where the first cosmic ray interactions occur and the produced pions/kaons interact or decay to muons, is the Antarctic ozone layer. The anticorrelation between surface and deep ice trigger rates reflects the properties of pion/kaon decay and interaction as the density of the stratospheric ozone layer changes. Therefore, IceCube closely probes the ozon...

  5. Carbon neutron star atmospheres

    CERN Document Server

    Suleimanov, V F; Pavlov, G G; Werner, K

    2013-01-01

    The accuracy of measuring the basic parameters of neutron stars is limited in particular by uncertainties in chemical composition of their atmospheres. For example, atmospheres of thermally - emitting neutron stars in supernova remnants might have exotic chemical compositions, and for one of them, the neutron star in CasA, a pure carbon atmosphere has recently been suggested by Ho & Heinke (2009). To test such a composition for other similar sources, a publicly available detailed grid of carbon model atmosphere spectra is needed. We have computed such a grid using the standard LTE approximation and assuming that the magnetic field does not exceed 10^8 G. The opacities and pressure ionization effects are calculated using the Opacity Project approach. We describe the properties of our models and investigate the impact of the adopted assumptions and approximations on the emergent spectra.

  6. The invention of atmosphere.

    Science.gov (United States)

    Martin, Craig

    2015-08-01

    The word "atmosphere" was a neologism Willebrord Snellius created for his Latin translation of Simon Stevin's cosmographical writings. Astronomers and mathematical practitioners, such as Snellius and Christoph Scheiner, applying the techniques of Ibn Mu'ādh and Witelo, were the first to use the term in their calculations of the height of vapors that cause twilight. Their understandings of the atmosphere diverged from Aristotelian divisions of the aerial region. From the early years of the seventeenth century, the term was often associated with atomism or corpuscular matter theory. The concept of the atmosphere changed dramatically with the advent of pneumatic experiments in the middle of the seventeenth century. Pierre Gassendi, Walter Charleton, and Robert Boyle transformed the atmosphere of the mathematicians giving it the characteristics of weight, specific gravity, and fluidity, while disputes about its extent and border remained unresolved.

  7. Relativistic electron beams above thunderclouds

    Directory of Open Access Journals (Sweden)

    M. Füllekrug

    2011-05-01

    Full Text Available Non-luminous relativistic electron beams above thunderclouds are detected by radio remote sensing with low frequency radio signals from 40–400 kHz. The electron beams occur 2–9 ms after positive cloud-to-ground lightning discharges at heights between 22–72 km above thunderclouds. The positive lightning discharges also cause sprites which occur either above or before the electron beam. One electron beam was detected without any luminous sprite occurrence which suggests that electron beams may also occur independently. Numerical simulations show that the beamed electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of 7 MeV to transport a total charge of 10 mC upwards. The impulsive current associated with relativistic electron beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit.

  8. Atmospheric muons: experimental aspects

    OpenAIRE

    Cecchini, S.; Spurio, M.

    2012-01-01

    We present a review of atmospheric muon flux and energy spectrum measurements over almost six decades of muon momentum. Sea-level and underground/water/ice experiments are considered. Possible sources of systematic errors in the measurements are examinated. The characteristics of underground/water muons (muons in bundle, lateral distribution, energy spectrum) are discussed. The connection between the atmospheric muon and neutrino measurements are also reported.

  9. Atmospheric muons: experimental aspects

    Directory of Open Access Journals (Sweden)

    S. Cecchini

    2012-11-01

    Full Text Available We present a review of atmospheric muon flux and energy spectrum measurements over almost six decades of muon momentum. Sea level and underground/water/ice experiments are considered. Possible sources of systematic errors in the measurements are examined. The characteristics of underground/water muons (muons in bundle, lateral distribution, energy spectrum are discussed. The connection between the atmospheric muon and neutrino measurements are also reported.

  10. Global atmospheric changes.

    OpenAIRE

    Piver, W T

    1991-01-01

    Increasing concentrations of CO2 and other greenhouse gases in the atmosphere can be directly related to global warming. In terms of human health, because a major cause of increasing atmospheric concentrations of CO2 is the increased combustion of fossil fuels, global warming also may result in increases in air pollutants, acid deposition, and exposure to ultraviolet (UV) radiation. To understand better the impacts of global warming phenomena on human health, this review emphasizes the proces...

  11. XUV complex refractive indices of aerosols in the atmospheres of Titan and the primitive Earth

    Science.gov (United States)

    Gavilan, Lisseth; Neumann, Maciej; Bulkin, Pavel; Popescu, Horia; Steffan, Martin; Esser, Norbert; Carrasco, Nathalie

    2016-10-01

    The complex refractive indices of tholins, simulating aerosols in the atmosphere of Titan and the primitive earth, have been measured over a wide spectral range, including the soft X-ray, vacuum-ultraviolet (VUV), and UV-Visible. The soft X-ray and VUV spectral ranges are in particular relevant to radiative transfer models of solar irradiation of primitive atmospheres (Lammer et al. 2008) and may elucidate the (anti-)greenhouse potential of photochemical aerosols.Thin films were grown using the PAMPRE capacitively coupled plasma setup (Szopa et al. 2006; Carrasco et al. 2009). Gas mixtures consisting of CH4/N2 with 5:95 ratios were used to simulate Titan's atmospheric composition. For the primitive Earth, gas mixtures of N2/CO2/H2 and N2/CO2/CH4 were used as described in Fleury et al. (2014).State-of-the-art laboratory techniques were used to determine the refractive indices of such tholin films. These include VUV ellipsometry (performed in collaboration with the Metrology Light Source in Berlin) and synchrotron X-ray spectroscopy (performed at the SEXTANTS beamline of the SOLEIL synchrotron). While VUV spectroscopy reveals new electronic transitions due to plasmon resonances in tholins, X-ray spectra reveal the C and O absorption edges of these solids. The refractive indices are compared to results from Khare et al. (1984). Implications on the optical properties of these aerosol analogs on the radiative modeling of primitive atmospheres will be discussed.

  12. Inhomogeneous cloud coverage through the Coulomb explosion of dust in substellar atmospheres

    CERN Document Server

    Stark, Craig R; Diver, Declan A

    2015-01-01

    Recent observations of brown dwarf spectroscopic variability in the infrared infer the presence of patchy cloud cover. This paper proposes a mechanism for producing inhomogeneous cloud coverage due to the depletion of cloud particles through the Coulomb explosion of dust in atmospheric plasma regions. Charged dust grains Coulomb-explode when the electrostatic stress of the grain exceeds its mechanical tensile stress, which results in grains below a critical radius $aatmospheres, the effect on the dust particle size distribution function, and the resulting radiative properties of the atmospheric regions. Our results show that for an atmospheric plasma region with an electron temperature of $T_{e}=10$~eV ($\\approx10^{5}$~K), the critical grain radius varies from $10^{-7}$ to $10^{-4}$~cm, depending on the grains' tensile strength. Higher critical radii up to $10^{-3}$~cm ...

  13. Brown Dwarf Model Atmospheres Based on Multi-Dimensional Radiation Hydrodynamics

    Science.gov (United States)

    Allard, France; Freytag, Bernd

    2010-11-01

    The atmospheres of Brown Dwarfs (BDs) are the site of molecular opacities and cloud formation, and control their cooling rate, radius and brightness evolution. Brown dwarfs evolve from stellar-like properties (magnetic activity, spots, flares, mass loss) to planet-like properties (electron degeneracy of the interior, cloud formation, dynamical molecular transport) while retaining, due to their fully convective interior, larger rotational velocities (≤ 30 km/s i.e. P objects. While the pure gas-phase based NextGen model atmospheres (Allard et al. 1997, Hauschildt et al. 1999) have allowed the understanding of the several populations of Very Low Mass Stars (VLMs), the AMES-Dusty models (Allard et al. 2001) based on equilibrium chemistry have reproduced some near-IR photometric properties of M and L-type brown dwarfs, and played a key role in the determination of the mass of brown dwarfs and Planetary Mass Objects (PMOs) in the eld and in young stellar clusters. In this paper, we present a new model atmosphere grid for VLMs, BDs, PMOs named BT-Settl, which includes a cloud model and dynamical molecular transport based on mixing information from 2D Radiation Hydrodynamic (RHD) simulations (Freytag et al. 2009). We also present the status of our 3D RHD simulations including rotation (Coriolis forces) of a cube on the surface of a brown dwarf. The BT-Settl model atmosphere grid will be available shortly via the Phoenix web simulator (http://phoenix.ens-lyon.fr/simulator/).

  14. Investigation of sounding rocket observations of field-aligned currents and electron temperature

    Science.gov (United States)

    Cohen, I. J.; Lessard, M.; Zettergren, M. D.; Moen, J.; Lynch, K. A.; Heavisides, J. M.

    2014-12-01

    Strangeway et al. [2005] and other authors have concluded that the establishment of the ambipolar field by the deposition of energy from soft electron precipitation is a significant driver of type-2 ion upflows. Likewise, Clemmons et al. [2008] and Zhang et al. [2012] proposed processes by which soft electron precipitation may play a role in heating neutrals and contribute to neutral upwelling. In both situations the thermal ionospheric electron population plays a crucial role in both generation of the ambipolar field and in collisional energy exchange with the atmosphere through a variety of processes. In this study we examine the dynamics of the electron population, specifically the temperature, in a slightly different context - focusing on the auroral downward current region (DCR). In many cases auroral DCRs may be depleted of plasma, which sets up interesting conditions involving thermoelectric heat fluxes (which flow upward - in the opposite direction from the current), adiabatic expansion due to the high (upward) speed of the electrons carrying the downward current, heat exchange from ions which have elevated temperatures due to frictional heating, and direct frictional heating of the electrons. A detailed understanding of the electron temperature in auroral DCRs is necessary to make quantitative statements about recombination, upflow, cavitation and a host of other processes relevant to ion outflow. In this study, we compare in situ rocket observations of electron temperature, density, and current densities with predictions from the Zettergren and Semeter [2012] model in an attempt to better understand the dynamics and relationships between these parameters in DCRs.

  15. Occultations for probing atmosphere and climate

    CERN Document Server

    Foelsche, Ulrich; Steiner, Andrea

    2004-01-01

    Use of occultation methodology for observing the Earth's atmosphere and climate has become so broad as to comprise solar, lunar, stellar, navigation and satellite­ crosslink occultation methods. The atmospheric parameters obtained extend from the fundamental variables temperature, density, pressure, water vapor, and ozone via a multitude of trace gas species to particulate species such as aerosols and cloud liquid water. Ionospheric electron density is sensed as well. The methods all share the key properties of self-calibration, high accuracy and vertical resolution, global coverage, and (if using radio signals) all-weather capability. Occultation data are thus of high value in a wide range of fields including climate monitoring and research, atmospheric physics and chemistry, operational meteorology, and other fields such as space weather and planetary science. This wide area of variants and uses of the occultation method has led to a diversi­ fication of the occultation-related scientific community into a...

  16. US-Total Electron Content Product (USTEC)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The US Total Electron Content (US-TEC) product is designed to specify TEC over the Continental US (CONUS) in near real-time. The product uses a Kalman Filter data...

  17. Loss rates of Europa's tenuous atmosphere

    Science.gov (United States)

    Lucchetti, Alice; Plainaki, Christina; Cremonese, Gabriele; Milillo, Anna; Cassidy, Timothy; Jia, Xianzhe; Shematovich, Valery

    2016-10-01

    Loss processes in Europa's tenuous atmosphere are dominated by plasma-neutral interactions. Based on the updated data of the plasma conditions in the vicinity of Europa (Bagenal et al. 2015), we provide estimations of the atmosphere loss rates for the H2O, O2 and H2 populations. Due to the high variability of the plasma proprieties, we perform our investigation for three sample plasma environment cases identified by Bagenal et al. as hot/low density, cold/high density, and an intermediate case. The role of charge-exchange interactions between atmospheric neutrals and three different plasma populations, i.e. magnetospheric, pickup, and ionospheric ions, is examined in detail. Our assumptions related to the pickup and to the ionospheric populations are based on the model by Sittler et al. (2013). We find that O2-O2+ charge-exchange is the fastest loss process for the most abundant atmospheric species O2, though this loss process has been neglected in previous atmospheric models. Using both the revised O2 column density obtained from the EGEON model (Plainaki et al., 2013) and the current loss rate estimates, we find that the upper limit for the volume integrated loss rate due to O2-O2+ charge exchange is in the range (13-51)×1026 s-1, depending on the moon's orbital phase and illumination conditions. The results of the current study are relevant to the investigation of Europa's interaction with Jupiter's magnetospheric plasma.

  18. The collapse of Io's primary atmosphere in Jupiter eclipse

    Science.gov (United States)

    Tsang, Constantine C. C.; Spencer, John R.; Lellouch, Emmanuel; Lopez-Valverde, Miguel A.; Richter, Matthew J.

    2016-08-01

    Volcanic outgassing due to tidal heating is the ultimate source of a tenuous SO2 atmosphere around Jupiter's moon Io. The question of whether SO2 frost on the surface plays a part, and to what degree, in maintaining Io's atmosphere with the constant volcanic outgassing is still debated. It is believed that for a sublimation-supported atmosphere, the primary atmosphere should collapse during eclipses by Jupiter, as the SO2 vapor pressure is strongly coupled to the temperature of the ice on the surface. No direct observations of Io's atmosphere in eclipse have previously been possible, due to the simultaneous need for high spectral and time sensitivity, as well as a high signal-to-noise ratio. Here we present the first ever high-resolution spectra at 19 µm of Io's SO2 atmosphere in Jupiter eclipse from the Gemini telescope. The strongest atmospheric band depth is seen to dramatically decay from 2.5 ± (0.08)% before the eclipse to 0.18 ± (0.16)% after 40 min in eclipse. Further modeling indicates that the atmosphere has collapsed shortly after eclipse ingress, implying that the atmosphere of Io has a strong sublimation-controlled component. The atmospheric column density—from pre-eclipse to in-eclipse—drops by a factor of 5 ± 2.

  19. Engineered phages for electronics.

    Science.gov (United States)

    Cui, Yue

    2016-11-15

    Phages are traditionally widely studied in biology and chemistry. In recent years, engineered phages have attracted significant attentions for functionalization or construction of electronic devices, due to their specific binding, catalytic, nucleating or electronic properties. To apply the engineered phages in electronics, these are a number of interesting questions: how to engineer phages for electronics? How are the engineered phages characterized? How to assemble materials with engineered phages? How are the engineered phages micro or nanopatterned? What are the strategies to construct electronics devices with engineered phages? This review will highlight the early attempts to address these questions and explore the fundamental and practical aspects of engineered phages in electronics, including the approaches for selection or expression of specific peptides on phage coat proteins, characterization of engineered phages in electronics, assembly of electronic materials, patterning of engineered phages, and construction of electronic devices. It provides the methodologies and opens up ex-cit-ing op-por-tu-ni-ties for the development of a variety of new electronic materials and devices based on engineered phages for future applications.

  20. Atomic and electronic structure of exfoliated black phosphorus

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ryan J.; Topsakal, Mehmet; Jeong, Jong Seok; Wentzcovitch, Renata M.; Mkhoyan, K. Andre, E-mail: mkhoyan@umn.edu [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Low, Tony; Robbins, Matthew C.; Haratipour, Nazila; Koester, Steven J. [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2015-11-15

    Black phosphorus, a layered two-dimensional crystal with tunable electronic properties and high hole mobility, is quickly emerging as a promising candidate for future electronic and photonic devices. Although theoretical studies using ab initio calculations have tried to predict its atomic and electronic structure, uncertainty in its fundamental properties due to a lack of clear experimental evidence continues to stymie our full understanding and application of this novel material. In this work, aberration-corrected scanning transmission electron microscopy and ab initio calculations are used to study the crystal structure of few-layer black phosphorus. Directly interpretable annular dark-field images provide a three-dimensional atomic-resolution view of this layered material in which its stacking order and all three lattice parameters can be unambiguously identified. In addition, electron energy-loss spectroscopy (EELS) is used to measure the conduction band density of states of black phosphorus, which agrees well with the results of density functional theory calculations performed for the experimentally determined crystal. Furthermore, experimental EELS measurements of interband transitions and surface plasmon excitations are also consistent with simulated results. Finally, the effects of oxidation on both the atomic and electronic structure of black phosphorus are analyzed to explain observed device degradation. The transformation of black phosphorus into amorphous PO{sub 3} or H{sub 3}PO{sub 3} during oxidation may ultimately be responsible for the degradation of devices exposed to atmosphere over time.

  1. Atmospheric Neutrinos in the MINOS Far Detector

    Energy Technology Data Exchange (ETDEWEB)

    Howcroft, Caius L.F.

    2004-12-01

    The phenomenon of flavour oscillations of neutrinos created in the atmosphere was first reported by the Super-Kamiokande collaboration in 1998 and since then has been confirmed by Soudan 2 and MACRO. The MINOS Far Detector is the first magnetized neutrino detector able to study atmospheric neutrino oscillations. Although it was designed to detect neutrinos from the NuMI beam, it provides a unique opportunity to measure the oscillation parameters for neutrinos and anti-neutrinos independently. The MINOS Far Detector was completed in August 2003 and since then has collected 2.52 kton-years of atmospheric data. Atmospheric neutrino interactions contained within the volume of the detector are separated from the dominant background from cosmic ray muons. Thirty seven events are selected with an estimated background contamination of less than 10%. Using the detector's magnetic field, 17 neutrino events and 6 anti-neutrino events are identified, 14 events have ambiguous charge. The neutrino oscillation parameters for {nu}{sub {mu}} and {bar {nu}}{sub {mu}} are studied using a maximum likelihood analysis. The measurement does not place constraining limits on the neutrino oscillation parameters due to the limited statistics of the data set analysed. However, this thesis represents the first observation of charge separated atmospheric neutrino interactions. It also details the techniques developed to perform atmospheric neutrino analyses in the MINOS Far Detector.

  2. Atmospheric Neutrinos in the MINOS Far Detector

    Energy Technology Data Exchange (ETDEWEB)

    Howcroft, Caius Leo Frederick [Univ. of Cambridge (United Kingdom)

    2004-12-01

    The phenomenon of flavour oscillations of neutrinos created in the atmosphere was first reported by the Super-Kamiokande collaboration in 1998 and since then has been confirmed by Soudan 2 and MACRO. The MINOS Far Detector is the first magnetized neutrino detector able to study atmospheric neutrino oscillations. Although it was designed to detect neutrinos from the NuMI beam, it provides a unique opportunity to measure the oscillation parameters for neutrinos and anti-neutrinos independently. The MINOS Far Detector was completed in August 2003 and since then has collected 2.52 kton-years of atmospheric data. Atmospheric neutrino interactions contained within the volume of the detector are separated from the dominant background from cosmic ray muons. Thirty seven events are selected with an estimated background contamination of less than 10%. Using the detector's magnetic field, 17 neutrino events and 6 anti-neutrino events are identified, 14 events have ambiguous charge. The neutrino oscillation parameters for vμ and $\\bar{v}$μ are studied using a maximum likelihood analysis. The measurement does not place constraining limits on the neutrino oscillation parameters due to the limited statistics of the data set analysed. However, this thesis represents the first observation of charge separated atmospheric neutrino interactions. It also details the techniques developed to perform atmospheric neutrino analyses in the MINOS Far Detector.

  3. Observation of relativistic electron precipitation during a rapid decrease of trapped electron flux

    Science.gov (United States)

    Millan, R. M.; Lin, R. P.; Smith, D. M.; McCarthy, M. P.; Sample, J. G.; Shprits, Y.

    2006-12-01

    Rapid depletions of the trapped electron flux are often observed, and illustrate the important role played by losses in controlling electron variability in the radiation belts. The observed decrease may be partly due to adiabatic effects, but some of the electrons are lost either through magnetopause shadowing or through precipitation into Earth's atmosphere. On January 19, 2000, duskside precipitation was observed near the start of a rapid flux depletion event, during a period of magnetic field stretching in the tail. The observations were made with the germanium spectrometer on the MAXIS balloon payload and show that real losses were occurring during the initial decrease which has previously been attributed to purely adiabatic effects. A quantitative comparison of the precipitation rate with the change in electron flux measured at GPS implies that only ~1% of the loss cone was filled, however, precipitation alone is sufficient to account for the flux decrease if it extended over 2-3 hours of local time. We present these results and compare the observed loss rate with the theoretical loss rate expected for pitch-angle scattering by EMIC waves.

  4. Solar activity impact on the Earth’s upper atmosphere

    Directory of Open Access Journals (Sweden)

    Parisi Mario

    2013-02-01

    Full Text Available The paper describes results of the studies devoted to the solar activity impact on the Earth’s upper atmosphere and ionosphere, conducted within the frame of COST ES0803 Action. Aim: The aim of the paper is to represent results coming from different research groups in a unified form, aligning their specific topics into the general context of the subject. Methods: The methods used in the paper are based on data-driven analysis. Specific databases are used for spectrum analysis, empirical modeling, electron density profile reconstruction, and forecasting techniques. Results: Results are grouped in three sections: Medium- and long-term ionospheric response to the changes in solar and geomagnetic activity, storm-time ionospheric response to the solar and geomagnetic forcing, and modeling and forecasting techniques. Section 1 contains five subsections with results on 27-day response of low-latitude ionosphere to solar extreme-ultraviolet (EUV radiation, response to the recurrent geomagnetic storms, long-term trends in the upper atmosphere, latitudinal dependence of total electron content on EUV changes, and statistical analysis of ionospheric behavior during prolonged period of solar activity. Section 2 contains a study of ionospheric variations induced by recurrent CIR-driven storm, a case-study of polar cap absorption due to an intense CME, and a statistical study of geographic distribution of so-called E-layer dominated ionosphere. Section 3 comprises empirical models for describing and forecasting TEC, the F-layer critical frequency foF2, and the height of maximum plasma density. A study evaluates the usefulness of effective sunspot number in specifying the ionosphere state. An original method is presented, which retrieves the basic thermospheric parameters from ionospheric sounding data.

  5. Computational solution of atmospheric chemistry problems

    Science.gov (United States)

    Jafri, J.; Ake, R. L.

    1986-01-01

    Extensive studies were performed on problems of interest in atmospheric chemistry. In addition to several minor projects, four major projects were performed and described (theoretical studies of ground and low-lying excited states of ClO2; ground and excited state potential energy surfaces of the methyl peroxy radical; electronic states ot the FO radical; and theoretical studies S02 (H2O) (sub n)).

  6. The Atmosphere as Laboratory: Aeronomy by Astronomy

    Science.gov (United States)

    Slanger, T. G.; Cosby, P. C.; Huestis, D. L.

    2002-01-01

    Astronomical sky spectra, which are byproducts of long-slit observations with echelle spectrographs on large telescopes, provide a unique platform for studying the optical emissions of excited molecules and atoms in the terrestrial atmosphere that can greatly extend present knowledge based on laboratory spectra. This paper summarizes some of the advances that have been made in our understanding of the lower electronic states of O2 and other species from the sky spectra and from direct observations of the Venus nightglow.

  7. Concentric-ring structures in an atmospheric pressure helium dielectric barrier discharge

    Institute of Scientific and Technical Information of China (English)

    Shang Wan-Li; Zhang Yuan-Tao; Wang De-Zhen; Sang Chao-Feng; Jiang shao-En; Yang Jia-Min; Liu shen-Ye; M.G.Kong

    2011-01-01

    This paper performs a numerical simulation of concentric-ring discharge structures within the scope of a two-dimensional diffusion-drift model at atmospheric pressure between two parallel circular electrodes covered with thin dielectric layers. With a relative high frequency the discharge structures present different appearances of ring structures within different radii in time due to the evolvement of the filaments. The spontaneous electron density distributions help understanding the formation and development of seff-organized discharge structures. During a cycle the electron avalanches are triggered by the electric field strengthened by the feeding voltage and the residual charged particles on the barrier surface deposited in the previous discharges. The accumulation of charges is shown to play a dominant role in the generation and annihilation of the discharge structures. Besides, the rings split and unify to bring and annihilate rings which form a new discharge structure.

  8. Cooling of electronic equipment

    DEFF Research Database (Denmark)

    A. Kristensen, Anders Schmidt

    2003-01-01

    Cooling of electronic equipment is studied. The design size of electronic equipment decrease causing the thermal density to increase. This affect the cooling which can cause for example failures of critical components due to overheating or thermal induced stresses. Initially a pin fin heat sink...... is considered as extruded profiles are inadequate for compact designs. An optimal pin fin shape and configuration is sought also taking manufacturing costs into consideration. Standard methods for geometrical modeling and thermal analysis are applied....

  9. The atmospheric environment--an introduction.

    Science.gov (United States)

    Jendritzky, G

    1993-09-15

    The atmosphere is part of the environment with which the human organism is permanently confronted. Epidemiological research investigates the occurrence of effects on morbidity and mortality due to heat, cold, air pollution and changes in the weather. Concentrating on aspects of the environment relevant for medical questions, three major complexes of effects can be discriminated: the complex conditions of heat exchange, the direct biological effects of solar radiation, and air pollution. Biometeorological knowledge can serve to assess the atmospheric environment, and can also be of help in the field of preventive planning, to conserve and develop the climate as a natural resource with regard to man's health, well-being and performance.

  10. Reconstruction of Atmospheric Neutrinos in Antares

    CERN Document Server

    Heijboer, Aart

    2009-01-01

    In May 2008, the Antares neutrino telescope was completed at 2.5 km depth in the Mediterranean Sea; data taking has been going on since. A prerequisite for neutrino astronomy is an accurate reconstruction of the neutrino events, as well as a detailed understanding of the atmospheric muon and neutrino backgrounds. Several methods have been developed to confront the challenges of muon reconstruction in the sea water environment, which are posed by e.g. backgrounds due to radioactivity and bioluminescence. I will discuss the techniques that allowed Antares to confidently identify its first neutrino events, as well as recent results on the measurement of atmospheric neutrinos.

  11. Lightning-driven inner radiation belt energy deposition into the atmosphere: implications for ionisation-levels and neutral chemistry

    Directory of Open Access Journals (Sweden)

    C. J. Rodger

    2007-08-01

    Full Text Available Lightning-generated whistlers lead to coupling between the troposphere, the Van Allen radiation belts and the lower-ionosphere through Whistler-induced electron precipitation (WEP. Lightning produced whistlers interact with cyclotron resonant radiation belt electrons, leading to pitch-angle scattering into the bounce loss cone and precipitation into the atmosphere. Here we consider the relative significance of WEP to the lower ionosphere and atmosphere by contrasting WEP produced ionisation rate changes with those from Galactic Cosmic Radiation (GCR and solar photoionisation. During the day, WEP is never a significant source of ionisation in the lower ionosphere for any location or altitude. At nighttime, GCR is more significant than WEP at altitudes <68 km for all locations, above which WEP starts to dominate in North America and Central Europe. Between 75 and 80 km altitude WEP becomes more significant than GCR for the majority of spatial locations at which WEP deposits energy. The size of the regions in which WEP is the most important nighttime ionisation source peaks at ~80 km, depending on the relative contributions of WEP and nighttime solar Lyman-α. We also used the Sodankylä Ion Chemistry (SIC model to consider the atmospheric consequences of WEP, focusing on a case-study period. Previous studies have also shown that energetic particle precipitation can lead to large-scale changes in the chemical makeup of the neutral atmosphere by enhancing minor chemical species that play a key role in the ozone balance of the middle atmosphere. However, SIC modelling indicates that the neutral atmospheric changes driven by WEP are insignificant due to the short timescale of the WEP bursts. Overall we find that WEP is a significant energy input into some parts of the lower ionosphere, depending on the latitude/longitude and altitude, but does not play a significant role in the neutral chemistry of the mesosphere.

  12. Atmospheric Laser Communication.

    Science.gov (United States)

    Fischer(, Kenneth W.; Witiw, Michael R.; Baars+, Jeffrey A.; Oke, T. R.

    2004-05-01

    Atmospheric laser communication, often referred to as free-space optics (FSO) or free-space laser (FSL) communication, is similar to fiber optic cable in terms of carrier wavelength and bandwidth capability, but data are transmitted directly through the atmosphere via laser beams over paths from a few meters to 4 km or longer. FSL uses lasers in the near-infrared spectrum, typically at wavelengths of 850 or 1550 nm. Given these wavelengths, atmospheric attenuation must be considered, and an adequate margin of optical power (dB) must exist to support high system availability (the percentage of time that an FSL link is in operation, typically 99.9%). A visual range of 100 m can attenuate a laser beam at a rate of nearly 130 dB km-1. For short links (rain, and snow frequently become issues. To address these issues, long-term climate data are analyzed to determine the frequency of occurrence of low visibilities and low-cloud ceilings. To estimate availability at a site of interest, adjustments to airport climate data are made to accommodate differences in altitude, geography, and the effects of the urban heat island. In sum, communication via FSL is a feasible alternative to fiber optic cable when atmospheric conditions are considered and properly analyzed.(Current affiliation: The Boeing Company, Seattle, Washington+Current affiliation: Department of Atmospheric Sciences, University of Washington, Seattle, Washington

  13. Long-term trends in the middle atmosphere dynamics at northern middle latitudes – one regime or two different regimes?

    Directory of Open Access Journals (Sweden)

    J. Lastovicka

    2010-02-01

    Full Text Available Due to increasing atmospheric concentration of greenhouse gases and changing stratospheric ozone concentration, both of anthropogenic origin, various quantities in the middle atmosphere reveal long-term changes and trends. Lastovicka and Krizan (2006 indicated possibility of change of trends in the dynamics in the northern midlatitude middle atmosphere as a whole in the 1990s. To search for such change of trends we use data on winds in the mesopause region, on total columnar ozone, on ozone laminae, on winds in the middle and lower stratosphere, and on peak electron density in the E region of the ionosphere. One group of quantities, the mesopause region wind-like trends, changes their trends around 1990, the other one, the total ozone-like trends, in the mid-1990s. Altogether they create a skeleton of scenario of the change of the middle atmosphere dynamics trends in the 1990s. Drivers of these changes appear to be different for the first group and for the second group. Tropospheric processes seem to play a role in the changes of trends in middle atmospheric dynamics.

  14. Conducting Due Diligence in China

    Institute of Scientific and Technical Information of China (English)

    CHRIS; DEVONSHIRE-ELLIS

    2008-01-01

    Ninety percent of problems when set- ting up business in China can be avoided by the deployment of due diligence at the front end of the investment planning.Here we point out some of the areas that can hinder a sensible approach to due diligence,the hidden risks and basic checks.The process does not have to be expensive. Land use rights These relate to the status of the land on which your Chinese partner has his prem-

  15. Models of magnetized neutron star atmospheres

    CERN Document Server

    Suleimanov, V; Werner, K

    2009-01-01

    We present a new computer code for modeling magnetized neutron star atmospheres in a wide range of magnetic fields (10^{12} - 10^{15} G) and effective temperatures (3 \\times 10^5 - 10^7 K). The atmosphere is assumed to consist either of fully ionized electron-ion plasmas or of partially ionized hydrogen. Vacuum resonance and partial mode conversion are taken into account. Any inclination of the magnetic field relative to the stellar surface is allowed. We use modern opacities of fully or partially ionized plasmas in strong magnetic fields and solve the coupled radiative transfer equations for the normal electromagnetic modes in the plasma. Using this code, we study the possibilities to explain the soft X-ray spectra of isolated neutron stars by different atmosphere models. In particular, the outgoing spectrum using the "sandwich" model (thin atmosphere with a hydrogen layer above a helium layer) is constructed. Thin partially ionized hydrogen atmospheres with vacuum polarization are shown to be able to improv...

  16. Atmospheric nitrogen evolution on Earth and Venus

    Science.gov (United States)

    Wordsworth, R. D.

    2016-08-01

    Nitrogen is the most common element in Earth's atmosphere and also appears to be present in significant amounts in the mantle. However, its long-term cycling between these two reservoirs remains poorly understood. Here a range of biotic and abiotic mechanisms are evaluated that could have caused nitrogen exchange between Earth's surface and interior over time. In the Archean, biological nitrogen fixation was likely strongly limited by nutrient and/or electron acceptor constraints. Abiotic fixation of dinitrogen becomes efficient in strongly reducing atmospheres, but only once temperatures exceed around 1000 K. Hence if atmospheric N2 levels really were as low as they are today 3.0-3.5 Ga, the bulk of Earth's mantle nitrogen must have been emplaced in the Hadean, most likely at a time when the surface was molten. The elevated atmospheric N content on Venus compared to Earth can be explained abiotically by a water loss redox pump mechanism, where oxygen liberated from H2O photolysis and subsequent H loss to space oxidises the mantle, causing enhanced outgassing of nitrogen. This mechanism has implications for understanding the partitioning of other Venusian volatiles and atmospheric evolution on exoplanets.

  17. Computer modeling of electron and proton transport in chloroplasts.

    Science.gov (United States)

    Tikhonov, Alexander N; Vershubskii, Alexey V

    2014-07-01

    Photosynthesis is one of the most important biological processes in biosphere, which provides production of organic substances from atmospheric CO2 and water at expense of solar energy. In this review, we contemplate computer models of oxygenic photosynthesis in the context of feedback regulation of photosynthetic electron transport in chloroplasts, the energy-transducing organelles of the plant cell. We start with a brief overview of electron and proton transport processes in chloroplasts coupled to ATP synthesis and consider basic regulatory mechanisms of oxygenic photosynthesis. General approaches to computer simulation of photosynthetic processes are considered, including the random walk models of plastoquinone diffusion in thylakoid membranes and deterministic approach to modeling electron transport in chloroplasts based on the mass action law. Then we focus on a kinetic model of oxygenic photosynthesis that includes key stages of the linear electron transport, alternative pathways of electron transfer around photosystem I (PSI), transmembrane proton transport and ATP synthesis in chloroplasts. This model includes different regulatory processes: pH-dependent control of the intersystem electron transport, down-regulation of photosystem II (PSII) activity (non-photochemical quenching), the light-induced activation of the Bassham-Benson-Calvin (BBC) cycle. The model correctly describes pH-dependent feedback control of electron transport in chloroplasts and adequately reproduces a variety of experimental data on induction events observed under different experimental conditions in intact chloroplasts (variations of CO2 and O2 concentrations in atmosphere), including a complex kinetics of P700 (primary electron donor in PSI) photooxidation, CO2 consumption in the BBC cycle, and photorespiration. Finally, we describe diffusion-controlled photosynthetic processes in chloroplasts within the framework of the model that takes into account complex architecture of

  18. Atmosphere and Ambient Space

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Atmosphere and Ambient Space This paper explores the relation between atmosphere and ambient space. Atmosphere and ambient space share many salient properties. They are both ontologically indeterminate, constantly varying and formally diffuse and they are both experienced as a subtle, non......-signifying property of a given space. But from a certain point of view, the two concepts also designate quite dissimilar experiences of space. To be ’ambient’ means to surround. Accordingly, ambient space is that space, which surrounds something or somebody. (Gibson 1987: 65) Since space is essentially...... of a surrounding character, all space can thus be described as having a fundamentally ambient character. So what precisely is an ambient space, then? As I will argue in my presentation, ambient space is a sensory effect of spatiality when a space is experienced as being particularly surrounding: a ‘space effect...

  19. Phenomenology of atmospheric neutrinos

    Directory of Open Access Journals (Sweden)

    Fedynitch Anatoli

    2016-01-01

    Full Text Available The detection of astrophysical neutrinos, certainly a break-through result, introduced new experimental challenges and fundamental questions about acceleration mechanisms of cosmic rays. On one hand IceCube succeeded in finding an unambiguous proof for the existence of a diffuse astrophysical neutrino flux, on the other hand the precise determination of its spectral index and normalization requires a better knowledge about the atmospheric background at hundreds of TeV and PeV energies. Atmospheric neutrinos in this energy range originate mostly from decays of heavy-flavor mesons, which production in the phase space relevant for prompt leptons is uncertain. Current accelerator-based experiments are limited by detector acceptance and not so much by the collision energy. This paper recaps phenomenological aspects of atmospheric leptons and calculation methods, linking recent progress in flux predictions with particle physics at colliders, in particular the Large Hadron Collider.

  20. Observations of Exoplanet Atmospheres

    CERN Document Server

    Crossfield, Ian J M

    2015-01-01

    Detailed characterization of an extrasolar planet's atmosphere provides the best hope for distinguishing the makeup of its outer layers, and the only hope for understanding the interplay between initial composition, chemistry, dynamics & circulation, and disequilibrium processes. In recent years, some areas have seen rapid progress while developments in others have come more slowly and/or have been hotly contested. This article gives an observer's perspective on the current understanding of extrasolar planet atmospheres prior to the considerable advances expected from the next generation of observing facilities. Atmospheric processes of both transiting and directly-imaged planets are discussed, including molecular and atomic abundances, cloud properties, thermal structure, and planetary energy budgets. In the future we can expect a continuing and accelerating stream of new discoveries, which will fuel the ongoing exoplanet revolution for many years to come.

  1. Atmospheres of Brown Dwarfs

    CERN Document Server

    Helling, Christiane

    2014-01-01

    Brown Dwarfs are the coolest class of stellar objects known to date. Our present perception is that Brown Dwarfs follow the principles of star formation, and that Brown Dwarfs share many characteristics with planets. Being the darkest and lowest mass stars known makes Brown Dwarfs also the coolest stars known. This has profound implication for their spectral fingerprints. Brown Dwarfs cover a range of effective temperatures which cause brown dwarfs atmospheres to be a sequence that gradually changes from a M-dwarf-like spectrum into a planet-like spectrum. This further implies that below an effective temperature of < 2800K, clouds form already in atmospheres of objects marking the boundary between M-Dwarfs and brown dwarfs. Recent developments have sparked the interest in plasma processes in such very cool atmospheres: sporadic and quiescent radio emission has been observed in combination with decaying Xray-activity indicators across the fully convective boundary.

  2. Dreaming of Atmospheres

    Science.gov (United States)

    Waldmann, Ingo

    2016-10-01

    Radiative transfer retrievals have become the standard in modelling of exoplanetary transmission and emission spectra. Analysing currently available observations of exoplanetary atmospheres often invoke large and correlated parameter spaces that can be difficult to map or constrain.To address these issues, we have developed the Tau-REx (tau-retrieval of exoplanets) retrieval and the RobERt spectral recognition algorithms. Tau-REx is a bayesian atmospheric retrieval framework using Nested Sampling and cluster computing to fully map these large correlated parameter spaces. Nonetheless, data volumes can become prohibitively large and we must often select a subset of potential molecular/atomic absorbers in an atmosphere.In the era of open-source, automated and self-sufficient retrieval algorithms, such manual input should be avoided. User dependent input could, in worst case scenarios, lead to incomplete models and biases in the retrieval. The RobERt algorithm is build to address these issues. RobERt is a deep belief neural (DBN) networks trained to accurately recognise molecular signatures for a wide range of planets, atmospheric thermal profiles and compositions. Using these deep neural networks, we work towards retrieval algorithms that themselves understand the nature of the observed spectra, are able to learn from current and past data and make sensible qualitative preselections of atmospheric opacities to be used for the quantitative stage of the retrieval process.In this talk I will discuss how neural networks and Bayesian Nested Sampling can be used to solve highly degenerate spectral retrieval problems and what 'dreaming' neural networks can tell us about atmospheric characteristics.

  3. Electron Microscopy.

    Science.gov (United States)

    Beer, Michael

    1980-01-01

    Reviews technical aspects of structure determination in biological electron microscopy (EM). Discusses low dose EM, low temperature microscopy, electron energy loss spectra, determination of mass or molecular weight, and EM of labeled systems. Cites 34 references. (CS)

  4. Exoplanet atmospheres physical processes

    CERN Document Server

    Seager, Sara

    2010-01-01

    Over the past twenty years, astronomers have identified hundreds of extrasolar planets--planets orbiting stars other than the sun. Recent research in this burgeoning field has made it possible to observe and measure the atmospheres of these exoplanets. This is the first textbook to describe the basic physical processes--including radiative transfer, molecular absorption, and chemical processes--common to all planetary atmospheres, as well as the transit, eclipse, and thermal phase variation observations that are unique to exoplanets. In each chapter, Sara Seager offers a conceptual introdu

  5. Symmetries in atmospheric sciences

    CERN Document Server

    Bihlo, Alexander

    2009-01-01

    Selected applications of symmetry methods in the atmospheric sciences are reviewed briefly. In particular, focus is put on the utilisation of the classical Lie symmetry approach to derive classes of exact solutions from atmospheric models. This is illustrated with the barotropic vorticity equation. Moreover, the possibility for construction of partially-invariant solutions is discussed for this model. A further point is a discussion of using symmetries for relating different classes of differential equations. This is illustrated with the spherical and the potential vorticity equation. Finally, discrete symmetries are used to derive the minimal finite-mode version of the vorticity equation first discussed by E. Lorenz (1960) in a sound mathematical fashion.

  6. Enhancement of two dimensional electron gas concentrations due to Si{sub 3}N{sub 4} passivation on Al{sub 0.3}Ga{sub 0.7}N/GaN heterostructure: strain and interface capacitance analysis

    Energy Technology Data Exchange (ETDEWEB)

    Dinara, Syed Mukulika, E-mail: smdinara.iit@gmail.com; Jana, Sanjay Kr.; Ghosh, Saptarsi; Mukhopadhyay, Partha; Kumar, Rahul [Advanced Technology Development Centre, Indian Institute of Technology, Kharagpur, India 721302 (India); Chakraborty, Apurba; Biswas, Dhrubes [Dept. of Electronics and Electrical Communication Engineering, Indian Institute of Technology, Kharagpur, India 721 302 (India); Bhattacharya, Sekhar [SSN Research Center, Tamilnadu, India 603110 (India)

    2015-04-15

    Enhancement of two dimensional electron gas (2DEG) concentrations at Al{sub 0.3}Ga{sub 0.7}N/GaN hetero interface after a-Si{sub 3}N{sub 4} (SiN) passivation has been investigated from non-destructive High Resolution X-ray Diffraction (HRXRD) analysis, depletion depth and capacitance-voltage (C-V) profile measurement. The crystalline quality and strained in-plane lattice parameters of Al{sub 0.3}Ga{sub 0.7}N and GaN were evaluated from double axis (002) symmetric (ω-2θ) diffraction scan and double axis (105) asymmetric reciprocal space mapping (DA RSM) which revealed that the tensile strain of the Al{sub 0.3}Ga{sub 0.7}N layer increased by 15.6% after SiN passivation. In accordance with the predictions from theoretical solution of Schrödinger-Poisson’s equations, both electrochemical capacitance voltage (ECV) depletion depth profile and C-V characteristics analyses were performed which implied effective 9.5% increase in 2DEG carrier density after passivation. The enhancement of polarization charges results from increased tensile strain in the Al{sub 0.3}Ga{sub 0.7}N layer and also due to the decreased surface states at the interface of SiN/Al{sub 0.3}Ga{sub 0.7}N layer, effectively improving the carrier confinement at the interface.

  7. Dissociative Electron Attachment

    Science.gov (United States)

    Arreola, Esmeralda; Esmeralda Arreola Collaboration; Leigh Hargreaves Collaboration

    Since the pioneering work of Boudiaffa et al., it has been understood that electrons, even with energies near or below the ionization threshold, are capable of initiating strand-breaks in human DNA. This discovery raised important questions for cancer treatments, since sub-ionizing electrons are known to be the most copiously produced secondary product of radiation therapy. But even to date these factors are largely excluded from dosimetry calculations. This lack of inclusion is, at least in part, certainly due to the dearth of fundamental data describing low-energy electron interactions with nucleotide molecules that form the basis of DNA. Understanding of how such slow electrons are able to damage DNA remains incomplete, but the strongly peaked nature of Boudiaffa et al.'s data gives strong hints at resonantly driven collision processes. DNA damage is therefore most likely driven by ``dissociative electron attachment'' (DEA). DEA is a rather complicated process to model due to the coupling of electronic and nuclear degrees of freedom in the molecule. At the California State University Fullerton, we are currently commissioning a new spectrometer to study dissociation channels, reaction rates and orientation effects in DEA collisions between slow electrons and nucleotide molecules. At the meeting we will present design parameters and commissioning data for this new apparatus.

  8. Understand electronics

    CERN Document Server

    Bishop, Owen

    2013-01-01

    Understand Electronics provides a readable introduction to the exciting world of electronics for the student or enthusiast with little previous knowledge. The subject is treated with the minimum of mathematics and the book is extensively illustrated.This is an essential guide for the newcomer to electronics, and replaces the author's best-selling Beginner's Guide to Electronics.The step-by-step approach makes this book ideal for introductory courses such as the Intermediate GNVQ.

  9. Electronic components

    CERN Document Server

    Colwell, Morris A

    1976-01-01

    Electronic Components provides a basic grounding in the practical aspects of using and selecting electronics components. The book describes the basic requirements needed to start practical work on electronic equipment, resistors and potentiometers, capacitance, and inductors and transformers. The text discusses semiconductor devices such as diodes, thyristors and triacs, transistors and heat sinks, logic and linear integrated circuits (I.C.s) and electromechanical devices. Common abbreviations applied to components are provided. Constructors and electronics engineers will find the book useful

  10. Electronic Prescribing

    Science.gov (United States)

    ... Do you prescribe electronically?” For more information about electronic prescribing, call 1-800-MEDICARE (1-800-633- ... TTY users should call 1-877-486-2048 . Electronic eRx Prescribing I went to the pharmacy, and ...

  11. STUDYING ATMOSPHERE-DOMINATED HOT JUPITER KEPLER PHASE CURVES: EVIDENCE THAT INHOMOGENEOUS ATMOSPHERIC REFLECTION IS COMMON

    Energy Technology Data Exchange (ETDEWEB)

    Shporer, Avi; Hu, Renyu [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

    2015-10-15

    We identify three Kepler transiting planets, Kepler-7b, Kepler-12b, and Kepler-41b, whose orbital phase-folded light curves are dominated by planetary atmospheric processes including thermal emission and reflected light, while the impact of non-atmospheric (i.e., gravitational) processes, including beaming (Doppler boosting) and tidal ellipsoidal distortion, is negligible. Therefore, those systems allow a direct view of their atmospheres without being hampered by the approximations used in the inclusion of both atmospheric and non-atmospheric processes when modeling the phase-curve shape. We present here the analysis of Kepler-12b and Kepler-41b atmosphere based on their Kepler phase curve, while the analysis of Kepler-7b was already presented elsewhere. The model we used efficiently computes reflection and thermal emission contributions to the phase curve, including inhomogeneous atmospheric reflection due to longitudinally varying cloud coverage. We confirm Kepler-12b and Kepler-41b show a westward phase shift between the brightest region on the planetary surface and the substellar point, similar to Kepler-7b. We find that reflective clouds located on the west side of the substellar point can explain the phase shift. The existence of inhomogeneous atmospheric reflection in all three of our targets, selected due to their atmosphere-dominated Kepler phase curve, suggests this phenomenon is common. Therefore, it is also likely to be present in planetary phase curves that do not allow a direct view of the planetary atmosphere as they contain additional orbital processes. We discuss the implications of a bright-spot shift on the analysis of phase curves where both atmospheric and gravitational processes appear, including the mass discrepancy seen in some cases between the companion’s mass derived from the beaming and ellipsoidal photometric amplitudes. Finally, we discuss the potential detection of non-transiting but otherwise similar planets, whose mass is too

  12. Sculpturing the Electron Wave Function

    CERN Document Server

    Shiloh, Roy; Lilach, Yigal; Arie, Ady

    2014-01-01

    Coherent electrons such as those in electron microscopes, exhibit wave phenomena and may be described by the paraxial wave equation. In analogy to light-waves, governed by the same equation, these electrons share many of the fundamental traits and dynamics of photons. Today, spatial manipulation of electron beams is achieved mainly using electrostatic and magnetic fields. Other demonstrations include simple phase-plates and holographic masks based on binary diffraction gratings. Altering the spatial profile of the beam may be proven useful in many fields incorporating phase microscopy, electron holography, and electron-matter interactions. These methods, however, are fundamentally limited due to energy distribution to undesired diffraction orders as well as by their binary construction. Here we present a new method in electron-optics for arbitrarily shaping of electron beams, by precisely controlling an engineered pattern of thicknesses on a thin-membrane, thereby molding the spatial phase of the electron wav...

  13. Stellar model atmospheres with magnetic line blanketing

    CERN Document Server

    Kochukhov, O; Shulyak, D

    2004-01-01

    Model atmospheres of A and B stars are computed taking into account magnetic line blanketing. These calculations are based on the new stellar model atmosphere code LLModels which implements direct treatment of the opacities due to the bound-bound transitions and ensures an accurate and detailed description of the line absorption. The anomalous Zeeman effect was calculated for the field strengths between 1 and 40 kG and a field vector perpendicular to the line of sight. The model structure, high-resolution energy distribution, photometric colors, metallic line spectra and the hydrogen Balmer line profiles are computed for magnetic stars with different metallicities and are discussed with respect to those of non-magnetic reference models. The magnetically enhanced line blanketing changes the atmospheric structure and leads to a redistribution of energy in the stellar spectrum. The most noticeable feature in the optical region is the appearance of the 5200 A depression. However, this effect is prominent only in ...

  14. Geophysical and atmospheric evolution of habitable planets.

    Science.gov (United States)

    Lammer, Helmut; Selsis, Frank; Chassefière, Eric; Breuer, Doris; Griessmeier, Jean-Mathias; Kulikov, Yuri N; Erkaev, Nikolai V; Khodachenko, Maxim L; Biernat, Helfried K; Leblanc, Francois; Kallio, Esa; Lundin, Richard; Westall, Frances; Bauer, Siegfried J; Beichman, Charles; Danchi, William; Eiroa, Carlos; Fridlund, Malcolm; Gröller, Hannes; Hanslmeier, Arnold; Hausleitner, Walter; Henning, Thomas; Herbst, Tom; Kaltenegger, Lisa; Léger, Alain; Leitzinger, Martin; Lichtenegger, Herbert I M; Liseau, René; Lunine, Jonathan; Motschmann, Uwe; Odert, Petra; Paresce, Francesco; Parnell, John; Penny, Alan; Quirrenbach, Andreas; Rauer, Heike; Röttgering, Huub; Schneider, Jean; Spohn, Tilman; Stadelmann, Anja; Stangl, Günter; Stam, Daphne; Tinetti, Giovanna; White, Glenn J

    2010-01-01

    The evolution of Earth-like habitable planets is a complex process that depends on the geodynamical and geophysical environments. In particular, it is necessary that plate tectonics remain active over billions of years. These geophysically active environments are strongly coupled to a planet's host star parameters, such as mass, luminosity and activity, orbit location of the habitable zone, and the planet's initial water inventory. Depending on the host star's radiation and particle flux evolution, the composition in the thermosphere, and the availability of an active magnetic dynamo, the atmospheres of Earth-like planets within their habitable zones are differently affected due to thermal and nonthermal escape processes. For some planets, strong atmospheric escape could even effect the stability of the atmosphere.

  15. Ionization chemistry in the H2O-dominant atmospheres of the icy moons

    Science.gov (United States)

    Shematovich, V. I.; Johnson, R. E.

    2007-08-01

    The main pathways of the ionization chemistry for pure H2O- and mixed H2O+O2+CO2+NH3+CH4 atmospheres which are representative for neutral and ionized atmospheres of the icy bodies in the Jovian and Saturnian systems are discussed. The gaseous envelopes of the icy moons of the giant planets are formed usually due to the surface radiolysis by the solar UV radiation and energetic magnetospheric plasma (Johnson, 1990). The standard astrochemical UMIST2005 (UDFA05) network is used to infer the main chemical pathways of ionization chemistry in the pure or with admixtures of other volatile molecules water vapor atmospheres. In case of the H2O- dominant atmosphere the parent H2O molecules are easily dissociated and ionized by the solar UVradiation and the energetic magnetospheric electrons. These impact processes result in the formation of the secondary neutral and ionized products - chemically active radicals O and OH, and H+, H2+, O+, OH+, and H2O+ ions. Secondary ions have admixture abundances in the H2O-dominant atmospheres, because they are efficiently transformed to H3O+ hydroxonium ions in the fast ion-molecular reactions. The major H3O+ hydroxonium ion does not chemically interact with other neutrals, and is destroyed in the dissociative recombination with thermal electrons mainly reproducing the chemically simple H, H2, O, and OH species. In case of the mixed H2O+O2-dominant atmosphere corresponding to the near-surface atmospheres of icy moons (Shematovich et al., 2005), the ionization chemistry results in the formation of the second major ion O2+ - because ion of molecular oxygen has the lower ionization potential comparing with other parent species -H2, H2O, CO2. The H+, O+, OH+, and H2O+ ions can be easily converted to O2+ ions through the ion-molecular reactions. In case of significant admixture of molecular hydrogen it is possible to transfer the O2+ ions to the O2H+ ions through the fast reaction with H2 and further to the H3O+ ions through the ion

  16. Stroke due to Hematologic Aspects

    Institute of Scientific and Technical Information of China (English)

    刘泽霖

    2004-01-01

    @@ Stroke due to ‘cerebral vein thrombosis' (CVT) is commonly used to refer to thrombosis of the cerebral venous system, including either dural venous sinuses, or deep and superficial (cortical) cerebral veins. CVT are frightening events due to the severity of their clinical manifestations and their high mortality rate (up to 30% in some casereports).The clinical signs and symptoms of CVT are relatively nonspecific: they include headache, papilledema, vomiting,seizures, focal neurological deficits (motor or sensory) and impaired consciousness. CVT has long been considered as rare and mostly infection-related event; moreover, due to its nonspecific clinical manifestations, the diagnosis has been difficult, delayed and could often be made only post mortem.

  17. Exoplanet atmosphere highlights

    Science.gov (United States)

    García Muñoz, A.

    2017-03-01

    In only two decades since the first identification of a planet outside the Solar System,and about one since the pioneering detection of an atmosphere, exoplanet science has established itself as a mature field of astrophysics. As the search of as-of-yet undiscovered planets goes on, the field is steadily expanding its focus from detection only to detection and characterization. The information to be grasped from exoplanet atmospheres provides valuable insight into the formation and evolution of the planets and, in turn, into how unique our Solar System is. Ultimately, a dedicated search for life in these distant worlds will have to deal with the information encoded in their atmospheres. In recent years there has been rapid progress on both the theoretical and observational fronts in the investigation of exoplanet atmospheres. Theorists are predicting the prevailing conditions (temperature, chemical composition, cloud occurrence, energy transport) in these objects' envelopes, and are building the frameworks with which to approach the interpretation of observables. In parallel, observers have consolidated the remote sensing techniques that were utilized during the early years, and are now venturing into techniques that hold great promise for the future. With a number of space missions soon to fly and ground-based telescopes and instruments to be commissioned, all of them conceived during the exoplanet era, the field is set to experience unprecedented progress.

  18. Modeling of Cometary Atmospheres

    Science.gov (United States)

    Gombosi, Tamas

    2004-01-01

    The NASA supported project 'Modeling of Cometary Atmospheres' has been quite successful in broadening our understanding of the cometary environment. We list peer reviewed publications and conference presentation that have been made as a result of studies performed under this project. Following the list we present details of a selection of the results.

  19. Results from atmospheric neutrinos

    Indian Academy of Sciences (India)

    J G Learned

    2000-07-01

    With the announcement of new evidence for muon neutrino disappearance observed by the super-Kamiokande experiment, the more than a decade old atmospheric neutrino anomaly moved from a possible indication for neutrino oscillations to an apparently inescapable fact. The evidence is reviewed, and new indications are presented that the oscillations are probably between muon and tau neutrinos. Implications and future directions are discussed.

  20. Basic electronics

    CERN Document Server

    Holbrook, Harold D

    1971-01-01

    Basic Electronics is an elementary text designed for basic instruction in electricity and electronics. It gives emphasis on electronic emission and the vacuum tube and shows transistor circuits in parallel with electron tube circuits. This book also demonstrates how the transistor merely replaces the tube, with proper change of circuit constants as required. Many problems are presented at the end of each chapter. This book is comprised of 17 chapters and opens with an overview of electron theory, followed by a discussion on resistance, inductance, and capacitance, along with their effects on t