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Sample records for atmospheric electrons due

  1. Park power deficit due to atmospheric stability

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose; Barthelmie, Rebecca; Ott, Søren; Larsen, Gunner Chr.

    The purpose of this paper is to present a power deficit analysis based on offshore wind farm measurements with respect to the atmospheric stability classification. The result is used to validate wind farm prediction models under different inflow and atmospheric stability conditions...

  2. Alignment of atmospheric mineral dust due to electric field

    OpenAIRE

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

    2007-01-01

    International audience 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 ch...

  3. 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...

  4. 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.

  5. Europa's Oxygen Atmosphere: Effects due to Regolith Porosity and Composition

    Science.gov (United States)

    Cassidy, T. A.; Johnson, R. E.

    2006-05-01

    The surfaces of "airless" bodies in our solar system are covered by porous regoliths, granular surfaces generated by micrometeor impact. Europa's tenuous neutral atmosphere is generated by UV and plasma irradiation of and sublimation from this regolith. Therefore, in addition to the atmosphere above the surface, there is a substantial amount of gas in the porous regolith. The effect of the regolith on the source processes and sinks are typically neglected in modeling the spatial distribution and composition of the atmosphere. The regolith complicates processes such as sputtering, the ejection of mostly neutral atoms and molecules due to energetic ion flux, because the incident ions encounter surfaces at a variety of angles, rather than one angle as usually assumed. Also, most ejecta produced within a regolith no longer have a direct line to space. If ejecta do not stick to or react with grain surfaces, then it may be safely assumed that the majority of ejecta will interact with grain surfaces before leaving the regolith. Similarly, a returning non-sticking particle experiences numerous interactions with grains below the nominal surface. As compared to a flat, smooth planetary surface, these many interactions enhance the probability of chemical reactions or sticking. F. Leblanc and R.E. Johnson have shown that the sticking coefficient is critical in describing the alkali atmosphere at Mercury and likely Europa. The regolith will also affect the velocity distribution of non-sticking ejecta and atmospheric species, which will affect the population of the Europa neutral torus. In this presentation the effect of regolith on the source and sink processes is demonstrated by generating the gravitationally bound and escaping components of the ballistic Europan atmosphere with and without regolith effects. Assuming that O2 can react in the regolith where there is a high sulfur content, we can generate a morphology roughly consistent with HST observations by McGrath and

  6. 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.

  7. 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.

  8. Alignment of atmospheric mineral dust due to electric field

    Directory of Open Access Journals (Sweden)

    Z. Ulanowski

    2007-12-01

    Full Text Available 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.

  9. Helicopter rotor noise due to ingestion of atmospheric turbulence

    Science.gov (United States)

    Simonich, J. C.; Amiet, R. K.; Schlinker, R. H.; Greitzer, E. M.

    1986-05-01

    A theoretical study was conducted to develop an analytical prediction method for helicopter main rotor noise due to the ingestion of atmospheric turbulence. This study incorporates an atmospheric turbulence model, a rotor mean flow contraction model and a rapid distortion turbulence model which together determine the statistics of the non-isotropic turbulence at the rotor plane. Inputs to the combined mean inflow and turbulence models are controlled by atmospheric wind characteristics and helicopter operating conditions. A generalized acoustic source model was used to predict the far field noise generated by the non-isotropic flow incident on the rotor. Absolute levels for acoustic spectra and directivity patterns were calculated for full scale helicopters, without the use of empirical or adjustable constants. Comparisons between isotropic and non-isotropic turbulence at the rotor face demonstrated pronounced differences in acoustic spectra. Turning and contraction of the flow for hover and low speed vertical ascent cases result in a 3 dB increase in the acoustic spectrum energy and a 10 dB increase in tone levels. Compared to trailing edge noise, turbulence ingestion noise is the dominant noise mechanism below approximately 30 rotor harmonics, while above 100 harmonics, trailing edge noise levels exceed turbulence ingestion noise by 25 dB.

  10. Runaway electron beam in atmospheric pressure discharges

    Science.gov (United States)

    Oreshkin, E. V.; Barengolts, S. A.; Chaikovsky, S. A.; Oreshkin, V. I.

    2015-11-01

    A numerical simulation was performed to study the formation of a runaway electron (RAE) beam from an individual emission zone in atmospheric pressure air discharges with a highly overvolted interelectrode gap. It is shown that the formation of a RAE beam in discharges at high overvoltages is much contributed by avalanche processes.

  11. Compensating image degradation due to atmospheric turbulence in anisoplanatic conditions

    Science.gov (United States)

    Huebner, Claudia S.

    2009-05-01

    In imaging applications the prevalent effects of atmospheric turbulence comprise image dancing and image blurring. Suggestions from the field of image processing to compensate for these turbulence effects and restore degraded imagery include Motion-Compensated Averaging (MCA) for image sequences. In isoplanatic conditions, such an averaged image can be considered as a non-distorted image that has been blurred by an unknown Point Spread Function (PSF) of the same size as the pixel motions due to the turbulence and a blind deconvolution algorithm can be employed for the final image restoration. However, when imaging over a long horizontal path close to the ground, conditions are likely to be anisoplanatic and image dancing will effect local image displacements between consecutive frames rather than global shifts only. Therefore, in this paper, a locally operating variant of the MCA-procedure is proposed, utilizing Block Matching (BM) in order to identify and re-arrange uniformly displaced image parts. For the final restoration a multistage blind deconvolution algorithm is used and the corresponding deconvolution results are presented and evaluated.

  12. Resuspension of radionuclides into the atmosphere due to forest fires

    International Nuclear Information System (INIS)

    Two major wild fire episodes occurred in north-western Russia in April/May and August 2008. The burning biomass and heating of the surface soil released several hazardous components into the atmosphere. During the spring smoke episode the 137Cs activity concentration in the air in southern Finland increased by a factor of 10 compared to values just before the episode. Simultaneously there was an increase of a same order of magnitude in the concentrations of PM10, trace metals (e.g. lead), polycyclic aromatic hydrocarbons (e.g. benzo[a]pyrene) and potassium. The 210Po/210Pb activity ratio increased from the usual 3-5% to even as high as 35% because Po is more volatile than Pb. The summer episode was less severe but still the mercury concentration in the air increased by a factor of two while 137Cs activity concentration rose by a factor of eight. From the radiological point of view the exposure to the increased radionuclide concentration was insignificant compared to health hazards due to the increased concentration of aerosol particles and their chemical components. (author)

  13. Experimental Characterization of Radiation Forcing due to Atmospheric Aerosols

    Science.gov (United States)

    Sreenivas, K. R.; Singh, D. K.; Ponnulakshmi, V. K.; Subramanian, G.

    2011-11-01

    Micro-meteorological processes in the nocturnal atmospheric boundary layer (NBL) including the formation of radiation-fog and the development of inversion layers are controlled by heat transfer and the vertical temperature distribution close to the ground. In a recent study, it has been shown that the temperature profile close to the ground in stably-stratified, NBL is controlled by the radiative forcing due to suspended aerosols. Estimating aerosol forcing is also important in geo-engineering applications to evaluate the use of aerosols to mitigate greenhouse effects. Modeling capability in the above scenarios is limited by our knowledge of this forcing. Here, the design of an experimental setup is presented which can be used for evaluating the IR-radiation forcing on aerosols under either Rayleigh-Benard condition or under conditions corresponding to the NBL. We present results indicating the effect of surface emissivities of the top and bottom boundaries and the aerosol concentration on the temperature profiles. In order to understand the observed enhancement of the convection-threshold, we have determined the conduction-radiation time constant of an aerosol laden air layer. Our results help to explain observed temperature profiles in the NBL, the apparent stability of such profiles and indicate the need to account for the effect of aerosols in climatic/weather models.

  14. Atmospheric loss of energetic electrons in the Jovian synchrotron zone

    Science.gov (United States)

    Wang, K.; Bolton, S. J.; Gulkis, S. M.; Levin, S. M.

    2002-03-01

    For decades, ground-based radio observations of Jovian synchrotron radiation have shown emission originating predominantly from the equatorial region and from high-latitude regions (lobes) near L˜2.5. The observations show a longitudinally asymmetric gap between the emission peaks of the lobes and the atmosphere of Jupiter. One possible explanation for these gaps is the loss of electrons through collisions with atmospheric neutrals as the electrons bounce along magnetic field lines and drift longitudinally in the presence of asymmetric magnetic fields. To assess this hypothesis, we applied the recently developed O6 and VIP4 magnetic field models to calculate the trajectories of electrons as they drift longitudinally in Jupiter's magnetic field, and derive the sizes of their equatorial drift loss cones. We then identified the shells on which electrons would be lost due to collisions with the atmosphere. The calculated drift loss cone sizes could be applied in future to the modeling of electron distribution functions in this region and could also be applied to the study of Jovian auroral zone. This method also allowed us to compute the shell-splitting effects for these drifting electrons and we find the shell-splitting to be small (⩽0.05 RJ). This justifies a recent modeling assumption that particles drift on the same shells in a three-dimensional distribution model of electrons. We also compared the computed gaps with the observed gaps, and found that the atmospheric loss mechanism alone is not able to sufficiently explain the observed gap asymmetry.

  15. Electron as Spatiotemporal Complexity due to Self-Organized Criticality

    OpenAIRE

    Ta-chung, Meng

    2001-01-01

    The electron, which has been pictured as an elementary particle ever since J.J. Thomson's e/m-measurement in 1897, and the relativistic motion of which is described by the Dirac equation, is discussed in the light of the recent progress made in Science of Complex Systems. Theoretical arguments and experimental evidences are presented which show that such an electron exhibits characteristic properties of spatiotemporal complexities due to Self-Organized Criticality (SOC). This implies in parti...

  16. Atmospheric pollutants and hospital admissions due to pneumonia in children

    Directory of Open Access Journals (Sweden)

    Juliana Negrisoli

    2013-12-01

    Full Text Available OBJECTIVE: To analyze the relationship between exposure to air pollutants and hospitalizations due to pneumonia in children of Sorocaba, São Paulo, Brazil. METHODS: Time series ecological study, from 2007 to 2008. Daily data were obtained from the State Environmental Agency for Pollution Control for particulate matter, nitric oxide, nitrogen dioxide, ozone, besides air temperature and relative humidity. The data concerning pneumonia admissions were collected in the public health system of Sorocaba. Correlations between the variables of interest using Pearson cofficient were calculated. Models with lags from zero to five days after exposure to pollutants were performed to analyze the association between the exposure to environmental pollutants and hospital admissions. The analysis used the generalized linear model of Poisson regression, being significant p<0.05. RESULTS: There were 1,825 admissions for pneumonia, with a daily mean of 2.5±2.1. There was a strong correlation between pollutants and hospital admissions, except for ozone. Regarding the Poisson regression analysis with the multi-pollutant model, only nitrogen dioxide was statistically significant in the same day (relative risk - RR=1.016, as well as particulate matter with a lag of four days (RR=1.009 after exposure to pollutants. CONCLUSIONS: There was an acute effect of exposure to nitrogen dioxide and a later effect of exposure to particulate matter on children hospitalizations for pneumonia in Sorocaba.

  17. 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

    2016-04-01

    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.

  18. Atmospheric electron flux at airplane altitude

    International Nuclear Information System (INIS)

    We have developed a new detector to systematically measure the cosmic-ray electron flux at airplane altitudes. We loaded a lead-glass-based electron telescope onto a commercial cargo airplane. The first experiment was carried out using the air route between Narita (Japan) and Sydney (Australia); during this flight we measured the electron flux at various altitudes and latitudes. The thresholds of the electron energies were 1, 2, and 4 GeV. The results agree with a simple estimation using one-dimensional shower theory. A comparison with a Monte Carlo calculation was made

  19. Longitudinal hot-spots in the mesospheric OH variations due to energetic electron precipitation

    Directory of Open Access Journals (Sweden)

    M. E. Andersson

    2013-07-01

    Full Text Available Using Microwave Limb Sounder (MLS/Aura and Medium Energy Proton and Electron Detector (MEPED/POES observations between 2005–2009, we study the longitudinal response of nighttime mesospheric OH to radiation belt electron precipitation. Our analysis concentrates on geomagnetic latitudes from 55–72° N/S and altitudes between 70–78 km. The aim of this study is to better assess the spatial distribution of electron forcing, which is important for more accurate modeling of its atmospheric and climate effects. In the Southern Hemisphere, OH data show a hot-spot at longitudes between 150° W–30° E, i.e., poleward of the Southern Atlantic Magnetic Anomaly (SAMA region. In the Northern Hemisphere, energetic electron precipitation–induced OH variations are more equally distributed with longitude. This longitudinal behaviour of OH can also be identified using Empirical Orthogonal Function analysis, and is found to be similar to that of MEPED–measured electron fluxes. The main difference is in the SAMA region, where MEPED appears to measure very large electron fluxes while MLS observations show no enhancement of OH. This indicates that in the SAMA region the MEPED observations are not related to precipitating electrons, at least not at energies > 100 keV, but related to instrument contamination. Analysis of selected OH data sets for periods of different geomagnetic activity levels shows that the longitudinal OH hot-spot south of the SAMA (the Antarctic Peninsula region is partly caused by strong, regional electron forcing, although atmospheric conditions also seem to play a role. This OH hot-spot is even seen weakly during periods of lower geomagnetic activity, which suggest that there is a steady drizzle of electrons affecting the atmosphere, due to the Earth's magnetic field being weaker in this region.

  20. 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......Corrosion of components and sub-assemblies on an electronic Printed Circuit Board Assembly (PCBA) is a major reliability concern. Both process and user related contamination will influence the corrosion reliability of a PCBA and the electronic device as a whole. An important process related...

  1. Electron as Spatiotemporal Complexity due to Self-Organized Criticality

    CERN Document Server

    Ta Chung Meng

    2001-01-01

    The electron, which has been pictured as an elementary particle ever since J.J. Thomson's e/m-measurement in 1897, and the relativistic motion of which is described by the Dirac equation, is discussed in the light of the recent progress made in Science of Complex Systems. Theoretical arguments and experimental evidences are presented which show that such an electron exhibits characteristic properties of spatiotemporal complexities due to Self-Organized Criticality (SOC). This implies in particular that, conceptually and logically, it is neither possible nor meaningful to identify such an object with an ordinary particle, which by definition is something that has a fixed mass (size), a fixed lifetime, and a fixed structure.

  2. Damage due to electron, ion, and x-ray lithography

    International Nuclear Information System (INIS)

    Electron, ion, and x-ray lithography are all being advocated as replacements for optical lithography at some time in the future for high-volume production of integrated circuits. Of some concern is the potential for radiation damage to underlying circuit layers caused by these lithographies. In this paper we report results of an experiment designed specifically to compare damage to radiation-hardened circuits arising from the three nonoptical lithographic technologies. We employ flood exposures of metal-oxide-semiconductor (MOS) capacitors by electrons, ions, and x rays to simulate lithographic exposures. We report results of characterizations by capacitance-voltage analysis, radiation-hardness testing, and bias-stress testing. Degradation in radiation hardness is used as measure of residual damage caused by the simulated lithographic irradiations that is not annealed out at low temperatures. We find minimal damage to the oxide resulting from lithographic doses of ions. We measure voltage shifts due to oxide- and interface-trap charge introduced by x rays and electrons and find that they can be removed by standard post-metallization anneals. We find that the radiation tolerance of MOS capacitors so irradiated and annealed is nearly identical to that of devices that did not see irradiation and annealing. Moreover, in all cases, no bias-temperature instabilities resulted from the exposure-anneal sequences. We find that all three types of lithographic techniques are promising candidates for use in advanced, radiation-hardened integrated circuit technologies

  3. Atmospheric scattering and decay of inner radiation belt electrons

    Science.gov (United States)

    Selesnick, R. S.

    2012-08-01

    The dynamics of inner radiation belt electrons are governed by competing source, loss, and transport processes. However, during the recent extended solar minimum period the source was inactive and electron intensity was characterized by steady decay. This provided an opportunity to determine contributions to the decay rate of losses by precipitation into the atmosphere and of diffusive radial transport. To this end, a stochastic simulation of inner radiation belt electron transport is compared to data taken by the IDP instrument on the DEMETER satellite during 2009. For quasi-trapped, 200 keV electrons atL= 1.3, observed in the drift loss cone (DLC), results are consistent with electron precipitation losses by atmospheric scattering alone, provided account is taken of non-diffusive wide-angle scattering. Such scattering is included in the stochastic simulation using a Markov jump process. Diffusive small-angle atmospheric scattering, while causing most of the precipitation losses, is too slow relative to azimuthal drift to contribute significantly to DLC intensity. Similarly there is no contribution from scattering by VLF plasma waves. Energy loss, energy diffusion, and azimuthal drift are also included in the model. Even so, observed decay rates of stably-trapped electrons withL diffusion with coefficient DLL ˜ 3 × 10-10 s-1 to replenish electrons lost to the atmosphere at low L values.

  4. Atmospheric Corrosion on Steel Studied by Conversion Electron Moessbauer Spectroscopy

    International Nuclear Information System (INIS)

    In order to investigate initial products on steel by atmospheric corrosion, conversion electron Moessbauer measurements were carried out at temperatures between 15 K and room temperature. From the results obtained at low temperatures, it was found that the corrosion products on steel consisted of ferrihydrite.

  5. Artificial charging of spacecraft due to electron beam emission

    International Nuclear Information System (INIS)

    Electron beams on a spacecraft can be used to simulate positive charging from energetic ions whether natural (Jovian) or artificial (particle beams). Plasma environment dependent charging effects during electron beam operations on SCATHA are discussed

  6. Electron-ion recombination study in argon at atmospheric pressure

    International Nuclear Information System (INIS)

    This study deals with a wall-stabilized arc burning in argon at atmospheric pressure. A transient mode is obtained using a fast thyristor connected to the electrodes, which short-circuits the discharge. By means of two wavelengths laser interferometry and spectroscopy measurements we have determined the temporal changes of the electron density, ground state atom density and excited atom density. We have shown that, when the electric field is suppressed, the electron temperature rapidly decreases to the gas temperature before changing electron and atom densities. This phenomenon is applied to determine the gas temperature and to evaluate the role played by ionization in electron density balance. The coefficients of ambipolar diffusion, ionization and recombination and an apparent recombination coefficient are determined versus electron temperature and compared with theoretical values

  7. 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%.

  8. 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.

  9. Electron-bombarded CCD detectors for ultraviolet atmospheric remote sensing

    Science.gov (United States)

    Carruthers, G. R.; Opal, C. B.

    1983-01-01

    Electronic image sensors based on charge coupled devices operated in electron-bombarded mode, yielding real-time, remote-readout, photon-limited UV imaging capability are being developed. The sensors also incorporate fast-focal-ratio Schmidt optics and opaque photocathodes, giving nearly the ultimate possible diffuse-source sensitivity. They can be used for direct imagery of atmospheric emission phenomena, and for imaging spectrography with moderate spatial and spectral resolution. The current state of instrument development, laboratory results, planned future developments and proposed applications of the sensors in space flight instrumentation is described.

  10. 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.

  11. Fast magnetic reconnection due to anisotropic electron pressure

    Science.gov (United States)

    Cassak, Paul; Baylor, Robert; Fermo, Raymond; Beidler, Matthew; Shay, Michael; Swisdak, Marc; Drake, James; Karimabadi, Homa

    2015-11-01

    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.

  12. Anomalous electron streaming due to electrostatic modes in tokamak plasmas

    International Nuclear Information System (INIS)

    The motion of circulating electrons in a tokamak interacting with electrostatic waves (such as lower-hybrid waves) is given by a guiding center Hamiltonian and studied by numerical integration. The unperturbed motion of electron guiding centers is first shown to be integrable, and, in a manner similar to that used in previous works, a set of action-angle coordinates for the orbits are derived which take into account finite aspect ratio and noncircular plasma cross section. Electrostatic modes in the low-frequency, long-wavelength limit are treated as a perturbation to the guiding center Hamiltonian. The waves are generated with low integral values of the toroidal and poloidal mode numbers n and m and satisfy the approximate lower-hybrid dispersion relation kperpendicular/kparallel ∼ ωpe/ω ∼ 101.5. If the number of modes is greater than three, the electron motion parallel to the magnetic field is observed to be stochastic in the phase-space region where vparallel is near the wave parallel phase velocity. On surfaces with rational values of the safety factor q, superposition of modes with degenerate values of the parallel mode number n + (m/q) is shown to result in electron streaming perpendicular to the magnetic field. The speed and direction of this radial motion are observed to have sinusoidal dependence on the poloidal angle. For models including finite magnetic-field shear, the authors find a limit to the extent of the radial streaming of the electrons. Results for the speed of the electron radial motion for typical tokamak parameters are presented

  13. Degradation of the surface of a metasilicate glass due to atmosphere moisture

    Directory of Open Access Journals (Sweden)

    Ziemath Ervino Carlos

    1998-01-01

    Full Text Available Glasses with low silica content are very susceptible to suffer pronounced degradation when exposed to room atmosphere during short times. In this work the results of the degradation of the surface of a metasilicate glass with composition 2Na2O.1CaO.3SiO2 are presented. Optical and scanning electron microscopy observations, X-ray diffraction, infrared and Raman microprobe spectroscopic measurements of the modified surface of this glass show strong evidences that it is formed essentially by a crystalline carbonate layer.

  14. Confinement of superconducting fluctuations due to emergent electronic inhomogeneities

    OpenAIRE

    Carbillet, C.; Caprara, S.; Grilli, M.; Brun, C; Cren, T; Debontridder, F.; Vignolle, B.; Tabis, W.; Demaille, D.; Largeau, L.; Ilin, K.; Siegel, M.; Roditchev, D.; Leridon, B.

    2015-01-01

    The microscopic nature of an insulating state in the vicinity of a superconducting state, in the presence of disorder, is a hotly debated question. While the simplest scenario proposes that Coulomb interactions destroy the Cooper pairs at the transition, leading to localization of single electrons, an alternate possibility supported by experimental observations suggests that Cooper pairs instead directly localize. The question of the homogeneity, granularity, or possibly glassiness of the mat...

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

    Science.gov (United States)

    Ohta, I. S.; Akimune, H.; Fukushima, M.; Ikeda, D.; Inome, Y.; Matthews, J. N.; Ogio, S.; Sagawa, H.; Sako, T.; Shibata, T.; Yamamoto, T.

    2016-02-01

    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 1018 eV air shower was estimated to be 3.96×10-16 W m-2 Hz-1 with a 95% confidence level.

  16. Depletion of total ozone content of the atmosphere due to solar particle events

    International Nuclear Information System (INIS)

    The depletion of total ozone in the atmosphere due to major solar particle events during the past decade and a half is investigated. The daily data for a number of stations situated above 40deg N for several days before and after each particle event, are analyzed and superimposed. The seasonal variation is taken into consideration and corrected for. The percentage variation curves for a number of particle events are superimposed to obtain a consolidated curve which shows a detectable depletion of ozone after such occurrences. The depletion of ground ozone due to extra-terrestrial energetic particles has not been definitely identified before. The percentage reduction of O3 so obtained agrees well with observed Nimbus-4 satellite data of 3.3% after 8 days of 4 Aug. 1972 event. Different mechanisms of ozone depletion due to particle flux are discussed. (auth.)

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

    Science.gov (United States)

    Komarov, S. V.; Khabibullin, I. I.; Churazov, E. M.; Schekochihin, A. A.

    2016-09-01

    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 ˜0.1 per cent at energies ≳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 scales, which are impossible to resolve spatially. The absence of the effect at the predicted level may set a lower limit on the electron collisionality in the ICM. At the same time, the small value of the effect implies that it does not preclude the use of clusters as (unpolarized) calibration sources for X-ray polarimeters at this level of accuracy.

  18. 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 ...

  19. 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.

  20. 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...

  1. Polarization of circumstellar bow shocks due to electron scattering

    Science.gov (United States)

    Shrestha, Manisha; Hoffman, J. L.; Neilson, H.; Ignace, R.

    2014-01-01

    Circumstellar material (CSM) provides a link between interacting supernovae and their massive progenitor stars. This CSM arises from stellar winds, outflows, or eruptions from a massive star before it explodes and can be detected around stars or supernovae with polarimetric observations. We use a Monte Carlo based radiative transfer code (SLIP) to investigate the polarization created by different models for the CSM surrounding a central source such as supernovae or massive stars. We vary parameters such as the shape, optical depth, temperature, and brightness of the CSM and compare the simulated flux and polarization behavior with observational data. We present results from new simulations that assume a bow shock shape for the CSM. Bow shocks are commonly observed around massive stars; this shape forms when a star moving more quickly than the speed of sound in the local interstellar medium emits a stellar wind that drives a shock wave into the ISM. Since a bow shock projects an aspherical shape onto the sky, light from the central source that scatters in the shock region becomes polarized. We present electron-scattering polarization maps for this geometry and discuss the behavior of observed polarization with viewing angle in the unresolved case.

  2. 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.

  3. Confinement of superconducting fluctuations due to emergent electronic inhomogeneities

    Science.gov (United States)

    Carbillet, C.; Caprara, S.; Grilli, M.; Brun, C.; Cren, T.; Debontridder, F.; Vignolle, B.; Tabis, W.; Demaille, D.; Largeau, L.; Ilin, K.; Siegel, M.; Roditchev, D.; Leridon, B.

    2016-04-01

    The microscopic nature of an insulating state in the vicinity of a superconducting state in the presence of disorder is a hotly debated question. While the simplest scenario proposes that Coulomb interactions destroy the Cooper pairs at the transition, leading to localization of single electrons, an alternate possibility supported by experimental observations suggests that Cooper pairs instead directly localize. The question of the homogeneity, granularity, or possibly glassiness of the material on the verge of this transition is intimately related to this fundamental issue. Here, by combining macroscopic and nanoscale studies of superconducting ultrathin NbN films, we reveal nanoscopic inhomogeneities that emerge when the film thickness is reduced. For the thinnest films, scanning tunneling spectroscopy at low temperature unveils inhomogeneities in the superconducting properties, of typical size Li, that are not correlated to any structural inhomogeneity and that are found to persist above the critical temperature in the form of a pseudogap. Remarkably enough, while the thickest films display a purely two-dimensional behavior in the superconducting fluctuations above the critical temperature, paraconductivity in the pseudogap regime of the thinnest samples demonstrates fluctuations of the amplitude of the order parameter, corresponding to zero-dimensional fluctuating regions of size precisely Li. We propose that an anomalous diffusion slowing-down process is at play at long wave vectors, leading to some "confinement" of the superconducting fluctuations, which allows us to explain the simultaneous paradoxical presence of a pseudogap and zero-dimensional amplitude fluctuations of the order parameter. These findings call for further theoretical investigation to understand this intermediate state where Cooper pairs continuously evolve from a bound state of fermionic objects into localized bosonic entities.

  4. 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.

  5. Electron densities and alkali atoms in exoplanet atmospheres

    CERN Document Server

    Lavvas, Panayotis; Yelle, Roger V

    2014-01-01

    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 209458 b, 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-2 b 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 cl...

  6. Atmospheric electron neutrinos in the MINOS far detector

    Energy Technology Data Exchange (ETDEWEB)

    Speakman, Benjamin Phillip; /Minnesota U.

    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{sup data}{sub trk/shw}/R{sup MC}{sub trk/shw} = 0.74{sup +0.12}{sub -01.0}(stat.) {+-} 0.04 (syst.) This double ratio should be equal to unity in the absence of

  7. POES SEM-2 observations of radiation belt dynamics and energetic electron precipitation in to the atmosphere

    International Nuclear Information System (INIS)

    Complete text of publication follows. The coupling of the Van Allen radiation belts to the Earth's atmosphere through the effects of precipitating particles is an area of intense scientific interest. Currently, there are significant uncertainties surrounding the precipitating characteristics of medium energy electrons (>20 keV), and even more uncertainties for relativistic electrons. In this paper we examine roughly ten-years of measurements of trapped and precipitating electrons available from the Polar Orbiting Environmental Satellites (POES)/Space Environment Monitor (SEM-2) which has provided long-term global data in this energy range. Relativistic electron increases are associated with both interplanetary Coronal Mass Ejections (ICMEs) and periodic high speed solar wind streams (HSSWS). The processes triggered by ICMEs are roughly twice as effective at enhancing POES-observed electrons to relativistic energies as the processes triggered by HSSWS. We find that ICME-associated increases can extend down to L∼2, while other enhancements are generally limited to L>3.5. Finally, during HSSWS conditions there is an energy-dependent time delay observed in the POES/SEM-2 observations, with the >800 keV relativistic electron enhancement delayed by ∼1-week relative to the >30 keV electron enhancement, probably due to the timescales of the acceleration processes. One possible interpretation of this is a two-stage process, where relatively rapid acceleration initially takes place near the geomagnetic equator as predicted by theory and observed experimentally. This is followed by a much slower process, where the relativistic electrons scatter towards the atmosphere loss cone at a rate which is energy dependent. Such large delays should have consequences for the timing of the atmospheric impact of HSSWS-triggered geomagnetic storms.

  8. Cross Sections for Electron Impact Excitation of Ions Relevant to Planetary Atmospheres Observation

    Science.gov (United States)

    Tayal, Swaraj S.

    1998-01-01

    The goal of this research grant was to calculate accurate oscillator strengths and electron collisional excitation strengths for inelastic transitions in atomic species of relevance to Planetary Atmospheres. Large scale configuration-interaction atomic structure calculations have been performed to obtain oscillator strengths and transition probabilities for transitions among the fine-structure levels and R-matrix method has been used in the calculations of electron-ion collision cross sections of C II, S I, S II, S III, and Ar II. A number of strong features due to ions of sulfur have been detected in the spectra of Jupiter satellite Io. The electron excitation cross sections for the C II and S II transitions are studied in collaboration with the experimental atomic physics group at the Jet Propulsion Laboratory. There is excellent agreement between experiment and theory which provide an accurate and broad-base test of the ability of theoretical methods used in the calculation of atomic processes. Specifically, research problems have been investigated for: electron impact excitation cross sections of C II: electron impact excitation cross sections of S III; energy levels and oscillator strengths for transitions in S III; collision strengths for electron collisional excitation of S II; electron impact excitation of inelastic transitions in Ar II; oscillator strengths of fine-structure transitions in neutral sulfur; cross sections for inelastic scattering of electrons from atomic nitrogen; and excitation of atomic ions by electron impact.

  9. Effects of Plasma Drag on Low Earth Orbiting Satellites due to Heating of Earth's Atmosphere by Coronal Mass Ejections

    OpenAIRE

    Nwankwo, Victor U. J.; Chakrabarti, Sandip K.

    2013-01-01

    Solar events, such as coronal mass ejections (CMEs) and solar flares, heat up the upper atmosphere and near-Earth space environment. Due to this heating and expansion of the outer atmosphere by the energetic ultraviolet, X-ray and particles expelled from the sun, the low Earth-Orbiting satellites (LEOS) become vulnerable to an enhanced drag force by the ions and molecules of the expanded atmosphere. Out of various types of perturbations, Earth directed CMEs play the most significant role. The...

  10. Differential pumping system for electron beam extraction in atmosphere

    International Nuclear Information System (INIS)

    The design of a differential pumping system (DPS) for extraction of an electron beam from the shaping region with a pressure of approximately 10-5 torr into the atmosphere is described. The system consists of five sections, with individual vacuum pumping. To reduce the dimensions of DPS the first three sections are pumped out through intermediate volumes connected to vapour-oil pumps. At the DPS outlet, a diaphragm with a small opening is replaced by an air ejector, which considerably improves the operation of DPS and makes it possible to increase the opening in the outlet diaphragm to 4-6 mm. The pressure in the DPS sections has been calculated, and the results are confirmed by experimental data

  11. Trust and Risk in Business Networks: Towards a Due Diligence for Electronic Commerce

    OpenAIRE

    Fritz, Melanie

    2006-01-01

    This paper develops a due diligence for electronic transactions with new partners in business networks with complex goods such as food products to enable the use of e-commerce potentials in first time transactions. The e-commerce due diligence is a means to reduce perceived risks and uncertainties for businesses and create trust and confidence in the electronic transaction with appropriate information. The paper presents a conceptual framework for the due diligence integrating the principles ...

  12. 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.

  13. Atmospheric entry of Mars-return nuclear-powered vehicles due to accidental termination of operations

    Science.gov (United States)

    Menees, Gene P.; Park, Chul

    1993-06-01

    The entry of nuclear reactors into Earth's atmosphere resulting from an accidental or inadvertent abort of a space vehicle powered by nuclear-thermal rockets is investigated. The study is made for a typical piloted Mars mission vehicle incapacitated by an accident or malfunction during the Earth-arrival phase of the Mars-return journey due to simultaneous, multiple failures of its component systems. A single accident/abort scenario resulting in three entry possibilities is considered for a nominal hyperbolic in-bound approach velocity of 8 km/sec. The most severe case involving a direct entry is then analyzed over a broad range of approach velocities extending to 12 km/sec to include sprint-type missions. The results indicate that the severe surface heating, stagnation pressures, and g-loads are greater than 150 kW/sq cm, 300 atm, and 800-g, respectively. The wall heat transfer rate exceeds the value that can be accommodated by a carbon heatshield through radiation equilibrium prior to sublimation at 5500 K. These conditions are beyond our previous experience in crew safety, structural design, and thermal protection.

  14. Large-scale changes of the atmosphere (climate), geodynamics and biosphere due to the galactic shocks

    Science.gov (United States)

    Khristoforova, D.

    2009-04-01

    The Solar system periodically passes through spiral arms of the Galaxy, which are stellar density waves. Processes due to the presence of galactic shocks (shock waves) may be responsible for the abrupt atmosphere changes (climate), geodynamics (supercontinental cycle, large tectonic processes, mantle convection, geomagnetic field and others) and biosphere. Galactic shocks (GS) are the narrow region of high gas compression along the inner edge of spiral wave. Shock wave leads to the interstellar dust compression and to the phase transition in the interstellar gas. GS are large-scale trigger mechanism of active star formation. GS ultimately changes temperature, pressure and the radiation balance. It is quite surprisingly that majority of the "data points" of the geochronological and stratigraphic scales are closely related to the time moments when the Solar system has passed through the galactic shocks. This extraterrestrial cause for the change of physical and chemical conditions on the Earth had profound effects on the biologic extinction and explosions. This hypothesis explains the biologic explosion in Cambrian, the Permian - Triassic and Cretaceous-Tertiary extinctions, i.e., the beginning of Paleozoic, Mesozoic and Cenozoic. It is valid in the frame of galactic shock model that any discussion time estimates of these past events and their implications for the future must be quantitative. It will permit an evaluation of age of greater catastrophes and changes in the Earth history, of the future meets with the spiral arms of the Galaxy. It predicts the existence of chronological scales of other planets.

  15. Electronic pairing mechanism due to band modification in a two-band model: Tc evaluation

    International Nuclear Information System (INIS)

    Following the electronic model developed by us previously (Mizia and Romanowski, Mizia) we estimate the superconducting transition temperature in a simple electronic two-band model for materials characterized by a broad superconducting band and a narrow level within the same energy range. A large electron deformation coupling constant and large electron correlation effects are assumed. It is shown that high-temperature superconductivity is entirely possible within a range of reasonable electronic parameters. This model does not assume any artificial interactions to obtain a negative pairing potential. Instead, the negative part of the electronic interaction potential comes from the modification of the electron dispersion relation with growing number of superconducting pairs. Such a modification is possible in soft electronic systems, i.e. in systems partial to band modification due to large internal stresses, strong electronic correlation effects and broad band narrow level charge transfer during the superconducting transition. (orig.)

  16. Assessment of thyroid doses due to 131I from atmospheric nuclear weapons tests in Nevada

    International Nuclear Information System (INIS)

    About 100 of the atmospheric nuclear weapons tests carried out at the Nevada Test Site (NTS) resulted in off-site detection of radioactive materials. These tests released about 5 EBq of 131I in the atmosphere, predominantly in 1952, 1953, 1955 and 1957. Radioiodine was deposited across the United States of America, with the highest values immediately downwind of the NTS and the lowest values of the west coast. In the 1980s, three major dose reconstruction studies were undertaken in order to address the assessment of thyroid doses due to 131I fallout from the NTS: (1) the ORERP study of the US Department of Energy; (2) the Utah thyroid cohort study; and (3) the NCI thyroid study. The first two studies are concerned with doses received by 'local' populations (less than 800 km from the NTS), while the third study deals with the estimation of thyroid doses received by populations across the continental USA. In all three studies, uncertainty estimates were attached to the calculated doses. The second and third studies specifically addressed the assessment of thyroid doses from radioiodines, whereas the first study has a much wider scope, in that it considers both external and internal irradiation of the main organs and tissues of the body from all radionuclides produced by nuclear weapons tests. The thyroid doses from NTS fallout resulted essentially from the ingestion of milk contaminated with 131I; other, usually less important, pathways of exposure are the consumption of leafy vegetables and eggs. Because children generally drink more milk than adults, and because of the smaller mass of their thyroid gland, children received higher doses than adults for a given deposition of 131I. The thyroid doses are estimated to have ranged up to a few grays for small children in south-western Utah who drank milk from a family owned goat. A preliminary estimate of the collective thyroid dose to the US population from NTS fallout is 4 x 106 man·Gy, corresponding to a per capita

  17. Radio Tomography of Ionospheric Structures (probably) due to Underground-Surface-Atmosphere-Ionosphere Coupling

    Science.gov (United States)

    Kunitsyn, V.; Nesterov, I.; Andreeva, E.; Rekenthaler, D. A.

    2012-12-01

    Ionospheric radio-tomography (RT) utilizes radio signals transmitted from the global navigational satellite systems (GNSS), including low-orbiting (LO) navigational systems such as Transit, Tsikada, etc., and high-orbiting (HO) navigational systems such as GPS, GLONASS, Galileo, Beidou, etc. The signals that are transmitted from the LO navigational satellites and recorded by ground receiving chains can be inverted for almost instantaneous (5-8 min) 2D snapshots of electron density. The data from the networks of ground receivers that record the signals of the HO satellites are suitable for implementing high-orbital RT (HORT), i.e. reconstructing the 4D distributions of the ionospheric electron density (one 3D image every 20-30 min). In the regions densely covered by the GNSS receivers, it is currently possible to get a time step of 2-4 min. The LORT and HORT approaches have a common methodical basis: in both these techniques, the integrals of electron density along the ray between the satellite and the receiver are measured, and then the tomographic procedures are applied to reconstruct the distributions of electron density. We present several examples of the experiments on the ionospheric RT, which are related to the Underground-Surface-Atmosphere-Ionosphere (USAI) coupling. In particular, we demonstrate examples of RT images of the ionosphere after industrial explosions, rocket launches, and modification of the ionosphere by high-power radio waves. We also show RT cross sections reflecting ionospheric disturbances caused by the earthquakes (EQ) and tsunami waves. In these cases, there is an evident cause-and-effect relationship. The perturbations are transferred between the geospheres predominantly by acoustic gravity waves (AGW), whose amplitudes increase with increasing height. As far as EQ are concerned, the cause of the USAI coupling mechanism is not obvious. It is clear, however, that the regular RT studies can promote the solution of this challenging problem

  18. Mega-heatwave temperatures due to combined soil desiccation and atmospheric heat accumulation

    Science.gov (United States)

    Miralles, Diego G.; Teuling, Adriaan J.; van Heerwaarden, Chiel C.; Vilà-Guerau de Arellano, Jordi

    2014-05-01

    The recent European mega-heatwaves of 2003 and 2010 broke temperature records across Europe. Although events of this magnitude were unprecedented from a historical perspective, they are expected to become common by the end of the century. However, our understanding of extreme heatwave events is limited and their representation in climate models remains imperfect. Here we investigate the physical processes underlying recent mega-heatwaves using satellite and balloon measurements of land and atmospheric conditions from the summers of 2003 in France and 2010 in Russia, in combination with a soil-water-atmosphere model. We find that, in both events, persistent atmospheric pressure patterns induced land-atmosphere feedbacks that led to extreme temperatures. During daytime, heat was supplied by large-scale horizontal advection, warming of an increasingly desiccated land surface and enhanced entrainment of warm air into the atmospheric boundary layer. Overnight, the heat generated during the day was preserved in an anomalous kilometres-deep atmospheric layer located several hundred metres above the surface, available to re-enter the atmospheric boundary layer during the next diurnal cycle. This resulted in a progressive accumulation of heat over several days, which enhanced soil desiccation and led to further escalation in air temperatures. Our findings suggest that the extreme temperatures in mega-heatwaves can be explained by the combined multi-day memory of the land surface and the atmospheric boundary layer.

  19. Superficial violation of the Pauli principle due to the possible substructure of electrons

    International Nuclear Information System (INIS)

    Superficial violation of the Pauli principle due to the possible substructure of electrons is discussed in composite models of quarks and leptons. The ratio of the Pauli forbidden atomic transition to the allowed one is estimated to be of order 10-50--10-44 for heavy atoms if the size of the electron is of order 10-17 cm

  20. 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...

  1. Influence of low energy hadron interaction models on atmospheric ionisation due to cosmic ray heavy nuclei

    International Nuclear Information System (INIS)

    Results from recent atmospheric cascade simulations with CORSIKA 6.990 code using GHEISHA2002, FLUKA 2011 and QGSJET II hadron generators are presented. The energy deposit in air by various cosmic ray nuclei is computed. Primary Helium, Carbon, Oxygen and Iron nuclei are considered as primaries. The simulations are performed in a wide energy range between 1GeV/nucleon and 100 GeV/nucleon. A realistic curved atmospheric model is assumed, parameterised according to US standard atmosphere. The ion pair production in the atmosphere considering the contribution of different cascade components, namely electromagnetic, muon and hadron is obtained. The yield function Y for total ionisation is compared for the different models. In addition, the Y functions are compared for different geomagnetic rigidity cut-offs, namely 1 GV (polar caps), 5 GV (middle latitudes - i.e. Bulgaria), 9 GV (lower middle latitudes) and 15 GV (equatorial regions). The observed differences are widely discussed and a comparison with experimental data is performed. Several applications are mentioned as well. Key words: cosmic rays, ionisation model, hadron interaction models, atmosphere

  2. 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 ...

  3. Simulation of Electron-Beam Generating Plasma at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    OUYANG Liang; LI Hong; LI Benben; ZHOU Junqing; YAN Hong; SU Tie; WANG Huihui; LIUWandong

    2007-01-01

    As electron-beam generating plasma is widely applied,the software tool EGS4(Electron-Gamma Shower) was used to simulate the transmission and energy deposition of electron-beam in air.The simulation results indicated that the range of the electron-beam was inversely proportional to the gas pressure in a wide range of gas pressure,and the electron-beam of 200 keV could generate a plasma with a density 1011 cm-3 in air of latm.In addition,the energy distribution of the beam-electron and plasma density profile produced by the beam were achieved.

  4. Patterning of graphene for flexible electronics with remote atmospheric-pressure plasma using dielectric barrier

    Science.gov (United States)

    Kim, Duk Jae; Park, Jeongwon; Geon Han, Jeon

    2016-08-01

    We show results of the patterning of graphene layers on poly(ethylene terephthalate) (PET) films through remote atmospheric-pressure dielectric barrier discharge plasma. The size of plasma discharge electrodes was adjusted for large-area and role-to-role-type substrates. Optical emission spectroscopy (OES) was used to analyze the characteristics of charge species in atmospheric-pressure plasma. The OES emission intensity of the O2* peaks (248.8 and 259.3 nm) shows the highest value at the ratio of \\text{N}2:\\text{clean dry air (CDA)} = 100:1 due to the highest plasma discharge. The PET surface roughness and hydrophilic behavior were controlled with CDA flow rate during the process. Although the atmospheric-pressure plasma treatment of the PET film led to an increase in the FT-IR intensity of C–O bonding at 1240 cm‑1, the peak intensity at 1710 cm‑1 (C=O bonding) decreased. The patterning of graphene layers was confirmed by scanning electron microscopy and Raman spectroscopy.

  5. The Formation of Stable Components in the Atmosphere due to Energy Production

    OpenAIRE

    Antonovsky, M.Y.

    1988-01-01

    This paper is devoted to the possibility of taking into account the pressures of human activity on the atmosphere. It was presented at the International Workshop Envrisk '88 "Energy and Environment: the European Perspective on Risk" organized by the Italian Commission for Nuclear and Alternative Energy Sources, May 1988.

  6. Intensity of Upward Muon Flux Due to Cosmic-Ray Neutrinos Produced in the Atmosphere

    Science.gov (United States)

    Lee, T. D.; Robinson, H.; Schwartz, M.; Cool, R.

    1963-06-01

    Calculations were performed to determine the upward going muon flux leaving the earth's surface after production by cosmic-ray neutrinos in the crust. Only neutrinos produced in the earth's atmosphere are considered. Rates of the order of one per 100 sq m/day might be expected if an intermediate boson exists and has a mass less than 2 Bev. (auth)

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

    OpenAIRE

    Boehm, Celine; Lavalle, Julien

    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 (and 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 scatterin...

  8. Secondary electron emission due to Auger de-excitation of metastable nitrogen molecules at metallic surfaces

    OpenAIRE

    Marbach, J.; Bronold, F. X.; Fehske, H.

    2011-01-01

    With an eye on plasma walls we investigate, within an effective model for the two active electrons involved in the process, secondary electron emission due to Auger de-excitation of metastable nitrogen $N_2(^3\\sigma^+_u)$ molecules at metallic surfaces. Modelling bound and unbound molecular states by a LCAO approach and a two-center Coulomb wave, respectively, and the metallic states by the eigenfunctions of a step potential we employ Keldysh Green's functions to calculate the secondary elect...

  9. 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....

  10. 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.

  11. Magneto-oscillations due to electron-electron interactions in the ac conductivity of a 2D electron gas

    OpenAIRE

    Sedrakyan, T. A.; Raikh, M. E.

    2007-01-01

    Electron-electron interactions give rise to the correction, \\delta\\sigma^{int}(\\omega), to the ac magnetoconductivity, \\sigma(\\omega), of a clean 2D electron gas that is periodic in \\omega_c^{-1}, where \\omega_c is the cyclotron frequency. Unlike conventional harmonics of the cyclotron resonance, which are periodic with \\omega, this correction is periodic with \\omega^{3/2}. Oscillations in \\delta\\sigma^{int}(\\omega) develop at low magnetic fields, \\omega_c\\ll\\omega, when the conventional harm...

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

    OpenAIRE

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

    2014-01-01

    Oceanic tsunami waves couple with atmospheric gravity waves, as previously observedthrough 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 Tohoku-Oki tsunami propagation. High-frequency perturbations of these parameters are observed during three expected crossings of the tsunami-generated gravity waves by the GOCE satellite. From theore...

  13. Recent Northern Hemisphere stratospheric HCl increase due to atmospheric circulation changes

    OpenAIRE

    Mahieu, Emmanuel; M. P. Chipperfield; Notholt, J.; T. Reddmann; J. Anderson; Bernath, P. F.; Blumenstock, T.; M. T. Coffey; S. S. Dhomse; W. Feng; Franco, Bruno; Froidevaux, L.; D. W. T. Griffith; Hannigan, J.W.; F. Hase

    2014-01-01

    The abundance of chlorine in the Earth’s atmosphere increased considerably during the 1970s to 1990s, following large emissions of anthropogenic long-lived chlorine-containing source gases, notably the chlorofluorocarbons. The chemical inertness of chlorofluorocarbons allows their transport and mixing throughout the troposphere on a global scale[1], before they reach the stratosphere where they release chlorine atoms that cause ozone depletion[2]. The large ozone loss over Antarctica[3] was t...

  14. Failure Analysis of a Nickel-Plated Electronic Connector Due to Salt-Induced Corrosion (ENGE 2014).

    Science.gov (United States)

    Lee, Na-Ri; Choi, Hyoung-Seuk; Choi, Duck-Kyun

    2015-10-01

    When electronic connectors in mobile devices are miniaturized, the thickness of plating decreases. However, this thin plating is expected to decrease the life of the connector due to problems with corrosion. In this study, salt spray aging tests were performed on miniaturized nickel-plated stainless steel electronic connectors to observe failure mechanisms in realistic environments. The tests were performed three times using a 5% NaCl solution in an atmosphere of 45 °C; each test included several cycles where one cycle was one 24-h period consisting of 8 h of salt spray and 16 h without salt spray. The nickel-plating layers were periodically observed by electron probe X-ray micro-analyzer, wavelength dispersive spectroscopy, and field-emission scanning electron microscopy to analyze and identify the corrosion mechanism. We found that the primary failure mode of the nickel plating is blistering and delamination. The corrosion mechanism is typically a chain reaction of several corrosion mechanisms: pitting corrosion --> stress corrosion cracking --> hydrogen-induced cracking --> blistering and delamination. Finally, we discuss countermeasures to prevent corrosion of the nickel layer based on the corrosion mechanisms identified in this study. PMID:26726358

  15. 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.

  16. Assessment of toxicity in waters due to heavy metals derived from atmospheric deposition using Vibrio fischeri.

    Science.gov (United States)

    Cukurluoglu, Sibel; Muezzinoglu, Aysen

    2013-01-01

    Water toxicity originating from the atmospheric deposition of six heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) was investigated on Vibrio fischeri activity in Izmir, Turkey. A LUMIStox® test was applied to dry and wet deposition samples and metal solutions. The inhibition levels and effective toxicity concentrations of these samples and solutions were determined. Interactive toxicity effects among the metals were investigated. When the impacts of the synthetic single heavy metal solutions were compared with each other, a toxicity ranking of Cr>Cd>Pb>Cu>Zn>Ni was obtained in order of decreasing severity. The total effective concentrations of these six metals were in the ranges of 0.074-0.221 mg/L and 0.071-0.225 mg/L for receiving aqueous solutions of dry and wet atmospheric depositions, respectively. The toxicity data showed that the wet deposition samples were 15% more toxic than the dry deposition samples. The interactive toxicity effects of the heavy metals in both dry and wet deposition samples were classified as antagonistic. High levels of heavy metals deposited in dissolved form may constitute an important input in the biochemical cycle and may have significant impacts. PMID:23030388

  17. Reconstruction of 131I radioactive contamination dynamics in belarus due to Chernobyl accident using atmospheric transport modelling

    International Nuclear Information System (INIS)

    The calculations of 131I radioactive contamination in the 3 most contaminated regions of Belarus are carried out using the Lagrangian-Eulerian atmospheric transport LEDI model. Verification of the obtained results is made on the base of 131I activity measurements in soil of 534 settlements in Belarus during the initial period of the accident. The input of radionuclides wet deposition processes due to rains and fogs has been evaluated in the period of radioactivity releases from the Chornobyl NPP.

  18. A case study of electron precipitation fluxes due to plasmaspheric hiss

    Science.gov (United States)

    Hardman, Rachael; Clilverd, Mark A.; Rodger, Craig J.; Brundell, James B.; Duthie, Roger; Holzworth, Robert H.; Mann, Ian R.; Milling, David K.; Macusova, Eva

    2015-08-01

    We find that during a large geomagnetic storm in October 2011 the trapped fluxes of >30, >100, and >300 keV outer radiation belt electrons were enhanced at L = 3-4 during the storm main phase. A gradual decay of the trapped fluxes was observed over the following 5-7 days, even though no significant precipitation fluxes could be observed in the Polar Orbiting Environmental Satellite (POES) electron precipitation detectors. We use the Antarctic-Arctic Radiation-belt (Dynamic) Deposition-VLF Atmospheric Research Konsortium receiver network to investigate the characteristics of the electron precipitation throughout the storm period. Weak electron precipitation was observed on the dayside for 5-7 days, consistent with being driven by plasmaspheric hiss. Using a previously published plasmaspheric hiss-induced electron energy e-folding spectrum of E0 = 365 keV, the observed radio wave perturbation levels at L = 3-4 were found to be caused by >30 keV electron precipitation with flux ~100 el cm-2 s-1 sr-1. The low levels of precipitation explain the lack of response of the POES telescopes to the flux, because of the effect of the POES lower sensitivity limit and ability to measure weak diffusion-driven precipitation. The detection of dayside, inner plasmasphere electron precipitation during the recovery phase of the storm is consistent with plasmaspheric hiss wave-particle interactions and shows that the waves can be a significant influence on the evolution of the outer radiation belt trapped flux that resides inside the plasmapause.

  19. The FOCON model to assess doses due to the atmospheric radioactive discharges of nuclear facilities during normal operation

    International Nuclear Information System (INIS)

    The FOCON model to assess doses due to the atmospheric radioactive discharges of nuclear facilities during normal operation. To assess the dosimetric impact to the public due to atmospheric radioactive discharges of nuclear facilities during normal operation, the Institute for Protection and Nuclear Safety has developed the FOCON96 code. FOCON96 calculates the dispersion of gases and aerosols into the environment (atmosphere contamination and ground deposition), their transfer in the biosphere (soils, plants and animals) and their impact to a member of the public (individual effective and equivalent doses, external exposure to the plume and to the deposits, internal exposure by inhalation and ingestion). FOCON96 uses ergonomic windows and proposes many capabilities (modular architecture, default values, choice of libraries, access to all the parameters of the models, listing or results, management of result files, calculations made directly, etc.). In the European context, and intercomparison with the PC-CREAM code, developed by the National Radiological Protection Board, has shown the coherence of the results of the two codes. A comparison of the windows and capabilities has shown that FOCON96 was easier to use. FOCON96 is not adapted to calculate the doses received during one particular year that are due to the discharges of a facility in operation for a long period of time. An evolution of the software will be considered if this kind of assessment is generalized. (authors)

  20. Copper Corrosion by Atmospheric Pollutants in the Electronics Industry

    OpenAIRE

    Benjamin Valdez Salas; Michael Schorr Wiener; Roumen Zlatev Koytchev; Gustavo López Badilla; Rogelio Ramos Irigoyen; Monica Carrillo Beltrán; Nicola Radnev Nedev; Mario Curiel Alvarez; Navor Rosas Gonzalez; Jose María Bastidas Rull

    2013-01-01

    Hydrogen sulphide (H2S) is considered one of the most corrosive atmospheric pollutants. It is a weak, diprotic, reducing acid, readily soluble in water and dispersed into the air by winds when emitted from natural, industrial, and anthropogenic sources. It is a pollutant with a high level of toxicity impairing human health and the environment quality. It attacks copper forming thin films of metallic sulphides or dendrite whiskers, which are cathodic to the metal substrate, enhancing corrosion...

  1. 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.

  2. Studies on the effects of atmospheric contamination due to fossil-fuel combustion in Japan

    International Nuclear Information System (INIS)

    Epidemiological studies have been conducted since 1961 to investigate health effects of sulphur dioxide in industrial areas of Japan where fossil-fuel power stations are located. The dose-response relationship between prevalence rates of chronic bronchitis and sulphur dioxide was established. The annual value of sulphur dioxide concentrations estimated by the national network of air pollutant measurements decreased from the peak value of 0.059 ppm in 1967 to 0.017 ppm in 1978. However, the atmospheric concentration of nitrogen dioxide estimated by the national network indicated an annual value of 0.022 ppm in 1968, but the annual value in 1978 was slightly increased to 0.027 ppm. It was therefore considered important to study the health effects of nitrogen dioxide. In six different areas in Japan with varying atmospheric concentrations of nitrogen dioxide, an extensive epidemiological survey was conducted with 12,717 school-children 6 to 12 years old during the period 1979 to 1981. The prevalence rate of asthma was estimated to be 4.7% for males and 2.1% for females in the high NO2 concentration area, and 1.9% for males and 0.9% for females in the low NO2 concentration area. For asthmalike symptoms, 12.2% for males and 11.9% for females was observed at the high NO2 concentration area, and 7.1% for males and 5.9% for females in the low NO2 concentration area. The natural radioactivity from fossil-fuel power plants as well as risk/benefit comparisons are also discussed. In decision-making on environmental protection and safety, it should be carefully considered whether a reduction of one type of risk might increase another type of risk. Not only the risk-reduction industries but also the construction and operation of the risk-reduction system may not be completely riskless

  3. Recent Northern Hemisphere stratospheric HCl increase due to atmospheric circulation changes.

    Science.gov (United States)

    Mahieu, E; Chipperfield, M P; Notholt, J; Reddmann, T; Anderson, J; Bernath, P F; Blumenstock, T; Coffey, M T; Dhomse, S S; Feng, W; Franco, B; Froidevaux, L; Griffith, D W T; Hannigan, J W; Hase, F; Hossaini, R; Jones, N B; Morino, I; Murata, I; Nakajima, H; Palm, M; Paton-Walsh, C; Russell, J M; Schneider, M; Servais, C; Smale, D; Walker, K A

    2014-11-01

    The abundance of chlorine in the Earth's atmosphere increased considerably during the 1970s to 1990s, following large emissions of anthropogenic long-lived chlorine-containing source gases, notably the chlorofluorocarbons. The chemical inertness of chlorofluorocarbons allows their transport and mixing throughout the troposphere on a global scale, before they reach the stratosphere where they release chlorine atoms that cause ozone depletion. The large ozone loss over Antarctica was the key observation that stimulated the definition and signing in 1987 of the Montreal Protocol, an international treaty establishing a schedule to reduce the production of the major chlorine- and bromine-containing halocarbons. Owing to its implementation, the near-surface total chlorine concentration showed a maximum in 1993, followed by a decrease of half a per cent to one per cent per year, in line with expectations. Remote-sensing data have revealed a peak in stratospheric chlorine after 1996, then a decrease of close to one per cent per year, in agreement with the surface observations of the chlorine source gases and model calculations. Here we present ground-based and satellite data that show a recent and significant increase, at the 2σ level, in hydrogen chloride (HCl), the main stratospheric chlorine reservoir, starting around 2007 in the lower stratosphere of the Northern Hemisphere, in contrast with the ongoing monotonic decrease of near-surface source gases. Using model simulations, we attribute this trend anomaly to a slowdown in the Northern Hemisphere atmospheric circulation, occurring over several consecutive years, transporting more aged air to the lower stratosphere, and characterized by a larger relative conversion of source gases to HCl. This short-term dynamical variability will also affect other stratospheric tracers and needs to be accounted for when studying the evolution of the stratospheric ozone layer. PMID:25373680

  4. Variable radio-frequency cold atmospheric He + O2 discharges: from electron-heating mechanism to reactive species delivery

    International Nuclear Information System (INIS)

    Evolution of electron-heating processes with driving frequency and their effects on production reactive oxygen species (ROS) are studied for low-temperature radio-frequency atmospheric helium–oxygen plasma. With increasing frequency from 13.54 to 108.48 MHz at a constant power density of 40 W cm−3, the space-averaged electron density is found to increase by 35% but this is accompanied by marked decrease in the sheath thickness, the maximum electron temperature, and the electric field in the sheath by 76%, 46% and four-folds, respectively. As a result, plasma species generated via reactions with low threshold electron energy (e.g. O2*) experience more abundant production and those generated by energetic electrons (e.g. O and O*) undergo a reduction in their number densities as the driving frequency increases. These frequency dependences directly regulate power dissipation in species produced directly by electrons, ROS concentrations, and ultimately plasma chemistry. Delivery of ROS is shown to be effective only from a boundary layer immediately above a sample surface, due to severely compromised diffusion and drift at atmospheric pressure, introducing a further frequency-dependent factor. In general, the increase of the driving frequency affects energetic and low-energy electrons differently and the contrast in frequency effects of different ROS is desirable for manipulating plasma chemistry as experienced by the sample. (paper)

  5. Atmospheric particulate matter and hospital admission due to lower respiratory tract infection: a case-cross study in Shijiazhuang, China

    Directory of Open Access Journals (Sweden)

    Zi-na BAI

    2016-03-01

    Full Text Available Objective  To explore the association between atmospheric particulate matter (PM10/PM2.5 levels and hospital admissions due to lower respiratory tract infection in Shijiazhuang. Methods  Data of air pollution, meteorologic data, and the data of patients admitted to hospital due to lower respiratory tract infection were retrospectively analyzed. Pearson's correlation coefficients were calculated to analyze correlations between atmospheric particulate matter and meteorologic factors. Data of hospital admission due to lower respiratory tract infection and of atmospheric air pollution levels in Shijiazhuang were obtained, a bidirectional case-crossover design was used to investigate the association between hospital admissions due to lower respiratory tract infection and levels of atmospheric particles. Stratified analyses of exposure based on age, gender, complications and season were performed to evaluate the effect. Results  Pearson's correlation analysis showed positive correlations among PM2.5, PM10, SO2, NO2 and CO. The concentration of all these five pollutants were negatively correlated with O3 and daily mean temperature, while a positive correlation was found between concentrations of the 5 pollutants and daily average temperature and O3. In single-pollutant model, every 10μg/m3 increase in PM2.5 and PM10 at lag5 brought the corresponding OR values (95%CI up to 1.010(1.005-1.015 and 1.006(1.003-1.009 respectively. In the multi-pollutant models, the observed effects of PM2.5 remained significant. Stratified analysis based on gender, age, season and comorbidities showed that the effect of PM2.5 exposure on lower respiratory tract infection admissions was stronger in males, persons younger than 60 years of age and persons without comorbidities, and even more stronger in cold season. The effect of PM10 exposure on lower respiratory tract infection admissions was stronger in females, persons older than 60 years of age and persons with

  6. Distortion of Crabbed Bunch Due to Electron Cloud and Global Crabbing

    International Nuclear Information System (INIS)

    Crab cavities may be used improve the luminosity in colliding beam colliders with crab crossing. In a global crab crossing correction, only one crab cavity is installed in each ring and the crab cavities generate a horizontally titled bunch oscillating around the ring. The electron cloud in positively charged rings may distort the crabbed bunch and cause the luminosity drop. This paper briefly estimates the distortion of positron bunch due to the electron cloud with global crab and estimates the effect in the KEKB and possible LHC upgrades

  7. Modeling ionospheric electron precipitation due to wave particle scattering in the magnetosphere and the feedback effect on the magnetospheric dynamics

    Science.gov (United States)

    Yu, Y.; Jordanova, V.; Ridley, A. J.; Albert, J.; Horne, R. B.; Jeffery, C. A.

    2015-12-01

    Electron precipitation down to the atmosphere caused by wave-particle scattering in the magnetosphere contribute significantly to the enhancement of auroral ionospheric conductivity. Global MHD models that are incapable of capturing kinetic physics in the inner magnetosphere usually adopt MHD parameters to specify the precipitation flux to estimate auroral conductivity, hence losing self-consistency in the global circulation of the magnetosphere-ionosphere system. In this study we improve the coupling structure in global models by connecting the physics-based (wave-particle scattering) electron precipitation with the ionospheric electrodynamics and investigate the feedback effect on the magnetospheric dynamics. We use BATS-R-US coupled with a kinetic ring current model RAM-SCB that solves pitch angle dependent particle distributions to study the global circulation dynamics during the Jan 25-26, 2013 storm event. Following tail injections, we found enhanced precipitation number and energy fluxes of tens of keV electrons being scattered into loss cone due to interactions with enhanced chorus and hiss waves in the magnetosphere. This results in a more profound auroral conductance and larger electric field imposing on the plasma transport in the magnetosphere. We also compared our results with previous methods in specifying the auroral conductance, such as empirical relation used in Ridley et al. (2004). It is found that our physics-based method develops a larger convection electric field in the near-Earth region and therefore leads to a more intense ring current.

  8. Effects of atmospheric neutrons on advanced micro-electronic devices, standards and applications

    International Nuclear Information System (INIS)

    Since the 1980's, it is known that terrestrial cosmic rays, mainly reported as atmospheric neutrons, can penetrate the natural shielding of buildings, equipments and circuit package and induce soft errors in integrated circuits and breakdown of power devices. The high-energy neutron fluxes of interest, larger than 10 MeV, range between 10 particles/cm2/hour at sea level and 104 particles/cm2/hour at typical airplanes flight altitude of 30000 feet, with modulation due to solar flares. In the 1990's, the phenomenon has pervaded as a consequence of the road-map of electronic devices especially the down-scaling of transistor dimensions, the increase of signal bandwidth and the increase of the size of DRAM and SRAM memory, stand-alone or embedded on processors and system-on-chips. Failure-in-time and soft error rate became unacceptable. Test standards and design solutions have been proposed to maintain reliability of commercial products and improve those used in special high-reliability equipments such as avionic computers. The paper describes the atmospheric neutron flux, the effects in the main classes of devices and specific cases such as neutron induced single event upset observed in CMOS vs. CMOS/SOI and some mitigation issues. In this paper, a model called CCPM (critical cross-point model) is proposed to provide critical graphs of technology node sensitivity along the scaling trend of CMOS. (authors)

  9. 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.

  10. Analytical yield spectrum approach to electron energy degradation in earth's atmosphere

    International Nuclear Information System (INIS)

    Analytical spatial yield spectrum approach has been applied to calculate the electron flux, volume excitation, and ionization rates for monoenergetic electrons incident on the earth's atmosphere. The results have been compared with the previous model calculations of Mantas and Walker (1976) and Banks et al. (1974)

  11. Evaluating bias due to data linkage error in electronic healthcare records.

    OpenAIRE

    Harron, K.; WADE, A.; Gilbert, R.; Muller-Pebody, B; Goldstein, H.

    2014-01-01

    Background Linkage of electronic healthcare records is becoming increasingly important for research purposes. However, linkage error due to mis-recorded or missing identifiers can lead to biased results. We evaluated the impact of linkage error on estimated infection rates using two different methods for classifying links: highest-weight (HW) classification using probabilistic match weights and prior-informed imputation (PII) using match probabilities. Methods A gold-standard dataset was crea...

  12. Energy enhancement and spectrum narrowing in terahertz electron sources due to negative mass instability

    Science.gov (United States)

    Lurie, Yu.; Bratman, V. L.; Savilov, A. V.

    2016-05-01

    Simulations of coherent spontaneous undulator radiation in a waveguide demonstrate that the use of negative mass instability (NMI) for retaining longitudinal sizes of dense electron bunches, which are formed in laser-driven photoinjectors, allows one to increase power capabilities of a terahertz radiation source by many times. The NMI is realized in an undulator with combined helical and over-resonance uniform longitudinal magnetic fields due to nonisochronous longitudinal oscillations of electrons, whose frequencies increase/decrease with increasing/decreasing particle energy. In such conditions, an effective longitudinal size of the bunches can be preserved at long distance even at an extremely high electron density. Correspondingly, an energy extraction efficiency of more than 20% is revealed at a narrow frequency radiation spectrum, suggesting realization of a compact and powerful THz source.

  13. Hysteresis and mode transitions in plasma sheath collapse due to secondary electron emission

    Science.gov (United States)

    Langendorf, Samuel; Walker, Mitchell

    2016-03-01

    In this experiment, hysteresis is observed in the floating potential of wall material samples immersed in a low-temperature plasma as the energy of a prevalent non-thermal electron population is varied from 30-180 eV. It is indicated that the hysteresis is due to secondary electron emission from the wall material surface. Measurements are performed in a filament discharge in argon gas pressure 10 - 4 Torr of order 10 7 cm - 3 plasma number density. The primary ionizing electrons from the discharge filament make up 1%-10% of the overall plasma number density, depending on discharge voltage. Immersed LaB6-coated steel and roughened boron nitride (BN) wall material samples are mounted on the face of a radiative heater, and the wall temperature is controlled from 50-400 °C such that thermionic emission from the LaB6-coated sample is not significant. The energy of the primary plasma electrons from the discharge filament is varied and the floating potentials of the material samples are monitored. The floating potentials are observed to transition to a "collapsed" state as the primary electron energy is increased above 110 and 130 eV for the LaB6 and rough BN, respectively. As primary electron energy is subsequently decreased, the floating potentials do not "un-collapse" until lower energies of 80 and 100 eV, respectively. The hysteresis behavior agrees with a kinetic model. The results may help explain observations of global hysteresis and mode transitions in bounded plasma devices with dielectric walls, significant secondary electron emission, and departures of electron energy distribution function from a thermal Maxwellian.

  14. 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.

  15. [Determination of electron density in atmospheric pressure radio frequency dielectric barrier discharges by Stark broadening].

    Science.gov (United States)

    Li, Sen; Liu, Zhong-wei; Chen, Qiang; Liu, Fu-ping; Wang, Zheng-duo; Yang, Li-zhen

    2012-01-01

    The use of high frequency power to generate plasma at atmospheric pressure is a relatively new development. An apparatus of atmospheric pressure radio frequency dielectric barrier discharge was constructed. Plasma emission based measurement of electron density in discharge columns from Stark broadening Ar is discribed. The spacial profile of electron density was studied. In the middle of the discharge column, as the input power increases from 138 to 248 W, the electron density rises from 4.038 x 10(21) m(-3) to 4.75 x 10(21) m(-3). PMID:22497121

  16. Soft X-ray bremsstrahlung and fluorescent line production in the atmosphere by low energy electrons

    Science.gov (United States)

    Kraushaar, W. L.

    1974-01-01

    The effect of low energy quasi-trapped or precipitating electrons which impact on the counter windows of soft X-ray detectors are discussed. The errors caused by X-rays produced in the residual atmosphere above a rocket-borne detector because of the resemblance to X-rays of cosmic origin are examined. The design and development of counter windows which make it possible to identify the atmospherically produced X-rays are described. Curves are presented to show the following: (1) preliminary low energy electron data from Atmospheric Explorer C, (2) X-ray flux in electron-excited nitrogen and oxygen, (3) typical proportional counter response to low energy cosmic rays, and (4) proportional counter response to X-radiation produced by electrons incident upon a gas of oxygen to nitrogen number of 0.4.

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

    International Nuclear Information System (INIS)

    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 > eUm, where Um is the maximum gap voltage, is relatively small.

  18. 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.

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

    Directory of Open Access Journals (Sweden)

    Campbell Laurence

    2008-02-01

    Full Text Available Abstract 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

  20. Atmospheric pollution due to carbon monoxide from vehicular exhaust in Peshawar

    International Nuclear Information System (INIS)

    Carbon monoxide is a major air pollutant and its main source being vehicular exhaust. Peshawar, like other major cities in Pakistan is facing a serious problem of air pollution due to rapidly increasing traffic. Carbon monoxide level during 600 hours to 1800 hours was studied at sixteen different location were found to have an average carbon monoxide concentration above the threshold limits of nine ppm for eight hours exposure whereas, at one location average carbon monoxide concentration reached the mulimit of 35 ppm for one hour average exposure. Results suggest that at these twelve location, the calculated carboxy haemoglobin level that could be present in the blood of people exposed for eight hours are in the range 2.04-4.85% which can adversely affect the central nervous system and can bring changes in psycho motor functions. (author)

  1. Assessment of the effects of atmospheric neutrons on onboard electronic equipment and search for hardening solutions

    International Nuclear Information System (INIS)

    This work deals with the impact of atmospheric neutrons on complex electronic components such as built-in memories or processors. The first part describes the radiation environment, the neutron-matter interaction and the consequences on electronic devices, and presents the commonly used experimental simulations and the testing methods. The potential of laser beam for testing is highlighted. The second chapter presents the development of a testing platform for various types of memories (MRAM and SDRAM). The equipment and the dedicated software are described. A testing platform for processor is also presented. The third chapter is dedicated to the presentation of a 4 Mbit bulk-type SRAM memory and of its testing involving a laser beam equipment. Several results show the presence of error clusters that may endangered the memory as a whole. These error clusters are due to the architecture of the internal addressing scheme of the memory. The simulation of these error clusters must be improved in order to define an optimized strategy of hardening

  2. 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

  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. Emittance growth due to crab crossing imperfections in electron-ion colliders

    International Nuclear Information System (INIS)

    To achieve luminosities ranging from 1033 to 1035cm-2s-1, future electron-ion colliders require very small beam sizes, together with a large number of bunches. The strong focusing necessary to achieve β-functions as low as 20cm can only be achieved by placing low-β quadrupoles as close as possible to the interaction point (IP). With the beam energies of the ion and electron beam differing by more than an order of magnitude, beams need to be separated before encountering the first ion low-β quadrupole, which would otherwise greatly defocus the lower-energy electron beam. This beam separation can be achieved by either deflecting the electron beam away from the ion beam by means of magnetic dipole fields, or by introduction of a crossing angle large enough as to provide sufficient separation at the first ion beam quadrupole. While the former scheme results in large amounts of synchrotron radiation generated near or even inside the detector volume, the latter significantly reduces the luminosity due to the relatively large ion bunch length. This luminosity reduction can be overcome by application of a crab crossing scheme, thus re-instating head-on collisions. However, due to the high ion beam energy, crab cavity RF voltages in the range of tens of megavolts are required, scaling linearly with the RF wavelength. It is therefore desirable to choose the crab cavity RF frequency as high as possible, thus reducing the required voltage. This paper examines the effect of the finite crab cavity RF wavelength on beam dynamics in the proposed electron-ion colliders eRHIC , ELIC , and LHeC

  5. Tritium surface loading due to contamination of rainwater from atmospheric release at NAPS (2011)

    International Nuclear Information System (INIS)

    Annual tritium (HTO) surface loading has been measured and calculated for the year 2011 within 0.8 km distance from 145 m high stack of Narora Atomic Power Station (NAPS) at eight locations in different directions. The technique for measured values consists of the summation of product of tritium concentration (Bq/l) in daily rainfall samples and daily rainfall (mm). Tritium surface loading studies at NAPS reveal that a fraction 1.01E-03 of total annual tritium released through stack gets deposited on the surface due to washout/rainout of plume within 0.8 km radial distance from stack. The range of deposition velocity, Vw (m.s-1) i.e., the ratio of annual tritium surface loading W (Bq. m-2.s-1) and annual mean tritium concentration in air, c0(Bq.m-3) at three locations for the years 2011 is found to be 6.12E-04 to 2.89E-03. The average value for wet deposition velocity Vw for NAPS site is estimated as 3.17E-03 m.s-1. (author)

  6. Tritium surface loading due to contamination of rainwater from atmospheric release at NAPS

    International Nuclear Information System (INIS)

    Annual tritium (HTO) surface loading has been measured and calculated for the year 1998-99 within 0.8 km distance from 145m high stack of Narora Atomic Power Station (NAPS) at eight locations in different directions. The technique for measured values consists of the summation of product of tritium concentration (Bq/l) in daily rainfall samples and daily rainfall (mm) whereas that for calculated values having the use of prevailing meteorological conditions and average tritium release rate during a year. The ratios of measured and calculated values of tritium surface loading during the years 1998-99 are found to be in the range of 0.18 to 6.97. Tritium surface loading studies at NAPS reveal that a fraction 1.7E-03 of total annual tritium released through stack gets deposited on the surface due to washout / rainout of plume within 0.8 km radial distance from stack. The range of deposition velocity, V w (m.s-1) i.e the ratio of annual tritium surface loading W(Bq.m-2.s-1) and annual mean tritium concentration in air, χo(Bq.m-3) at three locations for the years 1998-99 is found to be 5.59E-04 to 5.99E-03 ms-1. The average value for wet deposition velocity V barw for NAPS site is estimated as 2.92E-03 m.s-1. (author)

  7. Risk assessment of atmospheric contamination due to combustion of fossil-fuels in Japan and possible application of fuzzy set

    International Nuclear Information System (INIS)

    For risk assessment of atmospheric contamination due to fossil-fuel combustion in Japan, epidemiological studies have been conducted since 1961. Health effects of sulfur dioxide in industrial areas of Japan where fossil-fuel power stations are located have been investigated. The dose-response relationship between prevalence rates of chronic bronchitis and sulphur dioxide was established. Various efforts have been made to reduce the concentrations of sulfur dioxide in the atmosphere. However, the average concentration of NO2 tended to increase gradually. It was therefore considered important to study the health effects of nitrogen dioxide. In different areas of Japan with varying atmospheric concentrations of nitrogen dioxide, an extensive epidemiological survey was conducted with over 10,000 school-children. The results of the survey indicate that the prevalence rates of asthma and wheezing were higher with the higher degree of air pollution, and that the indoor pollution is important. It is also attempted to compare hazard indices of the air-borne wastes from fossil-fuel power plants and those from nuclear power plants. The conventional pollutants seem to be much more important as compared with the radioactive releases under normal conditions of operation. The survey of stochastic effects with very small chances of occurrence was not attempted because of the great uncertainties and difficulties in identifying a small signal within a large noise. The possible application of the theory of Fuzzy Set for risk analysis is suggested

  8. Effective dose and organ doses due to gas Bremsstrahlung from electron storage rings

    International Nuclear Information System (INIS)

    Bremsstrahlung on residual gas is an important source of beam losses in electron-positron storage rings. The Bremsstrahlung photons are emitted in a narrow cone in the forward direction, which produces a 'hot spot' of dose at the end of a straight section. Estimates of radiation hazard due to gas Bremsstrahlung have so far been performed by calculating the maximum dose equivalent (MADE) or similar quantities. However, the use of quantities conceived for broad parallel beams in the case of very narrow beams significantly overestimates the organ doses and effective dose. In this paper a more sophisticated computational model was used to calculate values of effective dose and absorbed doses in various organs due to gas Bremsstrahlung X-rays generated by 0.1-10 GeV electrons. The Bremsstrahlung photons generated by the interaction of a mono-energetic electron beam in a 1 m long air target were made to impinge on a selected organ of an hermaphrodite anthropomorphic mathematical model placed at 1 and 10 m distances from the end of the target. Organ dose and effective dose were calculated for five representative organs, namely the right eye, ovaries, breast, testes and thyroid. Fits to the calculated values are given, as well as the dependence of photon fluence and dosimetric quantities on various parameters. The results are compared with previous estimates based on MADE and with values of ambient dose equivalent. (authors)

  9. 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.

  10. Simulation of a runaway electron avalanche developing in an atmospheric pressure air discharge

    International Nuclear Information System (INIS)

    To gain a better understanding of the operation of atmospheric pressure air discharges, the formation of a runaway electron beam at an individual emission site on the cathode has been numerically simulated. The model provides a description of the dynamics of the fast electrons emitted into an air gap from the surface of the emission zone by solving numerically two-dimensional equations for the electrons. It is supposed that the electric field at the surface of the emission zone is enhanced, providing conditions for continuous acceleration of the emitted electrons. It is shown that the formation of a runaway electron beam in a highly overvolted discharge is largely associated with avalanche-type processes and that the number of electrons in the avalanche reaches 50% of the total number of runaway electrons

  11. Supershort electron beam and voluminous heavy-current air discharge at atmospheric pressure

    International Nuclear Information System (INIS)

    The conditions of the electron beam and voluminous discharge formation in the air at the atmospheric pressure and subnanosecond pulse tension front are studied. It is shown that the electron beam in the gaseous diode originates at the pulse tension front over time of ∼ 0.5 ns and has duration at the semiheight of ≤0.4 ns. The electron beam with the electrons average energy of 60-80 keV and current amplitude of ≥70 A is obtained. It is assumed that the electron beam is formed from the electron avalanches, originating in the gap on the account of the gas ionization by fast electrons at achieving the critical field between the expanding plasma cloud front and anode

  12. Impact of electron chemistry on the structure and composition of Io's atmosphere

    Science.gov (United States)

    Smyth, William H.; Wong, M. C.

    2004-09-01

    Two-dimensional model calculations (altitude and solar zenith angle) are performed to investigate the impact of electron chemistry on the composition and structure of Io's atmosphere. The calculations are based upon the model of Wong and Smyth (2000, Icarus 146, 60-74) for Io's SO 2 sublimation atmosphere with the addition of new electron chemistry, where the interactions of the electrons and neutrals are treated in a simple fashion. The model calculations are presented for Io's atmosphere at western elongation (dusk ansa) for both a low-density case (subsolar temperature of 113 K) and a high-density case (subsolar temperature of 120 K). The impact of electron-neutral chemistry on the composition and structure of Io's atmosphere is confined primarily to an interaction layer. The penetration depth of the interaction layer is limited to high altitudes in the thicker dayside atmosphere but reaches the surface in the thinner dayside and/or nightside atmosphere at larger solar zenith angles. Within most of the thicker dayside atmosphere, the column density of SO 2 is not significantly altered by electrons, but in the interaction layer all number densities are significantly altered: SO 2 is reduced, O, SO, S, and O 2 are greatly enhanced, and O, SO, and S become comparable to SO 2 at high altitudes. For the thinner nightside atmosphere, the species number densities are dramatically altered: SO 2 is drastically reduced to the least abundant species of the SO 2 family, SO and O 2 are significantly reduced at all altitudes, and O and S are dramatically enhanced and become the dominant species at all altitudes except near the surface. The interaction layer also defines the location of the emission layer for neutrals excited by electron impact and hence determines the fraction of the total neutral column density that is visible in remote observation. Electron chemistry may also impact the ratio of the equatorial to polar SO 2 column density deduced from Lyman- α images and

  13. Assessment of radiological impact due to a hypothetical core disruptive accident for PFBR using an advanced atmospheric dispersion system

    International Nuclear Information System (INIS)

    Radiological impact due to air borne effluent dispersion from a hypothetical Core Disruptive Accident (CDA) scenario for Prototype Fast Breeder Reactor (PFBR) at Kalpakkam coastal site is estimated using an advanced system consisting of a 3-d meso-scale atmospheric model and a random walk particle dispersion model. A simulation of dispersion for CDA carried out for a typical summer day on 24th May 2003 predicted development of land-sea breeze circulation and Thermal Internal Boundary Layer (TIBL) at Kalpakkam site, which have been confirmed by observations. Analysis of dose distribution corresponding to predicted atmospheric conditions shows maximum dose from stack releases beyond the site boundary at about 4 km during TIBL fumigation and stable conditions respectively. A multi mode spatial concentration distribution has been noticed with diurnal meandering of wind under land sea breeze circulation. Over a meso-scale range of 25 km, turning of plume under sea breeze and maximum concentration along plume centerline at distances of 3 to 10 km have been noticed. The study has enabled to simulate the more complex meteorological situation that is actually present at the site. (author)

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

    Directory of Open Access Journals (Sweden)

    V. G. Bulgakov

    2015-09-01

    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.

  15. 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...

  16. Atmospheric Corrosion on Steel Studied by Conversion Electron Mössbauer Spectroscopy

    Science.gov (United States)

    Nakanishi, Akio; Kobayashi, Takayuki

    2004-12-01

    In order to investigate initial products on steel by atmospheric corrosion, conversion electron Mössbauer measurements were carried out at temperatures between 15 K and room temperature. From the results obtained at low temperatures, it was found that the corrosion products on steel consisted of ferrihydrite.

  17. 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.

  18. 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.

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

    International Nuclear Information System (INIS)

    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

  20. 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. PMID:18356524

  1. Nonequilibrium atmospheric pressure plasma with ultrahigh electron density and high performance for glass surface cleaning

    International Nuclear Information System (INIS)

    We produced a nonequilibrium atmospheric pressure plasma by applying an alternative current between two electrodes. The gas temperature and electron density were evaluated using optical emission spectroscopy. It was found that the plasma had gas temperatures from 1800 to 2150 K and ultrahigh electron densities in the order of 1016 cm-3. A remarkably high oxygen radical concentration of 1.6x1015 cm-3 was obtained at a 1% O2/Ar gas flow rate of 15 slm (standard liters per minute). Contact angles below 10 deg. were obtained in the process of glass cleaning with a plasma exposure time of 23 ms

  2. Experimental Evidence of Giant Electron - Gamma Bursts Generated by Extensive Atmospheric Showers in Thunderclouds

    CERN Document Server

    Gurevich, A V; Chubenko, A P; Duncan, L M; Ryabov, V A; Shepetov, A S; Antonova, V P; Kryukov, S V; Piscal, V V; Ptitsyn, M O; Vildanova, L I; Shlyugaev, Y V; Zybin, K P; Shlyugaev, Yu.V.

    2004-01-01

    The existence of a new phenomena - giant electron-gamma bursts is established. The bursts are generated in thunderclouds as a result of the combined action of runaway breakdown and extensive atmosphere showers (RB-EAS). The experiments were fulfilled at the Tien Shan Mountain Scientific Station using EAS-Radio installation. This specially constructed installation consists of a wide spread EAS trigger array and a high time resolution radiointerferometer.

  3. Experimental evidence of giant electron-gamma bursts generated by extensive atmospheric showers in thunderclouds

    Energy Technology Data Exchange (ETDEWEB)

    Gurevich, A.V.; Karashtin, A.N.; Chubenko, A.P.; Duncan, L.M.; Ryabov, V.A.; Shepetov, A.S.; Antonova, V.P.; Kryukov, S.V.; Piscal, V.V.; Ptitsyn, M.O.; Vildanova, L.I.; Shlyugaev, Yu.V.; Zybin, K.P

    2004-05-24

    The existence of a new phenomena--giant electron-gamma bursts is established. The bursts are generated in thunderclouds as a result of the combined action of runaway breakdown and extensive atmosphere showers (RB-EAS). The experiments were fulfilled at the Tien Shan Mountain Scientific Station using EAS-radio installation. This specially constructed installation consists of a wide spread EAS trigger array and a high time resolution radiointerferometer.

  4. Development of electron neutrino showers at mid and high altitudes in the atmosphere

    International Nuclear Information System (INIS)

    JEM-EUSO is a mission intended to detect the fluorescence light produced by the secondary charge particles generated by ultra high energy cosmic rays interacting in the Earth atmosphere. In this work we study in detail the characteristics of longitudinal profiles of electron neutrino showers which, in regions of large air density are dominated by the Landau Pomeranchuk Migdal (LPM) effect. We believe that these characteristics have grate importance for its identification when such showers are observed from the space.

  5. The measurement of the electron temperature in a spark discharge in air at atmospheric pressure

    International Nuclear Information System (INIS)

    The electron temperature in atmospheric pressure spark surface discharge was measured from the relative intensity ratio using several well-resolved atomic N I, N II, O II lines. The evaluated value is of 18 000 K. The repeated sparks were glowed by a pulsed high voltage source which restricted the are phase of sparks by appropriate low value of capacitors in voltage multiplier. (Authors)

  6. Anomalous Electron Transport Due to Multiple High Frequency Beam Ion Driven Alfven Eigenmode

    Energy Technology Data Exchange (ETDEWEB)

    Gorelenkov, N. N.; Stutman, D.; Tritz, K.; Boozer, A.; Delgardo-Aparicio, L.; Fredrickson, E.; Kaye, S.; White, R.

    2010-07-13

    We report on the simulations of recently observed correlations of the core electron transport with the sub-thermal ion cyclotron frequency instabilities in low aspect ratio plasmas of the National Spherical Torus Experiment (NSTX). In order to model the electron transport of the guiding center code ORBIT is employed. A spectrum of test functions of multiple core localized Global shear Alfven Eigenmode (GAE) instabilities based on a previously developed theory and experimental observations is used to examine the electron transport properties. The simulations exhibit thermal electron transport induced by electron drift orbit stochasticity in the presence of multiple core localized GAE.

  7. Mount Aragats as a stable electron accelerator for atmospheric high-energy physics research

    Science.gov (United States)

    Chilingarian, Ashot; Hovsepyan, Gagik; Mnatsakanyan, Eduard

    2016-03-01

    Observation of the numerous thunderstorm ground enhancements (TGEs), i.e., enhanced fluxes of electrons, gamma rays, and neutrons detected by particle detectors located on the Earth's surface and related to the strong thunderstorms above it, helped to establish a new scientific topic—high-energy physics in the atmosphere. Relativistic runaway electron avalanches (RREAs) are believed to be a central engine initiating high-energy processes in thunderstorm atmospheres. RREAs observed on Mount Aragats in Armenia during the strongest thunderstorms and simultaneous measurements of TGE electron and gamma-ray energy spectra proved that RREAs are a robust and realistic mechanism for electron acceleration. TGE research facilitates investigations of the long-standing lightning initiation problem. For the last 5 years we were experimenting with the "beams" of "electron accelerators" operating in the thunderclouds above the Aragats research station. Thunderstorms are very frequent above Aragats, peaking in May-June, and almost all of them are accompanied with enhanced particle fluxes. The station is located on a plateau at an altitude 3200 asl near a large lake. Numerous particle detectors and field meters are located in three experimental halls as well as outdoors; the facilities are operated all year round. All relevant information is being gathered, including data on particle fluxes, fields, lightning occurrences, and meteorological conditions. By the example of the huge thunderstorm that took place at Mount Aragats on August 28, 2015, we show that simultaneous detection of all the relevant data allowed us to reveal the temporal pattern of the storm development and to investigate the atmospheric discharges and particle fluxes.

  8. Possibility of superconductivity due to electron-phonon interaction in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Einenkel, Matthias; Efetov, Konstantin [Institut fuer Theoretische Physik III, Ruhr-Universitaet Bochum (Germany)

    2012-07-01

    We discuss the possibility of superconductivity in graphene taking into account both electron-phonon and electron-electron Coulomb interactions. The analysis is carried out assuming that the Fermi energy is far away from the Dirac points, such that the density of the particles (electrons or holes) is high. We derive proper Eliashberg equations that allow us to estimate the critical superconducting temperature. The most favorable is pairing of electrons belonging to different valleys in the spectrum. Using values of electron-phonon coupling estimated in other publications we obtain the critical temperature as a function of the electron (hole) density. This temperature can reach the order of 10 K at the Fermi energy of order 1-2 eV. We show that the dependence of the intervalley pairing on the impurity concentration should be weak.

  9. Possibility of superconductivity due to electron-phonon interaction in graphene

    International Nuclear Information System (INIS)

    We discuss the possibility of superconductivity in graphene taking into account both electron-phonon and electron-electron Coulomb interactions. The analysis is carried out assuming that the Fermi energy is far away from the Dirac points, such that the density of the particles (electrons or holes) is high. We derive proper Eliashberg equations that allow us to estimate the critical superconducting temperature. The most favorable is pairing of electrons belonging to different valleys in the spectrum. Using values of electron-phonon coupling estimated in other publications we obtain the critical temperature as a function of the electron (hole) density. This temperature can reach the order of 10 K at the Fermi energy of order 1-2 eV. We show that the dependence of the intervalley pairing on the impurity concentration should be weak.

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

    International Nuclear Information System (INIS)

    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 Ti/Te = 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

  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. Electronic double refraction due to the Rashba effect: Analytical and numerical results

    Institute of Scientific and Technical Information of China (English)

    SHAO Peng-rui; DENG Wen-ji

    2007-01-01

    By analogy with the classic effect of the double refraction of light, we investigate the relevant effect of an electron entering from the Non-Rashba region to the Rashba region in two-dimensional systems. It is shown that the effect of electronic double refraction is determined by a combined parameter y=m*λF α/2πh2, rather than both the Rashba coefficient α and wavelength λF of a Fermi electron, separately. For the case of normal incidence, the analytical expressions for the wavefunction of the electron are presented; it is predicted that the Rashba spin-orbit coupling can induce a current perpendicular to the normal incident direction of the electron. Moreover, the general case of incident electron with any given momentum and spin state are studied numerically in detail, including the abrupt changes of spin direction and the two-step characters for reflection.

  13. Anomalous Coulomb Drag in Electron-Hole Bilayers due to the Formation of Excitons

    Science.gov (United States)

    Efimkin, Dmitry K.; Galitski, Victor

    2016-01-01

    Several recent experiments have reported an anomalous temperature dependence of the Coulomb drag effect in electron-hole bilayers. Motivated by these puzzling data, we study theoretically a low-density electron-hole bilayer, where electrons and holes avoid quantum degeneracy by forming excitons. We describe the ionization-recombination crossover between the electron-hole plasma and exciton gas and calculate both the intralayer and drag resistivity as a function of temperature. The latter exhibits a minimum followed by a sharp upturn at low temperatures, in qualitative agreement with the experimental observations [see, e.g., J. A. Seamons et al., Phys. Rev. Lett. 102, 026804 (2009)]. Importantly, the drag resistivity in the proposed scenario is found to be rather insensitive to a mismatch in electron and hole concentrations, in sharp contrast to the scenario of electron-hole Cooper pairing.

  14. 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.

  15. Simulating gamma-ray energy resolution in scintillators due to electron-hole pair statistics

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, R.D., E-mail: rdnarayan@gmail.com [Arizona State University, Department of Physics, P.O. Box 871504, Tempe, AZ 85287-1504 (United States); Miranda, R., E-mail: ryan.miranda@asu.edu [Arizona State University, Department of Physics, P.O. Box 871504, Tempe, AZ 85287-1504 (United States); Rez, P., E-mail: peter.rez@asu.edu [Arizona State University, Department of Physics, P.O. Box 871504, Tempe, AZ 85287-1504 (United States)

    2011-11-15

    The best-possible limit to gamma-ray energy resolution in scintillators is given by the statistics of the number of electron-hole pairs produced by an incident gamma-ray, characterized by the Fano factor. The Fano factor is primarily controlled by the inelastic scattering during the electron cascade, which could be modeled by Monte Carlo simulation. Commonly used radiation transport codes do not follow the electrons to low enough energies to calculate electron-hole pair distributions. A Monte Carlo simulation for inelastic electron scattering is introduced based on cross-sections derived from data measured by Electron Energy-Loss Spectroscopy (EELS) for fast electrons. This inelastic scattering model was incorporated into the radiation transport code Penelope so that it could accurately count the number of electron-hole pairs produced by a gamma-ray. The Fano factor was calculated for the scintillators cerium fluoride (CeF{sub 3}) and lutetium oxyorthosilicate (Lu{sub 2}SiO{sub 5}).

  16. Simulating gamma-ray energy resolution in scintillators due to electron-hole pair statistics

    International Nuclear Information System (INIS)

    The best-possible limit to gamma-ray energy resolution in scintillators is given by the statistics of the number of electron-hole pairs produced by an incident gamma-ray, characterized by the Fano factor. The Fano factor is primarily controlled by the inelastic scattering during the electron cascade, which could be modeled by Monte Carlo simulation. Commonly used radiation transport codes do not follow the electrons to low enough energies to calculate electron-hole pair distributions. A Monte Carlo simulation for inelastic electron scattering is introduced based on cross-sections derived from data measured by Electron Energy-Loss Spectroscopy (EELS) for fast electrons. This inelastic scattering model was incorporated into the radiation transport code Penelope so that it could accurately count the number of electron-hole pairs produced by a gamma-ray. The Fano factor was calculated for the scintillators cerium fluoride (CeF3) and lutetium oxyorthosilicate (Lu2SiO5).

  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. A case study of electron precipitation fluxes due to plasmaspheric hiss

    Czech Academy of Sciences Publication Activity Database

    Hardman, R.; Clilverd, M. A.; Rodger, C. J.; Brundell, J. B.; Duthie, R.; Holzworth, R. H.; Mann, I. R.; Milling, D. K.; Macúšová, Eva

    2015-01-01

    Roč. 120, č. 8 (2015), s. 6736-6748. ISSN 2169-9380 Institutional support: RVO:68378289 Keywords : plasmasphere * plasmaspheric hiss * electron precipitation * radiation belt electrons Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.440, year: 2013 http://onlinelibrary.wiley.com/doi/10.1002/2015JA021429/abstract

  19. 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.

  20. Comparative Experimental Investigation of Titan's Atmospheric Chemistry Driven by Solar EUV Radiation and Energetic Electron Precipitation

    Science.gov (United States)

    Imanaka, Hiroshi; Lavvas, P.; Yelle, R. V.; Smith, M. A.

    2010-10-01

    The observations by the Cassini Ion Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS) clearly demonstrate the importance of complex organic chemistry in the upper atmosphere of Titan; a complex coupling of neutral and ion chemistry for organic aerosol generation induced by EUV photons and Saturn's magnetospheric charged particles. To understand the dominant energy source for aerosol formation and its formation chemistry, we comparatively investigate the chemical mechanism in N2/CH4 gas mixtures resulting from EUV-VUV synchrotron radiation (50-150 nm) and tunable mono-energetic electron beam irradiation (5 eV - 2000 eV). These excitation energy sources cover the dominant energy source available in Titan's upper atmosphere. Our previous study of the EUV-VUV photolysis of N2/CH4 gas mixtures revealed the unique role of nitrogen photoionization in the catalytic formation of complex hydrocarbons and in the major nitrogen fixation process in Titan's upper atmosphere (Imanaka and Smith, 2007, 2009, 2010). However, relative roles of ion-molecule reactions and radical/neutral reactions in such complex chemistry remain to be determined. We characterized the electron energy distribution by conducting the Langmuir probe measurements. Degradation of the primary photoelectron from N2 photoionization at 20.6 eV photons is clearly observed, and the electron density rapidly decreases down to 109-10 cm-3, which suggests the complex coupling of ion-molecular reactions and dissociative ion-electron recombination reactions for the observed development of complex organic molecules. The electron beam irradiation experiments at energy larger than 200 eV shows distinct gaseous product distribution with nitrogenated gaseous species from those with EUV irradiation products. The generation of secondary electrons and multiple inelastic collisions of fast electrons might increases the nitrogen fixation efficiency. The much less stringent spin selection rules could

  1. 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.

  2. 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.

  3. Momentum spectra of atmospheric pions, muons, electrons and positrons at balloon altitudes

    International Nuclear Information System (INIS)

    Momentum spectra of pions, muons, electrons and secondary positrons have been measured at an atmospheric depth of 5.8 g cm-2 with the same instrument. Data was collected by the Matter Antimatter Space Spectrometer of the New Mexico State University in a balloon flight in September 1991 at the rigidity cut-off of 4.5 GV c-1 in Fort Sumner, New Mexico. The first measurement of the positive muon spectrum in the range 0.15 GeV c-1 to 2 GeV c-1 is reported in this paper. The spectral index above 3 GeV c-1 of the negative muon momentum spectrum of this measurement is -2.39±0.05 in agreement with analytical cascade calculations which assume a primary proton kinetic energy spectrum with a slope of -2.74±0.02 in the corresponding kinetic energy range. In the momentum interval 300-700 MeV c-1, both negative and positive muon fluxes turn out to be larger than calculated fluxes by a factor of about 1.4. The measurement of the secondary electron and positron energy spectra allows a reliable subtraction of the atmospheric background from the primary electron and positron fluxes which are affected by large uncertainties in most of the experiments. The energy spectra of the secondary particles reported here have the same systematic errors implying a higher relative accuracy with respect to those measurements made in different flights. (author)

  4. Giga-electronvolt electrons due to a transition from laser wakefield acceleration to plasma wakefield acceleration

    International Nuclear Information System (INIS)

    We show through experiments that a transition from laser wakefield acceleration (LWFA) regime to a plasma wakefield acceleration (PWFA) regime can drive electrons up to energies close to the GeV level. Initially, the acceleration mechanism is dominated by the bubble created by the laser in the nonlinear regime of LWFA, leading to an injection of a large number of electrons. After propagation beyond the depletion length, leading to a depletion of the laser pulse, whose transverse ponderomotive force is not able to sustain the bubble anymore, the high energy dense bunch of electrons propagating inside bubble will drive its own wakefield by a PWFA regime. This wakefield will be able to trap and accelerate a population of electrons up to the GeV level during this second stage. Three dimensional particle-in-cell simulations support this analysis and confirm the scenario

  5. Giga-electronvolt electrons due to a transition from laser wakefield acceleration to plasma wakefield acceleration

    Science.gov (United States)

    Masson-Laborde, P. E.; Mo, M. Z.; Ali, A.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.; Rozmus, W.; Teychenné, D.; Fedosejevs, R.

    2014-12-01

    We show through experiments that a transition from laser wakefield acceleration (LWFA) regime to a plasma wakefield acceleration (PWFA) regime can drive electrons up to energies close to the GeV level. Initially, the acceleration mechanism is dominated by the bubble created by the laser in the nonlinear regime of LWFA, leading to an injection of a large number of electrons. After propagation beyond the depletion length, leading to a depletion of the laser pulse, whose transverse ponderomotive force is not able to sustain the bubble anymore, the high energy dense bunch of electrons propagating inside bubble will drive its own wakefield by a PWFA regime. This wakefield will be able to trap and accelerate a population of electrons up to the GeV level during this second stage. Three dimensional particle-in-cell simulations support this analysis and confirm the scenario.

  6. 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.

  7. Monte Carlo simulation for the electron cascade due to gamma rays in semiconductor radiation detectors

    International Nuclear Information System (INIS)

    A Monte Carlo code was developed for simulating the electron cascade in radiation detector materials. The electron differential scattering cross sections were derived from measured electron energy-loss and optical spectra, making the method applicable for a wide range of materials. The detector resolution in a simplified model system shows dependence on the bandgap, the plasmon strength and energy, and the valence band width. In principle, these parameters could be optimized to improve detector performance. The intrinsic energy resolution was calculated for three semiconductors: silicon (Si), gallium arsenide (GaAs), and zinc telluride (ZnTe). Setting the ionization thresholds for electrons and holes is identified as a critical issue, as this strongly affects both the average electron-hole pair energy w and the Fano factor F. Using an ionization threshold from impact ionization calculations as an effective bandgap yields pair energies that are well matched to measured values. Fano factors of 0.091 (Si), 0.100 (GaAs), and 0.075 (ZnTe) were calculated. The Fano factor calculated for silicon using this model was lower than some results from past simulations and experiments. This difference could be attributed to problems in simulating inter-band transitions and the scattering of low-energy electrons.

  8. Monte Carlo simulation for the electron cascade due to gamma rays in semiconductor radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Raman D.; Miranda, Ryan; Rez, Peter [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States)

    2012-03-15

    A Monte Carlo code was developed for simulating the electron cascade in radiation detector materials. The electron differential scattering cross sections were derived from measured electron energy-loss and optical spectra, making the method applicable for a wide range of materials. The detector resolution in a simplified model system shows dependence on the bandgap, the plasmon strength and energy, and the valence band width. In principle, these parameters could be optimized to improve detector performance. The intrinsic energy resolution was calculated for three semiconductors: silicon (Si), gallium arsenide (GaAs), and zinc telluride (ZnTe). Setting the ionization thresholds for electrons and holes is identified as a critical issue, as this strongly affects both the average electron-hole pair energy w and the Fano factor F. Using an ionization threshold from impact ionization calculations as an effective bandgap yields pair energies that are well matched to measured values. Fano factors of 0.091 (Si), 0.100 (GaAs), and 0.075 (ZnTe) were calculated. The Fano factor calculated for silicon using this model was lower than some results from past simulations and experiments. This difference could be attributed to problems in simulating inter-band transitions and the scattering of low-energy electrons.

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

    Science.gov (United States)

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

    2015-11-01

    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.

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

    International Nuclear Information System (INIS)

    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

  12. [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. PMID:24555347

  13. Spatial extent of band bending in diamond due to ion impact as measured by secondary electron emission: Experiment and theory

    International Nuclear Information System (INIS)

    Although hydrogentated diamond emits exceptionally high numbers of electrons upon single ion impact, the secondary electron yield decays at an extremely rapid rate as a function of ion fluence. We report measurements of this rapid decay at extremely low fluences where the ion tracks are widely separated and explain the results by a model based on the downwards bending of the conduction band edge, due to positive charge trapped within the ion track. The present work demonstrates the importance of charge trapping in explaining the electronic properties of diamond and other wide band gap materials

  14. 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 ......, completely balance the beam current, thereby allowing the emission of very high beam currents, Second, the amount of plasma production in the beam-streak is discussed. Results are shown for selected values of the beam energy, spacecraft velocity, and spacecraft altitude....

  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. Direct observation of polyelectrolyte brushes under wet and dry conditions by atmospheric scanning electron microscopy.

    Science.gov (United States)

    Higuchi, Takeshi; Konyuba, Yuji; Nishiyama, Hidetoshi; Suga, Mitsuo; Takahara, Atsushi; Jinnai, Hiroshi

    2016-04-01

    Polyelectrolyte brushes are polyelectrolyte polymers with one end fixed to a substrate. In this study, direct nano-scale visualization of polyelectrolyte brushes was carried out under 'aqueous conditions' by atmospheric scanning electron microscopy. The thickness of the polyelectrolyte brush layer was measured under both dry and aqueous conditions, experimentally confirming the swollen state of the brushes. These experimental findings qualitatively agreed with the results from previous neutron reflectivity experiments using similar polyelectrolyte brushes. Such direct visualization of polymer brushes in real space opens up a new route for better understanding their surface properties, such as friction, adhesion and wettability. PMID:26581481

  17. Electron impact cross-sections and cooling rates for methane. [in thermal balance of electrons in atmospheres and ionospheres of planets and satellites in outer solar system

    Science.gov (United States)

    Gan, L.; Cravens, T. E.

    1992-01-01

    Energy transfer between electrons and methane gas by collisional processes plays an important role in the thermal balance of electrons in the atmospheres and ionospheres of planets and satellites in the outer solar system. The literature is reviewed for electron impact cross-sections for methane in this paper. Energy transfer rates are calculated for elastic and inelastic processes using a Maxwellian electron distribution. Vibrational, rotational, and electronic excitation and ionization are included. Results are presented for a wide range of electron temperatures and neutral temperatures.

  18. Induction of strand breaks in DNA films by low energy electrons and soft X-ray under nitrous oxide atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, Elahe, E-mail: Elahe.Alizadeh@USherbrooke.ca [Groupe en science des radiations, Departement de medecine nucleaire et radiobiologie, Faculte de medecine et des sciences de la sante, Universite de Sherbrooke, Sherbrooke, J1H 5N4 (Canada); Sanche, Leon, E-mail: Leon.Sanche@USherbrooke.ca [Groupe en science des radiations, Departement de medecine nucleaire et radiobiologie, Faculte de medecine et des sciences de la sante, Universite de Sherbrooke, Sherbrooke, J1H 5N4 (Canada)

    2012-01-15

    Five-monolayer (5 ML) plasmid DNA films deposited on glass and tantalum substrates were exposed to Al K{sub {alpha}} X-rays of 1.5 keV under gaseous nitrous oxide (N{sub 2}O) at atmospheric pressure and temperature. Whereas the damage yields for DNA deposited on glass are due to soft X-rays, those arising from DNA on tantalum are due to both the interaction of low energy photoelectrons from the metal and X-rays. Then, the differences in the yields of damage on glass and tantalum substrates, essentially arises from interaction of essentially low-energy electrons (LEEs) with DNA molecules and the surrounding atmosphere. The G-values (i.e., the number of moles of product per Joule of energy absorbed) for DNA strand breaks induced by LEEs (G{sub LEE}) and the lower limit of G-values for soft X-ray photons (G{sub XL}) were calculated and the results compared to those from previous studies under atmospheric conditions and other ambient gases, such as N{sub 2} and O{sub 2}. Under N{sub 2}O, the G-values for loss of supercoiled DNA are 103{+-}15 nmol/J for X-rays, and 737{+-}110 nmol/J for LEEs. Compared to corresponding values in an O{sub 2} atmosphere, the effectiveness of X-rays to damage DNA in N{sub 2}O is less, but the G value for LEEs in N{sub 2}O is more than twice the corresponding value for an oxygenated environment. This result indicates a higher effectiveness for LEEs relative to N{sub 2} and O{sub 2} environments in causing SSB and DSB in an N{sub 2}O environment. Thus, the previously observed radiosensitization of cells by N{sub 2}O may not be only due to OH{sup {center_dot}} radicals but also to the reaction of LEE with N{sub 2}O molecules near DNA. The previous experiments with N{sub 2} and O{sub 2} and the present one demonstrate the possibility to investigate damage induced by LEEs to biomolecules under various types of surrounding atmospheres. - Highlights: > A completely different and new approach is applied to investigate the radiation chemistry of N

  19. Response in Electrostatic Analyzers due to Backscattered Electrons: Case Study Analysis with the Juno JADE-E Instrument

    Science.gov (United States)

    Clark, G. B.; Allegrini, F.; McComas, D. J.; Randol, B. M.; Valek, P. W.

    2012-12-01

    NASA's Juno mission includes the Jovian Auroral Distribution Experiment (JADE) that will measure in situ electrons and ions in Jupiter's polar magnetosphere. JADE consists of three nearly identical electron sensors (JADE-E) and one ion sensor (JADE-I). JADE-E measures full electron pitch angle distributions from 0.1 to 100 keV. The electro-optics are based on an electrostatic analyzer (ESA) with an Ebonol-C blackening surface treatment, and a detection system composed of a MCP stack and 16 individual anodes each with a 7.5 degree field of view. A non-ideal response was observed during calibration with count rates measured on anodes adjacent to the focal anode. The integrated non-ideal response contributes up to ~25%, relative to the ideal signal, for electron beam energies ~30 keV. We propose that this response is due to backscattered electrons (BSEs) from the electron beam off of the ESA coating. With a SIMION model, we explored the angular and energy distributions of BSEs and how they affect the response of JADE-E. Non-ideal responses occur at some level in electron plasma ESAs generally, likely due to the effect of BSEs discussed here.

  20. Studies of suprathermal emission due to cyclotron-electronic heating of the tokamak TCV plasma

    International Nuclear Information System (INIS)

    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 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-up. Transient

  1. Uncertainties in the measurement of the atmospheric velocity due to balloon-gondola pendulum-like motions

    Science.gov (United States)

    Alexander, P.; de la Torre, A.

    2011-02-01

    Balloons lead to the highest vertical resolution of air velocity data actually attainable from atmospheric soundings. However, the pendulum-like motion of the balloon-gondola system may significantly affect these measurements if the distance between balloon and gondola is large. This may prevent the study of the highest vertical resolution range obtained. Also, if not appropriately discriminated, these fluctuations could be confused with small scale or turbulent oscillations of the atmosphere. It is shown from simple energy considerations that horizontal and vertical wind velocity perturbations introduced in the observations by the pendulum motion may usually be comparable to typical measurements. Vertical velocity data that were obtained with an instrumented gondola in a zero pressure balloon, which typically reach the lower stratosphere, are analyzed and found to be in agreement with the above statements. The pendulum-like behavior in this sounding seems to be stimulated by the buoyant oscillation of the atmosphere.

  2. The leaching of vanadium(V) in soil due to the presence of atmospheric carbon dioxide and ammonia

    International Nuclear Information System (INIS)

    The natural leaching of vanadium(V) with CO2 from soil-water in the presence of ammonia, a known precursor to atmospheric aerosols, has been tested by bubbling carbon dioxide through soil suspension with varying amount of ammonia. It was found that the leaching of V(V) is enhanced in the presence of ammonia. From the results of the investigation, it could be concluded that atmospheric CO2 in the presence of ammonia (the only atmospheric gas that increases the pH of soil-water) could naturally leach V(V) from soil. Furthermore, it was also shown that the presence of (NH4)2CO3 in soil could enhance the leaching of toxic V(V) species thereby making it bioavailable for both plants and animals.

  3. 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...

  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. Asymptotical theory of runaway electron diffusion due to magnetic turbulence in Tokamak plasmas

    International Nuclear Information System (INIS)

    Asymptotic theory of transport of runaway electrons in a toroidal plasma in the presence of small-scale magnetic turbulence is proposed. It is based on relativistic Hamiltonian guiding center equations for runaway electrons in toroidal plasmas. Using the asymptotical analysis the explicit relation between the spectral (m, n)- components of perturbation Hamiltonian and the corresponding spectrum of the magnetic turbulence is found. This relation depends only on a few parameters of runaway orbits and magnetic surfaces. The radial profiles of runaway diffusion coefficients are found employing two methods, the quasilinear approximation and the direct calculations using a fast running mapping. The dependence of the shielding factor of the runaway electron parameters and the turbulence spectra is discussed (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Simulated Emittance Growth due to Electron Cloud for SPS and LHC

    CERN Document Server

    Benedetto, Elena; Schulte, Daniel; Zimmermann, Frank

    2004-01-01

    The emittance growth caused by an electron cloud is simulated by the HEADTAIL code with conducting boundary conditions. Under some conditions the simulation results may depend on the number of beam-cloud interaction points, the phase advance between them and the number of macroparticles used to represent beam and cloud. Simulations include a transverse feedback system and, optionally, a large chromaticity, as employed in actual SPS operation. Simulation results for the SPS can be compared with observations, and the emittance growth in the LHC is computed as a function of average electron density. An attempt is made to extrapolate to low electron densities. We also compare the initial instability rise times with those obtained for an equivalent broadband resonator.

  7. An Enhanced Nonlinear Critical Gradient for Electron Turbulent Transport due to Reversed Magnetic Shear

    International Nuclear Information System (INIS)

    The first nonlinear gyrokinetic simulations of electron internal transport barriers (e-ITBs) in the National Spherical Torus Experiment show that reversed magnetic shear can suppress thermal transport by increasing the nonlinear critical gradient for electron-temperature-gradient-driven turbulence to three times its linear critical value. An interesting feature of this turbulence is non- linearly driven off-midplane radial streamers. This work reinforces the experimental observation that magnetic shear is likely an effective way of triggering and sustaining e-ITBs in magnetic fusion devices.

  8. Charge stripes due to electron correlations in the two-dimensional spinless Falicov-Kimball model

    OpenAIRE

    Lemanski, R.; Freericks, J. K.; Banach, G.

    2003-01-01

    We calculate the restricted phase diagram for the Falicov-Kimball model on a two-dimensional square lattice. We consider the limit where the conduction electron density is equal to the localized electron density, which is the limit related to the S_z=0 states of the Hubbard model. After considering over 20,000 different candidate phases (with a unit cell of 16 sites or less) and their thermodynamic mixtures, we find only about 100 stable phases in the ground-state phase diagram. We analyze th...

  9. 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.

  10. An Enhanced Nonlinear Critical Gradient for Electron Turbulent Transport due to Reversed Magnetic Shear

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, J. L.; Hammet, G. W.; Mikkelsen, D. R.; Yuh, H. Y.; Candy, J.; Guttenfelder, W.; Kaye, S. M.; LeBlanc, B.

    2011-05-11

    The first nonlinear gyrokinetic simulations of electron internal transport barriers (e-ITBs) in the National Spherical Torus Experiment show that reversed magnetic shear can suppress thermal transport by increasing the nonlinear critical gradient for electron-temperature-gradient-driven turbulence to three times its linear critical value. An interesting feature of this turbulence is non- linearly driven off-midplane radial streamers. This work reinforces the experimental observation that magnetic shear is likely an effective way of triggering and sustaining e-ITBs in magnetic fusion devices.

  11. 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.

  12. Some aspects of the lattice destruction of polyethylene due to electron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kawaguchi, Akiyoshi; Isoda, Seiji; Ohara, Masayoshi; Katayama, Ken-ichi (Kyoto Univ., Uji (Japan). Inst. for Chemical Research); Haneda, Tsuguo

    1982-03-01

    When n-C/sub 28/H/sub 58/ is exposed to electron beams, the (200) and (110) spacings remain constant independently of irradiation dose, and for the longer paraffins, these spacings increase with the dose. The longer the molecules, the more remarkable their dose dependence is. Polyethylenes are more easily subjected to electron radiation damage than n-C/sub 94/H/sub 190/, although the length of stem segments of both crystals is the same. The difference is caused by that of the crystalline state between them; polyethylene crystals are composed of folded chains, while molecules are extended in n-C/sub 94/H/sub 194/. The fact that the irradiatinon behavior depends on the molecular length is interpreted in terms of molecular mobility within the crystal lattice. Since in the case of paraffins with small length, molecules are very mobile, the lattice strain imposed by electron irradiation is relaxed and apparently the lattice spacings are less dependent on the irradiation dose. Further, the mechanism of lattice destruction of polyethylene is examined using the optical transform method; model lattices are set up and its optical transforms are compared with the electron diffraction patterns. It is found that the cross-link model proposed by Nagasawa and Kobayashi is not suitable as it is.

  13. Some aspects of the lattice destruction of polyethylene due to electron irradiation

    International Nuclear Information System (INIS)

    When n-C28H58 is exposed to electron beams, the (200) and (110) spacings remain constant independently of irradiation dose, and for the longer paraffins, these spacings increase with the dose. The longer the molecules, the more remarkable their dose dependence is. Polyethylenes are more easily subjected to electron radiation damage than n-C94H190, although the length of stem segments of both crystals is the same. The difference is caused by that of the crystalline state between them; polyethylene crystals are composed of folded chains, while molecules are extended in n-C94H194. The fact that the irradiatinon behavior depends on the molecular length is interpreted in terms of molecular mobility within the crystal lattice. Since in the case of paraffins with small length, molecules are very mobile, the lattice strain imposed by electron irradiation is relaxed and apparently the lattice spacings are less dependent on the irradiation dose. Further, the mechanism of lattice destruction of polyethyllen is examined using the optical transform method; model lattices are set up and its optical transforms are compared with the electron diffraction patterns. It is found that the cross-link model proposed by Nagasawa and Kobayashi is not suitable as it is. (author)

  14. 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...

  15. Duration of memory loss due to electron beam exposure. Final report Jan-May 1983

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, T.G.; Tilton, B.M.

    1983-08-01

    Electron beam exposure has been shown to produce retrograde amnesia (RA). The objective of this study was to determine the duration of memory loss upon electron beam exposure. It is important to know if exposure produces a memory loss of the events which occurred in the preceding 1 sec or memory loss of the preceding minute's events. The task was a single-trial avoidance paradigm. The animal was placed in a small aversive chamber. After a 90-sec adaptation period, a door opened that provided access to a large, dark, preferred chamber. The time required for the animal to enter the preferred chamber was the measure of interest (T). Once inside the preferred chamber, a 1-sec footshock was delivered. Following the footshock by some preset delay (delta T), the animal was exposed to a 10-microsec, 10-rad electron beam (or X-ray). A second trial on the task was run 2 hr postexposure. The second trial consisted of placing the animal in the aversive chamber and monitoring the time (T') required to enter the preferred chamber. If the electron beam exposure interfered with the animal's ability to recall the shock, T' would be greatly reduced as compared with the sham controls. The exposure delay times used were delta T = 1, 3, 5, and 10 sec.

  16. 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.

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

    International Nuclear Information System (INIS)

    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 = –z0).

  18. 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}).

  19. Changes in muscle proteins due to treating beef and pork with electron rays

    International Nuclear Information System (INIS)

    In the introduction the authors look at the possible ways of determing, during food inspection, whether meat or meat products have been treated with high-energy-radiation and conclude that there are no reliable methods avalilable at present. Treating vacuum-packed beef and pork with electron rays (β-rays) at doses of 0.2, 1.0 and 5.0 Mrad resulted in a dose-dependent increase in the pH-value of the meat and a decline in the solubility of the sarcoplasmic proteins. The pH-increase was not significant until a dose of 5 Mrad. The same applies to the decline in solubility of sarcoplasmic protein in beef. In pork a significant effect could be observed already at 1.0 Mrad. The sarcoplasmic protein of pig muscle would thus appear to be more sensitive to electron rays than that of bovine muscle. (orig.) 891 AJ/orig. 892 HIS

  20. Self-similar magnetic field penetration of a homogeneous collisionless plasma due to electron velocity advection

    International Nuclear Information System (INIS)

    The velocity advection, me(ve·∇)ve, terms in the momentum equation for electrons in a collisionless plasma are shown to introduce an effective resistivity on the currents drawn from a bounding cathode. This leads to nonlinear diffusive penetration of an externally driven magnetic field, which at time t and height y above the cathode, penetrates to a depth δ obeying the scaling δ∼(t/y)1/3

  1. Intrapelvic dissemination of early low-grade endometrioid stromal sarcoma due to electronic morcellation

    OpenAIRE

    Choo, Kyoung-Ja; Lee, Hyun Joo; Lee, Tae Sung; Kim, Ju Hyun; Koh, Suk Bong; Choi, Youn Seok

    2015-01-01

    Endometrioid stromal sarcoma is a rare malignancy that originates from mesenchymal cells. It is classified into low-grade endometrioid stromal sarcoma (LGESS) and high-grade endometrioid stromal sarcoma. Ultrasonographic findings of LGESS resemble those of submucosal myomas, leading to the possible preoperative misdiagnosis of LGESS as uterine leiomyoma. Electronic morcellation during laparoscopic surgery in women with LGESS can result in iatrogenic intraabdominal dissemination and a poorer p...

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

    International Nuclear Information System (INIS)

    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.)

  3. Enhanced O2+ loss at Mars due to an ambipolar electric field from electron heating

    Science.gov (United States)

    Ergun, R. E.; Andersson, L. A.; Fowler, C. M.; Woodson, A. K.; Weber, T. D.; Delory, G. T.; Andrews, D. J.; Eriksson, A. I.; McEnulty, T.; Morooka, M. W.; Stewart, A. I. F.; Mahaffy, P. R.; Jakosky, B. M.

    2016-05-01

    Recent results from the MAVEN Langmuir Probe and Waves instrument suggest higher than predicted electron temperatures (Te) in Mars' dayside ionosphere above ~180 km in altitude. Correspondingly, measurements from Neutral Gas and Ion Mass Spectrometer indicate significant abundances of O2+ up to ~500 km in altitude, suggesting that O2+ may be a principal ion loss mechanism of oxygen. In this article, we investigate the effects of the higher Te (which results from electron heating) and ion heating on ion outflow and loss. Numerical solutions show that plasma processes including ion heating and higher Te may greatly increase O2+ loss at Mars. In particular, enhanced Te in Mars' ionosphere just above the exobase creates a substantial ambipolar electric field with a potential (eΦ) of several kBTe, which draws ions out of the region allowing for enhanced escape. With active solar wind, electron, and ion heating, direct O2+ loss could match or exceed loss via dissociative recombination of O2+. These results suggest that direct loss of O2+ may have played a significant role in the loss of oxygen at Mars over time.

  4. 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.

  5. Response to Comment on “Radiative absorption enhancements due to the mixing state of atmospheric black carbon”

    Energy Technology Data Exchange (ETDEWEB)

    Cappa, Christopher D.; Onasch, Timothy B.; Massoli, Paola; Worsnop, Douglas R.; Bates, Timothy S.; Cross, Eben S.; Davidovits, Paul; Hakala, Jani; Hayden, Katherine; Jobson, Bertram Thomas; Kolesar, K. R.; Lack, D. A.; Lerner, Brian M.; Li, Shao-Meng; Mellon, Daniel; Nuaaman, Ibraheem; Olfert, Jason N.; Petaja, Tuukka; Quinn, P. K.; Song, Chen; Subramanian, R.; Williams, Eric; Zaveri, Rahul A.

    2013-01-25

    Jacobson argues that our statement that "many climate models may overestimate warming by BC" has not been demonstrated. Jacobson challenges our results on the basis that we have misinterpreted some model results, omitted optical focusing under high relative humidity conditions and by involatile components, and because our measurements consist of only two locations over short atmospheric time periods. We address each of these arguments, acknowledging important issues and clarifying some misconceptions, and stand by our direct observations, conclusions, and stated implications.

  6. Decrease of the electric field penetration into the ionosphere due to low conductivity at the near ground atmospheric layer

    OpenAIRE

    M. Ampferer; V. V. Denisenko; Hausleitner, W.; Krauss, S.; G. Stangl; Boudjada, M. Y.; H. K. Biernat

    2010-01-01

    It is well known that lithospheric electromagnetic emissions are generated before earthquakes occurrence. In our study, we consider the physical penetration mechanism of the electric field from the Earth's surface, through the atmosphere-ionosphere layers, and until its detection in space by satellites. A simplified approach is investigated using the electric conductivity equation, i.e., ∇ˆσ·∇Φ)=0 in the case of a vertical inclina...

  7. Momentum spectra of atmospheric pions, muons, electrons and positrons at balloon altitudes

    Energy Technology Data Exchange (ETDEWEB)

    Codino, A.; Brunetti, M.T.; Federico, C.; Grimani, C.; Lanfranchi, M.; Menichelli, M.; Miozza, M. [Dipartimento di Fisica dell' Universita and Sezione INFN di Perugia, Perugia (Italy); Stochaj, S.J. [Particle Astrophysics Laboratory, New Mexico State University, Las Cruces, NM (United States); Stephens, S.A. [Tata Institute of Fundamental Research, Bombay (India); Mitchell, J.W.; Ormes, J.F.; Streitmatter, R.E. [NASA/Goddard Space Flight Center, Greenbelt, MD (United States); Hof, M.; Pfeifer, C.; Menn, W.; Simon, M. [Universitaet Siegen, Siegen (Germany); Basini, G.; Ricci, M. [Laboratori Nazionale INFN di Frascati, Frascati (Italy); Brancaccio, F.M.; Papini, P.; Piccardi, S.; Spillantini, P. [Dipartimento di Fisica dell' Universita and Sezione INFN di Firenze, Firenze (Italy); De Pascale, M.P.; Morselli, A.; Picozza, P. [Dipartimento di Fisica dell' Universita Tor Vergata and Sezione INFN di Roma II, Roma (Italy)

    1997-11-01

    Momentum spectra of pions, muons, electrons and secondary positrons have been measured at an atmospheric depth of 5.8 g cm{sup -2} with the same instrument. Data was collected by the Matter Antimatter Space Spectrometer of the New Mexico State University in a balloon flight in September 1991 at the rigidity cut-off of 4.5 GV c{sup -1} in Fort Sumner, New Mexico. The first measurement of the positive muon spectrum in the range 0.15 GeV c{sup -1} to 2 GeV c{sup -1} is reported in this paper. The spectral index above 3 GeV c{sup -1} of the negative muon momentum spectrum of this measurement is -2.39{+-}0.05 in agreement with analytical cascade calculations which assume a primary proton kinetic energy spectrum with a slope of -2.74{+-}0.02 in the corresponding kinetic energy range. In the momentum interval 300-700 MeV c{sup -1}, both negative and positive muon fluxes turn out to be larger than calculated fluxes by a factor of about 1.4. The measurement of the secondary electron and positron energy spectra allows a reliable subtraction of the atmospheric background from the primary electron and positron fluxes which are affected by large uncertainties in most of the experiments. The energy spectra of the secondary particles reported here have the same systematic errors implying a higher relative accuracy with respect to those measurements made in different flights. (author)

  8. Stochastic instability of relativistic runaway electrons due to lower hybrid waves

    International Nuclear Information System (INIS)

    Runaway electrons and lower hybrid waves in tokamak discharges are coupled because of the relativistic decrease of the cyclotron frequency. Two interaction regimes must be considered. For the low energy part of the relativistic runaway spectrum, neighboring low harmonic nonlinear cyclotron resonances may overlap. For the high energy part, the influence of the higher order resonances are more conveniently studied with the help of a map describing nearly perpendicular Landau coupling. In both cases it is shown that the stochasticity threshold can be reached in typical discharges, leading to quasilinear diffusion

  9. Use of POES SEM-2 observations to examine radiation belt dynamics and energetic electron precipitation into the atmosphere

    OpenAIRE

    Rodger, Craig J.; Clilverd, Mark A.; Green, Janet C.; Lam, Mai Mai

    2010-01-01

    The coupling of the Van Allen radiation belts to the Earth's atmosphere through precipitating particles is an area of intense scientific interest. Currently, there are significant uncertainties surrounding the precipitating characteristics of medium energy electrons (> 20 keV), and even more uncertainties for relativistic electrons. In this paper we examine roughly 10 years of measurements of trapped and precipitating electrons available from the Polar Orbiting Environmental Satellites (POES)...

  10. Variable Temperature Setup for Scanning Electron Microscopy in Liquids and Atmospheric Pressure Gaseous Environments

    Science.gov (United States)

    Al-Asadi, Ahmed; Zhang, Jie; Li, Jianbo; Denault, Lauraine; Potyrailo, Radislav; Kolmakov, Andrei

    2014-03-01

    A thermoelectric cooling / heating setup for commercial Quantomix QX WETSEM scanning electron microscopy environmental cells was designed and tested. This addition allows extending ambient pressure in situ studies to be conducted in a wide temperature range both in liquid and gaseous environments. Instead of cooling/heating the entire body of QX-WETCELL, ultrathin polyimide electron transparent membrane window supported by metal mesh on the top of the cell has been used as an agent for heat transfer to/ from the Pelltier element. A butterfly wing of Morph sulkowskyi has been used as a model object in the QX-WETCELL's chamber due to its unique micro/nanostructure and peculiar wettability behavior. The dynamics of the water desorption, condensation and freezing processes were observed complementary using both optical microscopy and Scanning Electron Microscopy in vivo. The observations revel that the initial droplet formation were most likely taking place on the top of the wing ridges due to the waxy component of its surface. In addition, The SEM observation showed that the high intensity electron beam can heat the butterfly wing locally delaying the water condensation and freezing processes.

  11. Electronic transport in the quantum spin Hall state due to the presence of adatoms in graphene

    Science.gov (United States)

    Lima, Leandro; Lewenkopf, Caio

    Heavy adatoms, even at low concentrations, are predicted to turn a graphene sheet into a topological insulator with substantial gap. The adatoms mediate the spin-orbit coupling that is fundamental to the quantum spin Hall effect. The adatoms act as local spin-orbit scatterer inducing hopping processes between distant carbon atoms giving origin to transverse spin currents. Although there are effective models that describe spectral properties of such systems with great detail, quantitative theoretical work for the transport counterpart is still lacking. We developed a multiprobe recursive Green's function technique with spin resolution to analyze the transport properties for large geometries. We use an effective tight-binding Hamiltonian to describe the problem of adatoms randomly placed at the center of the honeycomb hexagons, which is the case for most transition metals. Our choice of current and voltage probes is favorable to experiments since it filters the contribution of only one spin orientation, leading to a quantized spin Hall conductance of e2 / h . We also discuss the electronic propagation in the system by imaging the local density of states and the electronic current densities. The authors acknowledge the Brazilian agencies CNPq, CAPES, FAPERJ and INCT de Nanoestruturas de Carbono for financial support.

  12. 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...

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

    International Nuclear Information System (INIS)

    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

  14. 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.

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

    Science.gov (United States)

    Chen, Y. T.; de La Taille, C.; Suomijärvi, T.; Cao, Z.; Deligny, O.; Dulucq, F.; Ge, M. M.; Lhenry-Yvon, I.; Martin-Chassard, G.; Nguyen Trung, T.; Wanlin, E.; Xiao, G.; Yin, L. Q.; Yun Ky, B.; Zhang, L.; Zhang, H. Y.; Zhang, S. S.; Zhu, Z.

    2015-09-01

    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.

  16. 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.

  17. 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.

  18. Oscillation of electron mobility in parabolic double quantum well structure due to applied electric field

    International Nuclear Information System (INIS)

    We show that oscillation of low temperature electron mobility μ can be obtained by applying an electric field F along the growth direction of the asymmetrically barrier delta doped AlxGa1-xAs parabolic double quantum well structure. The drastic changes in the subband Fermi energies and distributions of subband wave functions as a function of F yield nonmonotonic intra- and intersubband scattering rate matrix elements mediated by intersubband effects. The oscillatory enhancement of μ, which is attributed to the subband mobilities governed by the ionized impurity scattering, magnifies with increase in well width and decrease in height of the parabolic structure potential. The results can be utilized for nanoscale low temperature device applications

  19. Dependence of loss rate of electrons due to elastic gas scattering on the shape of the vacuum chamber in an electron storage ring

    CERN Document Server

    Kumar, Pradeep; Ghodke, A D; Singh, Pitamber

    2014-01-01

    The beam lifetime in an electron storage ring is also limited by the loss rate of the stored electrons due to the elastic coulomb scattering of electrons with the nuclei of residual gas atoms. The contribution to the beam lifetime due to this elastic scattering depends upon the shape factor which is governed by the shape of the vacuum chamber. In this paper, analytical expressions for the shape factor for a rectangular and an elliptical vacuum chamber as a function of longitudinal position along the circumference in a storage ring are derived using an approach in which the position of electrons at the focusing quadrupole is transformed to the location of defocusing quadrupole and vice versa to define the parts of the vacuum chamber, where the loss of electrons takes place at the location of quadrupoles. The expressions available in the literature are for the average shape factors. The expression of shape factor for a rectangular chamber derived in this paper are similar to the expression for average shape fac...

  20. 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.

  1. A temporal increase in the atmospheric 210Pb concentration possibly due to the 1991 eruption of Pinatubo volcano. An observation at Seoul, the Republic of Korea

    International Nuclear Information System (INIS)

    A temporal increase in the atmospheric concentration of 210Pb was observed in December, 1991, and January, 1992, at Seoul, the Republic of Korea. This increase was estimated to be due to the fallout of the stratospheric 210Pb originating from the 1991 eruption of Pinatubo volcano, Philippines, along with the aerosol particles injected into the stratosphere by the eruption. The present observation was similar to the previous observations made at Tsukuba Science City, Japan. (author)

  2. Electric fields, electron precipitation, and VLF radiation during a simultaneous magnetospheric substorm and atmospheric thunderstorm

    International Nuclear Information System (INIS)

    A balloon payload instrumented with a double-probe electric field detector and an X ray scintillation counter was launched from Roberval, Quebec, Canada (L=4.1) at 0828 UT (0328 LT) on July 9, 1975. A magnetospheric substorm was observed locally between 0815 and 1100 UT, which produced a maximum ΔB of approx.500 nT at approx.0930 UT. A single-cell atmospheric thunderstorm developed northeast of Roberval beginning around 0925 UT which was most intense from approx.1000 to 1035 UT. Detailed study of the electrical properties of the thunderstorm, the X ray precipitation data, and VLF spheric data leads to three conclusions. First, the electrical coupling from the thunderstorm to the magnetosphere increases with frequency from dc to the VLF; for the observed storm the amplitude at the ionosphere of thunderstorm produced electric fields was not significant at frequencies below 0.1 Hz. Second, the atmospheric conductivity above the thunderstorm was observed to be about one-half the fair weather value prior to 1000 UT; decreased to about one-quarter the fair weather value at about 1000 UT; and remained depressed after the end of the thunderstorm. This result was contrary to that expected on the basis of previous work and is one which merits considerably more investigation. Third, the data show a high probability that half-hop whistlers initiated by sferics from the thunderstorm triggered energetic electron precipitation from the magnetosphere

  3. Rapid imaging of mycoplasma in solution using Atmospheric Scanning Electron Microscopy (ASEM)

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Chikara, E-mail: ti-sato@aist.go.jp [Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566 (Japan); Manaka, Sachie [Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566 (Japan); Nakane, Daisuke [Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585 (Japan); Nishiyama, Hidetoshi; Suga, Mitsuo [Advanced Technology Division, JEOL Ltd., Akishima, Tokyo 196-8558 (Japan); Nishizaka, Takayuki [Department of Physics, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588 (Japan); Miyata, Makoto [Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585 (Japan); Maruyama, Yuusuke [Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566 (Japan)

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer Mycoplasma mobile was observed in buffer with the Atmospheric Scanning Electron Microscope. Black-Right-Pointing-Pointer Characteristic protein localizations were visualized using immuno-labeling. Black-Right-Pointing-Pointer M. mobile attached to sialic acid on the SiN film surface within minutes. Black-Right-Pointing-Pointer Cells were observed at low concentrations. Black-Right-Pointing-Pointer ASEM should promote study and early-stage diagnosis of mycoplasma. -- Abstract: Mycoplasma is a genus of bacterial pathogen that causes disease in vertebrates. In humans, the species Mycoplasma pneumoniae causes 15% or more of community-acquired pneumonia. Because this bacterium is tiny, corresponding in size to a large virus, diagnosis using optical microscopy is not easy. In current methods, chest X-rays are usually the first action, followed by serology, PCR amplification, and/or culture, but all of these are particularly difficult at an early stage of the disease. Using Mycoplasma mobile as a model species, we directly observed mycoplasma in buffer with the newly developed Atmospheric Scanning Electron Microscope (ASEM). This microscope features an open sample dish with a pressure-resistant thin film window in its base, through which the SEM beam scans samples in solution, from below. Because of its 2-3 {mu}m-deep scanning capability, it can observe the whole internal structure of mycoplasma cells stained with metal solutions. Characteristic protein localizations were visualized using immuno-labeling. Cells were observed at low concentrations, because suspended cells concentrate in the observable zone by attaching to sialic acid on the silicon nitride (SiN) film surface within minutes. These results suggest the applicability of the ASEM for the study of mycoplasmas as well as for early-stage mycoplasma infection diagnosis.

  4. Rapid imaging of mycoplasma in solution using Atmospheric Scanning Electron Microscopy (ASEM)

    International Nuclear Information System (INIS)

    Highlights: ► Mycoplasma mobile was observed in buffer with the Atmospheric Scanning Electron Microscope. ► Characteristic protein localizations were visualized using immuno-labeling. ► M. mobile attached to sialic acid on the SiN film surface within minutes. ► Cells were observed at low concentrations. ► ASEM should promote study and early-stage diagnosis of mycoplasma. -- Abstract: Mycoplasma is a genus of bacterial pathogen that causes disease in vertebrates. In humans, the species Mycoplasma pneumoniae causes 15% or more of community-acquired pneumonia. Because this bacterium is tiny, corresponding in size to a large virus, diagnosis using optical microscopy is not easy. In current methods, chest X-rays are usually the first action, followed by serology, PCR amplification, and/or culture, but all of these are particularly difficult at an early stage of the disease. Using Mycoplasma mobile as a model species, we directly observed mycoplasma in buffer with the newly developed Atmospheric Scanning Electron Microscope (ASEM). This microscope features an open sample dish with a pressure-resistant thin film window in its base, through which the SEM beam scans samples in solution, from below. Because of its 2–3 μm-deep scanning capability, it can observe the whole internal structure of mycoplasma cells stained with metal solutions. Characteristic protein localizations were visualized using immuno-labeling. Cells were observed at low concentrations, because suspended cells concentrate in the observable zone by attaching to sialic acid on the silicon nitride (SiN) film surface within minutes. These results suggest the applicability of the ASEM for the study of mycoplasmas as well as for early-stage mycoplasma infection diagnosis.

  5. Atmosphere

    Science.gov (United States)

    Ghosh, D.; Mitra, S. K.

    2014-05-01

    This paper investigates the high-temperature corrosion behavior of microstructurally different regions of the weldment of 9 Cr-1 Mo steel used in thermal power plant boiler in SO2 + O2 environment. The weldment is produced by tungsten inert gas welding method, and the different regions of the weldment (weld metal, heat-affected zone, and base metal) are exposed in SO2 + O2 (ratio 2:1) environment at 973 K for 120 h. The reaction kinetics and corrosion growth rate of different regions of weldment in isothermal condition are evaluated. The post corroded scales of the different specimens are studied in SEM, EDS, and XRD. The results indicate that the weld metal shows higher corrosion rate followed by HAZ and base metal. The higher rate of corrosion of weldmetal is mainly attributed to the least protective inner scale of Cr2O3 with minimum Cr Content. This is due to the formation of delta ferrite, which leads to the precipitation of the Cr-based secondary phases and depletes the free Cr from the matrix. The thermal cycles during welding at high temperature are favorable for the formation of delta ferrite. On the other hand, in absence of delta ferrite, the base metal and HAZ regions of the weldment show lower corrosion rate than weld metal. The difference in corrosion rate in the three regions of the weldment is supplemented by post-corroded scale characterizations.

  6. Calculation of radiation doses due to release of 137Cs and 131I using atmospheric dispersion and dose calculation models

    International Nuclear Information System (INIS)

    Full text: With the growing need of energy all over the world there is no doubt that nuclear energy will be an important alternative. Nuclear energy is not only a good alternative energy source but also is getting more safe. In contrary to fossil fuels nuclear energy does not produce green house gases. With all adventages of nuclear energy, the safety of nuclear power plants must be taken into care. From the radiological point of view the atmospheric dispersion of radionuclides and radiation dose calculations in case of a reactor accident is important. This study investigates the deposition and air concentration of 137Cs and 131I radionuclides and the radiation doses exposed to people living in different cities in Turkey after Chernobyl nuclear reactor accident. WRF results and HYSPLIT results were compared with observation data and the 'Atlas on the cesium deposition across Europe' that published by European Commission respectively. Both WRF and HYSPLIT results were consistent with reference data. (author)

  7. Variability of projected terrestrial biosphere responses to elevated levels of atmospheric CO2 due to uncertainty in biological nitrogen fixation

    Science.gov (United States)

    Meyerholt, Johannes; Zaehle, Sönke; Smith, Matthew J.

    2016-03-01

    Including a terrestrial nitrogen (N) cycle in Earth system models has led to substantial attenuation of predicted biosphere-climate feedbacks. However, the magnitude of this attenuation remains uncertain. A particularly important but highly uncertain process is biological nitrogen fixation (BNF), which is the largest natural input of N to land ecosystems globally. In order to quantify this uncertainty and estimate likely effects on terrestrial biosphere dynamics, we applied six alternative formulations of BNF spanning the range of process formulations in current state-of-the-art biosphere models within a common framework, the O-CN model: a global map of static BNF rates, two empirical relationships between BNF and other ecosystem variables (net primary productivity and evapotranspiration), two process-oriented formulations based on plant N status, and an optimality-based approach. We examined the resulting differences in model predictions under ambient and elevated atmospheric [CO2] and found that the predicted global BNF rates and their spatial distribution for contemporary conditions were broadly comparable, ranging from 108 to 148 Tg N yr-1 (median: 128 Tg N yr-1), despite distinct regional patterns associated with the assumptions of each approach. Notwithstanding, model responses in BNF rates to elevated levels of atmospheric [CO2] (+200 ppm) ranged between -4 Tg N yr-1 (-3 %) and 56 Tg N yr-1 (+42 %) (median: 7 Tg N yr-1 (+8 %)). As a consequence, future projections of global ecosystem carbon (C) storage (+281 to +353 Pg C, or +13 to +16 %) as well as N2O emission (-1.6 to +0.5 Tg N yr-1, or -19 to +7 %) differed significantly across the different model formulations. Our results emphasize the importance of better understanding the nature and magnitude of BNF responses to change-induced perturbations, particularly through new empirical perturbation experiments and improved model representation.

  8. Effects of a Relativistic Electron Beam Interaction with the Upper Atmosphere: Ionization, X-Rays, and Optical Emissions

    Science.gov (United States)

    Marshall, R. A.; Nicolls, M. J.; Sanchez, E. R.; Lehtinen, N. G.; Neilson, J.

    2014-12-01

    An artificial beam of relativistic (0.5--10 MeV) electrons has been proposed as an active experiment in the ionosphere and magnetosphere, with applications to magnetic field-line tracing, studies of wave-particle interactions, and beam-atmosphere interactions. The beam-atmosphere interaction, while a scientific endeavor of its own, also provides key diagnostics for other experiments. We present results of Monte Carlo simulations of the interaction of a beam of relativistic electrons with the upper atmosphere as they are injected downwards from a notional high altitude (thermospheric / ionospheric) injection platform. The beam parameters, defined by realistic parameters of a compact linear accelerator, are used to create a distribution of thousands of electrons. Each electron is injected downwards from 300 km altitude towards the dense atmosphere, where it undergoes elastic and inelastic collisions, leading to secondary ionization, optical emissions, and X-rays via bremsstrahlung. Here we describe the Monte Carlo model and present calculations of diagnostic outputs, including optical emissions, X-ray fluxes, secondary ionization, and backscattered energetic electron fluxes. Optical emissions are propagated to the ground through the lower atmosphere, including the effects of atmospheric absorption and scattering, to estimate the brightness of the emission column for a given beam current and energy. Similarly, X-ray fluxes are propagated to hypothetical detectors on balloons and satellites, taking into account Compton scattering and photoabsorption. Secondary ionization is used to estimate the radar signal returns from various ground-based radar facilities. Finally, simulated backscattered electron fluxes are measured at the injection location. The simulation results show that for realizable accelerator parameters, each of these diagnostics should be readily detectable by appropriate instruments.

  9. Study of plasma natural convection induced by electron beam in atmosphere [

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yongfeng, E-mail: yfdeng@mail.dlut.edu.cn; Han, Xianwei [Shaanxi Power Machine Design and Research Institute, Xi' an 710100 (China); Tan, Yonghua [Academy of Aerospace Propulsion Technology, Xi' an 710100 (China)

    2014-06-15

    Using high-energy electron beams to ionize air is an effective way to produce a large-size plasma in the atmosphere. In particular, with a steady-state high power generator, some unique phenomena can be achieved, including natural convection of the plasma. The characteristics of this convection are studied both experimentally and numerically. The results show that an asymmetrical temperature field develops with magnitudes that vary from 295 K to 389 K at a pressure of 100 Torr. Natural convection is greatly enhanced under 760 Torr. Nevertheless, plasma transport is negligible in this convection flow field and only the plasma core tends to move upward. Parameter analysis is performed to discern influencing factors on this phenomenon. The beam current, reflecting the Rayleigh number Ra effect, correlates with convection intensity, which indicates that energy deposition is the underlying key factor in determining such convections. Finally, natural convection is concluded to be an intrinsic property of the electron beam when focused into dense air, and can be achieved by carefully adjusting equipment operations parameters.

  10. 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

  11. Internal composition of atmospheric dust particles from focused ion-beam scanning electron microscopy.

    Science.gov (United States)

    Conny, Joseph M

    2013-08-01

    Use of focused ion-beam scanning electron microscopy (FIB-SEM) to investigate the internal composition of atmospheric particles is demonstrated for assessing particle optical properties. In the FIB-SEM instrument equipped with an X-ray detector, a gallium-ion beam mills the particle, while the electron beam images the slice faces and energy-dispersive X-ray spectroscopy provides element maps of the particle. Differences in assessments of optical behavior based on FIB-SEM and conventional SEM were shown for five selected urban dust particles. The benefit of FIB-SEM for accurately determining the depth and size of optically important phases within particles was shown. FIB-SEM revealed that iron oxide grains left undetected by conventional SEM could potentially shift the single-scattering albedo of the particle from negative to positive radiative forcing. Analysis of a coke-like particle showed that 73% of the light-scattering inclusion went undetected with conventional SEM, causing the bulk absorption coefficient to vary by as much as 25%. Optical property calculations for particles as volume-equivalent spheres and as spheroids that approximated actual particle shapes revealed that the largest effect between conventional SEM and FIB-SEM analyses was on backscattering efficiency, in some cases varying several-fold. PMID:23763344

  12. 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.

  13. Numerical simulation of atmospheric dispersion and high radiological dose zone due to accidental releases from Fukushima Power Plant

    International Nuclear Information System (INIS)

    Atmospheric dispersion calculations are made for the accidental releases of radionuclides from Fukushima Dai-ichi Nuclear Power Plant (FDNPP) using a weather model coupled Lagrangian particle dispersion model FLEXPART-WRF in a 30 km range to understand the formation of high radiation impact zone on the land region near to the FDNPP. The period during 11-17 March 2011 is considered for the study with the available source term estimates for 137Cs, 134Cs and 113I released during the accident. Simulated high resolution (1km) flow field with nested WRF model was largely westerly from 11 to 14 March. It has been found that the flow changed to northeasterly, easterly and southeasterly on 15 March under the influence of a low pressure and precipitation occurred on 15 March. Dispersion simulations showed the plume moved in a clockwise direction from Pacific Ocean to the land region to the northwest sector of Fukushima resulting in large activity depositions in that sector. The simulations show depositions of 106 to 108 Bq/m2 for 131I and 134Cs; and air dose rates of 10 μSv/h to 100 μSv/h in a distance range of 20 km in the northwest sector of Fukushima prefecture. The model could simulate the observed spike in the instantaneous air dose and its time variation at off-site monitoring stations around the reactor in reasonable agreement with highest doses at Fukushima, Litate located in the northwest sector followed by other sectors. (author)

  14. 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.

  15. 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

    ), 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......[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...

  16. 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.

  17. Stochastic electron dynamics due to drift waves in a sheared magnetic field and other drift motion problems

    International Nuclear Information System (INIS)

    Electron motion in a single electrostatic wave in a sheared magnetic field is shown to become stochastic in the presence of a second wave at an amplitude well below that obtained from the overlapping pendulum resonance approximation. The enhanced stochasticity occurs for low parallel velocity electrons for which the parallel trapping motion from eE/sub parallel//m interacts strongly with the E x B trapping motion due to the presence of magnetic shear. The guiding-center equations for single particle electron orbits in given fields are investigated using both analytical and numerical techniques. The model assumes a slab magnetic field geometry with shear and two electrostatic plane waves propagating at an angle with respect to each other. Collisions and the self-consistent effect of the electron motion upon the fields are ignored. The guiding-center motion in an inertial reference frame moving in phase with the two waves is given by a two degree-of-freedom, autonomous Hamiltonian system. The single wave particle motion may be reduced to a two parameter family of one degree-of-freedom Hamiltonians which bifurcate from a pendulum phase space to a topology with three chains of elliptic and hyperbolic fixed points separated in radius about the mode-rational surface. In the presence of a perturbing wave with a different helicity, electrons in the small parallel velocity regime become stochastic at an amplitude scaling as the fourth root of the wave potential. The results obtained for stochastic motion apply directly to the problem of electron diffusion in drift waves occurring in toroidal fusion confinement devices. The effect of an adiabatically changing radial electric field upon guiding-center orbits in tokamaks is also investigated. This perturbation causes a radial polarization drift of trapped particle tokamak orbits

  18. 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.

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

    International Nuclear Information System (INIS)

    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

  20. A computer code TERFOC-N to calculate doses to the public due to atmospheric releases of radionuclides in normal operations of nuclear facilities

    International Nuclear Information System (INIS)

    A computer code TERFOC-N has been developed to calculate doses to the public due to atmospheric releases of radionuclides in normal operations of nuclear facilities. This code calculates the highest individual dose and the collective dose from 4 exposure pathway; internal doses from ingestion and inhalation, external doses from cloudshine and groundshine. Foodchain models, which are originally referred to the U. S. Nuclear Regulatory Guide 1.109, have been improved to apply not only LWRs but also to other nuclear facilities. This report describes the employed models and the computer code, and gives a sample run performed by this code. (author)

  1. Atmospheric deposition of heavy metals due to dry, wet and occult deposition at the altitude profile Achenkirch

    International Nuclear Information System (INIS)

    The goal of this work was to determine the height dependence of the three types of deposition throughout a one year time period to be able to get information about their elevational and seasonal behavior. In the time period from October 1998 to November 1999 measurements of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn in aerosol, rain and cloud water were conducted in the Achenkirch-Valley in Tyrol, Austria. Afterwards the dry and occult deposition were modeled. The estimated annual inputs of metals at the two measurement sites Christlumkopf (1758 m a.s.l.) Mueeggerkoel (940 m a.s.l.) and the limits of the national law for protection of forest are shown. The measured depositions at both sites were far below the legal regulations. Due to the much higher occult deposition ratio at the top of the mountain the total annual input at the Christlumkopf was higher than at the Mueeggerkoel. This indicates the potential importance of occult deposition. (author)

  2. Measurement and modeling of gamma-absorbed doses due to atmospheric releases from Los Alamos Meson Physics Facility

    International Nuclear Information System (INIS)

    Short-term gamma-absorbed doses were measured by one high-pressure ionization chamber (HPIC) at an azimuth of 120 from the Los Alamos Meson Physics Facility (LAMPF) stack during the January 1 through February 8 operating cycle. Two HPICs were in the field during the September 8 through December 31 operating cycle, one north and the other north-northeast of the LAMPF stack, but they did not provide reliable data. Meteorological data were also measured at both East Gate and LAMPF. Airborne emission data were taken at the stack. Daily model predictions, based on the integration of modeled 15-min periods, were made for the first LAMPF operating cycle and were compared with the measured data. A comparison of the predicted and measured daily gamma doses due to LAMPF emissions is presented. There is very good correlation between measured and predicted values. During 39-day operating cycles, the model predicted an absorbed dose of 10.3 mrad compared with the 8.8 mrad that was measured, an overprediction of 17%

  3. Runaway electrons and x-rays from a corona discharge in atmospheric pressure air

    International Nuclear Information System (INIS)

    The characteristics of a corona discharge in atmospheric pressure air are studied using pulsed power generators that produce voltage pulses of different durations, polarities and shapes. The characteristics are measured in the single pulse, batch, and repetitively pulsed modes. It is shown that no matter what the voltage pulse polarity is, a corona discharge starts developing as a conical diffuse discharge near the electrode tip with a voltage rate of increase of ∼1015 V s-1 across an electrode of small curvature radius. With lower voltage rate of increase (∼1013 V s-1 or lower), one or several diffuse jets develop from this electrode. The diameter of the jets at their front is less than 1 mm and depends on many factors (voltage pulse amplitude and increase, inter-electrode gap width, pulse repetition rate, etc). It is found that at long voltage pulse durations, the radiation spectrum of the corona discharge changes, and the bands and lines of the material of the electrode appear in the UV region at 200-300 nm. It is demonstrated that a runaway electron beam in a corona discharge is generated and detected at a distance several times greater than the brightly glowing plasma region of the corona discharge. It is shown that x-rays are generated from a corona discharge at high pulse repetition rates of up to 1 kHz. (paper)

  4. 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.

  5. A relative risk estimation of excessive frequency of malignant tumors in population due to discharges into the atmosphere from fossil-fuel power plants and nuclear power plants

    International Nuclear Information System (INIS)

    Exposure of the population (doses to lungs, bone and whole body) due to fossil-fuel power plants (FFPP) is estimated by the example of a large modern coal FFPP taking into account the contents of 226Ra, 228Ra, 210Pb, 210Po, 40K, 232Th in the fly ash and also radon discharges. The doses produced by radionuclides mentioned above for the individuals from the population living within the range of 18km from the FFPP together with the mean collective doses all over the territory of the country used for the agricultural purposes are given. These values are compared with literary data on the doses due to discharges into the atmosphere of inert radioactive gases, 60Co, 137Cs, 90Sr and 131I from nuclear power plants (NPP). It is revealed that the total exposure risk for the near-by population due to fly ash from coal FFPP is greater by about 2 orders than the risk for individuals from the population due to the discharges from NPP at normal operating conditions. The doses produced by the discharges from FFPP working on oil are lower by 1 order than the doses due to the discharges from coal FFPP. The risk of excessive cancer frequency due to chemical carcinogens contained in the discharges from FFPP including some metals is discussed. It is noted that a more complete evaluation of the risk from NPP requires the data on the doses to the population from all the cycles of nuclear fuel production and radioactive waste disposal as well as the predicted information on collective doses per power unit of NPP due to an accident

  6. 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

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

    Science.gov (United States)

    Haser, Fritz; 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 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 and "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 and on National and International Network TV. New computer software tools allow us to roam and 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 and oceans are shown. See vortexes 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 Nino/La Nina climate changes. See the city lights, fishing fleets, gas flares and bio-mass burning of the Earth at night observed by the "night-vision" DMSP military satellite.

  8. Visions of Our Planet's Atmosphere, Land and Oceans: Electronic-Theater 2000

    Science.gov (United States)

    Hasler, A. F.

    2000-01-01

    The NASA/NOAA/AMS Earth Science Electronic Theater presents Earth science observations and visualizations in a historical perspective. Fly in from outer space to the Delaware Bay and Philadelphia area. Go back to the early weather satellite images from the 1960s see them contrasted with the latest International global satellite weather movies including killer tropical cyclones & tornadic thunderstorms. See the latest spectacular images from NASA, NOAA & UMETSAT remote sensing missions like GOES, Meteosat, NOAA, TRMM, SeaWiFS, Landsat7, & new Terra which will be visualized with state-of-the art tools. Shown in High Definition TV resolution (2048 x 768 pixels) are visualizations of hurricanes Lenny, Floyd, Georges, Mitch, Fran and Linda. see visualizations featured on covers of magazines like Newsweek, TIME, National Geographic, Popular Science and on National & International Network TV. New Digital Earth visualization tools allow us to roam & zoom through massive global images including Landsat tours of the US, and Africa with drill downs of major global cities using 1 m resolution commercialized spy-satellite technology from the Space Imaging IKONOS satellite. Spectacular new visualizations of the global atmosphere & oceans are shown. See massive dust storms sweeping across Africa. see ocean vortexes and currents that bring up the nutrients to feed tiny plankton and draw the fish, giant 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 Octane Graphics Supercomputer with dual CPUs, 5 Gigabytes of RAM and Terabyte disk using two projectors across a super sized panoramic screen.

  9. 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.

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

    International Nuclear Information System (INIS)

    We show that sharp nonmonotic variation of low temperature electron mobility μ can be achieved in GaAs/AlxGa1-xAs 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

  11. Electron beam generated in low pressure noble gas atmosphere – Compact device construction and applications

    International Nuclear Information System (INIS)

    During the process of low vacuum electron beam welding the energy of electrons is lower than the energy of electrons in the classical electron beam welding equipment. The classical electron beam welding can not always be used to weld of small work-piece details. Sometimes it’s impossible to reduce the electron beam energy because of poor focusing in the conventional electron beam welding machines. Low vacuum electron beam welding technique is well suitable to several niche products, such as thermocouples or aluminium seals. It also allows to treat the surface of dielectric materials, which is not possible using classical electron beam welding technique. The costs of low vacuum electron beam welding process are very low. (authors)

  12. 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.

  13. Atmospheric Aerosol Loading and Transport Due to the 1783-84 Laki Eruption in Iceland, Interpreted from Ash Particles and Acidity in the GISP2 Ice Core

    Science.gov (United States)

    Fiacco, R. Joseph; Thordarson, Thorvaldur; Germani, Mark S.; Self, Stephen; Palais, Julie M.; Whitlow, Sallie; Grootes, Peter M.

    1994-11-01

    Glass shards from the A.D. 1783 Laki fissure eruption in Iceland have been identified in the GISP2 ice core from Summit, Greenland, at a level just preceding the major acidity/sulfate peak. Detailed reconstruction of ice stratigraphy, coupled with analyses of solid particles from filtered samples, indicate that a small amount of Laki ash was carried via atmospheric transport to Greenland in the summer of 1783, whereas the main aerosol precipitation occurred in the summer and early fall of 1784. Sulfate concentrations in the ice increase slightly during late summer and fall of 1783 and remain steady throughout the winter due to slow oxidation rates during this season in the Arctic. The sulfate concentration rises dramatically in the spring and summer of 1784, producing a massive sulfate peak, previously believed to have accumulated during the summer of 1783 and commonly used as the marker horizon in Greenland ice core studies. The chronology of ash and acid fallout at the GISP2 site suggests that a significant portion of the Laid eruption plume penetrated the tropopause and that aerosol generated from it remained aloft for at least 1 yr after the eruption. Based on comparisons with other glaciochemical seasonal indicators, abnormally cool conditions prevailed at Summit during the summer of 1784. This further supports the claim that a significant volume of sulfate aerosol remained in the Arctic middle atmosphere well after the eruption had ceased.

  14. 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...

  15. A study of external exposure variation due to atmospheric dispersion of 41Ar Plume in Bhabha Atomic Research Centre Trombay site

    International Nuclear Information System (INIS)

    Measurement of the ambient radiation level in the surroundings of any nuclear facility is necessary to ensure the regulation and control over the environmental releases and any possible radiological impact. This is achieved in Bhabha Atomic Research Centre Trombay site using various monitoring methodologies, different Dose Logging Equipments including Radiation Early Warning System and other passive devices. During the present study (October 2009 to September 2010), external exposures due to atmospheric dispersion of 41Ar, released from Cirus and Dhruva reactors (maximum cumulative release rate 8.27E+8 Bq.s-1) were assessed by installing Gamma tracers and TLDs at different monitoring locations. TLDs were used for the measurement of cumulative environmental doses for a longer period and Gamma tracer is primarily used for dose rate measurement with provision of dose assessment of any desired period

  16. 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.

  17. Frequency effects on the electron density and {alpha}-{gamma} mode transition in atmospheric radio frequency discharges

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yuantao [Shandong Provincial Key Lab of UHV Technology and Gas Discharge Physics, School of Electrical Engineering, Shandong University, Jinan, Shandong Province 250061 (China); Cui Shaoyan [School of Mathematics and Information, Ludong University, Yantai, Shandong Province 264025 (China)

    2011-08-15

    In this paper, a one-dimensional model is explored to investigate the frequency effects on the characteristics of atmospheric radio frequency discharges at a given power. The simulation data and analytical results show that the improvement of electron density can be observed with better discharge stability by increasing excitation frequency in an appropriate range. Using the analytical equations deduced from the model, the mean electron density could be inferred by means of the measured parameters. The {alpha}-{gamma} mode transition especially in high frequency discharges is also analytically discussed based on the theoretical equations.

  18. 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

  19. 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

  20. Determination of the electron temperature in plane-to-plane He dielectric barrier discharges at atmospheric pressure

    Science.gov (United States)

    Gangwar, R. K.; Levasseur, O.; Naudé, N.; Gherardi, N.; Massines, F.; Margot, J.; Stafford, L.

    2016-02-01

    Optical emission spectroscopy (OES) measurements coupled with a collisional-radiative model were used to characterize a plane-to-plane dielectric barrier discharge at atmospheric pressure operated in nominally pure helium. The model predicts the population densities for the n  =  3 levels of He excited by electron impact processes from either ground or metastable states and takes into account excitation transfer processes between He n  =  3 levels as well as all relevant radiative decays and quenching reactions. Time-resolved OES measurements indicate that line ratios from He n  =  3 triplet states (for example, 587.5 nm-to-706.5 nm) and singlet states (for example, 667.8 nm-to-728.1 nm) first sharply rise as the discharge ignites and then slowly decrease as it extinguishes. Assuming that n  =  3 levels are first populated only by electron impact on ground state He atoms and then only by electron impact on metastable He atoms as the discharge current and thus the metastable number density rise, triplet and singlet line ratios predicted by the model become in each opposite case solely dependent on the electron temperature T e (assuming Maxwellian electron energy distribution function). The values of T e deduced from the analysis of both ratios were relatively high early in the discharge cycle (around 1.0-1.4 eV) and then much lower near discharge extinction (around 0.15 eV). For analysis of time-integrated (or cycle-averaged) OES measurements, the electron temperatures were closer to the 0.15 eV values near the end of the discharge cycle, in good agreement with the values expected from theoretical predictions in the positive columns of He glow discharges at atmospheric pressure.

  1. Observation of Diffuse Cosmic and Atmospheric Gamma Rays at Balloon Altitudes with an Electron-tracking Compton Camera

    CERN Document Server

    Takada, Atsushi; Nishimura, Hironobu; Ueno, Kazuki; Hattori, Kaori; Kabuki, Shigeto; Kurosawa, Shunsuke; Miuchi, Kentaro; Mizuta, Eiichi; Nagayoshi, Tsutomu; Nonaka, Naoki; Okada, Yoko; Orito, Reiko; Sekiya, Hiroyuki; Takeda, Atsushi; Tanimori, Toru

    2011-01-01

    We observed diffuse cosmic and atmospheric gamma rays at balloon altitudes with the Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment I (SMILE-I) as the first step toward a future all-sky survey with a high sensitivity. SMILE-I employed an electron-tracking Compton camera comprised of a gaseous electron tracker as a Compton-scattering target and a scintillation camera as an absorber. The balloon carrying the SMILE-I detector was launched from the Sanriku Balloon Center of the Institute of Space and Astronomical Science/Japan Space Exploration Agency on September 1, 2006, and the flight lasted for 6.8 hr, including level flight for 4.1 hr at an altitude of 32-35 km. During the level flight, we successfully detected 420 downward gamma rays between 100 keV and 1 MeV at zenith angles below 60 degrees. To obtain the flux of diffuse cosmic gamma rays, we first simulated their scattering in the atmosphere using Geant4, and for gamma rays detected at an atmospheric depth of 7.0 g cm-2, we found that 50% and 21% ...

  2. Coulomb blockage of conductivity in SiOx films due to single electron charging of silicon quantum dot within a chain of electronic states

    International Nuclear Information System (INIS)

    The studies of electrical characteristics of metal-oxide-semiconductor (MOS) structures with silicon nanoparticles embedded in silicon oxide were carried out. The silicon nanocrystals were formed under thermal annealing at temperature 1000 deg C of SiO2 films implanted by Si+ ions. A staircase current-voltage characteristic of a MOS structure with Si nanocrystals in SiO2 film was observed at temperature 77 K. The staircase current-voltage characteristic was well approximated in the frame of model, in which the charge transport takes place via a chain of local states, including a Si nanocrystal. The staircase-like characteristic is supposed to induced by Coulomb blockade of conducting chain of local states due to single-electron charging of the Si nanocrystal. Local states in silicon dioxide are supposed to be connected with surplus of silicon atoms. The availability of local states (charge traps) was verified by measurements of the differential capacitance and conductance in implanted MOS structures as compared to the non-implanted ones

  3. 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

  4. 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.

  5. 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.

  6. Degradation of Cu(In, Ga)Se2 thin-film solar cells due to the ionization effect of low-energy electrons

    International Nuclear Information System (INIS)

    Cu (In, Ga)Se2 (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 IIICu 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 IIICu 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. Contrast mechanism due to interface trapped charges for a buried SiO2 microstructure in scanning electron microscopy.

    Science.gov (United States)

    Zhang, Hai-Bo; Li, Wei-Qin; Wu, Dan-Wei

    2009-01-01

    We clarify the scanning electron microscopic contrast mechanism for imaging a buried SiO(2) trench microstructure with interface trapped charges by simulating both electron scattering and transport. Here, the interface trapped charges make the SiO(2) film more negatively charged and increase excess holes in the space charge distribution of the electron scattering region. The generated positive surface electric field thus redistributes some emitted secondary electrons and results in the dark contrast. This contrast mechanism is validated by comparing with experiments, and it may also provide an interesting approach for imaging and detecting deep interface trapped charges in insulating films. PMID:19029106

  8. 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...

  9. ELECTRON BEAM GENERATED IN LOW PRESSURE NOBLE GAS ATMOSPHERE – COMPACT DEVICE CONSTRUCTION AND APPLICATIONS

    OpenAIRE

    Zawada, Aleksander; Konarski, Piotr

    2013-01-01

    Simple and compact design of prototype electron beam welding machine is presented. The instrument allows welding of typical materials as metals and alloys. It can be used also for surface melting of insulators like glass and ceramic. Electron beam source uses hollow cathode of 20 mm diameter and operates in the pressure between 0.001 to 0.1 Torr of noble gas, with the work-piece positioned at 30 mm distance from the cathode. Focussing of the electron beam is provided by curvature and...

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

    International Nuclear Information System (INIS)

    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

  11. Phase-space holes due to electron and ion beams accelerated by a current-driven potential ramp

    Directory of Open Access Journals (Sweden)

    M. V. Goldman

    2003-01-01

    Full Text Available One-dimensional open-boundary simulations have been carried out in a current-carrying plasma seeded with a neutral density depression and with no initial electric field. These simulations show the development of a variety of nonlinear localized electric field structures: double layers (unipolar localized fields, fast electron phase-space holes (bipolar fields moving in the direction of electrons accelerated by the double layer and trains of slow alternating electron and ion phase-space holes (wave-like fields moving in the direction of ions accelerated by the double layer. The principal new result in this paper is to show by means of a linear stability analysis that the slow-moving trains of electron and ion holes are likely to be the result of saturation via trapping of a kinetic-Buneman instability driven by the interaction of accelerated ions with unaccelerated electrons.

  12. Cold atmospheric pressure plasma jets: Interaction with plasmid DNA and tailored electron heating using dual-frequency excitation

    International Nuclear Information System (INIS)

    Recent progress in plasma science and technology has enabled the development of a new generation of stable cold non-equilibrium plasmas operating at ambient atmospheric pressure. This opens horizons for new plasma technologies, in particular in the emerging field of plasma medicine. These non-equilibrium plasmas are very efficient sources for energy transport through reactive neutral particles (radicals and metastables), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. The effect of a cold radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. The formation of double strand breaks correlates well with the atomic oxygen density. Taken with other measurements, this indicates that neutral components in the jet are effective in inducing double strand breaks. Plasma manipulation techniques for controlled energy delivery are highly desirable. Numerical simulations are employed for detailed investigations of the electron dynamics, which determines the generation of reactive species. New concepts based on nonlinear power dissipation promise superior strategies to control energy transport for tailored technological exploitations.

  13. Cold atmospheric pressure plasma jets: Interaction with plasmid DNA and tailored electron heating using dual-frequency excitation

    Energy Technology Data Exchange (ETDEWEB)

    Niemi, K.; O' Neill, C.; Cox, L. J.; Waskoenig, J.; Hyland, W. B.; McMahon, S. J.; Reuter, S.; Currell, F. J.; Graham, W. G.; O' Connell, D.; Gans, T. [Centre for Plasma Physics, Queen' s University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom)

    2012-05-25

    Recent progress in plasma science and technology has enabled the development of a new generation of stable cold non-equilibrium plasmas operating at ambient atmospheric pressure. This opens horizons for new plasma technologies, in particular in the emerging field of plasma medicine. These non-equilibrium plasmas are very efficient sources for energy transport through reactive neutral particles (radicals and metastables), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. The effect of a cold radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. The formation of double strand breaks correlates well with the atomic oxygen density. Taken with other measurements, this indicates that neutral components in the jet are effective in inducing double strand breaks. Plasma manipulation techniques for controlled energy delivery are highly desirable. Numerical simulations are employed for detailed investigations of the electron dynamics, which determines the generation of reactive species. New concepts based on nonlinear power dissipation promise superior strategies to control energy transport for tailored technological exploitations.

  14. Cold atmospheric pressure plasma jets: Interaction with plasmid DNA and tailored electron heating using dual-frequency excitation

    Science.gov (United States)

    Niemi, K.; O'Neill, C.; Cox, L. J.; Waskoenig, J.; Hyland, W. B.; McMahon, S. J.; Reuter, S.; Currell, F. J.; Graham, W. G.; O'Connell, D.; Gans, T.

    2012-05-01

    Recent progress in plasma science and technology has enabled the development of a new generation of stable cold non-equilibrium plasmas operating at ambient atmospheric pressure. This opens horizons for new plasma technologies, in particular in the emerging field of plasma medicine. These non-equilibrium plasmas are very efficient sources for energy transport through reactive neutral particles (radicals and metastables), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. The effect of a cold radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. The formation of double strand breaks correlates well with the atomic oxygen density. Taken with other measurements, this indicates that neutral components in the jet are effective in inducing double strand breaks. Plasma manipulation techniques for controlled energy delivery are highly desirable. Numerical simulations are employed for detailed investigations of the electron dynamics, which determines the generation of reactive species. New concepts based on nonlinear power dissipation promise superior strategies to control energy transport for tailored technological exploitations.

  15. Electron Tomography of Nanoparticle Clusters: Implications for Atmospheric Lifetimes and Radiative Forcing of Soot

    Science.gov (United States)

    vanPoppel, Laura H.; Friedrich, Heiner; Spinsby, Jacob; Chung, Serena H.; Seinfeld, John H.; Buseck, Peter R.

    2005-01-01

    Nanoparticles are ubiquitous in nature. Their large surface areas and consequent chemical reactivity typically result in their aggregation into clusters. Their chemical and physical properties depend on cluster shapes, which are commonly complex and unknown. This is the first application of electron tomography with a transmission electron microscope to quantitatively determine the three-dimensional (3D) shapes, volumes, and surface areas of nanoparticle clusters. We use soot (black carbon, BC) nanoparticles as an example because it is a major contributor to environmental degradation and global climate change. To the extent that our samples are representative, we find that quantitative measurements of soot surface areas and volumes derived from electron tomograms differ from geometrically derived values by, respectively, almost one and two orders of magnitude. Global sensitivity studies suggest that the global burden and direct radiative forcing of fractal BC are only about 60% of the value if it is assumed that BC has a spherical shape.

  16. 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.

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

    International Nuclear Information System (INIS)

    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.

  18. Solar flare soft-X-ray spectra from Very Low Frequency observations of ionospheric modulations: Possibility of uninterrupted observation of non-thermal electron-plasma interaction in solar atmosphere.

    Science.gov (United States)

    Palit, Sourav; Chakrabarti, Sandip Kumar; Ray, Suman

    2016-07-01

    The hard and soft X-ray regions of a solar flare spectrum are the manifestation of interaction, namely of bremsstrahlung radiation of the non-thermal electrons moving inward in the denser part of the solar atmosphere with the plasma heated by those energetic electrons. The continuous and uninterrupted knowledge of X-ray photon spectra of flares are of great importance to derive information on the electron acceleration and hence time-evolution of energy transport and physics during solar flares. Satellite observations of solar X-ray spectrum are often limited by the restricted windows in each duty cycle to avoid the interaction of detectors and instruments with harmful energetic charge particles. In this work we have tried to tackle the problem by examining the possibility of using Earth's ionosphere and atmosphere as the detector of such transient events. Earth's lower ionosphere and upper atmosphere are the places where the X-rays and gamma-rays from such astronomical sources are absorbed. The electron-ion production rates due to the ionization of such energetic photons at different heights depend on the intensity and wavelength of the injected spectra and hence vary from one source to another. Obviously the electron and ion density vs. altitude profile has the imprint of the incident photon spectrum. As a preliminary exercise we developed a novel deconvolution method to extract the soft X-ray part of spectra of some solar flares of different classes from the electron density profiles obtained from Very Low Frequency (VLF) observation of lower ionosphere during those events. The method presented here is useful to carry out a similar exercise to infer the higher energy part of solar flare spectra and spectra of more energetic events such as the GRBs, SGRs etc. with the possibilities of probing even lower parts of the atmosphere.

  19. Soft x-ray bremsstrahlung and flourescent line production in the atmosphere by low energy electrons

    International Nuclear Information System (INIS)

    Several clues, such as pulse height distribution and angular distribution, that reveal the presence of low energy quasi-trapped or precipitating electrons capable of by-passing magnetic rejection schemes and penetrating the counter windows of soft x-ray detectors are discussed. (U.S.)

  20. Response in electrostatic analyzers due to backscattered electrons: case study analysis with the Juno Jovian Auroral Distribution Experiment-Electron instrument.

    Science.gov (United States)

    Clark, G; Allegrini, F; Randol, B M; McComas, D J; Louarn, P

    2013-10-01

    In this study, we introduce a model to characterize electron scattering in an electrostatic analyzer. We show that electrons between 0.5 and 30 keV scatter from internal surfaces to produce a response up to ~20% of the ideal, unscattered response. We compare our model results to laboratory data from the Jovian Auroral Distribution Experiment-Electron sensor onboard the NASA Juno mission. Our model reproduces the measured energy-angle response of the instrument well. Understanding and quantifying this scattering process is beneficial to the analysis of scientific data as well as future instrument optimization. PMID:24182165

  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. 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.; Fraser-Smith, A.C.; Wiliamson, P.R.; Raitt, W.J.; Myers, N.B.; Sasaki, S.

    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......) and down-going differential energy flux. The equations are solved numerically,using the MSIS atmospheric model and the IRI ionospheric model, yielding estimates of the differential electron energy flux density at the spacecraft location. At altitudes below 200-250 km and forbeam energies around 1 ke......V, it is shown that secondary electrons supply a significant contribution to the return current to the spacecraft and thereby reduce the spacecraft potential. Our numerical results are in good agreement with observations from the CHARGE-2 sounding rocket experiment.A more detailed study of the BAI as it...

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

    International Nuclear Information System (INIS)

    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. Mars Global Surveyor Radio Science Electron Density Profiles: Interannual Variability and Implications for the Neutral Atmosphere

    Science.gov (United States)

    Bougher, S. W.; Engel, S.; Hinson, D. P.; Murphy, J. R.

    2003-01-01

    The Mars Global Surveyor (MGS) Radio Science (RS) experiment employs an ultrastable oscillator aboard the spacecraft. The signal from the oscillator to Earth is refracted by the Martian ionosphere, allowing retrieval of electron density profiles versus radius and geopotential. The present analysis is carried out on five sets of occultation measurements: (1) four obtained near northern summer solstice (Ls = 74-116, near aphelion) at high northern latitudes (64.7-77.6N), and (2) one set of profiles approaching equinox conditions (Ls = 135- 146) at high southern latitudes (64.7-69.1S). Electron density profiles (95 to 200 km) are examined over a narrow range of solar zenith angles (76.5-86.9 degrees) for local true solar times of (1) 3-4 hours and (2) 12.1 hours. Variations spanning 1-Martian year are specifically examined in the Northern hemisphere.

  5. 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...

  6. Verification of electron doping in single-layer graphene due to H2 exposure with thermoelectric power

    International Nuclear Information System (INIS)

    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 H2 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

  7. Polarized light emission after grazing ion-surface scattering due to capture of spin-polarized electrons

    Energy Technology Data Exchange (ETDEWEB)

    Winter, H.; Hagedorn, H.; Zimny, R.; Nienhaus, H.; Kirschner, J.

    1989-01-16

    We have observed the capture of polarized electrons into excited terms of atoms after the interaction of fast ions with a magnetized Fe(110) surface at grazing incidence. The spin polarization of captured electrons results in a modified circular polarization fraction of fluorescence light. This experiment has considerable potential as a new analytical tool for investigating surface magnetism with extreme surface sensitivity, as a method for detailed studies of ion-surface interaction, and as a means to produce nuclear spin-polarized beams.

  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. On the generation and disruption of a picosecond runaway electron beam during the breakdown of an atmospheric-pressure gas gap

    Energy Technology Data Exchange (ETDEWEB)

    Barengolts, S. A. [Prokhorov General Physics Institute, RAS, 38 Vavilov St., 119991 Moscow (Russian Federation); Mesyats, G. A.; Tsventoukh, M. M. [Lebedev Physical Institute, RAS, 53 Leninsky Ave., 119991 Moscow (Russian Federation); Uimanov, I. V. [Institute of Electrophysics, RAS, 106 Amundsen St., 620016 Ekaterinburg (Russian Federation)

    2012-03-26

    The generation and disruption of the picosecond runaway electron beam in atmospheric pressure strongly overvolted gas gap is considered with emphasis on the runaway kinetics, the increase in emission current and plasma density, and beam instabilities. It has been shown that a few-nanosecond ten-kV prepulse gives rise to a streamer. Application of the main pulse ({approx}2 MV/ns) results in the runaway electron beam generation with the streamer electrons involved in the acceleration, and in increase of the electron emission from the cathode and the plasma density. At the high enough plasma density, fast beam instability disrupts the runaway electron beam.

  10. 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

  11. 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

  12. 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.

  13. Atmospheric Neutrino Status

    CERN Document Server

    O'Sullivan, E

    2016-01-01

    This conference proceeding discusses new results arising from atmospheric neutrino detection in the Super-Kamiokande and IceCube experiments. Super-Kamiokande has measured atmospheric neutrinos in the energy range of 100 MeV-10 TeV and uses this data set to conclusively measure the east-west effect to 8.0 (6.0) $\\sigma$ for electron (muon) neutrinos. IceCube is ideal for measuring high energy atmospheric neutrinos and has explored how different production channels for atmospheric neutrinos contribute to the total overall observed flux. The measurement is consistent with the conventional spectrum, produced by the decay of pions and kaon, while the contribution from the prompt channel (due to charm decay) is consistent with zero.

  14. Sub-60 deg. C atmospheric helium-water plasma jets: modes, electron heating and downstream reaction chemistry

    International Nuclear Information System (INIS)

    For plasma treatment of many heat-labile materials (e.g. living tissues) that either are moist or contain a surface layer of liquid, it is desirable that the gas plasma is generated at atmospheric pressure for process convenience and with a gas temperature ideally no more than 60 deg. C for mitigating permanent damage to the integrity of the test material. This implies that the liquid-containing plasma needs to be of low dissipated electrical energy and that plasma treatment should be based largely on non-equilibrium reaction chemistry. In this paper, a class of sub-60 deg. C atmospheric helium-water plasma jets is studied in terms of their main physiochemical properties. It is shown that there are five distinct modes appearing in the sequence of, with increasing voltage, the first chaotic mode, the plasma bullet mode, the second chaotic mode, the abnormal glow mode and the non-thermal arc mode. Its chaotic modes may be sustained over a wide range of water vapour concentrations (0-2500 ppm). Compared with other liquid-containing plasmas, the He-H2O plasma jet operated below its non-thermal arc mode has several distinct advantages, namely very low energy consumption (2-10 μJ per pulse), sub-60 deg. C gas temperature, electron-modulated production of He, N2, N2+, O*, H and OH(A-X), and low ozone production (0.1-0.4 ppm). These results provide a first attempt at the landscape of the physiochemical characteristics in atmospheric He-H2O plasma jets.

  15. Perturbation of the energy loss spectra for an accelerated electron beam due to the photo injector exit

    CERN Document Server

    Salah, W

    2003-01-01

    The influence of the photo-injector exit hall on the energy loss for an accelerated electron beam is investigated, by calculating the total energy transferred from the electrons to the wakefields, which are driven by the beam. The obtained energy loss is compared to those previously obtained for a 'pill-box' cavity. This comparison shows that the influence of this hall, in terms of energy loss, varies over the beam length. It is strongest in the middle of the beam and decreases towards both ends. In consequence of this perturbation, the center of the beam is displaced from its initial position during the first phase (t < 200 ps) where the exit aperture has no effect to a new equilibrium position which takes place at 200 < t < 250 ps. (author)

  16. Investigating ionisation cluster size distribution due to sub-1 keV electrons in view of Heisenberg's Uncertainty

    Science.gov (United States)

    Li, B.; Palmans, H.; Hao, L.; Nisbet, A.

    2015-09-01

    As the wavelengths of low energy electrons become comparable with the length scale of the mean ionisation step size, each event particle should be treated with care as the condition outlined in Heisenberg's uncertainty principle (HUP) should also be satisfied. Within this quantum-classical regime, spatial delocalisations of individual ionisation event sites that are generated outside the target region are calculated, and particular attention is given to the validity of using classical transport methods in simulations of nanodosimetric parameters such as mean cluster size, first and second moments, variance and cumulative frequency of ionisation cluster-size probability distributions. This paper presents the comparison between conventionally calculated nanodosimetric quantities and the ones where interacting particles are treated semi-classically with spatial uncertainties satisfied by HUP. The simulated primary charged particles are electrons of energies between 100 eV and 1 keV in DNA equivalent target aqueous water volumes using GEANT4-DNA.

  17. Temperature rise of a metal target due to energy transfer from a high power density electron beam

    International Nuclear Information System (INIS)

    Electron beam welding has been industrially used since the early sixties. The processes of energy absorption, material removal and deep penetration, which are different to other welding techniques, are not explicitly solved. According to the physical conception of the energy absorption the temperature rise of the area of impact will be calculated with means of a computer program. The power density stipulates an explosion of the material, which can be experimentally prosecuted in intervals of 2 - 5.10-5s. (author)

  18. Inhibition of type III radio emissions due to the interaction between two electron beams: Observations and simulations

    OpenAIRE

    Briand, C; Henri, P.; Hoang, S

    2014-01-01

    We report the peculiar interaction of two type III bursts observed in the solar wind. As electronbeams propagating on the same magnetic field lines cross, a spectacular depletion of the type III radioemission is observed. We combine observations from the WAVES experiment on board the STEREO missiontogether with kinetic plasma simulations to study the extinction of type III radio emission resulting fromthe interaction between two electron beams. The remote observations enable to follow the ele...

  19. 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.

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

    International Nuclear Information System (INIS)

    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

  1. 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

  2. Atmospheric and geomagnetic influence on thermospheric electron densities investigated by oblique radio sounding

    International Nuclear Information System (INIS)

    Complete text of publication follows. Mid-latitude HF sounder paths of ∼2400km are operating between New Zealand and Australia. The maximum observed frequencies, and hence electron densities at thermospheric altitudes, are compared with statistical predictions from a climatological HF radio propagation model which uses a database of vertical soundings. Variations from predicted median lower and upper decile frequencies, may be interpreted in terms of ionospheric and geomagnetic activity. Initial results indicate the dependence, of ionisation variations from the model, is at least as strong for neutral thermospheric variations as for geomagnetic variations. Closely spaced multiple paths provide opportunities to investigate F2 layer ionisation variations, inside the traditional 300km correlation scale. Preliminary investigations have also been made for long paths into high-latitudes from Australia to Antarctica using a new highly sensitive receiver.

  3. N2O analysis in the atmosphere via electron capture-gas chromatography

    Science.gov (United States)

    Rasmussen, R. A.; Krasnec, J.; Pierotti, D.

    1976-01-01

    The potential of commercially available pulse-modulated electron capture detector (ECD)-equipped gas chromatographs for direct measurement of ambient levels of N2O is assessed. Since the sensitivity of ECD to N2O is directly proportional to the detector operating temperature and detector standing current, it is necessary to use a 'hot' ECD (250-350 C). The method is shown to be very precise with a standard error not exceeding 1% for automated analysis of ambient air samples. The technology is available to permit highly accurate routine direct analysis of N2O in the troposphere and stratosphere. Both captured air samples or direct real-time measurement from research vessels or airborne platforms are possible.

  4. An economic analysis of the abatement of pollution due to flue gas stacks of industrial, electrical plants and of incinerators using electrical discharges, ozone and electron beam

    International Nuclear Information System (INIS)

    There are numerous of investigations, many reports and a lot of industrial applications for simultaneous reduction of SO2 and NOx from flue gas stack emission by electron beam induced plasma process. When ammonia is applied under electron beam bombardment, concentration decreases to zero, and it is also accompanied by salt formation, i.e. ammonium sulphate and ammonium nitrate. This efficient technology, requires high costs for investment and has been applied in only few countries until now (Japan, China, USA, Poland). There are a lot of small countries, consumers of cheap combustibles, which produce large quantities of atmospheric pollutants such as SO2 and NOx. For this reason there is a great interest for the implementation of cheaper technologies with a similar impact as electron beam processing. In this paper we have given a lot of experimental data for SO2 and NOx removal by means of electron beams, electrical discharge and ozone, both in stand alone and in hybrid systems and, also, a comparison with the results obtained by other laboratories.The applications of new technologies are presented with an Economic Analysis of the efficiency

  5. 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; Protsenko, I. E.; Kardynal, Beata; Lavrinenko, Andrei

    2014-01-01

    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. Such......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...

  6. Can fractional quantum Hall effect be due to the formation of coherent wave structures in a 2D electron gas?

    Science.gov (United States)

    Mirza, Babur M.

    2016-05-01

    A microscopic theory of integer and fractional quantum Hall effects is presented here. In quantum density wave representation of charged particles, it is shown that, in a two-dimensional electron gas coherent structures form under the low temperature and high density conditions. With a sufficiently high applied magnetic field, the combined N particle quantum density wave exhibits collective periodic oscillations. As a result the corresponding quantum Hall voltage function shows a step-wise change in multiples of the ratio h/e2. At lower temperatures further subdivisions emerge in the Hall resistance, exhibiting the fractional quantum Hall effect.

  7. Numerical and experimental study of the load of an object due to the effects of a flow field in the atmospheric boundary layer

    Czech Academy of Sciences Publication Activity Database

    Michalcová, V.; Kuznetsov, Sergeii; Pospíšil, S.

    2014-01-01

    Roč. 8, č. 1 (2014), s. 135-140. ISSN 1998-0159 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0060 Institutional support: RVO:68378297 Keywords : atmospheric boundary layer ABL * bluff body * CFD * ELES * SAS * wind tunnel Subject RIV: JM - Building Engineering http://www.naun.org/cms.action?id=7632

  8. 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...

  9. Accelerated cathodic reaction in microbial corrosion of iron due to direct electron uptake by sulfate-reducing bacteria

    International Nuclear Information System (INIS)

    Highlights: ► Corrosive SRB strain accelerates cathodic reaction of iron by direct electron uptake. ► Hydrogenotrophic control strain does not influence the cathodic reaction. ► Deposited ferrous sulfides do not stimulate the cathodic reaction. ► Deposited ferrous sulfides mediate electrical contact between metal and cells. - Abstract: Microbially influenced iron corrosion by sulfate-reducing bacteria (SRB) is conventionally attributed to the chemical corrosiveness of H2S, facilitated abiotic H+-reduction at deposited FeS, and biological consumption of chemically formed (‘cathodic’) H2. However, recent studies with corrosive SRB indicated direct consumption of iron-derived electrons rather than of H2 as a crucial mechanism. Here, we conducted potentiodynamic measurements with iron electrodes colonized by corrosive SRB. They significantly stimulated the cathodic reaction, while non-corrosive yet H2-consuming control SRB had no effect. Inactivation of the colonizing bacteria significantly reduced current stimulation, thus confirming biological catalysis rather than an abiotic cathodic effect of FeS.

  10. 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

  11. Power dissipation, gas temperatures and electron densities of cold atmospheric pressure helium and argon RF plasma jets

    International Nuclear Information System (INIS)

    A set of diagnostic methods to obtain the plasma parameters including power dissipation, gas temperature and electron density is evaluated for an atmospheric pressure helium or argon radio frequency (RF) plasma needle for biomedical applications operated in open air. The power density of the plasma is more or less constant and equal to 1.3 × 109 W m−3. Different methods are investigated and evaluated to obtain the gas temperature. In this paper the gas temperatures obtained by rotational spectra of OH(A–X) and N2+ (B–X) are compared with Rayleigh scattering measurements and measurements of the line broadening of hydrogen and helium emission lines. The obtained gas temperature ranges from 300 to 650 K, depending on the gas. The electron densities are estimated from the Stark broadening of the hydrogen α and β lines which yield values between 1019 and 1020 m−3. In the case of helium, this is an overestimate as is shown by a power balance from the measured power density in the plasma jet. The obtained plasma parameters enable us to explain the radial contraction of the argon plasma compared with the more diffuse helium plasma. The accuracy of all considered diagnostics is discussed in detail.

  12. Comparison of the generation of interface states in MOS structures due to 60Co and VUV irradiation accompanied with photo-injection of electrons

    International Nuclear Information System (INIS)

    The buildup of interface states in MOS structures with differently annealed oxides is studied under vacuum ultraviolet (VUV) and 60Co irradiation. A larger creation of interface states is observed if photoinjection of electrons is applied simultaneously with the VUV irradiation. The presence of electrons at the Si/SiO2 interface favors the generation and explains the larger amount of interface states after 60Co irradiation. After VUV irradiation the interface state density increases in n-samples to a specific saturation value which is reached earlier if gate voltage is made more positive or samples are exposed to photoinjection. This is due to the increase of the radiation peak which is located in the upper half of the silicon gap. The impact of post oxidation annealing on the interface state generation is investigated due to VUV and 60Co irradiation. (author). 26 refs., 9 figs., 1 tab

  13. 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.

  14. On the thermal conductivity due to collisions between relativistic degenerate electrons. [for stellar opacity calculations and propagation of deflagration fronts of compact stellar remnants

    Science.gov (United States)

    Timmes, F. X.

    1992-01-01

    A numerical integration is undertaken of the integral expression for the thermal conductivity due to collisions of relativistic degenerate electrons and compared to the limiting-case analytic formula. The integration is designed to encompass all temperature/electron-plasma-frequency temperature ratios between the melting temperature and the Fermi temperature. High accuracy fits are demonstrated by interpolating the values of the integrals of the function and by using an asymptotic function by Urpin and Yakovlev (1980). The numerically integrated expression compares favorably to the limiting-case analytic asymptotic formula by Urpin and Yakovlev, and the results are valid for temperatures above and below the electron-plasma-frequency temperature. The present techniques can be used in stellar opacity calculations and in the study of the propagation of deflagration fronts of compact stellar remnants.

  15. Reliability of Raman measurements of thermal conductivity of single-layer graphene due to selective electron-phonon coupling: A first-principles study

    Science.gov (United States)

    Vallabhaneni, Ajit K.; Singh, Dhruv; Bao, Hua; Murthy, Jayathi; Ruan, Xiulin

    2016-03-01

    Raman spectroscopy has been widely used to measure thermal conductivity (κ ) of two-dimensional (2D) materials such as graphene. This method is based on a well-accepted assumption that different phonon polarizations are in near thermal equilibrium. However, in this paper, we show that, in laser-irradiated single-layer graphene, different phonon polarizations are in strong nonequilibrium, using predictive simulations based on first principles density functional perturbation theory and a multitemperature model. We first calculate the electron cooling rate due to phonon scattering as a function of the electron and phonon temperatures, and the results clearly illustrate that optical phonons dominate the hot electron relaxation process. We then use these results in conjunction with the phonon scattering rates computed using perturbation theory to develop a multitemperature model and resolve the spatial temperature distributions of the energy carriers in graphene under steady-state laser irradiation. Our results show that electrons, optical phonons, and acoustic phonons are in strong nonequilibrium, with the flexural acoustic (ZA) phonons showing the largest nonequilibrium to other phonon modes, mainly due to their weak coupling to other carriers in suspended graphene. Since ZA phonons are the main heat carriers in graphene, we estimate that neglecting this nonequilibrium leads to underestimation of thermal conductivity in experiments at room temperature by a factor of 1.35 to 2.6, depending on experimental conditions and assumptions used. Underestimation is also expected in Raman measurements of other 2D materials when the optical-acoustic phonon coupling is weak.

  16. 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.

  17. Influence of complex impact of the picosecond electron beam and volume discharge in atmospheric-pressure air on the electronic properties of MCT epitaxial films surface

    Science.gov (United States)

    Grigoryev, Denis V.; Novikov, Vadim A.; Bezrodnyy, Dmitriy A.; Tarasenko, Viktor F.; Shulepov, Michail A.; Dvoretskii, Sergei A.

    2015-12-01

    In the present report we studied the distribution of surface potential of the HgCdTe epitaxial films grown by molecular beam epitaxy after the impact of picosecond electron beam and volume discharge in atmospheric-pressure air. The surface potential distribution was studied by the Kelvin Force Probe Microscopy. The experimental data obtained for the variation of the contact potential difference (ΔCPD) between the V-defect and the main matrix of the epitaxial film. The investigation of the origin epitaxial films show that variation of the spatial distribution of surface potential in the V-defect region can be related to the variation of the material composition. The experimental data obtained for the irradiated samples show that the mean value of ΔCPD for the original surface differs from the one for the irradiated surface for 55 eV. At the same time the mean value of ΔCPD changes its sign indicating that the original surface of the epitaxial HgCdTe film predominantly contains the grains with increased cadmium content while after the irradiation the grains possess an increased content of mercury. Therefore, during the irradiation process a decrease of the mercury content in the near-surface region of the semiconductor takes place resulting in the alteration of the electrophysical properties in the films near-surface region.

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

    International Nuclear Information System (INIS)

    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

  19. 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.

  20. Simulation of equivalent dose due to accidental electron beam loss in Indus-1 and Indus-2 synchrotron radiation sources using FLUKA code

    International Nuclear Information System (INIS)

    Indus-1 and Indus-2 are two Synchrotron radiation sources at Raja Ramanna Centre for Advanced Technology (RRCAT), India. Stored electron energy in Indus-1 and Indus-2 are 450MeV and 2.5GeV respectively. During operation of storage ring, accidental electron beam loss may occur in addition to normal beam losses. The Bremsstrahlung radiation produced due to the beam losses creates a major radiation hazard in these high energy electron accelerators. FLUKA, the Monte Carlo radiation transport code is used to simulate the accidental beam loss. The simulation was carried out to estimate the equivalent dose likely to be received by a trapped person closer to the storage ring. Depth dose profile in water phantom for 450MeV and 2.5GeV electron beam is generated, from which percentage energy absorbed in 30cm water phantom (analogous to human body) is calculated. The simulation showed the percentage energy deposition in the phantom is about 19% for 450MeV electron and 4.3% for 2.5GeV electron. The dose build up factor in 30cm water phantom for 450MeV and 2.5GeV electron beam are found to be 1.85 and 2.94 respectively. Based on the depth dose profile, dose equivalent index of 0.026Sv and 1.08Sv are likely to be received by the trapped person near the storage ring in Indus-1 and Indus-2 respectively. (author)

  1. Atmospheric dispersion simulations of radioactive materials discharged from the Fukushima Daiichi Nuclear Power Plant due to accident. Consideration of deposition process

    International Nuclear Information System (INIS)

    In order to assess the radiological dose to the public resulting from the Fukushima Daiichi Nuclear Power Plant accident in Japan, the spatial and temporal distribution of radioactive materials in the environment have been analyzed by computer simulations. As the first step, the source term of radioactive materials discharged into the atmosphere was estimated by coupling environmental monitoring data with atmospheric dispersion simulations by the System for Prediction of Environmental Emergency Dose Information (SPEEDI) and the Worldwide version of SPEEDI (WSPEEDI-II). By using the estimated source term, detailed analysis on the local dispersion around the plant and regional scale dispersion over the eastern Japan area were carried out by WSPEEDI-II simulations. The formation processes of high dose rate zone around north-west direction from the plant and deposition over the eastern Japan area were reproduced in these simulations. However, there were some discrepancies between calculation and airborne monitoring of surface deposition of 137Cs, and the cause of these discrepancies was investigated. The result of parametric study indicated that the model can reproduce the spatial and temporal distribution of radioactive materials in the environment more accurately by using different wet deposition schemes considering rainout/washout, ice/liquid phases, and fog deposition. (author)

  2. Measurement of Electron Density and Ion Collision Frequency with Dual Assisted Grounded Electrode DBD in Atmospheric Pressure Helium Plasma Jet

    Science.gov (United States)

    Zhou, Qiujiao; Qi, Bing; Huang, Jianjun; Pan, Lizhu; Liu, Ying

    2016-04-01

    The properties of a helium atmospheric-pressure plasma jet (APPJ) are diagnosed with a dual assisted grounded electrode dielectric barrier discharge device. In the glow discharge, we captured the current waveforms at the positions of the three grounded rings. From the current waveforms, the time delay between the adjacent positions of the rings is employed to calculate the plasma bullet velocity of the helium APPJ. Moreover, the electron density is deduced from a model combining with the time delay and current intensity, which is about 1011 cm‑3. In addition, The ion-neutral particles collision frequency in the radial direction is calculated from the current phase difference between two rings, which is on the order of 107 Hz. The results are helpful for understanding the basic properties of APPJs. supported by National Natural Science Foundation of China (No. 11105093), the Technological Project of Shenzhen, China (No. JC201005280485A), and the Planned S&T Program of Shenzhen, China (No. JC201105170703A)

  3. Oven atmosphere influence on the defects elimination in tile ceramics

    International Nuclear Information System (INIS)

    Ceramic tiles show defects after firing due to reaction of transition metals with atmosphere at high temperatures. These defects (differential colors at surface) can be eliminated by skin atmosphere control. Test samples obtained from industrial composition with addition of transition metal oxides were heat treated in different atmospheres. The samples were analysed by X-ray diffraction, scanning electron microscopy and thermal analysis to evaluate the effect of transition metals and firing atmosphere in defect formation. The results showed that skin atmosphere and organic matter concentration play an important role in the differential color formation due to transition metals reduction or metal carbide formation. (author)

  4. The impact of turbulence intensity and atmospheric stability on power deficits due to wind turbine wakes at Horns Rev wind farm

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose; Barthelmie, Rebecca J.; Jensen, Leo E.;

    2012-01-01

    the flow inside the wind farm, and the power deficits along rows of wind turbines have been determined for different inflow directions and wind speed intervals. A method to classify the atmospheric stability based on the Bulk-Ri number has been implemented. Long-term stability conditions have been...... unstable conditions, whereas northerly winds have fewer observations in the stable classes. Stable conditions also tend to be associated with lower levels of turbulence intensity, and this relationship persists as wind speeds increase. Power deficit is a function of ambient turbulence intensity. The level...... of power deficit is strongly dependent on the wind turbine spacing; as turbulence intensity increases, the power deficit decreases. The power deficit is determined for four different wind turbine spacing distances and for stability classified as very stable, stable and others (near neutral to very...

  5. Assessment of atmospheric contamination over United States due to radionuclides' release from Japanese Fukushima Dai-Ichi Nuclear Reactor during March, 2011 using HYSPLIT model

    International Nuclear Information System (INIS)

    This study is an assessment of continental-scale contamination of radionuclides release from Fukushima Dai-ichi nuclear power plant in Japan during 12-31 March 2011 affecting the United States of America, a part of North American continent. HYSPLIT model, driven by daily NCEP global meteorological data was used to produce forward trajectories to estimate the transport time for the Fukushima plant releases to reach the west coast of USA and to estimate the concentration deposition of the radionuclides at select locations over the west coast of USA. The model estimates were compared with respective monitored values for validation. This study brings out the transport time to reach US west coast from the Japanese plant site to be about 6-7 days indicating a speedy movement under favourable atmospheric flow patterns (wind). (author)

  6. Regulation of electron transport in C(3) plant chloroplasts in situ and in silico: short-term effects of atmospheric CO(2) and O(2).

    Science.gov (United States)

    Kuvykin, Ilya V; Ptushenko, Vasily V; Vershubskii, Alexey V; Tikhonov, Alexander N

    2011-03-01

    In this work, we have investigated the effects of atmospheric CO(2) and O(2) on induction events in Hibiscus rosa-sinensis leaves. These effects manifest themselves as multiphase kinetics of P(700) redox transitions and non-monotonous changes in chlorophyll fluorescence. Depletion of CO(2) and O(2) in air causes a decrease in linear electron flux (LEF) and dramatic lowering of P(700)(+) level. This is explained by the impediment to electron efflux from photosystem 1 (PS1) at low acceptor capacity. With the release of the acceptor deficit, the rate of LEF significantly increases. We have found that oxygen promotes the outflow of electrons from PS1, providing the rise of P(700)(+) level. The effect of oxygen as an alternative electron acceptor becomes apparent at low and ambient concentrations of atmospheric CO(2) frames of our mathematical model. The model describes the reciprocal changes in LEF and NPQ and predicts the redistribution of electron fluxes on the acceptor side of PS1. In particular, the contribution of cyclic electron flow around PS1 (CEF1) and water-water cycle gradually decays during the induction phase. This result is consistent with experimental data indicating that under the steady-state conditions the contribution of CEF1 to photosynthetic electron transport in Hibiscus rosa-sinensis is insignificant (< or = 10%). PMID:21195049

  7. 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.

  8. Electronic structure calculations of mercury mobilization from mineral phases and photocatalytic removal from water and the atmosphere

    International Nuclear Information System (INIS)

    Mercury is a hazardous environmental pollutant mobilized from natural sources, and anthropogenically contaminated and disturbed areas. Current methods to assess mobility and environmental impact are mainly based on field measurements, soil monitoring, and kinetic modelling. In order to understand in detail the extent to which different mineral sources can give rise to mercury release it is necessary to investigate the complexity at the microscopic level and the possible degradation/dissolution processes. In this work, we investigated the potential for mobilization of mercury structurally trapped in three relevant minerals occurring in hot spring environments and mining areas, namely, cinnabar (α-HgS), corderoite (α-Hg3S2Cl2), and mercuric chloride (HgCl2). Quantum chemical methods based on density functional theory as well as more sophisticated approaches are used to assess the possibility of a) direct photoreduction and formation of elemental Hg at the surface of the minerals, providing a path for ready release in the environment; and b) reductive dissolution of the minerals in the presence of solutions containing halogens. Furthermore, we study the use of TiO2 as a potential photocatalyst for decontamination of polluted waters (mainly Hg2+-containing species) and air (atmospheric Hg0). Our results partially explain the observed pathways of Hg mobilization from relevant minerals and the microscopic mechanisms behind photocatalytic removal of Hg-based pollutants. Possible sources of disagreement with observations are discussed and further improvements to our approach are suggested. - Highlights: • Mercury mobilization pathways from three Hg bearing minerals were studied. • Their electronic properties were analysed using quantum mechanical modelling. • Cinnabar and corderoite are not photodegradable, but mercuric chloride is. • The trend is reversed for dissolution induced by the presence of halogen couples. • Photocatalytic removal of Hg from air and

  9. Electronic structure calculations of mercury mobilization from mineral phases and photocatalytic removal from water and the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Da Pieve, Fabiana, E-mail: fabiana.dapieve@gmail.com [Université libre de Bruxelles (U.L.B.), Boulevard du Triomphe, CP 231, Campus Plaine, B-1050 Bruxelles (Belgium); Stankowski, Martin [LU Open Innovation Center, Lund University, Box 117, SE-221 00 Lund (Sweden); European Theoretical Spectroscopy Facility (ETSF) (Country Unknown); Hogan, Conor [European Theoretical Spectroscopy Facility (ETSF) (Country Unknown); Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia (CNR–ISM), University of Rome “Tor Vergata”, via Fosso del Cavaliere 100, 00133 Rome (Italy); Physics Department, University of Rome “Tor Vergata”, via Fosso del Cavaliere 100, 00133 Rome (Italy)

    2014-09-15

    Mercury is a hazardous environmental pollutant mobilized from natural sources, and anthropogenically contaminated and disturbed areas. Current methods to assess mobility and environmental impact are mainly based on field measurements, soil monitoring, and kinetic modelling. In order to understand in detail the extent to which different mineral sources can give rise to mercury release it is necessary to investigate the complexity at the microscopic level and the possible degradation/dissolution processes. In this work, we investigated the potential for mobilization of mercury structurally trapped in three relevant minerals occurring in hot spring environments and mining areas, namely, cinnabar (α-HgS), corderoite (α-Hg{sub 3}S{sub 2}Cl{sub 2}), and mercuric chloride (HgCl{sub 2}). Quantum chemical methods based on density functional theory as well as more sophisticated approaches are used to assess the possibility of a) direct photoreduction and formation of elemental Hg at the surface of the minerals, providing a path for ready release in the environment; and b) reductive dissolution of the minerals in the presence of solutions containing halogens. Furthermore, we study the use of TiO{sub 2} as a potential photocatalyst for decontamination of polluted waters (mainly Hg{sup 2+}-containing species) and air (atmospheric Hg{sup 0}). Our results partially explain the observed pathways of Hg mobilization from relevant minerals and the microscopic mechanisms behind photocatalytic removal of Hg-based pollutants. Possible sources of disagreement with observations are discussed and further improvements to our approach are suggested. - Highlights: • Mercury mobilization pathways from three Hg bearing minerals were studied. • Their electronic properties were analysed using quantum mechanical modelling. • Cinnabar and corderoite are not photodegradable, but mercuric chloride is. • The trend is reversed for dissolution induced by the presence of halogen couples.

  10. 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.

  11. 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)

  12. Analysis of inhibition of photosynthesis due to water stress in the C3 species Hordeum vulgare and Vicia faba: Electron transport, CO 2 fixation and carboxylation capacity.

    Science.gov (United States)

    Lal, A; Ku, M S; Edwards, G E

    1996-07-01

    A C3 monocot, Hordeum vulgare and C3 dicot, Vicia faba, were studied to evaluate the mechanism of inhibition of photosynthesis due to water stress. The net rate of CO2 fixation (A) and transpiration (E) were measured by gas exchange, while the true rate of O2 evolution (J O2) was calculated from chlorophyll fluorescence analysis through the stress cycle (10 to 11 days). With the development of water stress, the decrease in A was more pronounced than the decrease in J O2 resulting in an increased ratio of Photosystem II activity per CO2 fixed which is indicative of an increase in photorespiration due to a decrease in supply of CO2 to Rubisco. Analyses of changes in the J O2 A ratios versus that of CO2 limited photosynthesis in well watered plants, and RuBP pool/RuBP binding sites on Rubisco and RuBP activity, indicate a decreased supply of CO2 to Rubisco under both mild and severe stress is primarily responsible for the decrease in CO2 fixation. In the early stages of stress, the decrease in C i (intercellular CO2) due to stomatal closure can account for the decrease in photosynthesis. Under more severe stress, CO2 supply to Rubisco, calculated from analysis of electron flow and CO2 exchange, continued to decrease. However, C i, calculated from analysis of transpiration and CO2 exchange, either remained constant or increased which may be due to either a decrease in mesophyll conductance or an overestimation of C i by this method due to patchiness in conductance of CO2 to the intercellular space. When plants were rewatered after photosynthesis had dropped to 10-30% of the original rate, both species showed near full recovery within two to four days. PMID:24271534

  13. An identical-location transmission electron microscopy study on the degradation of Pt/C nanoparticles under oxidizing, reducing and neutral atmosphere

    International Nuclear Information System (INIS)

    This study shows that the predominant degradation mechanism of Pt/Vulcan XC72 electrocatalysts strongly depends on the nature of the gas atmosphere and of the upper potential limit used in accelerated stress tests (ASTs). The morphological changes of Pt/Vulcan XC72 nanoparticles were studied by identical location transmission electron microscopy (IL-TEM), following accelerated stress tests in different potential ranges and under various gas atmospheres. X-ray photoelectron spectroscopy was used to probe changes in carbon surface chemistry. Whereas minor changes were detected under neutral atmosphere (Ar) and low potential limit conditions (0.05 2). With an increase of the upper potential limit to 1.23 V vs. RHE, the trends observed previously were maintained but 3D Ostwald ripening strongly overlapped with the three other degradation mechanisms, precluding any identification of the dominant mechanism

  14. Evaluation of radiation doses to man due to consumption of milk and leafy vegetables after the accidental atmospheric releases of 131I and 137Cs

    International Nuclear Information System (INIS)

    This paper deals with the evaluation of doses to man due to the consumption of milk and leafy vegetables after accidental environmental releases of 131I, and 137Cs. In this study air to plant transfer factors have been experimentally determined using a specially designed exposure chamber. The experimentally obtained mass interception factors for spinach and fenugreek are 0.18 and 0.14 m2 kg-1 (wet weight basis) respectively. The average yearly consumption of leafy vegetable and milk by an adult Indian is 28 kg and 39 liter as per the UNSCEAR-2000. The large milching animals in India on an average, consume about 8.1 kg/day of dry grass. Washing of these plants, brings down the level of contamination and hence radiation doses to man by 20-30%. The dose received by a member of public by consuming milk and leafy vegetable works out to about 409 and 170 nSv per day with 1 kBq m-2 ground deposition, each of 131I and 137Cs. (author)

  15. 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.

  16. Electron emission due to highly charged ion impact on surfaces: a comparison between a conducting Au(111) and an insulating LiF(001) target

    International Nuclear Information System (INIS)

    Full text: Highly charged ions (HCI) carry a large amount of potential energy and are a promising tool for future nanostructuring efforts. Their interaction with metal surfaces, which leads to the formation of so-called 'hollow atoms', has been studied extensively over the past 15 years and is now well understood. Due to the dielectric response of insulator surfaces (less image charge acceleration, slow hole mobility) results for the interaction of HCI with insulator surfaces are difficult to predict by available theoretical models. We have therefore constructed an experimental setup which allows to investigate electron emission from both a conducting Au(111) and an insulating LiF(001) single-crystal target. As projectile ions we use HCI from the Heidelberg-EBIT, where xenon projectile charge states exceeding 50+ can be reached. The electron emission yields are studied at different impact velocities and ion impact angles. First experiments using xenon ions have already been performed and experiments with argon and uranium ions are planned for this summer. We will present and discuss the results from these experiments. (author)

  17. 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

    International Nuclear Information System (INIS)

    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. (extreme light fields and their applications)

  18. 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.

  19. On the capability of in-situ exposure in an environmental scanning electron microscope for investigating the atmospheric corrosion of magnesium

    International Nuclear Information System (INIS)

    The feasibility of environmental scanning electron microscope (ESEM) in studying the atmospheric corrosion behavior of 99.97% Mg was investigated. For reference, ex-situ exposure was performed. A model system was designed by spraying few salt particles on the metal surface and further promoting the corrosion process using platinum (Pt) deposition in the form of 1×1×1 µm3 dots around the salt particles to create strong artificial cathodic sites. The results showed that the electron beam play a significant role in the corrosion process of scanned regions. This was attributed to the irradiation damage occurring on the metal surface during the ESEM in-situ experiment. After achieving to a reliable process route, in a successful attempt, the morphology and composition of the corrosion products formed in-situ in the ESEM were in agreement with those of the sample exposed ex-situ. - Highlights: • The feasibility of in-situ microscopy and atmospheric corrosion exposures of pure Mg in an ESEM are examined. • A model system was designed using NaCl particles on parts of the metal surface and promoting the corrosion process by depositing 1×1×1 µm3 Pt dots to create strong artificial cathodic sites. • The electron beam used for ESEM imaging affects the in-situ corrosion process. • A proper cleaning procedure for the sample and microscope chamber reducing carbon contamination makes the results from the ESEM in-situ exposures comparable to ex-situ exposures

  20. 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

  1. 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.

  2. 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. PMID:26415103

  3. Suppression of ionization probability due to Rabi oscillations in the resonance two-photon ionization of He by EUV free-electron lasers

    International Nuclear Information System (INIS)

    The two-photon resonance ionization probability of atoms in strong extreme-ultraviolet free-electron laser (EUV FEL) pulses has been investigated by the model of time-dependent wave packet propagation of a light-coupled multilevel atom. Under the simulation within the model assuming single-mode FEL pulses, the ionization probability Pion has shown characteristic dependences on the scaled coupling parameter Ugi between two levels of the ground (g) and intermediate (i) resonance states, namely, Pion∝(Ugi)n, with n being equal to ∼2, less than 1, and ∼1 for the small, medium, and large Ugi regimes, respectively. This power dependence of the ionization probability has been interpreted due to Rabi oscillations between g and i states. To compare with recent experimental results on the same condition, the multimode nature of self-amplitude spontaneous emission (SASE) FEL pulses has been managed in the simulation. Then, the recent experimental laser-power dependence of the two-photon resonance ionization of He [Sato et al., J. Phys. B 44, 161001 (2011)] has been well described by that for the large Ugi regime of the simulation, i.e., n∼ 1. Thus, the observed linear laser-power dependence has been rationalized as being caused by the strong Rabi oscillations between the (2p)-(1s) states.

  4. 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.

  5. RECONSTRUCTION OF EXTERNAL DOSES TO OZYORSK RESIDENTS DUE TO ATMOSPHERIC RELEASES OF INERT RADIOACTIVE GASES FROM THE STACKS OF THE “MAYAK” PA REACTOR PLANT FROM 1948 TO 1989

    Energy Technology Data Exchange (ETDEWEB)

    Glagolenko, Y. V.; Drozhko, Evgeniy G.; Mokrov, Y.; Rovny, Sergey I.; Beregich, D. A.; Stukalov, Pavel M.; Ivanov, I. A.; Alexakhin, A. I.; Anspaugh, L. R.; Napier, Bruce A.

    2008-06-01

    The article provides the results of reconstruction of external doses to population due to atmospheric releases of inert radioactive gases of activation (41Ar) and fission origin (xenon and krypton isotopes) from the stacks of the “Mayak” PA industrial reactors from 1948 to 1989. Calculation of surface volumetric activities was performed using the RATCHET code. Dose estimate was obtained in a semi-infinite cloud approximation. It is demonstrated that more than 90% of external dose was accumulated from 1948 to 1956. It is established that, generally, the calculation results are in good agreement with archive instrument monitoring data on exposure dose rate and thermoluminescence dosimetry data. External effective doses to the residents of Ozyorsk obtained for different age groups of population with consideration of shielding properties of buildings and duration of time spent outdoors were estimated in the range from 16 to 23 mSv.

  6. Electrons

    International Nuclear Information System (INIS)

    Fast electrons are used to produce isotopes for studying the cooper metabolism: Cu-64 in a cyclotron and Cu-67 in a linear accelerator. Localized electrons are responsible for the chemical and physiological characteristics of the trace elements. Studied are I, Cu, Co, Zn, Mo, Mn, Fe, Se, Mg. The Cu/Mo and Cu/Zn interactions are investigated. The levels of molybdenum, sulfate and zinc in the food are analysed. The role of the electrons in free radicals is discussed. The protection action of peroxidases and super oxidases against electron dangerous effect on normal physiology is also considered. Calculation of radiation damage and radiation protection is made. (author)

  7. Ultrastructural Analysis of Nanogold-Labeled Cell Surface Microvilli in Liquid by Atmospheric Scanning Electron Microscopy and Their Relevance in Cell Adhesion

    Directory of Open Access Journals (Sweden)

    Mitsuo Suga

    2013-10-01

    Full Text Available The adhesion of leukocytes circulating in the blood to vascular endothelium is critical for their trafficking in the vasculature, and CD44 is an important cell surface receptor for rolling adhesion. In this study, we demonstrate the correlative observation of CD44 distribution at the lymphocyte cell surface in liquid by fluorescence optical microscopy and immuno-electron microscopy using an atmospheric scanning electron microscope (ASEM. The ultrastructure of the cell surface was clearly imaged by ASEM using positively charged Nanogold particles. ASEM analysis demonstrated microvilli projections around the cell surface and the localization of CD44 on the microvilli. Treatment of cells with cytochalasin D resulted in a loss of the microvilli projections and concomitantly abrogated CD44-mediated adhesion to its ligand hyaluronan. These results suggest the functional relevance of microvilli in CD44-mediated rolling adhesion under shear flow.

  8. On the capability of in-situ exposure in an environmental scanning electron microscope for investigating the atmospheric corrosion of magnesium.

    Science.gov (United States)

    Esmaily, M; Mortazavi, N; Shahabi-Navid, M; Svensson, J E; Johansson, L G; Halvarsson, M

    2015-06-01

    The feasibility of environmental scanning electron microscope (ESEM) in studying the atmospheric corrosion behavior of 99.97% Mg was investigated. For reference, ex-situ exposure was performed. A model system was designed by spraying few salt particles on the metal surface and further promoting the corrosion process using platinum (Pt) deposition in the form of 1×1×1 µm(3) dots around the salt particles to create strong artificial cathodic sites. The results showed that the electron beam play a significant role in the corrosion process of scanned regions. This was attributed to the irradiation damage occurring on the metal surface during the ESEM in-situ experiment. After achieving to a reliable process route, in a successful attempt, the morphology and composition of the corrosion products formed in-situ in the ESEM were in agreement with those of the sample exposed ex-situ. PMID:25731810

  9. 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

  10. Generation of 'Super-Ponderomotive' Electrons due to a non-Wakefield interaction between a Laser Pulse and a Longitudinal Electric Field

    CERN Document Server

    Robinson, A P L; Neely, D

    2013-01-01

    It is shown that electrons with momenta exceeding the `free electron' limit of $m_eca_0^2/2$ can be produced when a laser pulse and a longitudinal electric field interact with an electron via a non-wakefield mechanism. The mechanism consists of two stages: the reduction of the electron dephasing rate $\\gamma-p_x/m_ec$ by an accelerating region of electric field and electron acceleration by the laser via the Lorentz force. This mechanism can, in principle, produce electrons that have longtudinal momenta that is a significant multiple of $m_eca_0^2/2$. 2D PIC simulations of a relatively simple laser-plasma interaction indicate that the generation of super-ponderomotive electrons is strongly affected by this `anti-dephasing' mechanism.

  11. Correction for ‘artificial’ electron disequilibrium due to cone-beam CT density errors: implications for on-line adaptive stereotactic body radiation therapy of lung

    Science.gov (United States)

    Disher, Brandon; Hajdok, George; Wang, An; Craig, Jeff; Gaede, Stewart; Battista, Jerry J.

    2013-06-01

    Cone-beam computed tomography (CBCT) has rapidly become a clinically useful imaging modality for image-guided radiation therapy. Unfortunately, CBCT images of the thorax are susceptible to artefacts due to scattered photons, beam hardening, lag in data acquisition, and respiratory motion during a slow scan. These limitations cause dose errors when CBCT image data are used directly in dose computations for on-line, dose adaptive radiation therapy (DART). The purpose of this work is to assess the magnitude of errors in CBCT numbers (HU), and determine the resultant effects on derived tissue density and computed dose accuracy for stereotactic body radiation therapy (SBRT) of lung cancer. Planning CT (PCT) images of three lung patients were acquired using a Philips multi-slice helical CT simulator, while CBCT images were obtained with a Varian On-Board Imaging system. To account for erroneous CBCT data, three practical correction techniques were tested: (1) conversion of CBCT numbers to electron density using phantoms, (2) replacement of individual CBCT pixel values with bulk CT numbers, averaged from PCT images for tissue regions, and (3) limited replacement of CBCT lung pixels values (LCT) likely to produce artificial lateral electron disequilibrium. For each corrected CBCT data set, lung SBRT dose distributions were computed for a 6 MV volume modulated arc therapy (VMAT) technique within the Philips Pinnacle treatment planning system. The reference prescription dose was set such that 95% of the planning target volume (PTV) received at least 54 Gy (i.e. D95). Further, we used the relative depth dose factor as an a priori index to predict the effects of incorrect low tissue density on computed lung dose in regions of severe electron disequilibrium. CT number profiles from co-registered CBCT and PCT patient lung images revealed many reduced lung pixel values in CBCT data, with some pixels corresponding to vacuum (-1000 HU). Similarly, CBCT data in a plastic lung

  12. Correction for 'artificial' electron disequilibrium due to cone-beam CT density errors: implications for on-line adaptive stereotactic body radiation therapy of lung.

    Science.gov (United States)

    Disher, Brandon; Hajdok, George; Wang, An; Craig, Jeff; Gaede, Stewart; Battista, Jerry J

    2013-06-21

    Cone-beam computed tomography (CBCT) has rapidly become a clinically useful imaging modality for image-guided radiation therapy. Unfortunately, CBCT images of the thorax are susceptible to artefacts due to scattered photons, beam hardening, lag in data acquisition, and respiratory motion during a slow scan. These limitations cause dose errors when CBCT image data are used directly in dose computations for on-line, dose adaptive radiation therapy (DART). The purpose of this work is to assess the magnitude of errors in CBCT numbers (HU), and determine the resultant effects on derived tissue density and computed dose accuracy for stereotactic body radiation therapy (SBRT) of lung cancer. Planning CT (PCT) images of three lung patients were acquired using a Philips multi-slice helical CT simulator, while CBCT images were obtained with a Varian On-Board Imaging system. To account for erroneous CBCT data, three practical correction techniques were tested: (1) conversion of CBCT numbers to electron density using phantoms, (2) replacement of individual CBCT pixel values with bulk CT numbers, averaged from PCT images for tissue regions, and (3) limited replacement of CBCT lung pixels values (LCT) likely to produce artificial lateral electron disequilibrium. For each corrected CBCT data set, lung SBRT dose distributions were computed for a 6 MV volume modulated arc therapy (VMAT) technique within the Philips Pinnacle treatment planning system. The reference prescription dose was set such that 95% of the planning target volume (PTV) received at least 54 Gy (i.e. D95). Further, we used the relative depth dose factor as an a priori index to predict the effects of incorrect low tissue density on computed lung dose in regions of severe electron disequilibrium. CT number profiles from co-registered CBCT and PCT patient lung images revealed many reduced lung pixel values in CBCT data, with some pixels corresponding to vacuum (-1000 HU). Similarly, CBCT data in a plastic lung

  13. Correction for ‘artificial’ electron disequilibrium due to cone-beam CT density errors: implications for on-line adaptive stereotactic body radiation therapy of lung

    International Nuclear Information System (INIS)

    Cone-beam computed tomography (CBCT) has rapidly become a clinically useful imaging modality for image-guided radiation therapy. Unfortunately, CBCT images of the thorax are susceptible to artefacts due to scattered photons, beam hardening, lag in data acquisition, and respiratory motion during a slow scan. These limitations cause dose errors when CBCT image data are used directly in dose computations for on-line, dose adaptive radiation therapy (DART). The purpose of this work is to assess the magnitude of errors in CBCT numbers (HU), and determine the resultant effects on derived tissue density and computed dose accuracy for stereotactic body radiation therapy (SBRT) of lung cancer. Planning CT (PCT) images of three lung patients were acquired using a Philips multi-slice helical CT simulator, while CBCT images were obtained with a Varian On-Board Imaging system. To account for erroneous CBCT data, three practical correction techniques were tested: (1) conversion of CBCT numbers to electron density using phantoms, (2) replacement of individual CBCT pixel values with bulk CT numbers, averaged from PCT images for tissue regions, and (3) limited replacement of CBCT lung pixels values (LCT) likely to produce artificial lateral electron disequilibrium. For each corrected CBCT data set, lung SBRT dose distributions were computed for a 6 MV volume modulated arc therapy (VMAT) technique within the Philips Pinnacle treatment planning system. The reference prescription dose was set such that 95% of the planning target volume (PTV) received at least 54 Gy (i.e. D95). Further, we used the relative depth dose factor as an a priori index to predict the effects of incorrect low tissue density on computed lung dose in regions of severe electron disequilibrium. CT number profiles from co-registered CBCT and PCT patient lung images revealed many reduced lung pixel values in CBCT data, with some pixels corresponding to vacuum (−1000 HU). Similarly, CBCT data in a plastic lung

  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. Due diligence

    International Nuclear Information System (INIS)

    The Occupational Health and Safety (OHS) Act requires that every employer shall ensure the health and safety of workers in the workplace. Issues regarding the practices at workplaces and how they should reflect the standards of due diligence were discussed. Due diligence was described as being the need for employers to identify hazards in the workplace and to take active steps to prevent workers from potentially dangerous incidents. The paper discussed various aspects of due diligence including policy, training, procedures, measurement and enforcement. The consequences of contravening the OHS Act were also described

  16. Transmission electron microscopy on early-stage tin oxide film morphology grown by atmospheric pressure chemical vapor deposition

    International Nuclear Information System (INIS)

    Nucleation and morphology development during the early stages of chemical vapor deposition (CVD) processes are believed to be of major importance for the overall film properties. Here, the authors have investigated the nucleation of tin oxide films, comparing different tin precursors (tin tetrachloride (TTC) and monobutyl tin trichloride (MBTC)) and focusing on the effect of methanol addition on the film morphology. Employing electron transparent silicon oxide membranes as substrates and combining transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis on the same set of samples, we describe a detailed picture of nucleation behavior and film growth during early stages of film formation. Our main conclusion is that methanol addition during deposition acts as surfactant, lowering the surface energy of the substrate and resulting in a higher nucleation grain density. Based on these results, we propose a film growth model based on surface energy to explain morphology differences in tin oxide films resulting from methanol addition.

  17. 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.

  18. On the capability of in-situ exposure in an environmental scanning electron microscope for investigating the atmospheric corrosion of magnesium

    Energy Technology Data Exchange (ETDEWEB)

    Esmaily, M., E-mail: mohsen.esmaily@chalmers.se [Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Mortazavi, N. [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Shahabi-Navid, M.; Svensson, J.E.; Johansson, L.G. [Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Halvarsson, M. [Department of Applied Physics, Chalmers University of Technology, SE-412 96 Gothenburg (Sweden)

    2015-06-15

    The feasibility of environmental scanning electron microscope (ESEM) in studying the atmospheric corrosion behavior of 99.97% Mg was investigated. For reference, ex-situ exposure was performed. A model system was designed by spraying few salt particles on the metal surface and further promoting the corrosion process using platinum (Pt) deposition in the form of 1×1×1 µm{sup 3} dots around the salt particles to create strong artificial cathodic sites. The results showed that the electron beam play a significant role in the corrosion process of scanned regions. This was attributed to the irradiation damage occurring on the metal surface during the ESEM in-situ experiment. After achieving to a reliable process route, in a successful attempt, the morphology and composition of the corrosion products formed in-situ in the ESEM were in agreement with those of the sample exposed ex-situ. - Highlights: • The feasibility of in-situ microscopy and atmospheric corrosion exposures of pure Mg in an ESEM are examined. • A model system was designed using NaCl particles on parts of the metal surface and promoting the corrosion process by depositing 1×1×1 µm{sup 3} Pt dots to create strong artificial cathodic sites. • The electron beam used for ESEM imaging affects the in-situ corrosion process. • A proper cleaning procedure for the sample and microscope chamber reducing carbon contamination makes the results from the ESEM in-situ exposures comparable to ex-situ exposures.

  19. A novel method to determine the electron temperature and density from the absolute intensity of line and continuum emission: application to atmospheric microwave induced Ar plasmas

    International Nuclear Information System (INIS)

    An absolute intensity measurement (AIM) technique is presented that combines the absolute measurements of the line and the continuum emitted by strongly ionizing argon plasmas. AIM is an iterative combination of the absolute line intensity-collisional radiative model (ALI-CRM) and the absolute continuum intensity (ACI) method. The basis of ALI-CRM is that the excitation temperature T13 determined by the method of ALI is transformed into the electron temperature Te using a CRM. This gives Te as a weak function of electron density ne. The ACI method is based on the absolute value of the continuum radiation and determines the electron density in a way that depends on Te. The iterative combination gives ne and Te. As a case study the AIM method is applied to plasmas created by torche a injection axiale (TIA) at atmospheric pressure and fixed frequency at 2.45 GHz. The standard operating settings are a gas flow of 1 slm and a power of 800 W; the measurements have been performed at a position of 1 mm above the nozzle. With AIM we found an electron temperature of 1.2 eV and electron density values around 1021 m-3. There is not much dependence of these values on the plasma control parameters (power and gas flow). From the error analysis we can conclude that the determination of Te is within 7% and thus rather accurate but comparison with other studies shows strong deviations. The ne determination comes with an error of 40% but is in reasonable agreement with other experimental results.

  20. Electronics

    International Nuclear Information System (INIS)

    Some of the electronic equipment used in pulse counting and mean current radiation detection systems is described. This includes the high voltage supply, amplifier, amplitude discriminator, scalers or counters, ratemeters, single-channel pulse height analyser, multi-channel pulse height analyser, d.c. amplifiers, coincidence and anticoincidence units and gain stabilisers

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

    International Nuclear Information System (INIS)

    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 D10 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 2oC of meat samples irradiated at 0.5 kGy further reduced the number of A. hydrophila. (Author)

  2. Electronic structure calculations of mercury mobilization from mineral phases and photocatalytic removal from water and the atmosphere.

    Science.gov (United States)

    Da Pieve, Fabiana; Stankowski, Martin; Hogan, Conor

    2014-09-15

    Mercury is a hazardous environmental pollutant mobilized from natural sources, and anthropogenically contaminated and disturbed areas. Current methods to assess mobility and environmental impact are mainly based on field measurements, soil monitoring, and kinetic modelling. In order to understand in detail the extent to which different mineral sources can give rise to mercury release it is necessary to investigate the complexity at the microscopic level and the possible degradation/dissolution processes. In this work, we investigated the potential for mobilization of mercury structurally trapped in three relevant minerals occurring in hot spring environments and mining areas, namely, cinnabar (α-HgS), corderoite (α-Hg3S2Cl2), and mercuric chloride (HgCl2). Quantum chemical methods based on density functional theory as well as more sophisticated approaches are used to assess the possibility of a) direct photoreduction and formation of elemental Hg at the surface of the minerals, providing a path for ready release in the environment; and b) reductive dissolution of the minerals in the presence of solutions containing halogens. Furthermore, we study the use of TiO2 as a potential photocatalyst for decontamination of polluted waters (mainly Hg(2+)-containing species) and air (atmospheric Hg(0)). Our results partially explain the observed pathways of Hg mobilization from relevant minerals and the microscopic mechanisms behind photocatalytic removal of Hg-based pollutants. Possible sources of disagreement with observations are discussed and further improvements to our approach are suggested. PMID:24982025

  3. The electronic Space Weather upper atmosphere (eSWua project at INGV: advancements and state of the art

    Directory of Open Access Journals (Sweden)

    V. Romano

    2008-02-01

    Full Text Available The eSWua project is based on measurements performed by all the instruments installed by the upper atmosphere physics group of the Istituto Nazionale di Geofisica e Vulcanologia, Italy and on all the related studies. The aim is the realization of a hardware-software system to standardize historical and real-time observations for different instruments.

    An interactive Web site, supported by a well organized database, can be a powerful tool for the scientific and technological community in the field of telecommunications and space weather. The most common and useful database type for our purposes is the relational one, in which data are organized in tables for petabytes data archiving and the complete flexibility in data retrieving.

    The project started in June 2005 and will last till August 2007. In the first phase the major effort has been focused on the design of hardware and database architecture. The first two databases related to the DPS4 digisonde and GISTM measurements are complete concerning populating, tests and output procedures. Details on the structure and Web tools concerning these two databases are presented, as well as the general description of the project and technical features.

  4. Oxidation of metals and alloys in controlled atmospheres using in situ transmission electron microscopy and Auger spectrography

    Science.gov (United States)

    Rao, D. B.; Heinemann, K.; Douglass, D. L.

    1976-01-01

    Single-crystalline thin films of copper were oxidized at an isothermal temperature of 425 C and at an oxygen partial pressure of .005 Torr in situ in a high-resolution electron microscope. The specimens were prepared by epitaxial vapor deposition onto polished 100 and 110 faces of rocksalt and mounted in a hot stage inside an ultra-high-vacuum specimen chamber of the microscope. Large amounts of sulfur, carbon, and oxygen were detected by Auger electron spectroscopy on the surface of the as-received films and were removed in situ by ion-sputter etching immediately prior to the oxidation. The nucleation and growth characteristics of Cu2O on Cu were studied. Results show that neither stacking faults nor dislocations are associated with the Cu2O nucleation sites. The growth of Cu2O nuclei is linear with time. The experimental findings, including results from oxygen dissolution experiments and from repetitive oxidation-reduction-oxidation sequences, fit well into the framework of an oxidation process involving (a) the formation of a surface-charge layer, (b) oxygen saturation in the metal and (c) nucleation, followed by surface diffusion of oxygen and bulk diffusion of copper for lateral and vertical oxide growth, respectively.

  5. HARD X-RAY FOOTPOINT SIZES AND POSITIONS AS DIAGNOSTICS OF FLARE ACCELERATED ENERGETIC ELECTRONS IN THE LOW SOLAR ATMOSPHERE

    International Nuclear Information System (INIS)

    The hard X-ray (HXR) emission in solar flares comes almost exclusively from a very small part of the flaring region, the footpoints of magnetic loops. Using RHESSI observations of solar flare footpoints, we determine the radial positions and sizes of footpoints as a function of energy in six near-limb events to investigate the transport of flare accelerated electrons and the properties of the chromosphere. HXR visibility forward fitting allows us to find the positions/heights and the sizes of HXR footpoints along and perpendicular to the magnetic field of the flaring loop at different energies in the HXR range. We show that in half of the analyzed events, a clear trend of decreasing height of the sources with energy is found. Assuming collisional thick-target transport, HXR sources are located between 600 and 1200 km above the photosphere for photon energies between 120 and 25 keV, respectively. In the other events, the position as a function of energy is constant within the uncertainties. The vertical sizes (along the path of electron propagation) range from 1.3 to 8 arcsec which is up to a factor four larger than predicted by the thick-target model even in events where the positions/heights of HXR sources are consistent with the collisional thick-target model. Magnetic mirroring, collisional pitch-angle scattering, and X-ray albedo are discussed as potential explanations of the findings.

  6. A model for track formation due to electronic slowing down of swift heavy ions in metallic materials. Experimental survey in bismuth

    International Nuclear Information System (INIS)

    A charged particle passing through solid matter undergoes elastic collisions with the target nuclei and inelastic collisions with the target electrons. All these collisions result in defect creation along the ion path. The disordered matter is called the ion track. The elastic collision process is now experimentally and theoretically well known. The inelastic process is the main source of stopping power of swift heavy ions in matter. In which way can the energy deposited on the target electrons lead to defect creation in the atomic lattice. The present work deals with that question with the aid of the thermal spike model. The target is composed of two interacting systems: the electrons and the atomic lattice characterized by their thermodynamical properties (specific heat and thermal diffusivity). The energy deposited by the ion expands itself within the electron gas and is transferred to the atomic lattice by electron-phonon interaction. As a consequence of this energy transfer, the lattice temperature increases and may induce a local fusion of the matter which is then quenched by thermal contact with the surrounding medium. A cylindrical track is supposed to be created. A numerical calculation of the electronic and atomic temperatures. A track radius is determined. An experimental survey has been made in bismuth in order to study the radiation effects by swift heavy ions (O, Mg, Kr, Xe, Ta, Pb, U). We made the analysis of the evolution of the resistivity increment as a function of the number of ions per surface unit. Latent track radii were deduced and compared to calculated ones in the fields of the thermal spike model. (author). refs., figs., tabs

  7. Variations of the electron density in the low and middle latitude ionosphere due to high-speed solar wind streams observed by the DEMETER satellite

    Science.gov (United States)

    Kim, H. E.; Lee, E.; Kim, K. H.; Lee, D. H.; Ryu, K.; Chae, J.; Parrot, M.

    2014-12-01

    Earth's ionosphere varies very dynamically according to the geomagnetic activities and solar irradiance. Recently it has been studied that the plasma and neutral densities in the thermosphere and ionosphere show periodic oscillations with respect to the solar wind speed and Kp index during the declining phase of the solar cycle. In this study, we investigate the relationship between the electron density and the solar wind speed during the declining phase of the solar cycle using the observation from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite at the altitude of 660 km. The electron density near the dip equator tends to increase with the solar wind speed from January to April, but there is no clear tendency in the other times. Also, the electron density shows good relationship with the solar wind speed at the magnetic longitudes from 240 to 300 degrees. However, there is poor relationship in the other longitudes. We will discuss the seasonal and longitudinal dependences of the electron density on the solar wind speed in the low and middle latitude ionosphere.

  8. Total electron emission from metals due to the impact of highly-charged Xe ioms with energies up to MeV

    Czech Academy of Sciences Publication Activity Database

    Láska, Leoš; Krása, Josef; Stöckli, M. P.; Fehrenbach, C. W.

    2001-01-01

    Roč. 51, č. 8 (2001), s. 791-797. ISSN 0011-4626 R&D Projects: GA AV ČR IAA1010819 Institutional research plan: CEZ:AV0Z1010921 Keywords : corpuscular diagnostic * multiply charged ions * secondary electron emission Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.345, year: 2001

  9. Recovery effects due to the interaction between nuclear and electronic energy losses in SiC irradiated with a dual-ion beam

    Science.gov (United States)

    Thomé, Lionel; Velisa, Gihan; Miro, Sandrine; Debelle, Aurélien; Garrido, Frédérico; Sattonnay, Gaël; Mylonas, Stamatis; Trocellier, Patrick; Serruys, Yves

    2015-03-01

    Single and dual-beam ion irradiations of silicon carbide (SiC) were performed to study possible Synergetic effects between Nuclear (Sn) and Electronic (Se) Energy Losses. Results obtained combining Rutherford backscattering in channeling conditions, Raman spectroscopy, and transmission electron microscopy techniques show that dual-beam irradiation of SiC induces a dramatic change in the final sample microstructure with a substantial decrease of radiation damage as compared to single-beam irradiation. Actually, a defective layer containing dislocations is formed upon dual-beam irradiation (Sn&Se), whereas single low-energy irradiation (Sn alone) or even sequential (Sn + Se) irradiations lead to full amorphization. The healing process is ascribed to the electronic excitation arising from the electronic energy loss of swift ions. These results shed new light on the long-standing puzzling problem of the existence of a possible synergy between Sn and Se in ion-irradiation experiments. This work is interesting for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where recovery Sn/Se effects may preserve the integrity of nuclear devices.

  10. Recovery effects due to the interaction between nuclear and electronic energy losses in SiC irradiated with a dual-ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Thomé, Lionel, E-mail: thome@csnsm.in2p3.fr; Debelle, Aurélien; Garrido, Frédérico; Sattonnay, Gaël; Mylonas, Stamatis [Centre de Sciences Nucléaires et de Sciences de la Matière, CNRS-IN2P3-Université Paris-Sud, Bât. 108, F-91405 Orsay (France); Velisa, Gihan [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O.B. MG-6, 077125 Magurele (Romania); Miro, Sandrine; Trocellier, Patrick; Serruys, Yves [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France)

    2015-03-14

    Single and dual-beam ion irradiations of silicon carbide (SiC) were performed to study possible Synergetic effects between Nuclear (S{sub n}) and Electronic (S{sub e}) Energy Losses. Results obtained combining Rutherford backscattering in channeling conditions, Raman spectroscopy, and transmission electron microscopy techniques show that dual-beam irradiation of SiC induces a dramatic change in the final sample microstructure with a substantial decrease of radiation damage as compared to single-beam irradiation. Actually, a defective layer containing dislocations is formed upon dual-beam irradiation (S{sub n} and S{sub e}), whereas single low-energy irradiation (S{sub n} alone) or even sequential (S{sub n} + S{sub e}) irradiations lead to full amorphization. The healing process is ascribed to the electronic excitation arising from the electronic energy loss of swift ions. These results shed new light on the long-standing puzzling problem of the existence of a possible synergy between S{sub n} and S{sub e} in ion-irradiation experiments. This work is interesting for both fundamental understanding of the ion-solid interactions and technological applications in the nuclear industry where recovery S{sub n}/S{sub e} effects may preserve the integrity of nuclear devices.

  11. 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

    2014-01-01

    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

  12. The temperature dependence of the band gap shrinkage due to the electron-phonon interaction in Al{sub x}Ga{sub 1-x}As

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Niladri; Ghosh, Subhasis [School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067 (India)

    2006-02-08

    The photoluminescence spectrum of band edge transitions in Al{sub x}Ga{sub 1-x}As is studied as a function of temperature and electron concentration. The parameters that describe the temperature dependence redshift of the band edge transition energy are evaluated using different models. We find that a semi-empirical relation based on a phonon dispersion related spectral function leads to an excellent fit to the experimental data.

  13. Infrared rovibrational spectroscopy of OH–C{sub 2}H{sub 2} in {sup 4}He nanodroplets: Parity splitting due to partially quenched electronic angular momentum

    Energy Technology Data Exchange (ETDEWEB)

    Douberly, Gary E., E-mail: douberly@uga.edu; Liang, Tao [Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556 (United States); Raston, Paul L. [Department of Chemistry, University of Adelaide, Adelaide, South Australia 5005 (Australia); Marshall, Mark D., E-mail: mdmarshall@amherst.edu [Department of Chemistry, Amherst College, Amherst, Massachusetts 01002-5000 (United States)

    2015-04-07

    The T-shaped OH–C{sub 2}H{sub 2} complex is formed in helium droplets via the sequential pick-up and solvation of the monomer fragments. Rovibrational spectra of the a-type OH stretch and b-type antisymmetric CH stretch vibrations contain resolved parity splitting that reveals the extent to which electronic angular momentum of the OH moiety is quenched upon complex formation. The energy difference between the spin-orbit coupled {sup 2}B{sub 1} (A″) and {sup 2}B{sub 2} (A′) electronic states is determined spectroscopically to be 216 cm{sup −1} in helium droplets, which is 13 cm{sup −1} larger than in the gas phase [Marshall et al., J. Chem. Phys. 121, 5845 (2004)]. The effect of the helium is rationalized as a difference in the solvation free energies of the two electronic states. This interpretation is motivated by the separation between the Q(3/2) and R(3/2) transitions in the infrared spectrum of the helium-solvated {sup 2}Π{sub 3/2} OH radical. Despite the expectation of a reduced rotational constant, the observed Q(3/2) to R(3/2) splitting is larger than in the gas phase by ≈0.3 cm{sup −1}. This observation can be accounted for quantitatively by assuming the energetic separation between {sup 2}Π{sub 3/2} and {sup 2}Π{sub 1/2} manifolds is increased by ≈40 cm{sup −1} upon helium solvation.

  14. 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; Pejtersen, K.

    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...... 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...

  15. Evaluation of Detrimental Effects on Mechanical Properties of Zry-4 Due to Hydrogen Absorption by means of Scanning Electron Microscopy (SEM) In-Situ Observation of Crack Propagation

    International Nuclear Information System (INIS)

    The study of mechanical properties degradation of zirconium alloys due to hydrides assumes fundamental importance in the nuclear industry.During normal nuclear reactors operation, structural parts absorbed hydrogen generated from radiolysis of water, causing detrimental effects on mechanical properties.As a consequence, these materials are easily cracked in the presence of mechanical solicitation due to loss of ductility of the hydride-phase.The presence of cracks indicates fracture mechanic as the most suitable methodology in the study of mechanical properties degradation.In this work we used the crack tip opening displacement (CTOD) criteria to evaluate the detrimental effects on mechanical properties with the observation in SEM of crack propagation.The samples used were SEN (B) of Zry-4 and cathodic homogenous charged with hydrogen concentrations lower than 400 ppm

  16. Tc amplification in pnictides due to Feshbach shape resonance in multigap superconductivity realized by tuning the Fermi level at the electronic topological transiton to one of the subbands

    Science.gov (United States)

    Bianconi, Antonio; Innocenti, Davide; Poccia, Nicola; Ricci, Alessandro

    2010-03-01

    The new high Tc superconducting Pnictides AFe2As2 (A=Ba,Sr or Ca) are heterostructures at atomic limit like cuprates as described in the patent [A. Bianconi ``Process of increasing the critical temperature Tc of a bulk superconductor by making metal heterostructures at the atomic limit'' United State Patent No. :US6, 265, 019 B1, July 24, 2001] in fact are made of superconducting layers intercalated by spacer layers. ( R. Caivano, et al., Superconductor Science and Technology 22, 014004+ (2009), A. Ricci et al. Journal of Superconductivity and Novel Magnetism 22, 589 (2009)) where the Fermi level is tuned to a electronic topological transition in one of the subbands by doping, pressure or substitutions. Here we present the calculation of the Tc amplification by shape resonance or Feshbach resonance in a superlattice of layers in a narrow range where the chemical potential is tuned to the electronic topological transition as measured recently by NMR (H. Shishido et al. arXiv:0910.3634v1). The computer code tested now in the diborides and pnicitdes can be used for material design of new high Tc superconductors.

  17. Changes of the Electrical and Optical Character of Polyimide Films Due to Exposure to High Energy GEO-like Electrons and the Chemistry that Drives it

    Science.gov (United States)

    Hoffmann, R.; Cooper, R.; Ferguson, D.

    As a result of the interaction between the spacecraft and its operational environment, the constituent materials begin to change. These changes are determined by a combination of: chemical reactions, contamination, and energy deposition. They can range in severity from negligible to total loss of the material. Virtually all properties of the material, the mechanical, optical/thermal, and electrical are altered in largely unknown ways from the pristine materials. This negatively impacts the ability of spacecraft operators to predict the behavior of a spacecraft as it ages its environment. For example, in the case of electrical conduction in polyimide, there is a three orders of magnitude decrease in the resistivity after only eight months of simulated GEO electron exposure. Optical changes in the material also dramatically impact the ability of ground based optical observations to identify and track both known and unknown spacecraft. We will be presenting work done within the Spacecraft Charging and Instrument Calibration Lab at AFRL/RVB to quantify the changes in total reflection, BRDF, and electrical conduction of aluminized polyimide film after simulated aging in a GEO-like electron environment. We correlate these data with the chemical structure of the film as determined by XPS and NMR. A deeper, predictive understanding of how materials change will not only increase the operational lifetime of space assets by providing more accurate data to operators, it will improve SSA by allowing ground based observers to more accurately deduce component materials and determine how long a spacecraft has been in orbit.

  18. 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)

    International Nuclear Information System (INIS)

    This study investigated the biological adaptation of loblolly pine following long-term seasonal exposure to elevated carbon dioxide (CO2) partial pressures (pCO2). Exposure to elevated atmospheric CO2 (pCO2) usually results in significant stimulation in light-saturated rates of photosynthetic CO2 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 pCO2 at the Duke FACE site. The effect of elevated pCO2 on electron transport and energy dissipation in the pine trees was examined by coupling the analyses of the capacity for photosynthetic oxygen (O2) evolution, chlorophyll fluorescence emission and photosynthetic pigment composition with measurements of net photosynthetic CO2 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 pCO2 in comparison with needles of the same age cohort in ambient pCO2. Thus, older needles exhibited greater photosynthetic down-regulation than younger needles in elevated pCO2. In the winter, Asat was not significantly affected by growth pCO2. Asat was lower in winter than in summer. Growth at elevated pCO2 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 pCO2 on Calvin cycle activity. 73 refs., 4 figs

  19. Alpha power effects on energy confinement time and ignition, and enhancement of ion neoclassical heat conduction due to electron and superthermal ion energy scattering collisions

    International Nuclear Information System (INIS)

    In Part A of the paper a purely theoretical model is adopted for the local heat diffusivities χe and χi. The global τE is constructed after Callen et al. and is used in a zero dimensional ignition power balance to study alpha power and fast alpha loss effects on ignition. The Horton-Choi-Yushmanov-Parail model for χe permits ignition in a CIT-like tokamak with B = 13.5 T, Ip = 18 MA, if the fast alpha losses and the ηi mode can be controlled. Part B considers the extra components of neoclassical ion heat conduction driven by energy scattering collisions with electrons and superthermal ions. These components are important in auxiliary heated discharges and can be the most important if the plasma ion distribution has an enhanced non-Maxwellian tail. (author). 19 refs, 4 figs, 1 tab

  20. Enhancement of electron correlation due to the molecular dimerization in organic superconductors β -(BDA-TTP )2X (X =I3, SbF6)

    Science.gov (United States)

    Aizawa, Hirohito; Kuroki, Kazuhiko; Yamada, Jun-ichi

    2015-10-01

    We perform a first-principles band calculation for quasi-two-dimensional organic superconductors β -(BDA -TTP) 2I3 and β -(BDA -TTP) 2SbF6. The first-principles band structures between the I3 and SbF6 salts are apparently different. We construct a tight-binding model for each material which accurately reproduces the first-principles band structure. The obtained transfer energies give the differences as follows: (i) larger dimerization in the I3 salt than the SbF6 salt, and (ii) different signs and directions of the interstacking transfer energies. To decompose the origin of the difference into the dimerization and the interstacking transfer energies, we adopt a simplified model by eliminating the dimerization effect and focus only on the difference caused by the interstacking transfer energies. From the analysis using the simplified model, we find that the difference of the band structure comes mainly from the strength of the dimerization. To compare the strength of the electron correlation having roots in the band structure, we calculate the physical properties originating from the effect of the electron correlation such as the spin susceptibility applying the two-particle self-consistent method. We find that the maximum value of the spin susceptibility for the I3 salt is larger than that of the SbF6 salt. Hypothetically decreasing the dimerization within the model of the I3 salt, the spin susceptibility takes almost the same value as that of the SbF6 salt for the same magnitude of the dimerization. We expect that the different ground state between the I3 and SbF6 salt mainly comes from the strength of the dimerization which is apparently masked in the band calculation along a particular k path.

  1. 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.

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

    International Nuclear Information System (INIS)

    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 H2O 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.

  3. Impact of OH Radical-Initiated H2CO3 Degradation in the Earth's Atmosphere via Proton-Coupled Electron Transfer Mechanism.

    Science.gov (United States)

    Ghoshal, Sourav; Hazra, Montu K

    2016-02-01

    The decomposition of isolated carbonic acid (H2CO3) molecule into CO2 and H2O (H2CO3 → CO2 + H2O) is prevented by a large activation barrier (>35 kcal/mol). Nevertheless, it is surprising that the detection of the H2CO3 molecule has not been possible yet, and the hunt for the free H2CO3 molecule has become challenging not only in the Earth's atmosphere but also on Mars. In view of this fact, we report here the high levels of quantum chemistry calculations investigating both the energetics and kinetics of the OH radical-initiated H2CO3 degradation reaction to interpret the loss of the H2CO3 molecule in the Earth's atmosphere. It is seen from our study that proton-coupled electron transfer (PCET) and hydrogen atom transfer (HAT) are the two mechanisms by which the OH radical initiates the degradation of the H2CO3 molecule. Moreover, the PCET mechanism is potentially the important one, as the effective barrier, defined as the difference between the zero point vibrational energy (ZPE) corrected energy of the transition state and the total energy of the isolated starting reactants in terms of bimolecular encounters, for the PCET mechanism at the CCSD(T)/6-311++G(3df,3pd) level of theory is ∼3 to 4 kcal/mol lower than the effective barrier height associated with the HAT mechanism. The CCSD(T)/6-311++G(3df,3pd) level predicted effective barrier heights for the degradations of the two most stable conformers of H2CO3 molecule via the PCET mechanism are only ∼2.7 and 4.3 kcal/mol. A comparative reaction rate analysis at the CCSD(T)/6-311++G(3df,3pd) level of theory has also been carried out to explore the potential impact of the OH radical-initiated H2CO3 degradation relative to that from water (H2O), formic acid (FA), acetic acid (AA) and sulfuric acid (SA) assisted H2CO3 → CO2 + H2O decomposition reactions in both the Earth's troposphere and stratosphere. The comparison of the reaction rates reveals that, although the atmospheric concentration of the OH radical is

  4. Energy sources of the high latitude upper atmosphere

    Science.gov (United States)

    Banks, P. M.

    1981-01-01

    Electrodynamic (Joule) dissipation and plasma wave heating are reviewed as sources of energy for the upper atmosphere at high latitudes. Electrodynamic heating in the thermosphere is described by a generalized energy balance equation taking into account a variety of inelastic processes and energy losses, and the use of height-integrated values of the Joule heating rate to estimate the importance of electrodynamic heating at high latitudes is discussed. Observations of electrons between 95 and 115 km altitude that are up to 1000 K hotter than the neutral atmosphere is presented as evidence for atmospheric heating due to unstable plasma waves arising from the Farley-Buneman modified two-stream instability.

  5. 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.

  6. Atmospheric contamination

    International Nuclear Information System (INIS)

    It is about the levels of contamination in center America, the population's perception on the problem, effects of the atmospheric contamination, effects in the environment, causes of the atmospheric contamination, possibilities to reduce the atmospheric contamination and list of Roeco Swisscontac in atmospheric contamination

  7. 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?

    OpenAIRE

    Kurbel, Sven

    2014-01-01

    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. Trans...

  8. Substrate selection for optimum qualitative and quantitative single atmospheric particles analysis using nano-manipulation, sequential thin-window electron probe X-ray microanalysis and micro-Raman spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Godoi, Ricardo Henrique Moreton [Graduate Program in Environmental Management, Centro Universitario Positivo-UnicenP R., Prof. Pedro Viriato Parigot de Souza, 5300, Campo Comprido, Curitiba-PR-CEP 81280-330 (Brazil); School of Chemistry, University of the Witwatersrand, Private Bag X 3, Wits, 2050 (South Africa); Potgieter-Vermaak, Sanja [Graduate Program in Environmental Management, Centro Universitario Positivo-UnicenP R., Prof. Pedro Viriato Parigot de Souza, 5300, Campo Comprido, Curitiba-PR-CEP 81280-330 (Brazil) and School of Chemistry, University of the Witwatersrand, Private Bag X 3, Wits, 2050 (South Africa)]. E-mail: sanja.potgieter@ua.ac.be; Hoog, Johan de [Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium); Kaegi, Ralf [EMPA, Swiss Federal Laboratories for Materials Testing and Research, Ueberlandstrasse 129, Dubendorf, CH-8600 (Switzerland); Grieken, Rene van [Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium)

    2006-04-15

    Sequential electron probe X-ray microanalysis using thin-window energy dispersive X-ray detection (TW-EDX-EPMA) and micro-Raman spectrometry (MRS) on the same atmospheric particle using nano-manipulation, is demonstrated. The advantageous combination of these two techniques allows information on the morphology, size, elemental and molecular composition, as well as the molecular structure of the same individual particle with a diameter as small as 500 nm. The use of an ultra-thin atmospheric window and a cold stage in EPMA enables qualitative and quantitative analysis of low-Z elements like C, N, and O as well as higher-Z elements. The work illustrates substrate optimisation and subsequent application in the analysis of atmospheric particles. Particle relocation was achieved by manipulative transfer onto transmission electron microscope grids, in an environmental scanning electron microscope, using 100 nm glass tips. A moderate correlation between the elemental composition obtained by TW-EDX-EPMA and the molecular fingerprint obtained by MRS is illustrated and its useful application in the interpretation of indoor air quality is discussed.

  9. 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.

  10. 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)

  11. Global Change in the Upper Atmosphere

    Science.gov (United States)

    Qian, L.; Solomon, S. C.; Lastovicka, J.; Roble, R. G.

    2011-12-01

    Anthropogenic increases of greenhouse gases warm the troposphere but have a cooling effect in the middle and upper atmosphere. The steady increase of CO2 is the dominant cause of upper atmosphere trends. Long-term changes of other radiatively active trace gases such as CH4, O3, and H2O, long-term changes of geomagnetic and solar activity, and other possible drivers also play a role. Observational and model studies have confirmed that in the past several decades, global cooling has occurred in the mesosphere and thermosphere; the cooling and contraction of the upper atmosphere has lowered the ionosphere, increased electron density in the lower ionosphere, but slightly decreased electron density in the upper ionosphere. Limited observations have suggested long-term changes in the occurrence rate of major stratospheric warming, mesosphere and lower thermosphere dynamics, wave activities and turbulence in the mesosphere and lower thermosphere, and occurrence of noctilucent clouds or polar mesospheric clouds. However, possible long-term changes of these parameters remain to be open questions due to lack of measurements. We will review recent progress in observations and simulations of global change in the upper atmosphere, and discuss future investigations with a focus on how measurements by commercial reusable suborbital vehicles can help resolve the open questions.

  12. 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.

  13. Initial PVO Evidence of Electron Depletion Signatures Downstream of Venus

    Science.gov (United States)

    Intriligator, D. S.; Hartle, R. E.; Perez-de-Tejada, H.; Siscoe, G. L.

    1993-01-01

    This first analysis of Pioneer Venus Orbiter (PVO) plasma analyzer electron measurements obtained in early 1992 during the PVO entry phase of the mission indicates the presence downstream from the terminator of a depletion or "bite out" of energetic ionosheath electrons similar to that observed on Mariner 10. There is more than one possible explanation for this energetic electron depletion. If it is due to atmospheric scattering, the electrons traveling along draped magnetic flux tubes that thread through the Venus neutral atmosphere would lose energy from impact ionization with oxygen. The cross-section for such electron impact ionization of oxygen has a peak near 100 eV, and it remains high above this energy, so atmospheric loss could provide a natural process for electrons at these energies to be selectively removed. In this case, our results are consistent with the Kar et al. (1994) study of PVO atmospheric entry ion mass spectrometer data which indicates that electron impact plays a significant role in maintaining the nightside ionosphere. Although it is appealing to interpret the energetic electron depletion in terms of direct atmospheric scattering, alternatively it could result from strong draping which connects the depletion region magnetically to the weak downstream bow shock and thereby reduces the electron source strength.

  14. Generation of runaway electrons and X-ray emission during breakdown of atmospheric-pressure air by voltage pulses with an ∼0.5-μs front duration

    International Nuclear Information System (INIS)

    Results are presented from experiments on the generation of runaway electron beams and X-ray emission in atmospheric-pressure air by using voltage pulses with an ∼0.5-μs front duration. It is shown that the use of small-curvature-radius spherical cathodes (or other cathodes with small curvature radii) decreases the intensity of the runaway electron beam and X-ray emission. It is found that, at sufficiently high voltages at the electrode gap (Um ∼ 100 kV), the gap breakdown, the formation of a spark channel, and the generation of a runaway electron beam occur over less than 10 ns. At high values of Um behind the anode that were reached by increasing the cathode size and the electrode gap length, a supershort avalanche electron beam with a full width at half-maximum (FWHM) of up to ∼100 ps was detected. At voltages of ∼50 kV, the second breakdown regime was revealed in which a runaway electron beam with an FWHM of ∼2 ns was generated, whereas the FWHM of the X-ray pulse increased to ∼100 ns. It is established that the energy of the bulk of runaway electrons decreases with increasing voltage front duration and is ⩽30 keV in the first regime and ⩽10 keV in the second regime

  15. Thin layer a-Al{sub 2}O{sub 3}:C beta dosemeters for the assessment of current dose rate in teeth due to {sup 90}Sr intake and comparison with electron paramagnetic resonance dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Goksu, H.Y.; Semiochkina, N.; Shiskina, E.A.; Wieser, A.; El-Faramawy, N.A.; Degteva, M.O.; Jacob, P.; Ivanov, D.V

    2002-07-01

    The use of thin-layer a-Al{sub 2}O{sub 3}:C thermoluminescence detectors (TLDs) for the assessment of current beta dose rate in human teeth due to {sup 90}Sr intake is investigated. The teeth used in this study were collected from members of the Techa river population who were exposed to radiation as a result of releases of the Mayak plutonium production facilities (Southern Urals-Russia) between 1949 and 1956. The beta dose rates from different parts of the tooth (enamel, crown dentine, and root) were determined by storing the detectors over the samples in a shielded environment. The cumulative dose measured by electron paramagnetic resonance (EPR) in different dental tissues is found to be proportional to the current dose rate obtained from a-Al{sub 2}O{sub 3}:C thermoluminescence dosemeters. The retention of {sup 90}Sr in various parts of the teeth is discussed. (author)

  16. Thin layer a-Al2O3:C beta dosemeters for the assessment of current dose rate in teeth due to 90Sr intake and comparison with electron paramagnetic resonance dosimetry

    International Nuclear Information System (INIS)

    The use of thin-layer a-Al2O3:C thermoluminescence detectors (TLDs) for the assessment of current beta dose rate in human teeth due to 90Sr intake is investigated. The teeth used in this study were collected from members of the Techa river population who were exposed to radiation as a result of releases of the Mayak plutonium production facilities (Southern Urals-Russia) between 1949 and 1956. The beta dose rates from different parts of the tooth (enamel, crown dentine, and root) were determined by storing the detectors over the samples in a shielded environment. The cumulative dose measured by electron paramagnetic resonance (EPR) in different dental tissues is found to be proportional to the current dose rate obtained from a-Al2O3:C thermoluminescence dosemeters. The retention of 90Sr in various parts of the teeth is discussed. (author)

  17. 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...

  18. Heterogeneous atmospheric chemistry

    Science.gov (United States)

    Schryer, D. R.

    1982-01-01

    The present conference on heterogeneous atmospheric chemistry considers such topics concerning clusters, particles and microparticles as common problems in nucleation and growth, chemical kinetics, and catalysis, chemical reactions with aerosols, electron beam studies of natural and anthropogenic microparticles, and structural studies employing molecular beam techniques, as well as such gas-solid interaction topics as photoassisted reactions, catalyzed photolysis, and heterogeneous catalysis. Also discussed are sulfur dioxide absorption, oxidation, and oxidation inhibition in falling drops, sulfur dioxide/water equilibria, the evidence for heterogeneous catalysis in the atmosphere, the importance of heterogeneous processes to tropospheric chemistry, soot-catalyzed atmospheric reactions, and the concentrations and mechanisms of formation of sulfate in the atmospheric boundary layer.

  19. Pluto's atmosphere

    International Nuclear Information System (INIS)

    Airborne CCD photometer observations of Pluto's June 9, 1988 stellar occultation have yielded an occultation lightcurve, probing two regions on the sunrise limb 2000 km apart, which reveals an upper atmosphere overlying an extinction layer with an abrupt upper boundary. The extinction layer may surround the entire planet. Attention is given to a model atmosphere whose occultation lightcurve closely duplicates observations; fits of the model to the immersion and emersion lightcurves exhibit no significant derived atmosphere-structure differences. Assuming a pure methane atmosphere, surface pressures of the order of 3 microbars are consistent with the occultation data. 43 references

  20. 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

  1. Atmospheric neutrinos and neutrino oscillations

    International Nuclear Information System (INIS)

    The results on the composition of atmospheric neutrinos interacting in underground detectors and on the rate of atmospheric muon neutrino interactions in the earth surrounding the detectors are reviewed. So far, systematic errors on the neutrino flux and on the electrons and muons neutrino interaction identifications are not yet reliable enough to prove that atmospheric neutrinos oscillate before being detected. (author) 22 refs., 5 figs

  2. Applications of theoretical methods in atmospheric science

    DEFF Research Database (Denmark)

    Johnson, Matthew Stanley; Goodsite, Michael E.

    2008-01-01

    Theoretical chemistry involves explaining chemical phenomenon using natural laws. The primary tool of theoretical chemistry is quantum chemistry, and the field may be divided into electronic structure calculations, reaction dynamics and statistical mechanics. These three all play a role in...... addressing an issue of primary concern: understanding photochemical reaction rates at the various conditions found in the atmosphere. Atmospheric science includes both atmospheric chemistry and atmospheric physics, meteorology, climatology and the study of extraterrestrial atmospheres....

  3. X-ray fluxes in the atmosphere

    International Nuclear Information System (INIS)

    A short review of X-rays measurements in the atmosphere is presented. In this context, the measurements obtained with NaI (Tl) scintillation detectors on board stratospheric balloons launched from Sao Jose dos Campos - Brazil in 1981, are considered as a first evidence of X-rays related to natural electron precipitation at the South Atlantic Magnetic Anomaly. Finally, a comparison of the related fluxes with those due to other sources, at balloon altitudes and at energies around 50KeV, is also given. (Author)

  4. 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.

  5. Breakdown of atmospheric pressure microgaps at high excitation frequencies

    International Nuclear Information System (INIS)

    Microwave (mw) breakdown of atmospheric pressure microgaps is studied by a one-dimensional Particle-in-Cell Monte Carlo Collisions numerical model. The effect of both field electron emission and secondary electron emission (due to electron impact, ion impact, and primary electron reflection) from surfaces on the breakdown process is considered. For conditions where field emission is the dominant electron emission mechanism from the electrode surfaces, it is found that the breakdown voltage of mw microdischarge coincides with the breakdown voltage of direct-current (dc) microdischarge. When microdischarge properties are controlled by both field and secondary electron emission, breakdown voltage of mw microdischarge exceeds that of dc microdischarge. When microdischarge is controlled only by secondary electron emission, breakdown voltage of mw microdischarge is smaller than that of dc microdischarge. It is shown that if the interelectrode gap exceeds some critical value, mw microdischarge can be ignited only by electrons initially seeded within the gap volume. In addition, the influence of electron reflection and secondary emission due to electron impact is studied

  6. Cosmic-ray-driven electron-induced reactions of halogenated molecules adsorbed on ice surfaces: Implications for atmospheric ozone depletion and global climate change

    International Nuclear Information System (INIS)

    The cosmic-ray-driven electron-induced reaction of halogenated molecules adsorbed on ice surfaces has been proposed as a new mechanism for the formation of the polar ozone hole. Here, experimental findings of dissociative electron transfer reactions of halogenated molecules on ice surfaces in electron stimulated desorption, electron trapping and femtosecond time-resolved laser spectroscopic measurements are reviewed. This is followed by a review of the evidence from recent satellite observations of this new mechanism for the Antarctic ozone hole, and all other possible physical mechanisms are discussed. Moreover, new observations of the 11-year cyclic variations of both polar ozone loss and stratospheric cooling and the seasonal variations of CFCs and CH4 in the polar stratosphere are presented, and quantitative predictions of the Antarctic ozone hole in the future are given. Finally, a new observation of the effects of CFCs and cosmic-ray-driven ozone depletion on global climate change is also presented and discussed.

  7. Reconstruction of energetic electron spectra in the upper atmosphere: balloon observations of auroral X-rays coordinated with measurements from the EISCAT radar

    International Nuclear Information System (INIS)

    Energetic electron precipitation in the auroral zone has been studied using coordinated auroral X-ray measurements from balloons, altitude profiles of the ionospheric electron density measured by the EISCAT radar above the balloons, and cosmic noise absorption data from the Scandinavian riometer network. The data were obtained during the Coordinated EISCAT and Balloon Observations (CEBO) campaign in August 1984. The energy spectral variations of both the X-ray fluxes and the primary precipitating electrons were examined for two precipitation events in the morning sector. As far as reasonably can be concluded from observations of magnetic activity in the auroral zone, and from the temporal development of the energy spectra, the two precipitation events can be interpreted in the frame of present models of energetic electron precipitation on the mordning side of the auroral zone. 96 refs., 70 figs., 11 tabs

  8. The origin of atmosphere

    International Nuclear Information System (INIS)

    The evolution of the atmosphere of the Earth is described. Starting from the hot Universe the main steps of the ''cooling-down'' process as the different states of the condensation of the matter are discussed. After this nuclear evolution the chemical evolution could start on the solid Earth's crust. In the reductive primordial atmosphere mainly due to ultraviolet rays the basic molecules for life as sugars and amino acids were formed. The photosynthesis of the plants has later produced the oxygen being present in the recent atmosphere. The question whether the pollution could affect the auto-stabilization loop of the atmosphere is also discussed. Finally the possibility of life on the Mars is studied. (Sz.Z.)

  9. Detection of traveling ionospheric disturbances induced by atmospheric gravity waves using the global positioning system

    Science.gov (United States)

    Bassiri, Sassan; Hajj, George A.

    Natural and man-made events like earthquakes and nuclear explosions launch atmospheric gravity waves (AGW) into the atmosphere. Since the particle density decreases exponentially with height, the gravity waves increase exponentially in amplitude as they propagate toward the upper atmosphere and ionosphere. As atmospheric gravity waves approach the ionospheric heights, the neutral particles carried by gravity waves collide with electrons and ions, setting these particles in motion. This motion of charged particles manifests itself by wave-like fluctuations and disturbances that are known as traveling ionospheric disturbances (TID). The perturbation in the total electron content due to TID's is derived analytically from first principles. Using the tilted dipole magnetic field approximation and a Chapman layer distribution for the electron density, the variations of the total electron content versus the line-of-sight direction are numerically analyzed. The temporal variation associated with the total electron content measurements due to AGW's can be used as a means of detecting characteristics of the gravity waves. As an example, detection of tsunami generated earthquakes from their associated atmospheric gravity waves using the Global Positioning System is simulated.

  10. Production of the Titan plasma tail due to the ionization velocity phenomenon

    International Nuclear Information System (INIS)

    The critical ionization velocity phonomenon is proposed to account for anomalous interaction of the Titan's atmosphere with the magnetospheric plasma corotating with Saturn. Lower hybrid instability, due to counterstreaming of magnetospheric plasma and newly produced ions, plays there the main role. However, the effects of charge separation due to very large gyroradius of newly produced nitrogen ions also may be the source of instability. Kinetic energy of newly produced ions is transferred to electrons via the plasma waves excited by counnerstreaming ions. This yields to the excitation of atmospheric atoms and their radiation. The limiting plasma density, the electron temperatures as well as the freguency spectrum of the excited waves are determined and compared with the measurements

  11. Reconstruction of energetic electron spectra in the upper atmosphere: balloon observations of auroral X-rays coordinated with measurements from the Eiscat radar

    International Nuclear Information System (INIS)

    Energetic electron precipitation in the auroral zone has been studied using coordinated auroral X-ray measurements from balloons, altitude profiles of the ionospheric electron density measured by the EISCAT radar above the balloons, and cosmic noise absorption data from the Scandinavian riometer network. The data were obtained during the coordinated EISCAT and balloon observation campaign in August 1984. A method by which an estimate of the energy spectrum of precipitating energetic electrons can be obtained from balloon measurements of bremsstrahlung X-rays is described. The energy spectral variation of both the X-ray fluxes and the primary precipitating electrons were examined for two precipitation events in the morning sector. As far as reasonably can be concluded from observations of magnetic activity in the auroral zone, and from the temporal development of the energy spectra, the two precipitation events can be interpreted in the frame of present models of energetic electron precipitation on the morning side of the auroral zone. 96 refs

  12. 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.

  13. 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......” implications and qualities of the approach are identified through concrete examples of a design case, which also investigates the qualities and implications of addressing atmospheres both as design concern and user experience....

  14. Exoplanetary Atmospheres

    CERN Document Server

    Madhusudhan, Nikku; Fortney, Jonathan; Barman, Travis

    2014-01-01

    The study of exoplanetary atmospheres is one of the most exciting and dynamic frontiers in astronomy. Over the past two decades ongoing surveys have revealed an astonishing diversity in the planetary masses, radii, temperatures, orbital parameters, and host stellar properties of exoplanetary systems. We are now moving into an era where we can begin to address fundamental questions concerning the diversity of exoplanetary compositions, atmospheric and interior processes, and formation histories, just as have been pursued for solar system planets over the past century. Exoplanetary atmospheres provide a direct means to address these questions via their observable spectral signatures. In the last decade, and particularly in the last five years, tremendous progress has been made in detecting atmospheric signatures of exoplanets through photometric and spectroscopic methods using a variety of space-borne and/or ground-based observational facilities. These observations are beginning to provide important constraints...

  15. Electrical cycle in the Earth's atmosphere

    International Nuclear Information System (INIS)

    A qualitative physical picture of atmospheric electricity as a secondary phenomenon of atmospheric water circulation is presented using the key electrical atmospheric processes, their average observed parameters, and a detailed analysis of separate processes as the basis. The electrical processes begin with the charging of aerosols at kilometer altitudes due to aerosols of different aggregate states colliding with one another. Atmospheric electric currents arise from the fall speed difference (in cumulus clouds) between mass-different positively and negatively charged aerosols, resulting in aerosols with a negative charge of, on average, (25-30)e at the lower edge of a cloud. This creates an electric field between Earth and the cloud, and the subsequent penetration of streams of warm wet air into the cloud causes the atmosphere to electrically break down, thus producing lightning flashes. At the same time, these processes cause aerosols to grow and to fall as rain onto Earth. Processes in atmospheric air, including those involving aerosols, electrons, and ions, provide a unified physical picture of electric phenomena in the terrestrial atmosphere. (reviews of topical problems)

  16. Staging atmospheres

    DEFF Research Database (Denmark)

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

    2015-01-01

    . Nevertheless, people’s experience of the environment is sought manipulated in a variety of contexts, often without offering a less ‘true’ experience of a situation than if it had not been manipulated by people. In fact, orchestrations of space are often central to sociality, politics and aesthetics. 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...

  17. Enhancement of two dimensional electron gas concentrations due to Si3N4 passivation on Al0.3Ga0.7N/GaN heterostructure: strain and interface capacitance analysis

    Directory of Open Access Journals (Sweden)

    Syed Mukulika Dinara

    2015-04-01

    Full Text Available Enhancement of two dimensional electron gas (2DEG concentrations at Al0.3Ga0.7N/GaN hetero interface after a-Si3N4 (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 Al0.3Ga0.7N 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 Al0.3Ga0.7N 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 Al0.3Ga0.7N layer and also due to the decreased surface states at the interface of SiN/Al0.3Ga0.7N layer, effectively improving the carrier confinement at the interface.

  18. 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

    V, it is shown that secondary electrons supply a significant contribution to the return current to the spacecraft and thereby reduce the spacecraft potential. Our numerical results are in good agreement with observations from the CHARGE-2 sounding rocket experiment.A more detailed study of the BAI as it...

  19. Dynamics in Atmospheric Physics

    Science.gov (United States)

    Lindzen, Richard A.

    2005-08-01

    Motion is manifest in the atmosphere in an almost infinite variety of ways. In Dynamics in Atmospheric Physics, Dr. Richard Lindzen describes the nature of motion in the atmosphere, develops fluid dynamics relevant to the atmosphere, and explores the role of motion in determining the climate and atmospheric composition. The author presents the material in a lecture note style, and the emphasis throughout is on describing phenomena that are at the frontiers of current research, but due attention is given to the methodology of research and to the historical background of these topics. The author's treatment and choice of topics is didactic. Problems at the end of each chapter will help students assimilate the material. In general the discussions emphasize physical concepts, and throughout Dr. Lindzen makes a concerted effort to avoid the notion that dynamic meteorology is simply the derivation of equations and their subsequent solution. His desire is that interested students will delve further into solution details. The book is intended as a text for first year graduate students in the atmospheric sciences. Although the material in the book is self contained, a familiarity with differential equations is assumed; some background in fluid mechanics is helpful.

  20. Accurate gamma and MeV-electron track reconstruction with an ultra-low diffusion Xenon/TMA TPC at 10 atmospheres

    CERN Document Server

    Gonzalez-Diaz, 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 ...

  1. 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...

  2. Surface degradetion of complex architectural form due to atmospheric pollution

    Czech Academy of Sciences Publication Activity Database

    Pospíšil, Stanislav; Drdácký, Miloš; Slížková, Zuzana; Knotková, D.; Delpech, P.

    London : Taylor and Francis/Balkema, 2006 - (Fort, R.; Alvarez de Buergo, M.; Gomez-Heras, M.; Vazquez-Calvo, C.), s. 447-452 ISBN 978-0-415-45134-5. [Heritage, Weathering and Conservation, HWC-2006. Madrid (ES), 21.06.2006-24.06.2006] Grant ostatní: evropská komise(XE) HPRI-CT-2002-00199; evropská komise(XE) SSPI-CT-2003-501837 Institutional research plan: CEZ:AV0Z20710524 Keywords : environmental conditions * Reims Cathedral * oxidation products Subject RIV: AL - Art, Architecture, Cultural Heritage

  3. Atmospheric Smell

    DEFF Research Database (Denmark)

    Stenslund, Anette

    awareness. Subsequently, visitor interviews revealed how a museum-staged hospital atmosphere of an art installation was directly addressed owing to its smell. Curiously, this observation speaks against prevailing literature portraying smell as the ‘mute sense’, and what is more, the museum display did not...... alter smell curatorially. Rather, smell was gestured through non-olfactory effects and it was put in words metonymically, gesturing a reversibly synaesthetic atmosphere of a hospital. Visitor conversations revealed how smell could be poignantly picked up in situ, yet not until frequenting the museum...

  4. 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...

  5. Global empirical models of ionospheric electron temperature in the upper F-region and plasmasphere based on in situ measurements from the Atmosphere Explorer-C, ISIS-1 and ISIS-2 satellites

    Science.gov (United States)

    Brace, L. H.; Theis, R. F.

    1981-01-01

    Langmuir probe measurements of electron temperature, T sub e, in the vicinity of 300, 400, 1400 and 3000 km from the Atmosphere Explorer-C and the ISIS satellites have been employed to construct empirical models of the global distribution of T sub e at each of these altitudes. Legendre polynomials are employed to describe the observations at solstice and equinox in terms of dip latitude and local time. Sources of T sub e variations, such as solar activity, magnetic activity and longitude are found to be of second order importance, although they are resolvable in some cases by comparisons of the data with the model. The behavior of T sub e at the altitudes of these models is discussed in terms of its implications for our understanding of the energy exchange between the F-region and the plasmasphere.

  6. 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...

  7. The ancient oxygen exosphere of Mars - Implications for atmosphere evolution

    Science.gov (United States)

    Zhang, M. H. G.; Luhmann, J. G.; Bougher, S. W.; Nagy, A. F.

    1993-01-01

    The paper considers absorption of oxygen (atoms and ions) by the surface as a mechanism for the early Martian atmosphere escape, due to the effect of high EUV flux of the ancient sun. Hot oxygen exosphere densities in ancient atmosphere and ionosphere are calculated for different EUV fluxes and the escape fluxes associated with these exposures. Using these densities, the ion production rate above the ionopause is calculated for different epochs including photoionization, charge exchange, and solar wind electron impact. It is found that, when the inferred high solar EUV fluxes of the past are taken into account, oxygen equivalent to that in several tens of meters of water, planet-wide, should have escaped Martian atmosphere to space over the last 3 Gyr.

  8. Apparatus and method for generating high density pulses of electrons

    International Nuclear Information System (INIS)

    An apparatus and method are described for the production of high density pulses of electrons using a laser energized emitter. Caesium atoms from a low pressure vapour atmosphere are absorbed on and migrate from a metallic target rapidly heated by a laser to a high temperature. Due to this heating time being short compared with the residence time of the caesium atoms adsorbed on the target surface, copious electrons are emitted which form a high current density pulse. (U.K.)

  9. Atmospheric pressure plasma jet for liquid spray treatment

    Science.gov (United States)

    Mitić, S.; Philipps, J.; Hofmann, D.

    2016-05-01

    Atmospheric pressure plasma jets have been intensively studied in recent years due to growing interest in their use for biomedical applications and surface treatments. Either surfaces can be treated by a plasma jet afterglow for cleaning or activation or a material can be deposited by a reactive gas component activated by plasma. Effects of plasma on liquid have been reported several times where the electron spin trapping method was used for radical detection. Here we propose another method of liquid treatment using the atmospheric pressure plasma jet. In the device presented here, liquid was sprayed in droplets from an inner electrode directly into a plasma jet where it was treated and sprayed out by gas flow. Optical end electrical measurements were done for diagnostics of the plasma while electron paramagnetic resonance measurements were used for detection of radicals (\\text{OH},\\text{OOH},\\text{CH} ) produced by plasma treatment of liquids.

  10. 大气压介质阻挡放电中电子碰撞电离系数α的测定%Preliminary Measurement of Electron Impact Ionization Coefficient in Gases at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    冉俊霞; 罗海云; 梁卓; 王新新

    2012-01-01

    电子碰撞电离系数α是气体放电研究中的一个重要物理参数,但现有的α系数数值都是在低气压Townsend放电实验中得到的,它们不适用于大气压下气体放电。为了尝试解决这个问题,提出了一种大气压下α系数的光学测量方法,它借助介质阻挡电极结构,在某些大气压气体中产生瞬态或稳态Townsend放电,利用带像增强器高速数码相机的纳秒曝光功能,记录气隙中瞬态发光强度空间分布,并与Townsend放电对应的理论发光强度分布进行比较,根据两者的最佳拟合效果推导出α系数。该方法被用于测定大气压氮气α系数,结果表明其基本可行,但仍需继续加以完善。%Electron impact ionization coefficient a is one of the most important parameters used in the study of gas discharge. However, the a values usually determined in the experiments on Townsend discharge in gases at low pressure are not applicable to the gas discharges in atmospheric gases. Aiming at solving this problem, a method for determining the a values in the gases at atmospheric pressure was proposed. Dielectric barrier Townsend discharges were produced in some gases at atmospheric pressure. The distribution of the light intensity in the discharge gap was recorded by taking side-view photograph using an ICCD camera with an extremely short exposure time and compared with the theoretical distributions with different presumed ~. The a value was determined by the best fitting of the theoretical distribution to the experimental one. The method was proved to be applicable in the determination of a for nitrogen at atmospheric pressure.

  11. 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.

  12. Atmospheric and aerosol chemistry

    International Nuclear Information System (INIS)

    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.

  13. Atmospheric levels and cytotoxicity of PAHs and heavy metals in TSP and PM 2.5 at an electronic waste recycling site in southeast China

    Science.gov (United States)

    Deng, W. J.; Louie, P. K. K.; Liu, W. K.; Bi, X. H.; Fu, J. M.; Wong, M. H.

    Twenty-nine air samples of total suspended particles (TSP, particles less than 30-60 μm) and thirty samples of particles with aerodynamic diameter smaller than 2.5 μm (PM 2.5) were collected at Guiyu, an electronic waste (e-waste) recycling site in southeast China from 16 August 2004 to 17 September 2004. The results showed that mass concentrations contained in TSP and PM 2.5 were 124±44.1 and 62.12±20.5 μg m -3, respectively. The total sum of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) associated with TSP and PM 2.5 ranged from 40.0 to 347 and 22.7 to 263 ng m -3, respectively. Five-ring and six-ring PAHs accounted for 73% of total PAHs. The average concentration of benzo(a) pyrene was 2-6 times higher than in other Asian cities. Concentrations of Cr, Cu and Zn in PM 2.5 of Guiyu were 4-33 times higher than in other Asian countries. In general, there were significant correlations between concentrations of individual contaminants in TSP with PM 2.5 (i.e. PAHs, Cd, Cr, Cu, Pb, Zn, Mn except Ni and As). The high concentrations of both PAHs and heavy metals in air of Guiyu may impose a serious environmental and health concern. Cytotoxicity of the extract of TSP and PM 2.5 of ten 24 h samples collected against human promonocytic leukemia cell line U937 (ATCC 1593.2) was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cytotoxicity assay. The results showed that under the same concentrations of extract, PM 2.5 cytotoxicity was 2-4 times higher than TSP.

  14. Atmospheric electricity and aerosol-cloud interactions in earth's atmosphere

    Science.gov (United States)

    Manninen, Hanna E.; Tammet, Hannes; Mäkelä, Antti; Haapalainen, Jussi; Mirme, Sander; Nieminen, Tuomo; Franchin, Alessandro; Petäjä, Tuukka; Kulmala, Markku; Hõrrak, Urmas

    2013-05-01

    Firstly, atmospheric ions play an important role in the fair weather electricity in Earth's atmosphere. Small ions, or charged molecular clusters, carry electric currents in the atmosphere. These small ions are continuously present, and their lifetime in lower atmosphere is about one minute. It's essential to find out a connection between the production rate of cluster ions, ion-ion recombination, and ion-aerosol attachment, and their ambient concentrations, in order to understand electrical properties of air. Secondly, atmospheric ions are important for Earth's climate, due to their potential role in secondary aerosol formation, which can lead to increased number of cloud condensation nuclei (CCN), which in turn can change the cloud properties. Our aim is to quantify the connections between these two important roles of air ions based on field observations.

  15. Computational studies for plasma filamentation by magnetic field in atmospheric microwave discharge

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Masayuki; Ohnishi, Naofumi [Department of Aerospace Engineering, Tohoku University, Sendai 980-8579 (Japan)

    2014-12-01

    Plasma filamentation is induced by an external magnetic field in an atmospheric discharge using intense microwaves. A discrete structure is obtained at low ambient pressure if a strong magnetic field of more than 1 T is applied, due to the suppression of electron diffusion, whereas a diffusive pattern is generated with no external field. Applying a magnetic field can slow the discharge front propagation due to magnetic confinement of the electron transport. If the resonance conditions are satisfied for electron cyclotron resonance and its higher harmonics, the propagation speed increases because the heated electrons easily ionize neutral particles. The streamer velocity and the pattern of the microwave plasma are positively controlled by adjusting two parameters—the electron diffusion coefficient and the ionization frequency—through the resonance process and magnetic confinement, and hot, dense filamentary plasma can be concentrated in a compact volume to reduce energy loss in a plasma device like a microwave rocket.

  16. Climate and atmospheric research

    International Nuclear Information System (INIS)

    This issue of the scientific journal of the Humboldt university is dedicated to results of research work carried out to the greatest extent at the meteorological institute in the last two years on the area of climate and atmospheric research. The traditional research areas of the institute are climatology and the dynamics of the atmosphere, in particular the atmospherical boundary layer. Considering the high probability of a global climatic fluctuation due to the anthropogenic change of composition of the atmosphere and other climate-relevant factors imminent in the next century, climatological research today is an important part of global and regional environmental research. From the necessity of determination and evaluation of the effect of climatic fluctuations on nature and society the contours of a new interdisciplinary research area are already visible now. This is suitable as hardly any other area to be the supporting idea of environmental research at universities. The contributions contained in the issue already consider, in addition to results on climate diagnosis, also results on aspects of climate effect research. (orig./KW)

  17. 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.

  18. 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.

  19. Detection techniques for tenuous planetary atmospheres

    Science.gov (United States)

    Hoenig, S. A.

    1972-01-01

    The research for the development of new types of detectors for analysis of planetary atmospheres is summarized. Topics discussed include: corona discharge humidity detector, surface catalysis and exo-electron emission, and analysis of soil samples by means of exo-electron emission. A report on the exo-electron emission during heterogeneous catalysis is included.

  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. Atmospheric Release Advisory Capability

    International Nuclear Information System (INIS)

    The Atmospheric Release Advisory Capability (ARAC) project is a Department of Energy (DOE) sponsored real-time emergency response service available for use by both federal and state agencies in case of a potential or actual atmospheric release of nuclear material. The project, initiated in 1972, is currently evolving from the research and development phase to full operation. Plans are underway to expand the existing capability to continuous operation by 1984 and to establish a National ARAC Center (NARAC) by 1988. This report describes the ARAC system, its utilization during the past two years, and plans for its expansion during the next five to six years. An integral part of this expansion is due to a very important and crucial effort sponsored by the Defense Nuclear Agency to extend the ARAC service to approximately 45 Department of Defense (DOD) sites throughout the continental US over the next three years

  2. Use of electron ionization and atmospheric pressure chemical ionization in gas chromatography coupled to time-of-flight mass spectrometry for screening and identification of organic pollutants in waters.

    Science.gov (United States)

    Portolés, Tania; Mol, Johannes G J; Sancho, Juan V; Hernández, Félix

    2014-04-25

    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 promoted by the APCI source allows effective and wide-scope screening based on the investigation of the molecular ion and/or protonated molecule. This is in contrast to electron ionization (EI) where ionization typically results in extensive fragmentation, and diagnostic ions and/or spectra need to be known a priori to facilitate detection of the analytes in the raw data. Around 170 organic contaminants from different chemical families were initially investigated by both approaches, i.e. GC-(EI)TOF and GC-(APCI)QTOF, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and a notable number of pesticides and relevant metabolites. The new GC-(APCI)QTOF MS approach easily allowed widening the number of compounds investigated (85 additional compounds), with more pesticides, personal care products (UV filters, musks), polychloronaphthalenes (PCNs), antimicrobials, insect repellents, etc., most of them considered as emerging contaminants. Both GC-(EI)TOF and GC-(APCI)QTOF methodologies have been applied, evaluating their potential for a wide-scope screening in the environmental field. PMID:24674644

  3. Macrocluster desorption effect caused by single MCI: charges of gold clusters (2-20 nm) desorbed due to electronic processes induced by fission fragment bombardment in nanodispersed gold targets

    International Nuclear Information System (INIS)

    In this work the charge state of the negatively charged gold nanocluster ions (2-20 nm) that were desorbed from nanodispersed gold islet targets by 252Cf fission fragments via electronic processes is studied. Mean cluster charge was calculated as a ratio of mean cluster mass to mean mass-to-charge ratio . Cluster masses were measured by means of a collector technique employing transmission electron microscopy and scanning force microscopy, while m/q was measured by means of a tandem TOF-spectrometer. It is shown that the nanocluster ions are mostly multiply charged (2-16e) and the charge increases non-linearly with the cluster size. The results are discussed

  4. Operational constraints and strategies for systems to effect the sustainable, solar-driven reduction of atmospheric CO_2

    OpenAIRE

    Chen, Yikai; Lewis, Nathan S.; Xiang, Chengxiang

    2015-01-01

    The operational constraints for a 6-electron/6-proton CO_2 reduction system that operates at the concentration of CO_2 in the current atmosphere (p_(CO_2) = 400 ppm) have been evaluated on a variety of scale lengths that span from laboratory scale to global scale. Due to the low concentration of CO_2 in the atmosphere, limitations due to mass transport of CO_2 from the tropopause have been evaluated through five different regions, each with different characteristic length scales: the troposph...

  5. 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)

  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. 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.

  8. 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)].

  9. 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

  10. Ionization in Earth's atmosphere following the solar storm on January 20, 2005

    Science.gov (United States)

    Seripienlert, A.; Mitthumsiri, W.; Saiz, A.; Ruffolo, D. J.; Mangeard, P. S.; Tortermpun, U.

    2014-12-01

    To estimate possible effects of atmospheric ionization on clouds and Earth's climate as well as radiation exposure of air travelers and aircraft electronics due to space weather, relativistic solar ions are the only solar particles of concern because the less energetic particles do not penetrate to cloud/aircraft altitudes. Some solar storms produce relativistic ions that lead to showers of secondary particles in Earth's atmosphere and generate signals in ground-based detectors such as neutron monitors at a rate that can be observed above the background due to galactic cosmic rays, hence the term ground-level enhancements (GLEs). In this work we study the January 20, 2005 event, one of the most intense GLEs ever observed. From the bare counter to neutron monitor count rate ratio at South Pole, we estimate a spectral index in rigidity of 5.0. From the Spaceship Earth network, supplemented to comprise 13 polar neutron monitors, we model the time profile of relativistic solar ions impinging on Earth's atmosphere in the polar regions. We then perform Monte Carlo simulations using a realistic atmospheric model to determine ionization as a function of altitude and time in Earth's atmosphere. The results will allow us to investigate a possible connection between solar activity and Earth's climate as mediated by the cosmic ray flux, atmospheric ionization, and cloud formation. This work is partially supported by Thailand Research Fund and a Postdoctoral Fellowship from Mahidol University.

  11. Human due diligence.

    Science.gov (United States)

    Harding, David; Rouse, Ted

    2007-04-01

    Most companies do a thorough job of financial due diligence when they acquire other companies. But all too often, deal makers simply ignore or underestimate the significance of people issues in mergers and acquisitions. The consequences are severe. Most obviously, there's a high degree of talent loss after a deal's announcement. To make matters worse, differences in decision-making styles lead to infighting; integration stalls; and productivity declines. The good news is that human due diligence can help companies avoid these problems. Done early enough, it helps acquirers decide whether to embrace or kill a deal and determine the price they are willing to pay. It also lays the groundwork for smooth integration. When acquirers have done their homework, they can uncover capability gaps, points of friction, and differences in decision making. Even more important, they can make the critical "people" decisions-who stays, who goes, who runs the combined business, what to do with the rank and file-at the time the deal is announced or shortly thereafter. Making such decisions within the first 30 days is critical to the success of a deal. Hostile situations clearly make things more difficult, but companies can and must still do a certain amount of human due diligence to reduce the inevitable fallout from the acquisition process and smooth the integration. This article details the steps involved in conducting human due diligence. The approach is structured around answering five basic questions: Who is the cultural acquirer? What kind of organization do you want? Will the two cultures mesh? Who are the people you most want to retain? And how will rank-and-file employees react to the deal? Unless an acquiring company has answered these questions to its satisfaction, the acquisition it is making will be very likely to end badly. PMID:17432159

  12. 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...

  13. Dose due to 40K

    International Nuclear Information System (INIS)

    The dose due to 40K has been estimated. Potassium is one of the most abundant elements in nature, being approximately 2% of the Earth's crust. Potassium has three isotopes 39K, 40K and 41K, two are stable while 40K is radioactive with a half life of 1.2x109 years; there is 0.0117% 40K-to-K ratio. Potassium plays an important role in plants, animals and humans growth and reproduction. Due to the fact that K is an essential element for humans, 40K is the most abundant radioisotope in human body. In order to keep good health conditions K must be intake at daily basis trough food and beverages, however when K in ingested above the requirements produce adverse health effects in persons with renal, cardiac and hypertension problems or suffering diabetes. In 89.3% 40K decays to 40C through β-decay, in 10.3% decays through electronic capture and emitting 1.46 MeV γ-ray. K is abundant in soil, construction materials, sand thus γ-rays produced during 40K decay contribute to external dose. For K in the body practically all 40K decaying energy is absorbed by the body; thus 40K contributes to total dose in humans and it is important to evaluate its contribution. In this work a set of 40K sources were prepared using different amounts of KCl salt, a γ-ray spectrometer with a NaI(Tl) was characterized to standardized the sources in order to evaluate the dose due to 40K. Using thermoluminescent dosemeters the dose due to 40K was measured and related to the amount of 40K γ-ray activity. (Author)

  14. 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 de...

  15. Optical electronics

    Science.gov (United States)

    Javan, A.

    1976-01-01

    The development of an optical diode consisting of a metal-dielectric-metal junction in which the high-speed electric conduction process occurs due to quantum mechanical electron tunneling across the dielectric barrier is briefly reviewed. Potential applications of the diode are discussed.

  16. 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...

  17. 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...

  18. Communications Blackout Prediction for Atmospheric Entry of Mars Science Laboratory

    Science.gov (United States)

    Morabito, David; Edquist, Karl

    2005-01-01

    When a supersonic spacecraft enters a planetary atmosphere with v >> v(sub sound), a shock layer forms in the front of the body. An ionized sheath of plasma develops around the spacecraft, which results from the ionization of the atmospheric constituents as they are compressed and heated by the shock or heated within the boundary layer next to the surface. When the electron density surrounding the spacecraft becomes sufficiently high, communications can be disrupted (attenuation/blackout). During Mars Science Laboratory's (MSL's) atmospheric entry there will likely be a communication outage due to charged particles on the order of 60 to 100 seconds using a UHF link frequency looking out the shoulders of the wake region to orbiting relay asset. A UHF link looking out the base region would experience a shorter duration blackout, about 35 seconds for the stressed trajectory and possibly no blackout for the nominal trajectory. There is very little likelihood of a communications outage using X-band (however, X-band is not currently planned to be used during peak electron density phase of EDL).

  19. Ionization by Cosmic Rays in the Atmosphere of Titan

    Science.gov (United States)

    Norman, R. B.; Gronoff, G.; Mertens, C. J.; Blattnig, S.

    2011-12-01

    In-situ measurements by Cassini-Huygens have shown the importance of ionizing particles (solar photons, magnetospheric electrons and protons, cosmics rays) on the atmosphere of Titan. Ionizing particles play an important role in the atmospheric chemistry of Titan and must therefore be accurately modeled to understand the contribution of the differing sources of ionization. To model the initial galactic cosmic ray environment, the Badwar-O'Neill cosmic ray spectrum model was adapted for use at Titan. The Aeroplanets model, an electron transport model for the study of airglow and aurora, was then coupled to the Planetocosmics model, a Monte-carlo cosmic ray transport and energy deposition model, to compute ion production from cosmic rays. In addition, the NAIRAS model, a cosmic ray irradiation model adapted for fast computations, was adopted to the Titan environment and, for the first time, used to compute an ionization profile on a planet other than Earth and compared to the Planetocosmics results. For the first time, the importance of high charge cosmic rays on the ionization of the Titan atmosphere was demonstrated. High charge cosmic rays were found to be especially important below an altitude of 400 km, contributing significantly to the total ionization. Specifically, between 200 km and 400 km, alpha and higher charge cosmic rays are responsible for 40% of the ionization. The increase due to high charge cosmic rays was found for both the Planetocosmics and NAIRAS models.

  20. On monitoring the atmospheric greenhouse effect from space

    OpenAIRE

    Inamdar, A. K.; Ramanathan, V.

    2011-01-01

    We propose an analysis technique for monitoring the planetary greenhouse effect from space. 2 quantities are used as a measure of the atmospheric greenhouse effect: (1) Ga, which is the reduction in the clear sky outgoing longwave radiation (OLR) due to the atmosphere; it is the radiative heating of the surface-atmosphere column; (2) Ga*, which is the back radiation from the atmosphere to the surface; it is the radiative heating of the surface by the atmosphere. Ga is obtained from satellite ...

  1. 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.

  2. 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.

  3. The atmospheric escape at Mars: complementing the scenario

    Science.gov (United States)

    Lilensten, Jean; Simon, Cyril; Barthélémy, Mathieu; Thissen, Roland; Ehrenreich, David; Gronoff, Guillaume; Witasse, Olivier

    2013-04-01

    In the recent years, the presence of dications in the atmospheres of Mars, Venus, Earth and Titan has been modeled and assessed. These studies also suggested that these ions could participate to the escape of the planetary atmospheres because a large fraction of them is unstable and highly ener- getic. When they dissociate, their internal energy is transformed into kinetic energy which may be larger than the escape energy. This study assesses the impact of the doubly-charged ions in the escape of CO2-dominated planetary atmospheres and to compare it to the escape of thermal photo-ions.We solve a Boltzmann transport equation at daytime taking into account the dissociative states of CO++ for a simplified single constituent atmosphere of a 2 case-study planet. We compute the escape of fast ions using a Beer-Lambert approach. We study three test-cases. On a Mars-analog planet in today's conditions, we retrieve the measured electron escape flux. When comparing the two mechanisms (i.e. excluding solar wind effects, sputtering ...), the escape due to the fast ions issuing from the dissociation of dications may account for up to 6% of the total and the escape of thermal ions for the remaining. We show that these two mechanisms cannot explain the escape of the atmosphere since the magnetic field vanished but complement the other processes and allow writing the scenario of the Mars escape. We show that the atmosphere of a Mars analog planet would empty in another giga years and a half. At Venus orbit, the contribution of the dications in the escape rate is negligible.When simulating the hot Jupiter HD209458b, the two processes cannot explain the measured escape flux of C+.

  4. 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.

  5. Electrodynamical Coupling of Earth's Atmosphere and Ionosphere: An Overview

    Directory of Open Access Journals (Sweden)

    A. K. Singh

    2011-01-01

    Full Text Available Electrical processes occurring in the atmosphere couple the atmosphere and ionosphere, because both DC and AC effects operate at the speed of light. The electrostatic and electromagnetic field changes in global electric circuit arise from thunderstorm, lightning discharges, and optical emissions in the mesosphere. The precipitation of magnetospheric electrons affects higher latitudes. The radioactive elements emitted during the earthquakes affect electron density and conductivity in the lower atmosphere. In the present paper, we have briefly reviewed our present understanding of how these events play a key role in energy transfer from the lower atmosphere to the ionosphere, which ultimately results in the Earth's atmosphere-ionosphere coupling.

  6. 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.

  7. Dications and thermal ions in planetary atmospheric escape

    Science.gov (United States)

    Lilensten, J.; Simon Wedlund, C.; Barthélémy, M.; Thissen, R.; Ehrenreich, D.; Gronoff, G.; Witasse, O.

    2013-01-01

    In the recent years, the presence of dications in the atmospheres of Mars, Venus, Earth and Titan has been modeled and assessed. These studies also suggested that these ions could participate to the escape of the planetary atmospheres because a large fraction of them is unstable and highly energetic. When they dissociate, their internal energy is transformed into kinetic energy which may be larger than the escape energy. The goal of this study is to assess the impact of the doubly-charged ions in the escape of CO2-dominated planetary atmospheres and to compare it to the escape of thermal photo-ions. We solve a Boltzmann transport equation at daytime taking into account the dissociative states of CO2++ for a simplified single constituent atmosphere of a case-study planet. We compute the escape of fast ions using a Beer-Lambert approach. We study three test-cases. On a Mars-analog planet in today's conditions, we retrieve the measured electron escape flux. When comparing the two mechanisms (i.e. excluding solar wind effects, sputtering, etc.), the escape due to the fast ions issuing from the dissociation of dications may account for up to 6% of the total and the escape of thermal ions for the remaining. We show that these two mechanisms cannot explain the escape of the atmosphere since the magnetic field vanished and even contribute only marginally to this loss. We show that with these two mechanisms, the atmosphere of a Mars analog planet would empty in another giga years and a half. At Venus orbit, the contribution of the dications in the escape rate is negligible. When simulating the hot Jupiter HD 209458 b, the two processes cannot explain the measured escape flux of C+. This study shows that the dications may constitute a source of the escape of planetary atmospheres which had not been taken into account until now. This source, although marginal, is not negligible. The influence of the photoionization is of course large, but cannot explain alone the loss of Mars

  8. 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.

  9. AMBIPOLAR ELECTRIC FIELD, PHOTOELECTRONS, AND THEIR ROLE IN ATMOSPHERIC ESCAPE FROM HOT JUPITERS

    International Nuclear Information System (INIS)

    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. Modeling of atmospheric and ionospheric disturbances from shallow seismic sources

    Science.gov (United States)

    Davies, John Bruce; Archambeau, Charles B.

    Earthquake sources, as well as contained underground explosions and volcanic explosions, initiate atmospheric waves at the air-ground interface which propagate upward and outward. The propagating atmospheric waves produced are of two types: a high-frequency acoustic wave and a low-frequency gravity wave with horizontal wavelength much longer than its vertical wavelength. Because of the exponential decrease of atmospheric density with height, the acoustic and particularly the gravity waves can grow to significant amplitude in the upper atmosphere, where they can affect the ionosphere causing changes in the distribution of neutral and charged particles. The coherent fluctuations of electron densities and ionization layer boundaries produced by these waves can be detected by electromagnetic sounding methods and hence the occurrence and character of the disturbances can be inferred. A particular application of interest is the detection and discrimination of underground and near surface chemical explosions in a nuclear test monitoring context. Specifically, identification of the different source types is enhanced by combining seismic detection methods with detection of the ionospheric disturbances caused by explosion and earthquake sources. In this study, numerical models of non-linear gravity controlled atmospheric disturbances produced by seismic sources near the surface of the Earth are investigated in order to obtain quantitative predictions that might be used in evaluating detection methods based on gravity wave excitation. Explicit numerical integration of the non-linear finite difference equations is used to simulate the transient flows produced in a three-dimensional ARDC atmosphere. Results from the simulations agree with many results from linear theory approximations and also show non-linear characteristics similar to important gravity wave observations. Electron density changes in the ionosphere are predicted with their spatial and temporal behavior found to

  11. 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.

  12. Nucleation of atmospheric particles

    OpenAIRE

    Curtius J

    2009-01-01

    Two types of particles exist in the atmosphere, primary and secondary particles. While primary particles such as soot, mineral dust, sea salt particles or pollen are introduced directly as particles into the atmosphere, secondary particles are formed in the atmosphere by condensation of gases. The formation of such new aerosol particles takes place frequently and at a broad variety of atmospheric conditions and geographic locations. A considerable fraction of the atmospheric particles is form...

  13. 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

  14. Atmospheric neutrinos and discovery of neutrino oscillations

    International Nuclear Information System (INIS)

    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. (author)

  15. Atmospheric composition change: Ecosystems–Atmosphere interactions

    DEFF Research Database (Denmark)

    Fowler, D.; Pilegaard, Kim; Sutton, M.A.;

    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, O3, CH4, N2O and particles...

  16. Dark-to-arc transition in field emission dominated atmospheric microdischarges

    International Nuclear Information System (INIS)

    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

  17. Study of X-rays at the atmosphere of the South Atlantic Magnetic Anomaly

    International Nuclear Information System (INIS)

    A study of X-rays at the atmosphere of the South Atlantic Magnetic Anomaly is presented in this work, in which an analysis of all existing balloon measurements carried out at this region has been done. It is concluded that the X-ray flux due to electron precipitation depends strongly on geomagnetic activity, reaching at Sao Jose dos Campos a maximum doward flux of 10-2 photons/cm2.sec.KeV for 4g/cm2 and for the energy range of 30-150KeV. The related flux of precipitating electrons was computed by Monte Carlo method with values of about 500 electrons/cm2.sec and energy espectra of the type e-T/200. This electron flux is shown to represent the main ionization flux for the atmosphere at about 60 Km height. Furthermore, the atmospheric and diffuse components were determined at balloon altitudes (approximately 5g/cm2) of Sao Jose dos campos (λm = 110S) to be of the same order. (author)

  18. Terrestrial atmosphere, water and astrobiology

    OpenAIRE

    Coradini M.; Brack A.

    2010-01-01

    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 bon...

  19. 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...

  20. Particle diffusion in atmospheres of CP stars

    OpenAIRE

    Aret, A.; Sapar, A.

    1998-01-01

    We give concisely the formulae governing diffusion of chemical elements and their isotopes in quiescent stellar atmospheres, due to electrostatic, gravitational and radiation fields and to impacts between particles. Isotope segregation of heavy elements due to light-induced drift is emphasized.

  1. Statistics in Atmospheric Science

    OpenAIRE

    Solow, Andrew R.

    2003-01-01

    This paper reviews the use of statistical methods in atmospheric science. The applications covered include the development, assessment and use of numerical physical models of the atmosphere and more empirical analysis unconnected to physical models.

  2. 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...

  3. 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...

  4. Earth's changeable atmosphere

    Science.gov (United States)

    2016-06-01

    Billions of years ago, high atmospheric greenhouse gas concentrations were vital to life's tenuous foothold on Earth. Despite new constraints, the composition and evolution of Earth's early atmosphere remains hazy.

  5. Atmospheric Lepton Fluxes

    CERN Document Server

    Gaisser, Thomas K

    2014-01-01

    This review of atmospheric muons and neutrinos emphasizes the high energy range relevant for backgrounds to high-energy neutrinos of astrophysical origin. After a brief historical introduction, the main distinguishing features of atmospheric $\

  6. 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,...

  7. 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

  8. 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.

  9. 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...

  10. 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

  11. Intensifying the Atmospheric

    DEFF Research Database (Denmark)

    Liebst, Lasse Suonperä

    2012-01-01

    understanding of atmospheres as aesthetically ‘radiating’ from the surfaces of space, thinks physiognomically, the article argues for a spatial morphological perspective on atmospheres. Thus, post-phenomeno¬logically, it is argued that the atmospheric given is given by the density of pedestrians, which are...

  12. Atmospheric discharges and particle fluxes

    Science.gov (United States)

    Chilingarian, A.; Chilingaryan, S.; Reymers, A.

    2015-07-01

    Fluxes of the electrons, gamma rays, and neutrons observed by particle detectors located on the Earth's surface during thunderstorms originate so-called Thunderstorm Ground Enhancements (TGEs). The relativistic runaway electron avalanches giving rise to TGEs originate in the thundercloud's lower dipole between the main negatively charged region in the middle of the thundercloud and transient lower positively charged region. Acceleration of electrons in the upper dipole between main negative and main positive charge regions leads to initiation of the terrestrial gamma flashes (TGFs) intensive researched during the last two decades by orbiting gamma ray observatories. TGFs are exceptionally intense, submillisecond bursts of electromagnetic radiation directed to the open space from the thunderstorm atmosphere. Unlike visible lightning, TGF beams do not create a hot plasma channel and optical flash; hence, in the literature they got name "dark lightning." We investigate the TGEs development in 1 min and 1 s time series of particle detector count rates. Synchronized time series of the near-surface electric field and lightning occurrences allows interconnecting two atmospheric phenomena. Registration of the Extensive Air Showers allows approaching problems of relation of the lightning occurrences and particle fluxes.

  13. Nonisothermal Pluto atmosphere models

    International Nuclear Information System (INIS)

    The present thermal profile calculation for a Pluto atmosphere model characterized by a high number fraction of CH4 molecules encompasses atmospheric heating by solar UV flux absorption and conductive transport cooling to the surface of Pluto. The stellar occultation curve predicted for an atmosphere of several-microbar surface pressures (which entail the existence of a substantial temperature gradient close to the surface) agrees with observations and implies that the normal and tangential optical depth of the atmosphere is almost negligible. The minimum period for atmospheric methane depletion is calculated to be 30 years. 29 refs

  14. Acoustics in the Martian Atmosphere

    Science.gov (United States)

    Williams, J.-P.

    2000-10-01

    With the advent of the first attempt to deliver an acoustic microphone to the Martian surface aboard the failed Mars Polar Lander, there has been growing interests in the development of acoustic sensors to compliment scientific payloads on future spacecraft. Terrestrial scientist have been very successful in using infrasound (sound at frequencies below human detection, detect and monitor atmospheric phenomena related to weather, tornadoes, mountain waves, microbaroms, ionospheric and auroral disturbances, and meteror/fireballs, as well as anthropogenic sources such as aircraft and nuclear explosions. Sounds on Mars at the audible frequencies (20 Hz to 20 kHz) will be severely attenuated due to viscous relaxation and thermal diffusion (collectively referred to as classical attenuation) which will be much more severe in the colder, less dense Martian atmosphere. Molecular relaxation of carbon dioxide will also contribute to the sound absorption in the lower audible frequencies. Since classical attenuation increases as a function of the frequency squared, at low infrasonic frequencies ( < 10 Hz), classical attenuation becomes less significant and sound absorption in the Martian atmosphere becomes more similar to that of the terrestrial atmosphere for the same frequencies. At these longer wavelengths, geometric spreading will dominate as the source of attenuation as the acoustic energy is spread out over an ever increasing spherical wave front. This implies that infrasound (10 to 0.01 Hz) will be a useful frequency range for future acoustic sensors developed for scientific payloads delivered to the Martian surface.

  15. 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. PMID:20368458

  16. Radiative transfer in the cloudy atmosphere

    OpenAIRE

    Mayer B.

    2009-01-01

    Radiative transfer in clouds is a challenging task, due to their high spatial and temporal variability which is unrivaled by any other atmospheric species. Clouds are among the main modulators of radiation along its path through the Earth’s atmosphere. The cloud feedback is the largest source of uncertainty in current climate model predictions. Cloud observation from satellites, on a global scale, with appropriate temporal and spatial sampling is therefore one of the top aims of current Earth...

  17. Antropogen contamination of the earth atmosphere

    International Nuclear Information System (INIS)

    Among the antropogen contamination sources of the earth atmosphere the total beta activity of rain water, carbon 14 activity according to the annual rings of trees and the krypton 85 activity of the air were determined systematically for several years in Hungary. The data of aerial contamination due to atmospheric nuclear explosions and to the impact of nuclear facilities especially nuclear power plants and fuel reprocessing plants are discussed and demonstrated in graphs. (V.N.) 12 refs.; 7 figs

  18. Impact of Amazonian deforestation on atmospheric chemistry

    OpenAIRE

    Ganzeveld, L.N.; Lelieveld, J.

    2004-01-01

    A single-column chemistry and climate model has been used to study the impact of deforestation in the Amazon Basin on atmospheric chemistry. Over deforested areas, daytime ozone deposition generally decreases strongly except when surface wetness decreases through reduced precipitation, whereas nocturnal soil deposition increases. The isoprene and soil nitric oxide emissions decrease although nitrogen oxide release to the atmosphere increases due to reduced canopy deposition. Deforestation als...

  19. Upper Atmosphere Humidity Measurement with Drycap Sensor

    OpenAIRE

    Lehtola, Terhi Johanna

    2014-01-01

    Atmospheric water vapor is a significant greenhouse gas. To gain proper understanding of the impact of water vapor on the climate, atmospheric water vapor profiles should be measured with high precision and accuracy. Due to challenging environmental conditions including extremely low temperatures and humidity concentrations, few research grade instruments are capable of measuring humidity accurately in upper troposphere and stratosphere. Laborious utilization or inadequate resolution of the e...

  20. The Radiometer Atmospheric Cubesat Experiment

    Science.gov (United States)

    Lim, B.; Bryk, M.; Clark, J.; Donahue, K.; Ellyin, R.; Misra, S.; Romero-Wolf, A.; Statham, S.; Steinkraus, J.; Lightsey, E. G.; Fear, A.; Francis, P.; Kjellberg, H.; McDonald, K.

    2014-12-01

    The Jet Propulsion Laboratory (JPL) has been developing the Radiometer Atmospheric CubeSat Experiment (RACE) since 2012, which consists of a water vapor radiometer integrated on a 3U CubeSat platform. RACE will measure 2 channels of the 183 GHz water vapor line, and will be used to validate new low noise amplifier (LNA) technology and a novel amplifier based internal calibration subsystem. The 3U spacecraft is provided by the University of Texas at Austin's Satellite Design Laboratory. RACE will advance the technology readiness level (TRL) of the 183 GHz receiver subsystem from TRL 4 to TRL 6 and a CubeSat 183 GHz radiometer system from TRL 4 to TRL 7. Measurements at 183 GHz are used to retrieve integrated products and vertical profiles of water vapor. Current full scale satellite missions that can utilize the technology include AMSU, ATMS, SSMIS and Megha-Tropiques. The LNAs are designed at JPL, based on a 35 nm indium phosphide (InP) high-electron-mobility transistors (HEMT) technology developed by Northrop Grumman. The resulting single chip LNAs require only 25 mW of power. Current pre-launch instrument performance specifications include an RF gain of over 30 dB and a room noise figure of 5dB. If a coupler based calibration system is shown to be sufficient, future receiver systems will have noise figures < 4 dB. The gain and noise figure variation over temperature is approximately 0.55 dB/K. The NEDT of the system is < 1K, and on orbit performance is expected to improve due to the thermal environment. The current system is configured for direct detection to reduce power consumption by eliminating the need for a local oscillator. A 2012 NASA CubeSat Launch Initiative (CSLI) selection, RACE is manifested for launch on the Orbital 3 (Orb-3) mission scheduled for October 2014. RACE will be deployed from the International Space Station (ISS) by NanoRacks.

  1. 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.

  2. 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.

  3. Onychomycosis Due to Nondermatophytic Molds

    OpenAIRE

    Hwang, Sung Min; Suh, Moo Kyu; Ha, Gyoung Yim

    2012-01-01

    Background Although there have been many studies about onychomycosis due to nondermatophytic molds (NDM), few studies about etiologic agents including NDM in onychomycosis have been reported in Korea. Objective: This study investigated onychomycosis due to NDM in the Gyeongju area of Korea. Objective This study investigated onychomycosis due to NDM in the Gyeongju area of Korea. Methods In the 10-year period from 1999~2009, we reviewed 59 patients with onychomycosis due to NDM. The etiologic ...

  4. The atmospheric extinction of light

    CERN Document Server

    Hughes, Stephen W; Powell, Sean; Carroll, Joshua

    2015-01-01

    An experiment is described that enables students to understand the properties of atmospheric extinction due to Rayleigh scattering. The experiment requires the use of red, green and blue lasers attached to a travelling microscope or similar device. The laser beams are passed through an artificial atmosphere, made from milky water, at varying depths, before impinging on either a light meter or a photodiode integral to a Picotech Dr. DAQ ADC. A plot of measured spectral intensity verses depth reveals the contribution Rayleigh scattering has to the extinction coefficient. For the experiment with the light meter, the extinction coefficients for red, green and blue light in the milky sample of water were 0.27, 0.36 and 0.47 cm^-1 respectively and 0.032, 0.037 and 0.092 cm^-1 for the Picotech Dr. DAQ ADC.

  5. The atmospheric extinction of light

    Science.gov (United States)

    Hughes, Stephen W.; Cowley, Michael; Powell, Sean; Carroll, Joshua

    2016-01-01

    An experiment is described that enables students to understand the properties of atmospheric extinction due to Rayleigh scattering. The experiment requires the use of red, green and blue lasers attached to a travelling microscope or similar device. The laser beams are passed through an artificial atmosphere, made from milky water, at varying depths, before impinging on either a light meter or a photodiode integral to a Picotech Dr. DAQ ADC. A plot of measured spectral intensity verses depth reveals the contribution Rayleigh scattering has to the extinction coefficient. For the experiment with the light meter, the extinction coefficients for red, green and blue light in the milky sample of water were 0.27, 0.36 and 0.47 cm-1 respectively and 0.032, 0.037 and 0.092 cm-1 for the Picotech Dr. DAQ ADC.

  6. Atmospheric Scintillation in Astronomical Photometry

    CERN Document Server

    Osborn, J; Dhillon, V S; Wilson, R W

    2015-01-01

    Scintillation noise due to the Earth's turbulent atmosphere can be a dominant noise source in high-precision astronomical photometry when observing bright targets from the ground. Here we describe the phenomenon of scintillation from its physical origins to its effect on photometry. We show that Young's (1967) scintillation-noise approximation used by many astronomers tends to underestimate the median scintillation noise at several major observatories around the world. We show that using median atmospheric optical turbulence profiles, which are now available for most sites, provides a better estimate of the expected scintillation noise and that real-time turbulence profiles can be used to precisely characterise the scintillation noise component of contemporaneous photometric measurements. This will enable a better understanding and calibration of photometric noise sources and the effectiveness of scintillation correction techniques. We also provide new equations for calculating scintillation noise, including ...

  7. Contribution of proton and electron precipitation to the observed electron concentration in October-November 2003 and September 2005

    Energy Technology Data Exchange (ETDEWEB)

    Verronen, P.T.; Andersson, M.E.; Kauristie, K.; Palmroth, M. [Finnish Meteorological Institute, Helsinki (Finland). Earth Observation; Kero, A. [Oulu Univ., Sodankylae (Finland). Sodankylae Geophysical Observatory; Enell, C.F. [EISCAT Scientific Association, Kiruna (Sweden); Wissing, J.M. [Osnabrueck Univ. (Germany). Inst. of Environmental Systems Research; Talaat, E.R. [Johns Hopkins Univ., Laurel, MD (United States). Applied Physics Lab.; Sarris, T.E. [Democritus Univ. of Thrace, Xanthi (Greece). Space Research Lab.; Armandillo, E. [European Space Agency, Nordwijk (Netherlands). ESTEC

    2015-01-01

    Understanding the altitude distribution of particle precipitation forcing is vital for the assessment of its atmospheric and climate impacts. However, the proportion of electron and proton forcing around the mesopause region during solar proton events is not always clear due to uncertainties in satellite-based flux observations. Here we use electron concentration observations of the European Incoherent Scatter Scientific Association (EISCAT) incoherent scatter radars located at Tromsoe (69.58 N, 19.23 E) to investigate the contribution of proton and electron precipitation to the changes taking place during two solar proton events. The EISCAT measurements are compared to the results from the SodankylaeIon and Neutral Chemistry Model (SIC). The proton ionization rates are calculated by two different methods - a simple energy deposition calculation and the Atmospheric Ionization Model Osnabrueck (AIMOS v1.2), the latter providing also the electron ionization rates. Our results show that in general the combination of AIMOS and SIC is able to reproduce the observed electron concentration within 50% when both electron and proton forcing is included. Electron contribution is dominant above 90 km, and can contribute significantly also in the upper mesosphere especially during low or moderate proton forcing. In the case of strong proton forcing, the AIMOS electron ionization rates seem to suffer from proton contamination of satellite-based flux data. This leads to overestimation of modelled electron concentrations by up to 90% between 75-90 km and up to 100-150% at 70-75 km. Above 90 km, the model bias varies significantly between the events. Although we cannot completely rule out EISCAT data issues, the difference is most likely a result of the spatio-temporal fine structure of electron precipitation during individual events that cannot be fully captured by sparse in situ flux (point) measurements, nor by the statistical AIMOS model which is based upon these observations

  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. Dosimetria em folículos tireoidianos devido aos elétrons de baixa energia do iodo usando o método Monte Carlo Dosimetry in thyroid follicles due to low-energy electrons of iodine using the Monte Carlo method

    Directory of Open Access Journals (Sweden)

    Laélia Campos

    2008-12-01

    Full Text Available OBJETIVO: Avaliar a dose absorvida em folículos tireoidianos devido aos elétrons de baixa energia, como os elétrons Auger e os de conversão interna, além das partículas beta, para os radioisótopos de iodo (131I, 132I, 133I, 134I e 135I usando o método Monte Carlo. MATERIAIS E MÉTODOS: O cálculo da dose foi feito ao nível folicular, simulando elétrons Auger, conversão interna e partículas beta, com o código MCNP4C. Os folículos (colóide e células foliculares foram modelados como esferas, com diâmetros do colóide variando de 30 a 500 mm. A densidade considerada para os folículos foi a da água (1,0 g.cm-³. RESULTADOS: Considerando partículas de baixa energia, o percentual de contribuição do 131I na dose total absorvida pelo colóide é de aproximadamente 25%, enquanto os isótopos de meia-vida física curta apresentaram contribuição de 75%. Para as células foliculares, esse percentual é ainda maior, chegando a 87% para os iodos de meia-vida curta e 13% para o 131I. CONCLUSÃO: Com base nos resultados obtidos, pode-se mostrar a importância de se considerar partículas de baixa energia na contribuição para a dose total absorvida ao nível folicular (colóide e células foliculares devido aos radioisótopos de iodo (131I, 132I, 133I, 134I e 135I.OBJECTIVE: To evaluate the absorbed dose in thyroid follicles due to low-energy electrons such as Auger and internal conversion electrons, besides beta particles, for iodine radioisotopes (131I, 132I, 133I, 134I and 135I utilizing the Monte Carlo method. MATERIALS AND METHODS: The dose calculation was performed at follicular level, simulating Auger, internal conversion electrons and beta particles, with the MCNP4C code. The follicles (colloid and follicular cells were modeled as spheres with colloid diameter ranging from 30 to 500 mm, and with the same density of water (1.0 g.cm-³. RESULTS: Considering low-energy particles, the contribution of 131I for total absorbed dose to

  10. Pluto's atmosphere near perihelion

    International Nuclear Information System (INIS)

    A recent stellar occultation has confirmed predictions that Pluto has an atmosphere which is sufficiently thick to uniformly envelope the planet and to extend far above the surface. Pluto's atmosphere consists of methane and perhaps other volatile gases at temperatures below their freezing points; it should regulate the surface temperature of its volatile ices to a globally uniform value. As Pluto approaches and passes through perihelion, a seasonal maximum in the atmospheric bulk and a corresponding minimum in the exposed volatile ice abundance is expected to occur. The lag in maximum atmospheric bulk relative to perihelion will be diagnostic of the surface thermal properties. An estimate of Pluto's atmospheric bulk may result if a global darkening (resulting from the disappearance of the seasonally deposited frosts) occurs before the time of maximum atmospheric bulk. The ice deposited shortly after perihelion may be diagnostic of the composition of Pluto's volatile reservoir

  11. 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...

  12. Fair weather atmospheric electricity

    International Nuclear Information System (INIS)

    Not long after Franklin's iconic studies, an atmospheric electric field was discovered in 'fair weather' regions, well away from thunderstorms. The origin of the fair weather field was sought by Lord Kelvin, through development of electrostatic instrumentation and early data logging techniques, but was ultimately explained through the global circuit model of C.T.R. Wilson. In Wilson's model, charge exchanged by disturbed weather electrifies the ionosphere, and returns via a small vertical current density in fair weather regions. New insights into the relevance of fair weather atmospheric electricity to terrestrial and planetary atmospheres are now emerging. For example, there is a possible role of the global circuit current density in atmospheric processes, such as cloud formation. Beyond natural atmospheric processes, a novel practical application is the use of early atmospheric electrostatic investigations to provide quantitative information on past urban air pollution.

  13. Photochemistry in planetary atmospheres

    Science.gov (United States)

    Levine, J. S.; Graedel, T. E.

    1981-01-01

    Widely varying paths of evolutionary history, atmospheric processes, solar fluxes, and temperatures have produced vastly different planetary atmospheres. The similarities and differences between the earth atmosphere and those of the terrestrial planets (Venus and Mars) and of the Jovian planets are discussed in detail; consideration is also given to the photochemistry of Saturn, Uranus, Pluto, Neptune, Titan, and Triton. Changes in the earth's ancient atmosphere are described, and problems of interest in the earth's present troposphere are discussed, including the down wind effect, plume interactions, aerosol nucleation and growth, acid rain, and the fate of terpenes. Temperature fluctuations in the four principal layers of the earth's atmosphere, predicted decreases in the ozone concentration as a function of time, and spectra of particles in the earth's upper atmosphere are also presented. Finally, the vertical structure of the Venus cloud system and the thermal structure of the Jovian planets are shown graphically.

  14. Electronic energy states

    Science.gov (United States)

    1976-01-01

    One-electron wave functions are reviewed and approximate solutions of two-electron systems are given in terms of these one-electron functions. The symmetry effects associated with electron spin are reviewed and the effects of electron exchange on energy levels of the two-electron system are given. The coupling of electronic orbital and spin angular momentum is considered next and the Lande interval rule for Russell-Saunders or LS coupling is derived. The configurations possible for various multi-electron LS couplings are enumerated (examples from the first two rows of the periodic table are given), and the meaning of the spectroscopic nomenclature is discussed, particularly with respect to the degeneracies of the electron states involved. Next the nomenclature, symmetries, and degeneracies for electron states of diatomic molecules are discussed, and some examples for N2, O2, and NO are presented. The electronic partition functions and derivative thermodynamic properties are expressed in terms of these energies and degeneracies, and examples are given for some of the simple gas species encountered in the earth's atmosphere.

  15. Experiment for Investigation of Atmosphere-Magnetosphere Relationship at Mars

    Science.gov (United States)

    Vaisberg, O. L.; Koynash, G.; Shestakov, A.; Roman, Z.; Moiseenko, D.; Kirillov, A. S.; Chernouss, S.; Moiseev, P.; Shefov, N.; Semenov, A.; Rodionov, I.; Sosonkin, M.; Ivanov, Y.; Sinyavsky, I.; Sigernes, F.; Berthellier, J.; Leblanc, F.

    2013-12-01

    also on content of the atoms and molecules with provide 20-25 eV photoelectrons due to their ionization by solar 30.4 nm emission. Therefore the measurements of He emission will provide information on excitation mechanisms and altitude composition of Martian upper atmosphere. Observations of escaping ions through the flanks of the tail will be performed with spectrophotometer of emissions of O+, CO+, O2+ or CO2+ ions of that scatter solar light. With observations along the tail it is possible to use increased optical thickness and study the acceleration of these ions along the tail. This suite of 4 instruments uses one electronics box. Total estimated mass is about 1.7 kg. Instruments can be installed on satellite, rower or stationary platform. Satellite provides better coverage while rower or stationary platform gives opportunity to increase the signal to noise ratio through longer accumulation of the signal and register temporal variations of intensity, Instruments can be used for investigation of other planets, specifically the Venus. Prototypes of 4 instruments exist.

  16. 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......, in order to encompass dynamic atmospheres as intertwined, constantly shifting negotiations between the rhythms of the environment and of the body. The contribution of this paper is to unravel these negotiations of diverse rhythms, in order to approach dynamic atmospheres from an operational...

  17. 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...

  18. Environmental radon: solid earth-atmosphere transference

    International Nuclear Information System (INIS)

    The radon anomalies ant its descendants related with geophysical events are studied generally for to understand the involved mechanisms in the underground geochemistry. These anomalies were observed as a radioactivity level argumentation in the systems studied provoking a radioactivity transference from land toward human environment. In this work is presented an analysis of the contribution at local radioactivity level due to volcanic eruptions that they provoke a transference appreciable but intermittent and located of Radon to atmosphere and of that one due to soil-atmosphere transference that it occurs in continuous way in continent that it varies as function of meteorologic and geologic conditions. (Author)

  19. Detection of Callisto's oxygen atmosphere with the Hubble Space Telescope

    Science.gov (United States)

    Cunningham, Nathaniel J.; Spencer, John R.; Feldman, Paul D.; Strobel, Darrell F.; France, Kevin; Osterman, Steven N.

    2015-07-01

    We report the result of a search for evidence of an O2-dominated atmosphere on Callisto, using the high far-ultraviolet sensitivity of the Hubble Space Telescope Cosmic Origins Spectrograph (COS). Observations of Callisto's leading/Jupiter-facing hemisphere show, for the first time, variable-strength atomic oxygen (O I) emissions with brightness up to 4.7 ± 0.7 Rayleighs for the O I 1304 Å triplet and 1.9 ± 0.4 Rayleighs for the O I 1356 Å doublet, averaged over the 2.5 arcsec. diameter COS aperture. Because the observations were made in Earth's shadow, and are brighter than expected emission from nighttime geocoronal airglow or other plausible sources, we are confident that they originate from Callisto or its immediate vicinity. In addition, COS's limited (∼1 arcsec) spatial resolution implies a 2σ detection of excess 1356 Å emission concentrated on the disk of Callisto itself, with brightness 3.2 ± 1.6 Rayleighs. The (O I 1356 Å)/(O I 1304 Å) emission ratio from Callisto's disk favors dissociative excitation of O2, suggesting that O2 is the dominant atmospheric component rather than other possible oxygen-bearing alternatives. Photoelectrons, rather than magnetospheric electrons, are the most likely source of the dissociative excitation. This detection yields an O2 column density of ∼4 × 1015 cm-2 on the leading/Jupiter facing hemisphere, which implies that Callisto's atmosphere is collisional and is the fourth-densest satellite atmosphere in the Solar System, in addition to being the second-densest O2-rich collisional atmosphere in the Solar System, after Earth. Longitudinal variations in published densities of ionospheric electrons suggest that O2 densities in Callisto's trailing hemisphere, which we did not observe, may be an order of magnitude greater. The aperture-filling emissions imply that there is also an extended corona of predominantly O I 1304 Å emission around Callisto, with observed strength of 1-4 Rayleighs, likely due to solar

  20. Measurement of atmospheric neutrino oscillations and matter effects with PINGU

    International Nuclear Information System (INIS)

    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.