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Sample records for bernstein wave emission

  1. Thermal Electron Bernstein Wave Emission Measurements on NST

    Czech Academy of Sciences Publication Activity Database

    Diem, S.J.; Taylor, G.; Efthimion, P.; LeBlanc, B.P.; Philips, C.K.; Caughman, J.; Wilgen, J.B.; Harvey, R.W.; Preinhaelter, Josef; Urban, Jakub

    2006-01-01

    Roč. 51, č. 7 (2006), s. 134. ISSN 0003-0503. [Annual Meeting of the Division of Plasma Physics/48th./. Philadelphia, Pennsylvania, 30.10.2006-3.11.2006] Institutional research plan: CEZ:AV0Z20430508 Keywords : Conversion * Emission * Tokamaks * Electron Bernstein waves * Simulation * MAST * NSTX Subject RIV: BL - Plasma and Gas Discharge Physics http://www.aps.org/meet/DPP06/baps/all_DPP06.pdf

  2. Electron Bernstein Wave Heating and Emission in the TCV Tokamak

    OpenAIRE

    Anja, Mueck; Yann, Camenen; Stefano, Coda; Loïc, Curchod; Timothy P., Goodman; Heinrich P., Laqua; Antoine, Pochelon; Laurie, Porte; Victor S., Udintsev; Francesco, Volpe; Team, TCV

    2007-01-01

    Electron cyclotron resonance heating (ECRH) of high-density tokamak plasmas is limited because of reflections of the waves at so-called wave cutoffs. Electron Bernstein wave (EBW) heating (EBWH) via a double mode conversion process from ordinary (O)-mode, launched from the low field side, to extraordinary (X)-mode and finally to Bernstein (B)-mode offers the possibility of overcoming these density limits. In this paper, the O-X mode conversion dependence on the microwave injection angle is de...

  3. Electron cyclotron-electron Bernstein wave emission diagnostics for the COMPASS tokamak

    International Nuclear Information System (INIS)

    The COMPASS tokamak recently started operation at the Institute of Plasma Physics AS CR, v.v.i., Prague. A new 16-channel radiometer, operating alternatively in three frequency bands, has been designed and constructed. The system is prepared for detection of normal electron cyclotron emission (O1 or X2) or oblique electron Bernstein wave emission. The end-to-end calibration method includes all components that influence the antenna radiation pattern. A steady recalibration is possible using a noise generator connected to the radiometer input through a fast waveguide PIN-switch. Measurements of the antenna radiation characteristics (2D electric field) were performed in free space as well as in the tokamak chamber, showing the degradation effect of structures on the Gaussian beam shape. First plasma radiation temperature measurements from low-field circular plasmas are available.

  4. Electron Bernstein Wave Studies: Current Drive; Emission and Absorption with Nonthermal Distributions; Delta-F Particle in Cell Simulations.

    Czech Academy of Sciences Publication Activity Database

    Harvey, R.W.; Cary, J.R.; Taylor, G.; Barnes, D.C.; Bigelow, T.S.; Coda, S.; Carlsson, J.; Caughman, J.B.; Carter, M.D.; Diem, S.; Efthimion, P.C.; Ellis, R.A.; Ershov, N.M.; Fonck, R.J.; Fredd, E.; Gartska, G.D.; Hosea, J.; Jaeger, F.; LeBlanck, B.; Lewicki, B.T.; Phillips, C.K.; Preinhaelter, Josef; Ram, A.K.; Rasmussen, D.A.; Smirnov, A.P.; Urban, Jakub; Wilgen, J.B.; Wilson, J.R.; Xiang, N.

    Čína: IAEA, 2006, TH/P6-11. [IAEA Fusion Energy Conference/21st./. Chengdu, China (CN), 16.10.2006-21.10.2006] Institutional research plan: CEZ:AV0Z20430508 Keywords : Conversion * Emission * Tokamaks * Electron Bernstein waves * Simulation * NSTX * Particle in cell Subject RIV: BL - Plasma and Gas Discharge Physics http://www-pub.iaea.org/MTCD/Meetings/FEC2006/th_p6-11.pdf

  5. Design and testing of an electron Bernstein wave emission radiometer for the TJ-II Stellarator

    International Nuclear Information System (INIS)

    Efficient Electron Bernstein wave (EBW) mode conversion is important for heating dense plasmas in TJ-II. The O-X-B mode conversion scenario is being considered for heating plasmas with densities over 1,3 x 1019 m-3, which will be very interesting to study high-density physics and for heating NBI plasmas. Measurement of the thermal EBW emission from the plasma allows the EBW mode conversion efficiency to be determined, and also has the potential to offer a diagnostic for measuring electron temperature profile evolution in overdense plasmas. A dual-polarized quad-ridged broadband horn with a focusing lens will be used to measure the EBW emission at 28 GHz on TJ-II. A focused beam is needed to achieve efficient coupling at the mode conversion layer. Emission from the plasma is reflected from a steerable internal mirror, propagates through a glass lens, and is focused on the horn. The field pattern from the horn-lens combination has been measured as a function of horn-lens spacing and lens focal length with a 3-D scanning system in an effort to minimize the beam waist at the plasma edge. Beam waist sizes have been measured at distances of up to 80 cm from the lens. Details of the experimental results and future plans will be presented. [Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under contract DE-AC05-00OR22725. A part of this work is performed under support of Spanish 'Subdireccion General de Proyectos de Investigacion, Ministerio de Educacion y Ciencia' with reference ENE2004-06957]. (author)

  6. Mode-converted electron Bernstein wave emission research on CDX-U and NSTX

    International Nuclear Information System (INIS)

    Electron Bernstein waves (EBWs) may enable electron temperature profile measurements and local electron heating and current drive in high β overdense (ωpe/ωce>>1) plasmas. Significant results are presented from the measurement of X-mode radiation, converted from EBWs observed normal to the magnetic field on the mid-plane of overdense plasmas in CDX-U and NSTX. A radially scannable, in-vessel, quad-ridged antenna and Langmuir probe array on CDX-U studied EBW to X-mode conversion. A local limiter optimized the conversion efficiency by modifying the density scale length at the mode conversion layer. The fundamental EBW conversion efficiency increased, by an order of magnitude, to ∼100% when the local limiter and antenna were inserted near the conversion layer. This technique can be extended to large, high temperature devices. Another significant observation was that the EBW emission source was localized near the electron cyclotron resonance. As a result, mode-converted EBW radiometry has measured radial transport in CDX-U. In addition, a threefold increase in conversion efficiency was observed at the L to H transition in NSTX. Measured conversion efficiency agreed well with theoretical predictions. EBW ray tracing and bounce-averaged Fokker-Planck codes are being used to model EBW heating and current drive scenarios for NSTX equilibria with β up to 40%. So far, results show that it is possible to drive localized currents on the high field side of the magnetic axis in NSTX at β ∼ 12% with current drive efficiency which compares favorably with ECCD. (authors)

  7. Measurement of The Magnetic Field in a Spherical Torus Plasma via Electron Bernstein Wave Emission Harmonic Overlap Measurement of The Magnetic Field in a Spherical Torus Plasma via Electron Bernstein Wave Emission Harmonic Overlap

    Energy Technology Data Exchange (ETDEWEB)

    B. Jones; G. Taylor; P.C. Efthimion; T. Munsat

    2004-01-28

    Measurement of the magnetic field in a spherical torus by observation of harmonic overlap frequencies in the electron Bernstein wave (EBW) spectrum has been previously suggested [V.F. Shevchenko, Plasma Phys. Reports 26 (2000) 1000]. EBW mode conversion to X-mode radiation has been studied in the Current Drive Experiment-Upgrade spherical torus, [T. Jones, Ph.D. thesis, Princeton University, 1995] with emission measured at blackbody levels [B. Jones et al., Phys. Rev. Lett. 90 (2003) article no. 165001]. Sharp transitions in the thermally emitted EBW spectrum have been observed for the first two harmonic overlaps. These transition frequencies are determined by the magnetic field and electron density at the mode conversion layer in accordance with hot-plasma wave theory. Prospects of extending this measurement to higher harmonics, necessary in order to determine the magnetic field profile, and high beta equilibria are discussed for this proposed magnetic field diagnostic.

  8. Ion Bernstein wave heating research

    International Nuclear Information System (INIS)

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW's low phase velocity (ω/kperpendicular ∼ VTi much-lt Vα) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion α-particles. In addition, the property of IBW's that kperpendicular ρi ∼ 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW's can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research

  9. Observations of Obliquely Propagating Electron Bernstein Waves

    DEFF Research Database (Denmark)

    Armstrong, R. J.; Juul Rasmussen, Jens; Stenzel, R. L.;

    1981-01-01

    Plane electron Bernstein waves propagating obliquely to the magnetic field are investigated. The waves are excited by a plane grid antenna in a large volume magnetoplasma. The observations compare favorably with the predictions of the linear dispersion relation.......Plane electron Bernstein waves propagating obliquely to the magnetic field are investigated. The waves are excited by a plane grid antenna in a large volume magnetoplasma. The observations compare favorably with the predictions of the linear dispersion relation....

  10. Enhancement of mode-converted electron Bernstein wave emission during National Spherical Torus Experiment H-mode plasmas

    International Nuclear Information System (INIS)

    A sudden, threefold increase in emission from fundamental electrostatic electron Bernstein waves (EBW) which mode convert and tunnel to the electromagnetic X-mode has been observed during high energy and particle confinement (H-mode) transitions in the National Spherical Torus Experiment (NSTX) plasma [M. Ono, S. Kaye, M. Peng et al., in Proceedings of the 17th IAEA Fusion Energy Conference (IAEA, Vienna, Austria, 1999), Vol. 3, p. 1135]. The mode-converted EBW emission viewed normal to the magnetic field on the plasma midplane increases when the density profile steepens in the vicinity of the mode conversion layer, which is located in the plasma scrape off. The measured conversion efficiency during the H-mode is consistent with the calculated EBW to X-mode conversion efficiency derived using edge density data. Calculations indicate that there may also be a small residual contribution to the measured X-mode electromagnetic radiation from polarization-scrambled, O-mode emission, converted from EBWs

  11. Relativistic Bernstein waves in a degenerate plasma

    International Nuclear Information System (INIS)

    Bernstein mode for a relativistic degenerate electron plasma is investigated. Using relativistic Vlasov-Maxwell equations, a general expression for the conductivity tensor is derived and then employing Fermi-Dirac distribution function a generalized dispersion relation for the Bernstein mode is obtained. Two limiting cases, i.e., non-relativistic and ultra-relativistic are discussed. The dispersion relations obtained are also graphically presented for some specific values of the parameters depicting how the propagation characteristics of Bernstein waves as well as the Upper Hybrid oscillations are modified with the increase in plasma number density.

  12. Te(R, t) measurements using electron Bernstein wave thermal emission on NSTX

    Czech Academy of Sciences Publication Activity Database

    Diem, S.J.; Taylor, G.; Efthimion, P.C.; LeBlanc, P.C.; Carter, M.; Caughman, J.; Wilgen, J.B.; Harvey, R.W.; Preinhaelter, Josef; Urban, Jakub

    2006-01-01

    Roč. 77, č. 10 (2006), 10E919, 1-10E919,4. ISSN 0034-6748. [Topical Conference on High-Temperature Plasma Diagnostics/16th./. Williamsburg, Virginia, 7.5.2006-11.5.2006] Institutional research plan: CEZ:AV0Z20430508 Keywords : Overdense plasma * Conversion * Emission * Excitation * Tokamaks * Diagnostics Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.541, year: 2006 http://link.aip.org/link/?RSI/77/10E919

  13. Electron Bernstein Wave (EBW) Physics In NSTX and PEGASUS

    Czech Academy of Sciences Publication Activity Database

    Taylor, G.; Caughman, J.B.; Carter, M.D.; Diem, S.; Efthimion, P.C.; Harvey, R.W.; Preinhaelter, Josef; Wilgen, J.B.; Bigelow, T.S.; Ellis, R.A.; Ershov, N.M.; Fonck, R.J.; Fredd, E.; Gartska, G.D.; Hosea, J.; Jaeger, F.; LeBlanck, B.; Lewicki, B.T.; Philips, C.K.; Ram, A.K.; Rasmussen, D.A.; Smirnov, A.P.; Urban, Jakub; Wilson, J.R.

    USA: The University of Texas at Austin, 2006, s. 1-24. [Innovative Confinement Concepts Workshop. Austin,Texas (US), 13.02.2006-16.02.2006] Institutional research plan: CEZ:AV0Z20430508 Keywords : Conversion * Emission * Tokamaks * Electron Bernstein waves * Simulation * MAST * NSTX Subject RIV: BL - Plasma and Gas Discharge Physics http://icc2006.ph.utexas.edu/proceedings.php http://icc2006.ph.utexas.edu/uploads/29/icc06_taylor_ebw_022706.pdf

  14. X-ray Imaging and preliminary studies of the X-ray self-emission from an innovative plasma-trap based on the Bernstein waves heating mechanism

    Science.gov (United States)

    Caliri, C.; Romano, F. P.; Mascali, D.; Gammino, S.; Musumarra, A.; Castro, G.; Celona, L.; Neri, L.; Altana, C.

    2013-10-01

    Electron Cyclotron Resonance Ion Sources (ECRIS) are based on ECR heated plasmas emitting high fluxes of X-rays. Here we illustrate a pilot study of the X-ray emission from a compact plasma-trap in which an off-resonance microwave-plasma interaction has been attempted, highlighting a possible Bernstein-Waves based heating mechanism. EBWs-heating is obtained via the inner plasma EM-to-ES wave conversion and enables to reach densities much larger than the cut-off ones. At LNS-INFN, an innovative diagnostic technique based on the design of a Pinhole Camera (PHC) coupled to a CCD device for X-ray Imaging of the plasma (XRI) has been developed, in order to integrate X-ray traditional diagnostics (XRS). The complementary use of electrostatic probes measurements and X-ray diagnostics enabled us to gain knowledge about the high energy electrons density and temperature and about the spatial structure of the source. The combination of the experimental data with appropriate modeling of the plasma-source allowed to estimate the X-ray emission intensity in different energy domains (ranging from EUV up to Hard X-rays). The use of ECRIS as X-ray source for multidisciplinary applications, is now a concrete perspective due to the intense fluxes produced by the new plasma heating mechanism.

  15. Generation of magnetospheric radiation by decay of Bernstein waves

    International Nuclear Information System (INIS)

    Recent observations show that extremely narrow emission lines are present in the spectrum of the terrestrial myriametric radiation, which on the basis of earlier observations has been characterized as nonthermal contiunuum radiation. The occurance of these monochromatic emissions is not predicted by previoiusly published theories for the generation of the radiaiton. A linear instability, exciting low frequency electrostatic turbulence, is required by theories invoking a nonlinear coalescence to produce the radiation, but there are no conclusive observations associating low frequency electrostatic waves with the sources of myriametric radiation. In this study, the possibility that the radiation is produced by a nonlinear decay of electrostatic Bernstein waves with frequency near the upper hybrid frequency is considered. This mechanism can explain the narrow spectral lines, and does not require a linear instability at low frequencies. (Author)

  16. Harmonic launching of ion Bernstein waves via mode transformation

    International Nuclear Information System (INIS)

    Ion Bernstein wave excitation and propagation via finite ion-Larmor-radium mode-transformation are investigated theoretically and experimentally. It is shown that in the ion cyclotron range of frequencies omega less than or equal to 4Ω/sub i/, with modest ion temperatures (T/sub i/ less than or equal to 10 eV), the finite-Larmor-radius effect removes the wave singularity at lower-hybrid resonance layer, enabling an externally initiated electron plasma wave to transform continuously into an ion Bernstein wave. In an ACT-1 hydrogen plasma (T/sub e/ approx. = 2.5 eV, T/sub i/ less than or equal to 2.0 eV), externally excited ion Bernstein waves have been observed for omega less than or equal to 2Ω/sub i/ as well as for omega less than or equal to 3Ω/sub i/. The finite ion-Larmor-radius mode transformation process resulting in strong ion Bernstein wave excitation has been experimentally verified. Detailed measurements of the wave dispersion relation and of the wave-packet trajectory show excellent agreement with theory. The dependence of the excited ion Bernstein wave on the antenna phasing, the plasma density, and on the neutral pressure (T/sub i/) is also investigated

  17. Electron-Bernstein Waves in Inhomogeneous Magnetic Fields

    DEFF Research Database (Denmark)

    Armstrong, R. J.; Frederiksen, Å.; Pécseli, Hans;

    1984-01-01

    The propagation of small amplitude electron-Bernstein waves in different inhomogeneous magnetic field geometries is investigated experimentally. Wave propagation towards both cut-offs and resonances are considered. The experimental results are supported by a numerical ray-tracing analysis. Spatial...... enhancements of the wave amplitude are interpreted as a result of caustic formation....

  18. Ion Bernstein waves in the magnetic reconnection region

    Science.gov (United States)

    Narita, Y.; Nakamura, R.; Baumjohann, W.; Glassmeier, K.-H.; Motschmann, U.; Comişel, H.

    2016-01-01

    Four-dimensional energy spectra and a diagram for dispersion relations are determined for the first time in a magnetic reconnection region in the magnetotail using data from four-spacecraft measurements by the Cluster mission on a spatial scale of 200 km, about 0.1 ion inertial lengths. The energy spectra are anisotropic with an extension in the perpendicular direction and axially asymmetric with respect to the mean magnetic field. The dispersion diagram in the plasma rest frame is in reasonably good agreement with the ion Bernstein waves at the second and higher harmonics of the proton gyrofrequency. Perpendicular-propagating ion Bernstein waves likely exist in an outflow region of magnetic reconnection, which may contribute to bifurcation of the current sheet in the outflow region.

  19. Electron Bernstein Wave Research on NSTX and PEGASUS

    Czech Academy of Sciences Publication Activity Database

    Diem, S.J.; Taylor, G.; Caughman, J.; Bigelow, T.S.; Garstka, G.D.; Harvey, R.W.; LeBlanc, B.P.; Preinhaelter, Josef; Sabbagh, S.A.; Urban, Jakub; Wilgen, J.

    Vol. 933. Melville: -, 2007 - (Ryan, P.; Rasmussen, D.), s. 331-334 ISBN 978-0-7354-0444-1. ISSN 0094-243X. [Topical Conference on Radio Frequency Power in Plasmas/17th./. Clearwater (US), 07.05.2007-09.05.2007] Institutional research plan: CEZ:AV0Z20430508 Keywords : Conversion * Cyclotron Heating * Tokamaks * Electron Bernstein waves Subject RIV: BL - Plasma and Gas Discharge Physics

  20. Ion-Bernstein wave mode conversion in hot tokamak plasmas

    International Nuclear Information System (INIS)

    Mode conversion at the second harmonic cyclotron resonance is studied in a toroidal plasma, showing how the ion-Bernstein wave can dramatically affect the power profile and partition among the species. The results obtained with the gyrokinetic toroidal PENN code in particular suggest that off-axis electron and second harmonic core ion heating should become important when the temperatures in JET reach 10 keV. (author) 1 fig., 11 refs

  1. Electron Bernstein Wave Research on NSTX and PEGASUS

    Science.gov (United States)

    Diem, S. J.; Taylor, G.; Caughman, J. B.; Bigelow, T.; Garstka, G. D.; Harvey, R. W.; LeBlanc, B. P.; Preinhaelter, J.; Sabbagh, S. A.; Urban, J.; Wilgen, J. B.

    2007-09-01

    Spherical tokamaks (STs) routinely operate in the overdense regime (ωpe≫ωce), prohibiting the use of standard ECCD and ECRH. However, the electrostatic electron Bernstein wave (EBW) can propagate in the overdense regime and is strongly absorbed and emitted at the electron cyclotron resonances. As such, EBWs offer the potential for local electron temperature measurements and local electron heating and current drive. A critical challenge for these applications is to establish efficient coupling between the EBWs and electromagnetic waves outside the cutoff layer. Two STs in the U.S., the National Spherical Tokamak Experiment (NSTX, at Princeton Plasma Physics Laboratory) and PEGASUS Toroidal Experiment (University of Wisconsin-Madison) are focused on studying EBWs for heating and current drive. On NSTX, two remotely steered, quad-ridged antennas have been installed to measure 8-40 GHz (fundamental, second and third harmonics) thermal EBW emission (EBE) via the oblique B-X-O mode conversion process. This diagnostic has been successfully used to map the EBW mode conversion efficiency as a function of poloidal and toroidal angles on NSTX. Experimentally measured mode conversion efficiencies of 70±20% have been measured for 15.5 GHz (fundamental) emission in L-mode discharges, in agreement with a numerical EBE simulation. However, much lower mode conversion efficiencies of 25±10% have been measured for 25 GHz (second harmonic) emission in L-mode plasmas. Numerical modeling of EBW propagation and damping on the very-low aspect ratio PEGASUS Toroidal Experiment has been performed using the GENRAY ray-tracing code and CQL3D Fokker-Planck code in support of planned EBW heating and current drive (EBWCD) experiments. Calculations were performed for 2.45 GHz waves launched with a 10 cm poloidal extent for a variety of plasma equilibrium configurations. Poloidal launch scans show that driven current is maximum when the poloidal launch angle is between 10 and 25 degrees

  2. Electron Bernstein Wave Research on NSTX and PEGASUS

    International Nuclear Information System (INIS)

    Spherical tokamaks (STs) routinely operate in the overdense regime (ωpe>>ωce), prohibiting the use of standard ECCD and ECRH. However, the electrostatic electron Bernstein wave (EBW) can propagate in the overdense regime and is strongly absorbed and emitted at the electron cyclotron resonances. As such, EBWs offer the potential for local electron temperature measurements and local electron heating and current drive. A critical challenge for these applications is to establish efficient coupling between the EBWs and electromagnetic waves outside the cutoff layer. Two STs in the U.S., the National Spherical Tokamak Experiment (NSTX, at Princeton Plasma Physics Laboratory) and PEGASUS Toroidal Experiment (University of Wisconsin-Madison) are focused on studying EBWs for heating and current drive. On NSTX, two remotely steered, quad-ridged antennas have been installed to measure 8-40 GHz (fundamental, second and third harmonics) thermal EBW emission (EBE) via the oblique B-X-O mode conversion process. This diagnostic has been successfully used to map the EBW mode conversion efficiency as a function of poloidal and toroidal angles on NSTX. Experimentally measured mode conversion efficiencies of 70±20% have been measured for 15.5 GHz (fundamental) emission in L-mode discharges, in agreement with a numerical EBE simulation. However, much lower mode conversion efficiencies of 25±10% have been measured for 25 GHz (second harmonic) emission in L-mode plasmas. Numerical modeling of EBW propagation and damping on the very-low aspect ratio PEGASUS Toroidal Experiment has been performed using the GENRAY ray-tracing code and CQL3D Fokker-Planck code in support of planned EBW heating and current drive (EBWCD) experiments. Calculations were performed for 2.45 GHz waves launched with a 10 cm poloidal extent for a variety of plasma equilibrium configurations. Poloidal launch scans show that driven current is maximum when the poloidal launch angle is between 10 and 25 degrees

  3. Ion Bernstein wave experiments on the Alcator C tokamak

    International Nuclear Information System (INIS)

    Ion Bernstein wave experiments are carried out on the Alcator C tokamak to study wave excitation, propagation, absorption, and plasma heating due to wave power absorption. It is shown that ion Bernstein wave power is coupled into the plasma and follows the expected dispersion relation. The antenna loading is maximized when the hydrogen second harmonic layer is positioned just behind the antenna. Plasma heating results at three values of the toroidal magnetic field are presented. Central ion temperature increases of ΔT/sub i//Ti /approx lt/ 0.1 and density increases Δn/n 6s/sup /minus/1/ for plasmas within the density range 0.6 /times/ 1020m/sup /minus/3/ ≤ /bar n//sub e/ ≤ 4 /times/ 1020m/sup /minus/3/ and magnetic fields 2.4 ≥ ω/Ω/sub H/ ≥ 1.1. The density increases is usually accompanied by an improvement in the global particle confinement time relative to the Ohmic value. The ion heating rate is measured to be ΔT/sub i//P/sub rf/ ≅ 2-4.5 eV/kW at low densities. At higher densities /bar n//sub e/ ≤ 1.5 /times/ 1020m/sup /minus/3/ the ion heating rate dramatically decreases. It is shown that the decrease in the ion heating rate can be explained by the combined effects of wave scattering through the edge turbulence and the decreasing on energy confinement of these discharges with density. The effect of observed edge turbulence is shown to cause a broadening of the rf power deposition profile with increasing density. It is shown that the inferred value of the Ohmic ion thermal conduction, when compared to the Chang-Hinton neoclassical prediction, exhibits an increasing anomaly with increasing plasma density

  4. Fundamental Investigation of Electron Bernstein Wave Heating and Current Drive at the WEGA Stellarator

    Czech Academy of Sciences Publication Activity Database

    Laqua, H.P.; Andruczyk, D.; Marsen, S.; Otte, M.; Podoba, Y.; Preinhaelter, Josef; Urban, Jakub

    Geneva: IAEA, 2008, EXP6-18-EXP6-18. ISBN N. [IAEA Fusion Energy Conference/22nd./. Geneva (CH), 13.10.2008-18.10.2008] R&D Projects: GA ČR GA202/08/0419 Institutional research plan: CEZ:AV0Z20430508 Keywords : Conversion * Emission * Stellarators * Electron Bernstein waves * Simulation * WEGA Subject RIV: BL - Plasma and Gas Discharge Physics http://www-pub.iaea.org/MTCD/Meetings/FEC2008/ex_p6-18.pdf

  5. Characteristics of ion Bernstein wave heating in JIPPT-II-U tokamak

    International Nuclear Information System (INIS)

    Using a transport code combined with an ion Bernstein wave tokamak ray tracing code, a modelling code for the ion Bernstein wave heating has been developed. Using this code, the ion Bernstein wave heating experiment on the JIPPT-II-U tokamak has been analyzed. It is assumed that the resonance layer is formed by the third harmonic of deuterium-like ions, such as fully ionized carbon, and oxygen ions near the plasma center. For wave absorption mechanisms, electron Landau damping, ion cyclotron harmonic damping, and collisional damping are considered. The characteristics of the ion Bernstein wave heating experiment, such as the ion temperature increase, the strong dependence of the quality factor on the magnetic field strength, and the dependence of the ion temperature increment on the input power, are well reproduced

  6. Characteristics of ion Bernstein wave heating in JIPPT-II-U tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, M.; Ono, M.

    1985-11-01

    Using a transport code combined with an ion Bernstein wave tokamak ray tracing code, a modelling code for the ion Bernstein wave heating has been developed. Using this code, the ion Bernstein wave heating experiment on the JIPPT-II-U tokamak has been analyzed. It is assumed that the resonance layer is formed by the third harmonic of deuterium-like ions, such as fully ionized carbon, and oxygen ions near the plasma center. For wave absorption mechanisms, electron Landau damping, ion cyclotron harmonic damping, and collisional damping are considered. The characteristics of the ion Bernstein wave heating experiment, such as the ion temperature increase, the strong dependence of the quality factor on the magnetic field strength, and the dependence of the ion temperature increment on the input power, are well reproduced.

  7. Linear conversion of electromagnetic waves into electron Bernstein waves in an arbitrary inhomogeneous plasma slab

    International Nuclear Information System (INIS)

    A theory of coupling between electromagnetic and electron Bernstein waves in a plasma slab is presented. The theory uses an approach that associates the linear mode conversion with the singularity of the cold plasma wave equation at the upper hybrid resonance (UHR). The singularity results in linear interaction of cold plasma (electromagnetic) and hot plasma (Bernstein) modes. Applicability of the WKB theory to interacting modes is not required. In this method the full solution of the mode conversion problem including calculation of the excited Bernstein wave complex amplitude is reduced to finding a solution to the cold plasma wave equation, which describes dissipative wave power absorption at the UHR. This method is applicable to a variety of plasma configurations practically without limitations on the inhomogeneity scale-length. It permits one to consider in the framework of a single procedure particular cases like direct tunnelling of the incident wave, O-X-B conversion and transformation of the X-mode launched from the high-field side of a tokamak and having free access to the UHR

  8. Experimental and Theoretical Investigation of Synergy between Ion Bernstein and Lower Hybrid Waves in PBX-M

    Energy Technology Data Exchange (ETDEWEB)

    A. Cardinali; A. Post-Zwicker; F. Paoletti; S. Bernabei; S. Von Goeler; W. Tighe

    1998-02-01

    The synergistic behavior of lower hybrid and ion Bernstein waves on the Princeton Beta Experiment-Modified tokamak [Phys. Fluids B 2, 1271 (1990)] is experimentally studied using a 2-D hard X-ray camera. The hard X-ray bremsstrahlung emission from suprathermal electrons, generated with lower hybrid current drive, is enhanced during ion Bernstein wave power injection. This enhancement is observed in limited regions of space suggesting the formation of localized current channels. The effects on plasma electrons during combined application of these two types of waves are theoretically investigated using a quasilinear model. The numerical code simultaneously solves the 3-D (R, Z, {Phi}) toroidal wave equation for the electric field (in the WKBJ approximation) and the Fokker-Planck equation for the distribution function in two dimensions (v{sub parallel}, v{sub perpendicular}) with an added quasilinear diffusion coefficient. The radial profile of the non-inductively generated current density, the transmitted power traces and the total power damping curve are calculated. The beneficial effects of a combined utilization of ion Bernstein and lower hybrid waves on the current drive are emphasized. The numerical results are compared with the experimental observations.

  9. Lower hybrid and Electron Bernstein Wave current drive experiments in MST

    International Nuclear Information System (INIS)

    Inductive current profile modification in MST has been successful in reducing fluctuations and transport but is transient and radially non-localized. Current profile control with rf waves offers steady and more precise control. Studies of lower hybrid (LH) wave and electron Bernstein wave (EBW) injection are underway. This first application of LH waves to the high dielectric RFP presents challenges in rf physics, e.g., limited wave accessibility. The novel interdigital line antenna, chosen because of stringent vacuum vessel constraints, operates at 800 MHz and nparallel ∼ 7.5 parameters chosen to drive current in the edge (r/a ∼ 0.8) with strong single-pass absorption. Extensive antenna loading studies have been performed to validate the design up to the present source power limit of 225 kW with up to 125 kW being coupled to the plasma. Hard-x-ray emission with energies as high as 50 keV has been observed. The emission is spatially localized to the antenna location with a toroidal spread of about 60 degrees. This interesting toroidal localization of the emission that occurs in the dominantly poloidal magnetic field of the RFP could result from the formation of a localized current structure. Presently, a 250 kW system designed to heat electrons and drive current via the electron Bernstein wave is in operation on the MST reversed field pinch. The antenna is a grill of four half-height S-band waveguides with each arm powered by a separate, phase controlled traveling wave tube amplifier at 3.6 GHz. The X-mode polarization is being used to launch electromagnetic waves that mode convert to EBWs in the edge plasma. Coupling to the plasma (as measured by the reflected power ratio) is dependent on the relative phasing between adjacent waveguides. The total reflected power can be maintained near the 10% level. The antenna face is outfitted with a pair of triple Langmuir probes to measure local electron density; the density gradient at the upper hybrid resonance

  10. Localized electron heating experiments by ion Bernstein wave in the TNT-A tokamak

    International Nuclear Information System (INIS)

    Plasma heating by ion Bernstein wave in the range of 2 ωD D is investigated in deuterium dominant plasma of the TNT-A tokamak. The localized electron heating is observed at the harmonic (3 ωD) and subharmonic (2.5 ωD) resonance layers, while the electron heating on the whole plasma region is observed at ω = 2 ωD. It is also shown that the heating is efficient and heating layer is localized by ion Bernstein wave in comparison with fast magnetosonic wave. (author)

  11. Electron-Bernstein-wave current drive in an overdense plasma at the Wendelstein 7-AS stellarator

    International Nuclear Information System (INIS)

    Electron-Bernstein-wave (EBW) current drive in an overdense plasma was demonstrated at the Wendelstein 7-AS stellarator for the first time. The EBWs were generated by O-X-B mode conversion. The relatively high current drive efficiency was consistent with theoretical predictions. The experiments provided first investigations of EBW phase space interaction for wave refractive indices much larger than unity

  12. Ion Bernstein-wave excitation via finite-Larmor-radius mode-transformation process

    International Nuclear Information System (INIS)

    It is shown that in the ion cyclotron range of frequency ω less than or equal to 2 Ω/sub i/, the finite-Larmor-radius effect removes the wave singularity at the lower-hybrid resonance layer, enabling an externally initiated electron plasma wave to propagate freely through the resonance layer, transforming continuously into an ion Bernstein wave. In an ACT-1 hydrogen plasma (T/sub e/ approx. = 2.5 eV, T/sub i/ approx. = 1.5 eV), linear excitation of ion Bernstein waves has been investigated experimentally for ω approx. = 2Ω/sub i/. The mode-transformation process resulting in a strong ω approx. = 2 Ω/sub i/ ion Berstein wave excitation without observable reflections has been experimentally verified. Detailed measurements of wave dispersion relation and of the wave-packet trajectory show excellent agreement with theory

  13. Preliminary Observation on Coordination of Pellet Injection and Ion Bernstein Wave on a HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    杨愚; 赵燕平; 李建刚; 万宝年; 罗家融; 辜学茂

    2002-01-01

    A pellet injection (PI) experiment was performed during the application of the ion Bernstein wave on a HT-7tokamak. A preliminary coordination effect was observed. With a lower wave power, shortly after PI, the couplingof the wave was enhanced, and the particle confinement was improved. With higher power, off-axis heating for 15% at about a/3 in the low field side was observed.

  14. Measurements of Intrinsic Ion Bernstein Waves in a Tokamak by Collective Thomson Scattering

    DEFF Research Database (Denmark)

    Korsholm, Søren Bang; Stejner Pedersen, Morten; Bindslev, Henrik; Furtula, Vedran; Leipold, Frank; Meo, Fernando; Michelsen, Poul; Moseev, Dmitry; Nielsen, Stefan Kragh; Salewski, Mirko; de Baar, M.; Delabie, E.; Kantor, M.; Bürger, A.

    2011-01-01

    In this Letter we report measurements of collective Thomson scattering (CTS) spectra with clear signatures of ion Bernstein waves and ion cyclotron motion in tokamak plasmas. The measured spectra are in accordance with theoretical predictions and show clear sensitivity to variation in the density...

  15. Mode-converted electron Bernstein waves for heating and current drive in NSTX

    International Nuclear Information System (INIS)

    The power coupled to electron Bernstein waves in a triplet mode conversion resonator from a fast X-mode at the plasma edge in NSTX is shown to be > 80% for fce ce. The EBW damping in the plasma is strong and localized and, thus, should be useful for heating, current drive, or profile control. (author)

  16. Plasma heating via electron Bernstein wave heating using ordinary and extraodinary mode

    Directory of Open Access Journals (Sweden)

    A. Parvazian

    2008-03-01

    Full Text Available Magnetically confined plasma can be heated with high power microwave sources. In spherical torus the electron plasma frequency exeeds the electron cyclotron frequency (EC and, as a consequence, electromagnetic waves at fundamental and low harmonic EC cannot propagate within the plasma. In contrast, electron Bernstein waves (EBWs readily propagate in spherical torus plasma and are absorbed strongly at the electron cyclotron resonances. In order to proagate EBWs beyond the upper hybrid resonance (UHR, that surrounds the plasma, the EBWs must convert via one of two processes to either ordinary (O-mode or extraordinary (X-mode electromagnetic waves. O-mode and X-mode electromagnetic waves lunched at the plasma edge can convert to the electron Bernstein waves (EBWs which can propagate without and cut-off into the core of the plasma and damp on electrons. Since the electron Bernstein wave (EBW has no cut-off limits, it is well suited to heat an over-dense plasma by resonant absorption. An important problem is to calculate mode conversion coefficient that is very sensitive to density. Mode conversion coefficient depends on Budden parameter ( ñ and density scale length (Ln in upper hybrid resonance (UHR. In Mega Ampere Spherical Tokamak (MAST, the optimized conversion efficiency approached 72.5% when Ln was 4.94 cm and the magnetic field was 0.475 Tesla in the core of the plasma.

  17. Flow shear suppression of turbulence using externally driven ion Bernstein and Alfven waves

    International Nuclear Information System (INIS)

    The utilization of externally-launched radio-frequency waves as a means of active confinement control through the generation of sheared poloidal flows is explored. For low-frequency waves, kinetic Alfven waves are proposed, and are shown to drive sheared E x B flows as a result of the radial variation in the electromagnetic Reynolds stress. In the high frequency regime, ion Bernstein waves are considered, and shown to generate sheared poloidal rotation through the ponderomotive force. In either case, it is shown that modest amounts of absorbed power (∼ few 100 kW) are required to suppress turbulence in a region of several cm radial width. 9 refs

  18. Propagation and absorption of Ion Bernstein waves in U-2M torsatron by ray tracing technique

    International Nuclear Information System (INIS)

    Ion Bernstein modes with frequencies higher than the ion cyclotron frequency are planned to be applied to produce and heat the Uragan-2M plasma. This brief report gives the propagation and absorption ray-tracing studies of these waves in the Uragan-2M device, taking into account the three-dimensional non-uniformities of the plasma parameters and the magnetic field. 4 refs, 5 figs

  19. Bernstein-Greene-Kruskal waves in relativistic cold plasma

    Science.gov (United States)

    Singh Verma, Prabal; Sengupta, Sudip; Kaw, Predhiman

    2012-03-01

    We construct the longitudinal traveling wave solution [Akhiezer and Polovin, Sov. Phys. JETP 3, 696 (1956)] from the exact space and time dependent solution of relativistic cold electron fluid equations [Infeld and Rowlands, Phys. Rev. Lett. 62, 1122 (1989)]. Ions are assumed to be static. We also suggest an alternative derivation of the Akhiezer Polovin solution after making the standard traveling wave Ansatz.

  20. A survey of electron Bernstein wave heating and current drive potential for spherical tokamaks

    Czech Academy of Sciences Publication Activity Database

    Urban, Jakub; Decker, J.; Peysson, Y.; Preinhaelter, Josef; Shevchenko, V.; Taylor, G.; Vahala, L.; Vahala, G.

    2011-01-01

    Roč. 51, č. 8 (2011), 083050-083050. ISSN 0029-5515 R&D Projects: GA ČR GA202/08/0419; GA MŠk 7G10072 Institutional research plan: CEZ:AV0Z20430508 Keywords : spherical tokamak * electron Bernstein wave (EBW) * heating * current drive * electron cyclotron wave Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 4.090, year: 2011 http://iopscience.iop.org/0029-5515/51/8/083050/pdf/0029-5515_51_8_083050.pdf

  1. Tokamak ion temperature determination via CW far-infrared laser scattering from externally excited ion Bernstein waves

    International Nuclear Information System (INIS)

    The paper describes a successful proof-of-principle experimental determination of tokamak ion temperature using cw far-infrared (FIR) collective laser scattering from externally excited ion Bernstein waves. It is shown that a viable wave excitation technique for tokamak plasmas is mode conversion of an externally launched fast Alfven wave. A fit of the experimentally determined ion Bernstein wave dispersion to the temperature-dependent theoretical dispersion yields the local ion temperature. Partial ion temperature profiles (chord-averaged) have been obtained with temperature values consistent with charge-exchange measurements. (author)

  2. Ion Bernstein waves in a plasma with a kappa velocity distribution

    International Nuclear Information System (INIS)

    Using a Vlasov-Poisson model, a numerical investigation of the dispersion relation for ion Bernstein waves in a kappa-distributed plasma has been carried out. The dispersion relation is found to depend significantly on the spectral index of the ions, κi, the parameter whose smallness is a measure of the departure from thermal equilibrium of the distribution function. Over all cyclotron harmonics, the typical Bernstein wave curves are shifted to higher wavenumbers (k) if κi is reduced. For waves whose frequency lies above the lower hybrid frequency, ωLH, an increasing excess of superthermal particles (decreasing κi) reduces the frequency, ωpeak, of the characteristic peak at which the group velocity vanishes, while the associated kpeak is increased. As the ratio of ion plasma to cyclotron frequency (ωpi/ωci) is increased, the fall-off of ω at large k is smaller for lower κi and curves are shifted towards larger wavenumbers. In the lower hybrid frequency band and harmonic bands above it, the frequency in a low-κi plasma spans only a part of the intraharmonic space, unlike the Maxwellian case, thus exhibiting considerably less coupling between adjacent bands for low κi. It is suggested that the presence of the ensuing stopbands may be a useful diagnostic for the velocity distribution characteristics. The model is applied to the Earth's plasma sheet boundary layer in which waves propagating perpendicularly to the ambient magnetic field at frequencies between harmonics of the ion cyclotron frequency are frequently observed

  3. Ion Bernstein wave heating experiments on PBX-M

    International Nuclear Information System (INIS)

    A multi-megawatt level IBWH experiment on PBX-M1 is in preparation. The goal of the expriment is to contribute to the attainment of the high beta, second regime of stability. The high power IBWH will be used as an additional heating power source to supplement the existing 6 MW of NBI power to achieve higher β values in PBX-M. Bulk ion heating via IBW excitation with localized, off-axis deposition can be used to modify the pressure profile for improved plasma stability at high β. The high power off-axis heating in principle can generate a significant boostrap current 2(∼30%) in the outer region of the PBX-M plasma complementing LHCD for broadening the current profiles. It is also interesting to note that the available rf power (∼4 MW) is comparable to the predicted power levels required for the rf ponderomotive stabilization of pressure driven modes (such as the high-n ballooning3 and external kink modes4) for the closely fitted stabilizing shell configuration of PBX-M. There are, however, several experimental factors that require careful consideration in planning a high power experiment. Four important factors are discussed here in some detail: 1. Antenna location. 2. Effects of parallel electric fields. 3. Modification of launched wave spectrum due to antenna misalignement 4. Possible interference of wave launching by protective limiters

  4. Variational symplectic particle-in-cell simulation of nonlinear mode conversion from extraordinary waves to Bernstein waves

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Jianyuan; Liu, Jian, E-mail: jliuphy@ustc.edu.cn [Department of Modern Physics and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China); Key Laboratory of Geospace Environment, CAS, Hefei, Anhui 230026 (China); Qin, Hong [Department of Modern Physics and School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China); Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Yu, Zhi; Xiang, Nong [Theory and Simulation Division, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2015-09-15

    In this paper, the nonlinear mode conversion of extraordinary waves in nonuniform magnetized plasmas is studied using the variational symplectic particle-in-cell simulation. The accuracy of the nonlinear simulation is guaranteed by the long-term accuracy and conservativeness of the symplectic algorithm. The spectra of the electromagnetic wave, the evolution of the wave reflectivity, the energy deposition profile, and the parameter-dependent properties of radio-frequency waves during the nonlinear mode conversion are investigated. It is illustrated that nonlinear effects significantly modify the physics of the radio-frequency injection in magnetized plasmas. The evolutions of the radio-frequency wave reflectivity and the energy deposition are observed, as well as the self-interaction of the Bernstein waves and mode excitations. Even for waves with small magnitude, nonlinear effects can also become important after continuous wave injections, which are common in the realistic radio-frequency wave heating and current drive experiments.

  5. Variational symplectic particle-in-cell simulation of nonlinear mode conversion from extraordinary waves to Bernstein waves

    International Nuclear Information System (INIS)

    In this paper, the nonlinear mode conversion of extraordinary waves in nonuniform magnetized plasmas is studied using the variational symplectic particle-in-cell simulation. The accuracy of the nonlinear simulation is guaranteed by the long-term accuracy and conservativeness of the symplectic algorithm. The spectra of the electromagnetic wave, the evolution of the wave reflectivity, the energy deposition profile, and the parameter-dependent properties of radio-frequency waves during the nonlinear mode conversion are investigated. It is illustrated that nonlinear effects significantly modify the physics of the radio-frequency injection in magnetized plasmas. The evolutions of the radio-frequency wave reflectivity and the energy deposition are observed, as well as the self-interaction of the Bernstein waves and mode excitations. Even for waves with small magnitude, nonlinear effects can also become important after continuous wave injections, which are common in the realistic radio-frequency wave heating and current drive experiments

  6. The new features of ion Bernstein Wave Heating in JIPP T-IIU tokamak

    International Nuclear Information System (INIS)

    Ion Bernstein Wave Heating experiment was conducted in JIPP T-IIU tokamak. A relatively high frequency, 130 MHz, was used to reduce impurity influx and IBW power up to 400kW was injected without plasma disruption. It was found that the radial profiles of electron density, electron temperature, and ion temperature are all peaked during the IBWH. It was also found that ion distribution function does not have high energy tail above certain critical energy. These are favorable and useful features in optimizing fusion reactivity in reactor applications. (author)

  7. Power Deposition of Ion Bernstein Wave Heating on the HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    BAO Yi; LI Jian-Gang; ZHAO Yan-Ping; CUI Ning-Zhuo

    2001-01-01

    Effcient direct heating of electrons by ion Bernstein waves has been obtained on the HT-7 tokamak. Off-axis heating, which is considered to be the result of electron Landau damping, was observed and studied by means of soft x-ray imaging. The measured power deposition was found to be independent of magnetic field through scanning the toroidal field from 1.5 to 1.7 T, in contrast to the ion heating results. It is suggested that the electron Landau damping is dominant in this heating regime.

  8. Alfven Eigenmode And Ion Bernstein Wave Studies For Controlling Fusion Alpha Particles

    CERN Document Server

    Franklin, F R

    1999-01-01

    In magnetic confinement fusion reactor plasmas, the charged fusion products (such as alpha particles in deuterium-tritium plasmas) will be the dominant power source, and by controlling these charged fusion products using wave-particle interactions the reactor performance could be optimized. This thesis studies two candidate waves: Mode- Converted Ion Bernstein Waves (MCIBWs) and Alfvé n Eigenmodes (AEs). Rates of MCIBW-driven losses of alpha-like fast deuterons, previously observed in the Tokamak Fusion Test Reactor (TFTR), are reproduced by a new model so that the wave-particle diffusion coefficient can be deduced. The MCIBW power in TFTR is found to be ∼ 1/3 that needed for collisionless alpha particle control...

  9. Residual Bernstein-Greene-Kruskal-like waves after one-dimensional electron wave breaking in a cold plasma

    Science.gov (United States)

    Verma, Prabal Singh; Sengupta, Sudip; Kaw, Predhiman

    2012-07-01

    A one-dimensional particle in cell simulation of large amplitude plasma oscillations is carried out to explore the physics beyond wave breaking in a cold homogeneous unmagnetized plasma. It is shown that after wave breaking, all energy of the plasma oscillation does not end up as random kinetic energy of particles, but some fraction, which is decided by Coffey's wave breaking limit in warm plasma, always remains with two oppositely propagating coherent Bernstein-Greene-Kruskal like modes with supporting trapped particle distributions. The randomized energy distribution of untrapped particles is found to be characteristically non-Maxwellian with a preponderance of energetic particles.

  10. Formation of core transport barrier and CH-Mode by ion Bernstein wave heating in PBX-M

    International Nuclear Information System (INIS)

    Observation of core transport barrier formation (for particles, ion and electron energies, and toroidal momentum) by ion Bernstein wave heating (IBWH) in PBX-M plasma is reported. The formation of a transport barrier leads to a strong peaking and significant increase of the core pressure (70%) and toroidal momentum (20%), and has been termed the core-high confinement mode (CH-Mode). This formation of a transport barrier is consistent, in terms of the expected barrier location as well as the required threshold power, with a theoretical model based on the poloidal sheared flow generation by the ion Bernstein wave power. The use of ion Bernstein wave (IBW) induced sheared flow as a tool to control plasma pressure and bootstrap current profiles shows a favorable scaling for the use in future reactor grade tokamak plasmas

  11. Parameter dependence of ray trajectory and damping for the ion Bernstein wave in the TNT-A tokamak

    International Nuclear Information System (INIS)

    The dependence of ray trajectories and damping on various plasma parameters was studied using three-dimensional ray tracing for an ion Bernstein wave in the TNT-A tokamak. The condition for wave power absorption dominated by electron Landau damping was also estimated. (author)

  12. Improved plasma confinement by Ion Bernstein Waves (IBWs) interacting with ions in JET (Joint European Torus)

    International Nuclear Information System (INIS)

    A new coupling scheme of ion Bernstein waves (IBW) to plasma ions, by mode conversion of fast waves, has been tested in D-3He plasma of the JET tokamak. Injecting 4.8 MW ion cyclotron radio frequency power, 1.8 MW IBW power absorption on deuterons occurs at the fundamental cyclotron resonant layer, which is located in the high field side near the plasma edge (R = 2.1 m). Plasma sheared flows, ponderomotively induced by IBW, are observed near the edge, producing an ExB shearing rate of 5 MHz, higher than the threshold expected for turbulence suppression. Transport analysis shows a 70% reduction of the thermal diffusivity of both electrons and ions in the edge plasma region where the sheared flows are observed. (author)

  13. Parametric excitation of electron Bernstein waves by radio waves in the ionosphere and its possible consequence for airglow

    International Nuclear Information System (INIS)

    A high power radio wave, launched into the polar ionosphere at angle θ with the earth's magnetic field from a ground-based transmitter in the vicinity of twice the electron cyclotron frequency (2.75 MHz), is reported to create an airglow at an effective radiated power (ERP) = 10 MW. We interpret this result as a consequence of parametric decay of the radio wave into an electron Bernstein wave (EBW) and an ion acoustic wave (IAW). The oscillatory velocity of electrons due to the pump couples with the density perturbation due to the IAW to produce a current, driving the Bernstein mode. The latter, in connection with the pump, exerts a ponderomotive force on electrons, driving the IAW. The growth rate of the parametric instability is maximum for θ = 0. At the same time, for any given value of θ, the growth rate increases with b(=k12vth2/2ωc2) and attains a maximum around b ∼ 2, then falls gradually. The EBW produces energetic electrons via cyclotron damping. These electrons collide with the neutral atoms of the plasma to excite them to higher energy states. As the excited atoms return to lower energy states, they radiate in the visible

  14. Interpreting ~1 Hz magnetic compressional waves in Mercury's inner magnetosphere in terms of propagating ion-Bernstein waves

    Science.gov (United States)

    Boardsen, S. A.; Kim, E.-H.; Raines, J. M.; Slavin, J. A.; Gershman, D. J.; Anderson, B. J.; Korth, H.; Sundberg, T.; Schriver, D.; Travnicek, P.

    2015-06-01

    We show that ~1 Hz magnetic compressional waves observed in Mercury's inner magnetosphere could be interpreted as ion-Bernstein waves in a moderate proton beta ~0.1 plasma. An observation of a proton distribution with a large planetary loss cone is presented, and we show that this type of distribution is highly unstable to the generation of ion-Bernstein waves with low magnetic compression. Ray tracing shows that as these waves propagate back and forth about the magnetic equator; they cycle between a state of low and high magnetic compression. The group velocity decreases during the high-compression state leading to a pileup of compressional wave energy, which could explain the observed dominance of the highly compressional waves. This bimodal nature is due to the complexity of the index of refraction surface in a warm plasma whose upper branch has high growth rate with low compression, and its lower branch has low growth/damping rate with strong compression. Two different cycles are found: one where the compression maximum occurs at the magnetic equator and one where the compression maximum straddles the magnetic equator. The later cycle could explain observations where the maximum in compression straddles the equator. Ray tracing shows that this mode is confined within ±12° magnetic latitude which can account for the bulk of the observations. We show that the Doppler shift can account for the difference between the observed and model wave frequency, if the wave vector direction is in opposition to the plasma flow direction. We note that the Wentzel-Kramers-Brillouin approximation breaks down during the pileup of compressional energy and that a study involving full wave solutions is required.

  15. Ion Bernstein wave heating experiment on JIPPT-II-U device

    International Nuclear Information System (INIS)

    Ion Bernstein wave heating is investigated in the JIPPT-II-U tokamak plasma, n-bar sub(o) asymptoticaly equals 1.5 x 1013 cm-3, Tsub(eo) asymptoticaly equals 700 eV, and Tsub(io) = 300 eV for Psub(rf) 1-- 100 kW. In a two-ion-species helium-hydrogen plasma, the third harmonics of helium minority cyclotron resonance (deuterium-like) is heated. The background hydrogen ion temperature monitored by charge-exchange shows a significant rise, ΔTsub(i) 1-- 600 eV, when the helium harmonic resonance layer is placed near the center of the plasma. Typical observed hydrogen ion heating quality factor, ΔTsub(i)/Psub(rf)/n-barsub(o), is 1-- 10 eV/kW/1013cm-3. The dependence of ion heating efficiency on rf power, magnetic field and ion concentration is presented. (author)

  16. Alfven Eigenmode And Ion Bernstein Wave Studies For Controlling Fusion Alpha Particles

    CERN Document Server

    Heeter, R F

    1999-01-01

    In magnetic confinement fusion reactor plasmas, the charged fusion products (such as alpha particles in deuterium-tritium plasmas) will be the dominant power source, and by controlling these charged fusion products using wave-particle interactions the reactor performance could be optimized. This thesis studies two candidate waves: Mode-Converted Ion Bernstein Waves (MCIBWs) and Alfvén Eigenmodes (AEs). Rates of MCIBW-driven losses of alpha-like fast deuterons, previously observed in the Tokamak Fusion Test Reactor (TFTR), are reproduced by a new model so that the wave-particle diffusion coefficient can be deduced. The MCIBW power in TFTR is found to be ∼ 1/3 that needed for collisionless alpha particle control. A reasonable reactor power scaling is derived. To study AEs, existing magnetic fluctuation probes at the Joint European Torus (JET) have been absolutely calibrated from 30–500 kHz for the first time, allowing fluctuation measurements with &vbm0;dBpol&vbm0;/B0&am...

  17. A survey of electron Bernstein wave heating and current drive potential for spherical tokamaks

    CERN Document Server

    Urban, Jakub; Peysson, Yves; Preinhaelter, Josef; Shevchenko, Vladimir; Taylor, Gary; Vahala, Linda; Vahala, George

    2011-01-01

    The electron Bernstein wave (EBW) is typically the only wave in the electron cyclotron (EC) range that can be applied in spherical tokamaks for heating and current drive (H&CD). Spherical tokamaks (STs), which feature relatively high neutron flux and good economy, operate generally in high-beta regimes, in which the usual EC O- and X- modes are cut-off. In this case, EBWs seem to be the only option that can provide features similar to the EC waves---controllable localized H&CD that can be utilized for core plasma heating as well as for accurate plasma stabilization. The EBW is a quasi-electrostatic wave that can be excited by mode conversion from a suitably launched O- or X-mode; its propagation further inside the plasma is strongly influenced by the plasma parameters. These rather awkward properties make its application somewhat more difficult. In this paper we perform an extensive numerical study of EBW H&CD performance in four typical ST plasmas (NSTX L- and H-mode, MAST Upgrade, NHTX). Coupled...

  18. Electron heating by mode-converted ion-Bernstein waves in ICRF heating of tokamak plasmas

    International Nuclear Information System (INIS)

    In a tokamak plasma, ion-Bernstein waves (IBW) can be excited by mode-conversion of the externally launched fast wave for ICRF heating. This conversion process is known to be efficient for low k/sub parallel/'s which carry substantial power from a single loop antenna. A detailed numerical analysis of the propagation of the IBW shows that the initial small k/sub parallel/ are significantly enhanced along the rays due to toroidal effects. The upshift can occur for short radial distances of propagation and is large enough so that the IBW can Landau damp onto the electrons. This could help explain the observed strong electron heating by ICRF waves in tokamak plasmas. The numerical ray trajectory analysis is done in toroidal geometry for a hot Maxwellian plasma with gradients in temperature, density, toroidal and poloidal magnetic fields included in a WKB sense. A simple analytical model is derived which explains the upshift in k/sub parallel/ and gives results very close to the numerically obtained values. Approximate analytical conditions for appreciable electron Landau damping of the IBW are also given

  19. Ion Bernstein wave antenna loading measurements on the DIII-D tokamak

    Science.gov (United States)

    Mayberry, M. J.; Pinsker, R. I.; Petty, C. C.; Porkolab, M.; Chiu, S. C.; Cary, W. P.; Prater, R.

    1993-04-01

    Antenna loading measurements carried out during high power ion Bernstein wave (IBW) heating experiments on the DIII-D tokamak indicate that efficient, direct coupling to the IBW at ω lesssim 2ωci as predicted by linear coupling theory did not occur. Whereas strong peaking in the loading resistance near cyclotron harmonics is predicted for high edge densities (ω front of the antenna, thus allowing coupling to the cold plasma lower hybrid wave (LHW). A linear LHW coupling code including the modified density profile due to the ponderomotive force reproduces the measured dependence of antenna loading on toroidal magnetic field, edge density, antenna frequency and antenna phasing. Further evidence for the ponderomotive force is obtained from reactive loading measurements which indicate that the plasma is pushed away from the antenna as the radiofrequency power level is increased. The results indicate that the lack of central ion heating observed during DIII-D IBW experiments may be due to a lack of efficient mode transformation from the coupled LHW to a centrally propagating IBW, possibly as a result of nonlinear mechanism(s)

  20. Modification of boundary plasma behavior by Ion Bernstein Wave heating on the HT-7 tokamak

    International Nuclear Information System (INIS)

    The boundary plasma behavior during Ion Bernstein Wave heating was investigated using Langmuir probe arrays on the HT-7 tokamak. A distinct weak turbulence regime was reproducibly observed in the 30 MHz IBW heated plasmas with RF power larger than 120 kW, which resulted in a particle confinement improvement of a factor of 2. The strong suppression and decorrelation effect of fluctuations resulted in the turbulent particle flux dropping by more than an order of magnitude in the plasma boundary region. An additional inward radial electric field and associated poloidal ExB flows were produced, which could account for the additional poloidal velocity in the electron diamagnetic direction at some radial locations of the boundary plasma. The electrostatic fluctuations were nearly completely decorrelated in the high frequency region and only low frequency fluctuations remained. The poloidal correlation was considerably reduced in the high poloidal wave number region and only the fluctuations with long poloidal wavelength remained. Three-wave nonlinear phase coupling between the whole frequency domain and the very low frequency region increased significantly in both the plasma edge and the SOL. Quite low frequency fluctuations (about 5 kHz) were generated, which dominated the boundary turbulence during IBW heating. Detailed analyses suggested that, when an IBW with a frequency of 30 MHz was launched into a plasma with the toroidal magnetic field between 1.75 T and 2.0 T, the ion cyclotron resonant layer of 5/2.D was located in the plasma edge region. The poloidal ExB sheared flows generated by IBW near this layer due to a ponderomotive interaction were found to be the mechanism underlying these phenomena. (author)

  1. On the multistream approach of relativistic Weibel instability. II. Bernstein-Greene-Kruskal-type waves in magnetic trapping

    Science.gov (United States)

    Ghizzo, A.

    2013-08-01

    The stationary state with magnetically trapped particles is investigated at the saturation of the relativistic Weibel instability, within the "multiring" model in a Hamiltonian framework. The multistream model and its multiring extension have been developed in Paper I, under the assumption that the generalized canonical momentum is conserved in the perpendicular direction. One dimensional relativistic Bernstein-Greene-Kruskal waves with deeply trapped particles are addressed using similar mathematical formalism developed by Lontano et al. [Phys. Plasmas 9, 2562 (2002); Phys. Plasmas 10, 639 (2003)] using several streams and in the presence of both electrostatic and magnetic trapping mechanisms.

  2. Non inductive formation of an extremely overdense spherical Tokamak by electron Bernstein wave heating and current drive on LATE

    Directory of Open Access Journals (Sweden)

    Uchida Masaki

    2015-01-01

    Full Text Available An extremely overdense special Tokamak plasma has been non-inductively formed and maintained by electron Bernstein (EB wave heating and current drive in the Low Aspect ratio Torus Experiment (LATE device. The plasma current reaches 12 kA and the line-averaged electron density exceeds 7 times the plasma cut off density by injecting a 2.45 GHz microwave power of 60 kW. Such a highly overdense plasma is obtained when the upper hybrid resonance layer lies to the higher field side of the 2nd harmonic ECR layer, which may realize a good coupling to EB waves at their first propagation band. The effect of the injection polarization on the mode conversion rate to EB waves at the extremely overdense regime has been investigated and an improvement in the plasma current is observed.

  3. Collaboration on Modeling of Ion Bernstein Wave Antenna Array and Coupling to Plasma on Tokamak Fusion Text Reactor. Final report

    International Nuclear Information System (INIS)

    This proposal was peer reviewed and funded as a Collaboration on ''Low Phase Speed Radio Frequency Current Drive Experiments at the Tokamak Fusion Test Reactor''. The original plans we had were to carry out the collaboration proposal by including a post doctoral scientist stationed at PPPL. In response to a 60+% funding cut, all expenses were radically pruned. The post doctoral position was eliminated, and the Principal Investigator (T. Intrator) carried out the brunt of the collaboration. Visits to TFTR enabled T. Intrator to set up access to the TFTR computing network, database, and get familiar with the new antennas that were being installed in TFTR during an up to air. One unfortunate result of the budget squeeze that TFTR felt for its last year of operation was that the experiments that we specifically got funded to perform were not granted run time on TFTR., On the other hand we carried out some modeling of the electric field structure around the four strap direct launch Ion Bernstein Wave (IBW) antenna that was operated on TFTR. This turned out to be a useful exercise and shed some light on the operational characteristics of the IBW antenna and its coupling to the plasma. Because of this turn of events, the project was renamed ''Modeling of Ion Bernstein Wave Antenna Array and Coupling to Plasma on Tokamak Fusion Test Reactor''

  4. Fokker-Planck/Ray Tracing for Electron Bernstein and Fast Wave Modeling in Support of NSTX

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, R. W. [CompX, Del Mar, CA (United States)

    2009-11-12

    This DOE grant supported fusion energy research, a potential long-term solution to the world's energy needs. Magnetic fusion, exemplified by confinement of very hot ionized gases, i.e., plasmas, in donut-shaped tokamak vessels is a leading approach for this energy source. Thus far, a mixture of hydrogen isotopes has produced 10's of megawatts of fusion power for seconds in a tokamak reactor at Princeton Plasma Physics Laboratory in New Jersey. The research grant under consideration, ER54684, uses computer models to aid in understanding and projecting efficacy of heating and current drive sources in the National Spherical Torus Experiment, a tokamak variant, at PPPL. The NSTX experiment explores the physics of very tight aspect ratio, almost spherical tokamaks, aiming at producing steady-state fusion plasmas. The current drive is an integral part of the steady-state concept, maintaining the magnetic geometry in the steady-state tokamak. CompX further developed and applied models for radiofrequency (rf) heating and current drive for applications to NSTX. These models build on a 30 year development of rf ray tracing (the all-frequencies GENRAY code) and higher dimensional Fokker-Planck rf-collisional modeling (the 3D collisional-quasilinear CQL3D code) at CompX. Two mainline current-drive rf modes are proposed for injection into NSTX: (1) electron Bernstein wave (EBW), and (2) high harmonic fast wave (HHFW) modes. Both these current drive systems provide a means for the rf to access the especially high density plasma--termed high beta plasma--compared to the strength of the required magnetic fields. The CompX studies entailed detailed modeling of the EBW to calculate the efficiency of the current drive system, and to determine its range of flexibility for driving current at spatial locations in the plasma cross-section. The ray tracing showed penetration into NSTX bulk plasma, relatively efficient current drive, but a limited ability to produce current over

  5. Radio-frequency electromagnetic field measurements for direct detection of electron Bernstein waves in a torus plasma.

    Science.gov (United States)

    Yatsuka, Eiichi; Kinjo, Kiyotake; Morikawa, Junji; Ogawa, Yuichi

    2009-02-01

    To identify the mode-converted electron Bernstein wave (EBW) in a torus plasma directly, we have developed an interferometry system, in which a diagnostic microwave injected outside of the plasma column was directly detected with the probing antenna inserted into the plasma. In this work, plasma production and heating are achieved with 2.45 GHz, 2.5 kW electron cyclotron heating (ECH), whereas diagnostics are carried out with a lower power (10 W) separate frequency (1-2.1 GHz) microwave. Three components, i.e., two electromagnetic (toroidal and poloidal directions) and an electrostatic (if refractive index is sufficiently higher than unity, it corresponds to radial component), of ECRF electric field are simultaneously measured with three probing antennas, which are inserted into plasma. Selectivities of each component signal were checked experimentally. Excitation antennas have quite high selectivity of direction of linear polarization. As probing antennas for detecting electromagnetic components, we employed a monopole antenna with a length of 35 mm, and the separation of the poloidal (O-wave) and toroidal (X-wave) components of ECRF electric field could be available with this antenna. To detect EBW, which is an electrostatic wave, a small tip (1 mm) antenna was used. As the preliminary results, we detected signals that have three characteristics of EBW, i.e., short wavelength, backward propagation, and electrostatic. PMID:19256646

  6. Radio-frequency electromagnetic field measurements for direct detection of electron Bernstein waves in a torus plasma

    International Nuclear Information System (INIS)

    To identify the mode-converted electron Bernstein wave (EBW) in a torus plasma directly, we have developed an interferometry system, in which a diagnostic microwave injected outside of the plasma column was directly detected with the probing antenna inserted into the plasma. In this work, plasma production and heating are achieved with 2.45 GHz, 2.5 kW electron cyclotron heating (ECH), whereas diagnostics are carried out with a lower power (10 W) separate frequency (1-2.1 GHz) microwave. Three components, i.e., two electromagnetic (toroidal and poloidal directions) and an electrostatic (if refractive index is sufficiently higher than unity, it corresponds to radial component), of ECRF electric field are simultaneously measured with three probing antennas, which are inserted into plasma. Selectivities of each component signal were checked experimentally. Excitation antennas have quite high selectivity of direction of linear polarization. As probing antennas for detecting electromagnetic components, we employed a monopole antenna with a length of 35 mm, and the separation of the poloidal (O-wave) and toroidal (X-wave) components of ECRF electric field could be available with this antenna. To detect EBW, which is an electrostatic wave, a small tip (1 mm) antenna was used. As the preliminary results, we detected signals that have three characteristics of EBW, i.e., short wavelength, backward propagation, and electrostatic.

  7. Active core profile and transport modification by application of Ion Bernstein Wave power in PBX-M

    International Nuclear Information System (INIS)

    Application of Ion Bernstein Wave Heating (IBWH) into the Princeton Beta Experiment-Modification (PBX-M) tokamak stabilizes sawtooth oscillations and generates peaked density profiles. A transport barrier, spatially correlated with the IBWH power deposition profile, is observed in the core of IBWH assisted neutral beam injection (NBI) discharges. A precursor to the fully developed barrier is seen in the soft x-ray data during edge localized mode (ELM) activity. Sustained IBWH operation is conducive to a regime where the barrier supports large triangledown ne, triangledown Te, triangledown vphi, and triangledown Ti, delimiting the confinement zone. This regime is reminiscent of the H(high)-mode but with a confinement zone moved inwards. The core region has better than H-mode confinement while the peripheral region is L(low)-mode-like. The peaked profile enhanced NBI core deposition and increases nuclear reactivity. An increase in central Ti results from χi reduction (compared to H-mode) and better beam penetration. Bootstrap current fractions of up to 0.32--0.35 locally and 0.28 overall were obtained when an additional NBI burst is applied to this plasma

  8. Possibility of using ion-Bernstein waves for alpha power extraction in tokamaks

    International Nuclear Information System (INIS)

    If the fusion α-particle power is directly channeled to do useful things rather than simply undergo collisional absorption, there is an opportunity for significantly improved tokamak reactor performance. In the absence of the channeling, the α-particle power results predominantly in electron heating, which is a poor use of this power. One possibility is to direct this power into waves that damp on electrons traveling in one direction to sustain the plasma current. Since the power required to drive the toroidal current is about 10% of the fusion power output, whereas the α-particle power is 20% of the fusion power output, using even a fraction of the α-particle power to amplify the waves used for current drive can result in very significant savings in the required power for the current drive. A second possibility is to direct this power into waves that damp on fuel ions to increase the plasma reactivity. Such a channeling of the α-particle power could make possible the operation of fusion reactors in regimes in which the fuel ion temperature can be much greater than the electron temperature. It may also be possible to sustain a hot, nonmaxwellian component of the fuel ions, further enhancing the reactivity. By these means, if 75% of the α-particle power is diverted, the plasma reactivity, at constant pressure, can be increased by about a factor of two. It may even be possible to achieve at once the increased reactivity and the current drive, if, for example the α-particle power is channeled into waves that damp on fast ions traveling in one toroidal direction. (author) 10 refs., 4 figs

  9. Electron Bernstein Wave Heating and Electron Cyclotron Current Drive by Use of Upgraded ECH System in LHD

    International Nuclear Information System (INIS)

    Full text: In LHD, electron Bernstein wave (EBW) heating was successfully demonstrated by two ways of mode conversion to EBWs from injected EC-waves, by so-called slow-XB and OXB techniques. To realize the excitation of EBWs by the slow-XB technique, EC-waves in X-mode polarization should be injected to plasmas from high magnetic field side (HFS). In LHD, newly installed inner-vessel mirror close to a helical coil is used for the HFS injection. Evident increases in Te at the plasma core region and Wp were caused by the HFS injection with 0.18 s pulse width to a plasma with ne(0) of 24 x 1019 m-3, that is, 3.3 times higher than the plasma cut-off density for O-mode waves, and 1.6 x higher than the left-hand cut-off density of 14.7 x 1019 m-3 for slow-X-mode waves. Thus, the heating effects especially the increase in Te at the plasma core region should be attributed to the mode-converted EBWs, not to the X- or O-mode waves. For excitation of EBWs by the OXB technique, O-mode waves should be injected from the low magnetic filed side toward the so-called 'mode conversion window' . Two pulses of 77 GHz, 1.05 MW EC-wave (0.1 s pulse width each with a 0.1 s interval) in O-mode polarization were injected to an NB-sustained plasma, aiming at the mode conversion window calculated in advance. With both of the two ECH pulses, increases in Wp and mitigations of decreasing trend in Te measured with ECE are recognized. The line average electron density continuously increased during the ECH pulse injection. At the start timing of the 1st pulse, ne(0) was equal to the O-mode cut-off density, 7.35 x 1019 m-3, and ne(0) gradually increased to 7.7 x 1019 m-3 at the end of the 2nd pulse. The heating efficiency Pabs/Pech is evaluated as ∼ 15%. Using the high-power, long-pulse 77 GHz ECH system, 2nd harmonic on-axis ECCD experiments with 775 kW injection power and the line average electron density of 0.3 x 1019 m-3 were conducted. At optimum beam directions, maximum EC-driven currents

  10. THz wave emission microscope

    Science.gov (United States)

    Yuan, Tao

    Sensing and imaging using Terahertz (THz) radiation has attracted more and more interest in the last two decades thanks to the abundant material 'finger prints' in the THz frequency range. The low photon energy also makes THz radiation an attractive tool for nondestructive evaluation of materials and devices, biomedical applications, security checks and explosive screening. Due to the long wavelength, the far-field THz wave optical systems have relatively low spatial resolution. This physical limitation confines THz wave sensing and imaging to mostly macro-size samples. To investigate local material properties or micro-size structures and devices, near-field technology has to be employed. In this dissertation, the Electro-Optical THz wave emission microscope is investigated. The basic principle is to focus the femtosecond laser to a tight spot on a thin THz emitter layer to produce a THz wave source with a similar size as the focus spot. The apparatus provides a method for placing a THz source with sub-wavelength dimension in the near-field range of the investigated sample. Spatial resolution to the order of one tenth of the THz wavelength is demonstrated by this method. The properties of some widely used THz wave emission materials under tight focused pump light are studied. As an important branch of THz time domain spectroscopy (THz-TDS), THz wave emission spectroscopy has been widely used as a tool to investigate the material physics, such as energy band structure, carrier dynamics, material nonlinear properties and dynamics. As the main work of this dissertation, we propose to combine the THz wave emission spectroscopy with scanning probe microscopy (SPM) to build a tip-assisted THz wave emission microscope (TATEM), which is a valuable extension to current SPM science and technology. Illuminated by a femtosecond laser, the biased SPM tip forms a THz wave source inside the sample beneath the tip. The source size is proportional to the apex size of the tip so

  11. Bernstein polynomials on Simplex

    OpenAIRE

    Bayad, A.; Kim, T.; Rim, S. -H.

    2011-01-01

    We prove two identities for multivariate Bernstein polynomials on simplex, which are considered on a pointwise. In this paper, we study good approximations of Bernstein polynomials for every continuous functions on simplex and the higher dimensional q-analogues of Bernstein polynomials on simplex

  12. Variational Symplectic Particle-in-cell Simulation of Nonlinear Mode Conversion from Extraordinary waves to Bernstein Waves

    OpenAIRE

    Xiao, Jianyuan; Liu, Jian; Qin, Hong; Yu, Zhi; Xiang, Nong

    2015-01-01

    In this paper, the nonlinear mode conversion of extraordinary waves in nonuniform magnetized plasmas is studied using the variational symplectic particle-in-cell simulation. The accuracy of the nonlinear simulation is guaranteed by the long-term accuracy and conservativeness of the symplectic algorithm. The spectra of the electromagnetic wave, the evolution of the wave reflectivity, the energy deposition profile, and the parameter-dependent properties of radio-frequency waves during the nonli...

  13. Influence of Bernstein modes on the efficiency of electron cyclotron resonance x-ray source

    International Nuclear Information System (INIS)

    The article considers the factors influencing the temperature of hot electron component in an electron cyclotron resonance (ECR) x-ray source. In such sources the electron heating occurs often due to extraordinary electromagnetic wave propagating perpendicularly to the magnetic field. In this case the possibility of the absorption of Bernstein modes is regarded as an additional mechanism of electron heating. The Bernstein modes in an ECR x-ray source can arise due to either linear transformation or parametric instability of external transversal wave. The article briefly reviews also the further experiments which will be carried out to study the influence of Bernstein modes on the increase of hot electron temperature and consequently of x-ray emission

  14. ITER Plasma at Ion Cyclotron Frequency Domain: The Fusion Alpha Particles Diagnostics Based on the Stimulated Raman Scattering of Fast Magnetosonic Wave off High Harmonic Ion Bernstein Modes

    Science.gov (United States)

    Stefan, V. Alexander

    2014-10-01

    A novel method for alpha particle diagnostics is proposed. The theory of stimulated Raman scattering, SRS, of the fast wave and ion Bernstein mode, IBM, turbulence in multi-ion species plasmas, (Stefan University Press, La Jolla, CA, 2008). is utilized for the diagnostics of fast ions, (4)He (+2), in ITER plasmas. Nonlinear Landau damping of the IBM on fast ions near the plasma edge leads to the space-time changes in the turbulence level, (inverse alpha particle channeling). The space-time monitoring of the IBM turbulence via the SRS techniques may prove efficient for the real time study of the fast ion velocity distribution function, spatial distribution, and transport. Supported by Nikola Tesla Labs., La Jolla, CA 92037.

  15. Bernstein functions theory and applications

    CERN Document Server

    Schilling, René L; Vondracek, Zoran

    2010-01-01

    This text is a self-contained and unified approach to Bernstein functions and their subclasses, bringing together old and establishing new connections. Applications of Bernstein functions in different fields of mathematics are given, with special attention to interpretations in probability theory. An extensive list of complete Bernstein functions with their representations is provided.

  16. Electron cyclotron-electron Bernstein wave emission diagnostics for the COMPASS tokamak

    Czech Academy of Sciences Publication Activity Database

    Zajac, Jaromír; Preinhaelter, Josef; Urban, Jakub; Žáček, František; Šesták, David; Nanobashvili, S.

    2010-01-01

    Roč. 81, č. 10 (2010), 10D911-10D911. ISSN 0034-6748. [TOPICAL CONFERENCE ON HIGH-TEMPERATURE PLASMA DIAGNOSTICS/18th./. Wildwood, New Jersey, 16.05.2010-20.05.2010] R&D Projects: GA ČR GA202/08/0419 Institutional research plan: CEZ:AV0Z20430508 Keywords : antenna radiation patterns * antennas in plasma * plasma diagnostics * Tokamak Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.598, year: 2010 http://link.aip.org/link/?RSI/81/10D911

  17. Magnetohydrodynamic behaviour during core transport barrier experiments with ion Bernstein wave heating in PBX-M: I ELMs, fluctuations and crash events

    Science.gov (United States)

    Sesnic, S.; Kaita, R.; Batha, S. H.; Bell, R. E.; Bernabei, S.; Chance, M. S.; DeLa Luna, E.; Dunlap, J. L.; England, A. C.; Isler, R. C.; Jones, S.; Kaye, S. M.; Kesner, J.; Kugel, H. W.; LeBlanc, B.; Levinton, F. M.; Luckhardt, S. C.; Manickam, J.; Okabayashi, M.; Ono, M.; Paoletti, F.; Paul, S. F.; Post-Zwicker, A. P.; Sanchez Sanz, J.; Sauthoff, N. R.; Seki, T.; Takahashi, H.; Tighe, W.; Von Goeler, S.; Woskov, P.; Zolfaghari, A.

    1998-06-01

    If the ion Bernstein wave (IBW) heating power in an H mode discharge of the PBX-M experiment exceeds a threshold power of about 200 kW, a core transport barrier is created in the central region of the plasma. At lower neutral beam injection (NBI) powers, the core barrier is accompanied by an edge L mode. The high edge localized mode (ELM) repetition frequency (1 kHz) prevents the creation of a strong barrier, so the edge first has to make an H-to-L transition before a strong core transport barrier can be created. At higher NBI powers, the ELM repetition frequency is lowered to less than 200 Hz, which allows the immediate creation of a strong core barrier. Edge localized mode loss, which propagates radially first on a fast (non-diffusive) and then on a slow (diffusive) time-scale all the way to the plasma core, is strongly reduced in the core barrier region. Correlated with the reduced ELM loss, the fluctuations in the core barrier region are also strongly reduced, both during the ELM and during the quiet periods between the ELMs. There is strong evidence that the IBW induced poloidal flow shear is responsible for the stabilization of core turbulence and the creation of the core transport barrier. The large perpendicular E × B flow shear component of the measured toroidal velocity in co-injection neutral beam heated discharges seems to be largely cancelled by the ion diamagnetic drift shear produced by large ion pressure gradients in the core barrier region. The value of IBW induced poloidal flow has not been experimentally determined, but its numerical value is found to be a factor of 4 larger than either the toroidal velocity or the ion diamagnetic drift shear components, leaving only IBW induced flow shear as the most probable cause for the turbulence stabilization. The core turbulence suppression and the creation of the core transport barrier is also consistent with expectations from a comparison between the E × B flow shear rate and a rough estimate of the

  18. Magnetohydrodynamic behaviour during core transport barrier experiments with ion Bernstein wave heating in PBX-M: I ELMs fluctuations and crash events

    International Nuclear Information System (INIS)

    If the ion Bernstein wave (IBW) heating power in an H mode discharge of the PBX-M experiment exceeds a threshold power of about 200 kW, a core transport barrier is created in the central region of the plasma. At lower neutral beam injection (NBI) powers, the core barrier is accompanied by an edge L mode. The high edge localized mode (ELM) repetition frequency (1 kHz) prevents the creation of a strong barrier, so the edge first has to make an H-to-L transition before a strong core transport barrier can be created. At higher NBI powers, the ELM repetition frequency is lowered to less than 200 Hz, which allows the immediate creation of a strong core barrier. Edge localized mode loss, which propagates radially first on a fast (non-diffusive) and then on a slow (diffusive) time-scale all the way to the plasma core, is strongly reduced in the core barrier region. Correlated with the reduced ELM loss, the fluctuations in the core barrier region are also strongly reduced, both during the ELM and during the quite periods between the ELMs. There is strong evidence that the IBW induced poloidal flow shear is responsible for the stabilization of core turbulence and the creation of the core transport barrier. The large perpendicular E x B flow shear component of the measured toroidal velocity in co-injection neutral beam heated discharges seems to be largely cancelled by the ion diamagnetic drift shear produced by large ion pressure gradients in the core barrier region. The value of IBW induced poloidal flow has not been experimentally determined, but its numerical value is found to be a factor of 4 larger than either the toroidal velocity or the ion diamagnetic drift shear components, leaving only IBW induced flow shear as the most probable cause for the turbulence stabilization. The core turbulence suppression and the creation of the core transport barrier is also consistent with expectations from a comparison between the E x B flow shear rate and a rough estimate of the

  19. Stimulated Electromagnetic Emission Indicator of Glow Plasma Discharges from Ionospheric HF Wave Transmissions with HAARP

    Science.gov (United States)

    Bernhardt, P. A.; Scales, W.; Briczinski, S. J.; Fu, H.; Mahmoudian, A.; Samimi, A.

    2012-12-01

    High power radio waves resonantly interact with to accelerate electrons for production of artificial aurora and plasma clouds. These plasma clouds are formed when the HF frequency is tuned near a harmonic of the electron cyclotron frequency. At a narrow band resonance, large electrostatic fields are produced below the F-layer and the neutral atmosphere breaks down with a glow plasma discharge. The conditions for this resonance are given by matching the pump wave frequency and wave-number with the sum of daughter frequencies and wave-numbers for several plasma modes. The most likely plasma mode that accelerates the electrons is the electron Bernstein wave in conjunction with an ion acoustic wave. Both upper hybrid and whistler mode waves are also possible sources of electron acceleration. To determine the plasma process for electron acceleration, stimulated electromagnetic emissions are measured using ground receivers in a north-south chain from the HAARP site. Recent observations have shown that broad band spectral lines downshifted from the HF pump frequency are observed when artificial plasma clouds are formed. For HF transmissions are the 2nd, 3rd, and 4th gyro harmonic, the downshifted indicators are found 500 Hz, 20 kHz, and 140 kHz, respectively, from the pump frequency. This Indicator Mode (IM) anticipates that a plasma layer will be formed before it is recorded with an ionosonde or optical imager.

  20. Stimulated Brillouin scatter and stimulated ion Bernstein scatter during electron gyroharmonic heating experiments

    Science.gov (United States)

    Fu, H.; Scales, W. A.; Bernhardt, P. A.; Samimi, A.; Mahmoudian, A.; Briczinski, S. J.; McCarrick, M. J.

    2013-09-01

    Results of secondary radiation, Stimulated Electromagnetic Emission (SEE), produced during ionospheric modification experiments using ground-based high-power radio waves are reported. These results obtained at the High Frequency Active Auroral Research Program (HAARP) facility specifically considered the generation of Magnetized Stimulated Brillouin Scatter (MSBS) and Stimulated Ion Bernstein Scatter (SIBS) lines in the SEE spectrum when the transmitter frequency is near harmonics of the electron gyrofrequency. The heater antenna beam angle effect was investigated on MSBS in detail and shows a new spectral line postulated to be generated near the upper hybrid resonance region due to ion acoustic wave interaction. Frequency sweeping experiments near the electron gyroharmonics show for the first time the transition from MSBS to SIBS lines as the heater pump frequency approaches the gyroharmonic. Significantly far from the gyroharmonic, MSBS lines dominate, while close to the gyroharmonic, SIBS lines strengthen while MSBS lines weaken. New possibilities for diagnostic information are discussed in light of these new observations.

  1. Simulation study of Bernstein modes

    International Nuclear Information System (INIS)

    The properties of Bernstein modes were investigated through computer simulations using two-dimensional and two-and-one-half-dimensional (i.e., two spatial and three velocity coordinates) electrostatic models with fixed magnetic field. The measured discrete spectrum was found to agree with the linear dispersion relation for these modes. The quasi-periodic phenomenon of early phase-mixing damping and later recurrence, predicted by Baldwin and Rowlands, was observed. For large wavenumber k/sub perpendicular/, the initial damping rate is the same as that for Landau damping in an unmagnetized plasma; for small k/sub perpendicular/, however, it is much stronger. The recurrence peaks slowly damp in time at a rate proportional to k2/sub perpendicular/D, where D is the measured cross-field particle diffusion coefficient which is dominated by convective transport. Finally, splitting of the main spectral peaks and the appearance of subpeaks at half-integral multiples of the cyclotron frequency are observed and may be explained by nonlinear mode coupling

  2. Roles Played by Electrostatic Waves in Producing Radio Emissions

    Science.gov (United States)

    Cairns, Iver H.

    2000-01-01

    Processes in which electromagnetic radiation is produced directly or indirectly via intermediate waves are reviewed. It is shown that strict theoretical constraints exist for electrons to produce nonthermal levels of radiation directly by the Cerenkov or cyclotron resonances. In contrast, indirect emission processes in which intermediary plasma waves are converted into radiation are often favored on general and specific grounds. Four classes of mechanisms involving the conversion of electrostatic waves into radiation are linear mode conversion, hybrid linear/nonlinear mechanisms, nonlinear wave-wave and wave-particle processes, and radiation from localized wave packets. These processes are reviewed theoretically and observational evidence summarized for their occurrence. Strong evidence exists that specific nonlinear wave processes and mode conversion can explain quantitatively phenomena involving type III solar radio bursts and ionospheric emissions. On the other hand, no convincing evidence exists that magnetospheric continuum radiation is produced by mode conversion instead of nonlinear wave processes. Further research on these processes is needed.

  3. Understanding the growth rate patterns of ion Bernstein instabilities driven by ring-like proton velocity distributions

    Science.gov (United States)

    Min, Kyungguk; Liu, Kaijun

    2016-04-01

    Fast magnetosonic waves in Earth's inner magnetosphere, which have as their source ion Bernstein instabilities, are driven by hot proton velocity distributions (fp) with ∂fp(v⊥)/∂v⊥>0. Two typical types of distributions with such features are ring and shell velocity distributions. Both have been used in studies of ion Bernstein instabilities and fast magnetosonic waves, but the differences between instabilities driven by the two types of distributions have not been thoroughly addressed. The present study uses linear kinetic theory to examine and understand these differences. It is found that the growth rate pattern is primarily determined by the cyclotron resonance condition and the structure of the velocity distribution in gyroaveraged velocity space. For ring-driven Bernstein instabilities, as the parallel wave number (k∥) increases, the discrete unstable modes approximately follow the corresponding proton cyclotron harmonic frequencies while they become broader in frequency space. At sufficiently large k∥, the neighboring discrete modes merge into a continuum. In contrast, for shell-driven Bernstein instabilities, the curved geometry of the shell velocity distribution in gyroaveraged velocity space results in a complex alternating pattern of growth and damping rates in frequency and wave number space and confines the unstable Bernstein modes to relatively small k∥. In addition, when k∥ increases, the unstable modes are no longer limited to the proton cyclotron harmonic frequencies. The local growth rate peak near an exact harmonic at small k∥ bifurcates into two local peaks on both sides of the harmonic when k∥ becomes large.

  4. Spontaneous emission of non-dispersive Rydberg wave packets

    OpenAIRE

    Delande, Dominique; Zakrzewski, Jakub

    1998-01-01

    Non dispersive electronic Rydberg wave packets may be created in atoms illuminated by a microwave field of circular polarization. We discuss the spontaneous emission from such states and show that the elastic incoherent component (occuring at the frequency of the driving field) dominates the spectrum in the semiclassical limit, contrary to earlier predictions. We calculate the frequencies of single photon emissions and the associated rates in the "harmonic approximation", i.e. when the wave p...

  5. Excitation of Alfven Waves and Pulsar Radio Emission

    OpenAIRE

    Lyutikov, Maxim

    1999-01-01

    We analyze mechanisms of the excitation of Alfv\\'{e}n wave in pulsar magnetospheres as a possible source of pulsar radio emission generation. We find that Cherenkov excitation of obliquely propagating Alfv\\'{e}n waves is inefficient, while excitation at the anomalous cyclotron resonance by the particles from the primary beam and from the tail of the bulk distribution function may have a considerable growth rate. The cyclotron instability on Alfv\\'{e}n waves occurs in the kinetic regime still ...

  6. Defect effects on THz wave emission induced by ion irradiation

    International Nuclear Information System (INIS)

    Background: As the core component of terahertz system, terahertz source determines the performance of the whole system. The THz wave emission efficiency depends decisively on the THz emitting materials which are usually made of low-temperature-grown gallium arsenide. It is found that through ion irradiation better THz wave emission material can be prepared, which overcomes the poor reproducibility of high quality material prepared by the traditional method. Purpose: In order to find out the best irradiation condition for producing the required photoconductive material, we try to clarify the mechanism of the THz wave emission induced by ion implantation. Methods: Applying Monte Carlo method, we simulated the terahertz emission under different defect conditions, and tested the emission efficiency of GaAs and InP(Fe) irradiated by N ions with the energy of 500 keV and 1.5 MeV, respectively. Results: MC simulation study shows that both capture cross-section and trap density can cause changes in terahertz pulse width and peak intensity. From the experiments conducted on ion irradiated semiconductors we found only the peak intensity changes with the irradiation fluence. Conclusion: It is proposed that intrinsic defects introduced during growth of crystals are the key defects that contribute mainly to the terahertz wave emission behavior, and defects introduced by ion irradiation may only modify the transport property of carriers through scattering in semiconductor, by which it changes the terahertz wave emission performance. (authors)

  7. One-D full-wave description of plasma emission and absorption in the ion cyclotron range of frequency in tokamaks

    International Nuclear Information System (INIS)

    To maintain the ignition state in a tokamak fusion reactor, a control must be performed on the population of alpha-products, and this implies the ability to diagnose those α-particles. It is studied here whether the detection of emission radiated in the ion cyclotron range of frequency be a reactor plasma can provide useful information concerning fusion products, especially concerning their density profile. It is shown that the detection of the radiation emitted by the fast alpha particles along their cyclotron motion can give access to moments of their distribution function. This requires to compute the phase of the emitted field, using a full-wave approach. Such a technique allows to set in a convenient way the inverse problem of the determination of the emitting α-particles distribution through the radiation detection. A brief analysis of the expected situation in a reactor-relevant plasma is given. In parallel, the 1-D full-wave code developed in this frame is also useful for studying the physics of Fast Wave plasma heating. It enables to take into account the mode conversion of the Fast Wave into the Ion Bernstein Wave that appears near each ion cyclotron resonance. Results show that higher order terms may significantly alter the energy partitioning, in hot plasma cases involving mode conversion heating and/or ion cyclotron high harmonics heating. (author)

  8. One-D full-wave description of plasma emission and absorption in the ion cyclotron range of frequency in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Fraboulet, D.; Becoulet, A.; Nguyen, F

    1998-11-01

    To maintain the ignition state in a tokamak fusion reactor, a control must be performed on the population of alpha-products, and this implies the ability to diagnose those {alpha}-particles. It is studied here whether the detection of emission radiated in the ion cyclotron range of frequency be a reactor plasma can provide useful information concerning fusion products, especially concerning their density profile. It is shown that the detection of the radiation emitted by the fast alpha particles along their cyclotron motion can give access to moments of their distribution function. This requires to compute the phase of the emitted field, using a full-wave approach. Such a technique allows to set in a convenient way the inverse problem of the determination of the emitting {alpha}-particles distribution through the radiation detection. A brief analysis of the expected situation in a reactor-relevant plasma is given. In parallel, the 1-D full-wave code developed in this frame is also useful for studying the physics of Fast Wave plasma heating. It enables to take into account the mode conversion of the Fast Wave into the Ion Bernstein Wave that appears near each ion cyclotron resonance. Results show that higher order terms may significantly alter the energy partitioning, in hot plasma cases involving mode conversion heating and/or ion cyclotron high harmonics heating. (author) 47 refs.

  9. MILLIMETER-WAVE EMISSIVITY OF CELLULAR SYSTEMS

    Science.gov (United States)

    A general analysis has been presented of the millimeter-wave and farinfrared spectroscopic properties of in vivo cellular systems, and of the boson radiative equilibrium with steady-state nonequilibrium molecular systems. The frequency threshhold of spectroscopic properties assoc...

  10. Theories of radio emissions and plasma waves. [in Jupiter magnetosphere

    Science.gov (United States)

    Goldstein, M. L.; Goertz, C. K.

    1983-01-01

    The complex region of Jupiter's radio emissions at decameter wavelengths, the so-called DAM, is considered, taking into account the basic theoretical ideas which underly both the older and newer theories and models. Linear theories are examined, giving attention to direct emission mechanisms, parallel propagation, perpendicular propagation, and indirect emission mechanisms. An investigation of nonlinear theories is also conducted. Three-wave interactions are discussed along with decay instabilities, and three-wave up-conversio. Aspects of the Io and plasma torus interaction are studied, and a mechanism by which Io can accelerate electrons is reviewed.

  11. Resonant X-ray emission with a standing wave excitation.

    Science.gov (United States)

    Ruotsalainen, Kari O; Honkanen, Ari-Pekka; Collins, Stephen P; Monaco, Giulio; Moretti Sala, Marco; Krisch, Michael; Hämäläinen, Keijo; Hakala, Mikko; Huotari, Simo

    2016-01-01

    The Borrmann effect is the anomalous transmission of x-rays in perfect crystals under diffraction conditions. It arises from the interference of the incident and diffracted waves, which creates a standing wave with nodes at strongly absorbing atoms. Dipolar absorption of x-rays is thus diminished, which makes the crystal nearly transparent for certain x-ray wave vectors. Indeed, a relative enhancement of electric quadrupole absorption via the Borrmann effect has been demonstrated recently. Here we show that the Borrmann effect has a significantly larger impact on resonant x-ray emission than is observable in x-ray absorption. Emission from a dipole forbidden intermediate state may even dominate the corresponding x-ray spectra. Our work extends the domain of x-ray standing wave methods to resonant x-ray emission spectroscopy and provides means for novel spectroscopic experiments in d- and f-electron systems. PMID:26935531

  12. Resonant X-ray emission with a standing wave excitation

    Science.gov (United States)

    Ruotsalainen, Kari O.; Honkanen, Ari-Pekka; Collins, Stephen P.; Monaco, Giulio; Moretti Sala, Marco; Krisch, Michael; Hämäläinen, Keijo; Hakala, Mikko; Huotari, Simo

    2016-01-01

    The Borrmann effect is the anomalous transmission of x-rays in perfect crystals under diffraction conditions. It arises from the interference of the incident and diffracted waves, which creates a standing wave with nodes at strongly absorbing atoms. Dipolar absorption of x-rays is thus diminished, which makes the crystal nearly transparent for certain x-ray wave vectors. Indeed, a relative enhancement of electric quadrupole absorption via the Borrmann effect has been demonstrated recently. Here we show that the Borrmann effect has a significantly larger impact on resonant x-ray emission than is observable in x-ray absorption. Emission from a dipole forbidden intermediate state may even dominate the corresponding x-ray spectra. Our work extends the domain of x-ray standing wave methods to resonant x-ray emission spectroscopy and provides means for novel spectroscopic experiments in d- and f-electron systems. PMID:26935531

  13. Excitation threshold of Stimulated Electromagnetic Emissions SEEs generated at pump frequency near the third electron gyroharmonic

    Science.gov (United States)

    Mahmoudian, A.; Bernhardt, P. A.; Scales, W.

    2012-12-01

    The High-Frequency Active Auroral Research Program (HAARP) in Gakona, Alaska provides effective radiated powers in the megawatt range that have allowed researchers to study many non-linear effects of wave-plasma interactions. Stimulated Electromagnetic Emission (SEE) is of interest to the ionospheric community for its diagnostic purposes. In recent HAARP heating experiments, it has been shown that during the Magnetized Stimulated Brillouin Scattering MSBS instability, the pumped electromagnetic wave may decay into an electromagnetic wave and a low frequency electrostatic wave (either ion acoustic IA wave or electrostatic ion cyclotron EIC wave). Using Stimulated Electromagnetic Emission (SEE) spectral features, side bands which extend above and below the pump frequency can yield significant diagnostics for the modified ionosphere. It has been shown that the IA wave frequency offsets can be used to measure electron temperature in the heated ionosphere and EIC wave offsets can be used as a sensitive method to determine the ion species by measuring ion mass using the ion gyro-frequency offset. The threshold of each emission line has been measured by changing the amplitude of pump wave. The experimental results aimed to show the threshold for transmitter power to excite IA wave propagating along the magnetic field lines as well as for EIC wave excited at an oblique angle relative to the background magnetic field. Another parametric decay instability studied is the ion Bernstein decay instability that has been attributed to the simultaneous parametric decay of electron Bernstein waves into multiple electron Bernstein and ion Bernstein waves. The SIB process is thought to involve mode conversion from EM to EB waves followed by parametric decay of the EB wave to multiple EB and IB waves. The parametric decay instability of ion Bernstein modes has been observed simultaneously for the first time at the third electron gyroharmonics during 2011 Summer Student Research

  14. CONVERGENCE ARTE FOR INTERATES OF q-BERNSTEIN POLYNOMIALS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Recently, q-Bernstein polynomials have been intensively investigated by a number of authors. Their results show that for q ≠ 1, q-Bernstein polynomials possess of many interesting properties. In this paper, the convergence rate for iterates of both q-Bernstein when n →∞ and convergence rate of Bn(f,q;x) when f ∈ Cn-1[0, 1], q →∞ are also presented.

  15. Nonlinear dynamics of Airy-Vortex 3D wave packets: Emission of vortex light waves

    CERN Document Server

    Driben, Rodislav

    2014-01-01

    The dynamics of 3D Airy-vortex wave packets is studied under the action of strong self-focusing Kerr nonlinearity. Emissions of nonlinear 3D waves out of the main wave packets with the topological charges were demonstrated. Due to the conservation of the total angular momentum, charges of the emitted waves are equal to those carried by the parental light structure. The rapid collapse imposes a severe limitation on the propagation of multidimensional waves in Kerr media. However, the structure of the Airy beam carrier allows the coupling of light from the leading, most intense peak into neighboring peaks and consequently strongly postpones the collapse. The dependence of the critical input amplitude for the appearance of a fast collapse on the beam width is studied for wave packets with zero and non-zero topological charges. Wave packets carrying angular momentum are found to be much more resistant to the rapid collapse, especially those having small width.

  16. Simulation of the time development of EBW emission from NSTX

    Czech Academy of Sciences Publication Activity Database

    Preinhaelter, Josef; Urban, Jakub; Taylor, G.; Diem, S.; Vahala, L.; Vahala, G.

    2006-01-01

    Roč. 51, č. 4 (2006), K1.00024. ISSN 0003-0503. [International Sherwood Fusion Theory Conference/2006./. Dallas, Texas, 22.4.2006-25.4.2006] Institutional research plan: CEZ:AV0Z20430508 Keywords : Conversion * Emission * Tokamaks * Electron Bernstein waves * Simulation * MAST * NSTX Subject RIV: BL - Plasma and Gas Discharge Physics http://www.aps.org/meet/APR06/baps/all_APR06.pdf http://meetings.aps.org/Meeting/APR06/Event/47670

  17. Bernstein's Lethargy Theorem in Frechet Spaces

    OpenAIRE

    Aksoy, Asuman Guven; Lewicki, Grzegorz

    2015-01-01

    In this paper we consider Bernstein's Lethargy Theorem (BLT) in the context of Fr\\'{e}chet spaces. Let $X$ be an infinite-dimensional Fr\\'echet space and let $\\mathcal{V}=\\{V_n\\}$ be a nested sequence of subspaces of $ X$ such that $ \\bar{V_n} \\subseteq V_{n+1}$ for any $ n \\in \\mathbb{N}$ and $ X=\\bar{\\bigcup_{n=1}^{\\infty}V_n}.$ Let $ e_n$ be a decreasing sequence of positive numbers tending to 0. Under an additional natural condition on $\\sup\\{\\{dist}(x, V_n)\\}$, we prove that there exists...

  18. Deformations of Accreting Neutron Star Crusts and Gravitational Wave Emission

    OpenAIRE

    Ushomirsky, Greg; Cutler, Curt; Bildsten, Lars

    2000-01-01

    Motivated by the narrow range of spin frequencies of nearly 20 accreting neutron stars, Bildsten (1998) conjectured that their spin-up had been halted by the emission of gravitational waves. He also pointed out that small nonaxisymmetric temperature variations in the accreted crust will lead to "wavy" electron capture layers, whose horizontal density variations naturally create a mass quadrupole moment. We present a full calculation of the crust's elastic adjustment to these density perturbat...

  19. MULTIVARIATE WEIGHTED BERNSTEIN-TYPE INEQUALITY AND ITS APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    Cao Feilong; Lin Shaobo

    2012-01-01

    Bernstein inequality played an important role in approximation theory and Fourier analysis.This article first introduces a general system of functions and the socalled multivariate weighted Bernstein,Nikol'skiǐ,and Ul'yanov-type inequalities.Then,the relations among these three inequalities are discussed.Namely,it is proved that a family of functions equipped with Bernstein-type inequality satisfies Nikol'skiǐ-type and Ul'yanov-type inequality.Finally,as applications,some classical inequalities are deduced from the obtained results.

  20. Generalized -Bernstein-Schurer Operators and Some Approximation Theorems

    Directory of Open Access Journals (Sweden)

    M. Mursaleen

    2013-01-01

    Full Text Available We study statistical approximation properties of -Bernstein-Shurer operators and establish some direct theorems. Furthermore, we compute error estimation and show graphically the convergence for a function by operators and give its algorithm.

  1. Emission of Alfven Waves by Planets in Close Orbits

    Science.gov (United States)

    MacGregor, Keith B.; Pinsonneault, M. H.

    2011-01-01

    We examine the electrodynamics of a conducting planet orbiting within a magnetized wind that emanates from its parent star. When the orbital motion differs from corotation with the star, an electric field exists in the rest frame of the planet, inducing a charge separation in its ionosphere. Because the planet is immersed in a plasma, this charge can flow away from it along the stellar magnetic field lines it successively contacts in its orbit. For sufficiently rapid orbital motion, a current system can be formed that is closed by Alfvenic disturbances that propagate along field lines away from the planet. Using a simple model for the wind from a Sun-like star, we survey the conditions under which Alfven wave emission can occur, and estimate the power radiated in the form of linear waves for a range of stellar, planetary, and wind properties. For a Jupiter-like planet in a close (a type star, the emitted wave power can be as large as 1027 erg/s. While only a small influence on the planet's orbit, a wave power of this magnitude may have consequences for wind dynamics and localized heating of the stellar atmosphere. NCAR is sponsored by the NSF.

  2. Upper limits on gravitational wave emission from 78 radio pulsars

    CERN Document Server

    Abbott, B; Adhikari, R; Agresti, J; Ajith, P; Allen, B; Amin, R; Anderson, S B; Anderson, W G; Arain, M; Araya, M; Armandula, H; Ashley, M; Aston, S; Aufmuth, P; Aulbert, C; Babak, S; Ballmer, S; Bantilan, H; Barish, B C; Barker, C; Barker, D; Barr, B; Barriga, P; Barton, M; Bayer, K; Betzwieser, J; Beyersdorf, P T; Bhawal, B; Bilenko, I A; Billingsley, G; Biswas, R; Black, E; Blackburn, K; Blackburn, L; Blair, D; Bland, B; Bogenstahl, J; Bogue, L; Bork, R; Boschi, V; Bose, S; Brady, P R; Braginsky, V B; Brau, J E; Brinkmann, M; Brooks, A; Brown, D A; Bullington, A; Bunkowski, A; Buonanno, A; Burmeister, O; Busby, D; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cannizzo, J; Cannon, K; Cantley, C A; Cao, J; Cardenas, L; Castaldi, G; Cepeda, C; Chalkey, E; Charlton, P; Chatterji, S; Chelkowski, S; Chen, Y; Chiadini, F; Christensen, N; Clark, J; Cochrane, P; Cokelaer, T; Coldwell, R; Conte, R; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Croce, R P; Crooks, D R M; Cruise, A M; Cumming, A; D'Ambrosio, E; Dalrymple, J; Danzmann, K; Davies, G; De Bra, D; DeSalvo, R; Degallaix, J; Degree, M; Demma, T; Dergachev, V; Desai, S; Dhurandhar, S V; Di Credico, A; Dickson, J; Diederichs, G; Dietz, A; Doomes, E E; Drever, R W P; Dumas, J C; Dupuis, R J; Dwyer, J G; Díaz, M; Ehrens, P; Espinoza, E; Etzel, T; Evans, M; Evans, T; Fairhurst, S; Fan, Y; Fazi, D; Fejer, M M; Finn, L S; Fiumara, V; Fotopoulos, N; Franzen, A; Franzen, K Y; Freise, A; Frey, R E; Fricke, T; Fritschel, P; Frolov, V V; Fyffe, M; Galdi, V; Garofoli, J; Gholami, I; Giaime, J A; Giampanis, S; Giardina, K D; Goda, K; Goetz, E; Goggin, L; González, G; Gossler, S; Grant, A; Gras, S; Gray, C; Gray, M; Greenhalgh, J; Gretarsson, A M; Grosso, R; Grote, H; Grünewald, S; Gustafson, R; Günther, M; Hage, B; Hammer, D; Hanna, C; Hanson, J; Harms, J; Harry, G; Harstad, E; Hayler, T; Heefner, J; Heng, I S; Heptonstall, A; Heurs, M; Hewitson, M; Hild, S; Hirose, E; Hoak, D; Hosken, D; Hough, J; Hoyland, D; Huttner, S H; Ingram, D; Innerhofer, E; Ito, M; Itoh, Y; Ivanov, A; Johnson, B; Johnson, W W; Jones, D I; Jones, G; Jones, R; Ju, L; Kalmus, Peter Ignaz Paul; Kalogera, V; Kasprzyk, D; Katsavounidis, E; Kawabe, K; Kawamura, S; Kawazoe, F; Kells, W; Keppel, D G; Khalili, F Ya; Kim, C; King, P; Kissel, J S; Klimenko, S; Kokeyama, K; Kondrashov, V; Kopparapu, R K; Kozak, D; Krishnan, B; Krämer, M; Kwee, P; Lam, P K; Landry, M; Lantz, B; Lazzarini, A; Lei, M; Leiner, J; Leonhardt, V; Leonor, I; Libbrecht, K; Lindquist, P; Lockerbie, N A; Longo, M; Lormand, M; Lubinski, M; Luck, H; Lyne, A G; MacInnis, M; Machenschalk, B; Mageswaran, M; Mailand, K; Malec, M; Mandic, V; Marano, S; Marka, S; Markowitz, J; Maros, E; Martin, I; Marx, J N; Mason, K; Matone, L; Matta, V; Mavalvala, N; McCarthy, R; McClelland, D E; McGuire, S C; McHugh, M; McKenzie, K; McWilliams, S; Meier, T; Melissinos, A C; Mendell, G; Mercer, R A; Meshkov, S; Messaritaki, E; Messenger, C J; Meyers, D; Mikhailov, E; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Miyakawa, O; Mohanty, S; Moreno, G; Mossavi, K; Mow Lowry, C; Moylan, A; Mukherjee, S; Muller-Ebhardt, H; Munch, J; Murray, P; Myers, E; Myers, J; Müller, G; Newton, G; Nishizawa, A; Numata, K; O'Reilly, B; O'Shaughnessy, R; Ottaway, D J; Overmier, H; Owen, B J; Pan, Y; Papa, M A; Parameshwaraiah, V; Patel, P; Pedraza, M; Penn, S; Pierro, V; Pinto, I M; Pitkin, M; Pletsch, H; Plissi, M V; Postiglione, F; Prix, R; Quetschke, V; Raab, F; Rabeling, D; Radkins, H; Rahkola, R; Rainer, N; Rakhmanov, M; Ray-Majumder, S; Re, V; Rehbein, H; Reid, S; Reitze, D H; Ribichini, L; Riesen, R; Riles, K; Rivera, B; Robertson, N A; Robinson, C; Robinson, E L; Roddy, S; Rodríguez, A; Rogan, A M; Rollins, J; Romano, J D; Romie, J; Route, R; Rowan, S; Ruet, L; Russell, P; Ryan, K; Rüdiger, A; Sakata, S; Samidi, M; Sancho de la Jordana, L; Sandberg, V; Sannibale, V; Saraf, S; Sarin, P; Sathyaprakash, B S; Sato, S; Saulson, P R; Savage, R; Savov, P; Schediwy, S; Schilling, R; Schnabel, R; Schofield, R; Schutz, B F; Schwinberg, P; Scott, S M; Searle, A C; Sears, B; Seifert, F; Sellers, D; Sengupta, A S; Shawhan, P; Shoemaker, D H; Sibley, A; Sidles, J A; Siemens, X; Sigg, D; Sinha, S; Sintes, A M; Slagmolen, B; Slutsky, J; Smith, J R; Smith, M R; Somiya, K; Strain, K A; Strom, D M; Stuver, A; Summerscales, T Z; Sun, K X; Sung, M; Sutton, P J; Takahashi, H; Tanner, D B; Taylor, R; Thacker, J; Thorne, K A; Thorne, K S; Thüring, A; Tokmakov, K V; Torres, C; Torrie, C; Traylor, G; Trias, M; Tyler, W; Ugolini, D W; Urbanek, K; Vahlbruch, H; Vallisneri, M; Van Den Broeck, C; Varvella, M; Vass, S; Vecchio, A; Veitch, J; Veitch, P; Villar, A; Vorvick, C; Vyachanin, S P; Waldman, S J; Wallace, L; Ward, H; Ward, R; Watts, K; Weidner, A; Weinert, M; Weinstein, A; Weiss, R; Wen, S; Wette, K; Whelan, J T; Whitcomb, S E; Whiting, B F; Wilkinson, C; Willems, P A; Williams, L; Willke, B; Wilmut, I; Winkler, W; Wipf, C C; Wise, S; Wiseman, A G; Woan, G; Woods, D; Wooley, R; Worden, J; Wu, W; Yakushin, I; Yamamoto, H; Yan, Z; Yoshida, S; Yunes, N; Zanolin, M; Zhang, J; Zhang, L; Zhao, C; Zotov, N; Zucker, M; Zweizig, J; zur Muhlen, H

    2007-01-01

    We present upper limits on the gravitational wave emission from 78 radio pulsars based on data from the third and fourth science runs of the LIGO and GEO600 gravitational wave detectors. The data from both runs have been combined coherently to maximise sensitivity. For the first time pulsars within binary (or multiple) systems have been included in the search by taking into account the signal modulation due to their orbits. Our upper limits are therefore the first measured for 56 of these pulsars. For the remaining 22, our results improve on previous upper limits by up to a factor of 10. For example, our tightest upper limit on the gravitational strain is 3.2e-25 for PSRJ1603-7202, and the equatorial ellipticity of PSRJ2124-3358 is less than 10e-6. Furthermore, our strain upper limit for the Crab pulsar is only three times greater than the fiducial spin-down limit.

  3. Could aerosol emissions be used for regional heat wave mitigation?

    Directory of Open Access Journals (Sweden)

    D. N. Bernstein

    2013-07-01

    Full Text Available Geoengineering applications by injection of sulfate aerosols into the stratosphere are under consideration as a measure of last resort to counter global warming. Here a potential regional-scale application to offset the impacts of heat waves is critically examined. Using the Weather Research and Forecasting model with fully coupled chemistry (WRF-Chem, the effect of regional-scale sulfate aerosol emission over California in each of two days of the July 2006 heat wave is used to quantify potential reductions in surface temperature as a function of emission rates in a layer at 12 km altitude. Local meteorological factors yield geographical differences in surface air temperature sensitivity. For emission rates of approximately 30 μg m−2 s−1 of sulfate aerosols (with standard WRF-Chem size distribution over the region, temperature decreases of around 7 °C result during the middle part of the day over the Central Valley, one of the areas hardest hit by the heat wave. Regions more ventilated with oceanic air such as Los Angeles have slightly smaller reductions. The length of the hottest part of the day is also reduced. Advection effects on the aerosol cloud must be more carefully forecast for smaller injection regions. Verification of the impacts could be done via measurements of differences in reflected and surface downward shortwave. Such regional geoengineering applications with specific near-term target effects but smaller cost and side effects could potentially provide a means of testing larger scale applications. However, design considerations for regional applications, such as a preference for injection at a level of relatively low wind speed, differ from those for global applications. The size of the required injections and the necessity of injection close to the target region raise substantial concerns. The evaluation of this regional-scale application is thus consistent with global model evaluations, emphasizing that mitigation via

  4. Observation of dispersive wave emission by temporal cavity solitons.

    Science.gov (United States)

    Jang, Jae K; Erkintalo, Miro; Murdoch, Stuart G; Coen, Stéphane

    2014-10-01

    We examine a coherently-driven, dispersion-managed, passive Kerr fiber ring resonator and report, to the best of our knowledge, the first direct experimental observation of dispersive wave emission by temporal cavity solitons (CSs). Our observations are in excellent agreement with analytical predictions and they are fully corroborated by numerical simulations. These results lead to a better understanding of the behavior of temporal CSs under conditions where higher-order dispersion plays a significant role. Significantly, since temporal CSs manifest themselves in monolithic microresonators, our results are likely to explain the origins of spectral features observed in broadband Kerr frequency combs. PMID:25360913

  5. Exhaust Gas Emissions from a Rotating Detonation-wave Engine

    Science.gov (United States)

    Kailasanath, Kazhikathra; Schwer, Douglas

    2015-11-01

    Rotating detonation-wave engines (RDE) are a form of continuous detonation-wave engines. They potentially provide further gains in performance than an intermittent or pulsed detonation-wave engine (PDE). The overall flow field in an idealized RDE, primarily consisting of two concentric cylinders, has been discussed in previous meetings. Because of the high pressures involved and the lack of adequate reaction mechanisms for this regime, previous simulations have typically used simplified chemistry models. However, understanding the exhaust species concentrations in propulsion devices is important for both performance considerations as well as estimating pollutant emissions. Progress towards addressing this need will be discussed in this talk. In this approach, an induction parameter model is used for simulating the detonation but a more detailed finite-chemistry model including NOx chemistry is used in the expansion flow region, where the pressures are lower and the uncertainties in the chemistry model are greatly reduced. Results show that overall radical concentrations in the exhaust flow are substantially lower than from earlier predictions with simplified models. The performance of a baseline hydrogen/air RDE increased from 4940 s to 5000 s with the expansion flow chemistry, due to recombination of radicals and more production of H2O, resulting in additional heat release. Work sponsored by the Office of Naval Research.

  6. Generating functions for q-Bernstein, q-Meyer-Konig-Zeller and q-Beta basis

    OpenAIRE

    Gupta, Vijay; Kim, Taekyun; Choi, Jongsung; Kim, Young-Hee

    2010-01-01

    The present paper deals with the q-analogue of Bernstein, Meyer-Konig-Zeller and Beta operators. Here we estimate the generating functions for q-Bernstein, q-Meyer-Konig-Zeller and q-Beta basis functions.

  7. Proofs of the Cantor-Bernstein theorem a mathematical excursion

    CERN Document Server

    Hinkis, Arie

    2013-01-01

    This book offers an excursion through the developmental area of research mathematics. It presents some 40 papers, published between the 1870s and the 1970s, on proofs of the Cantor-Bernstein theorem and the related Bernstein division theorem. While the emphasis is placed on providing accurate proofs, similar to the originals, the discussion is broadened to include aspects that pertain to the methodology of the development of mathematics and to the philosophy of mathematics. Works of prominent mathematicians and logicians are reviewed, including Cantor, Dedekind, Schröder, Bernstein, Borel, Zermelo, Poincaré, Russell, Peano, the Königs, Hausdorff, Sierpinski, Tarski, Banach, Brouwer and several others mainly of the Polish and the Dutch schools. In its attempt to present a diachronic narrative of one mathematical topic, the book resembles Lakatos’ celebrated book Proofs and Refutations. Indeed, some of the observations made by Lakatos are corroborated herein. The analogy between the two books is clearly an...

  8. Gravity Wave Emission by Spontaneous Imbalance of Baroclinic Waves in the Continuously Stratified Rotating Annulus

    Science.gov (United States)

    Borchert, Sebastian; Achatz, Ulrich; Rieper, Felix; Fruman, Mark

    2013-04-01

    We use a numerical model of the classic differentially heated rotating annulus experiment to study the spontaneous emission of gravity waves (GWs) from jet stream imbalances, which is a major source of these waves in the atmosphere for which no satisfactory parameterization exists. Atmospheric observations are the main tool for the testing and verification of theoretical concepts but have their limitations. Given their specific potential for yielding reproducible data and for studying process dependence on external system parameters, laboratory experiments are an invaluable complementary tool. Experiments with a rotating annulus exhibiting a jet modulated by large-scale waves due to baroclinic instability have already been used to study GWs: Williams et al (2008) observed spontaneously emitted interfacial GWs in a two-layer flow, and Jacoby et al (2011) detected GWs emitted from boundary-layer instabilities in a differentially heated rotating annulus. Employing a finite-volume code for the numerical simulation of a continuously stratified liquid in a differentially heated rotating annulus, we here investigate the GWs in a wide and shallow annulus with relatively large temperature difference between inner and outer cylinder walls. In this atmosphere-like regime where the Brunt-Vaisala frequency is larger than the inertial frequency, various analyses suggest a distinct gravity wave activity. To identify regions of GW emission we decompose the flow into the geostrophic and ageostrophic part through the inversion of the quasi-geostrophic potential vorticity (e.g. Verkley, 2009). The analysis of the geostrophic sources of the ageostrophic flow indicates that, in addition to boundary layer instabilities, spontaneous imbalance in the jet region acts as an important source mechanism. Jacoby, T. N. L., Read, P. L., Williams, P. D. and Young, R. M. B., 2011: Generation of inertia-gravity waves in the rotating thermal annulus by a localised boundary layer instability. Geophys

  9. 77 FR 75200 - AllianceBernstein Active ETFs, Inc., et al.; Notice of Application

    Science.gov (United States)

    2012-12-19

    ... COMMISSION AllianceBernstein Active ETFs, Inc., et al.; Notice of Application December 13, 2012. AGENCY...Bernstein Active ETFs, Inc. (``Corporation''), AllianceBernstein L.P. (``Adviser''), and ALPS Distributors... Business Day's NAV and the market closing price or mid-point of the bid/ask spread at the time...

  10. Recent EBW Emission Results and Plans for a 350 kW 28 GHz EC/EBW Heating System on NSTX

    Czech Academy of Sciences Publication Activity Database

    Taylor, G.; Diem, S.J.; Ellis, R.A.; Fredd, E.; Greenough, N.I.; Hosea, J.C.; Bigelow, T.S.; Caughman, J.B.; Rasmussen, D.A.; Ryan, P.; Wilgen, J.B.; Harvey, R.W.; Smirnov, A.P.; Ershov, N.M.; Preinhaelter, Josef; Urban, Jakub; Ram, A.K.

    2007-01-01

    Roč. 52, č. 16 (2007), s. 304-304. ISSN 0003-0503. [Annual Meeting of the Division of Plasma Physics/49th./. Orlando, Florida, 12.11.2007-16.11.2007] Institutional research plan: CEZ:AV0Z20430508 Keywords : Conversion * Emission * Tokamaks * Electron Bernstein waves * Simulation * NSTX Subject RIV: BL - Plasma and Gas Discharge Physics http://meetings.aps.org/Meeting/DPP07/Content/901

  11. Wave propagation, scattering and emission in complex media

    Science.gov (United States)

    Jin, Ya-Qiu

    . Gitterman. Transformation of the spectrum of scattered radiation in randomly inhomogeneous absorptive plasma layer / G. V. Jandieri, G. D. Aburjunia, V. G. Jandieri. Numerical analysis of microwave heating on saponification reaction / K. Huang, K. Jia -- IV. Scattering from complex targets. Analysis of electromagnetic scattering from layered crossed-gratings of circular cylinders using lattice sums technique / K. Yasumoto, H. T. Jia. Scattering by a body in a random medium / M. Tateiba, Z. Q. Meng, H. El-Ocla. A rigorous analysis of electromagnetic scattering from multilayered crossed-arrays of metallic cylinders / H. T. Jia, K. Yasumoto. Vector models of non-stable and spatially-distributed radar objects / A. Surkov ... [et al.]. Simulation of algorithm of orthogonal signals forming and processing used to estimate back scattering matrix of non-stable radar objects / D. Nosov ... [et al.]. New features of scattering from a dielectric film on a reflecting metal substrate / Z. H. Gu, I. M. Fuks, M. Ciftan. A higher order FDTD method for EM wave propagation in collision plasmas / S. B. Liu, J. J. Mo, N. C. Yuan -- V. Radiative transfer and remote sensing. Simulating microwave emission from Antarctica ice sheet with a coherent model / M. Tedesco, P. Pampaloni. Scattering and emission from inhomogeneous vegetation canopy and alien target by using three-dimensional Vector Radiative Transfer (3D-VRT) equation / Y. Q. Jin, Z. C. Liang. Analysis of land types using high-resolution satellite images and fractal approach / H. G. Zhang ... [et al.]. Data fusion of RADARSAT SAR and DMSP SSM/I for monitoring sea ice of China's Bohai Sea / Y. Q. Jin. Retrieving atmospheric temperature profiles from simulated microwave radiometer data with artificial neural networks / Z. G. Yao, H. B. Chen -- VI. Wave propagation and wireless communication. Wireless propagation in urban environments: modeling and experimental verification / D. Erricolo ... [et al.]. An overview of physics-based wave

  12. Photoacoustic shock wave emission and cavitation from structured optical fiber tips

    International Nuclear Information System (INIS)

    Photoacoustic waves generated at the tip of an optical fiber consist of a compressive shock wave followed by tensile diffraction waves. These tensile waves overlap along the fiber axis and form a cloud of cavitation bubbles. We demonstrate that shaping the fiber tip through micromachining alters the number and direction of the emitted waves and cavitation clouds. Shock wave emission and cavitation patterns from five distinctively shaped fiber tips have been studied experimentally and compared to a linear wave propagation model. In particular, multiple shock wave emission and generation of strong tension away from the fiber axis have been realized using modified fiber tips. These altered waveforms may be applied for novel microsurgery protocols, such as fiber-based histotripsy, by utilizing bubble-shock wave interaction

  13. Photoacoustic shock wave emission and cavitation from structured optical fiber tips

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadzadeh, M.; Gonzalez-Avila, S. R.; Ohl, C. D., E-mail: cdohl@ntu.edu.sg [School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore); Wan, Y. C.; Wang, X.; Zheng, H. [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore)

    2016-01-11

    Photoacoustic waves generated at the tip of an optical fiber consist of a compressive shock wave followed by tensile diffraction waves. These tensile waves overlap along the fiber axis and form a cloud of cavitation bubbles. We demonstrate that shaping the fiber tip through micromachining alters the number and direction of the emitted waves and cavitation clouds. Shock wave emission and cavitation patterns from five distinctively shaped fiber tips have been studied experimentally and compared to a linear wave propagation model. In particular, multiple shock wave emission and generation of strong tension away from the fiber axis have been realized using modified fiber tips. These altered waveforms may be applied for novel microsurgery protocols, such as fiber-based histotripsy, by utilizing bubble-shock wave interaction.

  14. Nonlinear Wave Interactions as Emission Process of Type II Radio Bursts

    OpenAIRE

    Ganse, Urs; Kilian, Patrick; Spanier, Felix; Vainio, Rami

    2012-01-01

    The emission of fundamental and harmonic frequency radio waves of type II radio bursts are assumed to be products of three-wave interaction processes of beam-excited Langmuir waves. Using a particle-in-cell code, we have performed simulations of the assumed emission region, a CME foreshock with two counterstreaming electron beams. Analysis of wavemodes within the simulation shows self-consistent excitation of beam driven modes, which yield interaction products at both fundamental and harmonic...

  15. Pointwise Approximation for the Iterated Boolean Sums of Bernstein Operators

    Institute of Scientific and Technical Information of China (English)

    HUO Xiao-yan; LI Cui-xiang; YAO Qiu-mei

    2013-01-01

    In this paper,with the help of modulus of smoothness ω2r(4)(f,t),we discuss the pointwise approximation properties for the iterated Boolean sums of Bernstein operator Bnn and obtain direct and inverse theorems when 1-1/r ≤ λ ≤ 1,r ∈ N.

  16. On -Euler Numbers Related to the Modified -Bernstein Polynomials

    OpenAIRE

    Min-Soo Kim; Daeyeoul Kim; Taekyun Kim

    2010-01-01

    We consider q-Euler numbers, polynomials, and q-Stirling numbers of first and second kinds. Finally, we investigate some interesting properties of the modified q-Bernstein polynomials related to q-Euler numbers and q-Stirling numbers by using fermionic p-adic integrals on ℤp.

  17. A field-emission based vacuum device for the generation of THz waves

    Science.gov (United States)

    Lin, Ming-Chieh

    2005-03-01

    Terahertz waves have been used to characterize the electronic, vibrational and compositional properties of solid, liquid and gas phase materials during the past decade. More and more applications in imaging science and technology call for the well development of THz wave sources. Amplification and generation of a high frequency electromagnetic wave are a common interest of field emission based devices. In the present work, we propose a vacuum electronic device based on field emission mechanism for the generation of THz waves. To verify our thinking and designs, the cold tests and the hot tests have been studied via the simulation tools, SUPERFISH and MAGIC. In the hot tests, two types of electron emission mechanisms are considered. One is the field emission and the other is the explosive emission. The preliminary design of the device is carried out and tested by the numerical simulations. The simulation results show that an electronic efficiency up to 4% can be achieved without employing any magnetic circuits.

  18. Electron Cyclotron Wave Experiments at the WEGA Stellarator

    Czech Academy of Sciences Publication Activity Database

    Laqua, H.P.; Andruczyk, D.; Holzhauer, E.; Marsen, S.; Otte, M.; Podoba, Y.Y.; Preinhaelter, Josef; Urban, Jakub; Warr, G.B.

    Warsaw : European Physical Society, 2007 - (Gąsior, P.; Wołowski, J.), s. 4-7 ISBN 978-83-926290-0-9. - (Europhysics Conference Abstracts). [European Physical Society Conference on Plasma Physics/34th./. Warsaw (PL), 02.07.2007-06.07.2007] Institutional research plan: CEZ:AV0Z20430508 Keywords : Conversion * Emission * Stellarators * Electron Bernstein waves * Simulation Subject RIV: BL - Plasma and Gas Discharge Physics http://www.eps2007.ifpilm.waw.pl/pdf/P1_154.pdf

  19. ULF Waves at Mercury

    Science.gov (United States)

    Kim, E.-H.; Boardsen, S. A.; Johnson, J. R.; Slavin, J. A.

    2016-02-01

    This chapter provides a brief overview of the observed characteristics of ultra-low-frequency (ULF) waves at Mercury. It shows how field-aligned propagating ULF waves at Mercury can be generated by externally driven fast compressional waves (FWs) via mode conversion at the ion-ion hybrid resonance. Then, the chapter reviews the interpretation that the strong magnetic compressional waves near and its harmonics observed with 20 of Mercury's magnetic equator could be the ion Bernstein wave (IBW) mode. A recent statistical study of ULF waves at Mercury based on MESSENGER data reported the occurrence and polarization of the detected waves. The chapter further introduces the field line resonance and the electromagnetic ion Bernstein waves to explain such waves, and shows that both theories can partially explain the observations.

  20. Colliding neutron stars --- Gravitational waves, neutrino emission, and gamma-ray bursts

    OpenAIRE

    Ruffert, Maximilian; Janka, H. -Thomas

    1998-01-01

    Three-dimensional hydrodynamical simulations are presented for the direct head-on or off-center collision of two neutron stars, employing a basically Newtonian PPM code but including the emission of gravitational waves and their back-reaction on the hydrodynamical flow. A physical nuclear equation of state is used that allows us to follow the thermodynamical evolution of the stellar matter and to compute the emission of neutrinos. Predicted gravitational wave signals, luminosities and wavefor...

  1. Numerical study for electromagnetic wave emission from intrinsic Josephson junction stacks with a dielectric cover

    Science.gov (United States)

    Koyama, T.; Matsumoto, H.; Ota, Y.; Machida, M.

    2013-08-01

    Electromagnetic (EM) wave emission from the intrinsic Josephson junction stacks (IJJ’s) covered with a thin dielectric medium is numerically investigated, using the multi-scale simulation method developed in our previous paper. It is shown that the power of emitted EM waves is considerably increased in the IJJ’s with a dielectric cover. The emission from the n = 2 resonance mode is greatly enhanced. The enhancement is caused by the excitation of a solitonic mode.

  2. The nonlinear Bernstein-Schr\\"odinger equation in Economics

    OpenAIRE

    Galichon, Alfred; Kominers, Scott; WEBER, Simon

    2015-01-01

    In this paper we relate the Equilibrium Assignment Problem (EAP), which is underlying in several economics models, to a system of nonlinear equations that we call the "nonlinear Bernstein-Schr\\"odinger system", which is well-known in the linear case, but whose nonlinear extension does not seem to have been studied. We apply this connection to derive an existence result for the EAP, and an efficient computational method.

  3. The nonlinear Bernstein-Schr\\"odinger equation in Economics

    OpenAIRE

    Alfred Galichon; Scott Kominers; Simon Weber

    2015-01-01

    In this paper we relate the Equilibrium Assignment Problem (EAP), which is underlying in several economics models, to a system of nonlinear equations that we call the "nonlinear Bernstein-Schr\\"odinger system", which is well-known in the linear case, but whose nonlinear extension does not seem to have been studied. We apply this connection to derive an existence result for the EAP, and an efficient computational method.

  4. Semiparametric Bernstein-von Mises for the error standard deviation

    OpenAIRE

    Jonge, de, B.; Zanten, van, M.

    2013-01-01

    We study Bayes procedures for nonparametric regression problems with Gaussian errors, giving conditions under which a Bernstein-von Mises result holds for the marginal posterior distribution of the error standard deviation. We apply our general results to show that a single Bayes procedure using a hierarchical spline-based prior on the regression function and an independent prior on the error variance, can simultaneously achieve adaptive, rate-optimal estimation of a smooth, multivariate regr...

  5. Solutions of differential equations in a Bernstein polynomial basis

    Science.gov (United States)

    Idrees Bhatti, M.; Bracken, P.

    2007-08-01

    An algorithm for approximating solutions to differential equations in a modified new Bernstein polynomial basis is introduced. The algorithm expands the desired solution in terms of a set of continuous polynomials over a closed interval and then makes use of the Galerkin method to determine the expansion coefficients to construct a solution. Matrix formulation is used throughout the entire procedure. However, accuracy and efficiency are dependent on the size of the set of Bernstein polynomials and the procedure is much simpler compared to the piecewise B spline method for solving differential equations. A recursive definition of the Bernstein polynomials and their derivatives are also presented. The current procedure is implemented to solve three linear equations and one nonlinear equation, and excellent agreement is found between the exact and approximate solutions. In addition, the algorithm improves the accuracy and efficiency of the traditional methods for solving differential equations that rely on much more complicated numerical techniques. This procedure has great potential to be implemented in more complex systems where there are no exact solutions available except approximations.

  6. Emission of dispersive waves from a train of dark solitons in optical fibers

    CERN Document Server

    Marest, T; Conforti, M; Mussot, A; Milian, C; Skryabin, D V; Kudlinski, A

    2016-01-01

    We report the experimental observation of multiple dispersive waves emitted in the anomalous dispersion region of an optical fiber from a train of dark solitons. Each individual dispersive wave can be associated to one particular dark soliton of the train, using phase-matching arguments involving higher-order dispersion and soliton velocity. For a large number of dark solitons (>10), we observe the formation of a continuum associated with the efficient emission of dispersive waves.

  7. Emission of dispersive waves from a train of dark solitons in optical fibers

    Science.gov (United States)

    Marest, T.; Mas Arabí, C.; Conforti, M.; Mussot, A.; Milián, C.; Skryabin, D. V.; Kudlinski, A.

    2016-06-01

    We report the experimental observation of multiple dispersive waves emitted in the anomalous dispersion region of an optical fiber from a train of dark solitons. Each individual dispersive wave can be associated to one particular dark soliton of the train, using phase-matching arguments involving higher-order dispersion and soliton velocity. For a large number of dark solitons (>10), we observe the formation of a continuum associated with the efficient emission of dispersive waves.

  8. Potential Sources of Gravitational Wave Emission and Laser Beam Interferometers

    OpenAIRE

    Pacheco, J. A. de Freitas

    2000-01-01

    The properties of potential gravitational wave sources like neutron stars, black holes and binary systems are reviewed, as well as the different contributions (stochastic and continuous) to the gravitational wave background. The detectability of these sources by the present generation of laser beam interferometers, which will be fully operational around 2002, is also considered.

  9. Identification of broad-band waves above the auroral acceleration region: Cluster observations

    Directory of Open Access Journals (Sweden)

    M. Backrud

    2004-12-01

    Full Text Available We investigate broad-band emissions at frequencies above the ion gyrofrequency on auroral field lines at geocentric distances of about 4.5 Earth radii. Observations by the Cluster satellites are used to study the wave characteristics and to determine the wave modes involved. All events include some bursts of broad-band emissions with a substantial component of the electric field parallel to the geomagnetic field. Studying the polarization of the emissions we find that linear waves in a homogeneous plasma can be used to theoretically describe the observations.

    The broad-band emissions include short bursts of ion acoustic waves, and longer periods of ion Bernstein and Electrostatic Ion Cyclotron (EIC waves. All waves occur during the same event within a few seconds, with EIC waves as the most common. Theoretically, there is no sharp limit between these wave modes and they can be described by the same dispersion surface. These emissions are closely associated with low-frequency Alfvén waves, indicating a possible generation mechanism.

    Key words. Magnetospheric physics (auroral phenomena; electric fields; plasma waves and instabilities

  10. Unprecedentedly Strong and Narrow Electromagnetic Emissions Stimulated by High-Frequency Radio Waves in the Ionosphere

    International Nuclear Information System (INIS)

    Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA

  11. Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere.

    Science.gov (United States)

    Norin, L; Leyser, T B; Nordblad, E; Thidé, B; McCarrick, M

    2009-02-13

    Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA. PMID:19257596

  12. VLF wave emissions by pulsed and dc electron beams in space. I - Spacelab 2 observations

    Science.gov (United States)

    Reeves, G. D.; Banks, P. M.; Neubert, T.; Bush, R. I.; Williamson, P. R.

    1988-01-01

    The properties of radio waves generated by electron beams in space were investigated using data from the wideband wave receiver on the Spacelab 2. The VLF observations were found to confirm the results of the STS 3/OSS-1 mission. It was found that a 1-keV electron beam injected from the orbiter produced copious broadband electromagnetic emissions. When the electron beam was square-wave modulated, narrow-band emissions at the pulsing frequency and harmonics of that frequency were produced along with the broadband emissions. The observations indicated that dc 50-mA electron beams and pulsed 50-percent duty-cycle 100-mA beams produce broadband radiation which is comparable in intensity and spectral shape at all points for which the wave field was sampled.

  13. Spontaneous emission of a photon: wave packet structures and atom-photon entanglement

    OpenAIRE

    Fedorov, M. V.; Efremov, M. A.; Kazakov, A. E.; Chan, K W; Law, C. K.; Eberly, J. H.

    2004-01-01

    Spontaneous emission of a photon by an atom is described theoretically in three dimensions with the initial wave function of a finite-mass atom taken in the form of a finite-size wave packet. Recoil and wave-packet spreading are taken into account. The total atom-photon wave function is found in the momentum and coordinate representations as the solution of an initial-value problem. The atom-photon entanglement arising in such a process is shown to be closely related to the structure of atom ...

  14. Formation of black hole and emission of gravitational waves

    OpenAIRE

    Nakamura,Takashi

    2006-01-01

    Numerical simulations were performed for the formation process of rotating black holes. It is suggested that Kerr black holes are formed for wide ranges of initial parameters. The nature of gravitational waves from a test particle falling into a Kerr black hole as well as the development of 3D numerical relativity for the coalescing binary neutron stars are discussed.

  15. Formation of black hole and emission of gravitational waves.

    Science.gov (United States)

    Nakamura, Takashi

    2006-12-01

    Numerical simulations were performed for the formation process of rotating black holes. It is suggested that Kerr black holes are formed for wide ranges of initial parameters. The nature of gravitational waves from a test particle falling into a Kerr black hole as well as the development of 3D numerical relativity for the coalescing binary neutron stars are discussed. PMID:25792793

  16. Equatorial noise emissions with quasiperiodic modulation of wave intensity

    Czech Academy of Sciences Publication Activity Database

    Němec, F.; Santolík, Ondřej; Hrbáčková, Zuzana; Pickett, J. S.; Cornilleau-Wehrlin, N.

    2015-01-01

    Roč. 120, č. 4 (2015), s. 2649-2661. ISSN 2169-9380 R&D Projects: GA MŠk(CZ) LH11122 Institutional support: RVO:68378289 Keywords : equatorial noise * magnetosonic waves * quasiperiodic modulation Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.440, year: 2013 http://onlinelibrary.wiley.com/doi/10.1002/2014JA020816/full

  17. Bernstein - Von Mises theorem and its application in survival analysis

    Czech Academy of Sciences Publication Activity Database

    Timková, Jana

    2010-01-01

    Roč. 22, č. 3 (2010), s. 115-122. ISSN 1210-8022. [16. letní škola JČMF Robust 2010. Králíky, 30.01.2010-05.02.2010] R&D Projects: GA AV ČR(CZ) IAA101120604 Institutional research plan: CEZ:AV0Z10750506 Keywords : Cox model * bayesian asymptotics * survival function Subject RIV: BB - Applied Statistics, Operational Research http://library.utia.cas.cz/separaty/2010/SI/timkova-bernstein - von mises theorem and its application in survival analysis.pdf

  18. Gravitation-Wave Emission in Shift-Symmetric Horndeski Theories.

    Science.gov (United States)

    Barausse, Enrico; Yagi, Kent

    2015-11-20

    Gravity theories beyond general relativity typically predict dipolar gravitational emission by compact-star binaries. This emission is sourced by "sensitivity" parameters depending on the stellar compactness. We introduce a general formalism to calculate these parameters, and show that in shift-symmetric Horndeski theories stellar sensitivities and dipolar radiation vanish, provided that the binary's dynamics is perturbative (i.e., the post-Newtonian formalism is applicable) and cosmological-expansion effects can be neglected. This allows one to reproduce the binary-pulsar-observed orbital decay. PMID:26636840

  19. Dynamics and gravitational-wave emission of neutron-star merger remnants

    CERN Document Server

    Bauswein, A; Stergioulas, N; Janka, H -T

    2016-01-01

    The coalescence of a neutron-star binary is likely to result in the formation of a neutron-star merger remnant for a large range of binary mass configurations. The massive merger remnant shows strong oscillations, which are excited by the merging process, and emits gravitational waves. Here we discuss possibilities and prospects of inferring unknown stellar properties of neutron stars by the detection of postmerger gravitational-wave emission, which thus leads to constraints of the equation of state of high-density matter. In particular, the dominant oscillation frequency of the postmerger remnant provides tight limits to neutron-star radii. We mention first steps towards a practical implementation of future gravitational-wave searches for the postmerger emission. Moreover, we outline possibilities to estimate the unknown maximum mass of nonrotating neutron stars from such types of measurements. Finally, we review the origin and scientific implications of secondary peaks in the gravitational-wave spectrum of ...

  20. Bernstein, Dukheim e a sociologia da educação na Inglaterra Bernstein, Durkheim, and the Britsh sociology of education

    OpenAIRE

    Brian Davies

    2003-01-01

    Neste texto o autor procura elucidar o modo pelo qual Basil Bernstein utilizou e enriqueceu a contribuição de Durkheim para a análise de questões abordadas pela sociologia da educação.The author attempts to elucidate how Basil Bernstein used and enhanced Durkheim's contribution to the analysis of issues addressed by the sociology of education.

  1. Gravitational wave emission and spin-down of young pulsars

    International Nuclear Information System (INIS)

    The rotation frequencies of young pulsars are systematically below their theoretical Kepler limit. r-modes have been suggested as a possible explanation for this observation. With the help of semi-analytic expressions that make it possible to assess the uncertainties of the r-mode scenario due to the impact of uncertainties in underlying microphysics, we perform a quantitative analysis of the spin-down and the emitted gravitational waves of young pulsars. We find that the frequency to which r-modes spin-down a young neutron star (NS) is surprisingly insensitive to both the microscopic details and the saturation amplitude. Comparing our result to astrophysical data, we show that for a range of sufficiently large saturation amplitudes r-modes provide a viable spin-down scenario and that all observed young pulsars are very likely already outside the r-mode instability region. Therefore, the most promising sources for gravitational wave detection are unobserved NSs associated with recent supernovae, and we find that advanced LIGO should be able to see several of them. Our analysis shows that despite the coupling of the spin-down and thermal evolution, a power-law spin-down with an effective braking index n rm ≤ 7 is realized. Because of this, the gravitational wave strain amplitude is completely independent of both the r-mode saturation amplitude and the microphysics and depends on the saturation mechanism only within some tens of percent. However, the gravitational wave frequency depends on the amplitude, and we provide the required expected timing parameter ranges to look for promising sources in future searches.

  2. Gravitational wave emission and spin-down of young pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Alford, Mark G.; Schwenzer, Kai [Department of Physics, Washington University, St. Louis, MO 63130 (United States)

    2014-01-20

    The rotation frequencies of young pulsars are systematically below their theoretical Kepler limit. r-modes have been suggested as a possible explanation for this observation. With the help of semi-analytic expressions that make it possible to assess the uncertainties of the r-mode scenario due to the impact of uncertainties in underlying microphysics, we perform a quantitative analysis of the spin-down and the emitted gravitational waves of young pulsars. We find that the frequency to which r-modes spin-down a young neutron star (NS) is surprisingly insensitive to both the microscopic details and the saturation amplitude. Comparing our result to astrophysical data, we show that for a range of sufficiently large saturation amplitudes r-modes provide a viable spin-down scenario and that all observed young pulsars are very likely already outside the r-mode instability region. Therefore, the most promising sources for gravitational wave detection are unobserved NSs associated with recent supernovae, and we find that advanced LIGO should be able to see several of them. Our analysis shows that despite the coupling of the spin-down and thermal evolution, a power-law spin-down with an effective braking index n {sub rm} ≤ 7 is realized. Because of this, the gravitational wave strain amplitude is completely independent of both the r-mode saturation amplitude and the microphysics and depends on the saturation mechanism only within some tens of percent. However, the gravitational wave frequency depends on the amplitude, and we provide the required expected timing parameter ranges to look for promising sources in future searches.

  3. Stimulated emission of fast Alfv\\'en waves within magnetically confined fusion plasmas

    CERN Document Server

    Cook, J W S; Chapman, S C

    2016-01-01

    A fast Alfv\\'en wave with finite amplitude is shown to grow by a stimulated emission process that we propose for exploitation in toroidal magnetically confined fusion plasmas. Stimulated emission occurs while the wave propagates inward through the outer mid-plane plasma, where a population inversion of the energy distribution of fusion-born ions is observed to arise naturally. Fully nonlinear first principles simulations, which self-consistently evolve particles and fields under the Maxwell-Lorentz system, demonstrate this novel "alpha-particle channelling" scenario for the first time.

  4. Observationally constraining gravitational wave emission from short gamma-ray burst remnants

    Science.gov (United States)

    Lasky, Paul D.; Glampedakis, Kostas

    2016-05-01

    Observations of short gamma-ray bursts indicate ongoing energy injection following the prompt emission, with the most likely candidate being the birth of a rapidly rotating, highly magnetized neutron star. We utilize X-ray observations of the burst remnant to constrain properties of the nascent neutron star, including its magnetic field-induced ellipticity and the saturation amplitude of various oscillation modes. Moreover, we derive strict upper limits on the gravitational wave emission from these objects by looking only at the X-ray light curve, showing the burst remnants are unlikely to be detected in the near future using ground-based gravitational wave interferometers, such as Advanced LIGO.

  5. In-phase electrodynamics and terahertz wave emission in extended intrinsic Josephson junctions

    Science.gov (United States)

    Koyama, Tomio; Matsumoto, Hideki; Machida, Masahiko; Kadowaki, Kazuo

    2009-03-01

    Strong emission of subterahertz electromagnetic (EM) waves has been observed recently in the high Tc superconductor Bi2Sr2CaCu2O8 intrinsic Josephson junctions (IJJ’s). We investigate numerically the dynamics of the EM fields both inside and outside the IJJ’s emitting terahertz EM waves under a constant bias current, using two-dimensional models composed of IJJ’s and the space surrounding them: (1) xy model and (2) xz model. In the xy model we investigate the EM modes excited in the rectangular junctions. In the voltage state the Josephson oscillation generates the oscillating EM field having nodes inside the junctions. The number of nodes depends on the DC voltage appearing in the junctions, and their direction is parallel to the shorter side of the junctions. The EM field shows a complex distribution pattern in the near field region. In the region far from the junctions we have only the expanding EM wave oscillating with the Josephson frequency. In the xz model we study the EM waves emitted in the xz plane from the junctions covered with normal electrodes. It is shown that the power of the emitted EM waves has distribution similar to that in the dipole emission in the system where electrodes of the same size are attached on top and bottom junctions. In the asymmetric system where the lower electrode is larger than the upper one the power distribution of emitted EM wave deviates from that in the dipole emission.

  6. Numerical study for electromagnetic wave emission from intrinsic Josephson junction stacks with a dielectric cover

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, T., E-mail: tkoyama@imr.tohoku.ac.jp [IMR, Tohoku University, Sendai 980-8577 (Japan); Matsumoto, H. [Department of Physics, Tohoku University, Sendai 980-8577 (Japan); Ota, Y. [ASI, Riken, Wako-shi 351-0198 (Japan); Machida, M. [CCSE, Japan Atomic Energy Agency, Kashiwa 277-8587 (Japan)

    2013-08-15

    Highlights: ► Simulation of the THz emission from IJJ’s with a dielectric cover is performed. ► The emission power is increased by the dielectric cover. ► The n = 2 cavity mode is anomalously enhanced. -- Abstract: Electromagnetic (EM) wave emission from the intrinsic Josephson junction stacks (IJJ’s) covered with a thin dielectric medium is numerically investigated, using the multi-scale simulation method developed in our previous paper. It is shown that the power of emitted EM waves is considerably increased in the IJJ’s with a dielectric cover. The emission from the n = 2 resonance mode is greatly enhanced. The enhancement is caused by the excitation of a solitonic mode.

  7. Intense plasma wave emissions associated with Saturn's moon Rhea

    Czech Academy of Sciences Publication Activity Database

    Santolík, Ondřej; Gurnett, D. A.; Jones, G. H.; Schippers, P.; Crary, F. J.; Leisner, J. S.; Hospodarsky, G. B.; Kurth, W. S.; Russell, C. T.; Dougherty, M. K.

    2011-01-01

    Roč. 38, - (2011), L19204/1-L19204/7. ISSN 0094-8276 R&D Projects: GA ČR GAP205/10/2279; GA MŠk(CZ) ME10001; GA MŠk(CZ) LH11122 Institutional research plan: CEZ:AV0Z30420517 Keywords : III RADIO -BURSTS * LANGMUIR-WAVES * ICY MOON * CASSINI * ELECTRONS Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.792, year: 2011 http://www.agu.org/pubs/crossref/2011/2011GL049219.shtml

  8. On the absence of plasma wave emissions and the magnetic field orientation in the distant magnetosheath

    Science.gov (United States)

    Coroniti, F. V.; Greenstadt, E. W.; Moses, S. L.; Tsurutani, B. T.; Smith, E. J.

    1994-01-01

    In early September, 1983 ISEE-3 made a long traversal of the distant dawnside magnetosheath starting near x = -150 R(sub E) downstream. The distant magnetosheath often contains moderately intense plasma wave emissions at frequencies from several hundred Hz to 5 kHz. However, over time scales of many days, a clear correlation exists between the occurrence of the plasma waves and the cone angle (theta(sub xB)) between the magnetic field and the plasma flow velocity (x-direction). For theta(sub xB) large (small), the plasma wave amplitudes are near background (high). Sudden (less than 1 minute) changes in the local magnetic field orientation produce correspondingly sudden changes in the wave amplitudes. Statistically, the wave amplitudes decrease continuously with increasing theta(sub xB).

  9. Influence of short gravity waves on thermal radio emission of water surface

    Science.gov (United States)

    Ilin, V. A.; Naumov, A. A.; Rayzer, V. Y.; Filonovich, S. R.; Etkin, V. S.

    1985-06-01

    An experimental study is presented of the thermal radio emission caused by short waves, accompanied by a quantitative interpretation of the data obtained. Emphasis is on an analysis of the variation in radio brightness contrast as a function of steepness of the short gravity waves, measured by means of a high-frequency radiometer operating in the lambda = 0.8 cm range. Waves were artificially generated in a small channel, wavelength 8 to 40 cm, height 0.6 to 3 cm. Due to the high sensitivity of the radiometric apparatus used, effects were recorded which were related to the influence of the profile and steepness of the short gravity waves. The possibility of using the geometrical optics approximation for quantitative interpretation of the experimental data is demonstrated. The model is based on essentially non-Gaussian statistics of slopes corresponding to quasimonochromatic waves of finite amplitude.

  10. Gravitational Waves versus X and Gamma Ray Emission in a Short Gamma-Ray Burst

    OpenAIRE

    Oliveira, F. G.; Rueda, Jorge A.; Ruffini, Remo

    2012-01-01

    The recent progress in the understanding the physical nature of neutron star equilibrium configurations and the first observational evidence of a genuinely short gamma-ray burst, GRB 090227B, allows to give an estimate of the gravitational waves versus the X and Gamma-ray emission in a short gamma-ray burst.

  11. Detection and localization of defects in complex structures by Nonlinear Elastic Wave Spectroscopy and Acoustic Emission

    Czech Academy of Sciences Publication Activity Database

    Převorovský, Zdeněk; Chlada, Milan; Krofta, Josef; Kober, Jan; Dos Santos, S.

    Le Mans: The University of Maine in Le Mans, 2013 - (Bentahar, M.; Kenderian, S.; Green, R.). s. 95 [Internanational Symposium on Nondestructive Characterization of Materials /13./. 20.05.2013-24.05.2013, Le Mans] Institutional support: RVO:61388998 Keywords : nonlinear elastic wave spectroscopy * acoustic emission * nondestructive testing * damage initiation * civil structure Subject RIV: JS - Reliability ; Quality Management, Testing

  12. Effect of heat waves on VOC emissions from vegetation and urban air quality

    Science.gov (United States)

    Churkina, G.; Kuik, F.; Lauer, A.; Bonn, B.; Butler, T. M.

    2015-12-01

    Programs to plant millions of trees in cities around the world aim at the reduction of summer temperatures, increase carbon storage, storm water control, provision of space for recreation, as well as poverty alleviation. Although these multiple benefits speak positively for urban greening programs, the programs do not take into account how close human and natural systems are coupled in urban areas. Elevated temperatures together with anthropogenic emissions of air and water pollutants distinguish the urban system. Urban and sub-urban vegetation responds to ambient changes and reacts with pollutants. Neglecting this coupling may lead to unforeseen drawbacks of urban greening programs. The potential for emissions of volatile organic compounds (VOC) from vegetation combined with anthropogenic emissions to produce ozone has long been recognized. This potential increases under rising temperatures. Here we investigate how heat waves affect emissions of VOC from urban vegetation and corresponding ground-level ozone. In this study we use Weather Research and Forecasting Model with coupled atmospheric chemistry (WRF-CHEM) to quantify these feedbacks in Berlin, Germany during the 2006 heat wave. VOC emissions from vegetation are simulated with MEGAN 2.0 coupled with WRF-CHEM. Our preliminary results indicate that contribution of VOCs from vegetation to ozone formation may increase by more than twofold during the heat wave period. We highlight the importance of the vegetation for urban areas under changing climate and discuss associated tradeoffs.

  13. Glass Melt Emissivity, Viscosity, and Foaming Monitoring with Millimeter-Waves

    International Nuclear Information System (INIS)

    Nuclear waste glass processing efficiencies, improved melter control to anomalies such as foaming, and environmental compliance would be facilitated by the availability of on-line monitoring technologies. It has been shown that the millimeter-wave (MMW) range of the electromagnetic spectrum (0.3-10 mm) is ideally suited to hot melter environments by having wavelengths long enough to penetrate optically obscure views yet short enough to provide spatial resolution with reliable refractory quasi-optical components. A thermal return reflection (TRR) method has been developed that allows a millimeter-wave pyrometer to determine emissivity by returning a portion of the thermal emission as a probe. Melt glass viscosities in the range 20 -2000 Poise and specific gravities have been measured by rates of flow and displacements inside hollow MMW ceramic waveguides immersed into the melts. Glass foaming has been observed by detecting the melt surface swelling followed by the increase in surface emissivity after gases break the surface

  14. Kinematics of ICMEs/shocks: blast wave reconstruction using type II emissions

    CERN Document Server

    Corona-Romero, P; Aguilar-Rodriguez, E; de-la-Luz, V; Mejia-Ambriz, J C

    2015-01-01

    We present a physical methodology to reconstruct the trajectory of interplanetary shocks using type II radio emission data. This technique calculates the shock trajectory assuming that the disturbance propagates as a blast wave in the interplanetary medium. We applied this Blast Wave Reconstruction (BWR) technique to analyze eight fast Earth-directed ICMEs/shocks associated with type II emissions. The technique deduces a shock trajectory that reproduces the type II frequency drifts, and calculates shock onset speed, shock transit time and shock speed at 1~AU. There were good agreements comparing the BWR results with the type II spectra, with data from coronagraph images, {\\it in situ} measurements, and interplanetary scintillation (IPS) observations. Perturbations on the type II data affect the accuracy of the BWR technique. This methodology could be applied to track interplanetary shocks causing TII emissions in real-time, to predict the shock arrival time and shock speed at 1~AU.

  15. Kinematics of ICMEs/Shocks: Blast Wave Reconstruction Using Type-II Emissions

    Science.gov (United States)

    Corona-Romero, P.; Gonzalez-Esparza, J. A.; Aguilar-Rodriguez, E.; De-la-Luz, V.; Mejia-Ambriz, J. C.

    2015-09-01

    We present a physical methodology for reconstructing the trajectory of interplanetary shocks using Type-II radio emission data. This technique calculates the shock trajectory assuming that the disturbance propagates as a blast wave in the interplanetary medium. We applied this blast-wave reconstruction (BWR) technique to analyze eight fast Earth-directed ICMEs/shocks associated with Type-II emissions. The technique deduces a shock trajectory that reproduces the Type-II frequency drifts and calculates shock onset speed, shock travel time, and shock speed at 1 AU. The BWR results agreed well with the Type-II spectra, with data from coronagraph images, in-situ measurements, and interplanetary scintillation observations. Perturbations in the Type-II data affect the accuracy of the BWR technique. This methodology could be applied to track interplanetary shocks causing Type-II emissions in real-time and to predict the shock arrival time and shock speed at 1 AU.

  16. First results from EBW emission diagnostics on COMPASS

    Energy Technology Data Exchange (ETDEWEB)

    Zajac, J.; Preinhaelter, J.; Aftanas, M.; Bilkova, P.; Boehm, P.; Fuchs, V.; Weinzettl, V.; Zacek, F. [Institute of Plasma Physics AS CR, v.v.i., Association EURATOM/IPP.CR, Prague (Czech Republic); Urban, J. [Institute of Plasma Physics AS CR, v.v.i., Association EURATOM/IPP.CR, Prague (Czech Republic); CEA, IRFM, F-13108 Saint Paul-lez-Durance (France); Nanobashvili, S. [Andronikashvili Institute of Physics, Tamarashvili St. 6, 0177 Tbilisi (Georgia)

    2012-10-15

    COMPASS tokamak shots at low magnetic field feature overdense plasmas during the extended current flat-top phase. The first harmonic of the electron cyclotron emission is completely cutoff for O and X modes and so the emission caused by electron Bernstein waves (EBWs) propagating obliquely with respect to the magnetic field and undergoing so called EBW-X-O conversion process can be observed. We perform an angular scan of the EBW emission during a set of comparable shots in order to determine the optimum antenna direction. A weak dependence of the radiative temperature on the antenna angles indicates an influence of multiple reflections from the vessel wall. The low temperature at the mode conversion region is responsible for the collisional damping of EBW, which can explain several times lower measured radiative temperature than the electron temperature measured by the Thomson scattering system.

  17. $L^p$ Bernstein Inequalities and Inverse Theorems for RBF Approximation on $\\mathbb{R}^d$

    CERN Document Server

    Ward, John Paul

    2010-01-01

    Bernstein inequalities and inverse theorems are a recent development in the theory of radial basis function(RBF) approximation. The purpose of this paper is to extend what is known by deriving $L^p$ Bernstein inequalities for RBF networks on $\\mathbb{R}^d$. These inequalities involve bounding a Bessel-potential norm of an RBF network by its corresponding $L^p$ norm in terms of the separation radius associated with the network. The Bernstein inequalities will then be used to prove the corresponding inverse theorems.

  18. A teoria de Basil Bernstein: alguns aspectos fundamentais

    Directory of Open Access Journals (Sweden)

    Ana Maria Morais

    2007-12-01

    Full Text Available The article begins with a reference to the pieces of work that Basil Bernstein considered to have been the landmarks of the evolution of his thought. This is followed by a detailed description of the two models that contain the main concepts of his theory – Model of Cultural Reproduction and Transformation and Model of Pedagogic Discourse – where the theoretical meaning of these models and concepts is explained and where are given some examples of how to put them into practice at the level of pedagogic texts and contexts. The article also includes the most recent developments of Bernstein’s thought by explaining his ideas about the forms discourses can take – Vertical and Horizontal Discourses. Finally, Bernstein’s theory is approached within the framework of the empirical research, highlighting his epistemological positioning and explicating the methodological model that he suggested should be the driving force of any theory.

  19. Effect of secondary electron emission on the propagation of dust acoustic waves in a dusty plasma

    International Nuclear Information System (INIS)

    The effect of secondary electron emission on dust acoustic wave (DA) propagation has been investigated based on orbit motion limited theory of dust grain charging. The emitted secondaries are assumed to have the same temperature as that of the ambient plasma electrons so that the plasma effectively consists of three components: the ions, electrons, and the variable charge dusts. Together with the effect of secondary emission, the effect of ion and electron capture and ionization of neutral atoms and recombination have been included in the ion and electron fluid equations. Small amplitude perturbation is considered about a charge neutral steady state. It is seen that if the dust charge is positive there may occur under certain conditions zero frequency exponentially growing perturbation about the equilibrium. The possibility of the occurrence of such purely growing mode in a dusty plasma was not noted earlier. The frequency and damping decrement of DA waves in dusty plasmas with negatively charged dust and also of DA waves with positively charged dust, when they exist, are determined. Comparisons with corresponding results of DA waves in the absence of secondary emission are exhibited graphically

  20. Interpretation of Cluster data on chorus emissions using the backward wave oscillator model

    International Nuclear Information System (INIS)

    The measurements of chorus emissions by four closely separated Cluster spacecraft provide important information concerning the chorus generation mechanism. They confirm such properties of the wave source as their strong localization near the equatorial cross section of a magnetic flux tube, an almost parallel average wave-vector direction with respect to the geomagnetic field, and an energy flux direction pointing outward from the generation region. Inside this region, Cluster discovered strong temporal and spatial variations in the amplitude with correlation scale lengths of the order of 100 km across the magnetic flux. The wave electric field reached 30 mV/m, and the maximum growth and damping rates are of the order of a few hundreds of s-1. These and other properties of the detected chorus emissions are discussed here in relation with the backward wave oscillator mechanism. According to this mechanism, a succession of whistler wave packets is generated in a small near-equatorial region with temporal and spatial characteristics close to the Cluster data. Amplitudes and frequency spectra, as well as dynamical features of the Poynting flux of chorus are estimated and compared with the Cluster measurements

  1. Evidence for four- and three-wave interactions in solar type III radio emissions

    Directory of Open Access Journals (Sweden)

    G. Thejappa

    2013-08-01

    of the oppositely propagating up- and down-shifted daughter Langmuir waves excited by the OTSI probably is the emission mechanism of the second harmonic radiation, and (3 the Langmuir collapse follows the route of OTSI in some of the type III radio bursts.

  2. Numerical study for electromagnetic wave emission in thin samples of intrinsic Josephson junctions

    Science.gov (United States)

    Koyama, T.; Matsumoto, H.; Ohta, Y.; Machida, M.

    2011-11-01

    Emission of THz electromagnetic waves from thin samples of intrinsic Josephson junctions (IJJ’s) is numerically studied, using the xz-model. We show that the spatial symmetry of the electromagnetic excitations corresponding to the π-cavity mode is different from that of the 2 π-cavity mode in the IJJ’s where the junction parameters such as the Josephson critical current are weakly inhomogeneous. In such IJJ’s the emission in the [0 0 1] direction, which is forbidden in the dipole emission, appears at the π-cavity mode resonance, whereas it is not observed in the 2 π-cavity mode resonance. It is also shown that the strong emission occurs when the transition between branches in the I- V characteristics takes place.

  3. Plastic damping of Alfv\\'en waves in magnetar flares and delayed afterglow emission

    CERN Document Server

    Li, Xinyu

    2015-01-01

    Magnetar flares generate Alfv\\'en waves bouncing in the closed magnetosphere with energy up to $\\sim 10^{46}$ erg. We show that on a 10-ms timescale the waves are transmitted into the star and form a compressed packet of high energy density. This packet strongly shears the stellar crust and initiates a plastic flow, heating the crust and melting it hundreds of meters below the surface. A fraction of the deposited plastic heat is eventually conducted to the stellar surface, contributing to the surface afterglow months to years after the flare. A large fraction of heat is lost to neutrino emission or conducted into the core of the neutron star.

  4. q-Bernstein polynomials, q-Stirling numbers and q-Bernoulli polynomials

    OpenAIRE

    Kim, T.

    2010-01-01

    In this paper, we give new identities involving Phillips q-Bernstein polynomials and we derive some interesting properties of q-Berstein polynomials associated with q-Stirling numbers and q-Bernoulli polynomials.

  5. On the Fermionic -adic Integral Representation of Bernstein Polynomials Associated with Euler Numbers and Polynomials

    Directory of Open Access Journals (Sweden)

    Ryoo CS

    2010-01-01

    Full Text Available The purpose of this paper is to give some properties of several Bernstein type polynomials to represent the fermionic -adic integral on . From these properties, we derive some interesting identities on the Euler numbers and polynomials.

  6. Bernstein dual-Petrov-Galerkin method: application to 2D time fractional diffusion equation

    CERN Document Server

    Jani, Mostafa; Babolian, Esmail

    2016-01-01

    In this paper, we develop a dual-Petrov-Galerkin method using Bernstein polynomials. The method is then implemented for the numerical simulation of the two-dimensional subdiffusion equation. The method is based on a finite difference discretization in time and a spectral method in space utilizing a suitable compact combinations of dual Bernstein basis as the test functions and the Bernstein polynomials as the trial ones. We derive the exact sparse operational matrix of differentiation for the dual Bernstein basis which provides a matrix-based approach for spatial discretization of the problem. It is also shown that the proposed method leads to banded linear systems. Finally some numerical examples are provided to show the efficiency and accuracy of the method.

  7. On the approximation properties of bivariate $(p, q)-$Bernstein operators

    OpenAIRE

    Karaisa, Ali

    2016-01-01

    In the present study, we have given a corrigendum to our paper on the approximation properties of bivariate $(p, q)-$Bernstein operators. Recently, we \\cite{kar} have defined the bivariate $(p, q)-$Bernstein operators. Later, we have aware of Acar et. al \\cite{acar} already have given some moments. In this case, we have revised \\cite[Lemma 2.3]{kar}.

  8. Solution of the Lane-Emden Equation Using the Bernstein Operational Matrix of Integration

    OpenAIRE

    Narayan Kumar; Pandey, Rajesh K.; Carlo Cattani

    2011-01-01

    Lane-Emden's equation has fundamental importance in the recent analysis of many problems in relativity and astrophysics including some models of density profiles for dark matter halos. An efficient numerical method is presented for linear and nonlinear Lane-Emden-type equations using the Bernstein polynomial operational matrix of integration. The proposed approach is different from other numerical techniques as it is based on the Bernstein polynomial integration matrix. Some illustrative exam...

  9. Emission of terahertz electromagnetic waves by vortex flow in high- Tc superconductors

    Science.gov (United States)

    Tachiki, Masashi; Iizuka, Mikio; Minami, Kazuo; Tejima, Shogo; Nakamura, Hisashi

    2006-05-01

    Continuous terahertz electromagnetic waves have new applications in scientific and industrial fields such as medicine and information technology. Cuprate high-temperature superconductors have a layer structure, and form a naturally multi-connected Josephson junction system called intrinsic Josephson junction (IJJ). In IJJ, there appears a new excitation called the Josephson plasma. Its frequency is in the region of terahertz inside the superconducting energy gap. The excited plasma wave is converted into an electromagnetic wave at sample surfaces. Therefore the IJJ has a great potential to generate terahertz continuous wave. Here we report the results of simulations to find the optimum condition for obtaining the strongest emission power of the terahertz waves. The simulations were carried out using our theory. Since the simulation uses very large-sized coupled nonlinear equations therefore difficult to compute, we used the fastest supercomputer named as Earth Simulator. We found that the quite intense continuous terahertz coherent wave is emitted from a small sample with high-energy efficiency.

  10. Gravitational wave hotspots: Ranking potential locations of single-source gravitational wave emission

    International Nuclear Information System (INIS)

    The steadily improving sensitivity of pulsar timing arrays (PTAs) suggests that gravitational waves (GWs) from supermassive black hole binary (SMBHB) systems in the nearby universe will be detectable sometime during the next decade. Currently, PTAs assume an equal probability of detection from every sky position, but as evidence grows for a non-isotropic distribution of sources, is there a most likely sky position for a detectable single source of GWs? In this paper, a collection of Galactic catalogs is used to calculate various metrics related to the detectability of a single GW source resolvable above a GW background, assuming that every galaxy has the same probability of containing an SMBHB. Our analyses of these data reveal small probabilities that one of these sources is currently in the PTA band, but as sensitivity is improved regions of consistent probability density are found in predictable locations, specifically around local galaxy clusters.

  11. Emission of dispersive waves from a train of dark solitons in optical fibers.

    Science.gov (United States)

    Marest, T; Mas Arabí, C; Conforti, M; Mussot, A; Milián, C; Skryabin, D V; Kudlinski, A

    2016-06-01

    We report the experimental observation of multiple dispersive waves (DWs) emitted in the anomalous dispersion region of an optical fiber from a train of dark solitons. Each DW can be associated to one dark soliton of the train, using phase-matching arguments involving higher-order dispersion and soliton velocity. For a large number of dark solitons (>10), we observe the formation of a continuum associated with the efficient emission of DWs. PMID:27244387

  12. Solid waves and acoustic emission first phase: Problems direct and inverse and equations elasto dynamics fields

    International Nuclear Information System (INIS)

    The present work is the first of a series of three memoirs briefs, destinadas to revise the classic theoretical foundations that allow to understand the generation,la diffusion and the detection of the elastic waves in those been accustomed to from the point of view of the mechanics of the means continuos. The study is faced in the mark of the non destructive rehearsals, emphasizing aspects related with the rehearsals based on the acoustic emission of the material defects

  13. THz wave emission from argon in two-color laser field

    Institute of Scientific and Technical Information of China (English)

    杜玲玲; 赵松峰; 周效信; 赵增秀

    2015-01-01

    Terahertz (THz) wave emission from argon atom in a two-color laser pulses is studied numerically by solving the one-dimensional (1D) time-dependent Schr ¨odinger equation. The THz spectra we obtained include both discontinuous and continuum ones. By using the special basis functions that we previously proposed, our analysis points out that the discontinuous and continuum parts are contributed by bound–bound and continuum–continuum transition of atomic energy levels. Although the atomic wave function is strongly dressed during the interaction with laser fields, our identification for the discontinuous part of the THz wave shows that the transition between highly excited bound states can still be well described by the field-free basis function in the tunneling ionization regime.

  14. Probing the environment of gravitational wave transient sources with TeV afterglow emission

    CERN Document Server

    Zhu, Qin-Yu

    2016-01-01

    Recently, Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO) detected gravitational wave (GW) transients from mergers of binary black holes (BHs). The system may also produce a wide-angle, relativistic outflow if the claimed short GRB detected by GBM is in real association with GW 150914. It was suggested that mergers of double neutron stars (or neutron star-black hole binaries), another promising source of GW transients, also produce fast, wide-angle outflows. In this paper, we calculate the high-energy gamma-ray emission arising from the blast waves driven by these wide-angle outflows. We find that TeV emission arising from the inverse-Compton process in the relativistic outflow resulted from mergers of binary BHs similar to those in GW 150914 could be detectable by ground-based IACT telescopes such as Cherenkov Telescope Array (CTA) if the sources occur in { a dense medium with density $n > 0.3 cm^{-3}$}. For neutron star-neutron star (NS-NS) and NS-BH mergers, TeV emission from the wide-...

  15. Identification of natural plasma emissions observed close to the plasmapause by the Cluster-Whisper relaxation sounder

    Directory of Open Access Journals (Sweden)

    P. Canu

    Full Text Available We use the data collected by the Whisper instrument onboard the Cluster spacecraft for a first test of its capabilities in the identification of the natural plasma waves observed in the Earth’s magnetosphere. The main signatures observed at the plasma frequency, upper hybrid frequency, and electron Bernstein modes were often difficult to be reliably recognized on previous missions. We use here the characteristic frequencies provided by the resonances triggered by the relaxation sounder of Whisper to identify with good confidence the various signatures detected in the complex wave spectra collected close to the plasmapause. Coupled with the good sensitivity, frequency and time resolution of Whisper, the resonances detected by the sounder allow one to precisely spot these natural emissions. This first analysis seems to confirm the interpretation of Geos observations: the natural emissions observed in Bernstein modes above the plasma frequency, now widely observed onboard Cluster, are not modeled by a single Maxwellian electrons distribution function. Therefore, multi-temperature electron distribution functions should be considered.

    Key words. Space plasma physics (active perturbation experiments; waves and instabilities; instrument and techniques

  16. THz wave emission of GaAs induced by He+ ion implantation

    Science.gov (United States)

    Yang, Kang; Cao, Jianqing; Huang, Can; Ji, Te; Zhang, Zengyan; Liu, Qi; Wu, Shengwei; Lin, Jun; Zhao, Hongwei; Zhu, Zhiyong

    2013-07-01

    Semi-Insulating Gallium Arsenide (SI-GaAs) was implanted with 1.5 MeV He+ ions and THz photoconductive antenna (PCA) was prepared on the implanted SI-GaAs surface. The antenna was applied as the THz wave emission source of a terahertz time domain spectroscopy (THz-TDS) and the THz wave emission ability was studied as a function of the implantation dose. It is found that the THz signal intensity increases with increase of implantation dose, and after reaching to a peak value the THz signal intensity decreases with further implantation. The best THz emission ability was achieved at a dose value between 1 × 1015 and 1 × 1016 ions/cm2. It is believed that the implantation induced defects in the 1 μm-thick surface area are responsible for the enhanced THz emission ability. The work proved that better THz photoconductive antenna than that made by low-temperature-grown GaAs (LT-GaAs) can be produced through He-ion implantation at proper dose.

  17. THz wave emission of GaAs induced by He{sup +} ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Kang [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai (China); Graduate University of Chinese Academy of Sciences, Beijing (China); Cao, Jianqing [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai (China); Huang, Can [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai (China); Graduate University of Chinese Academy of Sciences, Beijing (China); Ji, Te; Zhang, Zengyan; Liu, Qi; Wu, Shengwei; Lin, Jun; Zhao, Hongwei [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai (China); Zhu, Zhiyong, E-mail: zhuzhiyong@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai (China)

    2013-07-15

    Semi-Insulating Gallium Arsenide (SI-GaAs) was implanted with 1.5 MeV He{sup +} ions and THz photoconductive antenna (PCA) was prepared on the implanted SI-GaAs surface. The antenna was applied as the THz wave emission source of a terahertz time domain spectroscopy (THz-TDS) and the THz wave emission ability was studied as a function of the implantation dose. It is found that the THz signal intensity increases with increase of implantation dose, and after reaching to a peak value the THz signal intensity decreases with further implantation. The best THz emission ability was achieved at a dose value between 1 × 10{sup 15} and 1 × 10{sup 16} ions/cm{sup 2}. It is believed that the implantation induced defects in the 1 μm-thick surface area are responsible for the enhanced THz emission ability. The work proved that better THz photoconductive antenna than that made by low-temperature-grown GaAs (LT-GaAs) can be produced through He-ion implantation at proper dose.

  18. THz wave emission of GaAs induced by He+ ion implantation

    International Nuclear Information System (INIS)

    Semi-Insulating Gallium Arsenide (SI-GaAs) was implanted with 1.5 MeV He+ ions and THz photoconductive antenna (PCA) was prepared on the implanted SI-GaAs surface. The antenna was applied as the THz wave emission source of a terahertz time domain spectroscopy (THz-TDS) and the THz wave emission ability was studied as a function of the implantation dose. It is found that the THz signal intensity increases with increase of implantation dose, and after reaching to a peak value the THz signal intensity decreases with further implantation. The best THz emission ability was achieved at a dose value between 1 × 1015 and 1 × 1016 ions/cm2. It is believed that the implantation induced defects in the 1 μm-thick surface area are responsible for the enhanced THz emission ability. The work proved that better THz photoconductive antenna than that made by low-temperature-grown GaAs (LT-GaAs) can be produced through He-ion implantation at proper dose

  19. Emission, absorption, and tunneling of whistler waves in an inhomogeneous magnetic field

    International Nuclear Information System (INIS)

    Measurements of electron cyclotron emission parallel to a magnetic field in the regime where finite density effects are important and measurements of electron cyclotron wave tunneling parallel to a magnetic field are reported. The experiments were conducted in a low-temperature (T/sub e/ approx.2 eV) moderate-density (n/sub e/ = 3 x 109--3 x 1012 cm-3) gas discharge plasma in a magnetic mirror geometry. Experimental results are compared with two models, both of which employ Kirchoff's law to relate emission and absorption. In one model, absorption from hot-plasma theory is calculated and in the other a cold-plasma Budden tunneling type analysis is employed. Both models are in reasonable agreement, with the data generally bracketing the experimental results, and the experiment could not resolve which model is superior. The utility of whistler mode cyclotron emission as an electron temperature diagnostic measurement on mirror machines is confirmed

  20. Radio-wave emission due to hypervelocity impacts and its correlation with optical observations

    Science.gov (United States)

    Takano, T.; Maki, K.; Yamori, A.

    This paper describes the most interesting phenomena of radio-wave emission due to hypervelocity impacts. A projectile of polycarbonate with 1.1 g weight was accelerated by a rail gun to 3.8 km/sec, and hit two targets which are a 2 mm thick aluminum plate upstream and a 45 mm diameter aluminum column downstream, respectively. The projectile first breaks wires to give a triggering signal to a data recorder, then penetrates the aluminum plate, and finally hit the column, The emitted radio-waves propagate through the chamber window, and are received by antennas at each frequency band. The receivers in 22 GHz- and 2 GHz-bands consist of a low noise amplifier, a mixer, a local oscillator and an IF amplifier , respectively. The receiver in 1 MHz-band is a simple RF amplifier. The outputs of all receivers are fed to a data recorder which is actually a high-speed digital oscilloscope with a large amount of memory. The radio-waves were successfully recorded in 22 GHz-band with 500 MHz bandwidth, in 2 GHz-band with 300 MHz bandwidth, and in 1MHz-band. The waveforms in 22 GHz- and 2 GHz-bands coincide well each other, and are composed of two groups of sharp impulses with a separation of about 20 micro seconds. The width of an impulse is less than 2 n sec. which is the resolution limit of the data recorder. We carried out optical observations using an ultra-high speed camera simultaneously through another window of the chamber. The time interval between scenes is 2 micro sec. We can see a faint light of the projectile before the first impact to the plate, and then a brilliant gas exploding backward from the plate and forward to the column. After hitting the column target, the brilliant gas flows to the chamber wall and is reflected back to make a mixture with dark gas in the chamber. Excellent correlation between radio-wave emission and the observed optical phenomena was obtained in the experiment. It is easily conceived that the radio-waves consist of quite a wide frequency

  1. Particle-In-Cell, self-consistent electromagnetic wave emission simulations of type III radio bursts

    CERN Document Server

    Tsiklauri, David

    2010-01-01

    High-resolution, 1.5D Particle-in-Cell, relativistic, fully electromagnetic simulations are used to model electromagnetic wave emission generation in the context of solar type III radio bursts. The model studies generation of electromagnetic waves by a super-thermal, hot beam of electrons injected into a plasma thread that contains uniform longitudinal magnetic field and a parabolic density gradient. In effect, a single magnetic line connecting Sun to earth is considered, for which four cases are studied. (i) We find that the physical system without a beam is stable and only low amplitude level electromagnetic drift waves (noise) are excited. (ii) The beam injection direction is controlled by setting either longitudinal or oblique electron initial drift speed, i.e. by setting the beam pitch angle. In the case of zero pitch angle, the beam excites only electrostatic, standing waves, oscillating at local plasma frequency, in the beam injection spatial location, and only low level electromagnetic drift wave nois...

  2. Brain blood flow studies with single photon emission computed tomography in patients with plateau waves

    International Nuclear Information System (INIS)

    The authors studied brain blood flow with single photon emission computed tomography (SPECT) in two patients with plateau waves. The intracranial pressure and blood pressure were also monitored continuously in these patients. They included one patient with brain-tumor (rt. sphenoid ridge meningioma) and another with hydrocephalus after subarachnoid hemorrhage due to rupture of lt. internal carotid aneurysm. The intracranial pressure was monitored through an indwelling ventricular catheter attached to a pressure transducer. The blood pressure was recorded through an intraarterial catheter placed in the dorsalis pedis artery. Brain blood flow was studied with Headtome SET-011 (manufactured by Shimazu Co., Ltd.). For this flow measurement study, an intravenous injection of Xenon-133 of about 30 mCi was given via an antecubital vein. The position of the slice for the SPECT was selected so as to obtain information not only from the cerebral hemisphere but also from the brain stem : a cross section 25 deg over the orbito-meatal line, passing through the inferior aspect of the frontal horn, the basal ganglia, the lower recessus of the third ventricle and the brain stem. The results indicated that, in the cerebral hemisphere, plateau waves were accompanied by a decrease in blood flow, whereas, in the brain stem, the blood flow showed little change during plateau waves as compared with the interval phase between two plateau waves. These observations may explain why there is no rise in the blood pressure and why patients are often alert during plateau waves. (author)

  3. MALDI-TOF Baseline Drift Removal Using Stochastic Bernstein Approximation

    Directory of Open Access Journals (Sweden)

    Howard Daniel

    2006-01-01

    Full Text Available Stochastic Bernstein (SB approximation can tackle the problem of baseline drift correction of instrumentation data. This is demonstrated for spectral data: matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF data. Two SB schemes for removing the baseline drift are presented: iterative and direct. Following an explanation of the origin of the MALDI-TOF baseline drift that sheds light on the inherent difficulty of its removal by chemical means, SB baseline drift removal is illustrated for both proteomics and genomics MALDI-TOF data sets. SB is an elegant signal processing method to obtain a numerically straightforward baseline shift removal method as it includes a free parameter that can be optimized for different baseline drift removal applications. Therefore, research that determines putative biomarkers from the spectral data might benefit from a sensitivity analysis to the underlying spectral measurement that is made possible by varying the SB free parameter. This can be manually tuned (for constant or tuned with evolutionary computation (for .

  4. Study of tokamak plasma electron cyclotron emission during electron-wave interaction near the lower hybrid frequency

    International Nuclear Information System (INIS)

    The quasilinear theory of wave-particle interaction is presented. Diagnostic possibilities of electron cyclotron emission. To study the cyclotron radiation (whose wavelength is millimeter order), a Michelson type interferometer is used, which allows to select willingly the useful spectral field. The cyclotron radiation allows characterization of a pumping wave: in studying the spectrum part where plasma is optically thin the studied cyclotron emissivity is directly proportional to absorbed power by plasma. Saturation of power absorption by plasma has been observed and studied

  5. Bernstein-Kantorovich算子的迭代布尔和的逼近性质%APPROXIMATION QUALITIES FOR THE ITERATED BOOLEAN SUMS OF BERNSTEIN-KANTOROVICH OPERATORS

    Institute of Scientific and Technical Information of China (English)

    李翠香; 任孟霞

    2007-01-01

    本文利用光滑模及最佳逼近多项式的性质,研究了Bernstein-Kantorovich算子的迭代布尔和对Lp[0,1]中的函数的逼近性质,得到了逼近正定理,弱逆不等式及等价定理.

  6. Investigation of wave emission phenomena in dual frequency capacitive discharges using particle-in-cell simulation

    International Nuclear Information System (INIS)

    Dual frequency capacitively coupled discharges are widely used during fabrication of modern-day integrated circuits, because of low cost and robust uniformity over broad areas. At low pressure, stochastic or collisionless electron heating is important in such discharges. The stochastic heating occurs adjacent to the sheath edge due to energy transfer from the oscillating high voltage electron sheath to electrons. The present research discusses evidence of wave emission from the sheath in such discharges, with a frequency near the electron plasma frequency. These waves are damped very promptly as they propagate away from the sheath towards the bulk plasma, by Landau damping or some related mechanism. In this work, the occurrence of strong wave phenomena during the expanding and collapsing phase of the low frequency sheath has been investigated. This is the result of a progressive breakdown of quasi-neutrality close to the electron sheath edge. The characteristics of waves in the dual-frequency case are entirely different from the single-frequency case studied in earlier works. The existence of a field reversal phenomenon, occurring several times within a lower frequency period in the proximity of the sheath is also reported. Electron trapping near to the field reversal regions also occurs many times during a lower frequency period. The emission of waves is associated with these field reversal regions. It is observed that the field reversal and electron trapping effects appear under conditions typical of many recent experiments, and are consequently of much greater practical interest than similar effects in single frequency discharges, which occur only under extreme conditions that are not usually realized in experiments. (paper)

  7. Stress wave emission and cavitation bubble dynamics by nanosecond optical breakdown in a tissue phantom

    Science.gov (United States)

    Brujan, Emil-Alexandru; Vogel, Alfred

    2006-07-01

    Stress wave emission and cavitation bubble dynamics after optical breakdown in water and a tissue phantom with Nd: YAG laser pulses of 6 ns duration were investigated both experimentally and numerically to obtain a better understanding of the physical mechanisms involved in plasma-mediated laser surgery. Experimental tools were high-speed photography with 50000 frames s(-1) , and acoustic measurements. The tissue phantom consisted of a transparent polyacrylamide (PAA) gel, the elastic properties of which can be controlled by modifying the water content. Breakdown in water produced a purely compressive stress wave. By contrast, in stiff PAA samples and for sufficiently large pulse energies, the compression wave was followed by an intense tensile wave, similar to the behaviour previously observed in cornea. The elastic/plastic response of the medium led to a significant decrease of the maximum size of the cavitation bubble and to a shortening of its oscillation period which was found to be related to the generation of the tensile stress wave upon breakdown. For increasing elastic modulus of the PAA, both the amplitudes of the bubble oscillation and of the stress wave emitted during bubble collapse decreased until the bubble oscillation was so strongly damped that no collapse stress wave was emitted. Numerical simulations were performed using a spherical model of bubble dynamics which includes the compressibility and elastic/plastic behaviour of the medium, viscosity, density and surface tension. The calculations revealed that consideration of the elastic/plastic behaviour of the medium surrounding the bubble is essential to describe the experimentally observed bipolar shape of the stress wave emitted upon optical breakdown. Water is a poor tissue model because the shape of the emitted stress waves and the bubble dynamics differ strongly for both materials. The mechanical properties of PAA were also found to be quite different from those of tissues. Experimental and

  8. INTEGRAL upper limits on gamma-ray emission associated with the gravitational wave event GW150914

    Science.gov (United States)

    Savchenko, V.; Ferrigno, C.; Mereghetti, S.; Natalucci, L.; Kuulkers, E.

    2016-06-01

    Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), we put tight upper limits on the gamma-ray and hard X-ray prompt emission associated with the gravitational wave event GW150914, discovered by the LIGO/Virgo collaboration. The omni-directional view of the INTEGRAL/SPI-ACS has allowed us to constrain the fraction of energy emitted in the hard X-ray electromagnetic component for the full high-probability sky region of LIGO/Virgo trigger. Our upper limits on the hard X-ray fluence at the time of the event range from F_{γ}=2 × 10^{-8} erg cm^{-2} to F_{γ}=10^{-6} erg cm^{-2} in the 75 keV - 2 MeV energy range for typical spectral models. Our results constrain the ratio of the energy promptly released in gamma-rays in the direction of the observer to the gravitational wave energy E_γ/E_{GW}limits on the characteristics of the gravitational wave source, based on the available predictions for prompt electromagnetic emission. This work has been possible thanks to a Memorandum of Understanding with the LIGO-Virgo scientific collaboration and is presented on behalf of a larger collaboration.

  9. Beating the spin-down limit on gravitational wave emission from the Vela pulsar

    CERN Document Server

    Abadie, J; Abbott, R; Abernathy, M; Accadia, T; Acernese, F; Adams, C; Adhikari, R; Affeldt, C; Allen, B; Allen, G S; Ceron, E Amador; Amariutei, D; Amin, R S; Anderson, S B; Anderson, W G; Antonucci, F; Arai, K; Arain, M A; Araya, M C; Aston, S M; Astone, P; Atkinson, D; Aufmuth, P; Aulbert, C; Aylott, B E; Babak, S; Baker, P; Ballardin, G; Ballmer, S; Barker, D; Barnum, S; Barone, F; Barr, B; Barriga, P; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Bastarrika, M; Basti, A; Bauchrowitz, J; Bauer, Th S; Behnke, B; Beker, M BejgerM G; Bell, A S; Belletoile, A; Belopolski, I; Benacquista, M; Bertolini, A; Betzwieser, J; Beveridge, N; Beyersdorf, P T; Bilenko, I A; Billingsley, G; Birch, J; Birindelli, S; Biswas, R; Bitossi, M; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bland, B; Blom, M; Bock, O; Bodiya, T P; Bogan, C; Bondarescu, R; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, S; Bosi, L; Bouhou, B; Boyle, M; Braccini, S; Bradaschia, C; Brady, P R; Braginsky, V B; Brau, J E; Breyer, J; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Britzger, M; Brooks, A F; Brown, D A; Brummit, A; Budzyński, R; Bulik, T; Bulten, H J; Buonanno, A; Burguet--Castell, J; Burmeister, O; Buskulic, D; Buy, C; Byer, R L; Cadonati, L; Cagnoli, G; Cain, J; Calloni, E; Camp, J B; Campagna, E; Campsie, P; Cannizzo, J; Cannon, K; Canuel, B; Cao, J; Capano, C; Carbognani, F; Caride, S; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C; Cesarini, E; Chaibi, O; Chalermsongsak, T; Chalkley, E; Charlton, P; Chassande-Mottin, E; Chelkowski, S; Chen, Y; Chincarini, A; Christensen, N; Chua, S S Y; Chung, C T Y; Chung, S; Clara, F; Clark, D; Clark, J; Clayton, J H; Cleva, F; Coccia, E; Colacino, C N; Colas, J; Colla, A; Colombini, M; Conte, R; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Costa, C A; Coughlin, M; Coulon, J -P; Coward, D M; Coyne, D C; Creighton, J D E; Creighton, T D; Cruise, A M; Culter, R M; Cumming, A; Cunningham, L; Cuoco, E; Dahl, K; Danilishin, S L; Dannenberg, R; D'Antonio, S; Danzmann, K; Das, K; Dattilo, V; Daudert, B; Daveloza, H; Davier, M; Davies, G; Daw, E J; Day, R; Dayanga, T; De Rosa, R; DeBra, D; Debreczeni, G; Degallaix, J; del Prete, M; Dent, T; Dergachev, V; DeRosa, R; DeSalvo, R; Dhurandhar, S; Di Fiore, L; Di Lieto, A; Di Palma, I; Emilio, M Di Paolo; Di Virgilio, A; Díaz, M; Dietz, A; Donovan, F; Dooley, K L; Dorsher, S; Douglas, E S D; Drago, M; Drever, R W P; Driggers, J C; Dumas, J -C; Dwyer, S; Eberle, T; Edgar, M; Edwards, M; Effler, A; Ehrens, P; Engel, R; Etzel, T; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fan, Y; Farr, B F; Fazi, D; Fehrmann, H; Feldbaum, D; Ferrante, I; Fidecaro, F; Finn, L S; Fiori, I; Flaminio, R; Flanigan, M; Foley, S; Forsi, E; Forte, L A; Fotopoulos, N; Fournier, J -D; Franc, J; Frasca, S; Frasconi, F; Frede, M; Frei, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Friedrich, D; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Galimberti, M; Gammaitoni, L; Garcia, J; Garofoli, J A; Garufi, F; Gáspár, M E; Gemme, G; Genin, E; Gennai, A; Ghosh, S; Giaime, J A; Giampanis, S; Giardina, K D; Giazotto, A; Gill, C; Goetz, E; Goggin, L M; González, G; Gorodetsky, M L; Goßler, S; Gouaty, R; Graef, C; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Greverie, C; Grosso, R; Grote, H; Grunewald, S; Guidi, G M; Guido, C; Gupta, R; Gustafson, E K; Gustafson, R; Hage, B; Hallam, J M; Hammer, D; Hammond, G; Hanks, J; Hanna, C; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hartman, M T; Haughian, K; Hayama, K; Hayau, J -F; Hayler, T; Heefner, J; Heitmann, H; Hello, P; Hendry, M A; Heng, I S; Heptonstall, A W; Herrera, V; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Holt, K; Hong, T; Hooper, S; Hosken, D J; Hough, J; Howell, E J; Huet, D; Hughey, B; Husa, S; Huttner, S H; Ingram, D R; Inta, R; Isogai, T; Ivanov, A; Jaranowski, P; Johnson, W W; Jones, D I; Jones, G; Jones, R; Ju, L; Kalmus, P; Kalogera, V; Kandhasamy, S; Kanner, J B; Katsavounidis, E; Katzman, W; Kawabe, K; Kawamura, S; Kawazoe, F; Kells, W; Kelner, M; Keppel, D G; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, H; Kim, N; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kondrashov, V; Kopparapu, R; Koranda, S; Korth, W Z; Kowalska, I; Kozak, D; Kringel, V; Krishnamurthy, S; Krishnan, B; Królak, A; Kuehn, G; Kumar, R; Kwee, P; Landry, M; Lantz, B; Lastzka, N; Lazzarini, A; Leaci, P; Leong, J; Leonor, I; Leroy, N; Letendre, N; Li, J; Li, T G F; Liguori, N; Lindquist, P E; Lockerbie, N A; Lodhia, D; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lu, P; Luan, J; Lubinski, M; Lück, H; Lundgren, A P; Macdonald, E; Machenschalk, B; MacInnis, M; Mageswaran, M; Mailand, K; Majorana, E; Maksimovic, I; Man, N; Mandel, I; Mandic, V; Mantovani, M; Marandi, A; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Maros, E; Marque, J; Martelli, F; Martin, I W; Martin, R M; Marx, J N; Mason, K; Masserot, A; Matichard, F; Matone, L; Matzner, R A; Mavalvala, N; McCarthy, R; McClelland, D E; McGuire, S C; McIntyre, G; McKechan, D J A; Meadors, G; Mehmet, M; Meier, T; Melatos, A; Melissinos, A C; Mendell, G; Mercer, R A; Merill, L; Meshkov, S; Messenger, C; Meyer, M S; Miao, H; Michel, C; Milano, L; Miller, J; Minenkov, Y; Mino, Y; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Miyakawa, O; Moe, B; Moesta, P; Mohan, M; Mohanty, S D; Mohapatra, S R P; Moraru, D; Moreno, G; Morgado, N; Morgia, A; Mosca, S; Moscatelli, V; Mossavi, K; Mours, B; Mow--Lowry, C M; Mueller, G; Mukherjee, S; Mullavey, A; Müller-Ebhardt, H; Munch, J; Murray, P G; Nash, T; Nawrodt, R; Nelson, J; Neri, I; Newton, G; Nishida, E; Nishizawa, A; Nocera, F; Nolting, D; Ochsner, E; O'Dell, J; Ogin, G H; Oldenburg, R G; O'Reilly, B; O'Shaughnessy, R; Osthelder, C; Ott, C D; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Page, A; Pagliaroli, G; Palladino, L; Palomba, C; Pan, Y; Pankow, C; Paoletti, F; Papa, M A; Parameswaran, A; Pardi, S; Parisi, M; Pasqualetti, A; Passaquieti, R; Passuello, D; Patel, P; Pathak, D; Pedraza, M; Pekowsky, L; Penn, S; Peralta, C; Perreca, A; Persichetti, G; Phelps, M; Pichot, M; Pickenpack, M; Piergiovanni, F; Pietka, M; Pinard, L; Pinto, I M; Pitkin, M; Pletsch, H J; Plissi, M V; Podkaminer, J; Poggiani, R; Pöld, J; Postiglione, F; Prato, M; Predoi, V; Price, L R; Prijatelj, M; Principe, M; Privitera, S; Prix, R; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Quetschke, V; Raab, F J; Rabeling, D S; Rácz, I; Radkins, H; Raffai, P; Rakhmanov, M; Ramet, C R; Rankins, B; Rapagnani, P; Raymond, V; Re, V; Redwine, K; Reed, C M; Reed, T; Regimbau, T; Reid, S; Reitze, D H; Ricci, F; Riesen, R; Riles, K; Roberts, P; Robertson, N A; Robinet, F; Robinson, C; Robinson, E L; Rocchi, A; Roddy, S; Rolland, L; Rollins, J; Romano, J D; Romano, R; Romie, J H; Rosińska, D; Röver, C; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Sakata, S; Sakosky, M; Salemi, F; Salit, M; Sammut, L; de la Jordana, L Sancho; Sandberg, V; Sannibale, V; Santamaría, L; Santiago-Prieto, I; Santostasi, G; Saraf, S; Sassolas, B; Sathyaprakash, B S; Sato, S; Satterthwaite, M; Saulson, P R; Savage, R; Schilling, R; Schlamminger, S; Schnabel, R; Schofield, R M S; Schulz, B; Schutz, B F; Schwinberg, P; Scott, J; Scott, S M; Searle, A C; Seifert, F; Sellers, D; Sengupta, A S; Sentenac, D; Sergeev, A; Shaddock, D A; Shaltev, M; Shapiro, B; Shawhan, P; Weerathunga, T Shihan; Shoemaker, D H; Sibley, A; Siemens, X; Sigg, D; Singer, A; Singer, L; Sintes, A M; Skelton, G; Slagmolen, B J J; Slutsky, J; Smith, J R; Smith, M R; Smith, N D; Smith, R; Somiya, K; Sorazu, B; Soto, J; Speirits, F C; Sperandio, L; Stefszky, M; Stein, A J; Steinlechner, J; Steinlechner, S; Steplewski, S; Stochino, A; Stone, R; Strain, K A; Strigin, S; Stroeer, A S; Sturani, R; Stuver, A L; Summerscales, T Z; Sung, M; Susmithan, S; Sutton, P J; Swinkels, B; Szokoly, G P; Tacca, M; Talukder, D; Tanner, D B; Tarabrin, S P; Taylor, J R; Taylor, R; Thomas, P; Thorne, K A; Thorne, K S; Thrane, E; Thüring, A; Titsler, C; Tokmakov, K V; Toncelli, A; Tonelli, M; Torre, O; Torres, C; Torrie, C I; Tournefier, E; Travasso, F; Traylor, G; Trias, M; Tseng, K; Turner, L; Ugolini, D; Urbanek, K; Vahlbruch, H; Vaishnav, B; Vajente, G; Vallisneri, M; Brand, J F J van den; Broeck, C Van Den; van der Putten, S; van der Sluys, M V; van Veggel, A A; Vass, S; Vasuth, M; Vaulin, R; Vavoulidis, M; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Veltkamp, C; Verkindt, D; Vetrano, F; Viceré, A; Villar, A E; Vinet, J -Y; Vocca, H; Vorvick, C; Vyachanin, S P; Waldman, S J; Wallace, L; Wanner, A; Ward, R L; Was, M; Wei, P; Weinert, M; Weinstein, A J; Weiss, R; Wen, L; Wen, S; Wessels, P; West, M; Westphal, T; Wette, K; Whelan, J T; Whitcomb, S E; White, D; Whiting, B F; Wilkinson, C; Willems, P A; Williams, H R; Williams, L; Willke, B; Winkelmann, L; Winkler, W; Wipf, C C; Wiseman, A G; Woan, G; Wooley, R; Worden, J; Yablon, J; Yakushin, I; Yamamoto, H; Yamamoto, K; Yang, H; Yeaton-Massey, D; Yoshida, S; Yu, P; Yvert, M; Zanolin, M; Zhang, L; Zhang, Z; Zhao, C; Zotov, N; Zucker, M E; Zweizig, J; Buchner, S; Hotan, A; Palfreyman, J

    2011-01-01

    We present direct upper limits on continuous gravitational wave emission from the Vela pulsar using data from the Virgo detector's second science run. These upper limits have been obtained using three independent methods that assume the gravitational wave emission follows the radio timing. Two of the methods produce frequentist upper limits for an assumed known orientation of the star's spin axis and value of the wave polarization angle of, respectively, $1.9\\ee{-24}$ and $2.2\\ee{-24}$, with 95% confidence. The third method, under the same hypothesis, produces a Bayesian upper limit of $2.1\\ee{-24}$, with 95% degree of belief. These limits are below the indirect {\\it spin-down limit} of $3.3\\ee{-24}$ for the Vela pulsar, defined by the energy loss rate inferred from observed decrease in Vela's spin frequency, and correspond to a limit on the star ellipticity of $\\sim 10^{-3}$. Slightly less stringent results, but still well below the spin-down limit, are obtained assuming the star's spin axis inclination and ...

  10. Current Status of Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES)

    Science.gov (United States)

    Shiotani, M.; Takayanagi, M.

    2009-12-01

    Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) was designed to be aboard the Japanese Experiment Module (JEM) on the International Space Station (ISS) as a collaboration project of Japan Aerospace Exploration Agency (JAXA) and National Institute of Information and Communications Technology (NICT). Mission Objectives are: i) Space demonstration of superconductive mixer and 4-K mechanical cooler for the submillimeter limb-emission sounding, and ii) global observations of atmospheric minor constituents in the stratosphere (O3, HCI, CIO, HO2, HOCI, BrO, O3 isotopes, HNO3, CH3CN, etc), contributing to the atmospheric sciences. The SMILES observation is characterized as aiming at variation and its impact of radical species in the stratosphere. Based on its high sensitivity in detecting atmospheric limb emission of the submillimeter wave range, JEM/SMILES will make measurements on several radical species crucial to the ozone chemistry. It will be launched with H-II Transfer Vehicle (HTV) by the latest version of H-II rocket (H-IIB) on September 10th from Tanegashima Space Center in Japan. In this presentaiton, the up-to-date information of SMILES operation as well as the preliminary result of observation data processing.

  11. Terahertz-wave emission from Bi2212 intrinsic Josephson junctions: a review on recent progress

    Science.gov (United States)

    Kakeya, Itsuhiro; Wang, Huabing

    2016-07-01

    Emission of terahertz (THz) electromagnetic (EM) waves from a high critical temperature (T c) superconductor intrinsic Josephson junction (IJJ) is a new and promising candidate for practical applications of superconducting devices. From the engineering viewpoint, the IJJ THz source is competitive against the present semiconducting THz sources such as quantum cascade lasers (QCLs) and resonance tunnelling diode oscillators because of its broad tunable frequency range and ease of the fabrication process for the device. The emitted EM waves are considered to be coherent because the emission is yielded by synchronisation of thousand stacked IJJs consisting of the mesa device. This synchronisation is peculiar: the resonant frequency of each IJJ is distributed because the cross section of the mesa device is trapezoidal in shape. One of the key features of the synchronisation mechanism is the temperature inhomogeneity of the emitting device. In this topical review, we describe the recent progress in studies of IJJ THz sources with particular emphasis on the relevance of the temperature inhomogeneity to the synchronisation and the emission intensity. This review is of specific interest because the IJJ THz source shows the rich variety of functions due to self-heating which has always been a detrimental feature in the present superconducting devices. Moreover, the thermal managements used for IJJ THz sources will be common with those of other semiconducting devices such as QCLs. In addition, this review is to invite the readers into related research through the detailed descriptions of experimental procedures.

  12. Surface acoustic wave regulated single photon emission from a coupled quantum dot-nanocavity system

    CERN Document Server

    Weiß, Matthias; Reichert, Thorsten; Finley, Jonathan J; Wixforth, Achim; Kaniber, Michael; Krenner, Hubert J

    2016-01-01

    A coupled quantum dot--nanocavity system in the weak coupling regime of cavity quantumelectrodynamics is dynamically tuned in and out of resonance by the coherent elastic field of a $f_{\\rm SAW}\\simeq800\\,\\mathrm{MHz}$ surface acoustic wave. When the system is brought to resonance by the sound wave, light-matter interaction is strongly increased by the Purcell effect. This leads to a precisely timed single photon emission as confirmed by the second order photon correlation function $g^{(2)}$. All relevant frequencies of our experiment are faithfully identified in the Fourier transform of $g^{(2)}$, demonstrating high fidelity regulation of the stream of single photons emitted by the system. The implemented scheme can be directly extended to strongly coupled systems and acoustically drives non-adiabatic entangling quantum gates based on Landau-Zener transitions.

  13. The emission mechanism of THz electromagnetic waves from Bi2212 mesa device

    Science.gov (United States)

    Watanabe, Chiharu; Minami, Hidetoshi; Kitamura, Takeo; Kashiwagi, Takanari; Klemm, Richard; Kadowaki, Kazuo

    From the detailed study of the severe temperature inhomogeneity of the Bi2212 IJJ mesa structure often forming ``hot-spot'' at relatively higher bias current region, while the electromagnetic waves are emitted, multi terminal potential measurement of the mesa device has revealed that the equipotential part of the mesa can only give universal ac-Josephson relationship between the potential difference and the frequency measured by the FT-IR spectrometer, and it is violated as the potential is measured in the region where the hot-spot is formed. This means that the deviation of the emission frequency from the ac-Josephson effect comes from a gradient of the electrical potential distribution. This strongly suggests that the electromagnetic waves at THz frequency may be generated in the superconducting part of the mesa, where the static electric potential is uniform, satisfying the ac-Josephson relation universally no matter how much temperature gradient is.

  14. SHM based on Acoustic Emission and Nonlinear Elastic Wave Spectroscopy with Time Reversal Mirrors

    Czech Academy of Sciences Publication Activity Database

    Převorovský, Zdeněk; Vejvodová, Šárka; Chlada, Milan; Krofta, Josef

    Drážďany: Fraunhofer Institute for Non-Destructive Testing Dresden Branch (IZFP-D), 2010, s. 1-1. ISBN N. [Dresden Aiport Seminar - Recent Trends in SHM and NDE /5./. Drážďany (DE), 03.11.2010-04.11.2010] R&D Projects: GA MPO(CZ) FR-TI1/274 Institutional research plan: CEZ:AV0Z20760514 Keywords : acoustic emission * nonlinear elastic wave spectroscopy * time reversal mirrors * defect detection * aircraft structural health monitoring Subject RIV: BI - Acoustics www.airportseminar.fraunhofer.de

  15. Soft X-ray emission during application of lower hybrid waves on JET

    International Nuclear Information System (INIS)

    In this report, we study the local variation of the integrated X-ray emission between various photon energy ranges corresponding to a Si(Li) diode, when fast electrons are induced by lower hybrid waves. Carbon, oxygen, iron and nickel impurities are considered. The modification of the charge equilibrium of the plasma by fast electrons within the corona model is investigated, and the consequences on the radiated power discussed. Corrections due to multi-ionization and impurity transport are evaluated. The difference of the emitted X-ray power per ion between a maxwellian and a suprathermal distribution can yield also to a significant variation of the integrated X-ray emission. This effect is evaluated for various situations of suprathermal distributions and electronic temperatures. Some simple accomodations of existing diagnostic in JET are then proposed, in order to diagnose the fast electron tail

  16. Experimental investigation of the ionospheric hysteresis effect on the threshold excitation level of the Stimulated Electromagnetic Emission (SEE) during heating at the second electron gyro-harmonic frequency

    Science.gov (United States)

    Samimi, A.; Scales, W.; Cruz, M.; Isham, B.; Bernhardt, P. A.

    2012-12-01

    Recent experimental observations of the stimulated electromagnetic emission (SEE) spectrum during heating at the second electron gyro-harmonic show structures ordered by ion gyro-frequency. The proposed generation mechanism considers parametric decay of a pump upper hybrid/electron Bernstein (UH/EB) wave into another UH/EB and a group of neutralized ion Bernstein waves. The presumption of the proposed mechanism is that the pump electromagnetic wave is converted into the UH/EB wave. This conversion process generates field aligned irregularity which exhibits hysteresis effect. The predicted ionospheric hysteresis effect is studied during the PARS 2012 at HAARP. The preliminary results are presented for the first time. Also, experimental study of the effects of 1) the transmitter beam angle and 2) the transmitter frequency offset relative to the second electron gyro-harmonic frequency on the ion gyro-harmonic structures in the SEE spectrum are provided. The aforementioned observations are compared to the predictions of the analytical model. Possible connection of the SEE spectral features and artificially generated ionospheric descending layer is also discussed

  17. Current status of Superconductive Submillimeter-Wave Limb-Emission Sounder (SMILES)

    Science.gov (United States)

    Shiotani, Masato

    Superconductive Submillimeter-Wave Limb-Emission Sounder (SMILES) was designed to be aboard the Japanese Experiment Module (JEM) on the International Space Station (ISS) as a collaboration project of Japan Aerospace Exploration Agency (JAXA) and National Institute of Information and Communications Technology (NICT). Mission Objectives are: i) Space demonstration of superconductive mixer and 4-K mechanical cooler for the submillimeter limbemission sounding, and ii) global observations of atmospheric minor constituents in the stratosphere (O3, HCI, CIO, HO2, HOCI, BrO, O3 isotopes, HNO3, CH3CN, etc), contributing to the atmospheric sciences. The SMILES observation is characterized as aiming at variation and its impact of radical species in the stratosphere. Based on its high sensitivity in detecting atmospheric limb emission of the submillimeter wave range, JEM/SMILES will make measurements on several radical species crucial to the ozone chemistry (normal O3, isotope O3, ClO, HCl, HOCl, BrO, HO2, and H2O2). The SMILES will also try to observe isotopic composition of ozone. Fabrication of the proto-flight model (PFM) and functional test have been done, and it is aiming at the launch scheduled in 2009 by the H-II Transfer Vehicle (HTV).

  18. Colliding neutron stars Gravitational waves, neutrino emission, and $\\gamma$-ray bursts

    CERN Document Server

    Ruffert, M; Ruffert, Maximilian

    1998-01-01

    Three-dimensional hydrodynamical simulations are presented for the direct head-on or off-center collision of two neutron stars, employing a basically Newtonian PPM code but including the emission of gravitational waves and their back-reaction on the hydrodynamical flow. A physical nuclear equation of state is used that allows us to follow the thermodynamical evolution of the stellar matter and to compute the emission of neutrinos. Predicted gravitational wave signals, luminosities and waveforms, are presented. The models are evaluated for their implications for gamma-ray burst scenarios. We find an extremely luminous outburst of neutrinos with a peak luminosity of more than 4E54 erg/s for several milliseconds. This leads to an efficiency of about 1% for the annihilation of neutrinos with antineutrinos, corresponding to an average energy deposition rate of more than 1E52 erg/s and a total energy of about 1E50 erg deposited in electron-positron pairs around the collision site within 10ms. Although these numbers...

  19. Afterglow emission from pair-loaded blast waves in gamma-ray bursts

    CERN Document Server

    Beloborodov, A M

    2005-01-01

    The MeV radiation front of gamma-ray bursts creates copious e+- pairs as it propagates through an ambient medium. The created pairs enrich the leptonic component of the medium by a large factor at distances R < R_load ~ 10^{16} cm from the burst center. The following blast wave sweeps up the pair-rich medium and then emits the observed afterglow radiation. We find that the afterglow has a "memory" of e+- loading outside R_load. The e+- pairs remain in the swept-up material and slowly cool down by emitting synchrotron radiation. They are likely to dominate the blast-wave emission in IR, optical, and UV bands during the first minutes of the observed afterglow. The expected e+- radiation is described by a simple formula, which is derived analytically and checked by numerical integration of synchrotron emission over the blast material; a suitable Lagrangian formalism is developed for such calculations. The main signature of e+- radiation is its flat ("white") spectrum in a broad range of frequencies from IR to...

  20. A critique of Bernstein's beyond objectivism and relativism: science, hermeneutics, and praxis.

    Science.gov (United States)

    Matusitz, Jonathan; Kramer, Eric

    2011-06-01

    This analysis comments on Bernstein's lack of clear understanding of subjectivity, based on his book, Beyond Objectivism and Relativism: Science, Hermeneutics, and Praxis. Bernstein limits his interpretation of subjectivity to thinkers such as Gadamer and Habermas. The authors analyze the ideas of classic scholars such as Edmund Husserl and Friedrich Nietzsche. Husserl put forward his notion of transcendental subjectivity and phenomenological ramifications of the relationship between subjectivity and objectivity. Nietzsche referred to subjectivity as "perspectivism," the inescapable fact that any and all consciousnesses exist in space and time. Consciousness is fundamentally constituted of cultural, linguistic, and historical dimensions. PMID:21874130

  1. Approximation and Shape Preserving Properties of the Bernstein Operator of Max-Product Kind

    Directory of Open Access Journals (Sweden)

    Barnabás Bede

    2009-01-01

    question of improving the order of approximation 1√(;1/ is raised. The first aim of this note is to obtain this order of approximation but by a simpler method, which in addition presents, at least, two advantages: it produces an explicit constant in front of 1√(;1/ and it can easily be extended to other max-prod operators of Bernstein type. However, for subclasses of functions including, for example, that of concave functions, we find the order of approximation 1(;1/, which for many functions is essentially better than the order of approximation obtained by the linear Bernstein operators. Finally, some shape-preserving properties are obtained.

  2. Hilbert series of graded Milnor algebras and roots of Bernstein-Sato polynomials

    OpenAIRE

    Saito, Morihiko

    2015-01-01

    We show that there is a pair of homogeneous polynomials such that the sets of roots of their Bernstein-Sato polynomials which are strictly supported at the origin are different although the sets of roots which are not strictly supported at the origin are the same and moreover their graded Milnor algebras have the same Hilbert series. This shows that the roots of the Bernstein-Sato polynomials strictly supported at the origin cannot be determined uniquely by the Hilbert series of the Milnor al...

  3. EFFECTS OF ALFVÉN WAVES ON ELECTRON CYCLOTRON MASER EMISSION IN CORONAL LOOPS AND SOLAR TYPE I RADIO STORMS

    International Nuclear Information System (INIS)

    Solar type I radio storms are long-lived radio emissions from the solar atmosphere. It is believed that these type I storms are produced by energetic electrons trapped within a closed magnetic structure and are characterized by a high ordinary (O) mode polarization. However, the microphysical nature of these emissions is still an open problem. Recently, Wu et al. found that Alfvén waves (AWs) can significantly influence the basic physics of wave-particle interactions by modifying the resonant condition. Taking the effects of AWs into account, this work investigates electron cyclotron maser emission driven by power-law energetic electrons with a low-energy cutoff distribution, which are trapped in coronal loops by closed solar magnetic fields. The results show that the emission is dominated by the O mode. It is proposed that this O mode emission may possibly be responsible for solar type I radio storms.

  4. Emission of gravitational waves from binary systems in the galactic center and diffraction by star clusters

    CERN Document Server

    Longo, P; Nucita, A A; De Paolis, F; Ingrosso, G

    2006-01-01

    Binary systems of compact objects are strong emitters of gravitational waves whose amplitude depends on the binary orbital parameters as the component mass, the orbital semi-major axis and eccentricity. Here, in addition to the famous Hulse-Taylor binary system, we have studied the possibility to detect the gravitational wave signal emitted by binary systems at the center of our galaxy. In particular, recent infrared observation of the galactic center have revealed the existence of a cluster of stars each of which appears to orbit the central black hole in $SgrA^*$. For the stars labelled as S2 and S14, we have studied the emitted spectrum of gravitational wave and compare it with the sensitivity threshold of space-based interferometers like Lisa and Astrod. Furthermore, following recent observations, we have considered the possibility that $SgrA^*$ is actually a binary system of massive black holes and calculated the emission spectrum as a function of the system parameters. The diffraction pattern of gravita...

  5. Large-Amplitude Electrostatic Waves Observed at a Supercritical Interplanetary Shock

    Science.gov (United States)

    Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Goetz, K.; Kersten, K.; Kasper, J. C.; Szabo, A.; Wilber, M.

    2010-01-01

    We present the first observations at an interplanetary shock of large-amplitude (> 100 mV/m pk-pk) solitary waves and large-amplitude (approx.30 mV/m pk-pk) waves exhibiting characteristics consistent with electron Bernstein waves. The Bernstein-like waves show enhanced power at integer and half-integer harmonics of the cyclotron frequency with a broadened power spectrum at higher frequencies, consistent with the electron cyclotron drift instability. The Bernstein-like waves are obliquely polarized with respect to the magnetic field but parallel to the shock normal direction. Strong particle heating is observed in both the electrons and ions. The observed heating and waveforms are likely due to instabilities driven by the free energy provided by reflected ions at this supercritical interplanetary shock. These results offer new insights into collisionless shock dissipation and wave-particle interactions in the solar wind.

  6. Parameterization of atmospheric long-wave emissivity in a mountainous site for all sky conditions

    Directory of Open Access Journals (Sweden)

    J. Herrero

    2012-03-01

    Full Text Available Long-wave radiation is an important component of the energy balance of the Earth's surface. The downward component, emitted by the clouds and aerosols in the atmosphere, is rarely measured, and is still not well understood. In mountainous areas, the models existing for its estimation through the emissivity of the atmosphere do not give good results, and worse still in the presence of clouds. In order to estimate this emissivity for any atmospheric state and in a mountainous site, we related it to the screen-level values of temperature, relative humidity and solar radiation. This permitted the obtaining of: (1 a new set of parametric equations and (2 the modification of the Brutsaert's equation for cloudy skies through the calibration of C factor to 0.34 and the parameterization of the cloud index N. Both fitted to the surface data measured at a weather station at a height of 2500 m a.s.l. in Sierra Nevada, Spain. This study analyzes separately three significant atmospheric states related to cloud cover, which were also deduced from the screen-level meteorological data. Clear and totally overcast skies are accurately represented by the new parametric expressions, while the intermediate situations corresponding to partly clouded skies, concentrate most of the dispersion in the measurements and, hence, the error in the simulation. Thus, the modeling of atmospheric emissivity is greatly improved thanks to the use of different equations for each atmospheric state.

  7. Coupled wave-atmosphere-ocean modeling under RCP8.5 emissions during the 21st century

    Science.gov (United States)

    de Vries, Hylke; Semedo, Alvaro; Sterl, Andreas

    2016-04-01

    Most climate models have no explicit treatment of surface ocean waves. As a result, wave climatologies are usually obtained off-line, using atmospheric forcing as input. In recent years attempts have been made to incorporate surface ocean wave models into GCMs, giving the possibility of interactions between components. In the presence of waves the atmospheric winds are modified due to different drag-coefficient and breaking waves will have also influence vertical ocean mixing. As such the waves may play a role in solving long-standing ocean and atmospheric biases. Recently we have coupled the global wave model WAM into EC-Earth GCM (v3.0.1). EC-Earth is based on the IFS atmospheric model and the NEMO/LIM ocean/sea ice model. First results are presented from a 140-year (1961-2100) continuous transient, coupled simulation under RCP8.5 emission scenario. As the modelled climate warms during the transient period, (arctic) sea-ice gradually diminishes, allowing surface waves to penetrate to higher and higher latitudes. Eventually Arctic sea-ice completely disappears in the simulation in late summer. We will discuss swell and wind-wave climatologies, Stokes drift patterns as well as other relevant wave parameters.

  8. Small amplitude variable charge dust Bernstein-Greene-Kruskal double layers

    Energy Technology Data Exchange (ETDEWEB)

    Amour, Rabia [Plasma Physics Group, Theoretical Physics Laboratory, Faculty of Sciences - Physics, U.S.T.H.B, Bab-Ezzouar, B.P. 32, El Alia, Algiers 16111 (Algeria); Tribeche, Mouloud [Plasma Physics Group, Theoretical Physics Laboratory, Faculty of Sciences - Physics, U.S.T.H.B, Bab-Ezzouar, B.P. 32, El Alia, Algiers 16111 (Algeria)], E-mail: mouloud-tribeche@lycos.com

    2009-05-11

    A first theoretical attempt is made to investigate small amplitude, variable charge dust Bernstein-Greene-Kruskal (BGK) double layers (DLs). The nature of the dust BGK-DLs (compressive or rarefactive), their strength and thickness depend sensitively on the net negative charge residing on the grain surface, the dust grain dynamics and, more interestingly, on the ion-to-electron temperatures ratio.

  9. Code Switching and Sexual Orientation: A Test of Bernstein's Sociolinguistic Theory

    Science.gov (United States)

    Lumby, Malcolm E.

    1976-01-01

    Bernstein's theory was tested in the homosexual's "closed" community to determine code-switching ability and its relationship to jargon. Subjects told a story based on homoerotic photographs where knowledge of sexual orientation was varied. Results suggest that homosexual homophyly encouraged elaboration. (Author)

  10. Translation of Bernstein Coefficients Under an Affine Mapping of the Unit Interval

    Science.gov (United States)

    Alford, John A., II

    2012-01-01

    We derive an expression connecting the coefficients of a polynomial expanded in the Bernstein basis to the coefficients of an equivalent expansion of the polynomial under an affine mapping of the domain. The expression may be useful in the calculation of bounds for multi-variate polynomials.

  11. Solving Bernstein's Problem: A Proposal for the Development of Coordinated Movement by Selection.

    Science.gov (United States)

    Sporns, Olaf; Edelman, Gerald M.

    1993-01-01

    In the 1930s, Bernstein pointed out that more than one motor signal can trigger the same physical movement and that identical motor signals can lead to different movements, a dilemma that continues to puzzle scientists. Based on results from computer simulations, posits that these motor signals can be grouped into categories that correspond to…

  12. Iterates of Bernstein Type Operators on a Triangle with All Curved Sides

    Directory of Open Access Journals (Sweden)

    Teodora Cătinaş

    2014-01-01

    Full Text Available We consider some Bernstein-type operators as well as their product and Boolean sum for a function defined on a triangle with all curved sides. Using the weakly Picard operators technique and the contraction principle, we study the convergence of the iterates of these operators.

  13. Iterates of Bernstein Type Operators on a Triangle with All Curved Sides

    OpenAIRE

    Teodora Cătinaş

    2014-01-01

    We consider some Bernstein-type operators as well as their product and Boolean sum for a function defined on a triangle with all curved sides. Using the weakly Picard operators technique and the contraction principle, we study the convergence of the iterates of these operators.

  14. Bispectrum Analysis of Non-linear wave-wave Interaction between VLF Transmitter signal and ELF emission on the Basis of DEMETER satellite observations

    Science.gov (United States)

    Sondhiya, Deepak Kumar; Gwal, Ashok Kumar; Kasde, Satish Kumar

    2016-07-01

    Symmetric sidebands are observed in the ionosphere by the DEMETER (Detection of Electromagnetic Radiation Transmitted through Earthquake Region) satellite, when it passes above the Indian VLF transmitter, named VTX (18.2 kHz), located near Kanyakumari, India. The spectral boarding phenomena may be divided into two types: (1) spectrally broadened components occurring without any association with ELF/VLF emissions under disturbed ionospheric condition, (2) Spectrally broadened components with predominant side band structure in association with ELF emission. Generally spectral analysis at second order (Power spectrum) is used to analyze the frequency component of signal, but it losses the phase information among the different Fourier components. To retain this information the bispectrum (third order) and/or the bicoherence (normalized bispectrum) are used. Results suggest a non-linear mode coupling between the transmitter signal and ELF emission which produces sidebands that are quasi-electrostatic in nature. However, faint spectral broadened components in both types 1 and 2 may be connected with Doppler shift of quasi-electrostatic, whistler mode waves with a broad spectrum near resonance cone, due to scattering of the transmitter signals from ionospheric irregularities in the F-region. Keywords: spectral boarding, wave-wave Interaction, whistler mode waves and Doppler shift

  15. On the rate and on the gravitational wave emission of short and long GRBs

    CERN Document Server

    Ruffini, R; Muccino, M; Pisani, G B; Wang, Y; Becerra, L M; Kovacevic, M; Oliveira, F G; Aimuratov, Y; Bianco, C L; Moradi, R; Rodriguez, J; Barres, U

    2016-01-01

    Short and long-duration gamma-ray bursts (GRBs) are expected to originate in binary systems. For short bursts, we have as possible progenitors neutron star (NS) binaries (NS-NS), or of NS-black hole (BH) binaries (NS-BH). For long bursts, the induced gravitational collapse (IGC) paradigm introduces a tight binary system composed of a carbon-oxygen core (CO$_{\\rm core}$) undergoing supernova (SN) explosion that in turn triggers a hypercritical accretion process onto a NS companion, or onto an already formed BH. These IGC events lead lead either to NS-NS or to NS-BH binaries, the latter formed when the accretion is sufficient to bring the NS to its critical mass. We use recent estimates of the observed rates in X and gamma-rays of the above systems to estimate the gravitational wave emission in all these binaries and their expected detection rate by Advanced LIGO.

  16. Maps of millimeter wave emission from three galactic star-forming regions

    Science.gov (United States)

    Barsony, Mary

    1987-01-01

    In order to investigate the gas dynamics around young stellar objects, three sources were mapped which exhibit supersonic velocities in the 115 GHZ, J = 1-0 transition of CO. The maps, made with the Owens Valley Radio Observatory Millimeter Interferometer, are the highest spatial resolution images currently available of millimeter-wave continuum and line emission from the sources S106, S87, and LkHalpha101. Observations were made in the CS (J = 2-1) and C-13O (J = 1-0) transitions. In all the sources, the observations indicate that the ionized stellar wind is sweeping up ambient molecular gas. The molecular gas is found adjacent to the outer edges of the ionized winds, which originate in embedded infrared sources. From the observations presented, it may be inferred that the outflowing ionized winds are channeled by the surrounding dense, neutral gas.

  17. Satellite observation of plasma-wave disturbances induced by high-power radio emission from the NWC transmitter

    International Nuclear Information System (INIS)

    In this work, we present the results of in-situ measurements of the characteristics of electromagnetic and plasma disturbances in the ionospheric region modified by high-power emission from the NWC transmitter, which were obtained using the onboard equipment of the French microsatellite DEMETER. It is shown that under the influence of VLF emissions from the ground-based transmitters, artificial plasma-wave channels with typical transverse scales of about 1000 km can be formed in the ionospheric plasma.

  18. E.l.f./v.l.f. emissions observed on Ariel 4. [wave-particle phenomena in magnetosphere

    Science.gov (United States)

    Bullough, K.; Denby, M.; Gibbons, W.; Hughes, A. R. W.; Kaiser, T. R.; Tatnall, A. R. L.

    1975-01-01

    The Ariel 4 satellite was designed to study wave-particle phenomena in the magnetosphere by measuring the electromagnetic wave fields over a wide frequency range and the fluxes and pitch angle distributions of energetic particles. We describe here the results of a preliminary study of the various v.l.f./e.l.f. electromagnetic wave phenomena which are observed. These include man-made signals from v.l.f. transmitters, impulsive noise originating in thunderstorms and emissions arising from magnetospheric energetic charged particles.

  19. INTEGRAL upper limits on gamma-ray emission associated with the gravitational wave event GW150914

    Science.gov (United States)

    Savchenko, V.; Ferrigno, C.; Mereghetti, S.; Natalucci, L.; Kuulkers, E.

    2016-06-01

    Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), we put tight upper limits on the gamma-ray and hard X-ray prompt emission associated with the gravitational wave event GW150914, discovered by the LIGO/Virgo collaboration. The omni-directional view of the INTEGRAL/SPI-ACS has allowed us to constrain the fraction of energy emitted in the hard X-ray electromagnetic component for the full high-probability sky region of LIGO/Virgo trigger. Our upper limits on the hard X-ray fluence at the time of the event range from F_{γ}=2 × 10^{-8} erg cm^{-2} to F_{γ}=10^{-6} erg cm^{-2} in the 75 keV - 2 MeV energy range for typical spectral models. Our results constrain the ratio of the energy promptly released in gamma-rays in the direction of the observer to the gravitational wave energy E_γ/E_{GW}work has been possible thanks to a Memorandum of Understanding with the LIGO-Virgo scientific collaboration and is presented on behalf of a larger collaboration.

  20. Double layers and plasma-wave resistivity in extragalactic jets: Cavity formation and radio-wave emission

    Science.gov (United States)

    Borovsky, Joseph E.

    1987-01-01

    For estimated values of the currents carried by extragalactic jets, current-driven electrostatic-wave- and electromagnetic-wave-produced resistivities do not occur. Strong plasma double layers, however, may exist within self-maintained density cavities, the relativistic double-layer-emitted electron, and ion beams driving plasma-wave resistivities in the low- and high-potential plasma adjacent to the double layers. The double-layer-emitted electron beams may also emit polarized radio waves via a collective bremsstrahlung process mediated by electrostatic two-stream instabilities.

  1. Double layers and plasma-wave resistivity in extragalactic jets - Cavity formation and radio-wave emission

    Science.gov (United States)

    Borovsky, Joseph E.

    1987-01-01

    Current driven electrostatic-wave- and electromagnetic-wave-produced resistivities do not occur in extragalactic jets for estimated values of the carried currents. Strong plasma double layers, however, may exist within self-maintained density cavities. The relativistic double-layer-emitted electron and ion beams drive plasma-wave resistivities in the low- and high-potential plasma adjacent to the double layers. The double-layer-emitted electron beams may also emit polarized radio waves via a collective bremsstrahlung process mediated by electrostatic two-stream instabilities.

  2. Gravity Wave Energetics Determined From Coincident Space-Based and Ground-Based Observations of Airglow Emissions

    Science.gov (United States)

    2000-01-01

    Significant progress was made toward the goals of this proposal in a number of areas during the covered period. Section 5.1 contains a copy of the originally proposed schedule. The tasks listed below have been accomplished: (1) Construction of space-based observing geometry gravity wave model. This model has been described in detail in the paper accompanying this report (Section 5.2). It can simulate the observing geometry of both ground-based, and orbital instruments allowing comparisons to be made between them. (2) Comparisons of relative emission intensity, temperatures, and Krassovsky's ratio for space- and ground-based observing geometries. These quantities are used in gravity wave literature to describe the effects of the waves on the airglow. (3) Rejection of Bates [1992], and Copeland [1994] chemistries for gravity wave modeling purposes. Excessive 02(A(sup 13)(Delta)) production led to overproduction of O2(b(sup 1)(Sigma)), the state responsible for the emission of O2. Atmospheric band. Attempts were made to correct for this behavior, but could not adequately compensate for this. (4) Rejection of MSX dataset due to lack of coincident data, and resolution necessary to characterize the waves. A careful search to identify coincident data revealed only four instances, with only one of those providing usable data. Two high latitude overpasses and were contaminated by auroral emissions. Of the remaining two mid-latitude coincidences, one overflight was obscured by cloud, leaving only one ten minute segment of usable data. Aside from the statistical difficulties involved in comparing measurements taken in this short period, the instrument lacks the necessary resolution to determine the vertical wavelength of the gravity wave. This means that the wave cannot be uniquely characterized from space with this dataset. Since no observed wave can be uniquely identified, model comparisons are not possible.

  3. Spectral-temporal description of dispersive wave emission and soliton trapping in micro-nano silicon-on-insulator waveguides

    Science.gov (United States)

    Wen, Jin; Ma, Chengju; Fan, Wei; Fu, Haiwei

    2015-08-01

    We numerically investigate the dispersive wave emission and soliton trapping in the process of femtosecond soliton propagation in silicon-on-insulator (SOI) waveguide. The cross-correlation frequency resolved optical gating (X-FROG) technique is employed to analyze the spectral-temporal dynamics of the soliton at different propagation distances. The numerical results show that dispersive wave emission can be blue-shifted (around 1300 nm) or red-shifted (around 1900 nm), which is determined by the dispersion slope for the pump wavelength (1550 nm). In addition, it can be found that red-shifted dispersive wave can supply contribution to the flatness of the supercontinuum generation. Through increasing the peak power of the soliton to 100 W, the soliton trapping can be observed by the edge of dispersive wave, which can be visualized in the form of multi-peak oscillation structure in the spectrogram when not considering the two-photon absorption (TPA). This work opens up the possibility for the realization of dispersive wave emission device in highly integrated circuit.

  4. Dispersive wave emission and supercontinuum generation in a silicon wire waveguide pumped around the 1550 nm telecommunication wavelength

    CERN Document Server

    Leo, François; Safioui, Jassem; Kockaert, Pascal; Coen, Stéphane; Dave, Utsav; Kuyken, Bart; Roelkens, Gunther

    2014-01-01

    We demonstrate dispersive wave generation, soliton fission and supercontinuum generation in a silicon wire at telecom wavelengths. Despite the strong nonlinear absorption inherent to silicon at telecom wavelengths, we experimentally demonstrate that the compression and subsequent splitting of higher order solitons remains possible. Moreover we observe the emission of resonant radiation from the solitons, leading to the generation a broad supercontinuum.

  5. INTEGRAL Upper Limits on Gamma-Ray Emission Associated with the Gravitational Wave Event GW150914

    DEFF Research Database (Denmark)

    Savchenko, V.; Ferrigno, C.; Mereghetti, S.;

    2016-01-01

    Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), we place upper limits on the gamma-ray and hard X-ray prompt emission associated with the gravitational wave event GW150914, which was discovered by the LIGO/Virgo Collaboration. The omnidirectional view of the...... the 75 keV-2 MeV energy range for typical spectral models. Our results constrain the ratio of the energy promptly released in gamma-rays in the direction of the observer to the gravitational wave energy Eγ/EGW <10-6. We discuss the implication of gamma-ray limits for the characteristics of the...... gravitational wave source, based on the available predictions for prompt electromagnetic emission....

  6. Electron Bernstein Driven and Bootstrap Current Estimations in the TJ-II Stellarator

    International Nuclear Information System (INIS)

    Full text: The control of the total parallel current may lead to the possibility of continuous operation in tokamak plasmas and it can provide access to improved confinement regimes in stellarators, by means of control of the rotational transform profile. In fact one of the main lines of research at the stellarator TJ-II is the relation between confinement and the magnetic configuration, putting emphasis on the rotational transform profile. The two main non-inductive parallel currents in plasma confinement devices are the bootstrap and the ones driven by external means, like radio frequency or NBI. The current drive (CD) systems must be appropriated to work on overdense plasmas, since this could be mandatory in a reactor. Therefore, electron Bernstein waves (EBW), which do not present density cut-off have been considered as CD system for TJ-II. In this work we present calculations of the bootstrap and the EBW currents in the dense plasmas confined in a complex 3D confinement device like the TJ-II stellarator. The precise calculation of the bootstrap current is a numerical challenge, since the error estimates for computations of this current, specially in the long-mean-free-path (lmfp) regime of stellarators, are very large. This issue is particularly relevant for the lmfp regime of stellarators, particularly for TJ-II, which is characterized by its very complex magnetic configuration. A new code, NEO-MC, has been developed in order to overcome this problem. It combines the standard δf method with an algorithm employing constant particle weights and re-discretizations of the test particle distribution. In this way, it is able to provide, for the first time, calculations of the contribution of the lmfp regime to the bootstrap current of TJ-II with very low error estimates. For a fast estimation of EBCD, different linear models based on the adjoint approach or Langevin equations techniques have been developed in order to simplify the task of solving the kinetic

  7. Nonlinear Landau damping and formation of Bernstein-Greene-Kruskal structures for plasmas with q-nonextensive velocity distributions

    Science.gov (United States)

    Raghunathan, M.; Ganesh, R.

    2013-03-01

    In the past, long-time evolution of an initial perturbation in collisionless Maxwellian plasma (q = 1) has been simulated numerically. The controversy over the nonlinear fate of such electrostatic perturbations was resolved by Manfredi [Phys. Rev. Lett. 79, 2815-2818 (1997)] using long-time simulations up to t = 1600 ωp - 1 . The oscillations were found to continue indefinitely leading to Bernstein-Greene-Kruskal (BGK)-like phase-space vortices (from here on referred as "BGK structures"). Using a newly developed, high resolution 1D Vlasov-Poisson solver based on piecewise-parabolic method (PPM) advection scheme, we investigate the nonlinear Landau damping in 1D plasma described by toy q-distributions for long times, up to t = 3000 ωp - 1 . We show that BGK structures are found only for a certain range of q-values around q = 1. Beyond this window, for the generic parameters, no BGK structures were observed. We observe that for values of q 1 where distribution has a sharp fall in velocity, the formation of BGK structures is rendered difficult due to high wave number damping imposed by the steep velocity profile, which had not been previously reported. Wherever relevant, we compare our results with past work.

  8. Effect of Alfvén waves on the growth rate of the electron-cyclotron maser emission

    Energy Technology Data Exchange (ETDEWEB)

    Wu, D. J., E-mail: djwu@pmo.ac.cn [Purple Mountain Observatory, CAS, Nanjing 210008 (China)

    2014-06-15

    By using the non-relativistic approximation for the calculation of growth rates, but taking account of the weakly relativistic modification for the electron-cyclotron resonance condition, it is shown that the effect of Alfvén waves (AWs) on the electron-cyclotron maser emission leads to the significant increase of the O-mode growth rate, but has little effect on the X-mode growth rate. We propose that this is because the O-mode wave has the field-aligned polarization sense in the same as the field-aligned oscillatory current, which is created by the field-aligned oscillatory motion of the energetic electrons caused via the presence of AWs. It is this field-aligned oscillatory current that contributes a novel growth rate to the O-mode wave but has little effect on the X-mode wave.

  9. A spinning mirror for fast angular scans of EBW emission for magnetic pitch profile measurements

    International Nuclear Information System (INIS)

    A tilted spinning mirror rapidly steers the line of sight of the electron Bernstein wave (EBW) emission radiometer at the Mega-Amp Spherical Tokamak (MAST). In order to resist high mechanical stresses at rotation speeds of up to 12 000 rpm and to avoid eddy current induced magnetic braking, the mirror consists of a glass-reinforced nylon substrate of a special self-balanced design, coated with a reflecting layer. By completing an angular scan every 2.5-10 ms, it allows one to characterize with good time resolution the Bernstein-extraordinary-ordinary mode-conversion efficiency as a function of the view angles. Angular maps of conversion efficiency are directly related to the magnetic pitch angle at the cutoff layer for the ordinary mode. Hence, measurements at various frequencies provide the safety factor profile at the plasma edge. Initial measurements and indications of the feasibility of the diagnostic are presented. Moreover, angular scans indicate the best launch conditions for EBW heating.

  10. A parametric study for the generation of ion Bernstein modes from a discrete spectrum to a continuous one in the inner magnetosphere. I. Linear theory

    Science.gov (United States)

    Sun, Jicheng; Gao, Xinliang; Chen, Lunjin; Lu, Quanming; Tao, Xin; Wang, Shui

    2016-02-01

    Ion Bernstein modes, also known as magnetosonic waves in the magnetospheric community, are considered to play an important role in radiation belt electron acceleration. The detailed properties of perpendicular magnetosonic waves excited in the inner magnetosphere by a tenuous proton ring distribution are investigated in a two series paper with a combination of the linear theory and one-dimensional particle-in-cell simulations. Here, in this paper, we study the properties of the excited magnetosonic waves under different plasma conditions with the linear theory. When the proton to electron mass ratio or the ratio of the light speed to the Alfven speed is small, the excited magnetosonic waves are prone to having a discrete spectrum with only several wave modes. With the increase of the proton to electron mass ratio or the ratio of the light speed to the Alfven speed, the lower hybrid frequency also increases, which leads to the increase of both the number and frequency of the excited wave modes. Meanwhile, the growth rate of these wave modes also increases. When the proton to electron mass ratio or the ratio of the light speed to the Alfven speed is sufficiently large, the spectrum of the excited magnetic waves becomes continuous due to the overlapping of the adjacent wave modes. The increase of the density of the protons with the ring distribution can also result in the increase of the growth rate, which may also change the discrete spectrum of the excited waves to a continuous one, while the increase of the ring velocity of the tenuous proton ring distribution leads to a broader spectrum, but with a smaller growth rate.

  11. The collective emission of electromagnetic waves from astrophysical jets - Luminosity gaps, BL Lacertae objects, and efficient energy transport

    Science.gov (United States)

    Baker, D. N.; Borovsky, Joseph E.; Benford, Gregory; Eilek, Jean A.

    1988-01-01

    A model of the inner portions of astrophysical jets is constructed in which a relativistic electron beam is injected from the central engine into the jet plasma. This beam drives electrostatic plasma wave turbulence, which leads to the collective emission of electromagnetic waves. The emitted waves are beamed in the direction of the jet axis, so that end-on viewing of the jet yields an extremely bright source (BL Lacertae object). The relativistic electron beam may also drive long-wavelength electromagnetic plasma instabilities (firehose and Kelvin-Helmholtz) that jumble the jet magnetic field lines. After a sufficient distance from the core source, these instabilities will cause the beamed emission to point in random directions and the jet emission can then be observed from any direction relative to the jet axis. This combination of effects may lead to the gap turn-on of astrophysical jets. The collective emission model leads to different estimates for energy transport and the interpretation of radio spectra than the conventional incoherent synchrotron theory.

  12. Validation of ozone data from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES)

    Science.gov (United States)

    Imai, Koji; Manago, Naohiro; Mitsuda, Chihiro; Naito, Yoko; Nishimoto, Eriko; Sakazaki, Takatoshi; Fujiwara, Masatomo; Froidevaux, Lucien; Clarmann, Thomas; Stiller, Gabriele P.; Murtagh, Donal P.; Rong, Ping-Ping; Mlynczak, Martin G.; Walker, Kaley A.; Kinnison, Douglas E.; Akiyoshi, Hideharu; Nakamura, Tetsu; Miyasaka, Takayuki; Nishibori, Toshiyuki; Mizobuchi, Satoko; Kikuchi, Ken-Ichi; Ozeki, Hiroyuki; Takahashi, Chikako; Hayashi, Hiroo; Sano, Takuki; Suzuki, Makoto; Takayanagi, Masahiro; Shiotani, Masato

    2013-06-01

    The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) onboard the International Space Station provided global measurements of ozone profiles in the middle atmosphere from 12 October 2009 to 21 April 2010. We present validation studies of the SMILES version 2.1 ozone product based on coincidence statistics with satellite observations and outputs of chemistry and transport models (CTMs). Comparisons of the stratospheric ozone with correlative data show agreements that are generally within 10%. In the mesosphere, the agreement is also good and better than 30% even at a high altitude of 73 km, and the SMILES measurements with their local time coverage also capture the diurnal variability very well. The recommended altitude range for scientific use is from 16 to 73 km. We note that the SMILES ozone values for altitude above 26 km are smaller than some of the correlative satellite datasets; conversely the SMILES values in the lower stratosphere tend to be larger than correlative data, particularly in the tropics, with less than 8% difference below ~24 km. The larger values in the lower stratosphere are probably due to departure of retrieval results between two detection bands at altitudes below 28 km; it is ~3% at 24 km and is increasing rapidly down below.

  13. Continuous-Wave Stimulated Emission Depletion Microscope for Imaging Actin Cytoskeleton in Fixed and Live Cells

    Directory of Open Access Journals (Sweden)

    Bhanu Neupane

    2015-09-01

    Full Text Available Stimulated emission depletion (STED microscopy provides a new opportunity to study fine sub-cellular structures and highly dynamic cellular processes, which are challenging to observe using conventional optical microscopy. Using actin as an example, we explored the feasibility of using a continuous wave (CW-STED microscope to study the fine structure and dynamics in fixed and live cells. Actin plays an important role in cellular processes, whose functioning involves dynamic formation and reorganization of fine structures of actin filaments. Frequently used confocal fluorescence and STED microscopy dyes were employed to image fixed PC-12 cells (dyed with phalloidin- fluorescein isothiocyante and live rat chondrosarcoma cells (RCS transfected with actin-green fluorescent protein (GFP. Compared to conventional confocal fluorescence microscopy, CW-STED microscopy shows improved spatial resolution in both fixed and live cells. We were able to monitor cell morphology changes continuously; however, the number of repetitive analyses were limited primarily by the dyes used in these experiments and could be improved with the use of dyes less susceptible to photobleaching. In conclusion, CW-STED may disclose new information for biological systems with a proper characteristic length scale. The challenges of using CW-STED microscopy to study cell structures are discussed.

  14. Directed searches for broadband extended gravitational-wave emission in nearby energetic core-collapse supernovae

    CERN Document Server

    Van Putten, Maurice H P M

    2016-01-01

    Core-collapse supernovae are factories of neutron stars and stellar mass black holes. Type Ib/c supernovae stand out as potentially originating in relatively compact stellar binaries and their branching ratio of about 1\\% into long gamma-ray bursts. The most energetic events probably derive from central engines harboring rapidly rotating black holes, wherein accretion of fall-back matter down to the Inner Most Stable Circular Orbit (ISCO) offers a window to {\\em broadband extended gravitational-wave emission} (BEGE). To search for BEGE, we introduce a butterfly filter in time-frequency space by Time Sliced Matched Filtering. To analyze long epochs of data, we propose using coarse grained searches followed by high resolution searches on events of interest. We illustrate our proposed coarse grained search on two weeks of LIGO S6 data prior to SN 2010br $(z=0.002339)$ using a bank of up to 64 thousand templates of one second duration covering a broad range in chirp frequencies and bandwidth. Correlating events w...

  15. Directed Searches for Broadband Extended Gravitational Wave Emission in Nearby Energetic Core-collapse Supernovae

    Science.gov (United States)

    van Putten, Maurice H. P. M.

    2016-03-01

    Core-collapse supernovae (CC-SNe) are factories of neutron stars and stellar-mass black holes. SNe Ib/c stand out as potentially originating in relatively compact stellar binaries and they have a branching ratio of about 1% into long gamma-ray bursts. The most energetic events probably derive from central engines harboring rapidly rotating black holes, wherein the accretion of fall-back matter down to the innermost stable circular orbit (ISCO) offers a window into broadband extended gravitational wave emission (BEGE). To search for BEGE, we introduce a butterfly filter in time-frequency space by time-sliced matched filtering. To analyze long epochs of data, we propose using coarse-grained searches followed by high-resolution searches on events of interest. We illustrate our proposed coarse-grained search on two weeks of LIGO S6 data prior to SN 2010br (z = 0.002339) using a bank of up to 64,000 templates of one-second duration covering a broad range in chirp frequencies and bandwidth. Correlating events with signal-to-noise ratios > 6 from the LIGO L1 and H1 detectors reduces the total to a few events of interest. Lacking any further properties reflecting a common excitation by broadband gravitational radiation, we disregarded these as spurious. This new pipeline may be used to systematically search for long-duration chirps in nearby CC-SNe from robotic optical transient surveys using embarrassingly parallel computing.

  16. Research on the decreased resistance of concrete under traction by detection of stress wave emission

    International Nuclear Information System (INIS)

    The recording of the cumulated stress wave emission counting from a concrete specimen under increasing load shows angular points which appear at well-defined fractions of the breaking strength and mark the limits of 4 distinct phases: compression stage for: 0

  17. Investigation of a shock wave in an arcjet He plasma by using an electric probe and emission spectroscope

    Energy Technology Data Exchange (ETDEWEB)

    Kumagawa, G.; Kozue, K.; Fujino, S.; Matsuoka, L.; Endo, T.; Namba, S. [Hiroshima University, Higashi-Hiroshima (Japan); Tamura, N. [National Institute for Fusion Science, Gifu (Japan); Ezumi, N. [Nagano National College of Technology, Nagano (Japan)

    2014-10-15

    We developed an arcjet plasma device having a converging and diverging supersonic conical nozzle. Bright and dark emission structures were formed, depending on the gas pressure in the expansion section. In order to understand the mechanism for the formation of the structures, we evaluated the plasma parameters (electron density and temperature) by using a single probe and a visible emission spectroscope. The analysis of the probe measurements showed no temperature variation around the bright emission region. The plasma density increased significantly by a factor of two. Similar trends were also observed in the spectroscopic measurements. Moreover, the cell width (wavelength) of the shock wave calculated from the compressible fluid dynamics was in good agreement with the experimental value, indicating that this emission structure was caused by a shock cell that could be described by using compressible flow dynamics.

  18. Simultaneous observations of quasi-periodic ELF/VLF wave emissions and electron precipitation by DEMETER satellite: A case study

    Czech Academy of Sciences Publication Activity Database

    Hayosh, Mykhaylo; Pasmanik, D. L.; Demekhov, A. G.; Santolík, Ondřej; Parrot, M.; Titova, E. E.

    2013-01-01

    Roč. 118, č. 7 (2013), s. 4523-4533. ISSN 2169-9380 R&D Projects: GA ČR(CZ) GAP209/11/2280; GA MŠk LH12231 Institutional support: RVO:68378289 Keywords : quasi-periodic ELF/VLF emissions in the magnetosphere * wave-particle interactions * demeter spacecraft measurements * whistler-mode waves Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.440, year: 2013 http://onlinelibrary.wiley.com/doi/10.1002/jgra.50179/abstract

  19. Investigation on empowering one direction emission of guided waves to avoid undesired reflections from other pipe attachments

    Science.gov (United States)

    Tse, Peter W.; Zhou, Fang

    2016-02-01

    An in-service pipe always contains elbows and joints at the ends of the pipe. Since the emitted guided waves from a transducer array is bi-directional, any attachments located at both ends of the pipe will cause reflections. For building pipes that are partially covered by wall, the transducer array must be installed near one end of the pipe. If there is elbow or joint connected to that end of the pipe, high reflections generated from the elbow or joint are inevitable. Such reflections may interfere the detection of reflections caused by true defect exists along the pipe body. Hence, to minimize such undesired interference, one must employs some smart devices or algorithms so that it can reduce the emission of guided wave from one direction but enhance the emission from the other direction. To achieve such purpose, two identical transducer arrays must be installed on the same pipe but with a smartly and specially calculated distance apart from the mounting locations of these two arrays. The distance is to ensure there is a proper time delay for emitting the second array after the emission of the first array. The designed processes are listed as follow. Firstly, two identical transducer arrays that could emit L(0,1) guided waves were mounted on a pipe with a specific distance apart from their mounting locations. The distance was determined after calculating the necessary time delay. Secondly, the guided waves generated from the two arrays are combined together to create the desired superimposing effect. With the help of simulation and finite element analysis, such single direction guided wave was successfully generated and tested. By accurately adjusted the time delay, results showed that it is possible to minimize the emitted guided waves in one direction and then empower the guided waves in another direction. Hence, the reflections generated from elbows and joints at one end of the pipe has been minimized, whilst, the emission of guided wave in the other direction

  20. Recent Observations and Modeling of Narrowband Stimulated Electromagnetic Emissions SEEs at HAARP and EISCAT

    Science.gov (United States)

    Scales, W.; Mahmoudian, A.; Fu, H.; Bordikar, M. R.; Samimi, A.; Bernhardt, P. A.; Briczinski, S. J., Jr.; Kosch, M. J.; Senior, A.; Isham, B.

    2014-12-01

    There has been significant interest in so-called narrowband Stimulated Electromagnetic Emission SEE over the past several years due to recent discoveries at the High Frequency Active Auroral Research Program HAARP facility near Gakone, Alaska. Narrowband SEE (NSEE) has been defined as spectral features in the SEE spectrum typically within 1 kHz of the transmitter (or pump) frequency. SEE is due to nonlinear processes leading to re-radiation at frequencies other than the pump wave frequency during heating the ionospheric plasma with high power HF radio waves. Although NSEE exhibits a richly complex structure, it has now been shown after a substantial number of observations at HAARP, that NSEE can be grouped into two basic classes. The first are those spectral features, associated with Stimulated Brillouin Scatter SBS, which typically occur when the pump frequency is not close to electron gyro-harmonic frequencies. Typically, these spectral features are within roughly 50 Hz of the pump wave frequency where it is to be noted that the O+ ion gyro-frequency is roughly 50 Hz. The second class of spectral features corresponds to the case when the pump wave frequency is typically within roughly 10 kHz of electron gyro-harmonic frequencies. In this case, spectral features ordered by harmonics of ion gyro-frequencies are typically observed, and termed Stimulated Ion Bernstein Scatter SIBS. This presentation will first provide an overview of the recent NSEE experimental observations at HAARP. Both Stimulated Brillouin Scatter SBS and Stimulated Ion Bernstein Scatter SIBS observations will be discussed as well as their relationship to each other. Possible theoretical formulation in terms of parametric decay instabilities and computational modeling will be provided. Possible applications of NSEE will be pointed out including triggering diagnostics for artificial ionization layer formation, proton precipitation event diagnostics, electron temperature measurements in the heated

  1. Dynamic control of the optical emission from GaN/InGaN nanowire quantum dots by surface acoustic waves

    Energy Technology Data Exchange (ETDEWEB)

    Lazić, S., E-mail: lazic.snezana@uam.es; Chernysheva, E.; Meulen, H. P. van der; Calleja Pardo, J. M. [Departamento de Física de Materiales, Instituto “Nicolás Cabrera” and Instituto de Física de Materia Condensada (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid (Spain); Gačević, Ž.; Calleja, E. [ISOM-DIE, Universidad Politécnica de Madrid, 28040 Madrid (Spain)

    2015-09-15

    The optical emission of InGaN quantum dots embedded in GaN nanowires is dynamically controlled by a surface acoustic wave (SAW). The emission energy of both the exciton and biexciton lines is modulated over a 1.5 meV range at ∼330 MHz. A small but systematic difference in the exciton and biexciton spectral modulation reveals a linear change of the biexciton binding energy with the SAW amplitude. The present results are relevant for the dynamic control of individual single photon emitters based on nitride semiconductors.

  2. Dynamic control of the optical emission from GaN/InGaN nanowire quantum dots by surface acoustic waves

    International Nuclear Information System (INIS)

    The optical emission of InGaN quantum dots embedded in GaN nanowires is dynamically controlled by a surface acoustic wave (SAW). The emission energy of both the exciton and biexciton lines is modulated over a 1.5 meV range at ∼330 MHz. A small but systematic difference in the exciton and biexciton spectral modulation reveals a linear change of the biexciton binding energy with the SAW amplitude. The present results are relevant for the dynamic control of individual single photon emitters based on nitride semiconductors

  3. Tracking the CME-driven shock wave on 2012 March 5 and radio triangulation of associated radio emission

    International Nuclear Information System (INIS)

    We present a multiwavelength study of the 2012 March 5 solar eruptive event, with an emphasis on the radio triangulation of the associated radio bursts. The main points of the study are reconstruction of the propagation of shock waves driven by coronal mass ejections (CMEs) using radio observations and finding the relative positions of the CME, the CME-driven shock wave, and its radio signatures. For the first time, radio triangulation is applied to different types of radio bursts in the same event and performed in a detailed way using goniopolarimetric observations from STEREO/Waves and WIND/Waves spacecraft. The event on 2012 March 5 was associated with a X1.1 flare from the NOAA AR 1429 situated near the northeast limb, accompanied by a full halo CME and a radio event comprising long-lasting interplanetary type II radio bursts. The results of the three-dimensional reconstruction of the CME (using SOHO/LASCO, STEREO COR, and HI observations), and modeling with the ENLIL cone model suggest that the CME-driven shock wave arrived at 1 AU at about 12:00 UT on March 7 (as observed by SOHO/CELIAS). The results of radio triangulation show that the source of the type II radio burst was situated on the southern flank of the CME. We suggest that the interaction of the shock wave and a nearby coronal streamer resulted in the interplanetary type II radio emission.

  4. Doppler effect in a solid medium: Spin wave emission by a precessing domain wall drifting in spin current

    Science.gov (United States)

    Xia, Hong; Chen, Jie; Zeng, Xiaoyan; Yan, Ming

    2016-04-01

    The Doppler effect is a fundamental physical phenomenon observed for waves propagating in vacuum or various media, commonly gaseous or liquid. Here, we report on the occurrence of a Doppler effect in a solid medium. Instead of a real object, a topological soliton, i.e., a magnetic domain wall (DW) traveling in a current-carrying ferromagnetic nanowire, plays the role of the moving wave source. The Larmor precession of the DW in an external field stimulates emission of monochromatic spin waves (SWs) during its motion, which show a significant Doppler effect, comparable to the acoustic one of a train whistle. This process involves two prominent spin-transfer-torque effects simultaneously, the current-driven DW motion and the current-induced SW Doppler shift. The latter gives rise to an interesting feature, i.e., the observed SW Doppler effect appears resulting from a stationary source and a moving observer, contrary to the laboratory frame.

  5. Influence of field emission on the propagation of cylindrical fast ionization wave in atmospheric-pressure nitrogen

    Science.gov (United States)

    Levko, Dmitry; Raja, Laxminarayan L.

    2016-04-01

    The influence of field emission of electrons from surfaces on the fast ionization wave (FIW) propagation in high-voltage nanosecond pulse discharge in the atmospheric-pressure nitrogen is studied by a one-dimensional Particle-in-Cell Monte Carlo Collisions model. A strong influence of field emission on the FIW dynamics and plasma parameters is obtained. Namely, the accounting for the field emission makes possible the bridging of the cathode-anode gap by rather dense plasma (˜1013 cm-3) in less than 1 ns. This is explained by the generation of runaway electrons from the field emitted electrons. These electrons are able to cross the entire gap pre-ionizing it and promoting the ionization wave propagation. We have found that the propagation of runaway electrons through the gap cannot be accompanied by the streamer propagation, because the runaway electrons align the plasma density gradients. In addition, we have obtained that the field enhancement factor allows controlling the speed of ionization wave propagation.

  6. Emission of whistler-mode waves and diffusion of electrons around interplanetary shocks

    International Nuclear Information System (INIS)

    We present a study of whistler-mode wave generation and wave particle interaction in the vicinity of interplanetary shocks in the ecliptic plane, as observed by the Ulysses spacecraft. Generally the whistler-mode waves (measured in the frequency range 0.22-448 Hz) are observed downstream of the shocks where they persist for some hours. From the electron distribution functions (EDF) in the energy range 1.6 to 862 eV, we compute the temperature anisotropy and the wave growth rate of the electromagnetic electron cyclotron instability for the case of parallel propagation of the waves with respect to the interplanetary magnetic field (IMF) B. In general, in agreement with the wave measurements, the instability grows only downstream of the shock fronts. Following the wave activity, velocity space diffusion of the electrons results in a marginally stable state with sporadic fluctuations

  7. The Supernova Blast Wave and the Molecular Cloud: an Observational Study of Molecular Shock Emission.

    Science.gov (United States)

    Richter, Matthew Joseph

    1995-01-01

    Shock waves in molecular clouds heat, compress, accelerate, and chemically alter the gas they encounter. Despite their crucial role in determining the physical state of the dense interstellar medium and despite their making possible direct observations of H_2, molecular shocks are still poorly understood, as evidenced by the many discrepancies between theory and observations. In my dissertation, I use the supernova remnant IC 443 as a laboratory to test our understanding of shock -excited H_2 emission. By examining roughly 20 separate 2-4 μm Ha transitions, I find the non-uniform temperature structure essentially reproduces that found in Orion Peak 1, and so is consistent with the partially dissociating J-shock model presented by Brand and collaborators. Subsequent mid-infrared observations of the pure rotational S(2) transition at 12 mu m strengthens these conclusions. Velocity resolved line profiles of the strong 1-0 S(1) transition uncover a relationship between the remnant's large-scale geometry and the line profile's full-width at 10% intensity, centroid, and shape. The relationship contradicts any model requiring local bow geometries to explain broad H_2 line widths. Comparing the 1-0 S(1) data with similar observations of the 2-1 S(1) line, I demonstrate that the excitation temperature in the shocked gas depends primarily on position, not velocity. Taken together, the identical velocity extent of the 1-0 S(1) and the 2-1 S(1) lines and their upper state energy separation of E/k ~ 6000 K proves the H_2 -emitting gas reaches its full velocity dispersion prior to cooling below roughly 1500 K. Finally, I compare, with similar spatial and spectral resolution, H_2 and HCO^+ J = 1 - 0 and find evidence for temperature gradients as a result of both preshock density inhomogeneities and postshock cooling.

  8. Development of superconducting submillimeter-wave limb emission sounder (JEM/SMILES) aboard the International Space Station

    Science.gov (United States)

    Ozeki, Hiroyuki; Inatani, Junji; Satoh, Ryouta; Nishibori, Toshiyuki; Ikeda, Naomi; Fujii, Yasunori; Nakajima, Takashi; Iida, Yukiei; Iida, Teruhito; Kikuchi, Ken'ichi; Miura, Takeshi; Masuko, Harunobu; Manabe, Takeshi; Ochiai, Satoshi; Seta, Masumichi; Irimajiri, Yoshihisa; Kasai, Yasuko; Suzuki, Makoto; Shirai, Tomoko; Tsujimaru, Sho; Shibasaki, Kazuo; Shiotani, Masato

    2001-12-01

    A submillimeter wave limb emission sounder, that is to be aboard the Japanese Experiment Module (JEM, dubbed as 'KIBO') at the International Space Station, has been designed. This payload, Superconducting Submillimeter-wave Limb Emission Sounder (SMILES), is aimed at global mappings of stratospheric trace gasses by means of the most sensitive submillimeter receiver ever operated in space. Such sensitivity is ascribed to a Superconductor-Insulator- Superconductor (SIS) mixer, which is operated at 4.5 K in a dedicated cryostat combined with a mechanical cooler. SMILES will observe ozone-depletion-related molecules such as ClO, HCl, HO2, HNO3, BrO and O3 in the frequency bands at 624.32 - 626.32 GHz, and 649.12 - 650.32 GHz. A scanning antenna will cover tangent altitudes from 10 to 60 km in every 53 seconds, while tracing latitudes from 38S to 65N along its orbit. This global coverage makes SMILES a useful tool of observing the low- and mid-latitudinal areas as well as the Arctic peripheral region. The molecular emissions will be detected by two units of acousto-optic spectrometers (AOS), each of which has coverage of 1.2 GHz with a resolution of 1.8 MHz. This high-resolution spectroscopy will allow us to detect weal emission lines attributing to less-abundant species.

  9. Simultaneous measurement of temperature and emissivity of lunar regolith simulant using dual-channel millimeter-wave radiometry

    Energy Technology Data Exchange (ETDEWEB)

    McCloy, J. S.; Sundaram, S. K.; Matyas, J.; Woskov, P. P.

    2011-01-01

    Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments (high temperature, pressure, and corrosive environments). The state-of-the-art dual channel MMW passive radiometer with active interferometric capabilities at 137 GHz described here allows for radiometric measurements of sample temperature and emissivity up to at least 1600 °C with simultaneous measurement of sample surface dynamics. These capabilities have been used to demonstrate dynamic measurement of melting of powders of simulated lunar regolith and static measurement of emissivity of solid samples. The paper presents the theoretical background and basis for the dual-receiver system, describes the hardware in detail, and demonstrates the data analysis. Post-experiment analysis of emissivity versus temperature allows further extraction from the radiometric data of millimeter wave viewing beam coupling factors, which provide corroboratory evidence to the interferometric data of the process dynamics observed. Finally, these results show the promise of the MMW system for extracting quantitative and qualitative process parameters for industrial processes and access to real-time dynamics of materials behavior in extreme environments.

  10. Simultaneous measurement of temperature and emissivity of lunar regolith simulant using dual-channel millimeter-wave radiometry.

    Science.gov (United States)

    McCloy, J S; Sundaram, S K; Matyas, J; Woskov, P P

    2011-05-01

    Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments (high temperature, pressure, and corrosive environments). The state-of-the-art dual channel MMW passive radiometer with active interferometric capabilities at 137 GHz described here allows for radiometric measurements of sample temperature and emissivity up to at least 1600 °C with simultaneous measurement of sample surface dynamics. These capabilities have been used to demonstrate dynamic measurement of melting of powders of simulated lunar regolith and static measurement of emissivity of solid samples. The paper presents the theoretical background and basis for the dual-receiver system, describes the hardware in detail, and demonstrates the data analysis. Post-experiment analysis of emissivity versus temperature allows further extraction from the radiometric data of millimeter wave viewing beam coupling factors, which provide corroboratory evidence to the interferometric data of the process dynamics observed. These results show the promise of the MMW system for extracting quantitative and qualitative process parameters for industrial processes and access to real-time dynamics of materials behavior in extreme environments. PMID:21639528

  11. Lower Hybrid Wave Induced SOL Emissivity Variation at High Density on the Alcator C-Mod Tokamak

    International Nuclear Information System (INIS)

    Lower Hybrid Current Drive (LHCD) in the Alcator C-Mod tokamak provides current profile control for the generation of Advanced Tokamak (AT) plasmas. Non-thermal electron bremsstrahlung emission decreases dramatically at n-bare>1·1020[m-3] for diverted discharges, indicating low current drive efficiency. It is suggested that Scrape-Off-Layer (SOL) collisional absorption of LH waves is the cause for the absence of non-thermal electrons at high density. VUV and visible spectroscopy in the SOL provide direct information on collision excitation processes. Deuterium Balmer-, Lyman- and He-I transition emission measurements were used for initial characterization of SOL electron-neutral collisional absorption. Data from Helium and Deuterium LHCD discharges were characterized by an overall increase in the emissivity as well as an outward radial shift in the emissivity profile with increasing plasma density and applied LHCD power. High-temperature, high-field (Te = 5keV,Bt = 8T) helium discharges at high density display increased non-thermal signatures as well as reduced SOL emissivity. Variations in emissivity due to LHCD were seen in SOL regions not magnetically connected to the LH Launcher, indicating global SOL effects due to LHCD.

  12. Effects of Low-Frequency Biasing on Otoacoustic and Neural Measures Suggest that Stimulus-Frequency Otoacoustic Emissions Originate Near the Peak Region of the Traveling Wave

    OpenAIRE

    Lichtenhan, Jeffery T.

    2011-01-01

    Stimulus-frequency otoacoustic emissions (SFOAEs) have been used to study a variety of topics in cochlear mechanics, although a current topic of debate is where in the cochlea these emissions are generated. One hypothesis is that SFOAE generation is predominately near the peak region of the traveling wave. An opposing hypothesis is that SFOAE generation near the peak region is deemphasized compared to generation in the tail region of the traveling wave. A comparison was made between the effec...

  13. Alfv\\'en Wave Turbulence as a Coronal Heating Mechanism: Simultaneously Predicting the Heating Rate and the Wave-Induced Emission Line Broadening

    CERN Document Server

    Oran, R; van der Holst, B; Sokolov, I V; Gombosi, T I

    2014-01-01

    In the present work, we test the predictions of the AWSoM model, a global extended-MHD model capable of calculating the propagation and turbulent dissipation of Alfv\\'en waves in any magnetic topology, against high resolution spectra of the quiescent off-disk solar corona. Wave dissipation is the only heating mechanism assumed in this model. Combining 3D model results with the CHIANTI atomic database, we were able to create synthetic line-of-sight spectra which include the effects of emission line broadening due to both thermal and wave-related non-thermal motions. To the best of our knowledge this is the first time a global model is used to obtain synthetic non-thermal line broadening. We obtained a steady-state solution driven by a synoptic magnetogram and compared the synthetic spectra with SUMER observations of a quiescent area above the solar west limb extending between 1.04 and 1.34 solar radii at the equator. Both the predicted line widths and the total line fluxes were consistent with the observations...

  14. Wave

    OpenAIRE

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for t...

  15. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  16. Wave excitation in inhomogeneous dielectric media.

    Science.gov (United States)

    Cary, John R; Xiang, Nong

    2007-11-01

    The equation describing the propagation of a mode driven by external currents in an inhomogeneous dielectric is derived from the principle of the conservation of wave energy density and wave momentum density. The wave amplitude in steady state is obtained in terms of a simple spatial integration of the driving current. The contribution from the spatial derivative of the dielectric response is found to be important. The analytical predictions are verified through comparison with deltaf particle-in-cell computations of electron Bernstein wave propagation, thus showing applicability to kinetic systems. PMID:18233709

  17. Characterization of Vertical and Horizontal Wave Features in Dayglow Emissions as Observed from a Low-latitude Station, Hyderabad, INDIA.

    Science.gov (United States)

    Islam Laskar, Fazlul; Pallamraju, Duggirala; Chakrabarti, Supriya; Raghavarao, Ravipati; Vijaya Lakshmi, Thatiparthi; Anji Reddy, M.

    2012-07-01

    Due to the unique geomagnetic field configuration, equatorial upper atmosphere of the earth is affected by various electro-dynamical processes, such as, equatorial electrojet (EEJ), equatorial ionization anomaly (EIA), equatorial spread-F (ESF), equatorial temperature and wind anomaly (ETWA). Each of these processes leave their imprint on both the neutral and ionised components of the upper atmosphere. The plasma dynamics can be investigated by radio probing methods. Investigations on the neutral dynamics, however, are possible mainly through the optical measurements. As these phenomena spread over a large spatial extent, it is extremely important to measure their variability over a large field-of-view. Here, we present the results of the wave characteristics observed over a low latitude location, Hyderabad (Geographic: 17.5° N, 78.5° E; Geomagnetic: 8.6° N, 151.8° E), which were obtained using a high spectral-resolution multi-wavelength echelle-grating spectrograph. This instrument obtains oxygen dayglow emissions at 557.7 nm, 630.0 nm, and 777.4 nm wavelengths over a large field-of-view ( of about 140 degrees) that originate from peak altitudes of around 130 km, 230 km, and 300 km, respectively. Initial results from a total of 52 days of data reveal that the dominant wave periodicities in the intensities of these emissions are different for different emission heights. Significant latitudinal dependency is seen in case of 557.7 nm and 630.0 nm. The latitudinal behavior of the emissions show the influence of both the neutral dynamics and electrodynamics of the equatorial origin. The emission variabilities are compared with the empirical and physics based models to discern the dynamical component in them in order to understand the nature of the vertical coupling of atmospheric regions. These results will be presented in light of the electrodynamic effects on them.

  18. On S.N. Bernstein's derivation of Mendel's Law and 'rediscovery' of the Hardy-Weinberg distribution

    Directory of Open Access Journals (Sweden)

    Alan Stark

    2012-01-01

    Full Text Available Around 1923 the soon-to-be famous Soviet mathematician and probabilist Sergei N. Bernstein started to construct an axiomatic foundation of a theory of heredity. He began from the premise of stationarity (constancy of type proportions from the first generation of offspring. This led him to derive the Mendelian coefficients of heredity. It appears that he had no direct influence on the subsequent development of population genetics. A basic assumption of Bernstein was that parents coupled randomly to produce offspring. This paper shows that a simple model of non-random mating, which nevertheless embodies a feature of the Hardy-Weinberg Law, can produce Mendelian coefficients of heredity while maintaining the population distribution. How W. Johannsen's monograph influenced Bernstein is discussed.

  19. On S.N. Bernstein's derivation of Mendel's Law and 'rediscovery' of the Hardy-Weinberg distribution.

    Science.gov (United States)

    Stark, Alan; Seneta, Eugene

    2012-04-01

    Around 1923 the soon-to-be famous Soviet mathematician and probabilist Sergei N. Bernstein started to construct an axiomatic foundation of a theory of heredity. He began from the premise of stationarity (constancy of type proportions) from the first generation of offspring. This led him to derive the Mendelian coefficients of heredity. It appears that he had no direct influence on the subsequent development of population genetics. A basic assumption of Bernstein was that parents coupled randomly to produce offspring. This paper shows that a simple model of non-random mating, which nevertheless embodies a feature of the Hardy-Weinberg Law, can produce Mendelian coefficients of heredity while maintaining the population distribution. How W. Johannsen's monograph influenced Bernstein is discussed. PMID:22888285

  20. Bernstein diffusions for a class of linear parabolic partial differential equations

    OpenAIRE

    Vuillermot, Pierre-A.; Zambrini, Jean-Claude

    2013-01-01

    In this article we prove the existence of Bernstein processes which we associate in a natural way with a class of non-autonomous linear parabolic initial- and …nal-boundary value problems de…ned in bounded convex subsets of Euclidean space of arbitrary dimension. Under certain conditions regarding their joint endpoint distributions, we also prove that such processes become reversible Markov di¤usions. Furthermore we show that those di¤usions satisfy two Itô equations for some suitably constru...

  1. Transport Implementation of the Bernstein-Vazirani Algorithm with Ion Qubits

    CERN Document Server

    Fallek, Spencer; McMahon, Brian; Maller, Kara; Brown, Kenneth; Amini, Jason

    2016-01-01

    Using trapped ion quantum bits in a scalable microfabricated surface trap, we perform the Bernstein-Vazirani algorithm. Our architecture relies upon ion transport and can readily be expanded to larger systems. The algorithm is demonstrated using two- and three-ion chains. For three ions, an improvement is achieved compared to a classical system using the same number of oracle queries. For two ions and one query, we correctly determine an unknown bit string with probability 97.6(8)%. For three ions, we succeed with probability 80.9(3)%.

  2. PAC-Bayes-Bernstein Inequality for Martingales and its Application to Multiarmed Bandits

    CERN Document Server

    Seldin, Yevgeny; Auer, Peter; Laviolette, François; Shawe-Taylor, John

    2011-01-01

    We combine PAC-Bayesian analysis with a Bernstein-type inequality for martingales to obtain a result that makes it possible to control the concentration of multiple (possibly uncountably many) simultaneously evolving and interdependent martingales. We apply this result to derive a regret bound for the multiarmed bandit problem. Our result forms a basis for integrative simultaneous analysis of exploration-exploitation and model order selection trade-offs. It also opens a way for applying PAC-Bayesian analysis in other fields, where sequentially dependent samples and limited feedback are encountered.

  3. Transfinite diameter of Bernstein sets in

    OpenAIRE

    Bialas-Cież Leokadia; Jedrzejowski Mieczysław

    2002-01-01

    Let be a compact set in satisfying the following generalized Bernstein inequality: for each such that , for each polynomial of degree where is a constant independent of and , is an infinite set of natural numbers that is also independent of and . We give an estimate for the transfinite diameter of the set : For satisfying the usual Bernstein inequality (i.e., ), we prove that

  4. Wave-Particle Interaction Analyzer for the Pitch Angle Scattering of Electrons by Whistler-mode Chorus Emissions

    Science.gov (United States)

    Kitahara, M.; Katoh, Y.

    2015-12-01

    Pitch angle scattering of electrons caused by chorus emissions is one of significant wave-particle interactions in the magnetosphere. A number of previous studies treat the pitch angle scattering as a diffusion of distribution function and calculate diffusion coefficients from observed wave spectra. However, in the diffusion model, we cannot evaluate the nonlinearity of the pitch angle scattering, while recent theoretical works and observation results have pointed out the importance of nonlinear effects. A concept of Wave-Particle Interaction Analysis (WPIA) is proposed by Fukuhara et al. (2009). In the frame of the WPIA, we can directly detect wave-particle interactions by calculating the energy exchange between waves and particles. In the present study, in addition to the method to detect the energy exchange, we propose a method to directly detect the pitch angle scattering of resonant particles by calculating G. The G is defined as the accumulation value of a pitch angular component of the Lorentz force acting on each particle. We apply the proposed method to results of the one-dimensional electron hybrid simulation (Katoh and Omura, 2007a, b). By using the wave and particle data obtained at fixed points assumed in the simulation system, we conduct the pseudo-observation in the simulation. In the result of the analysis, we obtain significant values of G for electrons in the kinetic energy and pitch angle ranges satisfying the cyclotron resonance condition. We compare the result of the analysis of G with the temporal variation of both the pitch angle distributions and the wave spectra. While the pitch angle distribution varies by a few percent through interactions, we obtain the statistically significant G. Furthermore, we compare the G with diffusion coefficient D. While the D showed the broadband diffusive scattering, the G values indicated the narrowband strong scattering. We note that in deriving Fokker-Planck equation and diffusion coefficient D, we use the

  5. Multi Reflection of Lamb Wave Emission in an Acoustic Waveguide Sensor

    Directory of Open Access Journals (Sweden)

    Leonhard Michael Reindl

    2013-02-01

    Full Text Available Recently, an acoustic waveguide sensor based on multiple mode conversion of surface acoustic waves at the solid—liquid interfaces has been introduced for the concentration measurement of binary and ternary mixtures, liquid level sensing, investigation of spatial inhomogenities or bubble detection. In this contribution the sound wave propagation within this acoustic waveguide sensor is visualized by Schlieren imaging for continuous and burst operation the first time. In the acoustic waveguide the antisymmetrical zero order Lamb wave mode is excited by a single phase transducer of 1 MHz on thin glass plates of 1 mm thickness. By contact to the investigated liquid Lamb waves propagating on the first plate emit pressure waves into the adjacent liquid, which excites Lamb waves on the second plate, what again causes pressure waves traveling inside the liquid back to the first plate and so on. The Schlieren images prove this multi reflection within the acoustic waveguide, which confirms former considerations and calculations based on the receiver signal. With this knowledge the sensor concepts with the acoustic waveguide sensor can be interpreted in a better manner.

  6. Multi-Spacecraft Analysis of Plasma Jet Events and Associated Whistler-Wave Emissions using MMS Data

    Science.gov (United States)

    Breuillard, Hugo; Le Contel, Olivier; Retino, Alessandro; Chasapis, Alexandros; Chust, Thomas; Cohen, Ian; Wilder, Frederick; Graham, Daniel; Khotyaintsev, Yuri

    2016-04-01

    Plasma jets aka bursty bulk flows play a crucial role in Earth's plasmasheet dynamics, in particular during substorms where they can sometimes even penetrate down to the geosynchronous orbit. The energy input from the solar wind is partly dissipated in jet fronts(also called dipolarization fronts) in the form of strong whistler waves that can heat and accelerate energetic electrons. The ratio of the energy transported during jets to the substorm energy consumption is still under debate due to instrumental limitations. In May 2015 the Magnetospheric Multiscale (MMS) mission evolves in a string-of-pearls configuration with an average inter-satellite distance of 300 km which allows us to study in detail the microphysics of these phenomena. Thus in this study we employ MMS data to investigate the properties of jet fronts propagating earthward and their associated whistler-mode wave emissions. We show that the spatial dynamics of jet fronts are of the order of the ion gyroradius and whistler-wave dynamics have a temporal scale of a few seconds. We also investigate the energy dissipation associated with such waves and their interaction with energetic electrons in the vicinity of the flow/jet braking region. In addition, we make use of ray tracing simulations to evaluate their propagation properties, as well as their impact on particles in the off-equatorial magnetosphere.

  7. Perturbed black holes in Einstein-dilaton-Gauss-Bonnet gravity: stability, ringdown, and gravitational-wave emission

    CERN Document Server

    Blázquez-Salcedo, Jose Luis; Cardoso, Vitor; Ferrari, Valeria; Gualtieri, Leonardo; Khoo, Fech Scen; Kunz, Jutta; Pani, Paolo

    2016-01-01

    Gravitational waves emitted by distorted black holes---such as those arising from the coalescence of two neutron stars or black holes---carry not only information about the corresponding spacetime but also about the underlying theory of gravity. Although general relativity remains the simplest, most elegant and viable theory of gravitation, there are generic and robust arguments indicating that it is not the ultimate description of the gravitational universe. Here we focus on a particularly appealing extension of general relativity, which corrects Einstein's theory through the addition of terms which are second order in curvature: the topological Gauss-Bonnet invariant coupled to a dilaton. We study gravitational-wave emission from black holes in this theory, and (i) find strong evidence that black holes are linearly (mode) stable against both axial and polar perturbations; (ii) discuss how the quasinormal modes of black holes can be excited during collisions involving black holes, and finally (iii) show that...

  8. Observation of atmospheric composition by Superconducting SubMillimeter-wave Limb Emission Sounder (SMILES) onbord International Space Station

    Science.gov (United States)

    Kasai, Y.; Philippe, B.; Mendrok, J.; Ochiai, S.; Urban, J.; Manabe, T.; Kikuchi, K.; Nishibori, T.; Sano, T.; Moller, J.; Murtagh, D. P.

    2009-12-01

    The Superconducting SubMillimeter-wave Limb Emission The Superconducting SubMillimeter-wave Limb Emission Sounder (SMILES) is the first application of superconductor--insulator--superconductor (SIS) heterodyne detector technology to the investigation of the Earth atmosphere from space. SMILES was designed to be onboard the Japanese Experiment Module (JEM) on the International Space Station (ISS), and is scheduled to be launched on 11 September 2009 by the H-II Transfer Vehicle (HTV). SMILES is a collaboration project of the National Institute of Information and Communications Technology (NICT) and the Japan Aerospace Exploration Agency (JAXA). The performance of this state-of-the-art SIS receiver, with an estimated single side band (SSB) receiver noise temperature of 500 K at 625--650 GHz, provides a large improvement in sensitivity compared to the conventional submillimeter-wave Schottky-diode receivers used by the Sub-Millimetre Radiometer (SMR) onboard the Odin satellite (3000K, single side band, 485--580 GHz, cooled) and the Millimeter-wave Limb Sounder (MLS) onboard Aura (12000K, double side band at 625--650 GHz, uncooled). Since the integration time reduces with the square of the system noise temperature, this performance is roughly equivalent to reducing by a factor of up to 5-10 the integration time needed to reaching the same noise equivalent brightness temperatures. SMILES measurements thus have the potential to provide meaningful information on the global distribution of short-lived radical species, such as ozone, HCl, ClO, HO2, HOCl, CH3CN, BrO, H2O and ice cloud. NICT is operating the L2 research/L3 operational processing chain. In this paper, we introduce the status of SMILES data and its observation performance.

  9. Study of a condition for the mode conversion from purely perpendicular electrostatic waves to electromagnetic waves

    Science.gov (United States)

    Kalaee, Mohammad Javad; Katoh, Yuto

    2016-07-01

    One of the mechanisms for generating electromagnetic plasma waves (Z-mode and LO-mode) is mode conversion from electrostatic waves into electromagnetic waves in inhomogeneous plasma. Herein, we study a condition required for mode conversion of electrostatic waves propagating purely perpendicular to the ambient magnetic field, by numerically solving the full dispersion relation. An approximate model is derived describing the coupling between electrostatic waves (hot plasma Bernstein mode) and Z-mode waves at the upper hybrid frequency. The model is used to study conditions required for mode conversion from electrostatic waves (electrostatic electron cyclotron harmonic waves, including Bernstein mode) into electromagnetic plasma waves (LO-mode). It is shown that for mode conversion to occur in inhomogeneous plasma, the angle between the boundary surface and the magnetic field vector should be within a specific range. The range of the angle depends on the norm of the k vector of waves at the site of mode conversion in the inhomogeneous region. The present study reveals that inhomogeneity alone is not a sufficient condition for mode conversion from electrostatic waves to electromagnetic plasma waves and that the angle between the magnetic field and the density gradient plays an important role in the conversion process.

  10. A study of cooling time reduction of interferometric cryogenic gravitational wave detectors using a high-emissivity coating

    Energy Technology Data Exchange (ETDEWEB)

    Sakakibara, Y.; Yamamoto, K.; Chen, D.; Tokoku, C.; Uchiyama, T.; Ohashi, M.; Kuroda, K. [Institute for Cosmic Ray Research (ICRR), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582 (Japan); Kimura, N.; Suzuki, T.; Koike, S. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2014-01-29

    In interferometric cryogenic gravitational wave detectors, there are plans to cool mirrors and their suspension systems (payloads) in order to reduce thermal noise, that is, one of the fundamental noise sources. Because of the large payload masses (several hundred kg in total) and their thermal isolation, a cooling time of several months is required. Our calculation shows that a high-emissivity coating (e.g. a diamond-like carbon (DLC) coating) can reduce the cooling time effectively by enhancing radiation heat transfer. Here, we have experimentally verified the effect of the DLC coating on the reduction of the cooling time.

  11. A study of cooling time reduction of interferometric cryogenic gravitational wave detectors using a high-emissivity coating

    International Nuclear Information System (INIS)

    In interferometric cryogenic gravitational wave detectors, there are plans to cool mirrors and their suspension systems (payloads) in order to reduce thermal noise, that is, one of the fundamental noise sources. Because of the large payload masses (several hundred kg in total) and their thermal isolation, a cooling time of several months is required. Our calculation shows that a high-emissivity coating (e.g. a diamond-like carbon (DLC) coating) can reduce the cooling time effectively by enhancing radiation heat transfer. Here, we have experimentally verified the effect of the DLC coating on the reduction of the cooling time

  12. Gravitational waves and neutrino emissions from the binary neutron star mergers

    International Nuclear Information System (INIS)

    Coalescence of binary neutron stars is a main target of the ground-based gravitational observatory such as KAGRA and important target for the multimessenger astronomy. If gravitational waves and neutrinos from mergers of binary neutron star, it would be possible to probe the nuclear matter inside neutron stars. In this report, we would like to overview the discovery of the binary neutron star and the research for the gravitational wave and introduce our latest research based on Numerical Relativity. (author)

  13. Nonlinear particle simulation of ion cyclotron waves in toroidal geometry

    Energy Technology Data Exchange (ETDEWEB)

    Kuley, A., E-mail: akuley@uci.edu; Lin, Z. [Department of Physics and Astronomy, University of California Irvine, CA-92697 (United States); Bao, J. [Fusion Simulation Center, Peking University, Beijing (China); Department of Physics and Astronomy, University of California Irvine, CA-92697 (United States); Wei, X. S.; Xiao, Y. [Institute of Fusion Theory and Simulation, Zhejiang University, Hangzhou (China)

    2015-12-10

    Global particle simulation model has been developed in this work to provide a first-principles tool for studying the nonlinear interactions of radio frequency (RF) waves with plasmas in tokamak. In this model, ions are considered as fully kinetic particles using the Vlasov equation and electrons are treated as guiding centers using the drift kinetic equation with realistic electron-to-ion mass ratio. Boris push scheme for the ion motion has been developed in the toroidal geometry using magnetic coordinates and successfully verified for the ion cyclotron and ion Bernstein waves in global gyrokinetic toroidal code (GTC). The nonlinear simulation capability is applied to study the parametric decay instability of a pump wave into an ion Bernstein wave side band and a low frequency ion cyclotron quasi mode.

  14. Extracting the QCD Cutoff Parameter Using the Bernstein Polynomials and the Truncated Moments

    Directory of Open Access Journals (Sweden)

    A. Mirjalili

    2014-01-01

    Full Text Available Since there are not experimental data over the whole range of x-Bjorken variable, that is, 0Bernstein polynomials. As a result, Bernstein averages which are related to different orders of the truncated Mellin moment are obtained. These averaged quantities can be considered as the constructed experimental data. By accessing the sufficient experimental data we can do the fitting more precisely. We do the fitting at leading order and next-to-leading order approximations to extract the QCD cutoff parameter. The results are in good agreement with what is being expected.

  15. Giant nonreciprocal emission of spin waves in Ta/Py bilayers.

    Science.gov (United States)

    Kwon, Jae Hyun; Yoon, Jungbum; Deorani, Praveen; Lee, Jong Min; Sinha, Jaivardhan; Lee, Kyung-Jin; Hayashi, Masamitsu; Yang, Hyunsoo

    2016-07-01

    Spin waves are propagating disturbances in the magnetization of magnetic materials. One of their interesting properties is nonreciprocity, exhibiting that their amplitude depends on the magnetization direction. Nonreciprocity in spin waves is of great interest in both fundamental science and applications because it offers an extra knob to control the flow of waves for the technological fields of logics and switch applications. We show a high nonreciprocity in spin waves from Ta/Py bilayer systems with out-of-plane magnetic fields. The nonreciprocity depends on the thickness of Ta underlayer, which is found to induce an interfacial anisotropy. The origin of observed high nonreciprocity is twofold: different polarities of the in-plane magnetization due to different angles of canted out-of-plane anisotropy and the spin pumping effect at the Ta/Py interface. Our findings provide an opportunity to engineer highly efficient, nonreciprocal spin wave-based applications, such as nonreciprocal microwave devices, magnonic logic gates, and information transports. PMID:27419231

  16. Greenhouse gas emission rate estimates from airborne remote sensing in the short-wave infrared

    OpenAIRE

    Krings, Thomas

    2013-01-01

    The quantification of emissions of the greenhouse gases carbon dioxide (CO2) and methane (CH4) is essential for attributing the roles of anthropogenic activity and natural phenomena in global climate change. The current measurement systems and networks, whilst having improved during the last decades, are deficient in many respects. For example, the emissions from localised and point sources such as fossil fuel exploration sites are not readily assessed. A tool developed to better understand p...

  17. Terahertz Detection of Quantum Cascade Laser Emission by Plasma Waves in Field Effect Transistors

    OpenAIRE

    Teppe, Frederic; Consejo, Christophe; Torres, J; Chenaud, Boris; Solignac, Pierre; Fathololoumi, S; Wasilewski, Z. R.; Zholudev, Maksim; Diakonova, Nina; Coquillat, Dominique; El Fatimy, Abdelouahad; Buzatu, Petre; CHAUBET, Christophe; Knap, Wojciech

    2011-01-01

    We report on the resonant detection of a 3.1 THz radiation produced by a quantum cascade laser using a 250 nm gate length GaAs/AlGaAs field effect transistor at liquid nitrogen temperature. We show that the physical mechanism of the detection is related to the plasma waves excited in the transistor channel. The detection is enhanced by increasing the drain current and driving the transistor into saturation regime. These results clearly show that plasma wave nanometer-size transistors can be u...

  18. Comparison of Aspect Angle Effect on Stimulated Electromagnetic Emissions using HAARP and EISCAT facilities

    Science.gov (United States)

    Fu, H.; Scales, W.; Bernhardt, P. A.; Briczinski, S. J.; Kosch, M. J.; Senior, A.; Rietveld, M. T.; Yeoman, T. K.; Ruohoniemi, J. M.

    2012-12-01

    A high power HF heating transmitter can excite a broad spectrum of Stimulated Electromagnetic Emission (SEE) lines by O-mode and X-mode heating. These emissions can provide useful diagnostics during modification of the ionosphere. The HAARP 3.6MW transmitter beam angle has been confirmed as an important factor for exciting ion acoustic (IA) and electrostatic ion cyclotron waves (EIC) by Magnetized Stimulated Brillouin Scatter (MSBS). The newly observed associated SEE spectral emissions by the MSBS process are considered to originate from cascading processes at the upper hybrid resonance region. These beam angle effects on SEE features have been observed during second electron gyro-harmonic heating experiments. These will be studied and described in much greater detail with a systematic investigation here using two facilities using both the EISCAT facility in Tromso, Norway as well as the HAARP facility. It will be shown that both MSBS emissions and ion Bernstein SEE emissions are observed simultaneously with the pump frequency near the third and second electron gyro harmonic and show important systematic variation with beam angle that can be exploited for important diagnostic purposes. At the EISCAT heating facility, SEE features studied near the third and fourth electron gyro-harmonic with simultaneous electron temperature measurement were observed with strong field aligned irregularities. Importance of the proximity of the pump frequency to the gyro-harmonic on the narrowband SEE spectrum will be compared between both facilities as well.

  19. The Use and Value of Bernstein's Work in Studying (In)Equalities in Undergraduate Social Science Education

    Science.gov (United States)

    McLean, Monica; Abbas, Andrea; Ashwin, Paul

    2013-01-01

    This paper illustrates how critical use of Basil Bernstein's theory illuminates the mechanisms by which university knowledge, curriculum and pedagogy both reproduce and interrupt social inequalities. To this end, empirical examples are selected from the findings of the ESRC-funded project "Pedagogic Quality and Inequality in University First…

  20. "Spectral Implementation" for creating pseudo-pure states and a three-qubit Bernstein-Vazirani's algorithm in NMR

    CERN Document Server

    Peng, X; Fang, X; Feng, M; Liu, M; Gao, K; Peng, Xinhua; Zhu, Xiwen; Fang, Ximing; Feng, Mang; Liu, Maili; Gao, Kelin

    2002-01-01

    Based on ''spectral implementation'' proposed by Madi et al. (J. Chem. Phys. 109, 10603, 1998), we have experimentally realized a pseudo-pure state by the line-selective excitation and a three-qubit Bernstein-Vazirani's algorithm using a carbon-13 analine sample in NMR. The superiority of quantum computation to classical counterpart is well displayed.

  1. Narrow band wave emissions and noise around the plasma frequency in the solar wind,

    Czech Academy of Sciences Publication Activity Database

    Chugunov, Yu. V.; Hayosh, Mykhaylo; Fiala, Vladimír; Souček, Jan; Santolík, Ondřej

    Vol. 2. Potsdam : Europlanet, 2007, ---. [European Planetary Science Congress - EPCS 2007. Potsdam (DE), 19.08.2007-24.08.2007] R&D Projects: GA AV ČR IAA301120601 Institutional research plan: CEZ:AV0Z30420517 Keywords : plasma waves * solar wind * receiving antenna Subject RIV: BL - Plasma and Gas Discharge Physics

  2. Gravitational wave emission by the high braking index pulsar PSR J1640-4631

    CERN Document Server

    de Araujo, José C N; Costa, César A

    2016-01-01

    Recently, a braking index for the pulsar PSR J1640-4631 has been measured. With a braking index of $n = 3.15 \\pm 0.03$, this pulsar has the highest braking index ever measured. As it is well known, a pure magnetic dipole brake yields $n = 3$, whereas a pure gravitational wave brake yields $n = 5$. Therefore, each of these mechanisms alone can not account for the braking index found for PSR J1640-4631. Here we show that such a braking index can be accounted for if the spindown model combines magnetic dipole and gravitational wave brakes. Then, we briefly discuss the detectability of this pulsar by aLIGO and the planned Einstein Telescope. In particular, we show that the amplitude of the gravitational wave that comes from our model is around a factor four lower than the amplitude modeled exclusively by gravitational wave energy loss. Another interesting outcome of our modeling is that we are able to obtain the ellipticity from the braking index and other pulsar parameters.

  3. Recent Observations and Modeling of Narrowband Stimulated Electromagnetic Emissions SEEs at the HAARP Facility

    Science.gov (United States)

    Scales, Wayne; Bernhardt, Paul; McCarrick, Michael; Briczinski, Stanley; Mahmoudian, Alireza; Fu, Haiyang; Ranade Bordikar, Maitrayee; Samimi, Alireza

    There has been significant interest in so-called narrowband Stimulated Electromagnetic Emission SEE over the past several years due to recent discoveries at the High Frequency Active Auroral Research Program HAARP facility near Gakone, Alaska. Narrowband SEE (NSEE) has been defined as spectral features in the SEE spectrum typically within 1 kHz of the transmitter (or pump) frequency. SEE is due to nonlinear processes leading to re-radiation at frequencies other than the pump wave frequency during heating the ionospheric plasma with high power HF radio waves. Although NSEE exhibits a richly complex structure, it has now been shown after a substantial number of observations at HAARP, that NSEE can be grouped into two basic classes. The first are those spectral features, associated with Stimulated Brillouin Scatter SBS, which typically occur when the pump frequency is not close to electron gyro-harmonic frequencies. Typically, these spectral features are within roughly 50 Hz of the pump wave frequency where it is to be noted that the O+ ion gyro-frequency is roughly 50 Hz. The second class of spectral features corresponds to the case when the pump wave frequency is typically within roughly 10 kHz of electron gyro-harmonic frequencies. In this case, spectral features ordered by harmonics of ion gyro-frequencies are typically observed, and termed Stimulated Ion Bernstein Scatter SIBS. There is also important parametric behavior on both classes of NSEE depending on the pump wave parameters including the field strength, antenna beam angle, and electron gyro-harmonic number. This presentation will first provide an overview of the recent NSEE experimental observations at HAARP. Both Stimulated Brillouin Scatter SBS and Stimulated Ion Bernstein Scatter SIBS observations will be discussed as well as their relationship to each other. Possible theoretical formulation in terms of parametric decay instabilities will be provided. Computer simulation model results will be presented

  4. Description of Dispersive Wave Emission and Supercontinuum Generation in Silicon Waveguides Using Split-Step Fourier and Runge-Kutta Integration Methods

    Directory of Open Access Journals (Sweden)

    Xuefeng Li

    2014-01-01

    Full Text Available Based on solving numerically the generalized nonlinear Schrödinger equation describing the propagation of high order femtosecond soliton in silicon waveguide under certain parametric conditions by the split-step Fourier and Runge-Kutta integration methods, dispersive wave emission and supercontinuum generation in silicon waveguides are numerically investigated by propagating femtosecond solitons. The numerical results show that the efficient dispersive wave emission can be generated in silicon waveguide, which plays an important role in the process of the supercontinuum generation with the form of Cherenkov radiation, and it is also shown that the high order low-energy solitons and short waveguides are efficient for the dispersive wave emission.

  5. Limits on gravitational wave emission from selected pulsars using LIGO data

    CERN Document Server

    Abbott, B; Adhikari, R; Ageev, A; Allen, B; Amin, R; Anderson, S B; Anderson, W G; Araya, M; Armandula, H; Ashley, M; Asiri, F; Aufmuth, P; Aulbert, C; Babak, S; Balasubramanian, R; Ballmer, S; Barish, B C; Barker, C; Barker, D; Barnes, M; Barr, B; Barton, M A; Bayer, K; Beausoleil, R; Belczynski, K; Bennett, R; Berukoff, S J; Betzwieser, J; Bhawal, B; Bilenko, I A; Billingsley, G; Black, E; Blackburn, K; Blackburn, L; Bland, B; Bochner, B; Bogue, L; Bork, R; Bose, S; Brady, P R; Braginsky, V B; Brau, J E; Brown, D A; Bullington, A; Bunkowski, A; Buonanno, A; Burgess, R; Busby, D; Butler, W E; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cantley, C A; Cardenas, L; Carter, K; Casey, M M; Castiglione, J; Chandler, A; Chapsky, J; Charlton, P; Chatterji, S; Chelkowski, S; Chen, Y; Chickarmane, V; Chin, D; Christensen, N; Churches, D; Cokelaer, T; Colacino, C; Coldwell, R; Coles, M; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Creighton, T D; Crooks, D R M; Csatorday, P; Cusack, B J; Cutler, C; D'Ambrosio, E; Danzmann, K; Daw, E; De Bra, D; Delker, T; Dergachev, V; DeSalvo, R; Dhurandhar, S V; Di Credico, A; Ding, H; Drever, R W P; Dupuis, R J; Edlund, J A; Ehrens, P; Elliffe, E J; Etzel, T; Evans, M; Evans, T; Fairhurst, S; Fallnich, C; Farnham, D; Fejer, M M; Findley, T; Fine, M; Finn, L S; Franzen, K Y; Freise, A; Frey, R; Fritschel, P; Frolov, V V; Fyffe, M; Ganezer, K S; Garofoli, J; Giaime, J A; Gillespie, A; Goda, K; González, G; Gossler, S; Grandclément, P; Grant, A; Gray, C; Gretarsson, A M; Grimmett, D; Grote, H; Grünewald, S; Günther, M; Gustafson, E; Gustafson, R; Hamilton, W O; Hammond, M; Hanson, J; Hardham, C; Harms, J; Harry, G; Hartunian, A; Heefner, J; Hefetz, Y; Heinzel, G; Heng, I S; Hennessy, M; Hepler, N; Heptonstall, A; Heurs, M; Hewitson, M; Hild, S; Hindman, N; Hoang, P; Hough, J; Hrynevych, M; Hua, W; Ito, M; Itoh, Y; Ivanov, A; Jennrich, O; Johnson, B; Johnson, W W; Johnston, W R; Jones, D I; Jones, L; Jungwirth, D; Kalogera, V; Katsavounidis, E; Kawabe, K; Kawamura, S; Kells, W; Kern, J; Khan, A; Killbourn, S; Killow, C J; Kim, C; King, C; King, P; Klimenko, S; Koranda, S; Kotter, K; Kovalik, Yu; Kozak, D; Krishnan, B; Landry, M; Langdale, J; Lantz, B; Lawrence, R; Lazzarini, A; Lei, M; Leonor, I; Libbrecht, K; Libson, A; Lindquist, P; Liu, S; Logan, J; Lormand, M; Lubinski, M; Luck, H; Lyons, T T; Machenschalk, B; MacInnis, M; Mageswaran, M; Mailand, K; Majid, W; Malec, M; Mann, F; Marin, A; Marka, S; Maros, E; Mason, J; Mason, K; Matherny, O; Matone, L; Mavalvala, N; McCarthy, R; McClelland, D E; McHugh, M; McNabb, J W C; Mendell, G; Mercer, R A; Meshkov, S; Messaritaki, E; Messenger, C; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Miyakawa, O; Miyoki, S; Mohanty, S; Moreno, G; Mossavi, K; Müller, G; Mukherjee, S; Murray, P; Myers, J; Nagano, S; Nash, T; Nayak, R; Newton, G; Nocera, F; Noel, J S; Nutzman, P; Olson, T; O'Reilly, B; Ottaway, D J; Ottewill, A; Ouimette, D A; Overmier, H; Owen, B J; Pan, Y; Papa, M A; Parameshwaraiah, V; Parameswariah, C; Pedraza, M; Penn, S; Pitkin, M; Plissi, M; Prix, R; Quetschke, V; Raab, F; Radkins, H; Rahkola, R; Rakhmanov, M; Rao, S R; Rawlins, K; Ray-Majumder, S; Re, V; Redding, D; Regehr, M W; Regimbau, T; Reid, S; Reilly, K T; Reithmaier, K; Reitze, D H; Richman, S; Riesen, R; Riles, K; Rivera, B; Rizzi, A; Robertson, D I; Robertson, N A; Robison, L; Roddy, S; Rollins, J; Romano, J D; Romie, J; Rong, H; Rose, D; Rotthoff, E; Rowan, S; Rüdiger, A; Russell, P; Ryan, K; Salzman, I; Sandberg, V; Sanders, G H; Sannibale, V; Sathyaprakash, B; Saulson, P R; Savage, R; Sazonov, A; Schilling, R; Schlaufman, K; Schmidt, V; Schnabel, R; Schofield, R; Schutz, B F; Schwinberg, P; Scott, S M; Seader, S E; Searle, A C; Sears, B; Seel, S; Seifert, F; Sengupta, A S; Shapiro, C A; Shawhan, P; Shoemaker, D H; Shu, Q Z; Sibley, A; Siemens, X; Sievers, L; Sigg, D; Sintes, A M; Smith, J R; Smith, M; Smith, M R; Sneddon, P H; Spero, R; Stapfer, G; Steussy, D; Strain, K A; Strom, D; Stuver, A; Summerscales, T; Sumner, M C; Sutton, P J; Sylvestre, J; Takamori, A; Tanner, D B; Tariq, H; Taylor, I; Taylor, R; Thorne, K A; Thorne, K S; Tibbits, M; Tilav, S; Tinto, M; Tokmakov, K V; Torres, C; Torrie, C; Traylor, G; Tyler, W; Ugolini, D W; Ungarelli, C; Vallisneri, M; Van Putten, M H P M; Vass, S; Vecchio, A; Veitch, J; Vorvick, C; Vyachanin, S P; Wallace, L; Walther, H; Ward, H; Ware, B; Watts, K; Webber, D; Weidner, A; Weiland, U; Weinstein, A; Weiss, R; Welling, H; Wen, L; Wen, S; Whelan, J T; Whitcomb, S E; Whiting, B F; Wiley, S; Wilkinson, C; Willems, P A; Williams, P R; Williams, R; Willke, B; Wilson, A; Winjum, B J; Winkler, W; Wise, S; Wiseman, A G; Woan, G; Wooley, R; Worden, J; Wu, W; Yakushin, I; Yamamoto, H; Yoshida, S; Zaleski, K D; Zanolin, M; Zawischa, I; Zhang, L; Zhu, R; Zotov, N P; Zucker, M; Zweizig, J; Krämer, M; Lyne, A G

    2004-01-01

    We place direct upper limits on the strain of the gravitational waves from 28 isolated radio pulsars by a coherent multi-detector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational wave signals. The unprecedented sensitivity of the detectors allow us to set strain upper limits as low as a few times $10^{-24}$. These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than $10^{-5}$ for the four closest pulsars.

  6. Vlasov-Maxwell, self-consistent electromagnetic wave emission simulations of type III solar radio bursts

    CERN Document Server

    Tsiklauri, David

    2010-01-01

    1.5D Vlasov-Maxwell simulations are employed to model electromagnetic emission generation in a fully self-consistent plasma kinetic model for the first time in the solar physics context. The simulations mimic the plasma emission mechanism and Larmor drift instability in a plasma thread that connects the Sun to Earth with the spatial scales compressed appropriately. The effects of spatial density gradients on the generation of electromagnetic radiation are investigated. It is shown that 1.5D inhomogeneous plasma with a uniform background magnetic field directed transverse to the density gradient is aperiodically unstable to Larmor-drift instability. The latter results in a novel effect of generation of electromagnetic emission at plasma frequency. When density gradient is removed (i.e. when plasma becomes stable to Larmor-drift instability) and a $low$ density, super-thermal, hot beam is injected along the domain, in the direction perpendicular to the magnetic field, plasma emission mechanism generates non-esc...

  7. Atmospheric Physics and Earth Observations: Waves in the OH Emissive Layer.

    Science.gov (United States)

    Hersé, M

    1984-07-13

    An instrument designed to take pictures of infrared spatial structures from space was flown on Spacelab 1. An image intensifier was used to give enough sensitivity and images were recorded on photographic film. The instrument worked perfectly and 1771 pictures were obtained during the night on 27 orbits (one picture every 16 seconds). Image processing of the data will yield information about the extension of large-scale structures and the relation between medium-scale structures and gravity waves. PMID:17837929

  8. Greenhouse gas emission rate estimates from airborne remote sensing in the short-wave infrared

    International Nuclear Information System (INIS)

    The quantification of emissions of the greenhouse gases carbon dioxide (CO2) and methane (CH4) is essential for attributing the roles of anthropogenic activity and natural phenomena in global climate change. The current measurement systems and networks, whilst having improved during the last decades, are deficient in many respects. For example, the emissions from localised and point sources such as fossil fuel exploration sites are not readily assessed. A tool developed to better understand point sources of CO2 and CH4 is the optical remote sensing instrument MAMAP, operated from aircraft. With a ground scene size of the order of 50m and a relative accuracy of the column-averaged dry air mole fractions of about 0.3% for XCO2 and less than 0.4% for XCH4, MAMAP can make a significant contribution in this respect. Detailed sensitivity studies showed that the modified WFM-DOAS retrieval algorithm used for MAMAP has an approximate accuracy of about 0.24% for XCH4 and XCO2 in typical atmospheric conditions. At the example of CO2 plumes from two different power plants and CH4 plumes from coal mine ventilation shafts, two inversion approaches to obtain emission rates were developed and tested. One is based on an optimal estimation scheme to fit Gaussian plume models from multiple sources to the data and the other is based on a simple Gaussian integral method. Compared to CO2 emission estimates as reported by the power plants' operator within the framework of emission databases (24 and 13 MtCO2 yr-1), the results of the individual inversion techniques were within ±10% with uncertainties of ±20-30% mainly due to insufficient wind information and non-stationary atmospheric conditions. Measurements at the coal mine included on-site wind observations by an aircraft turbulence probe that could be utilised to calibrate the wind model. In this case, the inversion results have a bias of less than 1% compared to the reported CH4 emissions (50 ktCO2 yr-1) with an uncertainty

  9. Non Axisymmetric Three-Dimensional Magnetic Bernstein-Greene-Kruskal (BGK) Modes

    Science.gov (United States)

    Ng, Chung-Sang

    2013-10-01

    The theory of three-dimensional (3D) magnetic Magnetic Bernstein-Greene-Kruskal (BGK) modes has been generalized to the non axisymmetric case. While the shape of the electrostatic structure is usually elongated along the direction of the strong large-scale magnetic field, a limiting case with the elongated direction along one of the perpendicular direction is also possible. Essentially this makes the solution 2D with the magnetic field on the 2D plane. Note that such 2D BGK modes are very different from those described by another theory, of which the magnetic field is perpendicular to the 2D plane. This theory might explain 2D BGK modes observed in some numerical simulations. This work is supported by a National Science Foundation grant PHY-1004357 and by the National Science Foundation of China NSFC under Grant No. 41128004.

  10. MM-wave emission by magnetized plasma during sub-relativistic electron beam relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, I. A., E-mail: Ivanov@inp.nsk.su; Arzhannikov, A. V.; Burmasov, V. S.; Popov, S. S.; Postupaev, V. V.; Sklyarov, V. F.; Vyacheslavov, L. N. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090 (Russian Federation); Burdakov, A. V.; Sorokina, N. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20 Karl Marx Avenue, Novosibirsk 630092 (Russian Federation); Gavrilenko, D. E.; Kasatov, A. A.; Kandaurov, I. V.; Mekler, K. I.; Rovenskikh, A. F.; Trunev, Yu. A. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Kurkuchekov, V. V.; Kuznetsov, S. A. [Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090 (Russian Federation); Polosatkin, S. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2 Pirogova Street, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20 Karl Marx Avenue, Novosibirsk 630092 (Russian Federation)

    2015-12-15

    There are described electromagnetic spectra of radiation emitted by magnetized plasma during sub-relativistic electron beam in a double plasma frequency band. Experimental studies were performed at the multiple-mirror trap GOL-3. The electron beam had the following parameters: 70–110 keV for the electron energy, 1–10 MW for the beam power and 30–300 μs for its duration. The spectrum was measured in 75–230 GHz frequency band. The frequency of the emission follows variations in electron plasma density and magnetic field strength. The specific emission power on the length of the plasma column is estimated on the level 0.75 kW/cm.

  11. The electric field effect and electromagnetic wave emission in intrinsic Josephson junctions

    Science.gov (United States)

    Koyama, T.

    2013-04-01

    We formulate a theory for the electric field effect in intrinsic Josephson junctions (IJJs). The coupled dynamical equations for the phase differences are derived in the presence of both a bias current and an applied electric field on the basis of the capacitively-coupled IJJ model. It is shown that the current-voltage characteristics of the IJJs sensitively depend on the applied electric field. The dipole emission originating from the electric field effect is also predicted.

  12. Metallurgical flow recognition by random signal analysis of stress wave emissions

    International Nuclear Information System (INIS)

    The present study involves detailed random signal analysis of individual 'bursts' of emission with objective of 'reading' their frequency spectra to identify specific metallurgical mechanisms. Mild steel unnotched testpieces were used in the early stages of development of this research. From a fracture mechanics point of view this research could lead to a powerful nondestructive testing device allowing identification of interior, instead of only surface, deformation mechanisms. (author)

  13. Measurements of the millimeter-wave spectrum of interstellar dust emission

    Science.gov (United States)

    Fischer, M. L.; Clapp, A.; Devlin, M.; Gundersen, J. O.; Lange, A. E.; Lubin, P. M.; Meinhold, P. R.; Richards, P. L.; Smoot, G. F.

    1995-01-01

    We report measurements of the differential brightness of interstellar dust emission near the Galactic plane and at high Galactic latitudes. The data were obtained as part of a program to measure anisotropy in the cosmic microwave background (CMB). The measurements were made with a 0.5 deg beam size and a 1.3 deg sinusoidal chop, in broad bands (Delta nu/nu approximately 0.3) centered near frequencies of 6, 9, and 12 cm(exp -1). A measurement made toward the Galactic plane, at longitude 1 = 23.7 deg, is compared with the contrast observed in the 100 micrometers IRAS data. Assuming the dust emission has a brightness I(sub nu) proportional to nu(sup n)B(sub nu)(T(sub d)), where B(sub nu) is the Planck function, a best fit yields n = 1.6 +/- 0.4, T(sub d) = 24 +/- 5 K. In a region near the star mu Pegasi (mu PEG l = 91 deg, b = -31 deg), the comparison of our data with the 100 micrometers IRAS data yields n = 1.4 +/- 0.4, and T(sub d) = 18 +/- 3 K. In a second region near the star gamma Ursa Minoris (GUM l = 108 deg, b = 41 deg), an upper limit is placed on contrast in dust emission. This upper limit is consistent with spectrum measured at mu PEG and the IRAS 100 micrometer emission contrast at GUM, which is approximately 8 times lower than mu PEG.

  14. Wave-particle interactions in the equatorial source region of whistler-mode emissions

    Czech Academy of Sciences Publication Activity Database

    Santolík, Ondřej; Gurnett, D. A.; Pickett, J. S.; Grimald, S.; Décréau, P. M. E.; Parrot, M.; Cornilleau-Wehrlin, N.; El-Lemdani Mazouz, F.; Schriver, D.; Meredith, N. P.; Fazakerley, A.

    2010-01-01

    Roč. 115, - (2010), A00F16/1-A00F16/13. ISSN 0148-0227 R&D Projects: GA MŠk(CZ) ME10001; GA ČR GA205/09/1253 Grant ostatní: MŠMT(CZ) MSM0021620860; GA MŠk(CZ) ME 842 Institutional research plan: CEZ:AV0Z30420517 Keywords : wave -particle interactions * equatorial region * Cluster spacecraft Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.303, year: 2010

  15. Afterglow emission from pair-loaded blast waves in gamma-ray bursts

    OpenAIRE

    Beloborodov, Andrei M.

    2005-01-01

    The MeV radiation front of gamma-ray bursts creates copious e+- pairs as it propagates through an ambient medium. The created pairs enrich the leptonic component of the medium by a large factor at distances R < R_load ~ 10^{16} cm from the burst center. The following blast wave sweeps up the pair-rich medium and then emits the observed afterglow radiation. We find that the afterglow has a "memory" of e+- loading outside R_load. The e+- pairs remain in the swept-up material and slowly cool dow...

  16. Greenhouse gas emission rate estimates from airborne remote sensing in the short-wave infrared

    Energy Technology Data Exchange (ETDEWEB)

    Krings, Thomas

    2013-01-30

    The quantification of emissions of the greenhouse gases carbon dioxide (CO{sub 2}) and methane (CH{sub 4}) is essential for attributing the roles of anthropogenic activity and natural phenomena in global climate change. The current measurement systems and networks, whilst having improved during the last decades, are deficient in many respects. For example, the emissions from localised and point sources such as fossil fuel exploration sites are not readily assessed. A tool developed to better understand point sources of CO{sub 2} and CH{sub 4} is the optical remote sensing instrument MAMAP, operated from aircraft. With a ground scene size of the order of 50m and a relative accuracy of the column-averaged dry air mole fractions of about 0.3% for XCO{sub 2} and less than 0.4% for XCH{sub 4}, MAMAP can make a significant contribution in this respect. Detailed sensitivity studies showed that the modified WFM-DOAS retrieval algorithm used for MAMAP has an approximate accuracy of about 0.24% for XCH{sub 4} and XCO{sub 2} in typical atmospheric conditions. At the example of CO{sub 2} plumes from two different power plants and CH{sub 4} plumes from coal mine ventilation shafts, two inversion approaches to obtain emission rates were developed and tested. One is based on an optimal estimation scheme to fit Gaussian plume models from multiple sources to the data and the other is based on a simple Gaussian integral method. Compared to CO{sub 2} emission estimates as reported by the power plants' operator within the framework of emission databases (24 and 13 MtCO{sub 2} yr{sup -1}), the results of the individual inversion techniques were within ±10% with uncertainties of ±20-30% mainly due to insufficient wind information and non-stationary atmospheric conditions. Measurements at the coal mine included on-site wind observations by an aircraft turbulence probe that could be utilised to calibrate the wind model. In this case, the inversion results have a bias of less than 1

  17. Regular and chaotic dynamics of non-spherical bodies. Zeldovich's pancakes and emission of very long gravitational waves

    Science.gov (United States)

    Bisnovatyi-Kogan, G. S.; Tsupko, O. Yu.

    2015-10-01

    > In this paper we review a recently developed approximate method for investigation of dynamics of compressible ellipsoidal figures. Collapse and subsequent behaviour are described by a system of ordinary differential equations for time evolution of semi-axes of a uniformly rotating, three-axis, uniform-density ellipsoid. First, we apply this approach to investigate dynamic stability of non-spherical bodies. We solve the equations that describe, in a simplified way, the Newtonian dynamics of a self-gravitating non-rotating spheroidal body. We find that, after loss of stability, a contraction to a singularity occurs only in a pure spherical collapse, and deviations from spherical symmetry prevent the contraction to the singularity through a stabilizing action of nonlinear non-spherical oscillations. The development of instability leads to the formation of a regularly or chaotically oscillating body, in which dynamical motion prevents the formation of the singularity. We find regions of chaotic and regular pulsations by constructing a Poincaré diagram. A real collapse occurs after damping of the oscillations because of energy losses, shock wave formation or viscosity. We use our approach to investigate approximately the first stages of collapse during the large scale structure formation. The theory of this process started from ideas of Ya. B. Zeldovich, concerning the formation of strongly non-spherical structures during nonlinear stages of the development of gravitational instability, known as `Zeldovich's pancakes'. In this paper the collapse of non-collisional dark matter and the formation of pancake structures are investigated approximately. Violent relaxation, mass and angular momentum losses are taken into account phenomenologically. We estimate an emission of very long gravitational waves during the collapse, and discuss the possibility of gravitational lensing and polarization of the cosmic microwave background by these waves.

  18. Gravitational waves, neutrino emissions, and effects of hyperons in binary neutron star mergers

    CERN Document Server

    Kiuchi, Kenta; Kyutoku, Koutarou; Shibata, Masaru

    2012-01-01

    Numerical simulations for the merger of binary neutron stars are performed in full general relativity incorporating both nucleonic and hyperonic finite-temperature equations of state (EOS) and neutrino cooling. It is found that for the nucleonic and hyperonic EOS, a hyper massive neutron star (HMNS) with a long lifetime $(t_{\\rm life}\\gtrsim 10 {\\rm ms})$ is the outcome for the total mass $\\approx 2.7 M_\\odot$. For the total mass $\\approx 3 M_\\odot$, a long-lived (short-lived with $t_{\\rm life}\\approx 3 {\\rm ms}$) HMNS is the outcome for the nucleonic (hyperonic) EOS. It is shown that the typical total neutrino luminosity of the HMNS is $\\sim 3$ -- $6 \\times 10^{53} {\\rm erg /s}$ and the effective amplitude of gravitational waves from the HMNS is 1 -- $4\\times 10^{-22}$ at $f\\approx 2$ -- $3.2 {\\rm kHz}$ for a source of distance of 100 Mpc. During the HMNS phase, characteristic frequencies of gravitational waves shift to a higher frequency for the hyperonic EOS in contrast to the nucleonic EOS in which they r...

  19. Passive wireless surface acoustic wave sensors for monitoring sequestration sites CO2 emission

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yizhong [Univ. of Pittsburgh, PA (United States); Chyu, Minking [Univ. of Pittsburgh, PA (United States); Wang, Qing-Ming [Univ. of Pittsburgh, PA (United States)

    2013-02-14

    University of Pittsburgh’s Transducer lab has teamed with the U.S. Department of Energy’s National Energy Technology Laboratory (DOE NETL) to conduct a comprehensive study to develop/evaluate low-cost, efficient CO2 measuring technologies for geological sequestration sites leakage monitoring. A passive wireless CO2 sensing system based on surface acoustic wave technology and carbon nanotube nanocomposite was developed. Surface acoustic wave device was studied to determine the optimum parameters. Delay line structure was adopted as basic sensor structure. CNT polymer nanocomposite was fabricated and tested under different temperature and strain condition for natural environment impact evaluation. Nanocomposite resistance increased for 5 times under pure strain, while the temperature dependence of resistance for CNT solely was -1375ppm/°C. The overall effect of temperature on nanocomposite resistance was -1000ppm/°C. The gas response of the nanocomposite was about 10% resistance increase under pure CO2 . The sensor frequency change was around 300ppm for pure CO2 . With paralyne packaging, the sensor frequency change from relative humidity of 0% to 100% at room temperature decreased from over 1000ppm to less than 100ppm. The lowest detection limit of the sensor is 1% gas concentration, with 36ppm frequency change. Wireless module was tested and showed over one foot transmission distance at preferred parallel orientation.

  20. Global ion cyclotron waves in a perpendicularly stratified, one-dimensional warm plasma

    International Nuclear Information System (INIS)

    The sixth-order wave equation which results from a finite temperature expansion of the Vlasov equation is solved globally in a perpendicularly stratified, one-dimensional slab plasma. The diamagnetic drift and associated anisotropy are included in the unperturbed distribution function to ensure a self-adjoint system. All x-dependence in the plasma pressure and magnetic field is retained along with the electric field parallel to vector B. Thus, Landau damping of the ion Bernstein wave is included as well. Because the wave equation is solved implicitly as a two-point boundary value problem, the evanescent short-wavelength Bernstein waves do not grow exponentially as in shooting methods. Solutions to the complete sixth-order partial differential equation are compared to those from an approximate second-order equation based on local dispersion theory. Strong variations occur in the absorption and in the structure of the wave fields as resonance topology is varied

  1. Theory and observations of electrostatic ion waves in the cold Io torus

    Science.gov (United States)

    Barbosa, D. D.; Kurth, W. S.

    1990-01-01

    A study of the ELF plasma wave environment of the cold Io torus in Jupiter's magnetosphere is made. Voyager 1 data are presented which show three distinct types of electrostatic ion waves occurring there: the Buchsbaum ion-ion mode just below the proton cyclotron frequency f(cp), hydrogen Bernstein modes at (n + 1/2) f(cp), and lower hybrid waves near f(LHR). The presence of these waves at their characteristic frequencies is consistent with a predominantly heavy ion plasma composed of singly ionized sulfur and oxygen ions along with a small admixture of protons. The hydrogen Bernstein modes are tightly confined to the magnetic equator, occurring within + or - 4 deg of it, while the Buchsbaum mode is localized to the dense heavy ion plasma of the cold torus near the centrifugal equator. A general theory for excitation of the waves based on the ion pickup process is developed.

  2. Triple functional DNA-protein conjugates: Signal probes for Pb(2+) using evanescent wave-induced emission.

    Science.gov (United States)

    Wang, Ruoyu; Zhou, Xiaohong; Shi, Hanchang

    2015-12-15

    We describe here a Pb(2+)-dependent DNAzyme-based evanescent wave-induced emission (EWIE) biosensing platform using triple functional DNA-protein conjugates as signal probes for Pb(2+) detection. Upon reaction with Pb(2+), the substrate strand is cleaved, releasing an invasion fragment, which is then hybridized with the complementary DNA strand immobilized on magnetic beads, while dissociating of the original hybridized signal probes. The signal probes, consisting of a streptavidin moiety and a Cy5.5 labeled DNA moiety, act simultaneously as signal conversion, signal recognition and signal report elements. Detection of the signal probes is accomplished by first adsorbing to the desthiobiotin-modified optical fiber, followed by fluorescence emission induced by an evanescent field. A linear calibration was obtained from 20 nM to 800 nM with a detection limit of 1 nM. The optical fiber system is robust enough for 250 sensing cycles and can be stored at room temperature over one month. These results demonstrate that application of DNA-streptavidin conjugates has been extended to DNAzyme-based biosensors, maintaining activity, specificity, regeneration and long-term storage ability. PMID:26120813

  3. Discovery of Millimeter-Wave Excess Emission in Radio-Quiet Active Galactic Nuclei

    OpenAIRE

    Behar, Ehud; Baldi, Ranieri D.; Laor, Ari; Horesh, Assaf; Stevens, Jamie; Tzioumis, Tasso

    2015-01-01

    The physical origin of radio emission in Radio Quiet Active Galactic Nuclei (RQ AGN) remains unclear, whether it is a downscaled version of the relativistic jets typical of Radio Loud (RL) AGN, or whether it originates from the accretion disk. The correlation between 5 GHz and X-ray luminosities of RQ AGN, which follows $L_R = 10^{-5}L_X$ observed also in stellar coronae, suggests an association of both X-ray and radio sources with the accretion disk corona. Observing RQ AGN at higher (mm-wav...

  4. An Analytical Solution for Acoustic Emission Source Location for Known P Wave Velocity System

    Directory of Open Access Journals (Sweden)

    Longjun Dong

    2014-01-01

    Full Text Available This paper presents a three-dimensional analytical solution for acoustic emission source location using time difference of arrival (TDOA measurements from N receivers, N⩾5. The nonlinear location equations for TDOA are simplified to linear equations, and the direct analytical solution is obtained by solving the linear equations. There are not calculations of square roots in solution equations. The method solved the problems of the existence and multiplicity of solutions induced by the calculations of square roots in existed close-form methods. Simulations are included to study the algorithms' performance and compare with the existing technique.

  5. New Trends in Energy Harvesting from Earth Long-Wave Infrared Emission

    Directory of Open Access Journals (Sweden)

    Luciano Mescia

    2014-01-01

    Full Text Available A review, even if not exhaustive, on the current technologies able to harvest energy from Earth’s thermal infrared emission is reported. In particular, we discuss the role of the rectenna system on transforming the thermal energy, provided by the Sun and reemitted from the Earth, in electricity. The operating principles, efficiency limits, system design considerations, and possible technological implementations are illustrated. Peculiar features of THz and IR antennas, such as physical properties and antenna parameters, are provided. Moreover, some design guidelines for isolated antenna, rectifying diode, and antenna coupled to rectifying diode are exploited.

  6. Molecular Line Emission from Multifluid Shock Waves. I. Numerical Methods and Benchmark Tests

    CERN Document Server

    Ciolek, Glenn E

    2013-01-01

    We describe a numerical scheme for studying time-dependent, multifluid, magnetohydrodynamic shock waves in weakly ionized interstellar clouds and cores. Shocks are modeled as propagating perpendicular to the magnetic field and consist of a neutral molecular fluid plus a fluid of ions and electrons. The scheme is based on operator splitting, wherein time integration of the governing equations is split into separate parts. In one part independent homogeneous Riemann problems for the two fluids are solved using Godunov's method. In the other equations containing the source terms for transfer of mass, momentum, and energy between the fluids are integrated using standard numerical techniques. We show that, for the frequent case where the thermal pressures of the ions and electrons are << magnetic pressure, the Riemann problems for the neutral and ion-electron fluids have a similar mathematical structure which facilitates numerical coding. Implementation of the scheme is discussed and several benchmark tests ...

  7. Effects on ion cyclotron emission of the orbit topology changes from the wave-particle interactions

    International Nuclear Information System (INIS)

    It is known that non-relaxed distribution functions can give rise to excitation of magnetosonic waves by ion cyclotron interactions when the distribution function increases with respect to the perpendicular velocity. We have found that in a toroidal plasma also collisional relaxed distribution functions of central peaked high-energy ions can destabilise magnetosonic eigenmodes by ion cyclotron interactions, due to the change in localisation of the orbits establishing inverted distribution functions with respect to energy along the characteristics describing the cyclotron interactions. This can take place by interactions with barely co-passing and marginally trapped high-energy ions at the plasma boundary. The interactions are enhanced by tangential interactions, which can also prevent the interactions to reach the stable part of the characteristics where they interact with more deeply trapped orbits. (author)

  8. Effects on Ion Cyclotron Emission of the Orbit Topology Changes from the Wave-Particle Interactions

    International Nuclear Information System (INIS)

    It is known that non-relaxed distribution functions can give rise to excitation of magnetosonic waves by ion cyclotron interactions when the distribution function increases with respect to the perpendicular velocity. We have found that in a toroidal plasma also collisional relaxed distribution functions of central peaked high-energy ions can destabilise magnetosonic eigenmodes by ion cyclotron interactions, due to the change in localisation of the orbits establishing inverted distribution functions with respect to energy along the characteristics describing the cyclotron interactions. This can take place by interactions with barely co-passing and marginally trapped high-energy ions at the plasma boundary. The interactions are enhanced by tangential interactions, which can also prevent the interactions to reach the stable part of the characteristics where they interact with more deeply trapped orbits. (author)

  9. Human brain wave activity during exposure to radiofrequency field emissions from mobile phones

    International Nuclear Information System (INIS)

    The aim of this study was to determine whether there is an effect of mobile phone electromagnetic field emissions on the human electroencephalograph (EEG). EEG recordings from ten awake subjects were taken during exposure to radiofrequency (RF) emissions from a mobile phone positioned behind the head. Two experimental trials were conducted. In the first trial, RF exposures were generated by a GSM mobile phone with the speaker disabled and configured to transmit at full-radiated power. During the second trial, exposures were generated by a non-modified GSM mobile phone in active standby mode. For each trial, subjects were exposed in five minute intervals to a randomized, interrupted sequence of five active and five sham exposures. The experiment was conducted under single-blind conditions. The average EEG band power in active exposure recordings was compared to corresponding sham recordings. Statistical tests indicated significant difference in the full-power mode trial within the EEG alpha (8-13 Hz) and beta (13-32 Hz) bands. A subsequent statistical analysis of median spectral power in discrete EEG rhythms revealed significant differences in 7 of the 32 distinct frequencies overall. In conclusion, the results of this study lend support to EEG effects from mobile phones activated in talk-mode. Copyright (2003) Australasian College of Physical Scientists and Engineers in Medicine

  10. MOLECULAR LINE EMISSION FROM MULTIFLUID SHOCK WAVES. I. NUMERICAL METHODS AND BENCHMARK TESTS

    International Nuclear Information System (INIS)

    We describe a numerical scheme for studying time-dependent, multifluid, magnetohydrodynamic shock waves in weakly ionized interstellar clouds and cores. Shocks are modeled as propagating perpendicular to the magnetic field and consist of a neutral molecular fluid plus a fluid of ions and electrons. The scheme is based on operator splitting, wherein time integration of the governing equations is split into separate parts. In one part, independent homogeneous Riemann problems for the two fluids are solved using Godunov's method. In the other, equations containing the source terms for transfer of mass, momentum, and energy between the fluids are integrated using standard numerical techniques. We show that, for the frequent case where the thermal pressures of the ions and electrons are << magnetic pressure, the Riemann problems for the neutral and ion-electron fluids have a similar mathematical structure which facilitates numerical coding. Implementation of the scheme is discussed and several benchmark tests confirming its accuracy are presented, including (1) MHD wave packets ranging over orders of magnitude in length- and timescales, (2) early evolution of multifluid shocks caused by two colliding clouds, and (3) a multifluid shock with mass transfer between the fluids by cosmic-ray ionization and ion-electron recombination, demonstrating the effect of ion mass loading on magnetic precursors of MHD shocks. An exact solution to an MHD Riemann problem forming the basis for an approximate numerical solver used in the homogeneous part of our scheme is presented, along with derivations of the analytic benchmark solutions and tests showing the convergence of the numerical algorithm.

  11. MOLECULAR LINE EMISSION FROM MULTIFLUID SHOCK WAVES. I. NUMERICAL METHODS AND BENCHMARK TESTS

    Energy Technology Data Exchange (ETDEWEB)

    Ciolek, Glenn E.; Roberge, Wayne G., E-mail: cioleg@rpi.edu, E-mail: roberw@rpi.edu [New York Center for Astrobiology (United States); Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States)

    2013-05-01

    We describe a numerical scheme for studying time-dependent, multifluid, magnetohydrodynamic shock waves in weakly ionized interstellar clouds and cores. Shocks are modeled as propagating perpendicular to the magnetic field and consist of a neutral molecular fluid plus a fluid of ions and electrons. The scheme is based on operator splitting, wherein time integration of the governing equations is split into separate parts. In one part, independent homogeneous Riemann problems for the two fluids are solved using Godunov's method. In the other, equations containing the source terms for transfer of mass, momentum, and energy between the fluids are integrated using standard numerical techniques. We show that, for the frequent case where the thermal pressures of the ions and electrons are << magnetic pressure, the Riemann problems for the neutral and ion-electron fluids have a similar mathematical structure which facilitates numerical coding. Implementation of the scheme is discussed and several benchmark tests confirming its accuracy are presented, including (1) MHD wave packets ranging over orders of magnitude in length- and timescales, (2) early evolution of multifluid shocks caused by two colliding clouds, and (3) a multifluid shock with mass transfer between the fluids by cosmic-ray ionization and ion-electron recombination, demonstrating the effect of ion mass loading on magnetic precursors of MHD shocks. An exact solution to an MHD Riemann problem forming the basis for an approximate numerical solver used in the homogeneous part of our scheme is presented, along with derivations of the analytic benchmark solutions and tests showing the convergence of the numerical algorithm.

  12. Molecular Line Emission from Multifluid Shock Waves. I. Numerical Methods and Benchmark Tests

    Science.gov (United States)

    Ciolek, Glenn E.; Roberge, Wayne G.

    2013-05-01

    We describe a numerical scheme for studying time-dependent, multifluid, magnetohydrodynamic shock waves in weakly ionized interstellar clouds and cores. Shocks are modeled as propagating perpendicular to the magnetic field and consist of a neutral molecular fluid plus a fluid of ions and electrons. The scheme is based on operator splitting, wherein time integration of the governing equations is split into separate parts. In one part, independent homogeneous Riemann problems for the two fluids are solved using Godunov's method. In the other, equations containing the source terms for transfer of mass, momentum, and energy between the fluids are integrated using standard numerical techniques. We show that, for the frequent case where the thermal pressures of the ions and electrons are Lt magnetic pressure, the Riemann problems for the neutral and ion-electron fluids have a similar mathematical structure which facilitates numerical coding. Implementation of the scheme is discussed and several benchmark tests confirming its accuracy are presented, including (1) MHD wave packets ranging over orders of magnitude in length- and timescales, (2) early evolution of multifluid shocks caused by two colliding clouds, and (3) a multifluid shock with mass transfer between the fluids by cosmic-ray ionization and ion-electron recombination, demonstrating the effect of ion mass loading on magnetic precursors of MHD shocks. An exact solution to an MHD Riemann problem forming the basis for an approximate numerical solver used in the homogeneous part of our scheme is presented, along with derivations of the analytic benchmark solutions and tests showing the convergence of the numerical algorithm.

  13. Ion wave excitation for the study of wave-induced transport

    International Nuclear Information System (INIS)

    A general program to study wave-particle interactions and wave-induced transport in a low temperature, low density, collisionless plasma has led to the application of an assortment of ion wave launching schemes. This wave launching techniques include the use of: capacitively coupled rings at the plasma periphery, inductive coils, grids immersed in the plasma, and ion wave excitation by modulation of microwaves (double resonance). The generated ion waves are either ion acoustic, the forward and backward (neutralized ion Bernstein) branches of electrostatic ion cyclotron, and/or ballistic modes. Our earlier studies have addressed the ion interaction with a single monochromatic wave, such as ion acceleration by intrinsic stochasticity induced by interaction with an ion Bernstein mode, and ion coordinate space diffusion constrained by conservation of integrals of the motion in this deterministic system. In the case of linear ion acoustic wave-particle interaction, an experimental test ion approach has yielded direct evidence of phase space orbit perturbations for ions resonant with the wave phase velocity, demonstrating on the kinetic level the essence of ion Landau damping. We are now turning our attention to the problem of stochastic interaction with two ion cyclotron modes. A detailed knowledge of the waves excited by the antenna will allow a selection of mode phase velocities such that the separation of wave-particle resonances can be controlled. In this way, the wave field amplitudes necessary for reaching the stochasticity threshold can be reduced, in comparison to the situation with one wave. This paper reviews the wave dispersion characteristics compiled during the aforementioned wave-particle interaction studies. It will be seen that the plasma dispersion relation universally determines the wave response, quite independent of the antenna configuration. (author) 9 refs., 4 figs

  14. The Bernstein Operational Matrices for Solving the Fractional Quadratic Riccati Differential Equations with the Riemann-Liouville Derivative

    OpenAIRE

    Dumitru Baleanu; Mohsen Alipour; Hossein Jafari

    2013-01-01

    We obtain the approximate analytical solution for the fractional quadratic Riccati differential equation with the Riemann-Liouville derivative by using the Bernstein polynomials (BPs) operational matrices. In this method, we use the operational matrix for fractional integration in the Riemann-Liouville sense. Then by using this matrix and operational matrix of product, we reduce the problem to a system of algebraic equations that can be solved easily. The efficiency and accuracy of the propos...

  15. Observation capability of Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) from International Space Station

    Science.gov (United States)

    Kasai, Yasuko; Baron, Philippe; Mendrok, Jana; Tanaka, Takahiro; Urban, Joachim; Kita, Kazuyuki; Sato, Ryota; Murtah, Donal; Suzuki, Makoto; Shiotani, Masato

    2010-05-01

    A new generation of super-sensitive submillimeter-wave receivers, employing SIS (Superconductor-Insulator- Superconductor) technology, will provide new opportunities for precise remote sensing observation of minor constituents in the atmosphere. SMILES had been launched at 11/09/2009, and installed on the Japanese Experiment Module (JEM) in the International Space Station (ISS). SMILES is a collaboration project between NICT and JAXA. Mission objectives of SMILES are: i) Space demonstration of super-sensitive SIS mixer and 4-K mechanical cooler technology ii) Super-sensitive global observation of atmospheric minor constituents JEM/SMILES observes the atmospheric species such as O3, H35Cl, H37Cl, ClO, HO2, BrO, HOCl, HOBr, HNO3, CH3CN, Ozone isotope species, H2O, and Ice Cloud with the precisions in a few to several tens percents. Theoretical observation capability was studied with error analysis. The altitude region of observation is from the upper troposphere to the mesopouse. SMILES early results will be shown with global distributions (L3 data). The early comparison/validation of ozone performed with several satellite data, such as MLS, ACE, OSIRIS and Odin.SMR. The statistical analysis showed the differences were less of 5 percent between SMILES and other satellites data validated. This value was consistent with theoretical capability. This super technology may allow us to open new issues in atmospheric science.

  16. Period Evolution of Double White Dwarf Binaries Under the Influence of Gravitational Wave Emissions

    Science.gov (United States)

    Martens, Kylee; Benacquista, Matt; Belczynski, Chris

    2016-03-01

    Compact objects, such as Double White Dwarf (DWD) binaries, are the most populous producers of gravitational waves (GW) at low frequencies. The gravitational radiation (GR) emitted from the Galactic DWD binary population will create an unresolvable signal known as the confusion noise-limit (CNL) in the space-based evolved Laser Interferometer Space Antenna (eLISA). It is predicted that many thousand DWD binary signals will rise above the CNL and create resolvable GW signals. In previous work, Heather Johnson, from the University of Texas-Austin, produced ~61 million DWD systems using the binary population features in the StarTrack population synthesis code created by Chris Belczynski. We have created an evolutionary code that continues the period evolution of the DWD binaries under the effects of GR. Our present model only accounts for detached binary systems, but we are working on incorporating more features. Current period evolution models often extrapolate data based on smaller binary populations, however our model will utilize ~61 million binary systems in order to avoid inaccuracies.We then use two standard cylindrical density distributions to populate a galaxy with the evolved systems. We also discuss correlations between the progenitor binaries and the eLISA sources.

  17. Evaluation of Wave Propagation Properties during a True-Triaxial Rock Fracture Experiment using Acoustic Emission Frequency Characteristics

    Science.gov (United States)

    Goodfellow, S. D.; Ghofrani Tabari, M.; Nasseri, M. B.; Young, R.

    2013-12-01

    A true-triaxial deformation experiment was conducted to study the evolution of wave propagation properties by using frequency characteristics of AE waveforms to diagnose the state of fracturing in a sample of sandstone. Changes in waveform frequency content has been interpreted as either the generation of progressively larger fractures or the relative attenuation of high-frequency wave components as a result of micro-crack formation. A cubic sample of Fontainebleau sandstone was initially loaded to a stress state of σ1 = σ2 = 35 MPa, σ3 = 5 MPa at which point σ1¬ was increased until failure. Acoustic emission (AE) activity was monitored by 18 PZT transducers, three embedded in each platen. The sensor amplitude response spectrum was determined by following an absolute source calibration procedure and showed a relatively constant sensitivity in the frequency range between 20 kHz and 1200 kHz. Amplified waveforms were continuously recorded at a sampling rate of 10 MHz and 12-bit resolution. Continuous acoustic emission waveforms were harvested to extract discrete events. Using a time-varying transverse isotropic velocity model, 48,502 events were locatable inside the sample volume. Prior to peak-stress, AE activity was associated with stable quasi-static growth of fractures coplanar with σ1 and σ2 located near the platen boundaries. In the post peak-stress regime, fracture growth displays unstable ¬dynamic propagation. Analysis of waveform frequency characteristics was limited to the pre peak-stress regime. Analysis of AE frequency characteristics was conducted on all 48,502 located AE events; each event file containing 18 waveforms of varied quality. If the signal to noise ratio was greater than 5, the waveforms power spectrum was estimated and the source-receiver raypath vector was calculated. The power spectrum of each waveform was divided into three frequency bands (Low: 100 - 300 kHz, Medium: 300 - 600 kHz and High: 600 - 1000 kHz) and the power in each

  18. Excitation of electrostatic waves in the electron cyclotron frequency range during magnetic reconnection in laboratory overdense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kuwahata, A., E-mail: kuwahata@ts.t.u-tokyo.ac.jp [Graduate School of Engineering, The University of Tokyo, Tokyo 113-8656 (Japan); Igami, H. [National Institute for Fusion Science, Toki 509-5292 (Japan); Kawamori, E. [Institute of Space and Plasma Sciences, National Cheng Kung University, Tainan 70101, Taiwan (China); Kogi, Y. [Fukuoka Institute of Technology, Fukuoka 811-0295 (Japan); Inomoto, M.; Ono, Y. [Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561 (Japan)

    2014-10-15

    We report the observation of electromagnetic radiation at high harmonics of the electron cyclotron frequency that was considered to be converted from electrostatic waves called electron Bernstein waves (EBWs) during magnetic reconnection in laboratory overdense plasmas. The excitation of EBWs was attributed to the thermalization of electrons accelerated by the reconnection electric field around the X-point. The radiative process discussed here is an acceptable explanation for observed radio waves pulsation associated with major flares.

  19. Terahertz wave emission from intrinsic Josephson junctions in high- Tc superconductors

    Science.gov (United States)

    Ozyuzer, L.; Simsek, Y.; Koseoglu, H.; Turkoglu, F.; Kurter, C.; Welp, U.; Koshelev, A. E.; Gray, K. E.; Kwok, W. K.; Yamamoto, T.; Kadowaki, K.; Koval, Y.; Wang, H. B.; Müller, P.

    2009-11-01

    Recently, we experimentally demonstrated that rectangular mesa structures of intrinsic Josephson junctions (IJJ) in Bi2Sr2CaCu2O8+d (Bi2212) can be used as a compact solid-state generator of continuous, coherent and polarized terahertz (THz) radiation. In the present work, we will exhibit tall mesas (over 600 junctions) which were fabricated using UV lithography, e-beam lithography with photoresist and e-beam lithography with a Ti selective etching technique. We will present measurements of the c-axis resistance as a function of temperature and of current-voltage characteristics of THz emitting mesas with lateral sizes ranging from 30 × 300 to 100 × 300 µm2. Furthermore, we will discuss the dependence of the characteristics of the mesa structures on the oxygen doping level of the Bi2212 crystals. We will also experimentally show that the voltage-frequency relation of the ac Josephson effect has to match the cavity resonance for successful emission.

  20. Waves on a Hele-Shaw Cell: Simulations of Acoustic Emissions During Aerofracture

    Science.gov (United States)

    Turkaya, Semih; Toussaint, Renaud; Kvalheim Eriksen, Fredrik; Daniel, Guillaume; Grude Flekkøy, Eirik; Jørgen Måløy, Knut

    2016-04-01

    In this work, we develop a numerical model to explain the lab scale experimental setup [1] modeling the aerofractures in a porous medium. The mentioned experimental setup consists in a rectangular Hele-Shaw cell with three closed boundaries and one semi-permeable boundary which enables the flow of the fluid but not the solid particles. During the experiments, the fluid (pressurized air) is injected into the system with a constant injection pressure from the point opposite to the semi-permeable boundary. At the large enough injection pressures, the fluid also displaces grains (80 μm grain size) and creates channels and fractures towards the semi-permeable boundary. This analogue model is developed in a linear geometry, with confinement and at a lower porosity to study the instabilities developing during the fast motion of a fluid in dense porous materials: fracturing, fingering, and channeling. Different sources of the signal (air vibration in the carved area, changes in the effective stress due to fluid-solid interactions [2]) are separately analyzed and are investigated further using a far field approximation of Lamb waves presented by Goyder & White [3]. In the analysis phase, power spectrum of different timewindows (5 ms) obtained from the recorded signal are computed. Then, the evolution of this power spectrum is compared with the experimental findings. In the power spectrum, it is possible to see some characteristic structure like peaks in specific frequency ranges. These "peaks" are strongly influenced by the size and branching of the channels, compaction of the medium, vibration of air in the pores and the fundamental frequency of the plate. We found that, in the synthetic dataset, the peaks in the low frequency range (f Vibrational power flow from machines into built-up structures, part I: introduction and approximate analyses of beam and plate-like foundations." Journal of sound and vibration, 68.1 (1980): 59-75.

  1. ON DISCOVERING ELECTROMAGNETIC EMISSION FROM NEUTRON STAR MERGERS: THE EARLY YEARS OF TWO GRAVITATIONAL WAVE DETECTORS

    Energy Technology Data Exchange (ETDEWEB)

    Kasliwal, Mansi M. [The Observatories, Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Nissanke, Samaya [Theoretical Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)

    2014-07-01

    We present the first simulation addressing the prospects of finding an electromagnetic (EM) counterpart to gravitational wave (GW) detections during the early years of only two advanced detectors. The perils of such a search may have appeared insurmountable when considering the coarse ring-shaped GW localizations spanning thousands of square degrees using time-of-arrival information alone. Leveraging the amplitude and phase information of the predicted GW signal narrows the localization to arcs with a median area of only a few hundred square degrees, thereby making an EM search tractable. Based on the locations and orientations of the two LIGO detectors, we find that the GW sensitivity is limited to only two of the four sky quadrants. Thus, the rates of GW events with two interferometers is only ≈40% of the rate with three interferometers of similar sensitivity. Another important implication of the sky quadrant bias is that EM observatories in North America and Southern Africa would be able to systematically respond to GW triggers several hours sooner than Russia and Chile. Given the larger sky areas and the relative proximity of detected mergers, 1 m class telescopes with very wide-field cameras are well-positioned for the challenge of finding an EM counterpart. Identification of the EM counterpart amidst the larger numbers of false positives further underscores the importance of building a comprehensive catalog of foreground stellar sources, background active galactic nucleus and potential host galaxies in the local universe. This initial study is based on a small sample of 17 detected mergers; future works will expand this sample.

  2. The effect of plasma inhomogeneities on (i) radio emission generation by non-gyrotropic electron beams and (ii) particle acceleration by Langmuir waves

    Science.gov (United States)

    Tsiklauri, David

    2015-04-01

    Extensive particle-in-cell simulations of fast electron beams injected in a background magnetised plasma with a decreasing density profile were carried out. These simulations were intended to further shed light on a newly proposed mechanism for the generation of electromagnetic waves in type III solar radio bursts [1]. Here recent progress in an alternative to the plasma emission model using Particle-In-Cell, self-consistent electromagnetic wave emission simulations of solar type III radio bursts will be presented. In particular, (i) Fourier space drift (refraction) of non-gyrotropic electron beam-generated wave packets, caused by the density gradient [1,2], (ii) parameter space investigation of numerical runs [3], (iii) concurrent generation of whistler waves [4] and a separate problem of (iv) electron acceleration by Langmuir waves in a background magnetised plasma with an increasing density profile [5] will be discussed. In all considered cases the density inhomogeneity-induced wave refraction plays a crucial role. In the case of non-gyrotropic electron beam, the wave refraction transforms the generated wave packets from standing into freely escaping EM radiation. In the case of electron acceleration by Langmuir waves, a positive density gradient in the direction of wave propagation causes a decrease in the wavenumber, and hence a higher phase velocity vph = ω/k. The k-shifted wave is then subject to absorption by a faster electron by wave-particle interaction. The overall effect is an increased number of high energy electrons in the energy spectrum. [1] D. Tsiklauri, Phys. Plasmas 18, 052903 (2011); http://dx.doi.org/10.1063/1.3590928 [2] H. Schmitz, D. Tsiklauri, Phys. Plasmas 20, 062903 (2013); http://dx.doi.org/10.1063/1.4812453 [3] R. Pechhacker, D. Tsiklauri, Phys. Plasmas 19, 112903 (2012); http://dx.doi.org/10.1063/1.4768429 [4] M. Skender, D. Tsiklauri, Phys. Plasmas 21, 042904 (2014); http://dx.doi.org/10.1063/1.4871723 [5] R. Pechhacker, D. Tsiklauri

  3. Electrostatic structures in space plasmas: Stability of two-dimensional magnetic bernstein-greene-kruskal modes

    Science.gov (United States)

    Ng, C. S.; Soundararajan, S. J.; Yasin, E.

    2012-05-01

    Electrostatic structures have been observed in many regions of space plasmas, including the solar wind, the magnetosphere, the auroral acceleration region, and in association with shocks, turbulence, and magnetic reconnection. Due to potentially large amplitude of electric fields within these structures, their effects on particle heating, scattering, or acceleration can be important. One possible theoretical description of some of these structures is the concept of Bernstein-Greene-Kruskal (BGK) modes, which are exact nonlinear solutions of the Vlasov-Poisson system of equations in collisionless kinetic theory. BGK modes have been studied extensively for many decades, predominately in one dimension (1D), although there have been observations showing that some of these structures have clear 3D features. While there have been approximate solutions of higher dimensional BGK modes, an exact 3D BGK mode solution in a finite magnetic field has not been found yet. Recently we have constructed exact solutions of 2D BGK modes in a magnetized plasma with finite magnetic field strength in order to gain insights of the ultimate 3D theory [Ng, Bhattacharjee, and Skiff, Phys. Plasmas 13, 055903 (2006)]. Based on the analytic form of these solutions, as well as Particle-in-Cell (PIC) simulations, we will present numerical studies of their stability for different levels of background magnetic field strength.

  4. The Submillimeter Wave Electron Cyclotron Emission Diagnostic for the Alcator C-Mod Tokamak.

    Science.gov (United States)

    Hsu, Thomas C.

    This thesis describes the engineering design, construction, and operation of a high spatial resolution submillimeter wave diagnostic for electron temperature measurements on Alcator C-Mod. Alcator C-Mod is a high performance compact tokamak capable of producing diverted, shaped plasmas with a major radius of 0.67 meters, minor radius of 0.21 centimeters, plasma current of 3 MA. The maximum toroidal field is 9 Tesla on the magnetic axis. The ECE diagnostic includes three primary components: a 10.8 meter quasioptical transmission line, a rapid scanning Michelson interferometer, and a vacuum compatible calibration source. Due to the compact size and high field of the tokamak the ECE system was designed to have a spectral range from 100 to 1000 GHz with frequency resolution of 5 GHz and spatial resolution of one centimeter. The beamline uses all reflecting optical elements including two off-axis parabolic mirrors with diameters of 20 cm. and focal lengths of 2.7 meters. Techniques are presented for grinding and finishing the mirrors to sufficient surface quality to permit optical alignment of the system. Measurements of the surface figure confirm the design goal of 1/4 wavelength accuracy at 1000 GHz. Extensive broadband tests of the spatial resolution of the ECE system are compared to a fundamental mode Gaussian beam model, a three dimensional vector diffraction model, and a geometric optics model. The Michelson interferometer is a rapid scanning polarization instrument which has an apodized frequency resolution of 5 GHz and a minimum scan period of 7.5 milliseconds. The novel features of this instrument include the use of precision linear bearings to stabilize the moving mirror and active counterbalancing to reduce vibration. Beam collimation within the instrument is done with off-axis parabolic mirrors. The Michelson also includes a 2-50 mm variable aperture and two signal attenuators constructed from crossed wire grid polarizers. To make full use of the advantages

  5. Full wave simulations of fast wave mode conversion and lower hybrid wave propagation in tokamaks

    DEFF Research Database (Denmark)

    Wright, J.C.; Bonoli, P.T.; Brambilla, M.;

    2004-01-01

    Fast wave (FW) studies of mode conversion (MC) processes at the ion-ion hybrid layer in toroidal plasmas must capture the disparate scales of the FW and mode converted ion Bernstein and ion cyclotron waves. Correct modeling of the MC layer requires resolving wavelengths on the order of k......). Two full wave codes, a massively-parallel-processor (MPP) version of the TORIC-2D finite Larmor radius code [M. Brambilla, Plasma Phys. Controlled Fusion 41, 1 (1999)] and also an all orders spectral code AORSA2D [E. F. Jaeger , Phys. Plasmas 9, 1873 (2002)], have been developed which for the first...... time are capable of achieving the resolution and speed necessary to address mode conversion phenomena in full two-dimensional (2-D) toroidal geometry. These codes have been used in conjunction with theory and experimental data from the Alcator C-Mod [I. H. Hutchinson , Phys. Plasmas 1, 1511 (1994)] to...

  6. Assessment of risks of EMI for personal medical electronic devices (PMEDs) from emissions of millimeter-wave security screening systems

    Science.gov (United States)

    Witters, Donald; Bassen, Howard; Guag, Joshua; Addissie, Bisrat; LaSorte, Nickolas; Rafai, Hazem

    2013-06-01

    This paper describes research and testing of a representative group of high priority body worn and implantable personal medical electronic devices (PMEDs) for exposure to millimeter wave (MMW) advanced imaging technology (AIT) security systems used at airports. The sample PMEDs included in this study were implantable cardiac pacemakers, ICDs, neurostimulators and insulin pumps. These PMEDs are designed and tested for susceptibility to electromagnetic interference (EMI) under the present standards for medical device electromagnetic compatibility (EMC). However, the present standards for medical equipment do not address exposure to the much higher frequency fields that are emitted by MMW security systems. Initial AIT emissions measurements were performed to assess the PMED and passenger exposures. Testing protocols were developed and testing methods were tailored to the type of PMED. In addition, a novel exposure simulation system was developed to allow controlled EMC testing without the need of the MMW AIT system. Methodology, test results, and analysis are presented, along with an assessment of the human exposure and risks for PMED users. The results on this study reveal no effects on the medical devices from the exposure to the MMW security system. Furthermore, the human exposure measurements and analysis showed levels well below applicable standard, and the risks for PMED users and others we assessed to be very low. These findings apply to the types of PMEDs used in the study though these findings might suggest that the risks for other, similar PMEDs would likely be similar.

  7. Excitation of Large-ktheta Ion-Berstein Waves in Tokamaks

    OpenAIRE

    Valeo, E. J.; Fisch, N. J.

    1995-01-01

    The mode-converted ion-Bernstein wave excited in tokamaks is shown to exhibit certain very interesting behavior, including the attainment of very small poloidal phase velocities, the reversal of poloidal direction, and up-down asymmetries in propagation and damping. Because of these effects, this wave holds promise for channeling {$\\alpha$-particle}\\ power to ions, something that would make a tokamak fusion reactor far more attractive than presently envisioned.

  8. Topology of relativistic refractive index surfaces for electron cyclotron waves

    International Nuclear Information System (INIS)

    The dispersion of electron cyclotron waves in a weakly relativistic Maxwellian plasma is investigated. It is shown that the apparently very complicated picture of the coupling of the extraordinary (X) mode to Bernstein waves can be accounted for in a simple way by considering the refractive indices as Riemann-like surfaces in the Clemmow-Mullaly-Allis (CMA) parameter space, (ωp2/ω2, ωc/ω), and by introducing a few topological concepts from the analysis of complex functions. A detailed study is made of the surface representing the X mode for perpendicular propagation, with special attention given to the connection between this mode and Gross-Bernstein modes. For perpendicular propagation non-transcendental approximations to the relativistic refractive indices for X and O modes can be given. We show that these approximations are good up to ∼ 25 keV and, at frequencies up to the second harmonic of the electron cyclotron frequency, the X mode approximation also accounts correctly for the connection of the X mode to Bernstein modes. The accuracy and the numerical efficiency of the approximations make them well suited for routine calculations for millimetre wave applications in fusion plasmas, including the analysis of X mode and O mode reflectometry. (author)

  9. Effect of planetary waves on cooling the upper mesosphere and lower thermosphere by the CO2 15-µm emission

    Directory of Open Access Journals (Sweden)

    A. I. Pogoreltsev

    2004-11-01

    Full Text Available The steady-state 2-D linearized model of global-scale waves, calibrated according to available observations, is used to evaluate planetary-wave perturbations of temperature from the surface up to the height of about 165km. The maximum order of perturbation amplitudes in the upper mesosphere and lower thermosphere is found to be 15K for the ultra-fast Kelvin wave (UFKW of the 3.5-day period, 8K for the 10-day wave, 5K for the 2- and 16-day waves, and 2K for the 5-day wave. The wave-caused variation in heat influx in the CO2 15-µm band, averaged over the wave period, depends on both the amplitude of temperature and temperature profile in the atmosphere unperturbed by the wave. An additional increase in radiative cooling is the prevailing effect of planetary waves in the upper mesosphere and lower thermosphere. The UFKW results in an increasing cooling rate up to ~0.1 of the cooling rate in the unperturbed atmosphere. The tangible contributions of the 2-, 10-, and 16-day waves are questionable. The contribution of the 5-day wave is negligible.

  10. Verification of nonlinear particle simulation of radio frequency waves in tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Kuley, A., E-mail: akuley@uci.edu; Lin, Z. [Department of Physics and Astronomy, University of California Irvine, California 92697 (United States); Bao, J. [Department of Physics and Astronomy, University of California Irvine, California 92697 (United States); Fusion Simulation Center, Peking University, Beijing 100871 (China); Wei, X. S.; Xiao, Y. [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Zhang, W. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Sun, G. Y. [Department of Physics, Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China); Fisch, N. J. [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540 (United States); Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2015-10-15

    Nonlinear simulation model for radio frequency waves in fusion plasmas has been developed and verified using fully kinetic ion and drift kinetic electron. Ion cyclotron motion in the toroidal geometry is implemented using Boris push in the Boozer coordinates. Linear dispersion relation and nonlinear particle trapping are verified for the lower hybrid wave and ion Bernstein wave (IBW). Parametric decay instability is observed where a large amplitude pump wave decays into an IBW sideband and an ion cyclotron quasimode (ICQM). The ICQM induces an ion perpendicular heating, with a heating rate proportional to the pump wave intensity.

  11. Verification of nonlinear particle simulation of radio frequency waves in tokamak

    International Nuclear Information System (INIS)

    Nonlinear simulation model for radio frequency waves in fusion plasmas has been developed and verified using fully kinetic ion and drift kinetic electron. Ion cyclotron motion in the toroidal geometry is implemented using Boris push in the Boozer coordinates. Linear dispersion relation and nonlinear particle trapping are verified for the lower hybrid wave and ion Bernstein wave (IBW). Parametric decay instability is observed where a large amplitude pump wave decays into an IBW sideband and an ion cyclotron quasimode (ICQM). The ICQM induces an ion perpendicular heating, with a heating rate proportional to the pump wave intensity

  12. The Level 2 research product algorithms for the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES

    Directory of Open Access Journals (Sweden)

    P. Baron

    2011-10-01

    Full Text Available This paper describes the algorithms of the level-2 research (L2r processing chain developed for the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES. The chain has been developed in parallel to the operational chain for conducting researches on calibration and retrieval algorithms. L2r chain products are available to the scientific community. The objective of version 2 is the retrieval of the vertical distribution of trace gases in the altitude range of 18–90 km. A theoretical error analysis is conducted to estimate the retrieval feasibility of key parameters of the processing: line-of-sight elevation tangent altitudes (or angles, temperature and ozone profiles. While pointing information is often retrieved from molecular oxygen lines, there is no oxygen line in the SMILES spectra, so the strong ozone line at 625.371 GHz has been chosen. The pointing parameters and the ozone profiles are retrieved from the line wings which are measured with high signal to noise ratio, whereas the temperature profile is retrieved from the optically thick line center. The main systematic component of the retrieval error was found to be the neglect of the non-linearity of the radiometric gain in the calibration procedure. This causes a temperature retrieval error of 5–10 K. Because of these large temperature errors, it is not possible to construct a reliable hydrostatic pressure profile. However, as a consequence of the retrieval of pointing parameters, pressure induced errors are significantly reduced if the retrieved trace gas profiles are represented on pressure levels instead of geometric altitude levels. Further, various setups of trace gas retrievals have been tested. The error analysis for the retrieved HOCl profile demonstrates that best results for inverting weak lines can be obtained by using narrow spectral windows.

  13. Comparison of ozone profiles between Superconducting Submillimeter-Wave Limb-Emission Sounder and worldwide ozonesonde measurements

    Science.gov (United States)

    Imai, Koji; Fujiwara, Masatomo; Inai, Yoichi; Manago, Naohiro; Suzuki, Makoto; Sano, Takuki; Mitsuda, Chihiro; Naito, Yoko; Hasebe, Fumio; Koide, Takashi; Shiotani, Masato

    2013-11-01

    compared ozone profiles measured by the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) with those taken at worldwide ozonesonde stations. To assess the quality of the SMILES version 2.3 ozone data for 16-30 km, 601 ozonesonde profiles were compared with the coincident SMILES ozone profiles. The agreement between SMILES and ozonesonde measurements was generally good within 5%-7% for 18-30 km at middle and high latitudes but degraded below 18 km. At low latitudes, however, the SMILES ozone data showed larger values (~6%-15% for 20-26 km) than those at middle and high latitudes. To explain this bias, we explored some possible issues in the ozonesonde measurement system. One possibility is due to a pressure bias in radiosonde measurements with a pressure sensor, but it would be within a few percent. We also examined an issue of the ozonesonde's response time. The response time was estimated from ozonesonde measurements with ascending and descending profiles showing clear difference, by using the time lag correction method to minimize the difference between them. Our estimation shows 28 s on average which is a similar value derived by prelaunch preparation. By applying this correction to the original profiles, we found a negative bias of the ascending ozonesonde measurement more than 7% at 20 km in the equatorial latitude where the vertical gradient of ozone is steep. The corrected ozonesonde profiles showed better agreement with the SMILES data. We suggest that the response time of ozonesondes could create a negative bias, particularly in the lower stratosphere at equatorial latitudes.

  14. The Level 2 research product algorithms for the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES)

    Science.gov (United States)

    Baron, P.; Urban, J.; Sagawa, H.; Möller, J.; Murtagh, D. P.; Mendrok, J.; Dupuy, E.; Sato, T. O.; Ochiai, S.; Suzuki, K.; Manabe, T.; Nishibori, T.; Kikuchi, K.; Sato, R.; Takayanagi, M.; Murayama, Y.; Shiotani, M.; Kasai, Y.

    2011-10-01

    This paper describes the algorithms of the level-2 research (L2r) processing chain developed for the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES). The chain has been developed in parallel to the operational chain for conducting researches on calibration and retrieval algorithms. L2r chain products are available to the scientific community. The objective of version 2 is the retrieval of the vertical distribution of trace gases in the altitude range of 18-90 km. A theoretical error analysis is conducted to estimate the retrieval feasibility of key parameters of the processing: line-of-sight elevation tangent altitudes (or angles), temperature and ozone profiles. While pointing information is often retrieved from molecular oxygen lines, there is no oxygen line in the SMILES spectra, so the strong ozone line at 625.371 GHz has been chosen. The pointing parameters and the ozone profiles are retrieved from the line wings which are measured with high signal to noise ratio, whereas the temperature profile is retrieved from the optically thick line center. The main systematic component of the retrieval error was found to be the neglect of the non-linearity of the radiometric gain in the calibration procedure. This causes a temperature retrieval error of 5-10 K. Because of these large temperature errors, it is not possible to construct a reliable hydrostatic pressure profile. However, as a consequence of the retrieval of pointing parameters, pressure induced errors are significantly reduced if the retrieved trace gas profiles are represented on pressure levels instead of geometric altitude levels. Further, various setups of trace gas retrievals have been tested. The error analysis for the retrieved HOCl profile demonstrates that best results for inverting weak lines can be obtained by using narrow spectral windows.

  15. The Level 2 research product algorithms for the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES

    Directory of Open Access Journals (Sweden)

    P. Baron

    2011-06-01

    Full Text Available This paper describes the algorithms of the level-2 research (L2r processing chain developed for the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES. The chain has been developed in parallel to the operational chain for conducting researches on calibration and retrieval algorithms. L2r chain products are available to the scientific community. The objective of version 2 is the retrieval of the vertical distribution of trace gases in the altitude range of 18–90 km. An theoretical error analysis is conducted to estimate the retrieval feasibility of key parameters of the processing: line-of-sight elevation tangent altitudes (or angles, temperature and O3 profiles. The line-of-sight tangent altitudes are retrieved between 20 and 50 km from the strong ozone (O3 line at 625.371 GHz, with low correlation with the O3 volume-mixing ratio and temperature retrieved profiles. Neglecting the non-linearity of the radiometric gain in the calibration procedure is the main systematic error. It is large for the retrieved temperature (between 5–10 K. Therefore, atmospheric pressure can not be derived from the retrieved temperature, and, then, in the altitude range where the line-of-sight tangent altitudes are retrieved, the retrieved trace gases profiles are found to be better represented on pressure levels than on altitude levels. The error analysis for the retrieved HOCl profile demonstrates that best results for inverting weak lines can be obtained by using narrow spectral windows. Future versions of the L2r algorithms will improve the temperature/pressure retrievals and also provide information in the upper tropospheric/lower stratospheric region (e.g., water vapor, ice content, O3 and on stratospheric and mesospheric line-of-sight winds.

  16. A full wave code for ion cyclotron waves in toroidal plasmas

    International Nuclear Information System (INIS)

    The code TORIC solves the finite Larmor radius wave equations in the ion cyclotron frequency range in arbitrary axisymmetric toroidal geometry. The model used describes the compressional and torsional Alfven waves (or, depending on the parallel phase velocity, the kinetic counterpart of the latter), and ion Bernstein waves excited by mode conversion near the first ion cyclotron harmonic. In the ion response the broadening of the absorption regions due to the finite width of the cyclotron resonance of individual ions in toroidal geometry is taken into account. The parallel component of the wave electric field is evaluated on the same footing as the transverse ones; the response of the electrons includes Landau damping, Transit Time damping and the mixed term. The numerical approach uses a spectral representation of the solution in the poloidal angle θ, and cubic finite elements in the radial variable ψ. Great flexibility is provided in the way ion Bernstein waves excited by mode conversion are damped when their wavelength becomes comparable with the ion Larmor radius, in the regularization of Alfven resonances, and in the treatment of the outer plasma layers. As an option, we have also implemented the Order Reduction Algorithm, which provides a particularly fast, yet accurate evaluation of the power deposition profiles in toroidal geometry. Thee present report describes the model and its numerical implementation, and provides the information needed to use the code. A few examples illustrating applications of TORIC are also included. (orig.)

  17. Nonlinear coupling of O- and X-mode radio emission and Alfven waves in the solar corona

    International Nuclear Information System (INIS)

    The nonlinear coupling of extraordinary and ordinary waves via kinetic Alfven waves (KAWs) is investigated on the basis of two fluid magnetohydrodynamics. The equation governing the time dependence of electric field of excited O-mode is found. We estimate the time of effective coupling between modes and corresponding interaction distance in solar corona. Our theoretical results show that the X- and O-mode couplings via Alfven waves can be efficient depolarization mechanism for the coronal radioemission

  18. Excitation of parametric instabilities by radio waves in the ionosphere.

    Science.gov (United States)

    Fejer, J. A.; Leer, E.

    1972-01-01

    The excitation of parametric instabilities by radio waves in a magnetoplasma is discussed. A uniform medium is assumed and linear approximations are used. Excitation by a pump wave of ordinary polarization is hardly affected by the magnetic field. Low or zero frequency ion waves and high frequency Langmuir waves are excited simultaneously. For an extraordinary pump wave, the excited high frequency electrostatic waves are in the Bernstein mode. The threshold is slightly higher and excitation can occur only within certain 'allowed' frequency bands. A new type of parametric instability in which the excited waves are electromagnetic in nature and which is more strongly affected by the inhomogeneous nature of the medium is discussed qualitatively.

  19. Bernstein's theory of pedagogic discourse as a theoretical framework for educators studying student radiographers' interpretation of normality vs. abnormality

    International Nuclear Information System (INIS)

    Purpose: To acknowledge the tacit rules underpinning academic practice of undergraduate radiographers in determining normality vs. abnormality when appraising skeletal images. Methodology: Twelve students were interviewed (individually) using in-depth semi-structured questions. Interviews were mediated through a PowerPoint presentation containing two digital X-ray images. Each image was based on a level of expertise; the elementary (Case 1) and the complicated (Case 2). The questions were based on regular ‘frames’ created from observing tutor–student contact in class, and then validated through a group interview. Bernstein's theory of pedagogic discourse was then utilised as a data analysis instrument to determine how third year diagnostic radiography students interpreted X-ray images, in relation to the ‘recognition’ and ‘realisation’ rules of the Educational Theoretical Framework. Conclusion: Bernstein's framework has made it possible to specify, in detail, how issues and difficulties are formed at the level of the acquirer during interpretation. The recognition rules enabled students to meaningfully recognise what trauma characteristics can be associated with the image and the demands of a detailed scrutiny so as to enact a competent interpretation. Realisation rules, made it possible for students to establish their own systematic approach and realise legitimate meanings of normality and abnormality. Whereas obvious or visible trauma generated realisation rules (represented via homogenous terminology), latent trauma authorised students to deviate from legitimate meanings. The latter rule, in this context, has directed attention to the student issue of visioning abnormality when images are normal

  20. Stimulated electromagnetic emission and plasma line during pump wave frequency stepping near 4th electron gyroharmonic at HAARP

    Science.gov (United States)

    Grach, Savely; Sergeev, Evgeny; Shindin, Alexey; Mishin, Evgeny; Watkins, Brenton

    Concurrent observations of stimulated (secondary) electromagnetic emissions (SEE) and incoherent plasma line (PL) backscatter from the MUIR radar during HF pumping of the ionosphere by the HAARP heating facility (62.4(°) °N, 145.15(°) W, magnetic inclination α = 75.8^circ) with the pump wave (PW) frequency sweeps about the fourth electron gyroharmonic (4f_c) are presented. The PW frequency f0 was changed every 0.2 s in a 1-kHz step, i.e. with the rate of r_{f_0}=5 kHz/s. PW was transmitted at the magnetic zenith (MZ). Prior to sweeping, PW was transmitted continuously (CW) during 2 min at f_0 = 5730 kHz 4f_c, namely BUM_S and BUM_D. The former (stationary broad upshifted maxiμm) peaks at Delta f_{BUMs} approx f0 - nfc (d) + 15-20 kHz and is a typical SEE spectral feature. The latter, the dynamic BUM_D at smaller Delta f, is observed only at high pump powers (ERP=1.7 GW) and corresponds to artificial descending plasma layers created in the F-region ionosphere [1]. In the experiment in question, the BUM_D was present for f_0> f^*, where f^* was 5805-5815 kHz during stepping up and sim 10 kHz less for stepping down, and located 8-10 km below the background F-layer. The miniμm DM which indicated that f_0=4f_c=f_{uh} in the background ionospheric plasma, was sim 5760 kHz. The PL was observed only for f_0 4f_c. In this case we obtained Delta f_g sim 8-13 kHz corresponding to Delta h sim - 4 km. The PL has never been observed for f_0>f^*$. \\ 1. Sergeev E., Grach S., et al. //Phys. Rev. Lett., 110 (2013), 065002.

  1. Bernstein, Nils: „kennen sie mich herren/meine damen und herren”. Phraseologismen in Moderner Lyrik am Beispiel von Ernst Jandl und Nicanor Parra.

    OpenAIRE

    Urška Valenčič Arh

    2014-01-01

    Bernstein, Nils (2011): „kennen sie mich herren/meine damen und herren”. Phraseologismen in Moderner Lyrik am Beispiel von Ernst Jandl und Nicanor Parra. Würzburg: Königshausen&Neumann. ISBN: 978-3-8260-4699-5, mehka vezava, 262 strani, 38,00 EUR

  2. Bernstein, Nils: „kennen sie mich herren/meine damen und herren”. Phraseologismen in Moderner Lyrik am Beispiel von Ernst Jandl und Nicanor Parra.

    Directory of Open Access Journals (Sweden)

    Urška Valenčič Arh

    2014-01-01

    Full Text Available Bernstein, Nils (2011: „kennen sie mich herren/meine damen und herren”. Phraseologismen in Moderner Lyrik am Beispiel von Ernst Jandl und Nicanor Parra. Würzburg: Königshausen&Neumann. ISBN: 978-3-8260-4699-5, mehka vezava, 262 strani, 38,00 EUR

  3. High-performance continuous-wave room temperature 4.0-μm quantum cascade lasers with single-facet optical emission exceeding 2 W

    OpenAIRE

    Lyakh, A; Maulini, R; Tsekoun, A; Go, R; Von der Porten, S.; Pflügl, C.; Diehl, L; Capasso, Federico; C. Kumar N. Patel

    2010-01-01

    A strain-balanced, AlInAs/InGaAs/InP quantum cascade laser structure, designed for light emission at 4.0 μm using nonresonant extraction design approach, was grown by molecular beam epitaxy. Laser devices were processed in buried heterostructure geometry. An air-cooled laser system incorporating a 10-mm × 11.5-μm laser with antireflection-coated front facet and high-reflection-coated back facet delivered over 2 W of single-ended optical power in a collimated beam. Maximum continuous-wave room...

  4. Investigations of the cathode region of an argon arc plasma by degenerate four-wave mixing laser spectroscopy and optical emission spectroscopy

    International Nuclear Information System (INIS)

    Degenerate four-wave mixing (DFWM) laser spectroscopy was used in local studies of atmospheric pressure argon plasma generated in a free-burning arc. The results of plasma diagnostics using the DFWM method were compared to the results obtained with optical emission measurements. In the cathode region of the arc the maxima of both the DFWM signal and the emission coefficient for the 696.5 nm Ar I line depend on the distance from the cathode tip. This effect proves the departure of the plasma state from local thermal equilibrium (LTE) as it has been reported by many authors. On the other hand the Stark shifts of the 696.5 nm Ar I line determined by the DFWM method in relation to plasma diagnostic results show no deviations from LTE on the arc axis down to 1.0 mm from the cathode tip

  5. MORA DEBITORIS AND THE PRINCIPLE OF STRICT LIABILITY: SCOIN TRADING (PTY LTD V BERNSTEIN 2011 2 SA 118 (SCA

    Directory of Open Access Journals (Sweden)

    SJ Cornelius

    2012-12-01

    Full Text Available Parties generally enter into contractual relations with the sincere intention to fulfil all the obligations created in terms of their contract. However, for various reasons, parties sometimes do not comply with the terms of their contract. Where a party fails to perform at the agreed date and time or after receiving a demand from the creditor, the debtor commits breach of contract in the form of mora debitoris. The question then arises whether or not a debtor would also commit breach in the form of mora debitoris if the delay in performance cannot be attributed to wilful disregard of the contract or a negligent failure to perform on time. This was the question which the court had to determine in Scoin Trading (Pty Ltd v Bernstein.

  6. Two-Dimensional Current Carrying Bernstein-Greene-Kruskal (BGK) Modes for the Vlasov-Poisson-Ampere System

    Science.gov (United States)

    Ng, C. S.

    2014-10-01

    Electrostatic structures have been observed in many regions of space plasmas, including the solar wind, the magnetosphere, the auroral acceleration region. One possible theoretical description of some of these structures is the concept of Bernstein-Greene-Kruskal (BGK) modes, which are exact nonlinear steady-state solutions of the Vlasov-Poisson system of equations in collisionless kinetic theory. We generalize exact solutions of two-dimensional BGK modes in a magnetized plasma with finite magnetic field strength to cases with azimuthal magnetic fields so that these structures carry electric current as well as steady electric and magnetic fields. Such nonlinear solutions now satisfy exactly the Vlasov-Poisson-Ampere system of equations. This work is supported by a National Science Foundation Grant PHY-1004357.

  7. Ion cyclotron wave excitation by double resonance coupling

    International Nuclear Information System (INIS)

    A modulated high frequency wave is used to remotely excite low frequency oscillations in a linear, strongly magnetized plasma column. An electromagnetic wave is launched as an extraordinary mode across the plasma by an external waveguide in the Upper Hybrid frequency regime f=fUH=fce=8 GHz, with P≤2 W. By frequency modulating (at fFM=1-60 kHz, with fci≅30 kHz) the pump wave, the resonant layer is swept radially across the profile and perpendicularly to the field lines at f=fFM. The resulting radial oscillation of the electron linear and non linear pressure can be considered to act as a source term for the ion wave. A localized virtual antenna is thereby created inside the plasma. Measurements of the ion dielectric response (interferograms and perturbed distribution functions) via laser induced fluorescence identify the two branches (forward, or ion-acoustic-like, and backward, or Bernstein, modes) of the electrostatic dispersion relation in the ion cyclotron frequency range. By changing the modulation bandwidth, and thus the spatial excursion of the oscillating resonant layer, a control on the perpendicular wavelength of the excited mode can be exerted. In particular, the possibility of selective excitation of the ion Bernstein wave is demonstrated experimentally. (author) 38 refs., 13 figs

  8. Investigation of electrostatic waves in the ion cyclotron range of frequencies in L-4 and ACT-1

    International Nuclear Information System (INIS)

    Electrostatic waves in the ion cyclotron range of frequencies (ICRF) were studied in the Princeton L-4 and ACT-1 devices for approximately ten years, from 1975 to 1985. The investigation began in the L-4 linear device, looking for the parametric excitation of electrostatic ion cyclotron waves in multi-ion-species plasmas. In addition, this investigation verified multi-ion-species effects on the electrostatic ion cyclotron wave dispersion religion including the ion-ion hybrid resonance. Finite-Larmor-radius modification of the wave dispersion relation was also observed, even for ion temperatures of Ti ∼ 1/40 eV. Taking advantage of the relatively high field and long device length of L-4, the existence of the cold electrostatic ion cyclotron wave (CES ICW) was verified. With the arrival of the ACT-1 toroidal device, finite-Larmor-radius (FLR) waves were studied in a relatively collisionless warm-ion hydrogen plasma. Detailed investigations of ion Bernstein waves (IBW) included the verification of mode-transformation in their launching, their wave propagation characteristics, their absorption, and the resulting ion heating. This basic physics activity played a crucial role in developing a new reactor heating concept termed ion Bernstein wave heating. Experimental research in the lower hybrid frequency range confirmed the existence of FLR effects near the lower hybrid resonance, predicted by Stix in 1965. In a neon plasma with a carefully placed phased wave exciter, the neutralized ion Bernstein wave was observed for the first time. Using a fastwave ICRF antenna, two parasitic excitation processes for IBW -- parametric instability and density-gradient-driven excitation -- were also discovered. In the concluding section of this paper, a possible application of externally launched electrostatic waves is suggested for helium ash removal from fusion reactor plasmas

  9. Ion gyro-harmonic structuring in the stimulated radiation spectrum and optical emissions during electron gyro-harmonic heating

    Science.gov (United States)

    Mahmoudian, A.; Scales, W. A.; Bernhardt, P. A.; Samimi, A.; Kendall, E.; Ruohoniemi, J. M.; Isham, B.; Vega-Cancel, O.; Bordikar, M.

    2013-03-01

    Stimulated electromagnetic emissions (SEEs) are secondary radiation produced during active space experiments in which the ionosphere is actively heated with high power high frequency (HF) ground-based radio transmitters. Recently, there has been significant interest in ion gyro-harmonic structuring the SEE spectrum due to the potential for new diagnostic information available such as electron acceleration and creation of artificial ionization layers. These relatively recently discovered gyro-harmonic spectral features have almost exclusively been studied when the transmitting frequency is near the second electron gyro-harmonic frequency. The first extensive systematic experimental investigations of the possibility of these spectral features for third electron gyro-harmonic heating are provided here. Discrete spectral features shifted from the transmit frequency ordered by harmonics of the ion gyro-frequency were observed for third electron gyro-harmonic heating for the first time at a recent campaign at the High Frequency Active Auroral Research Program (HAARP) facility. These features were also closely correlated with a broader band feature at a larger frequency shift from the transmit frequency known as the downshifted peak (DP). The power threshold of these spectral features was measured, as well as their behavior with heater beam angle, and proximity of the transmit frequency to the third electron gyro-harmonic frequency. Comparisons were also made with similar spectral features observed during second electron gyro-harmonic heating during the same campaign. A theoretical model is provided that interprets these spectral features as resulting from parametric decay instabilities in which the pump field ultimately decays into high frequency upper hybrid/electron Bernstein and low frequency neutralized ion Bernstein IB and/or obliquely propagating ion acoustic waves at the upper hybrid interaction altitude. Coordinated optical and SEE observations were carried out

  10. Effective action approach to wave propagation in scalar QED plasmas

    CERN Document Server

    Shi, Yuan; Qin, Hong

    2016-01-01

    A relativistic quantum field theory with nontrivial background fields is developed and applied to study waves in plasmas. The effective action of the electromagnetic 4-potential is calculated ab initio from the standard action of scalar QED using path integrals. The resultant effective action is gauge invariant and contains nonlocal interactions, from which gauge bosons acquire masses without breaking the local gauge symmetry. To demonstrate how the general theory can be applied, we study a cold unmagnetized plasma and a cold uniformly magnetized plasma. Using these two examples, we show that all linear waves well-known in classical plasma physics can be recovered from relativistic quantum results when taking the classical limit. In the opposite limit, classical wave dispersion relations are modified substantially. In unmagnetized plasmas, longitudinal waves propagate with nonzero group velocities even when plasmas are cold. In magnetized plasmas, anharmonically spaced Bernstein waves persist even when plasma...

  11. Conference "Internet, Web, What's next?" on 26 June 1998 at CERN: Mark Bernstein, Vice President of CNN Interactive, describes the impact of the Web on world media and predicts what we can expect as the next developments

    CERN Document Server

    1998-01-01

    Conference "Internet, Web, What's next?" on 26 June 1998 at CERN: Mark Bernstein, Vice President of CNN Interactive, describes the impact of the Web on world media and predicts what we can expect as the next developments

  12. Tracking the CME-driven shock wave on 2012 march 5 and radio triangulation of associated radio emission

    Czech Academy of Sciences Publication Activity Database

    Magdalenic, J.; Marqué, C.; Krupař, Vratislav; Mierla, M.; Zhukov, A. N.; Rodriguez, L.; Maksimovic, M.; Cecconi, B.

    2014-01-01

    Roč. 791, č. 2 (2014), s. 1-14. ISSN 0004-637X R&D Projects: GA ČR GAP205/10/2279 Institutional support: RVO:68378289 Keywords : coronal mass ejections (CMEs) * shock waves * Sun: corona * Sun: flares * Sun: radio radiation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 5.993, year: 2014 http://iopscience.iop.org/0004-637X/791/2/115

  13. Energy-dispersed ions in the plasma sheet boundary layer and associated phenomena: Ion heating, electron acceleration, Alfvén waves, broadband waves, perpendicular electric field spikes, and auroral emissions

    Directory of Open Access Journals (Sweden)

    A. Keiling

    2006-10-01

    Full Text Available Recent Cluster studies reported properties of multiple energy-dispersed ion structures in the plasma sheet boundary layer (PSBL that showed substructure with several well separated ion beamlets, covering energies from 3 keV up to 100 keV (Keiling et al., 2004a, b. Here we report observations from two PSBL crossings, which show a number of identified one-to-one correlations between this beamlet substructure and several plasma-field characteristics: (a bimodal ion conics (<1 keV, (b field-aligned electron flow (<1 keV, (c perpendicular electric field spikes (~20 mV/m, (d broadband electrostatic ELF wave packets (<12.5 Hz, and (e enhanced broadband electromagnetic waves (<4 kHz. The one-to-one correlations strongly suggest that these phenomena were energetically driven by the ion beamlets, also noting that the energy flux of the ion beamlets was 1–2 orders of magnitude larger than, for example, the energy flux of the ion outflow. In addition, several more loosely associated correspondences were observed within the extended region containing the beamlets: (f electrostatic waves (BEN (up to 4 kHz, (g traveling and standing ULF Alfvén waves, (h field-aligned currents (FAC, and (i auroral emissions on conjugate magnetic field lines. Possible generation scenarios for these phenomena are discussed. In conclusion, it is argued that the free energy of magnetotail ion beamlets drove a variety of phenomena and that the spatial fine structure of the beamlets dictated the locations of where some of these phenomena occurred. This emphasizes the notion that PSBL ion beams are important for magnetosphere-ionosphere coupling. However, it is also shown that the dissipation of electromagnetic energy flux (at altitudes below Cluster of the simultaneously occurring Alfvén waves and FAC was larger (FAC being the largest than the dissipation of beam kinetic energy flux, and thus these two energy carriers contributed more to the energy transport on PSBL field lines

  14. Wave-particle resonance condition test for ion-kinetic waves in the solar wind

    Science.gov (United States)

    Narita, Y.; Marsch, E.; Perschke, C.; Glassmeier, K.-H.; Motschmann, U.; Comişel, H.

    2016-04-01

    Conditions for the Landau and cyclotron resonances are tested for 543 waves (identified as local peaks in the energy spectra) in the magnetic field fluctuations of the solar wind measured by the Cluster spacecraft on a tetrahedral scale of 100 km. The resonance parameters are evaluated using the frequencies in the plasma rest frame, the parallel components of the wavevectors, the ion cyclotron frequency, and the ion thermal speed. The observed waves show a character of the sideband waves associated with the ion Bernstein mode, and are in a weak agreement with the fundamental electron cyclotron resonance in spite of the ion-kinetic scales. The electron cyclotron resonance is likely taking place in solar wind turbulence near 1 AU (astronomical unit).

  15. Comparison between sensitivities of quality control methods using ultrasonic waves, radiography and acoustic emission for the thick welded joint testing

    International Nuclear Information System (INIS)

    The testing of the thick welded joints of the nuclear industry is carried out by radiography and ultrasonics on completion of welding. When a fault is found, its repair requires a sometimes deep cut down to the position of the fault, then filling in of the cut by hand welding with a coated electrode. This very costly operation also involves the risk of causing new defects when building up by hand. Listening to the acoustic emission during the welding has been considered in order to seek the possibility of detecting defects when they appear, or soon after. The industrial use of this method would make an instant repair of the defective areas possible at less cost and with greater reliability. The study presented concerns the comparison between the results of the various non-destructive testing methods: radiography, ultrasonics and acoustic emission, for a thick welded joint in which the defects have been brought about

  16. Electron Emission And Beam Generation Using Ferroelectric Cathodes (electron Beam Generation, Lead Lanthanum Zicronate Titanate, High Power Traveling Wave Tube Amplfier)

    CERN Document Server

    Flechtner, D D

    1999-01-01

    In 1989, researchers at CERN published the discovery of significant electron emission (1– 100 A/cm2) from Lead- Lanthanum-Zirconate-Titanate (PLZT). The publication of these results led to international interest in ferroelectric cathodes studies for use in pulsed power devices. At Cornell University in 1991, experiments with Lead-Zirconate-Titanate (PZT) compositions were begun to study the feasibility of using this ferroelectric material as a cathode in the electron gun section of High Power Traveling Wave Tube Amplifier Experiments. Current-voltage characteristics were documented for diode voltages ranging from 50– 500,000 V with anode cathode gaps of.5– 6 cm. A linear current-voltage relation was found for voltages less than 50 kV. For diode voltages ≥ 200 kV, a typical Child-Langmuir V3/2 dependence was observed...

  17. Stimulated emission pumping of NH in flames by using two-color resonant four-wave mixing

    Energy Technology Data Exchange (ETDEWEB)

    Radi, P.P.; Frey, H.M.; Mischler, B.; Tzannis, A.P.; Beaud, P.; Gerber, T. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    In this work we examine the analytical potential of two-color resonant four-wave mixing for the determination and characterization of trace elements in a combustion environment. Experimental results for NH in flames at atmospheric pressure are presented. The selectivity of the technique is used to simplify the Q-branch region of the (0-0)A{sup 3}{Pi}-X{sup 3}{Sigma} vibronic transition of NH. In addition, we demonstrate that the technique is sensitive to state changing collisions. (author) 2 figs., 5 refs.

  18. "Spectral Implementation" for creating a labeled pseudo-pure state and the Bernstein-Vazirani's algorithm in a four-qubit nuclear magnetic resonance quantum processor

    OpenAIRE

    Peng, Xinhua; Zhu, Xiwen; Fang, Ximing; Feng, Mang; Liu, Maili; Gao, Kelin

    2002-01-01

    A quantum circuit is introducted to describe the preparation of a labeled pseudo-pure state by mutiplet-component excitation scheme which has been experimentally implemented on a 4-qubit nuclear magnetic resonance quantum processor. Meanwhile, we theoretically analyze and numerically inverstigate the low-power selective single-pulse implementation of a controlled-rotation gate, which manifests its validity in our experiment. Based on the labeled pseudo-pure state prepared, a 3-qubit Bernstein...

  19. Mass-Energy and Momentum Extraction by Gravitational Wave Emission in the Merger of Two Colliding Black Holes: The Non-Head-On Case

    CERN Document Server

    Aranha, R F; Tonini, E V

    2011-01-01

    We examine numerically the post-merger regime of two Schwarzschild black holes in non head-on collision. Our treatment is made in the realm of non-axisymmetric Robinson-Trautman spacetimes which are appropriate for the description of the system. Characteristic initial data for the system are constructed and the Robinson-Trautman equation is integrated using a numerical code based on the Galerkin spectral method. The collision is planar, restricted to the plane determined by the directions of the two initial colliding black holes, with the net momentum fluxes of gravitational waves confined to this plane. We evaluate the efficiency of mass-energy extraction, the total energy and momentum carried out by gravitational waves and the momentum distribution of the remnant black hole. Our analysis is based on the Bondi-Sachs four momentum conservation laws. Head-on collisions and orthogonal collisions constitute, respectively, upper and lower bounds to the power emission and to the efficiency of mass-energy extractio...

  20. Terahertz Wave Emission from Intrinsic Josephson Junctions in Bi2Sr2CaCu2O8+δ

    International Nuclear Information System (INIS)

    We have studied the conditions for the THz radiation in many systems with different shapes and dimensions such as rectangles, squares, cylinders and (equilateral and isosceles including right-angled isosceles) triangles and rectangles with non-uniform width (asymmetric rectangles) fabricated from single crystals of Bi2Sr2CaCu2O8+δ, which are known as a typical intrinsic Josephson junction system. As a result two conditions have been deduced to be fulfilled: one is the ac-Josephson effect always working at each intrinsic Josephson junction. Another one is the standing wave formation of the THz waves excited inside the mesa due to the cavity resonance for the radiation. The former condition is always necessary for the radiation but the latter may have only the secondary role for the radiation because the Q-value of the resonance cavity in some cases seems to be quite low and of order of unity. Therefore, the radiation frequency can be controlled by the voltage effectively and widely varied by the ac-Josephson effect only. In addition, we show a new phenomenon observed at high current region and a comprehensive physical picture for the extraordinary THz radiation phenomenon is given.

  1. Non linear response of plasma ions in linear electrostatic waves

    International Nuclear Information System (INIS)

    We present experiments which test the applicability of the Hamiltonian single particle theory to wave-particle interactions. This theory describes the chaotic acceleration of plasmas ions by electrostatic waves. The Hamiltonian description gives predictions about the threshold, fast time scale, details of the distribution function and conservation of three integrals of the motion while some of the integrals have been broken by the overlap of resonances. Both electrostatic ion cyclotron and Bernstein waves are launched from antennae at the plasma boundary. Ion motions are observed by Laser Induced Fluorescence (LIF) and optical tagging. The linear response of the ion to the wave is distinguished from the chaotic response. Several predictions of the single particle theory are observed in the experiments. In addition, evidence of self-consistent effects have been observed. (author) 14 figs., 22 refs

  2. Suppression of Weibel Instabilities by High Harmonic Electron Bernstein Modes in Advanced Fast Ignition Laser Fusion Pellets

    Science.gov (United States)

    Stefan, V.

    2006-10-01

    A novel mechanism for the suppression of Weibel instabilities in the core of advanced fast ignition pellets is addressed. The propagation of generated suprathermal electron beam toward the core may lead to the appearance of colossal (˜10MG), small scale (L˜c/φpe, c---velocity of light, φpe---local electron plasma frequency) magnetic fields. The suppression synergy of high harmonic electron Bernstein, (EB), modes and Weibel modes, (WB), in the cone-attached laser fusion pellets is based on nonlinear mode-mode coupling. EB modes are excited by ignition, a cone guided, or implosion laser beams. High harmonic EB modes easily propagate to the core of the pellet whereby they nonlinearly interact with, and suppress, the WB. The suppression synergy is maximized at the simultaneous action of ignition and implosion lasers. E. S. Weibel, Phys. Rev. Lett., 2,83 (1959) in the core of advanced fast ignition pellets M. Tabak, J. Hammer, M.E. Glinsky, W.L. Kruer, S. C. Wilks, J. Woodworth, E. M. Campbell, and M.D. Perry, Phys. Plasmas 1 (5), 1626 (1994). V. Stefan, (a) Quasi-Stationary B-Fields due to Weibel Instability in FI Laser Fusion Pellets; (b) Pellet Core Heating Via High Harmonic EB Modes in FI Laser Fusion. 35th Annual A.A.C, 2005,

  3. Development of Superconducting Submillimeter-Wave Limb-Emission Sounder (JEM/SMILES) Aboard the International Space Station

    Science.gov (United States)

    Manabe, Takeshi

    2002-06-01

    In recent years, stratospheric ozone depletion is one of the most significant global environmental issues. it is well known that stratospheric trace gases, which include chlorine oxides and bromine oxides, play a crucial role in the process of stratospheric ozone destruction. Although the abundances of these trace gases are as low as in the order of parts par billion or less, they are quite efficient to destroy stratospheric ozone by catalytic reactions. In order to establish the techniques to monitor stratospheric Ozone and Ozone depleting molecules, CRL (Communications Research Laboratory and NASDA are collaborating to develop Superconducting Submillimeter-Limb Emission Sounder (JEM/SMILES) to be aboard the Japanese Experiment Module (JEM) of the International Space Station. In this paper, the outline of the JEM/SMILES project and the payload instrument is introduced.

  4. Stability of nonspinning effective-one-body model in approximating two-body dynamics and gravitational-wave emission

    CERN Document Server

    Pan, Yi; Taracchini, Andrea; Boyle, Michael; Kidder, Lawrence E; Mroue, Abdul H; Pfeiffer, Harald P; Scheel, Mark A; Szilagyi, Bela; Zenginoglu, Anil

    2013-01-01

    The detection of gravitational waves and the extraction of physical information from them requires the prediction of accurate waveforms to be used in template banks. For that purpose, the accuracy of effective-one-body (EOB) waveforms has been improved over the last years by calibrating them to numerical-relativity (NR) waveforms. So far, the calibration has employed a handful of NR waveforms with a total length of ~30 cycles, the length being limited by the computational cost of NR simulations. Here we address the outstanding problem of the stability of the EOB calibration with respect to the length of NR waveforms. Performing calibration studies against NR waveforms of nonspinning black-hole binaries with mass ratios 1, 1.5, 5, and 8, and with a total length of ~60 cycles, we find that EOB waveforms calibrated against either 30 or 60 cycles will be indistinguishable by the advanced detectors LIGO and Virgo when the signal-to-noise ratio (SNR) is below 110. When extrapolating to a very large number of cycles...

  5. Gravitational Wave transient signal emission via Ekman Pumping in Neutron Stars during post-glitch relaxation phase

    CERN Document Server

    Singh, Avneet

    2016-01-01

    Glitches in the rotational frequency of a spinning neutron star could be promising sources of gravitational wave signals lasting between a few {\\mu}s to a few weeks. The emitted signals and their properties depend upon the internal properties of the neutron star. In stellar models that assume a super-fluid core for the neutron star, the most important physical properties are the viscosity of the super-fluid, the stratification of flow in the equilibrium state and the adiabatic sound speed. Such models were previously studied by van Eysden and Melatos (2008) and Bennett et al. (2010) following simple assumptions on all contributing factors, in which the post-glitch relaxation phase could be driven by the well-known process of 'Ekman pumping'. We explore the hydrodynamic properties of the flow of super-fluid during this phase following more relaxed assumptions on the stratification of flow and/or the pressure-density gradients within the neutron star than previously studied. We calculate the time-scales of dura...

  6. The formation of eccentric compact binary inspirals and the role of gravitational wave emission in binary-single stellar encounters

    Energy Technology Data Exchange (ETDEWEB)

    Samsing, Johan [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); MacLeod, Morgan; Ramirez-Ruiz, Enrico [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    2014-03-20

    The inspiral and merger of eccentric binaries leads to gravitational waveforms distinct from those generated by circularly merging binaries. Dynamical environments can assemble binaries with high eccentricity and peak frequencies within the LIGO band. In this paper, we study binary-single stellar scatterings occurring in dense stellar systems as a source of eccentrically inspiraling binaries. Many interactions between compact binaries and single objects are characterized by chaotic resonances in which the binary-single system undergoes many exchanges before reaching a final state. During these chaotic resonances, a pair of objects has a non-negligible probability of experiencing a very close passage. Significant orbital energy and angular momentum are carried away from the system by gravitational wave (GW) radiation in these close passages, and in some cases this implies an inspiral time shorter than the orbital period of the bound third body. We derive the cross section for such dynamical inspiral outcomes through analytical arguments and through numerical scattering experiments including GW losses. We show that the cross section for dynamical inspirals grows with increasing target binary semi-major axis a and that for equal-mass binaries it scales as a {sup 2/7}. Thus, we expect wide target binaries to predominantly contribute to the production of these relativistic outcomes. We estimate that eccentric inspirals account for approximately 1% of dynamically assembled non-eccentric merging binaries. While these events are rare, we show that binary-single scatterings are a more effective formation channel than single-single captures for the production of eccentrically inspiraling binaries, even given modest binary fractions.

  7. Ion cyclotron emission due to the newly-born fusion products induced fast Alfven wave radiative instabilities in tokamaks

    International Nuclear Information System (INIS)

    The velocity distribution functions of the newly born (t = 0) charged fusion products of tokamak discharges can be approximated by a monoenergetic ring distribution with a finite vparallel such that vperpendicular ∼ vparallel ∼ vj where (MjVj2/2) = Ej, the directed birth energy of the charged fusion product species j of mass Mj. As the time t progresses these distribution functions will evolve into a Gaussian in velocity with thermal spreadings given by the perpendicular and parallel temperatures Tperpendicularj(t) = Tparallelj(t) with Tj(t) increasing as t increases and finally reaches an isotropic saturation value of Tperpendicularj(t ∼ τj) = Tparallelj(t ∼ τj) = Tj(t ∼ τj) ∼ [MjTdEj/(Mj + M)]1/2, where Td is the temperature of the background deuterium plasma ions, M is the mass of a triton or a neutron for j = protons and alpha particles, respectively, and τj ∼ τsj/4 is the thermalization time of the fusion product species j in the background deuterium plasma and τsj is the slowing-down time. For times t of the order of τj their distributions can be approximated by a Gaussian in their total energy. Then for times t ≥ τsj the velocity distributions of these fusion products will relax towards their appropriate slowing-down distributions. Here the authors will examine the radiative stability of all these distributions. The ion cyclotron emission from energetic ion produced by fusion reactions or neutral beam injection promises to be a useful diagnostic tool

  8. Recontextualização da simulação clínica em enfermagem baseada em Basil Bernstein: semiologia da prática pedagógica Recontextualización de la simulación de enfermería clínica basada en Basil Bernstein: la semiología de la práctica pedagógica Recontextualization of Nursing clinical simulation based on Basil Bernstein: semiology of pedagogical practice

    Directory of Open Access Journals (Sweden)

    Mateus Casanova dos Santos

    2010-12-01

    Full Text Available O presente artigo é um estudo de caso investigativo de caráter participante e descritivo, a partir da vivência pedagógica no disparador de aprendizagem Simulação em Enfermagem, do segundo semestre do primeiro ciclo da graduação da Faculdade de Enfermagem (FEn da Universidade Federal de Pelotas (UFPel, onde se desenvolve a simulação clínica de semiologia e semiotécnica em Enfermagem. O objetivo é estudar a recontextualização da prática pedagógica da Simulação com base em teorizações do sociólogo da educação Basil Bernstein, contribuindo para o processo de aperfeiçoamento do planejamento de ensino e, especialmente, da avaliação deste disparador de aprendizagem. A partir das reflexões deste estudo, observa-se a teorização de Bernstein como uma potente ferramenta semiológica das práticas pedagógicas, a qual contribui para o planejamento e análise do dispositivo pedagógico curricular.Este artículo es un caso de estudio de carácter descriptivo y de investigación participante, desde la experiencia educativa de aprendizaje en el gatillo Simulación en Enfermería, de la segunda mitad del primer ciclo de la Escuela Enfermería (FEN de la Universidade Federal de Pelotas (UFPel donde se desarrolla la simulación de la semiología clínica y la semiótica en Enfermería. El objetivo es estudiar la recontextualización de la práctica pedagógica de teorías basadas en la simulación del sociólogo de la educación Basil Bernstein, contribuyendo al proceso de mejora de la educación, planificación y aprendizaje, especialmente la evaluación de gatillo. De las reflexiones de este estudio, existe la teoría de Bernstein como una poderosa herramienta de semiótica prácticas pedagógicas, lo que contribuye a la planificación y el análisis de dispositivos educativos curriculares.This article is a case study of investigative and descriptive participant character, from the educational experience of learning in the trigger

  9. Ion cyclotron emission due to the newly-born fusion products induced fast Alfven wave radiative instabilities in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Arunasalam, V.

    1995-08-01

    The velocity distribution functions of the newly born (t = 0) charged fusion products of tokamak discharges can be approximated by a monoenergetic ring distribution with a finite v{sub {parallel}} such that v{sub {perpendicular}} {approx} v{sub {parallel}} {approx} v{sub j} where (M{sub j}V{sub j}{sup 2}/2) = E{sub j}, the directed birth energy of the charged fusion product species j of mass M{sub j}. As the time t progresses these distribution functions will evolve into a Gaussian in velocity with thermal spreadings given by the perpendicular and parallel temperatures T{sub {perpendicular}j}(t) = T{sub {parallel}j}(t) with T{sub j}(t) increasing as t increases and finally reaches an isotropic saturation value of T{sub {perpendicular}j}(t {approx} {tau}{sub j}) = T{sub {parallel}j}(t {approx} {tau}{sub j}) = T{sub j}(t {approx} {tau}{sub j}) {approx} [M{sub j}T{sub d}E{sub j}/(M{sub j} + M)]{sup 1/2}, where T{sub d} is the temperature of the background deuterium plasma ions, M is the mass of a triton or a neutron for j = protons and alpha particles, respectively, and {tau}{sub j} {approx} {tau}{sub sj}/4 is the thermalization time of the fusion product species j in the background deuterium plasma and {tau}{sub sj} is the slowing-down time. For times t of the order of {tau}{sub j} their distributions can be approximated by a Gaussian in their total energy. Then for times t {ge} {tau}{sub sj} the velocity distributions of these fusion products will relax towards their appropriate slowing-down distributions. Here the authors will examine the radiative stability of all these distributions. The ion cyclotron emission from energetic ion produced by fusion reactions or neutral beam injection promises to be a useful diagnostic tool.

  10. Diurnal ozone variations in the stratosphere revealed in observations from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on board the International Space Station (ISS)

    Science.gov (United States)

    Sakazaki, Takatoshi; Fujiwara, Masatomo; Mitsuda, Chihiro; Imai, Koji; Manago, Naohiro; Naito, Yoko; Nakamura, Tetsu; Akiyoshi, Hideharu; Kinnison, Douglas; Sano, Takuki; Suzuki, Makoto; Shiotani, Masato

    2013-04-01

    Considerable uncertainties remain in the global pattern of diurnal variation in stratospheric ozone, particularly lower to middle stratospheric ozone, which is the principal contributor to total column ozone. The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) attached to the Japanese Experiment Module (JEM) on board the International Space Station (ISS) was developed to gather high-quality global measurements of stratospheric ozone at various local times, with the aid of superconducting mixers cooled to 4K by a compact mechanical cooler. Using the SMILES dataset, as well as data from nudged chemistry-climate models (MIROC3.2-CTM and SD-WACCM), we show that the SMILES observational data have revealed the global pattern of diurnal ozone variations throughout the stratosphere. We also found that these variations can be explained by both photochemistry and dynamics. The peak-to-peak difference in the stratospheric ozone mixing ratio (total column ozone) reached 8% (1%) over the course of a day. This variation needs to be considered when merging ozone data from different satellite measurements and even from measurements made using one specific instrument at different local times.

  11. Development of a superconducting submillimeter-wave limb emission sounder (SMILES) on the Japanese Experiment Module (JEM) of the International Space Station (ISS)

    Science.gov (United States)

    Ikeda, Naomi; Inatani, Junji; Iida, Yukiei; Masuko, Harunobu; Manabe, Takeshi; Ochiai, Satoshi; Irimajiri, Yoshihisa; Seta, Masumichi; Shi, Sheng-Cai; Noguchi, Takashi

    1998-11-01

    NASDA and CRL are planning to develop a spaceborne SMILES, which is to be installed in the Exposed Facility (EF) on the JEM of the ISS. By observing gases such as ClO, HCl, NO, N2O, HO2 and BrO in the stratosphere, JEM/SMILES can trace the chemical reactions concerning the ozone depletion and climate change. Global distribution of those gases will be mapped with a height resolution of about 2 km. JEM/SMILES receives low-intensity signals from those gases with highly sensitive SIS (Superconductor-Insulator-Superconductor) mixers at 640 GHz, which are cooled to 4.2 K by a space-qualified mechanical cooler. The mission target is to demonstrate the effectiveness of the submillimeter-wave limb emission sounding and to establish space applicability of the low-noise SIS mixers and a mechanical 4-K cooler. JEM/SMILES is expected to be launched in 2003, and the experiments will last a year or more.

  12. Making use of x-ray optical effects in photoelectron-, Auger electron-, and x-ray emission spectroscopies: Total reflection, standing-wave excitation, and resonant effects

    International Nuclear Information System (INIS)

    We present a general theoretical methodology and related open-access computer program for carrying out the calculation of photoelectron, Auger electron, and x-ray emission intensities in the presence of several x-ray optical effects, including total reflection at grazing incidence, excitation with standing-waves produced by reflection from synthetic multilayers and at core-level resonance conditions, and the use of variable polarization to produce magnetic circular dichroism. Calculations illustrating all of these effects are presented, including in some cases comparisons to experimental results. Sample types include both semi-infinite flat surfaces and arbitrary multilayer configurations, with interdiffusion/roughness at their interfaces. These x-ray optical effects can significantly alter observed photoelectron, Auger, and x-ray intensities, and in fact lead to several generally useful techniques for enhancing surface and buried-layer sensitivity, including layer-resolved densities of states and depth profiles of element-specific magnetization. The computer program used in this study should thus be useful for a broad range of studies in which x-ray optical effects are involved or are to be exploited in next-generation surface and interface studies of nanoscale systems.

  13. Propagation of a strong x-ray pulse: Pulse compression, stimulated Raman scattering, amplified spontaneous emission, lasing without inversion, and four-wave mixing

    International Nuclear Information System (INIS)

    We study the compression of strong x-ray pulses from x-ray free-electron lasers (XFELs) propagating through the resonant medium of atomic argon. The simulations are based on the three-level model with the frequency of the incident x-ray pulse tuned in the 2p3/2-4s resonance. The pulse propagation is accompanied by the self-seeded stimulated resonant Raman scattering (SRRS). The SRRS starts from two channels of amplified spontaneous emission (ASE), 4s-2p3/2 and 3s-2p3/2, which form the extensive ringing pattern and widen the power spectrum. The produced seed field triggers the Stokes ASE channel 3s-2p3/2. The population inversion is quenched for longer propagation distances where the ASE is followed by the lasing without inversion (LWI), which amplifies the Stokes component. Both ASE and LWI reshape the input pulse: The compressed front part of the pulse (up to 100 as) is followed by the long tail of the ringing and beating between the pump and Stokes frequencies. The pump pulse also generates weaker Stokes and anti-Stokes fields caused by four-wave mixing. These four spectral bands have fine structures caused by the dynamical Stark effect. A slowdown of the XFEL pulse up to 78% of the speed of light in vacuum is found because of a large nonlinear refractive index.

  14. Spectral asymmetries in ground-state grating and stimulated emission pumping configurations of two-color resonant four-wave-mixing spectroscopy

    International Nuclear Information System (INIS)

    The recent evolution toward resonant conditions of the two-color resonant four-wave-mixing (TC-RFWM) spectroscopy has been dictated by the high sensitivity required experimentally. While some models have been used in different contexts such as light pressure forces in strong polychromatic fields, magnetically assisted Sisyphus effect, or multiphoton resonances in Λ atoms, the existence in molecules of additional processes such as nonradiative transitions and rotational or vibrational dephasings requires the extension of previous models. For this reason, we give here a general description of the internal dynamics for a molecule undergoing two strong grating beams, acting either on two different transitions sharing a common level or on the same transition, and one weak probe beam to reproduce the ground-state grating and stimulated emission pumping configurations of TC-RFWM spectroscopy. By combining high spectral resolution and strong grating beams, we show that the TC-RFWM spectrum is very sensitive to the transition constants, dephasing constants, as well as to the transverse velocity of the molecules in the jet. The last case corresponding to a bichromatic field acting on a single transition is used to explain the origin of the line-shape asymmetry observed experimentally on jet-cooled molecules

  15. Harmonics Effect on Ion-Bulk Waves in CH Plasmas

    CERN Document Server

    Feng, Q S; Liu, Z J; Cao, L H; Xiao, C Z; Wang, Q; He, X T

    2016-01-01

    The harmonics effect on ion-bulk (IBk) waves has been researched by Vlasov simulation. The condition of excitation of a large-amplitude IBk waves is given to explain the phenomenon of strong short-wavelength electrostatic activity in solar wind. When $k$ is much lower than $k_{lor}/2$ ($k_{lor}$ is the wave number at loss-of-resonance point), the IBk waves will not be excited to a large amplitude, because a large part of energy will be spread to harmonics. The nature of nonlinear IBk waves in the condition of $kBernstein-Greene-Kruskal-like waves with harmonics superposition. Only when the wave number $k$ of IBk waves satisfies $k_{lor}/2\\lesssim k\\leq k_{lor}$, can a large-amplitude and mono-frequency IBk wave be excited. These results give a guidance for a novel scattering mechanism related to IBk waves in the field of laser plasma interaction.

  16. On a New Family of Trigonometric Summation Polynomials of Bernstein Type%关于一类新的Bernstein型三角求和多项式

    Institute of Scientific and Technical Information of China (English)

    袁学刚; 何甲兴

    2006-01-01

    A new family of trigonometric summation polynomials, Gn,r(f; θ), of Bernstein type is constructed. In contrast to other trigonometric summation polynomials, the convergence properties of the new polynomials are superior to others.It is proved that Gn,r(f; θ) converges to arbitrary continuous functions with period 2π uniformly on (-∞, +∞) as n →∞. In particular, Gn,r(f; θ) has the best convergence order, and its saturation order is 1/n2r+4.

  17. PIC Simulations of the Ion Flow Induced by Radio Frequency Waves in Ion Cyclotron Frequency Range

    International Nuclear Information System (INIS)

    Full text: PIC simulations have been conducted to study the nonlinear interactions of plasmas and radio frequency wave in the ion cyclotron frequency range. It is found that in the presence of the mode conversion from an electromagnetic wave into an electrostatic wave (ion Bernstein wave), the ions near the lower hybrid resonance can be heated by nonlinear Landau damping via the parametric decay. As a result, the ion velocity distribution in the poloidal direction becomes asymmetric near the lower hybrid resonance and an ion poloidal flow is thus produced. The flow directions are opposite on both sides of the lower hybrid resonance. The poloidal flow is mainly produced by the nonlinear Reynolds stress and the electromagnetic force of the incident wave in the radial direction rather than poloidal direction predicted by the existing theories. (author)

  18. Terahertz Emission Dependence on the Fundamental Optical Intensity in Generating Terahertz Waves from Two-Color Laser-Induced Gas Plasma

    Institute of Scientific and Technical Information of China (English)

    DAI Hou-Mei; LIU Jin-Song

    2011-01-01

    A transient photocurrent model is used to explain terahertz ermission from gas plasma irritated by two-color laser pulses,with one the second harmonic of the other.Taking multiple degrees of ionization into account,the gas ionization process at different laser intensities from 1014 W/cm2 to 1015 W/cm2 is discussed.The results show that when Iω ≥ 6 × 1014 W/cm2,double ionization plays an important role in producing electrons.The corresponding terahertz spectra and waveforms are calculated,showing that increasing laser intensity can broaden the spectra to high frequencies and enhance the terahertz field.A promising method for generating terahertz (THz) waves involves emission from laser induced gas plasmas,which was first introduced hy Hamster et al.[1,2] By focusing laser femtosecond pulses with intensity greater than the thresholl for ionization of the gas molecules,one can obtain significant plasma formation.The ionized electrons will then accelerate by the lapser ponderomotive force,thus an electromagnetic pulse at THz frcqucncies can be produced.Since then,other plasma-based THz generation scheines have been proposed.L(o)ffler et al.,[3,4] applied an external dc bias to the plasma region,leading to an approximately one order of magnitude increase in the THz field strength.%A transient photocurrent model is used to explain terahertz emission from gas plasma irritated by two-color laser pulses, with one the second harmonic of the other. Taking multiple degrees of iom'xntion into account, the gas ionizntion process at different laser intensities from 1014 W/cm2 to 1015 W/cm2 is discussed. The results show that when /w > 6 X 1014 W/cin2, double ionization plays an important role in producing electrons. The corresponding terahertz spectra and waveforms are calculated, showing that increasing laser intensity can broaden the spectra to high frequencies and enhance the terahertz Geld.

  19. Ion cyclotron emission by spontaneous emission

    Energy Technology Data Exchange (ETDEWEB)

    Da Costa, O. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Gresillon, D. [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises

    1994-07-01

    The goal of the study is to examine whether the spontaneous emission can account for ICE (ion cyclotron emission) experimental results, or part of them. A straightforward approach to plasma emission is chosen, investigating the near equilibrium wave radiation by gyrating ions, and thus building from the majority and fast fusion ions the plasma fluctuations and emission on the fast magnetoacoustic or compressional Alfven wave mode in the IC frequency range. Similarities with the ICE experiments are shown: the emission temperature in the presence of fast ions (even in a very small amount), the strong fast ion emission increase with the harmonic, the fine double-line splitting of each peak, the linear but not proportional increase of the peak width with the harmonic. 3 refs., 2 figs.

  20. Seismic Resonant Emission

    Science.gov (United States)

    Korneev, V. A.

    2007-12-01

    There are several classes of underground objects which can produce resonant emission after being hit by incident seismic waves. Those objects include tunnels, pipes, buried containers, ground-filled excavations, unexploded ordinances, fluid-filled fractures, mine shafts, and the like. Being high contrast scatterers, these objects are capable of generating strong scattered waves where primary PP, PS, SS waves carry away most of the energy which was brought by incident waves. For both high- and low- velocity objects the primary scattered waves have the same order of magnitude as incident waves. The main difference between these groups of objects is in later arrivals of multiple scattered waves. While high-velocity objects effectively radiate most of the energy soon after impact, the low-velocity objects trap some fraction of incident wave energy in the form of circumferential waves which propagate rotating along the interface between the object and the embedding medium. Circumferential waves include surface Rayleigh-type waves (propagating mostly in the embedding medium), Stoneley waves (propagating mostly in the fluid, if present), and Frantz waves (body waves trapped in the object because of its curvature). Strong impedance contrast ensures small radiation loss for circumferential waves and they slowly decay in amplitude while rotating inside/around the object. Some circumferential waves exist in the high-velocity objects but their amplitudes decay very fast because of strong radiation in outer medium. Most of the secondary (multiply reflected from an object's boundaries or multiply circled around the object) resonant-scattered energy radiates in the embedding medium as shear waves. The possibility of neglecting P- waves in late scattering arrivals simplifies imaging as is demonstrated for the field and modeled data of the example. Resonant emission phenomenon provides an effective tool for active monitoring for a number of applications such as tunnel detection

  1. Uvidet heruvima / Boris Bernstein

    Index Scriptorium Estoniae

    Bernštein, Boriss, 1924-

    2006-01-01

    Inglite kujundi loomisest euroopalike traditsioonide baasil. Inglite kujutamine Euroopa kunstis. Vaadeldud Jean Fouquet, Benozzo Gozzoli, Raffaeli, Luigi Bernini, Aleksandr Ivanovi, Alek Rapoporti töid

  2. Wave propagation and absorption near the electron-cyclotron layer in the 'THOR' device

    International Nuclear Information System (INIS)

    The wave propagation and absorption near the electron-cyclotron frequency in a plasma with parameters as expected in the THOR device are considered. Both the ordinary and extraordinary modes are found to be only weakly damped by cyclotron damping. The extraordinary mode launched from the inside of the torus is expected to be completely absorbed at the electron-cyclotron layer via the Bernstein mode generated by mode conversion at the upper-hybrid layer. This study is preliminary to the application of high frequency microwave radiation to plasma heating near the electron-cyclotron frequency in THOR

  3. Parametrically driven low-frequency waves in weakly inhomogeneous magnetized plasmas

    International Nuclear Information System (INIS)

    The linear dispersion relation governing the parametric interaction of a lower hybrid (or an electron plasma) pump wave with a weakly inhomogeneous current-carrying hot cylindrical plasma confined by a helical magnetic field is derived and solved numerically. The coupling parameter, frequency and growth rate of decay instabilities are calculated for a wide range of plasma parameters relevant to lower hybrid plasma heating experiments. It is found that in the outer plasma layer (20/ωsub(LH)0/ωsub(LH)<2) the short wavelength nonresonant quasimodes and hot ion Bernstein waves have relatively fast growth rates and small group velocities, and consequently they are considerably amplified in the pump wave field. These waves are strongly damped by electron Landau and ion cyclotron harmonic interaction. The presented theoretical results are in good qualitative agreement with current LH plasma heating experiments

  4. Experimental Studies of BGK Ion Waves

    Science.gov (United States)

    Skiff, F.; Noonan, W. A.; Case, A.; Bachet, G.; Doveil, F.

    2000-10-01

    Since the classic work of Bernstein, Green, and Kruskal, it has been known that plasmas support a large class of propagating disturbances that are kinetic equilibria in the propagating frame. We present experimental studies of BGK ion equilibria in singly ionized Argon plasma in two contexts. The first context is the formation of an ion phase-space hole behind a weak electrostatic shock in unmagnetized plasma. The approach toward BGK equilibrium where the contours of the ion distribution function tend to align with curves of constant particle energy in the propagating frame - is observed and the structure is shown to be a solution of the kinetic equation. The second context is a low amplitude time-periodic structure that interacts primarily with ions near wave-particle resonance in magnetized plasma. There exist theoretical predictions of nonlinear waves at very low amplitude. The existence of low amplitude nonlinear waves complicates the formulation of a complete linear description. In each context, laser induced florescence is used to measure the perturbation of the ion distribution and to determine the associated electrostatic electric field.

  5. Wave particle interactions in the high-altitude polar cusp: a Cluster case study

    Directory of Open Access Journals (Sweden)

    B. Grison

    2005-12-01

    Full Text Available On 23 March 2002, the four Cluster spacecraft crossed in close configuration (~100 km separation the high-altitude (10 RE cusp region. During a large part of the crossing, the STAFF and EFW instruments have detected strong electromagnetic wave activity at low frequencies, especially when intense field-aligned proton fluxes were detected by the CIS/HIA instrument. In all likelihood, such fluxes correspond to newly-reconnected field lines. A focus on one of these ion injection periods highlights the interaction between waves and protons. The wave activity has been investigated using the k-filtering technique. Experimental dispersion relations have been built in the plasma frame for the two most energetic wave modes. Results show that kinetic Alfvén waves dominate the electromagnetic wave spectrum up to 1 Hz (in the spacecraft frame. Above 0.8 Hz, intense Bernstein waves are also observed. The close simultaneity observed between the wave and particle events is discussed as an evidence for local wave generation. A mechanism based on current instabilities is consistent with the observations of the kinetic Alfvén waves. A weak ion heating along the recently-opened field lines is also suggested from the examination of the ion distribution functions. During an injection event, a large plasma convection motion, indicative of a reconnection site location, is shown to be consistent with the velocity perturbation induced by the large-scale Alfvén wave simultaneously detected.

  6. MHD waves in sunspots

    CERN Document Server

    Sych, Robert

    2015-01-01

    The review addresses the spatial frequency morphology of sources of sunspot oscillations and waves, including their localization, size, oscillation periods, height localization with the mechanism of cut-off frequency that forms the observed emission variability. Dynamic of sunspot wave processes, provides the information about the structure of wave fronts and their time variations, investigates the oscillation frequency transformation depending on the wave energy is shown. The initializing solar flares caused by trigger agents like magnetoacoustic waves, accelerated particle beams, and shocks are discussed. Special attention is paid to the relation between the flare reconnection periodic initialization and the dynamics of sunspot slow magnetoacoustic waves. A short review of theoretical models of sunspot oscillations is provided.

  7. Verification of particle simulation of radio frequency waves in fusion plasmas

    International Nuclear Information System (INIS)

    Radio frequency (RF) waves can provide heating, current and flow drive, as well as instability control for steady state operations of fusion experiments. A particle simulation model has been developed in this work to provide a first-principles tool for studying the RF nonlinear interactions with plasmas. In this model, ions are considered as fully kinetic particles using the Vlasov equation and electrons are treated as guiding centers using the drift kinetic equation. This model has been implemented in a global gyrokinetic toroidal code using real electron-to-ion mass ratio. To verify the model, linear simulations of ion plasma oscillation, ion Bernstein wave, and lower hybrid wave are carried out in cylindrical geometry and found to agree well with analytic predictions

  8. Demonstration of superconducting sub-millimeter-wave limb emission sounder (SMILES) for observing trace gases in the middle atmosphere using the exposed facility of the Japanese experimental module (JEM) of the international space station

    Science.gov (United States)

    Masuko, Harunobu; Manabe, Takeshi; Seta, Masumichi; Kasai, Yasuko; Ochiai, Satoshi; Irimajiri, Yoshihisa; Inatani, Junji; Ikeda, Naomi; Nishibori, Toshiyuki; Iida, Yukiei; Fujii, Yasunori

    1999-01-01

    The sub-millimeter wavelength region is advantageous for high-precision observations of trace species in the stratosphere. A Superconducting Sub-Millimeter-wave Limb Emission Sounder (SMILES) is scheduled to demonstrate the measurements of extremely faint sub-millimeter-wave emissions of the atmospheric trace gases on the Exposed Facility (EF) of the Japanese Experimental Module (JEM) of the International Space Station in 2003. The applications of superconductivity and mechanical 4K-refrigerator in space will be demonstrated in the experiment. JEM/SMILES obtains the diurnal and seasonal variability in the global three-dimensional distributions of the stratospheric trace gases for quantitative understanding of the stratospheric ozone depletion and its effect on the climate change with respect to the relationships among chemical reaction processes and their relationships with atmospheric dynamics. JEM/SMILES utilizes the 640GHz band to measure the vertical profiles of trace gases involved in the stratospheric ozone depletion such as chlorine monoxide (CLO), bromine monoxide (BrO), etc., along with atmospheric temperature. JEM/SMILES employs Superconductor-Insulator-Superconductor (SIS) mixers to improve measurement precision and spatial resolution, thereby enabling us to quantitatively understand the interactive processes between chemistry and dynamics.

  9. Newly Discovered Parametric Instabilities Excited by High Power Radio Waves in the Ionosphere

    Science.gov (United States)

    Bernhardt, Paul

    2010-11-01

    A powerful electromagnetic wave can decay into a large number of low frequency electrostatic waves and a scattered electromagnetic wave by generalized stimulated Brillouin scatter (GSBS). The generalization occurs in the F-layer ionosphere because of the presence of the magnetic field supporting a large number of plasma waves not present in an unmagnetized plasma. Stimulated Brillouin scatter excites the ion acoustic mode. In addition, GSBS can excite slow MHD, Alfven, fast MHD, ion cyclotron, whistler, lower hybrid, ion Bernstein waves. The first detection of this process during ionospheric modification with high power radio waves was demonstrated using the HAARP transmitter in Alaska in 2009. Subsequent experiments have provided additional verification of the GSBS process with quantitative measurements of the scattered electromagnetic waves with low frequency offsets from the pump wave. Relative to ground-based laboratory experiments with laser plasma interactions, the ionospheric HF wave interactions experiments are more completely diagnosed into terms of understanding the basic decay process of the magnetized plasma. Applications of the GSBS observations included remote sensing of the plasma state and launching propagating wave modes.

  10. Survey of Coherent Approximately 1 Hz Waves in Mercury's Inner Magnetosphere from MESSENGER Observations

    Science.gov (United States)

    Boardsen, Scott A.; Slavin, James A.; Anderson, Brian J.; Korth, Haje; Schriver, David; Solomon, Sean C.

    2012-01-01

    We summarize observations by the MESSENGER spacecraft of highly coherent waves at frequencies between 0.4 and 5 Hz in Mercury's inner magnetosphere. This survey covers the time period from 24 March to 25 September 2011, or 2.1 Mercury years. These waves typically exhibit banded harmonic structure that drifts in frequency as the spacecraft traverses the magnetic equator. The waves are seen at all magnetic local times, but their observed rate of occurrence is much less on the dayside, at least in part the result of MESSENGER's orbit. On the nightside, on average, wave power is maximum near the equator and decreases with increasing magnetic latitude, consistent with an equatorial source. When the spacecraft traverses the plasma sheet during its equatorial crossings, wave power is a factor of 2 larger than for equatorial crossings that do not cross the plasma sheet. The waves are highly transverse at large magnetic latitudes but are more compressional near the equator. However, at the equator the transverse component of these waves increases relative to the compressional component as the degree of polarization decreases. Also, there is a substantial minority of events that are transverse at all magnetic latitudes, including the equator. A few of these latter events could be interpreted as ion cyclotron waves. In general, the waves tend to be strongly linear and characterized by values of the ellipticity less than 0.3 and wave-normal angles peaked near 90 deg. Their maxima in wave power at the equator coupled with their narrow-band character suggests that these waves might be generated locally in loss cone plasma characterized by high values of the ratio beta of plasma pressure to magnetic pressure. Presumably both electromagnetic ion cyclotron waves and electromagnetic ion Bernstein waves can be generated by ion loss cone distributions. If proton beta decreases with increasing magnetic latitude along a field line, then electromagnetic ion Bernstein waves are predicted

  11. Production of over-dense plasmas by launching 2.45 GHz electron cyclotron waves in a helical device

    International Nuclear Information System (INIS)

    For production of low temperature plasmas with low collisionality, 2.45 GHz microwave power up to 20 kW is injected perpendicularly to the toroidal field at very low toroidal field Bt t = 0.0613 T, the maximum electron density reaches three times the O-mode cutoff density and the measured power deposition is concentrated in the plasma core region beyond the Left-hand cutoff layer. It clearly suggests that this over-dense plasma is produced and heated by electron Bernstein waves converted from the launched X-mode in the peripheral region with steep density gradient. (authors)

  12. Modeling of the propagation and reception of elastic waves emitted by a crack under stress. Application to the simulation of non-destructive testing by acoustic emission

    International Nuclear Information System (INIS)

    AE Non-destructive testing is used in many fields such as nuclear energy, oil and gas, civil engineering or mechanical engineering to check the integrity of structures under stress. Depending on the ratio of structure thickness to wavelength, the energy released by a crack under stress can propagate either as guided waves (in thin structures) or as Rayleigh wave (in thick structures). The analysis of signals resulting from this ultrasonic 'passive' method is particularly difficult due to the complexity of typically measured signals. The objective of this thesis is to develop models to enable the simulation of AE testing experiments in the case of thick or thin structure. The developed models rely on the coupling between an AE source model, wave propagation models and an AE Sensor model. In the case of thick structures two 2D models (for plane and cylindrical surfaces) and a 3D model (for plane surface) have been developed to predict the signal corresponding to the Rayleigh wave emitted by a crack under stress. In the case of thin structures, a 2D model has been developed to predict the signal corresponding to the guided modes emitted by a crack under stress. Several parametric studies have been conducted to determine the influence of the different model input data on the AE signals and thus help to interpret AE testing results. (author)

  13. A note on the drift waves in the presence of electrons added by meteors by ablation phenomena or by thermionic emissions

    Indian Academy of Sciences (India)

    V H Kulkarni; Shobha Kadam

    2012-07-01

    The role of added electrons on the drift dissipative instability in a nonuniform collisional plasma is analysed. We observe the presence of a drift wave that depends entirely on the added electrons through the collision frequency coupling and there is an additional damping. The present study is applied to the density irregularities caused by meteor ionization in the ionosphere.

  14. Unexpected waves

    Science.gov (United States)

    Gemmrich, J.; Garrett, C.

    2009-04-01

    Rogue waves have received considerable scientific attention in recent years. They are commonly defined as waves with height H ≥ 2.2Hs, where Hs is the significant wave height (typically estimated from records that are several tens of minutes long). This definition of rogue waves is solely based on the wave height. We suggest that the "unexpectedness" of large waves is also of great concern to mariners and beachcombers, and define "unexpected waves" as waves being twice as large as any of the preceding 30 waves. Our simulations suggest that, even in a Gaussian sea, unexpected waves might be as common as rogue waves occurring within a longer wave group. The return period of unexpected waves decreases if modifications of the wave shape due to phase locked second harmonics are allowed for. In particular, shallow water effects significantly increase the probability of occurrence of unexpected waves. We analyze historical Canadian wave buoy records from the Pacific and Atlantic in terms of unexpected waves, and find our simulations to be in agreement with the occurrence rates of unexpected waves obtained from these records. This agreement suggests that extreme waves in the ocean occur largely due to linear superposition

  15. Electromagnetic Waves

    DEFF Research Database (Denmark)

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis...

  16. Multicomponent kinetic simulation of Bernstein-Greene-Kruskal modes associated with ion acoustic and dust-ion acoustic excitations in electron-ion and dusty plasmas

    Science.gov (United States)

    Hosseini Jenab, S. M.; Kourakis, I.

    2014-04-01

    A series of numerical simulations based on a recurrence-free Vlasov kinetic algorithm presented earlier [Abbasi et al., Phys. Rev. E 84, 036702 (2011)] are reported. Electron-ion plasmas and three-component (electron-ion-dust) dusty, or complex, plasmas are considered, via independent simulations. Considering all plasma components modeled through a kinetic approach, the nonlinear behavior of ionic scale acoustic excitations is investigated. The focus is on Bernstein-Greene-Kruskal (BGK) modes generated during the simulations. In particular, we aim at investigating the parametric dependence of the characteristics of BGK structures, namely of their time periodicity (τtrap) and their amplitude, on the electron-to-ion temperature ratio and on the dust concentration. In electron-ion plasma, an exponential relation between τtrap and the amplitude of BGK modes and the electron-to-ion temperature ratio is observed. It is argued that both characteristics, namely, the periodicity τtrap and amplitude, are also related to the size of the phase-space vortex which is associated with BGK mode creation. In dusty plasmas, BGK modes characteristics appear to depend on the dust particle density linearly.

  17. Influence of power line harmonic radiation on the VLF wave activity in the upper ionosphere: Is it capable to trigger new emissions?

    Czech Academy of Sciences Publication Activity Database

    Němec, František; Parrot, M.; Santolík, Ondřej

    2010-01-01

    Roč. 115, - (2010), A11301/1-A11301/9. ISSN 0148-0227 R&D Projects: GA ČR GA205/09/1253; GA MŠk ME09107 Grant ostatní: MŠMT(CZ) MSM0021620860 Institutional research plan: CEZ:AV0Z30420517 Keywords : PLHR events * triggered emissions * DEMETER satellite Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.303, year: 2010

  18. Extreme ultra-violet burst, particle heating, and whistler wave emission in fast magnetic reconnection induced by kink-driven Rayleigh-Taylor instability

    Science.gov (United States)

    Chai, Kil-Byoung; Zhai, Xiang; Bellan, Paul M.

    2016-03-01

    A spatially localized energetic extreme ultra-violet (EUV) burst is imaged at the presumed position of fast magnetic reconnection in a plasma jet produced by a coaxial helicity injection source; this EUV burst indicates strong localized electron heating. A circularly polarized high frequency magnetic field perturbation is simultaneously observed at some distance from the reconnection region indicating that the reconnection emits whistler waves and that Hall dynamics likely governs the reconnection. Spectroscopic measurement shows simultaneous fast ion heating. The electron heating is consistent with Ohmic dissipation, while the ion heating is consistent with ion trajectories becoming stochastic.

  19. Observations of large-amplitude electromagnetic waves and associated wave-particle interactions at the dipolarization front in the Earth's magnetotail: A case study

    Science.gov (United States)

    Huang, S. Y.; Yuan, Z. G.; Ni, B.; Zhou, M.; Fu, H. S.; Fu, S.; Deng, X. H.; Pang, Y.; Li, H. M.; Wang, D. D.; Li, H. M.; Yu, X. D.

    2015-07-01

    Broadband frequency waves around the dipolarization front (DF) are believed to play a crucial role in the particle dynamics. Using the Cluster observations, we report in this study large-amplitude electromagnetic waves with frequencies just above the ion cyclotron frequency at the DF in the near-Earth magnetotail region. The waves have very large amplitudes of magnetic and electric field fluctuations, up to ~2 nT and ~10 mV/m, respectively. The magnetic fluctuations are predominately along the ambient magnetic field (B0), while the electric fluctuations are primarily perpendicular to B0. The observed waves are highly oblique with a propagation angle of ~100° with respect to the ambient magnetic field, and are also linearly polarized. These features are consistent with the properties of the ion Bernstein wave mode in the high plasma β region, and also with the properties of current-driven ion cyclotron waves driven by the electromagnetic current-driven Alfven instability. We also discuss the possibility of wave-particle interactions at the DF.

  20. High harmonic fast waves in high beta plasmas

    International Nuclear Information System (INIS)

    High harmonic fast magnetosonic wave in high beta/high dielectric plasmas is investigated. including the finite-Larmor-radius effects. In this regime, due to the combination of group velocity slow down and the high beta enhancement, the electron absorption via electron Landau and electron magnetic pumping becomes significant enough that one can expect a strong (∼ 100%) single pass absorption. By controlling the wave spectrum, the prospect of some localized electron heating and current drive appears to be feasible in high beta low-aspect-ratio tokamak regimes. Inclusion of finite-Larmor-radius terms shows an accessibility limit in the high ion beta regime (βi = 50% for a deuterium plasma) due to mode-conversion into an ion Bernstein-wave-like mode while no beta limit is expected for electrons. With increasing ion beta, the ion damping can increase significantly particularly near the beta limits. The presence of energetic ion component expected during intense NBI and α-heating does not appear to modify the accessibility condition nor cause excessive wave absorption

  1. Full-wave modeling of the O-X mode conversion in the Pegasus Toroidal Experiment

    CERN Document Server

    Köhn, Alf; Bongard, Michael W; Gallian, Sara; Hinson, Edward T; Volpe, Francesco A

    2011-01-01

    The ordinary-extraordinary (O-X) mode conversion is modeled with the aid of a 2D full-wave code in the Pegasus Toroidal Experiment as a function of the launch angles. It is shown how the shape of the plasma density profile in front of the antenna can significantly influence the mode conversion efficiency and, thus, the generation of electron Bernstein waves (EBW). It is therefore desirable to control the density profile in front of the antenna for successful operation of an EBW heating and current drive system. On the other hand, the conversion efficiency is shown to be resilient to vertical displacements of the plasma as large as \\pm 10 cm.

  2. Full-wave modeling of the O-X mode conversion in the Pegasus toroidal experiment

    Energy Technology Data Exchange (ETDEWEB)

    Koehn, A. [Institut fuer Plasmaforschung, Universitaet Stuttgart, D-70569 (Germany); Jacquot, J. [IRFM, CEA, F-13108 Saint-Paul-lez-Durance (France); Bongard, M. W.; Hinson, E. T.; Volpe, F. A. [Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Gallian, S. [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2011-08-15

    The ordinary-extraordinary (O-X) mode conversion is modeled with the aid of a 2D full-wave code in the Pegasus toroidal experiment as a function of the launch angles. It is shown how the shape of the plasma density profile in front of the antenna can significantly influence the mode conversion efficiency and, thus, the generation of electron Bernstein waves (EBWs). It is therefore desirable to control the density profile in front of the antenna for successful operation of an EBW heating and current drive system. On the other hand, the conversion efficiency is shown to be resilient to vertical displacements of the plasma as large as {+-}10 cm.

  3. Full-wave modeling of the O-X mode conversion in the Pegasus toroidal experiment

    International Nuclear Information System (INIS)

    The ordinary-extraordinary (O-X) mode conversion is modeled with the aid of a 2D full-wave code in the Pegasus toroidal experiment as a function of the launch angles. It is shown how the shape of the plasma density profile in front of the antenna can significantly influence the mode conversion efficiency and, thus, the generation of electron Bernstein waves (EBWs). It is therefore desirable to control the density profile in front of the antenna for successful operation of an EBW heating and current drive system. On the other hand, the conversion efficiency is shown to be resilient to vertical displacements of the plasma as large as ±10 cm.

  4. Laser emission in Nd3+ doped barium–titanium–silicate microspheres under continuous and chopped wave pumping in a non-coupled pumping scheme

    International Nuclear Information System (INIS)

    Laser action using non-coupled excitation and detection of microspheres made of Nd3+ doped barium–titanium–silicate glass has been demonstrated and measured. The microspheres have also been successfully deposited over Si3N4 strip waveguides with a SiO2 separation layer, thus enabling the laser emission extraction onto a CMOS compatible photonic circuit. The dynamics of the lasing wavelength and intensity has been studied as a function of the pump power and interpreted in terms of thermal effects generated through non-radiative recombination of the excited ions. (paper)

  5. Laser emission in Nd3+ doped barium-titanium-silicate microspheres under continuous and chopped wave pumping in a non-coupled pumping scheme

    OpenAIRE

    Martín, L. L.; Navarro-Urrios, D.; Ferrarese-Lupi, F.; Pérez-Rodríguez, C.; Martín, I. R.; J. Montserrat; Domínguez, Carlos; Garrido, Blas; N. Capuj

    2013-01-01

    Laser action using non-coupled excitation and detection of microspheres made of Nd3+ doped barium-titanium-silicate glass has been demonstrated and measured. The microspheres have also been successfully deposited over Si3N4 strip waveguides with a SiO2 separation layer, thus enabling the laser emission extraction onto a CMOS compatible photonic circuit. The dynamics of the lasing wavelength and intensity has been studied as a function of the pump power and interpreted in terms of thermal effe...

  6. Laser emission in Nd3+ doped barium-titanium-silicate microspheres under continuous and chopped wave pumping in a non-coupled pumping scheme

    Science.gov (United States)

    Martín, L. L.; Navarro-Urrios, D.; Ferrarese-Lupi, F.; Pérez-Rodríguez, C.; Martín, I. R.; Montserrat, J.; Dominguez, C.; Garrido, B.; Capuj, N.

    2013-07-01

    Laser action using non-coupled excitation and detection of microspheres made of Nd3+ doped barium-titanium-silicate glass has been demonstrated and measured. The microspheres have also been successfully deposited over Si3N4 strip waveguides with a SiO2 separation layer, thus enabling the laser emission extraction onto a CMOS compatible photonic circuit. The dynamics of the lasing wavelength and intensity has been studied as a function of the pump power and interpreted in terms of thermal effects generated through non-radiative recombination of the excited ions.

  7. Importance of the wave function tail in computing the pre-emission probability for the halo neutron from 11 Be fusion with light and heavy targets

    International Nuclear Information System (INIS)

    In this work, an improved method for the estimation of the neutron pre-emission probability in a fusion process is given, taking into account a more realistic halo neutron distribution with an extreme long tail. It has been demonstrated that core and halo densities can be separated in: ρ(r) = ρc (r) + ρh (r). 11 Be, the only one neutron halo nucleus has two bound states, both of halo type, with one neutron separation energies 0.5 MeV and 0.2 MeV, respectively. The 2s1/2 state is the main component (77%) of the ground state of 11 Be. The density distribution of the halo neutron was determined by solving Schroedinger equation for a separation energy of Sn = - 0.504 MeV using a Woods-Saxon potential. The halo neutron is considered to be on 2s1/2 state. The root mean square radius of 10 Be is taken as 2.90 fm. All the following steps in our estimation are parameter free for the neutron pre-emission probability method. A sharp cut-off approach for the fusion process was used. After computing the volume distribution, we calculated the superficial distribution of the halo neutron on a surface which is perpendicular on the beam direction. The volume was divided in spherical shells with step equal to 0.1 fm in which we considered the probability distribution to be constant. These shells were projected on that surface. After that, the same method was applied for three energies: E1 near the Coulomb barrier, E2 near the energy of an expected experiment and E3 near that value when the compound nucleus explodes. The results are given in a Table. The pre-emission probability is dependent on target radius. For a smaller size target (12 C, Si), the probability is larger than for a large size target nucleus (209 Bi). All these results are thought as an upper limit for the neutron pre-emission probability, due to the fact that the applied model corresponds to a r.m.s. radius of 5.2 fm for 11 Be neutron halo. We want to thank M. Fukuda, I. Bulboaca and F. Carstoiu for help and

  8. Observation of Gravitational Waves

    Science.gov (United States)

    Gonzalez, Gabriela

    2016-06-01

    On September 14 2015, the two LIGO gravitational wave detectors in Hanford, Washington and Livingston, Louisiana registered a nearly simultaneous signal with time-frequency properties consistent with gravitational-wave emission by the merger of two massive compact objects. Further analysis of the signals by the LIGO Scientific Collaboration and Virgo Collaboration revealed that the gravitational waves detected by LIGO came from the merger of a binary black hole (BBH) system approximately 420 Mpc distant (z=0.09) with constituent masses of 36 and 29 M_sun. I will describe the details of the observation, the status of ground-based interferometric detectors, and prospects for future observations in the new era of gravitational wave astronomy.

  9. X-Ray Emission from an Asymmetric Blast Wave and a Massive White Dwarf in the Gamma Ray Emitting Nova V407 CYG

    Science.gov (United States)

    Nelson, Thomas; Donato, Davide; Mukai, Koji; Sokoloski, Jennifer; Chomiuk, Laura

    2012-01-01

    Classical nova events in symbiotic stars, although rare, offer a unique opportunity to probe the interaction between ejecta and a dense environment in stellar explosions. In this work, we use X-ray data obtained with Swift and Suzaku during the recent classical nova outburst in V407 Cyg to explore such an interaction. We find evidence of both equilibrium and non-equilibrium ionization plasmas at the time of peak X-ray brightness, indicating a strong asymmetry in the density of the emitting region. Comparing a simple model to the data, we find that the X-ray evolution is broadly consistent with nova ejecta driving a forward shock into the dense wind of the Mira companion. We detect a highly absorbed soft X-ray component in the spectrum during the first 50 days of the outburst that is consistent with supersoft emission from the nuclear burning white dwarf. The high temperature and short turn off time of this emission component, in addition to the observed breaks in the optical and UV lightcurves, indicate that the white dwarf in the binary is extremely massive. Finally, we explore the connections between the X-ray and GeV-ray evolution, and propose that the gamma ray turn-off is due to the stalling of the forward shock as the ejecta reach the red giant surface.

  10. Wave vertaisverkossa

    OpenAIRE

    Kankaanniemi, Marko

    2011-01-01

    Google Wave is a real-time communication and collaboration system introduced in 2009. The Wave system allows multiple users to view and modify hosted conversations called waves simultaneously. A wave conversation consists of a tree-like structure of messages. The messages can contain rich text, images and other attachments. Concurrency control is handled using a technique called operational transformation. It enables users to modify a wave simultaneously without acquiring any locks. Google ha...

  11. Measurement of density fluctuations on the JIPP T-II tokamak plasma by millimeter and sub-millimeter wave scattering

    International Nuclear Information System (INIS)

    Scattering experiments with a 2-mm microwave oscillator (E.I.O.) and a 337-μm HCN laser were performed to measure density fluctuations on the JIPP T-II/T-IIU tokamak in a wide range of the plasma density. It is found from the measurements of the frequency and wavenumber spectra of the instability that the density fluctuation shows characteristics of a turbulence which is originated in the instability of drift type. The dependence of the fluctuation level on the plasma parameters was investigated and compared with the scaling law of the energy confinement time of the plasma. The relation between the density fluctuation level and the confinement time was obtained. The fluctuation level decreases as the electron density is increased. The plasma temperature dependence of the density fluctuation was also investigated. During the rf heating in the ion-cyclotron range of frequency (ICRF) the increase in the density fluctuation level was observed in low-frequency and long-wavelength region. The temporal behavior of the density fluctuation was correlated with the MHD oscillation observed by magnetic probes. The excited wave during the ICRF heating experiment was studied by the HCN laser scattering. The frequency and wavenumber spectra of the excited wave observed during the heating are found to be consistent with the theoretically estimated wave dispersion of the ion Bernstein wave which is mode-converted from the fast wave in the vicinity of the ion-ion hybrid resonance layer. When the MHD activity grows and the plasma becomes unstable, the scattered signal from the ion Bernstein wave decreases, being accompanied with large pulsation. (author)

  12. Wave turbulence

    Science.gov (United States)

    Nazarenko, Sergey

    2015-07-01

    Wave turbulence is the statistical mechanics of random waves with a broadband spectrum interacting via non-linearity. To understand its difference from non-random well-tuned coherent waves, one could compare the sound of thunder to a piece of classical music. Wave turbulence is surprisingly common and important in a great variety of physical settings, starting with the most familiar ocean waves to waves at quantum scales or to much longer waves in astrophysics. We will provide a basic overview of the wave turbulence ideas, approaches and main results emphasising the physics of the phenomena and using qualitative descriptions avoiding, whenever possible, involved mathematical derivations. In particular, dimensional analysis will be used for obtaining the key scaling solutions in wave turbulence - Kolmogorov-Zakharov (KZ) spectra.

  13. Plasma waves

    CERN Document Server

    Swanson, DG

    1989-01-01

    Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th

  14. Radio frequency wave experiments on the MST reversed field pinch

    International Nuclear Information System (INIS)

    Experiments, simulations, and theory all indicate that the magnetic fluctuations responsible for the poor confinement in the reversed field pinch (RFP) can be controlled by altering the radial profile of the current density. The magnetic fluctuations in the RFP are due to resistive MHD instabilities caused by current profile peaking; thus confinement in the RFP is ultimately the result of a misalignment between inductively driven current profiles and the stable current profiles characteristic of the Taylor state. If a technique such as rf current drive can be developed to non-inductively sustain a Taylor state (a current profile linearly stable to all tearing modes), the confinement of the RFP and its potential as a reactor concept are likely to increase. Whether there is a self-consistent path from poor confinement to greatly improved confinement through current profile modification is an issue for future experiments to address if and only if near term experiments can demonstrate: (1) coupling to and the propagation of rf waves in RFP plasmas, (2) efficient current drive, and (3) control of the power deposition which will make it possible to control the current profile. In this paper, modeling results and experimental plans are presented for two rf experiments which have the potential of satisfying these three goals: high-nparallel lower hybrid (LH) waves and electron Bernstein waves (EBWs)

  15. Heat Waves

    Science.gov (United States)

    Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and spasms due ... that the body is having trouble with the heat. If a heat wave is predicted or happening… - ...

  16. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star.......Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star....

  17. Acoustic emission source modeling

    Czech Academy of Sciences Publication Activity Database

    Hora, Petr; Červená, Olga

    2010-01-01

    Roč. 4, č. 1 (2010), s. 25-36. ISSN 1802-680X R&D Projects: GA ČR GA101/09/1630 Institutional research plan: CEZ:AV0Z20760514 Keywords : acoustic emission source * wave propagation * FEM Subject RIV: BI - Acoustics

  18. Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Sørensen, H. C.;

    1998-01-01

    This paper concerns with the development of the wave energy converter (WEC) Wave Dragon. This WEC is based on the overtopping principle. An overview of the performed research done concerning the Wave Dragon over the past years is given, and the results of one of the more comprehensive studies......, concerning a hydraulic evaluation and optimisation of the geometry of the Wave Dragon, is presented. Furthermore, the plans for the future development projects are sketched....

  19. Wave Dragon

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter; Knapp, W.;

    2006-01-01

    Wave Dragon is a floating wave energy converter working by extracting energy principally by means of overtopping of waves into a reservoir. A 1:4.5 scale prototype has been sea tested for 20 months. This paper presents results from testing, experiences gained and developments made during this...

  20. Wave phenomena

    CERN Document Server

    Towne, Dudley H

    1988-01-01

    This excellent undergraduate-level text emphasizes optics and acoustics, covering inductive derivation of the equation for transverse waves on a string, acoustic plane waves, boundary-value problems, polarization, three-dimensional waves and more. With numerous problems (solutions for about half). ""The material is superbly chosen and brilliantly written"" - Physics Today. Problems. Appendices.

  1. Shell theorem for spontaneous emission

    DEFF Research Database (Denmark)

    Kristensen, Philip Trøst; Mortensen, Jakob Egeberg; Lodahl, Peter; Stobbe, Søren

    2013-01-01

    We investigate spontaneous emission from excitons beyond the point source dipole approximation and show how the symmetry of the exciton wave function plays a crucial role. We find that for spherically symmetric wave functions, the Purcell effect is independent of the wave function size and...... therefore is given exactly by the dipole approximation theory. This surprising result is a spontaneous emission counterpart to the shell theorems of classical mechanics and electrostatics and provides insights into the physics of mesoscopic emitters as well as great simplifications in practical calculations....

  2. Waves in pulsar winds

    CERN Document Server

    Kirk, J G

    2010-01-01

    The radio, optical, X-ray and gamma-ray nebulae that surround many pulsars are thought to arise from synchrotron and inverse Compton emission. The energy powering this emission, as well as the magnetic fields and relativistic particles, are supplied by a "wind" driven by the central object. The inner parts of the wind can be described using the equations of MHD, but these break down in the outer parts, when the density of charge carriers drops below a critical value. This paper reviews the wave properties of the inner part (striped wind), and uses a relativistic two-fluid model (cold electrons and positrons) to re-examine the nonlinear electromagnetic modes that propagate in the outer parts. It is shown that in a radial wind, two solutions exist for circularly polarised electromagnetic modes. At large distances one of them turns into a freely expanding flow containing a vacuum wave, whereas the other decelerates, corresponding to a confined flow.

  3. X-wave mediated instability of plane waves in Kerr media

    CERN Document Server

    Conti, C

    2003-01-01

    Plane waves in Kerr media spontaneously generate paraxial X-waves (i.e. non-dispersive and non-diffractive pulsed beams) that get amplified along propagation. This effect can be considered a form of conical emission (i.e. spatio-temporal modulational instability), and can be used as a key for the interpretation of the out of axis energy emission in the splitting process of focused pulses in normally dispersive materials. A new class of spatio-temporal localized wave patterns is identified. X-waves instability, and nonlinear X-waves, are also expected in periodical Bose condensed gases.

  4. Convective Generation of Gravity Waves in Venus's Atmosphere: Gravity Wave Spectrum and Momentum Transport

    OpenAIRE

    Leroy, Stephen S.; Ingersoll, Andrew P.

    1995-01-01

    The emission of internal gravity waves from a layer of dry convection embedded within a stable atmosphere with static stability and zonal winds varying in height is calculated. This theory is applied to Venus to investigate whether these waves can help support the westward maximum of angular momentum of Venus's middle atmosphere. The emission mechanism is similar to that suggested for driving the gravity modes of the Sun and relates the amplitude and spectrum of the waves to the amplitude and...

  5. Effects of non-Maxwellian species on ion cyclotron waves propagation and absorption in magnetically confined plasmas

    International Nuclear Information System (INIS)

    Magnetically confined plasmas can contain significant concentrations of nonthermal particles, arising from neutral beam injection, fusion reactions, shock heating, or wave-driven acceleration of resonant plasma species. The associated distribution functions can depart significantly from Maxwellians, which may impact the propagation and absorption of radio frequency waves. The potential effect of these particles has been investigated using a full-wave code that has been extended to handle gyrotropic, but otherwise arbitrary distribution functions. This code has been used to numerically simulate ion cyclotron resonance heating (ICRH) in magnetic fusion plasmas in which coresonant neutral beam injection (NBI) heating may also be applied. The presence of nonthermal ion populations generated by the NBI can alter the ICRH characteristics. Two situations involving ion cyclotron range of frequency waves are presented: fast wave to ion Bernstein wave mode conversion and high harmonic fast wave electron heating. In both cases, the adequacy of an equivalent Maxwellian-based description is discussed. Results indicate that the absorption profiles are more strongly affected than the wave fields by the presence of nonthermal species

  6. Wave turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Nazarenko, Sergey [Warwick Univ., Coventry (United Kingdom). Mathematics Inst.

    2011-07-01

    Wave Turbulence refers to the statistical theory of weakly nonlinear dispersive waves. There is a wide and growing spectrum of physical applications, ranging from sea waves, to plasma waves, to superfluid turbulence, to nonlinear optics and Bose-Einstein condensates. Beyond the fundamentals the book thus also covers new developments such as the interaction of random waves with coherent structures (vortices, solitons, wave breaks), inverse cascades leading to condensation and the transitions between weak and strong turbulence, turbulence intermittency as well as finite system size effects, such as ''frozen'' turbulence, discrete wave resonances and avalanche-type energy cascades. This book is an outgrow of several lectures courses held by the author and, as a result, written and structured rather as a graduate text than a monograph, with many exercises and solutions offered along the way. The present compact description primarily addresses students and non-specialist researchers wishing to enter and work in this field. (orig.)

  7. Using Visible Spectral Information to Predict Long-Wave Infrared Spectral Emissivity: A Case Study over the Sokolov Area of the Czech Republic with an Airborne Hyperspectral Scanner Sensor

    Directory of Open Access Journals (Sweden)

    Gila Notesco

    2013-11-01

    Full Text Available Remote-sensing platforms are often comprised of a cluster of different spectral range detectors or sensors to benefit from the spectral identification capabilities of each range. Missing data from these platforms, caused by problematic weather conditions, such as clouds, sensor failure, low temporal coverage or a narrow field of view (FOV, is one of the problems preventing proper monitoring of the Earth. One of the possible solutions is predicting a detector or sensor’s missing data using another detector/sensor. In this paper, we propose a new method of predicting spectral emissivity in the long-wave infrared (LWIR spectral region using the visible (VIS spectral region. The proposed method is suitable for two main scenarios of missing data: sensor malfunctions and narrow FOV. We demonstrate the usefulness and limitations of this prediction scheme using the airborne hyperspectral scanner (AHS sensor, which consists of both VIS and LWIR spectral regions, in a case study over the Sokolov area, Czech Republic.

  8. Backward Propagation of Otoacoustic Emissions

    Institute of Scientific and Technical Information of China (English)

    HE Wenxuan; REN Tianying

    2006-01-01

    Normal mammalian ears not only detect but also generate sounds. The ear-generated sounds, I.e., otoacoustic emissions (OAEs), can be measured in the external ear canal using a tiny sensitive microphone. In spite of wide applications of OAEs in diagnosis of hearing disorders and in studies of cochlear functions, the question of how the cochlea emits sounds remains unclear. The current dominating theory is that the OAE reaches the cochlear base through a backward traveling wave. However, recently published works, including experimental data on the spatial pattern ofbasilar membrane vibrations at the emission frequency, demonstrated only forward traveling waves and no signs of backward traveling waves. These new findings indicate that the cochlea emits sounds through cochlear fluids as compression waves rather than through the basilar membrane as backward traveling waves. This article reviews different mechanisms of the backward propagation of OAEs and summarizes recent experimental results.

  9. Gravitational Waves from Gravitational Collapse

    OpenAIRE

    New Kimberly C.B.

    2002-01-01

    Gravitational wave emission from the gravitational collapse of massive stars has been studied for more than three decades. Current state of the art numerical investigations of collapse include those that use progenitors with realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non--axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational colla...

  10. Satellite observations of the QBO wave driving by Kelvin waves and gravity waves

    Science.gov (United States)

    Ern, Manfred; Preusse, Peter; Kalisch, Silvio; Riese, Martin

    2014-05-01

    The quasi-biennial oscillation (QBO) of the zonal wind in the tropical stratosphere is an important process in atmospheric dynamics influencing a wide range of altitudes and latitudes. Effects of the QBO are found also in the mesosphere and in the extra-tropics. The QBO even has influence on the surface weather and climate, for example during winter in the northern hemisphere at midlatitudes. Still, climate models have large difficulties in reproducing a realistic QBO. One reason for this deficiency are uncertainties in the wave driving by planetary waves and, in particular, gravity waves that are usually too small-scale to be resolved in global models. Different global equatorial wave modes (e.g., Kelvin waves) have been identified by longitude-time 2D spectral analysis in Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite temperature data, as well as ECMWF temperatures. We find good agreement between SABER satellite observations and ECMWF wave variances in both QBO-related temporal variations and their magnitude. Slow phase speed waves are strongly modulated by the QBO, higher phase speed waves are almost unaffected by the QBO, and ultra-fast equatorial waves can even reach the MLT region. Momentum fluxes and zonal wind drag due to Kelvin waves are derived, and the relative contribution of Kelvin waves to the QBO wind reversal from westward to eastward wind is estimated to be about 30% of the total wave driving. This is in good agreement with the general assumption that gravity waves (GWs) are probably more important for the QBO driving than global-scale waves. This is further supported by SABER and High Resolution Dynamics Limb Sounder (HIRDLS) satellite observations of gravity wave drag in the equatorial region. These observations are compared with the drag still missing in the ECMWF ERA Interim (ERAI) tropical momentum budget after considering zonal wind tendency, Coriolis force, advection terms and drag of resolved global

  11. Bayesian semiparametric power spectral density estimation in gravitational wave data analysis

    CERN Document Server

    Edwards, Matthew C; Christensen, Nelson

    2015-01-01

    The standard noise model in gravitational wave (GW) data analysis assumes detector noise is stationary and Gaussian distributed, with a known power spectral density (PSD) that is usually estimated using clean off-source data. Real GW data often depart from these assumptions, and misspecified parametric models of the PSD could result in misleading inferences. We propose a Bayesian semiparametric approach to improve this. We use a nonparametric Bernstein polynomial prior on the PSD, with weights attained via a Dirichlet process distribution, and update this using the Whittle likelihood. Posterior samples are obtained using a Metropolis-within-Gibbs sampler. We simultaneously estimate the reconstruction parameters of a rotating core collapse supernova GW burst that has been embedded in simulated Advanced LIGO noise. We also discuss an approach to deal with non-stationary data by breaking longer data streams into smaller and locally stationary components.

  12. Bayesian semiparametric power spectral density estimation with applications in gravitational wave data analysis

    Science.gov (United States)

    Edwards, Matthew C.; Meyer, Renate; Christensen, Nelson

    2015-09-01

    The standard noise model in gravitational wave (GW) data analysis assumes detector noise is stationary and Gaussian distributed, with a known power spectral density (PSD) that is usually estimated using clean off-source data. Real GW data often depart from these assumptions, and misspecified parametric models of the PSD could result in misleading inferences. We propose a Bayesian semiparametric approach to improve this. We use a nonparametric Bernstein polynomial prior on the PSD, with weights attained via a Dirichlet process distribution, and update this using the Whittle likelihood. Posterior samples are obtained using a blocked Metropolis-within-Gibbs sampler. We simultaneously estimate the reconstruction parameters of a rotating core collapse supernova GW burst that has been embedded in simulated Advanced LIGO noise. We also discuss an approach to deal with nonstationary data by breaking longer data streams into smaller and locally stationary components.

  13. Bubble Dynamics and Shock Waves

    CERN Document Server

    2013-01-01

    This volume of the Shock Wave Science and Technology Reference Library is concerned with the interplay between bubble dynamics and shock waves. It is divided into four parts containing twelve chapters written by eminent scientists. Topics discussed include shock wave emission by laser generated bubbles (W Lauterborn, A Vogel), pulsating bubbles near boundaries (DM Leppinen, QX Wang, JR Blake), interaction of shock waves with bubble clouds (CD Ohl, SW Ohl), shock propagation in polydispersed bubbly liquids by model equations (K Ando, T Colonius, CE Brennen. T Yano, T Kanagawa,  M Watanabe, S Fujikawa) and by DNS (G Tryggvason, S Dabiri), shocks in cavitating flows (NA Adams, SJ Schmidt, CF Delale, GH Schnerr, S Pasinlioglu) together with applications involving encapsulated bubble dynamics in imaging (AA Doinikov, A Novell, JM Escoffre, A Bouakaz),  shock wave lithotripsy (P Zhong), sterilization of ships’ ballast water (A Abe, H Mimura) and bubbly flow model of volcano eruptions ((VK Kedrinskii, K Takayama...

  14. Emission Trading

    OpenAIRE

    Kmoch, Daniel

    2009-01-01

    The work concerns Emission Trading Scheme from perspektive of taxes and accounting. I should show problems with emission trading. The work concerns practical example of trading with emission allowance.

  15. Third Wave.

    Science.gov (United States)

    Reed, Chris

    2000-01-01

    Third Wave is a Christian charity based in Derby (England) that offers training in vocational skills, preindustrial crafts, horticultural and agricultural skills, environmental education, and woodland survival skills to disadvantaged people at city and farm locations. Third Wave employs a holistic approach to personal development in a community…

  16. Gravitational Waves

    OpenAIRE

    Schutz, Bernard F.

    1990-01-01

    In 1989 four groups around the world proposed the construction of large-scale laser interferometric gravitational wave detectors. The author reviews the design of these detectors, the problems of analysing their data, and the theory of the sources of the gravitational waves that they are designed to detect.

  17. Wave Dragon

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter; Friis-Madsen, Erik;

    2008-01-01

    Since March 2003 a prototype of Wave Dragon has been tested in an inland sea in Denmark. This has been a great success with all subsystems tested and improved through working in an offshore environment. The project has proved the Wave Dragon device and has enabled the next stage, a production sized...

  18. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star.......Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star....

  19. Microfluidic waves.

    Science.gov (United States)

    Utz, Marcel; Begley, Matthew R; Haj-Hariri, Hossein

    2011-11-21

    The propagation of pressure waves in fluidic channels with elastic covers is discussed in view of applications to flow control in microfluidic devices. A theory is presented which describes pressure waves in the fluid that are coupled to bending waves in the elastic cover. At low frequencies, the lateral bending of the cover dominates over longitudinal bending, leading to propagating, non-dispersive longitudinal pressure waves in the channel. The theory addresses effects due to both the finite viscosity and compressibility of the fluid. The coupled waves propagate without dispersion, as long as the wave length is larger than the channel width. It is shown that in channels of typical microfluidic dimensions, wave velocities in the range of a few 10 m s(-1) result if the channels are covered by films of a compliant material such as PDMS. The application of this principle to design microfluidic band pass filters based on standing waves is discussed. Characteristic frequencies in the range of a few kHz are readily achieved with quality factors above 30. PMID:21966667

  20. Generation of spectrally-stable continuous-wave emission and ns pulses at 800 nm and 975 nm with a peak power of 4 W using a distributed Bragg reflector laser and a ridge-waveguide power amplifier

    Science.gov (United States)

    Klehr, A.; Wenzel, H.; Fricke, J.; Bugge, F.; Liero, A.; Hoffmann, Th.; Erbert, G.; Tränkle, G.

    2015-03-01

    Semiconductor based sources which emit high-power spectrally stable nearly diffraction-limited optical pulses in the nanosecond range are ideally suited for a lot of applications, such as free-space communications, metrology, material processing, seed lasers for fiber or solid state lasers, spectroscopy, LIDAR and frequency doubling. Detailed experimental investigations of 975 nm and 800 nm diode lasers based on master oscillator power amplifier (MOPA) light sources are presented. The MOPA systems consist of distributed Bragg reflector lasers (DBR) as master oscillators driven by a constant current and ridge waveguide power amplifiers which can be driven DC and by current pulses. In pulse regime the amplifiers modulated with rectangular current pulses of about 5 ns width and a repetition frequency of 200 kHz act as optical gates, converting the continuous wave (CW) input beam emitted by the DBR lasers into a train of short optical pulses which are amplified. With these experimental MOPA arrangements no relaxation oscillations in the pulse power occur. With a seed power of about 5 mW at a wavelength of 973 nm output powers behind the amplifier of about 1 W under DC injection and 4 W under pulsed operation, corresponding to amplification factors of 200 (amplifier gain 23 dB) and 800 (gain 29 dB) respectively, are reached. At 800 nm a CW power of 1 W is obtained for a seed power of 40 mW. The optical spectra of the emission of the amplifiers exhibit a single peak at a constant wavelength with a line width 50 dB. The output beams are nearly diffraction limited with beam propagation ratios M2lat ~ 1.1 and M2ver ~ 1.2 up to 4 W pulse power.

  1. A laboratory study of breaking waves

    Directory of Open Access Journals (Sweden)

    Jaros³aw Têgowski

    2004-09-01

    Full Text Available This paper deals with some aspects of the wave-breaking phenomenon. The objectives were to study wave-breaking criteria, and the probability of whitecap coverage under fully controlled wave conditions. An additional task was to in vestigate the characteristic spectral features of the noise produced by breaking waves and the acoustic energy generated during wave breaking events. A controlled experiment was carried out in the Ocean Basin Laboratory at MARINTEK, Trondheim (Norway. Waves were generated by a computer-controlled multi-flap wave maker, which reproduced a realistic pattern of the sea surface for the prescribed spectra. Using wave staff recordings and photographic techniques, correlations between the breaking parameters and the radiated acoustic emissions were established.

  2. Electromagnetic nonlinear X-waves

    CERN Document Server

    Conti, C; Trapani, P D; Valiulis, G; Jedrkiewicz, O; Trull, J

    2002-01-01

    Nonlinear optical media that are normally dispersive, support a new type of localized (nondiffractive and nondispersive) wavepackets that are X-shaped in space and time and have slower than exponential decay. High-intensity X-waves, unlike linear ones, can be formed spontaneously through a trigger mechanism of conical emission, thus playing an important role in experiments.

  3. Ship waves and lee waves

    Science.gov (United States)

    Sharman, R. D.; Wurtele, M. G.

    1983-01-01

    Dynamics analogous to those of surface ship waves on water of finite depth are noted for the three-dimensional trapped lee wave modes produced by an isolated obstacle in a stratified fluid. This vertical trapping of wave energy is modeled by uniform upstream flow and stratification, bounded above by a rigid lid, and by a semiinfinite fluid of uniform stability whose wind velocity increases exponentially with height, representing the atmosphere. While formal asymptotic solutions are produced, limited quantitative usefulness is obtained through them because of the limitations of the approximations and the infinity of modes in the solution. Time-dependent numerical models are accordingly developed for both surface ship waves and internal and atmospheric ship waves, yielding a variety of results.

  4. Acoustic emission source modeling

    Czech Academy of Sciences Publication Activity Database

    Hora, Petr; Červená, Olga

    Plzeň : University of West Bohemia, 2009 - (Adámek, V.; Zajíček, M.). s. 1-2 ISBN 978-80-7043-824-4. [Výpočtová mechanika 2009. 09.11.2009-11.11.2009, Nečtiny] R&D Projects: GA ČR GA101/09/1630 Institutional research plan: CEZ:AV0Z20760514 Keywords : acoustic emission source * wave propagation * FEM Subject RIV: BI - Acoustics

  5. Lower hybrid current drive in the presence of ICRF waves

    International Nuclear Information System (INIS)

    Motivated by recent JET results showing an enhancement in the lower hybrid current drive (LHCD) efficiency in ICRF heated plasmas, the authors have been studying the interaction of lower hybrid generated electron tails with fast Alfven waves (FAW) and ion-Bernstein waves (IBW). The IBW's are generated by mode conversion, at the hybrid resonance layers inside the plasma, of the externally launched FAW's. The numerical solutions of the Fokker-Planck equation using CQL3D show that, for the powers used in JET, the FAW cannot significantly modify the LH electron tail and, consequently, does not play a role in the enhancement of the LHCD efficiency. Similar analysis for IBW's shows that these waves play an important role in the enhancement of the current drive efficiency. Calculations show that for small kparallel's about 20% of the FAW power is mode converted to the IBW's. Previous analysis of the propagation of IBW's has shown that the electric field amplitudes are considerably enhanced as IBW propagate in toroidal plasmas. This compensates for the possibly small fraction of the total input power that mode converts to IBW's. Furthermore, IBW's interact with electrons off-axis through Landau damping on flux surfaces where LHW's generate currents. FAW's only interact with electrons near the ion cyclotron or ion-ion hybrid resonance layers which, in the case of JET, may be near the axis of the plasma while the LH waves damp well off-axis. So IBW's are more likely to enhance the LHCD efficiency. In fact, the conditions for which JET shows an enhancement in LHCD efficiency are those for which mode conversion to IBW's occurs. The authors present detailed analytical and numerical results in support of the statements made above

  6. Janus Waves

    CERN Document Server

    Papazoglou, Dimitris G; Tzortzakis, Stelios

    2016-01-01

    We show the existence of a family of waves that share a common interesting property affecting the way they propagate and focus. These waves are a superposition of twin waves, which are conjugate to each other under inversion of the propagation direction. In analogy to holography, these twin "real" and "virtual" waves are related respectively to the converging and the diverging part of the beam and can be clearly visualized in real space at two distinct foci under the action of a focusing lens. Analytic formulas for the intensity distribution after focusing are derived, while numerical and experimental demonstrations are given for some of the most interesting members of this family, the accelerating Airy and ring-Airy beams.

  7. Alfven wave

    International Nuclear Information System (INIS)

    Seven chapters are included. Chapters 1 and 2 introduce the Alfven wave and describe its linear properties in a homogeneous medium. Chapters 3 and 4 cover the effects of inhomogeneities on these linear properties. Particular emphasis is placed on the appearance of a continuum spectrum and the associated absorption of the Alfven wave which arise due to the inhomogeneity. The explanation of the physical origin of absorption is given using kinetic theory. Chapter 5 is devoted to the associated plasma instabilities. Nonlinear effects discussed in Chapter 6 include quasilinear diffusion, decay, a solitary wave, and a modulational instability. The principles of Alfven wave heating, a design example and present-day experimental results are described in Chapter 7

  8. When Shock Waves Collide

    CERN Document Server

    Hartigan, P; Frank, A; Hansen, E; Yirak, K; Liao, A S; Graham, P; Wilde, B; Blue, B; Martinez, D; Rosen, P; Farley, D; Paguio, R

    2016-01-01

    Supersonic outflows from objects as varied as stellar jets, massive stars and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures and therefore a higher-excitation spectrum than an oblique one does. In this paper we summarize the results of a series of numerical simulations and laboratory experiments designed to quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and ...

  9. Wave Measurements

    OpenAIRE

    Bazzi, Tomaso; Di Memmo, Alberico; Palini, Massimo; Sellini, Massimiliano; Fabbri, Luigi

    2011-01-01

    Purpose of the present report is the summary of the experimental campaign performed at INSEAN facilities. This campaign has been oriented to analyze the classical wave measurement systems and, furthermore, to validate the results of the numerical models. A devoted paragraph describes the main features of a new innovative and non intrusive methodology for the wave measurements aimed to perform both model and ship scale trials.

  10. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star....

  11. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Andersen, Thomas Lykke

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star....

  12. Blast Waves

    CERN Document Server

    Needham, Charles E

    2010-01-01

    The primary purpose of this text is to document many of the lessons that have been learned during the author’s more than forty years in the field of blast and shock. The writing therefore takes on an historical perspective, in some sense, because it follows the author’s experience. The book deals with blast waves propagating in fluids or materials that can be treated as fluids. It begins by distinguishing between blast waves and the more general category of shock waves. It then examines several ways of generating blast waves, considering the propagation of blast waves in one, two and three dimensions as well as through the real atmosphere. One section treats the propagation of shocks in layered gases in a more detailed manner. The book also details the interaction of shock waves with structures in particular reflections, progressing from simple to complex geometries, including planar structures, two-dimensional structures such as ramps or wedges, reflections from heights of burst, and three-dimensional st...

  13. Experimental characterization of nonlinear processes of whistler branch waves

    Science.gov (United States)

    Tejero, E. M.; Crabtree, C.; Blackwell, D. D.; Amatucci, W. E.; Ganguli, G.; Rudakov, L.

    2016-05-01

    Experiments in the Space Physics Simulation Chamber at the Naval Research Laboratory isolated and characterized important nonlinear wave-wave and wave-particle interactions that can occur in the Earth's Van Allen radiation belts by launching predominantly electrostatic waves in the intermediate frequency range with wave normal angle greater than 85 ° and measuring the nonlinearly generated electromagnetic scattered waves. The scattered waves have a perpendicular wavelength that is nearly an order of magnitude larger than that of the pump wave. Calculations of scattering efficiency from experimental measurements demonstrate that the scattering efficiency is inversely proportional to the damping rate and trends towards unity as the damping rate approaches zero. Signatures of both wave-wave and wave-particle scatterings are also observed in the triggered emission process in which a launched wave resonant with a counter-propagating electron beam generates a large amplitude chirped whistler wave. The possibility of nonlinear scattering or three wave decay as a saturation mechanism for the triggered emission is suggested. The laboratory experiment has inspired the search for scattering signatures in the in situ data of chorus emission in the radiation belts.

  14. Strong acoustic wave action

    Science.gov (United States)

    Gokhberg, M. B.

    1983-07-01

    Experiments devoted to acoustic action on the atmosphere-magnetosphere-ionosphere system using ground based strong explosions are reviewed. The propagation of acoustic waves was observed by ground observations over 2000 km in horizontal direction and to an altitude of 200 km. Magnetic variations up to 100 nT were detected by ARIEL-3 satellite near the epicenter of the explosion connected with the formation of strong field aligned currents in the magnetosphere. The enhancement of VLF emission at 800 km altitude is observed.

  15. Nonlinear wave-wave interactions and wedge waves

    Institute of Scientific and Technical Information of China (English)

    Ray Q.Lin; Will Perrie

    2005-01-01

    A tetrad mechanism for exciting long waves,for example edge waves,is described based on nonlinear resonant wave-wave interactions.In this mechanism,resonant interactions pass energy to an edge wave,from the three participating gravity waves.The estimated action flux into the edge wave can be orders of magnitude greater than the transfer fluxes derived from other competing mechanisms,such as triad interactions.Moreover,the numerical results show that the actual transfer rates into the edge wave from the three participating gravity waves are two-to three- orders of magnitude greater than bottom friction.

  16. Simulations to Usher in the Era of Gravitational Wave Astronomy

    Science.gov (United States)

    Lehner, Luis; Liebling, Steven L.

    2013-03-01

    A new era of astronomy is near, in which interferometers on Earth and pulsar timing observations will provide an entirely new view of the universe using gravitational waves. These waves will complement the very different images from electromagnetic waves (such as conventional telescopes) and will illuminate systems from which we detect no electromagnetic emission.

  17. Wave Generation Theory

    DEFF Research Database (Denmark)

    Frigaard, Peter; Høgedal, Michael; Christensen, Morten

    The intention of this manual is to provide some formulas and techniques which can be used for generating waves in hydraulic laboratories. Both long crested waves (2-D waves) and short crested waves (3-D waves) are considered.......The intention of this manual is to provide some formulas and techniques which can be used for generating waves in hydraulic laboratories. Both long crested waves (2-D waves) and short crested waves (3-D waves) are considered....

  18. Unusual radio and plasma wave phenomena observed in March 1991

    Science.gov (United States)

    Reiner, M. J.; Stone, R. G.; Fainberg, J.

    1992-01-01

    During the intense solar flare activity in March 1991 a number of unusual radio emission and Langmuir wave phenomena were observed by the radio and plasma wave (URAP) experiment on the Ulysses spacecraft. These phenomena were associated with unusual conditions in the interplanetary medium (IPM) presumably resulting from intense solar activity. Some of these URAP observations cannot be explained by mechanisms usually attributed to interplanetary (IP) radio emissions and Langmuir wave activity and require other interpretations.

  19. Newly Identified Rydberg Emission Lines in Novae

    Science.gov (United States)

    Lynch, David K.; Rudy, R. J.; Bernstein, L. S.

    2008-09-01

    Newly Identified Rydberg Emission Lines in Novae David K. Lynch, Richard. J. Rudy (The Aerospace Corporation) & Lawrence S. Bernstein (Spectral Sciences, Inc.) Novae spectra in the near infrared frequently show a set of six emission lines that have not been positively identified (Williams, Longmore, & Geballe 1996, MNRAS, 279, 804; Lynch et al. 2001, AJ, 122, 2013; Rudy et al. 2002 ApJ, 573, 794; Lynch et al. 2004 Astron. J. 127, 1089-1097). These lines are at 0.8926, 1.1114, 1.1901, 1.5545, 2.0996 and 2.425 µm ± 0.005 µm. Krautter et al. (1984 A&A 137, 304) suggested that three of the lines were due to rydberg (hydrogenic) transitions in an unspecified atomic species that was in the 4th or 5th ionization stage (core charge = 4 & 5). We believe that Krautter et al.'s explanation is correct based on 4 additional lines that we have identified in the visible and near infrared spectrum of V723 Cassiopeiae. The observed Rydberg lines appear to originate from high angular momentum states with negligible quantum defects. The species cannot be determined with any certainty because in rydberg states, the outer electron sees a nucleus shielded by the inner electrons and together the inner atom appears to have a charge of +1, like hydrogen. As a result, the atom looks hydrogenic and species such as CV, NV, OV, MgV, SiV, etc. have their rydberg transitions at very similar wavelengths. All the lines represent permitted transitions, most likely formed by recombination. Atoms with core charges 4, 5 & 6 are rarely seen in the astrophysical environment because an extremely hot radiation field is necessary to ionize them. Thermonuclear runaways on the surface of a white dwarf can reach millions of degrees K, and thus there are enough X-ray photons available to achieve the necessary high ionization levels.

  20. Gravitational waves

    CERN Document Server

    Thorne, K S

    1995-01-01

    This article reviews current efforts and plans for gravitational-wave detection, the gravitational-wave sources that might be detected, and the information that the detectors might extract from the observed waves. Special attention is paid to (i) the LIGO/VIRGO network of earth-based, kilometer-scale laser interferometers, which is now under construction and will operate in the high-frequency band (1 to 10^4 Hz), and (ii) a proposed 5-million-kilometer-long Laser Interferometer Space Antenna (LISA), which would fly in heliocentric orbit and operate in the low-frequency band (10^{-4} to 1 Hz). LISA would extend the LIGO/VIRGO studies of stellar-mass (M\\sim2 to 300 M_\\odot) black holes into the domain of the massive black holes (M\\sim1000 to 10^8M_\\odot) that inhabit galactic nuclei and quasars.

  1. Surface waves

    International Nuclear Information System (INIS)

    Two dimensional surface waves including surface tension are considered in this paper. The disturbance potential φ created by a moving concentrated pressure has been determined uniquely following Peters. Linearized free surface conditions have been utilized. The free surface elevations η(x) have been obtained and discussed for stream velocities U ≥ = min, the minimum wave velocity. The results obtained are satisfactory. It is hoped that a similar approach may help to solve the three dimensional problem. It is, of course, apprehended that it may lead to complications which may not be easy to handle theoretically. (author). 11 refs, 5 figs

  2. Emissions Trading

    NARCIS (Netherlands)

    Woerdman, Edwin; Backhaus, Juergen

    2014-01-01

    Emissions trading is a market-based instrument to achieve environmental targets in a cost-effective way by allowing legal entities to buy and sell emission rights. The current international dissemination and intended linking of emissions trading schemes underlines the growing relevance of this instr

  3. Power absorption during nonlinear electron cyclotron wave-particle interaction

    International Nuclear Information System (INIS)

    The linear theory of wave absorption and the quasilinear theory of the evolution of the distribution function are presently the main tools for a quantitative description of ECRH and ECCD in fusion devices. However the applicability of this theories is violated for some ECRH (ECCD) scenarios in typical experimental conditions. In particular this is true for one of the basic scenarios where the 2. harmonic electron cyclotron resonance for the extraordinary mode (X-mode) is used. In this paper a numerical model for ECRH and ECCD which consistently takes into account nonlinear wave-particle interaction has been developed. The results of computations show that the distortion of the particle distribution function from Maxwellian is strong for parameters typical for present day ECRH experiments. These leads to a reduction of the absorption, consequent broadening of the absorption profile and incomplete absorption. The distortion of the particle distribution function is essentially different from what is expected from the quasilinear theory where a Fokker-Planck equation is assumed to be valid. The positive derivative of the distribution function indicates that nonlinear effects of ECRH may cause the electron Bernstein wave instability. The modelling of ECCD at the 2. harmonic X-mode resonance shows that the effect of power redistribution in velocity space can especially be important for current drive. Therefore, for ECCD the absorption should be taken into account correctly by using nonlinear computations. With increasing both magnetic field and size of the beam, the nonlinear effects become more important. Therefore, the proper account of nonlinear effects is ultimate for reactor-scale devices

  4. Nature of microstructure in pulsar radio emission

    OpenAIRE

    Machabeli, George; Khechinashvili, David; Melikidze, George; Shapakidze, David

    2000-01-01

    We present a model for microstructure in pulsar radio emission. We propose that micropulses result from the alteration of the radio wave generation region by nearly transverse drift waves propagating across the pulsar magnetic field and encircling the bundle of the open magnetic field lines. It is demonstrated that such waves can modify significantly curvature of these dipolar field lines. This in turn affects strongly fulfillment of the resonance conditions necessary for the excitation of ra...

  5. Characteristics of Spherical Shock Wave and Circular Pulse Jet Generated by Discharge of Propagating Shock Wave at Open End of Tube

    Institute of Scientific and Technical Information of China (English)

    Tsukasa Irie; Tsuyoshi Yasunobu; Hideo Kashimura; Toshiaki Setoguchi; Kazuyasu Matsuo

    2003-01-01

    When the shock wave propagating in the straight circular tube reaches at the open end, the impulsive wave is generated by the emission of a shock wave from an open end, and unsteady pulse jet is formed near the open end behind the impulsive wave under the specific condition. The pulse jet transits to spherical shock wave with the increase in the strength of shock wave. The strength is dependent on the Mach number of shock wave, which attenuates by propagation distance from the open end. In this study, the mechanism of generating the unsteady pulse jet, the characteristics of the pressure distribution in the flow field and the emission of shock wave from straight circular tube which has the infinite flange at open end are analyzed numerically by the TVD method. Strength of spherical shock wave, relation of shock wave Mach number, distance decay of spherical shock wave and directional characteristics are clarified.

  6. Shallow Water Waves and Solitary Waves

    CERN Document Server

    Hereman, Willy

    2013-01-01

    Encyclopedic article covering shallow water wave models used in oceanography and atmospheric science. Sections: Definition of the Subject; Introduction and Historical Perspective; Completely Integrable Shallow Water Wave Equations; Shallow Water Wave Equations of Geophysical Fluid Dynamics; Computation of Solitary Wave Solutions; Numerical Methods; Water Wave Experiments and Observations; Future Directions, and Bibliography.

  7. Emission Facilities - Air Emission Plants

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — Represents the Primary Facility type Air Emission Plant (AEP) point features. Air Emissions Plant is a DEP primary facility type related to the Air Quality Program....

  8. Wave Dragon

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    På foranledning af Löwenmark F.R.I, er der udført numeriske beregninger af Wave Dragons (herefter WD) armes effektivitet for forskellige geometriske udformninger. 5 geometriske modeller, hvor WD's arme er forkortet/forlænget er undersøgt for 3 forskellige drejninger af armene. I alt er 15...

  9. Gravitational Waves from The Newtonian plus H\\'enon-Heiles System

    OpenAIRE

    Kokubun, F.

    1998-01-01

    In this work we analyze the emission of gravitational waves from a gravitational system described by a Newtonian term plus a H\\'enon-Heiles term. The main concern is to analyze how the inclusion of the Newtonian term changes the emission of gravitational waves, considering its emission in the chaotic and regular regime.

  10. Emission inventory; Inventaire des emissions

    Energy Technology Data Exchange (ETDEWEB)

    Fontelle, J.P. [CITEPA, Centre Interprofessionnel Technique d`Etudes de la Pollution Atmospherique, 75 - Paris (France)

    1997-12-31

    Statistics on air pollutant (sulfur dioxide, nitrogen oxides and ammonium) emissions, acid equivalent emissions and their evolution since 1990 in the various countries of Europe and the USA, are presented. Emission data from the industrial, agricultural, transportation and power sectors are given, and comparisons are carried out between countries based on Gnp and population, pollution import/export fluxes and compliance to the previous emission reduction objectives

  11. Excitation and conversion of electromagnetic waves in pulsar magnetospheres

    OpenAIRE

    Gogoberidze, G.; Machabeli, G. Z.; V. V. Usov

    2007-01-01

    We demonstrate that nonlinear decay of obliquely propagating Langmuir waves into Langmuir and Alfven waves (L --> L'+A) is possible in a one-dimensional, highly relativistic, streaming, pair plasma. Such a plasma may be in the magnetospheres of pulsars. It is shown that the characteristic frequency of generated Alfven waves is much less than the frequency of Langmuir waves and may be consistent with the observational data on the radio emission of pulsars.

  12. High frequency fast wave results from the CDX-U spherical torus

    International Nuclear Information System (INIS)

    The Current Drive Experiment-Upgrade (CDX-U) is the first spherical torus (ST) to investigate radio frequency (RF) heating and current drive. To address the concern that large magnetic field line pitch at the outboard midplane of ST's could inhibit successful coupling to the high harmonic fast wave (HHFW), a rotatable, two strap antenna was installed on CDX-U. Parasitic loading and impurity generation were discovered to be weak and nearly independent of antenna phasing and angle over a wide range, and fast wave electron heating has been observed. Plasma densities up to about 1012cm-3 were obtained with noninductive startup solely with HHFW. New ST diagnostics under development on CDX-U include a multilayer mirror (MLM) detector to measure ultrasoft X-rays, a twelve spatial point Thomson scattering (TS) system, and an Electron Bernstein Wave (EBW) system for both electron heating and electron temperature measurements. Preliminary experiments with a boron low velocity edge micropellet injector have also been performed, and further studies of its effectiveness for impurity control will be conducted with a variety of spectroscopic and imaging diagnostics on CDX-U. (author)

  13. Computer simulations for direct conversion of the HF electromagnetic wave into the upper hybrid wave in ionospheric heating experiments

    OpenAIRE

    Ueda, H. O.; Omura, Y.; Matsumoto, H

    1998-01-01

    Excitation of upper hybrid waves associated with the ionospheric heating experiments is assumed to be essential in explaining some of the features of stimulated electromagnetic emissions (SEE). A direct conversion process is proposed as an excitation mechanism of the upper hybrid waves where the energy of an obliquely propagating electromagnetic pump wave is converted into the electrostatic upper hybrid waves due to small-scale density irregularities. We performed electromagnetic particle-in-...

  14. Fast Magnetosonic Waves Driven by Gravitational Waves

    OpenAIRE

    Papadopoulos, D.; Stergioulas, N.; Vlahos, L.; Kuijpers, J.

    2001-01-01

    The propagation of a gravitational wave (GW) through a magnetized plasma is considered. In particular, we study the excitation of fast magnetosonic waves (MSW) by a gravitational wave, using the linearized general-relativistic hydromagnetic equations. We derive the dispersion relation for the plasma, treating the gravitational wave as a perturbation in a Minkowski background space-time. We show that the presence of gravitational waves will drive magnetosonic waves in the plasma and discuss th...

  15. VLF wave injections from the ground

    Science.gov (United States)

    Helliwell, R. A.

    1983-01-01

    Experiments on wave-particle interactions using VLF whistler-mode waves injected into the magnetosphere from Antartica are described. The injected signals are single-frequency coherent waves whose amplitudes and frequencies may be changed slowly with time, or else two or more coherent wave trains transmitted simultaneously to determine the nature of the response to multifrequency excitation. The waves may be amplified 30 dB or more and may trigger intense emissions having bandwidths that vary from a few to several hundred Hertz. In most cases significant growth and triggering occur only when the driving signal is essentially monochromatic (bandwidth 10 Hz). If two frequencies are transmitted simultaneously the signal at the lower frequency tends to be suppressed by 20 dB or more. These results are interpreted in terms of a feedback interaction between the waves and counter-streaming cyclotron resonant electrons in a region several hundred wavelengths long, centered on the magnetic equator.

  16. Curvature-drift instability fails to generate pulsar radio emission

    OpenAIRE

    Kaganovich, Alexander; Lyubarsky, Yuri

    2010-01-01

    The curvature drift instability has long been considered as a viable mechanism for pulsar radio emission. We reconsidered this mechanism by finding an explicit solution describing propagation of short-wave electro-magnetic waves in a plasma flow along curved magnetic field lines. We show that even though the waves could be amplified, the amplification factor remains very close to unity therefore this mechanism is unable to generate high brightness temperature emission from initial weak fluctu...

  17. Collimated directional emission from a peanut-shaped microresonator

    OpenAIRE

    Shu, Fang-Jie; Zou, Chang-Ling; Sun, Fang-Wen; Xiao, Yun-Feng

    2011-01-01

    Collimated directional emission is essentially required an asymmetric resonant cavity. In this paper, we theoretically investigate a type of peanut-shaped microcavity which can support highly directional emission with the emission divergence as small as 2.5o. The mechanism of the collimated emission is explained with the short-term ray trajectory and the intuitive lens model in detail. Wave simulation also confirms these results. This extremely narrow divergence of the emission holds a great ...

  18. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter; Brorsen, Michael

    Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004.......Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004....

  19. Gravitational waves

    CERN Document Server

    Ciufolini, I; Moschella, U; Fre, P

    2001-01-01

    Gravitational waves (GWs) are a hot topic and promise to play a central role in astrophysics, cosmology, and theoretical physics. Technological developments have led us to the brink of their direct observation, which could become a reality in the coming years. The direct observation of GWs will open an entirely new field: GW astronomy. This is expected to bring a revolution in our knowledge of the universe by allowing the observation of previously unseen phenomena, such as the coalescence of compact objects (neutron stars and black holes), the fall of stars into supermassive black holes, stellar core collapses, big-bang relics, and the new and unexpected.With a wide range of contributions by leading scientists in the field, Gravitational Waves covers topics such as the basics of GWs, various advanced topics, GW detectors, astrophysics of GW sources, numerical applications, and several recent theoretical developments. The material is written at a level suitable for postgraduate students entering the field.

  20. Directional emission of stadium-shaped microlasers

    International Nuclear Information System (INIS)

    The far-field emission of two-dimensional stadium-shaped dielectric cavities is investigated. Microlasers with such shape present a highly directional emission. We provide experimental evidence of the dependence of the emission directionality on the shape of the stadium, in good agreement with ray numerical simulations. We develop an analytical geometrical optics model which permits to account for the main observed features. Wave numerical calculations confirm the results

  1. Shock Waves

    CERN Document Server

    Jiang, Z

    2005-01-01

    The International Symposium on Shock Waves (ISSW) is a well established series of conferences held every two years in a different location. A unique feature of the ISSW is the emphasis on bridging the gap between physicists and engineers working in fields as different as gas dynamics, fluid mechanics and materials sciences. The main results presented at these meetings constitute valuable proceedings that offer anyone working in this field an authoritative and comprehensive source of reference.

  2. From blast wave to observation

    OpenAIRE

    Eerten, van, H.; Wijers, R. A. M. J.

    2008-01-01

    Gamma-ray burst (GRB) afterglows are well described by synchrotron emission originating from the interaction between a relativistic blast wave and the external medium surrounding the GRB progenitor. We introduce a code to reconstruct spectra and light curves from arbitrary fluid configurations, making it especially suited to study the effects of fluid flows beyond those that can be described using analytical approximations. As a check and first application of our code we use it to fit the sca...

  3. Radiation from cosmic blast waves

    International Nuclear Information System (INIS)

    A study is made of the dynamics of blast waves, of their internal structure and of the Bremsstrahlung radiation from the shocked plasma in conditions when the cooling time is longer than the expansion time. Models appropriate for the interpretation of the X-ray sources associated with supernova remnants and with the explosive activity of the radiogalaxies in clusters of galaxies are computed and discussed; the inverse Compton emission from continuously injected relativistic electrons is included. (orig.)

  4. Gravitational Waves from Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    Chris L. Fryer

    2011-01-01

    Full Text Available Gravitational-wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion-induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

  5. Gravitational waves from gravitational collapse

    Energy Technology Data Exchange (ETDEWEB)

    Fryer, Christopher L [Los Alamos National Laboratory; New, Kimberly C [Los Alamos National Laboratory

    2008-01-01

    Gravitational wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

  6. A coronal wave as CME footprint

    CERN Document Server

    Delannée, Cécile

    2013-01-01

    I report a coronal wave observed in Fexii, soft X-ray, and Halpha on November 6, 2006, jointly with a CME and a flare to show the spatial and temporal relation of the wave and the CME. I also take advantage of the spectral resolution of the wave to obtain an approximation of its temperature. Finally, I compare the magnetic field topology to the wave location. The observations in two band passes show bright fronts that are co-spatial when observed at the same time, therefore I believe that the same wave is observed in different band passes. The wave front is not observable in Halpha, but just in Fexii and in soft X-ray, indicating that the temperature of the wave front is slightly higher than the chromospheric temperature. The ratio of emission through two SXI filters gives a temperature of 7 10^6 K for the wave front. The northern-most edge of the CME footprint related to this wave corresponds to the last location of the wave on the limb. The image processing reveals stationary brightenings produced on the pa...

  7. New mechanism of pulsar radio emission

    OpenAIRE

    Gedalin, M.; Gruman, E.; Melrose, D. B.

    2002-01-01

    It is shown that pulsar radio emission can be generated effectively through a streaming motion in the polar-cap regions of a pulsar magnetosphere causing nonresonant growth of waves that can escape directly. As in other beam models, a relatively low-energy high-density beam is required. The instability generates quasi-transverse waves in a beam mode at frequencies that can be well below the resonant frequency. As the waves propagate outward growth continues until the height at which the wave ...

  8. Impact of Wave Dragon on Wave Climate

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Tedd, James; Kramer, Morten;

    This report is an advisory paper for use in determining the wave dragon effects on hydrography, by considering the effect on the wave climate in the region of a wave dragon. This is to be used in the impact assessment for the Wave Dragon pre-commercial demonstrator....

  9. Geometrical vs wave optics under gravitational waves

    CERN Document Server

    Angélil, Raymond

    2015-01-01

    We present some new derivations of the effect of a plane gravitational wave on a light ray. A simple interpretation of the results is that a gravitational wave causes a phase modulation of electromagnetic waves. We arrive at this picture from two contrasting directions, namely null geodesics and Maxwell's equations, or, geometric and wave optics. Under geometric optics, we express the geodesic equations in Hamiltonian form and solve perturbatively for the effect of gravitational waves. We find that the well-known time-delay formula for light generalizes trivially to massive particles. We also recover, by way of a Hamilton-Jacobi equation, the phase modulation obtained under wave optics. Turning then to wave optics, rather than solving Maxwell's equations directly for the fields, as in most previous approaches, we derive a perturbed wave equation (perturbed by the gravitational wave) for the electromagnetic four-potential. From this wave equation it follows that the four-potential and the electric and magnetic...

  10. Response to “Comment on ‘Generalized dispersion relation for electron Bernstein waves in a non-Maxwellian magnetized anisotropic plasma’” [Phys. Plasmas 22, 024701 (2015)

    International Nuclear Information System (INIS)

    Sharifi and Parvazian have presented comments on our paper by questioning the validity of the results. The plots of different curves of kappa and (r, q) distributions produced by them are incorrect. They pretended as if we have made claim that our results are valid for large arguments of product of Bessel Function, whereas Neumann's series expansion is valid only for small arguments. In our paper, no claim is made that the results are valid for all values of b. Our results are valid only for b ≪ 1. The results plotted by the commenters are incorrect and in this response we are presenting correct plots of dispersion curves

  11. Wave dispersion in the hybrid-Vlasov model: Verification of Vlasiator

    International Nuclear Information System (INIS)

    Vlasiator is a new hybrid-Vlasov plasma simulation code aimed at simulating the entire magnetosphere of the Earth. The code treats ions (protons) kinetically through Vlasov's equation in the six-dimensional phase space while electrons are a massless charge-neutralizing fluid [M. Palmroth et al., J. Atmos. Sol.-Terr. Phys. 99, 41 (2013); A. Sandroos et al., Parallel Comput. 39, 306 (2013)]. For first global simulations of the magnetosphere, it is critical to verify and validate the model by established methods. Here, as part of the verification of Vlasiator, we characterize the low-β plasma wave modes described by this model and compare with the solution computed by the Waves in Homogeneous, Anisotropic Multicomponent Plasmas (WHAMP) code [K. Rönnmark, Kiruna Geophysical Institute Reports No. 179, 1982], using dispersion curves and surfaces produced with both programs. The match between the two fundamentally different approaches is excellent in the low-frequency, long wavelength range which is of interest in global magnetospheric simulations. The left-hand and right-hand polarized wave modes as well as the Bernstein modes in the Vlasiator simulations agree well with the WHAMP solutions. Vlasiator allows a direct investigation of the importance of the Hall term by including it in or excluding it from Ohm's law in simulations. This is illustrated showing examples of waves obtained using the ideal Ohm's law and Ohm's law including the Hall term. Our analysis emphasizes the role of the Hall term in Ohm's law in obtaining wave modes departing from ideal magnetohydrodynamics in the hybrid-Vlasov model

  12. Measurement of stimulated Hawking emission in an analogue system

    CERN Document Server

    Weinfurtner, Silke; Penrice, Matthew C J; Unruh, William G; Lawrence, Gregory A

    2010-01-01

    There is a mathematical analogy between the propagation of fields in a general relativistic space-time and long (shallow water) surface waves on moving water. Hawking argued that black holes emit thermal radiation via a quantum spontaneous emission. Similar arguments predict the same effect near wave horizons in fluid flow. By placing a streamlined obstacle into an open channel flow we create a region of high velocity over the obstacle that can include wave horizons. Long waves propagating upstream towards this region are blocked and converted into short (deep water) waves. This is the analogue of the stimulated emission by a white hole (the time inverse of a black hole), and our measurements of the amplitudes of the converted waves demonstrate the thermal nature of the conversion process for this system. Given the close relationship between stimulated and spontaneous emission, our findings attest to the generality of the Hawking process.

  13. Gravitational waves in geometric scalar gravity

    CERN Document Server

    Toniato, J D

    2016-01-01

    We investigate the description of gravitational waves in the geometric scalar theory of gravity (GSG). The GSG belongs to a class of theories such that gravity is described by a single scalar field and the associated physical metric describing the spacetime is constructed from a disformal transformation of Minkowski geometry. In this theory, gravitational waves have a longitudinal polarization mode, besides others modes that are observer dependent. We examine the orbital variation of a binary system due to the emission of gravitational waves, showing that GSG can also be successful in explaining this phenomena.

  14. When Shock Waves Collide

    Science.gov (United States)

    Hartigan, P.; Foster, J.; Frank, A.; Hansen, E.; Yirak, K.; Liao, A. S.; Graham, P.; Wilde, B.; Blue, B.; Martinez, D.; Rosen, P.; Farley, D.; Paguio, R.

    2016-06-01

    Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures, and therefore a higher-excitation spectrum than does an oblique shock. In this paper, we summarize the results of a series of numerical simulations and laboratory experiments designed to quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and subcritical angles, larger ones persist in these situations and can regrow if the intersection angle changes to become more favorable. The experimental and numerical results show that although Mach stems occur only over a limited range of intersection angles and size scales, within these ranges they are relatively robust, and hence are a viable explanation for variable bright knots observed in Hubble Space Telescope images at the intersections of some bow shocks in stellar jets.

  15. Climate change impact on wave energy in the Persian Gulf

    Science.gov (United States)

    Kamranzad, Bahareh; Etemad-Shahidi, Amir; Chegini, Vahid; Yeganeh-Bakhtiary, Abbas

    2015-06-01

    Excessive usage of fossil fuels and high emission of greenhouse gases have increased the earth's temperature, and consequently have changed the patterns of natural phenomena such as wind speed, wave height, etc. Renewable energy resources are ideal alternatives to reduce the negative effects of increasing greenhouse gases emission and climate change. However, these energy sources are also sensitive to changing climate. In this study, the effect of climate change on wave energy in the Persian Gulf is investigated. For this purpose, future wind data obtained from CGCM3.1 model were downscaled using a hybrid approach and modification factors were computed based on local wind data (ECMWF) and applied to control and future CGCM3.1 wind data. Downscaled wind data was used to generate the wave characteristics in the future based on A2, B1, and A1B scenarios, while ECMWF wind field was used to generate the wave characteristics in the control period. The results of these two 30-yearly wave modelings using SWAN model showed that the average wave power changes slightly in the future. Assessment of wave power spatial distribution showed that the reduction of the average wave power is more in the middle parts of the Persian Gulf. Investigation of wave power distribution in two coastal stations (Boushehr and Assalouyeh ports) indicated that the annual wave energy will decrease in both stations while the wave power distribution for different intervals of significant wave height and peak period will also change in Assalouyeh according to all scenarios.

  16. EIT waves and coronal magnetic field diagnostics

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Magnetic field in the solar lower atmosphere can be measured by the use of the Zeeman and Hanle effects. By contrast, the coronal magnetic field well above the solar surface, which directly controls various eruptive phenomena, can not be precisely measured with the traditional techniques. Several attempts are being made to probe the coronal magnetic field, such as force-free extrapolation based on the photospheric magnetograms, gyroresonance radio emissions, and coronal seismology based on MHD waves in the corona. Compared to the waves trapped in the localized coronal loops, EIT waves are the only global-scale wave phenomenon, and thus are the ideal tool for the coronal global seismology. In this paper, we review the observations and modelings of EIT waves, and illustrate how they can be applied to probe the global magnetic field in the corona.

  17. Efficient Wave Energy Amplification with Wave Reflectors

    DEFF Research Database (Denmark)

    Kramer, Morten Mejlhede; Frigaard, Peter Bak

    2002-01-01

    Wave Energy Converters (WEC's) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased to approximately 130......-140%. In the paper a procedure for calculating the efficiency and optimizing the geometry of wave reflectors are described, this by use of a 3D boundary element method. The calculations are verified by laboratory experiments and a very good agreement is found. The paper gives estimates of possible power...... benifit for different geometries of the wave reflectors and optimal geometrical design parameters are specified. On this basis inventors of WEC's can evaluate whether a specific WEC possible could benefit from wave reflectors....

  18. Ion absorption effects in high-harmonic fast wave ray tracing theory

    International Nuclear Information System (INIS)

    Effects of finite ion temperature on the propagation and absorption characteristics of high-harmonic fast waves (HHFW) are investigated theoretically using a hot electron (cold ion) ray tracing code in combination with solutions of the full hot plasma dispersion relation. Ray tracing is performed on numerical solutions of the Grad-Shafranov equation and the hot plasma dispersion relation is solved along the resultant ray trajectory using the cold ion n(parallelsign). As was observed previously (see Ref. [1]), for typical expected plasma parameters in the National Spherical Torus Experiment (NSTX) [2], ion absorption begins to appear between 0.5 and 1.0 keV local ion temperature at high deuterium cyclotron harmonics. Further, the ion power absorption rate is predicted to depend strongly on the launched parallel wavenumber [3,4]. Ray tracing on the full hot plasma dispersion relation has been attempted, but generally fails at high ion temperature near cyclotron harmonics primarily because the group velocity is ill-behaved. Such behavior usually suggests mode conversion to the ion-Bernstein wave (IBW). However, at sufficiently high n(parallelsign), mode conversion becomes negligible and the total power flux (Poynting+kinetic) is positive definite, while ray tracing still fails. The underlying cause of this apparent paradox is discussed. (c) 1999 American Institute of Physics

  19. Nonlinear MHD Waves in a Prominence Foot

    Science.gov (United States)

    Ofman, L.; Knizhnik, K.; Kucera, T.; Schmieder, B.

    2015-11-01

    We study nonlinear waves in a prominence foot using a 2.5D MHD model motivated by recent high-resolution observations with Hinode/Solar Optical Telescope in Ca ii emission of a prominence on 2012 October 10 showing highly dynamic small-scale motions in the prominence material. Observations of Hα intensities and of Doppler shifts show similar propagating fluctuations. However, the optically thick nature of the emission lines inhibits a unique quantitative interpretation in terms of density. Nevertheless, we find evidence of nonlinear wave activity in the prominence foot by examining the relative magnitude of the fluctuation intensity (δI/I ˜ δn/n). The waves are evident as significant density fluctuations that vary with height and apparently travel upward from the chromosphere into the prominence material with quasi-periodic fluctuations with a typical period in the range of 5-11 minutes and wavelengths qualitative agreement with the propagation speed of the detected waves. The 2.5D MHD numerical model is constrained with the typical parameters of the prominence waves seen in observations. Our numerical results reproduce the nonlinear fast magnetosonic waves and provide strong support for the presence of these waves in the prominence foot. We also explore gravitational MHD oscillations of the heavy prominence foot material supported by dipped magnetic field structure.

  20. Emission of the THz waves from large area mesas of superconducting Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+δ} by the injection of spin polarized current

    Energy Technology Data Exchange (ETDEWEB)

    Turkoglu, F., E-mail: fulyaturkoglu@iyte.edu.tr [Department of Physics, Izmir Institute of Technology, 35430 Urla Izmir (Turkey); Ozyuzer, L.; Koseoglu, H.; Demirhan, Y. [Department of Physics, Izmir Institute of Technology, 35430 Urla Izmir (Turkey); Preu, S.; Malzer, S. [Max Planck Optics Group, University of Erlangen-Nurnberg, Erlangen (Germany); Simsek, Y. [Physical Institute III, University of Erlangen-Nurnberg, Erlangen (Germany); Wang, H.B. [National Institute for Materials Science, Tsukuba (Japan); Muller, P. [Physical Institute III, University of Erlangen-Nurnberg, Erlangen (Germany)

    2013-08-15

    Highlights: ► THz emission was achieved from as-grown mesas due to injection of spin polarized current. ► Bump in return branch of I–V curve was observed due to radiation. ► The necessity of adjustment of doping level for THz emission was eliminated. -- Abstract: Rectangular Au/Co/Au/Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+δ} (Bi2212) mesa structures with large areas and high thicknesses were fabricated on as-grown Bi2212 single crystals in order to obtain small critical current from as-grown mesas by the injection of spin polarized current and so eliminate the adjustment of doping level for successful THz emission. We have performed c-axis resistance versus temperature (R–T), current–voltage (I–V) characteristics and bolometer measurements. It is the first time that THz emission has been observed from as-grown mesas due to injection of spin polarized current.