WorldWideScience

Sample records for plasma wave emissions

  1. Fundamental plasma emission involving ion sound waves

    Science.gov (United States)

    Cairns, Iver H.

    1987-01-01

    The theory for fundamental plasma emission by the three-wave processes L + or - S to T (where L, S and T denote Langmuir, ion sound and transverse waves, respectively) is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes are identified. In addition the rates, path-integrated wave temperatures, and limits on the brightness temperature of the radiation are derived.

  2. Electron Bernstein Wave Emission from RFP Plasmas

    Science.gov (United States)

    Nornberg, M. D.; Thomas, M.; Anderson, J.; Forest, C. B.

    1998-11-01

    Electron cyclotron emission (ECE) has proven to be a powerfull diagnostic tool in tokamak plasmas for determining the time evolution of the electron temperature profile. The standard technique of observing O-mode or X-mode electromagnetic waves normal to the magnetic field is not applicable to reversed field pinch (RFP) plasmas since the plasma frequency is much larger than the electron cyclotron frequency. We are investigating the use of electron Bernstein waves (presumed to be in thermal equilibrium with the electrons) through the aip.org/journal_cgi/ getpdf?KEY=PRLTAO&cvips=PRLTAO000078000018003467000001>O-X-B mode conversion process. At oblique incidence, the evanescent layer separating the plamsa cutoff from the cyclotron cutoff vanishes, allowing conversion of the Bernstein mode waves to the extraordinary mode and finally to the ordinary mode. The O-mode radiation is received by a phased array antenna consisting of two waveguides on the edge of the plasma, and the spectrum of emitted radiation is measured using a radiometer spanning 4-8 GHz. In addition to providing information about the electron temperature profile, the spectrum can provide a novel method of measuring the central magnetic field strength for current profile reconstructions.

  3. High latitude electromagnetic plasma wave emissions

    Science.gov (United States)

    Gurnett, D. A.

    1983-01-01

    The principal types of electromagnetic plasma wave emission produced in the high latitude auroral regions are reviewed. Three types of radiation are described: auroral kilometric radiation, auroral hiss, and Z mode radiation. Auroral kilometric radiation is a very intense radio emission generated in the free space R-X mode by electrons associated with the formation of discrete auroral arcs in the local evening. Theories suggest that this radiation is an electron cyclotron resonance instability driven by an enhanced loss cone in the auroral acceleration region at altitudes of about 1 to 2 R sub E. Auroral hiss is a somewhat weaker whistler mode emission generated by low energy (100 eV to 10 keV) auroral electrons. The auroral hiss usually has a V shaped frequency time spectrum caused by a freqency dependent beaming of the whistler mode into a conical beam directed upward or downward along the magnetic field.

  4. Second harmonic plasma emission involving ion sound waves

    Science.gov (United States)

    Cairns, Iver H.

    1987-01-01

    The theory for second harmonic plasma emission by the weak turbulence (or random phase) processes L + L + or - S to T, proceeding in two three-wave steps, L + or - S to L prime and L + L prime to T, where L, S and T denote Langmuir, ion sound and electromagnetic waves, respectively, is developed. Kinematic constraints on the characteristics and growth lengths of waves participating in the wave processes, and constraints on the characteristics of the source plasma, are derived. Limits on the brightness temperature of the radiation and the levels of the L prime and S waves are determined. Expressions for the growth rates and path-integrated wave temperatures are derived for simple models of the wave spectra and source plasma.

  5. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Coroniti, F.V.; Greenstadt, E.W.; Moses, S.L. [TRW Space and Electronics Group, Redondo Beach, CA (United States); Tsurutani, B.T.; Smith, E.J. [California Institute of Technology, Pasadena, CA (United States)

    1994-12-01

    In early September, 1983 ISEE-3 made a long traversal of the distant dawnside magnetosheath starting near x = {minus}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 (<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}. 7 refs., 5 figs.

  7. 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.

  8. 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.

  9. Stimulated Emission of Fast Alfvén Waves within Magnetically Confined Fusion Plasmas

    Science.gov (United States)

    Cook, J. W. S.; Dendy, R. O.; Chapman, S. C.

    2017-05-01

    A fast Alfvén wave with a 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 midplane 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 "α -particle channeling" scenario for the first time.

  10. Terahertz radiation emission from plasma beat-wave interactions with a relativistic electron beam

    Science.gov (United States)

    Gupta, D. N.; Kulagin, V. V.; Suk, H.

    2017-10-01

    We present a mechanism to generate terahertz radiation from laser-driven plasma beat-wave interacting with an electron beam. The theory of the energy transfer between the plasma beat-wave and terahertz radiation is elaborated through nonlinear coupling in the presence of a negative-energy relativistic electron beam. An expression of terahertz radiation field is obtained to find out the efficiency of the process. Our results show that the efficiency of terahertz radiation emission is strongly sensitive to the electron beam energy. Emitted field strength of the terahertz radiation is calculated as a function of electron beam velocity.

  11. A Fokker-Planck operator for the emission and absorption of electron plasma waves in a magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ware, A.A.

    1993-03-01

    For slab geometry the perturbation of the electrostatic wake of a superthermal test electron in a magnetized plasma ({omega}{sub ce} {much_gt} {omega}{sub pe}) due to moderate magnetic shear is determined. Allowing for the spherical symmetry of the surfaces of constant phase to the rear of the test electron, the ``resonant`` field electrons causing the damping of the wave in a magnetic surface at a distance x from the test electron are those with parallel velocity {upsilon}{prime}{parallel} = {upsilon}{parallel} cos {beta} cos({beta} + {gamma}). Here {beta} is the angle between the emitted ray and B(0), {gamma} is the angle between B(0) and B(x) and {upsilon}{parallel} is the velocity of the test electron. As a result the damping in the WKB approximation for the wave emission is a function of both the angle of emission and {gamma}. A Fokker-Planck equation is derived for the rate of change of the electron distribution function (f) due to the emission and absorption of the waves under these conditions. f is assumed approximately Maxwellian for {upsilon}{parallel} > {upsilon}{sub T}.

  12. A Fokker-Planck operator for the emission and absorption of electron plasma waves in a magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ware, A.A.

    1993-03-01

    For slab geometry the perturbation of the electrostatic wake of a superthermal test electron in a magnetized plasma ([omega][sub ce] [much gt] [omega][sub pe]) due to moderate magnetic shear is determined. Allowing for the spherical symmetry of the surfaces of constant phase to the rear of the test electron, the resonant'' field electrons causing the damping of the wave in a magnetic surface at a distance x from the test electron are those with parallel velocity [upsilon][prime][parallel] = [upsilon][parallel] cos [beta] cos([beta] + [gamma]). Here [beta] is the angle between the emitted ray and B(0), [gamma] is the angle between B(0) and B(x) and [upsilon][parallel] is the velocity of the test electron. As a result the damping in the WKB approximation for the wave emission is a function of both the angle of emission and [gamma]. A Fokker-Planck equation is derived for the rate of change of the electron distribution function (f) due to the emission and absorption of the waves under these conditions. f is assumed approximately Maxwellian for [upsilon][parallel] > [upsilon][sub T].

  13. Characterization of microwave plasma in a multicusp using 2D emission based tomography: Bessel modes and wave absorption

    Science.gov (United States)

    Rathore, Kavita; Bhattacharjee, Sudeep; Munshi, Prabhat

    2017-06-01

    A tomographic method based on the Fourier transform is used for characterizing a microwave plasma in a multicusp (MC), in order to obtain 2D distribution of plasma emissions, plasma (electron) density (Ne) and temperature (Te). The microwave plasma in the MC is characterized as a function of microwave power, gas pressure, and axial distance. The experimentally obtained 2D emission profiles show that the plasma emissions are generated in a circular ring shape. There are usually two bright rings, one at the plasma core and another near the boundary. The experimental results are validated using a numerical code that solves Maxwell's equations inside a waveguide filled with a plasma in a magnetic field, with collisions included. It is inferred that the dark and bright circular ring patterns are a result of superposition of Bessel modes (TE11 and TE21) of the wave electric field inside the plasma filled MC, which are in reasonable agreement with the plasma emission profiles. The tomographically obtained Ne and Te profiles indicate higher densities in the plasma core (˜1010 cm-3) and enhanced electron temperature in the ECR region (˜13 eV), which are in agreement with earlier results using a Langmuir probe and optical emission spectroscopy (OES) diagnostics.

  14. Vacuum ultraviolet emission from hydrogen microwave plasmas driven by surface waves

    Science.gov (United States)

    Espinho, S.; Felizardo, E.; Tatarova, E.

    2016-10-01

    The vacuum ultraviolet (VUV) radiation emitted by hydrogen surface-wave-driven plasmas operating at microwave frequency (2.45 GHz) and low-pressure conditions (0.1-2 mbar) was investigated, in particular the influence of microwave power and gas pressure on the intensity of the emissions. The strong emission of Lyman H2 ≤ft(\\text{B}{}1 Σ u+-\\text{X}{}1 Σ g+\\right) and Werner H2 ≤ft(\\text{C}{}1{{ \\Pi }u}-\\text{X}{}1 Σ g+\\right) molecular bands in the 80-125 nm spectral range was detected, while the most intense atomic emissions observed correspond to Lyman-α and Lyman-β lines at 121.6 nm and 102.6 nm respectively. An increase of the atomic lines and molecular bands intensities with increasing microwave power at pressure 0.1 mbar was observed. At 2 mbar the VUV spectra are entirely dominated by molecular bands. Theoretical predictions, as obtained from a collisional-radiative model, were validated by the experimental results.

  15. Solar Plasma Radio Emission in the Presence of Imbalanced Turbulence of Kinetic-Scale Alfvén Waves

    Science.gov (United States)

    Lyubchyk, O.; Kontar, E. P.; Voitenko, Y. M.; Bian, N. H.; Melrose, D. B.

    2017-09-01

    We study the influence of kinetic-scale Alfvénic turbulence on the generation of plasma radio emission in the solar coronal regions where the ratio β of plasma to magnetic pressure is lower than the electron-to-ion mass ratio me/mi. The present study is motivated by the phenomenon of solar type I radio storms that are associated with the strong magnetic field of active regions. The measured brightness temperature of the type I storms can be up to 10^{10} K for continuum emission, and can exceed 10^{11} K for type I bursts. At present, there is no generally accepted theory explaining such high brightness temperatures and some other properties of the type I storms. We propose a model with an imbalanced turbulence of kinetic-scale Alfvén waves that produce an asymmetric quasi-linear plateau on the upper half of the electron velocity distribution. The Landau damping of resonant Langmuir waves is suppressed and their amplitudes grow spontaneously above the thermal level. The estimated saturation level of Langmuir waves is high enough to generate observed type I radio emission at the fundamental plasma frequency. Harmonic emission does not appear in our model because the backward-propagating Langmuir waves undergo strong Landau damping. Our model predicts 100% polarization in the sense of the ordinary (o-) mode of type I emission.

  16. 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.

  17. Effect of secondary electron emission on nonlinear dust acoustic wave propagation in a complex plasma with negative equilibrium dust charge

    Science.gov (United States)

    Bhakta, Subrata; Ghosh, Uttam; Sarkar, Susmita

    2017-02-01

    In this paper, we have investigated the effect of secondary electron emission on nonlinear propagation of dust acoustic waves in a complex plasma where equilibrium dust charge is negative. The primary electrons, secondary electrons, and ions are Boltzmann distributed, and only dust grains are inertial. Electron-neutral and ion-neutral collisions have been neglected with the assumption that electron and ion mean free paths are very large compared to the plasma Debye length. Both adiabatic and nonadiabatic dust charge variations have been separately taken into account. In the case of adiabatic dust charge variation, nonlinear propagation of dust acoustic waves is governed by the KdV (Korteweg-de Vries) equation, whereas for nonadiabatic dust charge variation, it is governed by the KdV-Burger equation. The solution of the KdV equation gives a dust acoustic soliton, whose amplitude and width depend on the secondary electron yield. Similarly, the KdV-Burger equation provides a dust acoustic shock wave. This dust acoustic shock wave may be monotonic or oscillatory in nature depending on the fact that whether it is dissipation dominated or dispersion dominated. Our analysis shows that secondary electron emission increases nonadiabaticity induced dissipation and consequently increases the monotonicity of the dust acoustic shock wave. Such a dust acoustic shock wave may accelerate charge particles and cause bremsstrahlung radiation in space plasmas whose physical process may be affected by secondary electron emission from dust grains. The effect of the secondary electron emission on the stability of the equilibrium points of the KdV-Burger equation has also been investigated. This equation has two equilibrium points. The trivial equilibrium point with zero potential is a saddle and hence unstable in nature. The nontrivial equilibrium point with constant nonzero potential is a stable node up to a critical value of the wave velocity and a stable focus above it. This critical

  18. Relativistic spherical plasma waves

    Science.gov (United States)

    Bulanov, S. S.; Maksimchuk, A.; Schroeder, C. B.; Zhidkov, A. G.; Esarey, E.; Leemans, W. P.

    2012-02-01

    Tightly focused laser pulses that diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we study theoretically and numerically relativistic spherical wake waves and their properties, including wave breaking.

  19. Magnetoresistive waves in plasmas

    Science.gov (United States)

    Felber, F. S.; Hunter, R. O., Jr.; Pereira, N. R.; Tajima, T.

    1982-10-01

    The self-generated magnetic field of a current diffusing into a plasma between conductors can magnetically insulate the plasma. Propagation of magnetoresistive waves in plasmas is analyzed. Applications to plasma opening switches are discussed.

  20. Relativistic spherical plasma waves

    CERN Document Server

    Bulanov, S S; Schroeder, C B; Zhidkov, A G; Esarey, E; Leemans, W P

    2011-01-01

    Tightly focused laser pulses as they diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we report on theoretical study of relativistic spherical wake waves and their properties, including wave breaking. These waves may be suitable as particle injectors or as flying mirrors that both reflect and focus radiation, enabling unique X-ray sources and nonlinear QED phenomena.

  1. 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.

  2. Cyclotron waves in plasma

    CERN Document Server

    Lominadze, D G

    2013-01-01

    Cyclotron Waves in Plasma is a four-chapter text that covers the basic physical concepts of the theory of cyclotron waves and cyclotron instabilities, brought about by the existence of steady or alternating plasma currents flowing perpendicular to the magnetic field.This book considers first a wide range of questions associated with the linear theory of cyclotron oscillations in equilibrium plasmas and in electron plasmas in metals and semiconductors. The next chapter deals with the parametric excitation of electron cyclotron oscillations in plasma in an alternating electric field. A chapter f

  3. Solar system plasma waves

    Science.gov (United States)

    Gurnett, Donald A.

    1995-01-01

    An overview is given of spacecraft observations of plasma waves in the solar system. In situ measurements of plasma phenomena have now been obtained at all of the planets except Mercury and Pluto, and in the interplanetary medium at heliocentric radial distances ranging from 0.29 to 58 AU. To illustrate the range of phenomena involved, we discuss plasma waves in three regions of physical interest: (1) planetary radiation belts, (2) planetary auroral acceleration regions and (3) the solar wind. In each region we describe examples of plasma waves that are of some importance, either due to the role they play in determining the physical properties of the plasma, or to the unique mechanism involved in their generation.

  4. Induced emission of Alfvén waves in inhomogeneous streaming plasma: implications for solar corona heating and solar wind acceleration.

    Science.gov (United States)

    Galinsky, V L; Shevchenko, V I

    2013-07-05

    The results of a self-consistent kinetic model of heating the solar corona and accelerating the fast solar wind are presented for plasma flowing in a nonuniform magnetic field configuration of near-Sun conditions. The model is based on a scale separation between the large transit or inhomogeneity scales and the small dissipation scales. The macroscale instability of the marginally stable particle distribution function compliments the resonant frequency sweeping dissipation of transient Alfvén waves by their induced emission in inhomogeneous streaming plasma that provides enough energy for keeping the plasma temperature decaying not faster than r(-1) in close agreement with in situ heliospheric observations.

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

    Energy Technology Data Exchange (ETDEWEB)

    Dzierzega, K [Marian Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Cracow (Poland); Pokrzywka, B [Mt. Suhora Observatory, Cracow Pedagogical University, ul. Podchorazych 2, 30-083 Cracow (Poland); Pellerin, S [LASEP, Universite d' Orleans-Centre Universitaire de Bourges, Rue Gaston Berger BP 4043, 18028 Bourges (France)

    2004-07-07

    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.

  6. 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.

  7. Undamped electrostatic plasma waves

    CERN Document Server

    Valentini, F; Califano, F; Pegoraro, F; Veltri, P; Morrison, P J; O'Neil, T M

    2015-01-01

    Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named {\\it corner modes}. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the $(k,\\omega_{_R})$ plane ($\\omega_{_R}$ being the real part of the wave frequency and $k$ the wavenumber), away from the well-known `thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existenc...

  8. Surface wave plasma abatement of CHF{sub 3} and CF{sub 4} containing semiconductor process emissions

    Energy Technology Data Exchange (ETDEWEB)

    Wofford, B.A.; Jackson, M.W. [Rf Environmental Systems, Inc., Seabrook, TX (United States); Hartz, C.; Bevan, J.W. [Texas A and M Univ., College Station, TX (United States). Dept. of Chemistry

    1999-06-01

    Projected exponential growth in semiconductor device manufacture over the next few years demands technology to reduce the corresponding increase in etchants such as perfluorocompounds (PFCs), CHF{sub 3}, and SF{sub 6} that would be emitted into the atmosphere. These compounds are a cause for concern because of their large global warming potentials relative to CO{sub 2} and of their long lifetimes in the atmosphere, often tens of thousands of years. The authors demonstrate that a plasma-based technology can yield effective destruction and removal efficiencies (DREs) for CF{sub 4} and CHF{sub 3} present in etch recipes widely used in the semiconductor industry. Specifically, they report application of surface wave plasmas at 2.45 GHz for this purpose. Post-plasma effluent analysis included the determination of DREs and product distributions, simultaneously by gas-phase FTIR and QMS. Application of microwave powers from 500 to 1950 W were investigated and DREs for CF{sub 4} and CHF{sub 3} reported. Final product analysis indicated that PFC conversion was limited to low molecular weight gases such as CO{sub 2}, CO, COF{sub 2}, H{sub 2}O, and HF. These investigations demonstrate that surface wave plasma destruction of the referenced PFCs at the output of semiconductor etch tools is a viable nonintrusive point of use abatement technology.

  9. Wave turbulence in magnetized plasmas

    Directory of Open Access Journals (Sweden)

    S. Galtier

    2009-02-01

    Full Text Available The paper reviews the recent progress on wave turbulence for magnetized plasmas (MHD, Hall MHD and electron MHD in the incompressible and compressible cases. The emphasis is made on homogeneous and anisotropic turbulence which usually provides the best theoretical framework to investigate space and laboratory plasmas. The solar wind and the coronal heating problems are presented as two examples of application of anisotropic wave turbulence. The most important results of wave turbulence are reported and discussed in the context of natural and simulated magnetized plasmas. Important issues and possible spurious interpretations are also discussed.

  10. Nonlinear plasma wave in magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Bulanov, Sergei V. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Prokhorov Institute of General Physics, Russian Academy of Sciences, Moscow 119991 (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region 141700 (Russian Federation); Esirkepov, Timur Zh.; Kando, Masaki; Koga, James K. [Kansai Photon Science Institute, JAEA, Kizugawa, Kyoto 619-0215 (Japan); Hosokai, Tomonao; Zhidkov, Alexei G. [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan); Japan Science and Technology Agency, CREST, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Kodama, Ryosuke [Photon Pioneers Center, Osaka University, 2-8 Yamadaoka, Suita, Osaka 565-0871 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2013-08-15

    Nonlinear axisymmetric cylindrical plasma oscillations in magnetized collisionless plasmas are a model for the electron fluid collapse on the axis behind an ultrashort relativisically intense laser pulse exciting a plasma wake wave. We present an analytical description of the strongly nonlinear oscillations showing that the magnetic field prevents closing of the cavity formed behind the laser pulse. This effect is demonstrated with 3D PIC simulations of the laser-plasma interaction. An analysis of the betatron oscillations of fast electrons in the presence of the magnetic field reveals a characteristic “Four-Ray Star” pattern.

  11. Waves and instabilities in plasmas

    CERN Document Server

    Chen Liu

    1987-01-01

    The topics covered in these notes are selective and tend to emphasize more on kinetic-theory approaches to waves and instabilities in both uniform and non-uniform plasmas, students are assumed to have some basic knowledge of plasma dynamics in terms of single-particle and fluid descriptions.

  12. A simple electron plasma wave

    Energy Technology Data Exchange (ETDEWEB)

    Brodin, G., E-mail: gert.brodin@physics.umu.se [Department of Physics, Umeå University, SE-901 87 Umeå (Sweden); Stenflo, L. [Department of Physics, Linköping University, SE-581 83 Linköping (Sweden)

    2017-03-18

    Considering a class of solutions where the density perturbations are functions of time, but not of space, we derive a new exact large amplitude wave solution for a cold uniform electron plasma. This result illustrates that most simple analytical solutions can appear even if the density perturbations are large. - Highlights: • The influence of large amplitude electromagnetic waves on electrostatic oscillations is found. • A generalized Mathieu equation is derived. • Anharmonic wave profiles are computed numerically.

  13. 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.

  14. Nonlinear Plasma Wave in Magnetized Plasmas

    CERN Document Server

    Bulanov, Sergei V; Kando, Masaki; Koga, James K; Hosokai, Tomonao; Zhidkov, Alexei G; Kodama, Ryosuke

    2013-01-01

    Nonlinear axisymmetric cylindrical plasma oscillations in magnetized collisionless plasmas are a model for the electron fluid collapse on the axis behind an ultrashort relativisically intense laser pulse exciting a plasma wake wave. We present an analytical description of the strongly nonlinear oscillations showing that the magnetic field prevents closing of the cavity formed behind the laser pulse. This effect is demonstrated with 3D PIC simulations of the laser-plasma interaction. An analysis of the betatron oscillations of fast electrons in the presence of the magnetic field reveals a characteristic "Four-Ray Star" pattern which has been observed in the image of the electron bunch in experiments [T. Hosokai, et al., Phys. Rev. Lett. 97, 075004 (2006)].

  15. A simple electron plasma wave

    Science.gov (United States)

    Brodin, G.; Stenflo, L.

    2017-03-01

    Considering a class of solutions where the density perturbations are functions of time, but not of space, we derive a new exact large amplitude wave solution for a cold uniform electron plasma. This result illustrates that most simple analytical solutions can appear even if the density perturbations are large.

  16. Ion Acoustic Waves in the Presence of Electron Plasma Waves

    DEFF Research Database (Denmark)

    Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens

    1977-01-01

    Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave.......Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave....

  17. KINETIC THEORY OF PLASMA WAVES: Part II: Homogeneous Plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2010-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold

  18. Kinetic theory of plasma waves: Part II homogeneous plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2000-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold

  19. Kinetic theory of plasma waves - Part II: Homogeneous plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2008-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves axe discussed in the limit of the cold

  20. Kinetic theory of plasma waves: Part II homogeneous plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2000-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold

  1. KINETIC THEORY OF PLASMA WAVES: Part II: Homogeneous Plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2010-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold

  2. Kinetic theory of plasma waves - Part II: Homogeneous plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2008-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves axe discussed in the limit of the cold

  3. Electron waves and resonances in bounded plasmas

    CERN Document Server

    Vandenplas, Paul E

    1968-01-01

    General theoretical methods and experimental techniques ; the uniform plasma slab-condenser system ; the hollow cylindrical plasma ; scattering of a plane electromagnetic wave by a plasma column in steady magnetic fields (cold plasma approximation) ; hot non-uniform plasma column ; metallic and dielectric resonance probes, plasma-dielectric coated antenna, general considerations.

  4. Excitation of Chirping Whistler Waves in a Laboratory Plasma

    Science.gov (United States)

    Van Compernolle, B.; An, X.; Bortnik, J.; Thorne, R. M.; Gekelman, W. N.; Pribyl, P.

    2015-12-01

    Whistler mode chorus emissions with a characteristic frequency chirp are an important magnetospheric wave, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Here, we report on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced using a beam of energetic electrons launched into a cold plasma. Frequency chirps are only observed for a narrow range of plasma and beam parameters, and show a strong dependence on beam density, plasma density and magnetic field gradient. Broadband whistler waves similar to magnetospheric hiss are also observed, and the parameter ranges for each emission are quantified. The research was funded by NSF/DOE Plasma Partnership program by grant DE-SC0010578. Work was done at the Basic Plasma Science Facility (BAPSF) also funded by NSF/DOE.

  5. 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

  6. Plasma Waves and Jets from Moving Conductors

    CERN Document Server

    Gralla, Samuel E

    2016-01-01

    We consider force-free plasma waves launched by the motion of conducting material through a magnetic field. We develop a spacetime-covariant formalism for perturbations of a uniform magnetic field and show how the transverse motion of a conducting fluid acts as a source. We show that fast-mode waves are sourced by the compressibility of the fluid, with incompressible fluids launching a pure-Alfven outflow. Remarkably, this outflow can be written down in closed form, at the nonlinear level, for an arbitrary incompressible flow. The instantaneous flow velocity is imprinted on the magnetic field and transmitted away at the speed of light, carrying detailed information about the conducting source at the time of emission. These results can be applied to transients in pulsar outflows and to jets from neutron stars orbiting in the magnetosphere of another compact object. We discuss jets from moving conductors in some detail.

  7. Drift wave in pair-ion plasma

    Indian Academy of Sciences (India)

    Samiran Ghosh; Nikhil Chakrabarti; Manoranjan Khan; M R Gupta

    2013-02-01

    The conditions for the existence of low-frequency electrostatic drift wave in pair-ion plasma are discussed. It is shown that the temperature and/or mass difference of both species could produce drift wave in a pair-ion plasma. The results are discussed in the context of the fullerene pair-ion plasma experiment.

  8. Relativistic electron scattering by magnetosonic waves: Effects of discrete wave emission and high wave amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Artemyev, A. V., E-mail: ante0226@gmail.com [Space Research Institute, RAS, Moscow (Russian Federation); Mourenas, D.; Krasnoselskikh, V. V. [LPC2E/CNRS - University of Orleans, Orleans (France); Agapitov, O. V. [Space Sciences Laboratory, University of California, Berkeley, California 94720 (United States)

    2015-06-15

    In this paper, we study relativistic electron scattering by fast magnetosonic waves. We compare results of test particle simulations and the quasi-linear theory for different spectra of waves to investigate how a fine structure of the wave emission can influence electron resonant scattering. We show that for a realistically wide distribution of wave normal angles θ (i.e., when the dispersion δθ≥0.5{sup °}), relativistic electron scattering is similar for a wide wave spectrum and for a spectrum consisting in well-separated ion cyclotron harmonics. Comparisons of test particle simulations with quasi-linear theory show that for δθ>0.5{sup °}, the quasi-linear approximation describes resonant scattering correctly for a large enough plasma frequency. For a very narrow θ distribution (when δθ∼0.05{sup °}), however, the effect of a fine structure in the wave spectrum becomes important. In this case, quasi-linear theory clearly fails in describing accurately electron scattering by fast magnetosonic waves. We also study the effect of high wave amplitudes on relativistic electron scattering. For typical conditions in the earth's radiation belts, the quasi-linear approximation cannot accurately describe electron scattering for waves with averaged amplitudes >300 pT. We discuss various applications of the obtained results for modeling electron dynamics in the radiation belts and in the Earth's magnetotail.

  9. Dichromatic Langmuir waves in degenerate quantum plasma

    Science.gov (United States)

    Dubinov, A. E.; Kitayev, I. N.

    2015-06-01

    Langmuir waves in fully degenerate quantum plasma are considered. It is shown that, in the linear approximation, Langmuir waves are always dichromatic. The low-frequency component of the waves corresponds to classical Langmuir waves, while the high-frequency component, to free-electron quantum oscillations. The nonlinear problem on the profile of dichromatic Langmuir waves is solved. Solutions in the form of a superposition of waves and in the form of beatings of its components are obtained.

  10. Material measurement method based on femtosecond laser plasma shock wave

    Science.gov (United States)

    Zhong, Dong; Li, Zhongming

    2017-03-01

    The acoustic emission signal of laser plasma shock wave, which comes into being when femtosecond laser ablates pure Cu, Fe, and Al target material, has been detected by using the fiber Fabry-Perot (F-P) acoustic emission sensing probe. The spectrum characters of the acoustic emission signals for three kinds of materials have been analyzed and studied by using Fourier transform. The results show that the frequencies of the acoustic emission signals detected from the three kinds of materials are different. Meanwhile, the frequencies are almost identical for the same materials under different ablation energies and detection ranges. Certainly, the amplitudes of the spectral character of the three materials show a fixed pattern. The experimental results and methods suggest a potential application of the plasma shock wave on-line measurement based on the femtosecond laser ablating target by using the fiber F-P acoustic emission sensor probe.

  11. Regimes of enhanced electromagnetic emission in beam-plasma interactions

    Energy Technology Data Exchange (ETDEWEB)

    Timofeev, I. V.; Annenkov, V. V.; Arzhannikov, A. V. [Budker Institute of Nuclear Physics, SB RAS, 630090 Novosibirsk, Russia and Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2015-11-15

    The ways to improve the efficiency of electromagnetic waves generation in laboratory experiments with high-current relativistic electron beams injected into a magnetized plasma are discussed. It is known that such a beam can lose, in a plasma, a significant part of its energy by exciting a high level of turbulence and heating plasma electrons. Beam-excited plasma oscillations may simultaneously participate in nonlinear processes resulting in a fundamental and second harmonic emissions. It is obvious, however, that in the developed plasma turbulence the role of these emissions in the total energy balance is always negligible. In this paper, we investigate whether electromagnetic radiation generated in the beam-plasma system can be sufficiently enhanced by the direct linear conversion of resonant beam-driven modes into electromagnetic ones on preformed regular inhomogeneities of plasma density. Due to the high power of relativistic electron beams, the mechanism discussed may become the basis for the generator of powerful sub-terahertz radiation.

  12. Regimes of enhanced electromagnetic emission in beam-plasma interactions

    Science.gov (United States)

    Timofeev, I. V.; Annenkov, V. V.; Arzhannikov, A. V.

    2015-11-01

    The ways to improve the efficiency of electromagnetic waves generation in laboratory experiments with high-current relativistic electron beams injected into a magnetized plasma are discussed. It is known that such a beam can lose, in a plasma, a significant part of its energy by exciting a high level of turbulence and heating plasma electrons. Beam-excited plasma oscillations may simultaneously participate in nonlinear processes resulting in a fundamental and second harmonic emissions. It is obvious, however, that in the developed plasma turbulence the role of these emissions in the total energy balance is always negligible. In this paper, we investigate whether electromagnetic radiation generated in the beam-plasma system can be sufficiently enhanced by the direct linear conversion of resonant beam-driven modes into electromagnetic ones on preformed regular inhomogeneities of plasma density. Due to the high power of relativistic electron beams, the mechanism discussed may become the basis for the generator of powerful sub-terahertz radiation.

  13. Observation of nonlinear wave decay processes in the solar wind by the AMPTE IRM plasma wave experiment

    Science.gov (United States)

    Koons, H. C.; Roeder, J. L.; Bauer, O. H.; Haerendel, G.; Treumann, R.

    1987-01-01

    Nonlinear wave decay processes have been detected in the solar wind by the plasma wave experiment aboard the Active Magnetospheric Particle Tracer Explorers (AMPTE) IRM spacecraft. The main process is the generation of ultralow-frequency ion acoustic waves from the decay of Langmuir waves near the electron plasma frequency. Frequently, this is accompanied by an enhancement of emissions near twice the plasma frequency. This enhancement is most likely due to the generation of electromagnetic waves from the coalescence of two Langmuir waves. These processes occur within the electron foreshock in front of the earth's bow shock.

  14. Low-Frequency Waves in Space Plasmas

    Science.gov (United States)

    Keiling, Andreas; Lee, Dong-Hun; Nakariakov, Valery

    2016-02-01

    Low-frequency waves in space plasmas have been studied for several decades, and our knowledge gain has been incremental with several paradigm-changing leaps forward. In our solar system, such waves occur in the ionospheres and magnetospheres of planets, and around our Moon. They occur in the solar wind, and more recently, they have been confirmed in the Sun's atmosphere as well. The goal of wave research is to understand their generation, their propagation, and their interaction with the surrounding plasma. Low-frequency Waves in Space Plasmas presents a concise and authoritative up-to-date look on where wave research stands: What have we learned in the last decade? What are unanswered questions? While in the past waves in different astrophysical plasmas have been largely treated in separate books, the unique feature of this monograph is that it covers waves in many plasma regions, including: Waves in geospace, including ionosphere and magnetosphere Waves in planetary magnetospheres Waves at the Moon Waves in the solar wind Waves in the solar atmosphere Because of the breadth of topics covered, this volume should appeal to a broad community of space scientists and students, and it should also be of interest to astronomers/astrophysicists who are studying space plasmas beyond our Solar System.

  15. Plasma Waves as a Benchmark Problem

    CERN Document Server

    Kilian, Patrick; Schreiner, Cedric; Spanier, Felix

    2016-01-01

    A large number of wave modes exist in a magnetized plasma. Their properties are determined by the interaction of particles and waves. In a simulation code, the correct treatment of field quantities and particle behavior is essential to correctly reproduce the wave properties. Consequently, plasma waves provide test problems that cover a large fraction of the simulation code. The large number of possible wave modes and the freedom to choose parameters make the selection of test problems time consuming and comparison between different codes difficult. This paper therefore aims to provide a selection of test problems, based on different wave modes and with well defined parameter values, that is accessible to a large number of simulation codes to allow for easy benchmarking and cross validation. Example results are provided for a number of plasma models. For all plasma models and wave modes that are used in the test problems, a mathematical description is provided to clarify notation and avoid possible misunderst...

  16. Excitation of Chirping Whistler Waves in a Laboratory Plasma.

    Science.gov (United States)

    Van Compernolle, B; An, X; Bortnik, J; Thorne, R M; Pribyl, P; Gekelman, W

    2015-06-19

    Whistler mode chorus emissions with a characteristic frequency chirp are important magnetospheric waves, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Here, we report on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced using a beam of energetic electrons launched into a cold plasma. Frequency chirps are only observed for a narrow range of plasma and beam parameters, and show a strong dependence on beam density, plasma density, and magnetic field gradient. Broadband whistler waves similar to magnetospheric hiss are also observed, and the parameter ranges for each emission are quantified.

  17. Electromagnetic waves in a strong Schwarzschild plasma

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, J.; Tajima, T.

    1996-11-01

    The physics of high frequency electromagnetic waves in a general relativistic plasma with the Schwarzschild metric is studied. Based on the 3 + 1 formalism, we conformalize Maxwell`s equations. The derived dispersion relations for waves in the plasma contain the lapse function in the plasma parameters such as in the plasma frequency and cyclotron frequency, but otherwise look {open_quotes}flat.{close_quotes} Because of this property this formulation is ideal for nonlinear self-consistent particle (PIC) simulation. Some of the physical consequences arising from the general relativistic lapse function as well as from the effects specific to the plasma background distribution (such as density and magnetic field) give rise to nonuniform wave equations and their associated phenomena, such as wave resonance, cutoff, and mode-conversion. These phenomena are expected to characterize the spectroscopy of radiation emitted by the plasma around the black hole. PIC simulation results of electron-positron plasma are also presented.

  18. Electron beam generated whistler emissions in a laboratory plasma

    Energy Technology Data Exchange (ETDEWEB)

    Van Compernolle, B., E-mail: bvcomper@physics.ucla.edu; Pribyl, P.; Gekelman, W. [Department of Physics, University of California, Los Angeles (United States); An, X.; Bortnik, J.; Thorne, R. M. [Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles (United States)

    2015-12-10

    Naturally occurring whistler mode emissions in the magnetosphere, are important since they are responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Recently, we reported on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced [1]. A beam of energetic electrons is launched into a cold plasma and excites both chirping whistler waves and broadband waves. Here we extend our previous analysis by comparing the properties of the broadband waves with linear theory.

  19. Electron beam generated whistler emissions in a laboratory plasma

    Science.gov (United States)

    Van Compernolle, B.; An, X.; Bortnik, J.; Thorne, R. M.; Pribyl, P.; Gekelman, W.

    2015-12-01

    Naturally occurring whistler mode emissions in the magnetosphere, are important since they are responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. Recently, we reported on the first laboratory experiment where whistler waves exhibiting fast frequency chirping have been artificially produced [1]. A beam of energetic electrons is launched into a cold plasma and excites both chirping whistler waves and broadband waves. Here we extend our previous analysis by comparing the properties of the broadband waves with linear theory.

  20. Saturation of Langmuir waves in laser-produced plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Baker, K.L.

    1996-04-01

    This dissertation deals with the interaction of an intense laser with a plasma (a quasineutral collection of electrons and ions). During this interaction, the laser drives large-amplitude waves through a class of processes known as parametric instabilities. Several such instabilities drive one type of wave, the Langmuir wave, which involves oscillations of the electrons relative to the nearly-stationary ions. There are a number of mechanisms which limit the amplitude to which Langmuir waves grow. In this dissertation, these mechanisms are examined to identify qualitative features which might be observed in experiments and/or simulations. In addition, a number of experiments are proposed to specifically look for particular saturation mechanisms. In a plasma, a Langmuir wave can decay into an electromagnetic wave and an ion wave. This parametric instability is proposed as a source for electromagnetic emission near half of the incident laser frequency observed from laser-produced plasmas. This interpretation is shown to be consistent with existing experimental data and it is found that one of the previous mechanisms used to explain such emission is not. The scattering version of the electromagnetic decay instability is shown to provide an enhanced noise source of electromagnetic waves near the frequency of the incident laser.

  1. Solitary Waves in Relativistic Electromagnetic Plasma

    Institute of Scientific and Technical Information of China (English)

    XIE Bai-Song; HUA Cun-Cai

    2005-01-01

    Solitary waves in relativistic electromagnetic plasmas are obtained numerically. The longitudinal momentum of electrons has been taken into account in the problem. It is found that in the moving frame with electromagnetic field propagating the solitary waves can exist in both cases, where the vector potential frequency is larger or smaller than the plasma characteristic frequency.

  2. Electron beam injection during active experiments. I - Electromagnetic wave emissions

    Science.gov (United States)

    Winglee, R. M.; Kellogg, P. J.

    1990-01-01

    The wave emissions produced in Echo 7 experiment by active injections of electron beams were investigated to determine the properties of the electromagnetic and electrostatic fields for both the field-aligned and cross-field injection in such experiments and to evaluate the sources of free energy and relative efficiencies for the generation of the VLF and HF emissions. It is shown that, for typical beam energies in active experiments, electromagnetic effects do not substantially change the bulk properties of the beam, spacecraft charging, and plasma particle acceleration. Through simulations, beam-generated whistlers; fundamental z-mode and harmonic x-mode radiation; and electrostatic electron-cyclotron, upper-hybrid, Langmuir, and lower-hybrid waves were identified. The characteristics of the observed wave spectra were found to be sensitive to both the ratio of the electron plasma frequency to the cyclotron frequency and the angle of injection relative to the magnetic field.

  3. Damping of Slow Magnetoacoustic Waves in an Inhomogeneous Coronal Plasma

    Indian Academy of Sciences (India)

    Nagendra Kumar; Pradeep Kumar; Shiv Singh; Anil Kumar

    2008-03-01

    We study the propagation and dissipation of slow magnetoacoustic waves in an inhomogeneous viscous coronal loop plasma permeated by uniform magnetic field. Only viscosity and thermal conductivity are taken into account as dissipative processes in the coronal loop. The damping length of slow-mode waves exhibit varying behaviour depending upon the physical parameters of the loop in an active region AR8270 observed by TRACE. The wave energy flux associated with slow magnetoacoustic waves turns out to be of the order of 106 erg cm-2 s-1 which is high enough to replace the energy lost through optically thin coronal emission and the thermal conduction belowto the transition region. It is also found that only those slow-mode waves which have periods more than 240 s provide the required heating rate to balance the energy losses in the solar corona. Our calculated wave periods for slow-mode waves nearly match with the oscillation periods of loop observed by TRACE.

  4. Alfven Wave Tomography for Cold MHD Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    I.Y. Dodin; N.J. Fisch

    2001-09-07

    Alfven waves propagation in slightly nonuniform cold plasmas is studied by means of ideal magnetohydrodynamics (MHD) nonlinear equations. The evolution of the MHD spectrum is shown to be governed by a matrix linear differential equation with constant coefficients determined by the spectrum of quasi-static plasma density perturbations. The Alfven waves are shown not to affect the plasma density inhomogeneities, as they scatter off of them. The application of the MHD spectrum evolution equation to the inverse scattering problem allows tomographic measurements of the plasma density profile by scanning the plasma volume with Alfven radiation.

  5. Analysis of plasma waves observed in the inner Saturn magnetosphere

    Directory of Open Access Journals (Sweden)

    J. D. Menietti

    2008-09-01

    Full Text Available Plasma waves observed in the Saturn magnetosphere provide an indication of the plasma population present in the rotationally dominated inner magnetosphere. Electrostatic cyclotron emissions often with harmonics and whistler mode emission are a common feature of Saturn's inner magnetosphere. The electron observations for a region near 5 RS outside and near a plasma injection region indicate a cooler low-energy (<100 eV, nearly isotropic plasma, and a much warmer (E>1000 eV more pancake or butterfly distribution. We model the electron plasma distributions to conduct a linear dispersion analysis of the wave modes. The results suggest that the electrostatic electron cyclotron emissions can be generated by phase space density gradients associated with a loss cone that may be up to 20° wide. This loss cone is sometimes, but not always, observed because the field of view of the electron detectors does not include the magnetic field line at the time of the observations. The whistler mode emission can be generated by the pancake-like distribution and temperature anisotropy (T/T||>1 of the warmer plasma population.

  6. Stress wave emission from plasmonic nanobubbles

    Science.gov (United States)

    Brujan, Emil-Alexandru

    2017-01-01

    Stress wave emission from the collapse of cavitation nanobubbles, generated after irradiation of single-spherical gold nanoparticles with laser pulses, was investigated numerically. The significant parameters of this study are the nanoparticle radius, laser pulse duration, and laser fluence. For conditions comparable to those existing during plasmonic photothermal therapy, a purely compressive pressure wave is emitted during nanobubble collapse, not a shock. In the initial stage of its propagation, the stress wave amplitude is proportional to the inverse of the stress wave radius. The maximum amplitude and the duration of the stress wave decreases with the laser fluence, laser pulse duration, and gold nanoparticle radius. The full width at half maximum duration of the stress wave is almost constant up to a distance of 50 µm from the emission center. The stress wave amplitude is smaller than 5 MPa, while the stress wave duration is smaller than 35 ns. The stress wave propagation results in minor mechanical effects on biological tissue that are restricted to very small dimensions on a cellular or sub-cellular level. The stress wave is, however, able to produce breaching of the human cell membrane and bacterial wall even at distances as large as 50 µm from the emission centre. The experimentally observed melting of gold nanoparticles comes from the large temperature reached inside the nanoparticles during laser irradiation and not from the propagation of the stress wave into the surrounding liquid during nanobubble rebound.

  7. Wave-driven Countercurrent Plasma Centrifuge

    Energy Technology Data Exchange (ETDEWEB)

    A.J. Fetterman and N.J. Fisch

    2009-03-20

    A method for driving rotation and a countercurrent flow in a fully ionized plasma centrifuge is described. The rotation is produced by radiofrequency waves near the cyclotron resonance. The wave energy is transferred into potential energy in a manner similar to the α channeling effect. The countercurrent flow may also be driven by radiofrequency waves. By driving both the rotation and the flow pattern using waves instead of electrodes, physical and engineering issues may be avoided.

  8. Effect of wave localization on plasma instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Levedahl, W.K.

    1987-01-01

    The Anderson model of wave localization in random media is invoked to study the effect of solar-wind density turbulence on plasma processes associated with the solar type-III radio burst. ISEE-3 satellite data indicate that a possible model for the type-III process is the parametric decay of Langmuir waves excited by solar-flare electron streams into daughter electromagnetic and ion-acoustic waves. The threshold for this instability, however, is much higher than observed Langmuir-wave levels because of rapid wave convection of the transverse electromagnetic daughter wave in the case where the solar wind is assumed homogeneous. Langmuir and transverse waves near critical density satisfy the Ioffe-Riegel criteria for wave localization in the solar wind with observed density fluctuations {approximately}1%. Computer simulations using a linearized hybrid code show that an electron beam will excite localized Langmuir waves in a plasma with density turbulence. An action-principle approach is used to develop a theory of nonlinear wave processes when waves are localized. A theory of resonant particles diffusion by localized waves is developed to explain the saturation of the beam-plasma instability.

  9. Evolution Of Nonlinear Waves in Compressing Plasma

    Energy Technology Data Exchange (ETDEWEB)

    P.F. Schmit, I.Y. Dodin, and N.J. Fisch

    2011-05-27

    Through particle-in-cell simulations, the evolution of nonlinear plasma waves is examined in one-dimensional collisionless plasma undergoing mechanical compression. Unlike linear waves, whose wavelength decreases proportionally to the system length L(t), nonlinear waves, such as solitary electron holes, conserve their characteristic size {Delta} during slow compression. This leads to a substantially stronger adiabatic amplification as well as rapid collisionless damping when L approaches {Delta}. On the other hand, cessation of compression halts the wave evolution, yielding a stable mode.

  10. Kinetic Alfven wave turbulence in space plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, R.P. [Plasma Simulation Laboratory, Centre for Energy Studies, Indian Institute of Technology, Delhi-110016, New Delhi (India); Kumar, Sachin, E-mail: dynamicalfven@gmail.co [Plasma Simulation Laboratory, Centre for Energy Studies, Indian Institute of Technology, Delhi-110016, New Delhi (India)

    2010-07-26

    This work presents the derivation of nonlinear coupled equations for the evolution of solar wind turbulence. These equations are governing the coupled dynamics of kinetic Alfven wave and ion acoustic wave. Numerical simulation of these equations is also presented. The ponderomotive nonlinearity is incorporated in the wave dynamics. Filamentation of kinetic Alfven wave and the turbulent spectra are presented in intermediate-{beta} plasmas at heliocentric distances (0.3 AU{<=}r<1.0 AU). The growing filaments and steeper turbulent spectra (of power law k{sup -S}, 5/3{<=}S{<=}3) can be responsible for plasma heating and particle acceleration in solar wind.

  11. Nonlinear Electron Waves in Strongly Magnetized Plasmas

    DEFF Research Database (Denmark)

    Pécseli, Hans; Juul Rasmussen, Jens

    1980-01-01

    dynamics in the analysis is also demonstrated. As a particular case the authors investigate nonlinear waves in a strongly magnetized plasma filled wave-guide, where the effects of finite geometry are important. The relevance of this problem to laboratory experiments is discussed.......Weakly nonlinear dispersive electron waves in strongly magnetized plasma are considered. A modified nonlinear Schrodinger equation is derived taking into account the effect of particles resonating with the group velocity of the waves (nonlinear Landau damping). The possibility of including the ion...

  12. Nonlinear Electrostatic Wave Equations for Magnetized Plasmas

    DEFF Research Database (Denmark)

    Dysthe, K.B.; Mjølhus, E.; Pécseli, Hans

    1984-01-01

    The lowest order kinetic effects are included in the equations for nonlinear electrostatic electron waves in a magnetized plasma. The modifications of the authors' previous analysis based on a fluid model are discussed.......The lowest order kinetic effects are included in the equations for nonlinear electrostatic electron waves in a magnetized plasma. The modifications of the authors' previous analysis based on a fluid model are discussed....

  13. Drift waves in a weakly ionized plasma

    DEFF Research Database (Denmark)

    Popovic, M.; Melchior, H.

    1968-01-01

    A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated.......A dispersion relation for low frequency drift waves in a weakly ionized plasma has been derived, and through numerical calculations the effect of collisions between the charged and the neutral particles is estimated....

  14. Waves in plasmas (part 1 - wave-plasma interaction general background); Ondes dans les plasmas (Partie 1 - interaction onde / plasma: bases physiques)

    Energy Technology Data Exchange (ETDEWEB)

    Dumont, R

    2004-07-01

    This document gathers a series of transparencies presented in the framework of the week-long lectures 'hot plasmas 2004' and dedicated to the physics of wave-plasma interaction. The structure of this document is as follows: 1) wave and diverse plasmas, 2) basic equations (Maxwell equations), 3) waves in a fluid plasma, and 4) waves in a kinetic plasma (collisionless plasma)

  15. Kinetic theory of the interaction of gravitational waves with a plasma

    Energy Technology Data Exchange (ETDEWEB)

    Galtsov, D.V.; Melkumova, E.Iu.

    1983-01-01

    The interaction of weak gravitational waves (GWs) with a plasma is described in terms of kinetic equations and is reduced to the mutual excitation and a energy exchange between the GW, plasmons, and charged particles of the plasma. The approach used is based on elementary quantum considerations, which makes it possible to obtain a closed system of balance equations for the distribution functions of plasma particles, plasmons, and gravitons. The calculation of probabilities included in the balance equations is based on the correspondence principle, which makes it necessary to consider only those processes which accompany gravitational-wave emission. Particular consideration is given to the gravitational susceptibility of the plasma, gravitational-wave generation during the merging of plasma waves, and the 'super-light-speed' Cerenkov emission of gravitational waves from a plasma filament.

  16. Chaotic ion motion in magnetosonic plasma waves

    Science.gov (United States)

    Varvoglis, H.

    1984-01-01

    The motion of test ions in a magnetosonic plasma wave is considered, and the 'stochasticity threshold' of the wave's amplitude for the onset of chaotic motion is estimated. It is shown that for wave amplitudes above the stochasticity threshold, the evolution of an ion distribution can be described by a diffusion equation with a diffusion coefficient D approximately equal to 1/v. Possible applications of this process to ion acceleration in flares and ion beam thermalization are discussed.

  17. Second harmonic wave generation from a nonlinear combination of volume wave and overdense plasma in negative permeability space

    Science.gov (United States)

    Iwai, Akinori; Nakamura, Yoshihiro; Sakai, Osamu

    2016-09-01

    We clarify the relation between second harmonic wave (SH wave) and plasma generation in various experimental conditions by detecting properties of propagating electromagnetic waves (EM waves). Plasma has a nonlinear reaction against EM wave, generating harmonic waves which depends on electron density ne. In the case with increased ne, EM wave comes to be prevented from going into plasma with negative permittivity ɛp. Double-split-ring resonators (DSRRs), one of metamaterials, make permeability μD negative. We have shown that EM wave being volume wave can propagate into the combination of overdense plasma and DSRRs because of real negative value refractive index N. In our previous paper, we have confirmed enhanced SH wave (4.9 GHz) generation in the composite with 2.45-GHz input. In this report, we show the dependence of the SH wave emission with plasma generation on plasma parameters and gas conditions of plasma. Furthermore, we show the phase change with N variation of the composite space in the case with various input power as the proof of the negative index state.

  18. Weakly nonlinear electron plasma waves in collisional plasmas

    DEFF Research Database (Denmark)

    Pecseli, H. L.; Rasmussen, J. Juul; Tagare, S. G.

    1986-01-01

    The nonlinear evolution of a high frequency plasma wave in a weakly magnetized, collisional plasma is considered. In addition to the ponderomotive-force-nonlinearity the nonlinearity due to the heating of the electrons is taken into account. A set of nonlinear equations including the effect...... of a constantly maintained pump wave is derived and a general dispersion relation describing the modulation of the high frequency wave due to different low frequency responses is obtained. Particular attention is devoted to a purely growing modulation. The relative importance of the ponderomotive force...

  19. Generalized Langmuir Waves in Magnetized Kinetic Plasmas

    Science.gov (United States)

    Willes, A. J.; Cairns, Iver H.

    2000-01-01

    The properties of unmagnetized Langmuir waves and cold plasma magnetoionic waves (x, o, z and whistler) are well known. However, the connections between these modes in a magnetized kinetic plasma have not been explored in detail. Here, wave properties are investigated by numerically solving the dispersion equation derived from the Vlasov equations both with and without a beam instability present. For omega(sub p)>Omega(sub e), it is shown that the generalized Langmuir mode at oblique propagation angles has magnetic z-mode characteristics at low wave numbers and thermal Langmuir mode characteristics at high wave numbers. For omega(sub p)Langmuir mode instead connects to the whistler mode at low wave numbers. The transition from the Langmuir/z mode to the Langmuir/whistler mode near omega(sub p) = Omega(sub e) is rapid. In addition, the effects on wave dispersion and polarization after adding a beam are investigated. Applications of this theory to magnetized Langmuir waves in Earth's foreshock and the solar wind, to waves observed near the plasma frequency in the auroral regions, and to solar type III bursts are discussed.

  20. Electron plasma waves in the solar wind - AMPTE/IRM and UKS observations

    Science.gov (United States)

    Treumann, R. A.; Bauer, O. H.; Labelle, J.; Haerendel, G.; Christiansen, P. J.

    1986-01-01

    Selected events of plasma wave and electromagnetic emissions in the earth's electron fore-shock region have been studied. Strong emissions are observed in the plasma-wave band when the site of the satellite is magnetically connected to the bow shock. These emissions are generally highly fluctuating. Under certain conditions one observes electromagnetic radiation at the second harmonic produced locally. Electromagnetic emission generated at a position far away from the site of the spacecraft is occasionally detected giving rise to remote sensing of the bow shock. These emissions are related to energetic electron fluxes.

  1. RF wave propagation and scattering in turbulent tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Horton, W., E-mail: wendell.horton@gmail.com; Michoski, C. [Institute for Fusion Studies, The University of Texas at Austin, Austin, TX 78654 (United States); Peysson, Y.; Decker, J. [CEA, IRFM, 13108, Saint-Paul, Durance Cedex (France)

    2015-12-10

    Drift wave turbulence driven by the steep electron and ion temperature gradients in H-mode divertor tokamaks produce scattering of the RF waves used for heating and current drive. The X-ray emission spectra produced by the fast electrons require the turbulence broaden RF wave spectrum. Both the 5 GHz Lower Hybrid waves and the 170 GHz electron cyclotron [EC] RF waves experience scattering and diffraction by the electron density fluctuations. With strong LHCD there are bifurcations in the coupled turbulent transport dynamics giving improved steady-state confinement states. The stochastic scattering of the RF rays makes the prediction of the distribution of the rays and the associated particle heating a statistical problem. Thus, we introduce a Fokker-Planck equation for the probably density of the RF rays. The general frame work of the coupled system of coupled high frequency current driving rays with the low-frequency turbulent transport determines the profiles of the plasma density and temperatures.

  2. Twisted electron-acoustic waves in plasmas

    Science.gov (United States)

    Aman-ur-Rehman, Ali, S.; Khan, S. A.; Shahzad, K.

    2016-08-01

    In the paraxial limit, a twisted electron-acoustic (EA) wave is studied in a collisionless unmagnetized plasma, whose constituents are the dynamical cold electrons and Boltzmannian hot electrons in the background of static positive ions. The analytical and numerical solutions of the plasma kinetic equation suggest that EA waves with finite amount of orbital angular momentum exhibit a twist in its behavior. The twisted wave particle resonance is also taken into consideration that has been appeared through the effective wave number qeff accounting for Laguerre-Gaussian mode profiles attributed to helical phase structures. Consequently, the dispersion relation and the damping rate of the EA waves are significantly modified with the twisted parameter η, and for η → ∞, the results coincide with the straight propagating plane EA waves. Numerically, new features of twisted EA waves are identified by considering various regimes of wavelength and the results might be useful for transport and trapping of plasma particles in a two-electron component plasma.

  3. VLF emissions from ionospheric/magnetospheric plasma

    Indian Academy of Sciences (India)

    R P Patel; R P Singh

    2001-05-01

    VLF emissions such as hiss, chorus, oscillating tones, hiss-triggered chorus and whistler triggered emissions have been observed at low latitude Indian stations. In this paper we present dynamic spectra of these emissions and discuss their various observed features. It is argued that most of the emissions are generated during Doppler shifted cyclotron resonance interaction between the whistler mode wave and counter streaming energetic electrons. Resonance energy of the participating electron and interaction length are evaluated to explain the generation mechanism of some of these emissions observed at Indian stations.

  4. Colliding solitary waves in quark gluon plasmas

    Science.gov (United States)

    Rafiei, Azam; Javidan, Kurosh

    2016-09-01

    We study the head-on collision of propagating waves due to perturbations in quark gluon plasmas. We use the Massachusetts Institute of Technology bag model, hydrodynamics equation, and suitable equation of state for describing the time evolution of such localized waves. A nonlinear differential equation is derived for the propagation of small amplitude localized waves using the reductive perturbation method. We show that these waves are unstable and amplitude of the left-moving (right-moving) wave increases (decreases) after the collision, and so they reach the borders of a quark gluon plasma fireball with different amplitudes. Indeed we show that such arrangements are created because of the geometrical symmetries of the medium.

  5. First results from the Cluster wideband plasma wave investigation

    Directory of Open Access Journals (Sweden)

    D. A. Gurnett

    Full Text Available In this report we present the first results from the Cluster wideband plasma wave investigation. The four Cluster spacecraft were successfully placed in closely spaced, high-inclination eccentric orbits around the Earth during two separate launches in July – August 2000. Each spacecraft includes a wideband plasma wave instrument designed to provide high-resolution electric and magnetic field wave-forms via both stored data and direct downlinks to the NASA Deep Space Network. Results are presented for three commonly occurring magnetospheric plasma wave phenomena: (1 whistlers, (2 chorus, and (3 auroral kilometric radiation. Lightning-generated whistlers are frequently observed when the spacecraft is inside the plasmasphere. Usually the same whistler can be detected by all spacecraft, indicating that the whistler wave packet extends over a spatial dimension at least as large as the separation distances transverse to the magnetic field, which during these observations were a few hundred km. This is what would be expected for nonducted whistler propagation. No case has been found in which a strong whistler was detected at one spacecraft, with no signal at the other spacecraft, which would indicate ducted propagation. Whistler-mode chorus emissions are also observed in the inner region of the magnetosphere. In contrast to lightning-generated whistlers, the individual chorus elements seldom show a one-to-one correspondence between the spacecraft, indicating that a typical chorus wave packet has dimensions transverse to the magnetic field of only a few hundred km or less. In one case where a good one-to-one correspondence existed, significant frequency variations were observed between the spacecraft, indicating that the frequency of the wave packet may be evolving as the wave propagates. Auroral kilometric radiation, which is an intense radio emission generated along the auroral field lines, is frequently observed over the polar regions. The

  6. Domain Wall Propagation through Spin Wave Emission

    NARCIS (Netherlands)

    Wang, X.S.; Yan, P.; Shen, Y.H.; Bauer, G.E.W.; Wang, X.R.

    2012-01-01

    We theoretically study field-induced domain wall motion in an electrically insulating ferromagnet with hard- and easy-axis anisotropies. Domain walls can propagate along a dissipationless wire through spin wave emission locked into the known soliton velocity at low fields. In the presence of damping

  7. Collapse of nonlinear electron plasma waves in a plasma layer

    Science.gov (United States)

    Grimalsky, V.; Koshevaya, S.; Rapoport, Yu; Kotsarenko, A.

    2016-10-01

    The excitation of nonlinear electron plasma waves in the plasma layer is investigated theoretically. This excitation is realized by means of initial oscillatory perturbations of the volume electron concentration or by initial oscillatory distributions of the longitudinal electron velocity. The amplitudes of the initial perturbations are small and the manifestation of the volume nonlinearity is absent. When the amplitudes of the initial perturbations exceed some thresholds, the values of the electron concentration near the plasma boundary increase catastrophically. The maxima of the electron concentration reach extremely high magnitudes, and sharp peaks in the electron concentration occur, which are localized both in the longitudinal and transverse directions. This effect is interpreted as wave collapse near the plasma boundary.

  8. Shock Wave Dynamics in Weakly Ionized Plasmas

    Science.gov (United States)

    Johnson, Joseph A., III

    1999-01-01

    An investigation of the dynamics of shock waves in weakly ionized argon plasmas has been performed using a pressure ruptured shock tube. The velocity of the shock is observed to increase when the shock traverses the plasma. The observed increases cannot be accounted for by thermal effects alone. Possible mechanisms that could explain the anomalous behavior include a vibrational/translational relaxation in the nonequilibrium plasma, electron diffusion across the shock front resulting from high electron mobility, and the propagation of ion-acoustic waves generated at the shock front. Using a turbulence model based on reduced kinetic theory, analysis of the observed results suggest a role for turbulence in anomalous shock dynamics in weakly ionized media and plasma-induced hypersonic drag reduction.

  9. Inductance of rf-wave-heated plasmas.

    Science.gov (United States)

    Farshi, E; Todo, Y

    2003-03-14

    The inductance of rf-wave-heated plasmas is derived. This inductance represents the inductance of fast electrons located in a plateau during their acceleration due to electric field or deceleration due to collisions and electric field. This inductance has been calculated for small electric fields from the two-dimensional Fokker-Planck equation as the flux crossing the surface of critical energy mv(2)(ph)/2 in the velocity space. The new expression may be important for radio-frequency current drive ramp-up, current drive efficiency, current profile control, and so on in tokamaks. This inductance may be incorporated into transport codes that study plasma heating by rf waves.

  10. Collisional Drift Waves in Stellarator Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    J.L.V. Lewandowski

    2003-10-07

    A computational study of resistive drift waves in the edge plasma of a stellarator with an helical magnetic axis is presented. Three coupled field equations, describing the collisional drift wave dynamics in the linear approximation, are solved as an initial-value problem along the magnetic field line. The magnetohydrodynamic equilibrium is obtained from a three-dimensional local equilibrium model. The use of a local magnetohydrodynamic equilibrium model allows for a computationally efficient systematic study of the impact of the magnetic field structure on drift wave stability.

  11. On the freak waves in mesospheric plasma

    Science.gov (United States)

    El-Labany, S. K.; El-Shewy, E. K.; El-Bedwehy, N. A.; El-Razek, H. N. Abd; El-Rahman, A. A.

    2017-03-01

    The nonlinear properties of dusty ionic freak waves have been studied in homogeneous, unmagnetized dusty plasma system containing ions, isothermal electrons, negative and positive grains. By using the derivative expansion method and assuming strongly dispersive medium, the basic model equations are reduced to a nonlinear form of Schrodinger equation (NLSE). One of the solutions of the NLSE in the unstable region is the rational one which is responsible for the creation of the freak profiles. The reliance of freak waves profile on dusty grains charge and carrier wave number are discussed.

  12. Plasma shock waves excited by THz radiation

    Science.gov (United States)

    Rudin, S.; Rupper, G.; Shur, M.

    2016-10-01

    The shock plasma waves in Si MOS, InGaAs and GaN HEMTs are launched at a relatively small THz power that is nearly independent of the THz input frequency for short channel (22 nm) devices and increases with frequency for longer (100 nm to 1 mm devices). Increasing the gate-to-channel separation leads to a gradual transition of the nonlinear waves from the shock waves to solitons. The mathematics of this transition is described by the Korteweg-de Vries equation that has the single propagating soliton solution.

  13. The Potential for Ambient Plasma Wave Propulsion

    Science.gov (United States)

    Gilland, James H.; Williams, George J.

    2016-01-01

    A truly robust space exploration program will need to make use of in-situ resources as much as possible to make the endeavor affordable. Most space propulsion concepts are saddled with one fundamental burden; the propellant needed to produce momentum. The most advanced propulsion systems currently in use utilize electric and/or magnetic fields to accelerate ionized propellant. However, significant planetary exploration missions in the coming decades, such as the now canceled Jupiter Icy Moons Orbiter, are restricted by propellant mass and propulsion system lifetimes, using even the most optimistic projections of performance. These electric propulsion vehicles are inherently limited in flexibility at their final destination, due to propulsion system wear, propellant requirements, and the relatively low acceleration of the vehicle. A few concepts are able to utilize the environment around them to produce thrust: Solar or magnetic sails and, with certain restrictions, electrodynamic tethers. These concepts focus primarily on using the solar wind or ambient magnetic fields to generate thrust. Technically immature, quasi-propellantless alternatives lack either the sensitivity or the power to provide significant maneuvering. An additional resource to be considered is the ambient plasma and magnetic fields in solar and planetary magnetospheres. These environments, such as those around the Sun or Jupiter, have been shown to host a variety of plasma waves. Plasma wave propulsion takes advantage of an observed astrophysical and terrestrial phenomenon: Alfven waves. These are waves that propagate in the plasma and magnetic fields around and between planets and stars. The generation of Alfven waves in ambient magnetic and plasma fields to generate thrust is proposed as a truly propellantless propulsion system which may enable an entirely new matrix of exploration missions. Alfven waves are well known, transverse electromagnetic waves that propagate in magnetized plasmas at

  14. Solitons and Weakly Nonlinear Waves in Plasmas

    DEFF Research Database (Denmark)

    Pécseli, Hans

    1985-01-01

    Theoretical descriptions of solitons and weakly nonlinear waves propagating in plasma media are reviewed, with particular attention to the Korteweg-de Vries (KDV) equation and the Nonlinear Schrödinger equation (NLS). The modifications of these basic equations due to the effects of resonant...

  15. Ionization wave propagation on a micro cavity plasma array

    CERN Document Server

    Wollny, Alexander; Gebhardt, Markus; Brinkmann, Ralf Peter; Boettner, Henrik; Winter, Joerg; der Gathen, Volker Schulz-von; Mussenbrock, Thomas

    2011-01-01

    Microcavity plasma arrays are regular arrays of inverse pyramidal cavities created on positive doped silicon wafers. Each cavity acts as a microscopic dielectric barrier discharge. Operated at atmospheric pressure in argon and excited with high voltage at about 10 kHz frequency each cavity develops a localized microplasma. Experiments show a strong interaction of the individual cavities, leading to the propagation of wave-like emission structures along the array surface. This paper studies the ignition process of a micro cavity plasma array by means of a numerical simulation and confirms the experimental results. The propagation of an ionization wave is observed. Its propagation speed of 1 km/s matches experimental findings.

  16. Plasma Limiter Based on Surface Wave Plasma Excited by Microwave

    Institute of Scientific and Technical Information of China (English)

    YANG Geng; TAN Jichun; SHEN Benjian

    2008-01-01

    A novel plasma limiter, in which the plasma is excited by surface wave, is presented. The breakdown time of some gases filled in the limiter were calculated as a function of gas pres-sure, ionization degree and density of seed electrons under low pressure (0.01 ~1 Torr) and high pressure (10 ~1000 Torr) cases. The results show that the limiter filled with Xe with a pressure of 0.9 Torr, seed electron density of 1016 m-3, and ionization degree of 10-4, has a breakdown time of approximate 19.6 ns.

  17. Excitation of Ion Acoustic Waves in Confined Plasmas with Untrapped Electrons

    Science.gov (United States)

    Schamis, Hanna; Dow, Ansel; Carlsson, Johan; Kaganovich, Igor; Khrabrov, Alexander

    2015-11-01

    Various plasma propulsion devices exhibit strong electron emission from the walls either as a result of secondary processes or due to thermionic emission. To understand the electron kinetics in plasmas with strong emission, we have performed simulations using a reduced model with the LSP particle-in-cell code. This model aims to show the instability generated by the electron emission, in the form of ion acoustic waves near the sheath. It also aims to show the instability produced by untrapped electrons that propagate across the plasma, similarly to a beam, and can drive ion acoustic waves in the plasma bulk. This work was made possible by funding from the Department of Energy for the Summer Undergraduate Laboratory Internship (SULI) program. This work is supported by the US DOE Contract No.DE-AC02-09CH11466.

  18. Tunable Plasma-Wave Laser Amplifier

    Science.gov (United States)

    Bromage, J.; Haberberger, D.; Davies, A.; Bucht, S.; Zuegel, J. D.; Froula, D. H.; Trines, R.; Bingham, R.; Sadler, J.; Norreys, P. A.

    2016-10-01

    Raman amplification is a process by which a long energetic pump pulse transfers its energy to a counter-propagating short seed pulse through a resonant electron plasma wave. Since its conception, theory and simulations have shown exciting results with up to tens of percent of energy transfer from the pump to the seed pulse. However, experiments have yet to surpass transfer efficiencies of a few percent. A review of past literature shows that largely chirped pump pulses and finite temperature wave breaking could have been the two most detrimental effects. A Raman amplification platform is being developed at the Laboratory for Laser Energetics where a combination of a high-intensity tunable seed laser with sophisticated plasma diagnostics (dynamic Thomson scattering) will make it possible to find the optimal parameter space for high-energy transfer. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  19. Cassini Radio and Plasma Wave Observations at Saturn

    Science.gov (United States)

    Gurnett, D. A.; Kurth, W. S.; Hospodarsky, G. B.; Persoon, A. M.; Averkamp, T. F.; Ceccni, B.; Lecacheux, A.; Zarka, P.; Canu, P.; Cornilleau-Wehrlin, N.

    2005-01-01

    Results are presented from the Cassini radio and plasma wave instrument during the approach and first few orbits around Saturn. During the approach the intensity modulation of Saturn Kilometric Radiation (SKR) showed that the radio rotation period of Saturn has increased to 10 hr 45 min plus or minus 36 sec, about 6 min longer than measured by Voyager in 1980-81. Also, many intense impulsive radio signals called Saturn Electrostatic Discharges (SEDs) were detected from saturnian lightning, starting as far as 1.08 AU from Saturn, much farther than terrestrial lightning can be detected from Earth. Some of the SED episodes have been linked to cloud systems observed in Saturn s atmosphere by the Cassini imaging system. Within the magnetosphere plasma wave emissions have been used to construct an electron density profile through the inner region of the magnetosphere. With decreasing radial distance the electron density increases gradually to a peak of about 100 per cubic centimeter near the outer edge of the A ring, and then drops precipitously to values as low as .03 per cubic centimeter over the rings. Numerous nearly monochromatic whistler-mode emissions were observed as the spacecraft passed over the rings that are believed to be produced by meteoroid impacts on the rings. Whistlermode emissions, similar to terrestrial auroral hiss were also observed over the rings, indicating that an electrodynamic interaction, similar to auroral particle acceleration, may be occurring in or near the rings. During the Titan flybys Langmuir probe and plasma wave measurements provided observations of the density and temperature in Titan's ionosphere.

  20. Geotail MCA Plasma Wave Investigation Data Analysis

    Science.gov (United States)

    Anderson, Roger R.

    1997-01-01

    The primary goals of the International Solar Terrestrial Physics/Global Geospace Science (ISTP/GGS) program are identifying, studying, and understanding the source, movement, and dissipation of plasma mass, momentum, and energy between the Sun and the Earth. The GEOTAIL spacecraft was built by the Japanese Institute of Space and Astronautical Science and has provided extensive measurements of entry, storage, acceleration, and transport in the geomagnetic tail and throughout the Earth's outer magnetosphere. GEOTAIL was launched on July 24, 1992, and began its scientific mission with eighteen extensions into the deep-tail region with apogees ranging from around 60 R(sub e) to more than 208 R(sub e) in the period up to late 1994. Due to the nature of the GEOTAIL trajectory which kept the spacecraft passing into the deep tail, GEOTAIL also made 'magnetopause skimming passes' which allowed measurements in the outer magnetosphere, magnetopause, magnetosheath, bow shock, and upstream solar wind regions as well as in the lobe, magnetosheath, boundary layers, and central plasma sheet regions of the tail. In late 1994, after spending nearly 30 months primarily traversing the deep tail region, GEOTAIL began its near-Earth phase. Perigee was reduced to 10 R(sub e) and apogee first to 50 R(sub e) and finally to 30 R(sub e) in early 1995. This orbit provides many more opportunities for GEOTAIL to explore the upstream solar wind, bow shock, magnetosheath, magnetopause, and outer magnetosphere as well as the near-Earth tail regions. The WIND spacecraft was launched on November 1, 1994 and the POLAR spacecraft was launched on February 24, 1996. These successful launches have dramatically increased the opportunities for GEOTAIL and the GGS spacecraft to be used to conduct the global research for which the ISTP program was designed. The measurement and study of plasma waves have made and will continue to make important contributions to reaching the ISTP/GGS goals and solving the

  1. Collisional damping rates for plasma waves

    Science.gov (United States)

    Tigik, S. F.; Ziebell, L. F.; Yoon, P. H.

    2016-06-01

    The distinction between the plasma dynamics dominated by collisional transport versus collective processes has never been rigorously addressed until recently. A recent paper [P. H. Yoon et al., Phys. Rev. E 93, 033203 (2016)] formulates for the first time, a unified kinetic theory in which collective processes and collisional dynamics are systematically incorporated from first principles. One of the outcomes of such a formalism is the rigorous derivation of collisional damping rates for Langmuir and ion-acoustic waves, which can be contrasted to the heuristic customary approach. However, the results are given only in formal mathematical expressions. The present brief communication numerically evaluates the rigorous collisional damping rates by considering the case of plasma particles with Maxwellian velocity distribution function so as to assess the consequence of the rigorous formalism in a quantitative manner. Comparison with the heuristic ("Spitzer") formula shows that the accurate damping rates are much lower in magnitude than the conventional expression, which implies that the traditional approach over-estimates the importance of attenuation of plasma waves by collisional relaxation process. Such a finding may have a wide applicability ranging from laboratory to space and astrophysical plasmas.

  2. Waves in relativistic electron beam in low-density plasma

    Science.gov (United States)

    Sheinman, I.; Sheinman (Chernenco, J.

    2016-11-01

    Waves in electron beam in low-density plasma are analyzed. The analysis is based on complete electrodynamics consideration. Dependencies of dispersion laws from system parameters are investigated. It is shown that when relativistic electron beam is passed through low-density plasma surface waves of two types may exist. The first type is a high frequency wave on a boundary between the beam and neutralization area and the second type wave is on the boundary between neutralization area and stationary plasma.

  3. Mid infrared emission spectroscopy of carbon plasma

    Science.gov (United States)

    Nemes, Laszlo; Brown, Ei Ei; Yang, Clayton S.-C.; Hommerich, Uwe

    2017-01-01

    Mid infrared time-resolved emission spectra were recorded from laser-induced carbon plasma. These spectra constitute the first study of carbon materials LIB spectroscopy in the mid infrared range. The carbon plasma was induced using a Q-switched Nd: YAG laser. The laser beam was focused to high purity graphite pellets mounted on a translation stage. Mid infrared emission from the plasma in an atmospheric pressure background gas was detected by a cooled HgCdTe detector in the range 4.4-11.6 μm, using long-pass filters. LIB spectra were taken in argon, helium and also in air. Despite a gate delay of 10 μs was used there were strong backgrounds in the spectra. Superimposed on this background broad and noisy emission bands were observed, the form and position of which depended somewhat on the ambient gas. The spectra were digitally smoothed and background corrected. In argon, for instance, strong bands were observed around 4.8, 6.0 and 7.5 μm. Using atomic spectral data by NIST it could be concluded that carbon, argon, helium and nitrogen lines from neutral and ionized atoms are very weak in this spectral region. The width of the infrared bands supports molecular origin. The infrared emission bands were thus compared to vibrational features of carbon molecules (excluding C2) of various sizes on the basis of previous carbon cluster infrared absorption and emission spectroscopic analyses in the literature and quantum chemical calculations. Some general considerations are given about the present results.

  4. Mid infrared emission spectroscopy of carbon plasma.

    Science.gov (United States)

    Nemes, Laszlo; Brown, Ei Ei; S-C Yang, Clayton; Hommerich, Uwe

    2017-01-05

    Mid infrared time-resolved emission spectra were recorded from laser-induced carbon plasma. These spectra constitute the first study of carbon materials LIB spectroscopy in the mid infrared range. The carbon plasma was induced using a Q-switched Nd: YAG laser. The laser beam was focused to high purity graphite pellets mounted on a translation stage. Mid infrared emission from the plasma in an atmospheric pressure background gas was detected by a cooled HgCdTe detector in the range 4.4-11.6μm, using long-pass filters. LIB spectra were taken in argon, helium and also in air. Despite a gate delay of 10μs was used there were strong backgrounds in the spectra. Superimposed on this background broad and noisy emission bands were observed, the form and position of which depended somewhat on the ambient gas. The spectra were digitally smoothed and background corrected. In argon, for instance, strong bands were observed around 4.8, 6.0 and 7.5μm. Using atomic spectral data by NIST it could be concluded that carbon, argon, helium and nitrogen lines from neutral and ionized atoms are very weak in this spectral region. The width of the infrared bands supports molecular origin. The infrared emission bands were thus compared to vibrational features of carbon molecules (excluding C2) of various sizes on the basis of previous carbon cluster infrared absorption and emission spectroscopic analyses in the literature and quantum chemical calculations. Some general considerations are given about the present results.

  5. Electron Acoustic Waves in Pure Ion Plasmas

    Science.gov (United States)

    Anderegg, F.; Affolter, M.; Driscoll, C. F.; O'Neil, T. M.; Valentini, F.

    2012-10-01

    Electron Acoustic Waves (EAWs) are the low-frequency branch of near-linear Langmuir (plasma) waves: the frequency is such that the complex dielectric function (Dr, Di) has Dr= 0; and ``flattening'' of f(v) near the wave phase velocity vph gives Di=0 and eliminates Landau damping. Here, we observe standing axisymmetric EAWs in a pure ion column.footnotetextF. Anderegg, et al., Phys. Rev. Lett. 102, 095001 (2009). At low excitation amplitudes, the EAWs have vph˜1.4 v, in close agreement with near-linear theory. At moderate excitation strengths, EAW waves are observed over a range of frequencies, with 1.3 v vphvph.footnotetextF. Valentini et al., arXiv:1206.3500v1. Large amplitude EAWs have strong phase-locked harmonic content, and experiments will be compared to same-geometry simulations, and to simulations of KEENfootnotetextB. Afeyan et al., Proc. Inertial Fusion Sci. and Applications 2003, A.N.S. Monterey (2004), p. 213. waves in HEDLP geometries.

  6. Plasma production for electron acceleration by resonant plasma wave

    Science.gov (United States)

    Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Croia, M.; Curcio, A.; Di Giovenale, D.; Di Pirro, G. P.; Filippi, F.; Ghigo, A.; Lollo, V.; Pella, S.; Pompili, R.; Romeo, S.; Ferrario, M.

    2016-09-01

    Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV/m), enabling acceleration of electrons to GeV energy in few centimeter. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators (large energy spread, low repetition rate, and large emittance); radiofrequency-based accelerators, in fact, are limited in accelerating field (10-100 MV/m) requiring therefore hundred of meters of distances to reach the GeV energies, but can provide very bright electron bunches. To combine high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC_LAB (Ferrario et al., 2013 [1]). In particular here we focus on hydrogen plasma discharge, and in particular on the theoretical and numerical estimates of the ionization process which are very useful to design the discharge circuit and to evaluate the current needed to be supplied to the gas in order to have full ionization. Eventually, the current supplied to the gas simulated will be compared to that measured experimentally.

  7. Plasma production for electron acceleration by resonant plasma wave

    Energy Technology Data Exchange (ETDEWEB)

    Anania, M.P., E-mail: maria.pia.anania@lnf.infn.it [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Biagioni, A.; Chiadroni, E. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Cianchi, A. [University of Rome Tor Vergata - INFN, via della Ricerca Scientifica, 1, 00133 Roma (Italy); INFN, Via della Ricerca Scientifica, 1, 00133 Roma (Italy); Croia, M.; Curcio, A. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); University of Rome La Sapienza, Piazzale Aldo Moro, 2, 00185 Roma (Italy); Di Giovenale, D.; Di Pirro, G.P. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Filippi, F. [University of Rome La Sapienza, Piazzale Aldo Moro, 2, 00185 Roma (Italy); Ghigo, A.; Lollo, V.; Pella, S.; Pompili, R. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); Romeo, S. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy); University of Rome La Sapienza, Piazzale Aldo Moro, 2, 00185 Roma (Italy); Ferrario, M. [INFN - LNF, via Enrico Fermi, 40, 00044 Frascati (Italy)

    2016-09-01

    Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10–100 GV/m), enabling acceleration of electrons to GeV energy in few centimeter. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators (large energy spread, low repetition rate, and large emittance); radiofrequency-based accelerators, in fact, are limited in accelerating field (10–100 MV/m) requiring therefore hundred of meters of distances to reach the GeV energies, but can provide very bright electron bunches. To combine high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC-LAB (Ferrario et al., 2013 [1]). In particular here we focus on hydrogen plasma discharge, and in particular on the theoretical and numerical estimates of the ionization process which are very useful to design the discharge circuit and to evaluate the current needed to be supplied to the gas in order to have full ionization. Eventually, the current supplied to the gas simulated will be compared to that measured experimentally.

  8. Nonlinear Electromagnetic Waves and Spherical Arc-Polarized Waves in Space Plasmas

    Science.gov (United States)

    Tsurutani, B.; Ho, Christian M.; Arballo, John K.; Lakhina, Gurbax S.; Glassmeier, Karl-Heinz; Neubauer, Fritz M.

    1997-01-01

    We review observations of nonlinear plasma waves detected by interplanetary spacecraft. For this paper we will focus primarily on the phase-steepened properties of such waves. Plasma waves at comet Giacobini-Zinner measured by the International Cometary Explorer (ICE), at comets Halley and Grigg-Skjellerup measured by Giotto, and interplanetary Alfven waves measured by Ulysses, will be discussed and intercompared.

  9. Gravitational waves in a free isotropic plasma. II

    Energy Technology Data Exchange (ETDEWEB)

    Galtsov, D.V.; Grats, IU.V.; Melkumova, E.IU.

    1985-07-01

    The generation of gravitational waves in an isotropic homogeneous plasma is investigated theoretically, within the frame work of a recently developed formalism. The effectiveness of different mechanisms generating gravitational waves is considered. Attention is given to thermal gravitational radiation by a two-component plasma; the transformation of longitudinal plasma waves into gravitons due to current fluctuations; and the generation of gravitational waves due to Langmuir turbulence. It is shown that collective plasma effects play a critical role in the generation of gravitational waves.

  10. Model of the Dynamics of Plasma-Wave Channels in Magnetized Plasmas

    Science.gov (United States)

    Shirokov, E. A.; Chugunov, Yu. V.

    2016-06-01

    We analyze the dynamics of the plasma-wave channels excited in magnetized plasmas in the whistler frequency range. A linear theory of excitation of a plasma waveguide by an external source is developed using the quasistatic approximation. Self-consistent spatio-temporal distributions of the electric field of quasipotential waves and plasma density, which are solutions of the nonlinear nonstationary problem of the ionizing self-channeling of waves in plasmas are found on the basis of the linear theory.

  11. 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...

  12. Spin waves and spin instabilities in quantum plasmas

    CERN Document Server

    Andreev, P A

    2014-01-01

    We describe main ideas of method of many-particle quantum hydrodynamics allows to derive equations for description of quantum plasma evolution. We also present definitions of collective quantum variables suitable for quantum plasmas. We show that evolution of magnetic moments (spins) in quantum plasmas leads to several new branches of wave dispersion: spin-electromagnetic plasma waves and self-consistent spin waves. Propagation of neutron beams through quantum plasmas is also considered. Instabilities appearing due to interaction of magnetic moments of neutrons with plasma are described.

  13. Electron Bernstein Wave Emission and Mode Conversion Physics on NSTX

    Energy Technology Data Exchange (ETDEWEB)

    Diem, S J; Caughman, J B; Efthimion, P; Kugel, H; LeBlanc, B P; Preinhaelter, J; Sabbagh, S A; Urban, J

    2008-05-21

    NSTX is a spherical tokamak (ST) that operates with ne up to 1020 m-3 and BT less than 0.6 T, cutting off low harmonic electron cyclotron (EC) emission widely used for Te measurements on conventional aspect ratio tokamaks. The electron Bernstein wave (EBW) can propagate in ST plasmas and is emitted at EC harmonics. These properties suggest thermal EBW emission (EBE) may be used for local Te measurements in the ST. Practically, a robust Te(R,t) EBE diagnostic requires EBW transmission efficiencies of > 90% for a wide range of plasma conditions. EBW emission and coupling physics were studied on NSTX with an obliquely viewing EBW to O-mode (B-X-O) diagnostic with two remotely steered antennas, coupled to absolutely calibrated radiometers. While Te(R,t) measurements with EBW emission on NSTX were possible, they were challenged by several issues. Rapid fluctuations in edge ne scale length resulted in > 20% changes in the low harmonic B-X-O transmission efficiency. Also, B-X-O transmission efficiency 2 during H-modes was observed to decay by a factor of 5-10 to less than a few percent. The B-X-O transmission behavior during H-modes was reproduced by EBE simulations that predict that EBW collisional damping can significantly reduce emission when Te < 30 eV inside the B-X-O mode conversion (MC) layer. Initial edge lithium conditioning experiments during H-modes have shown that evaporated lithium can increase Te inside the B-X-O MC layer, significantly increasing B-X-O transmission.

  14. Electromagnetic Emission from Laser Wakefields in Magnetized Underdense Plasmas

    Institute of Scientific and Technical Information of China (English)

    胡志丹; 盛政明; 丁文君; 王伟民; 董全力; 张杰

    2012-01-01

    A wakefield driven by a short intense laser pulse in a perpendicularly magnetized underdense plasma is studied analytically and numerically for both weakly relativistic and highly relativistic situations. Owing to the DC magnetic field, a transverse component of the electric fields associated with the wakefield appears, while the longitudinal wave is not greatly affected by the magnetic field up to 22 Tesla. Moreover, the scaling law of the transverse field versus the longitudinal field is derived. One-dimensional particle-in-cell simulation results confirm the analytical results. Wakefield transmission through the plasma-vacuum boundary, where electromagnetic emission into vacuum occurs, is also investigated numerically. These results are useful for the generation of terahertz radiation and the diagnosis of laser wakefields.

  15. Radiation Heat Waves in Gold Plasma

    Institute of Scientific and Technical Information of China (English)

    YANG Jia-Min; XU Yan; DING Yao-Nan; LAI Dong-Xian; DING Yong-Kun; JIANG Shao-En; ZHENG Zhi-Jian; MIAO Wen-Yong

    2003-01-01

    Eight beams 0.35/um laser with pulse duration of about 1.0ns and energy of 260 J per beam was injected into a cylindrical cavity to generate intense x-ray radiation on the "Shengguang I" high power laser facility. Gold foils with a thickness in the range of 0.09-0.52/j,m were attached on the diagnostic hole of the cavity and ablated by the intense x-ray radiation. The propagating radiation heat wave in the high-Z gold plasma was observed clearly. For comparison, we also simulated the experimental results.

  16. Plasma-maser instability of the ion acoustics wave in the presence of lower hybrid wave turbulence in inhomogeneous plasma

    Indian Academy of Sciences (India)

    M Singh; P N Deka

    2006-03-01

    A theoretical study is made on the generation mechanism of ion acoustics wave in the presence of lower hybrid wave turbulence field in inhomogeneous plasma on the basis of plasma-maser interaction. The lower hybrid wave turbulence field is taken as the low-frequency turbulence field. The growth rate of test high frequency ion acoustics wave is obtained with the involvement of spatial density gradient parameter. A comparative study of the role of density gradient for the generation of ion acoustics wave on the basis of plasma-maser effect is presented. It is found that the density gradient influences the growth rate of ion acoustics wave.

  17. Electromagnetic-wave excitation in a large laboratory beam-plasma system

    Science.gov (United States)

    Whelan, D. A.; Stenzel, R. L.

    1981-01-01

    The mechanism by which unstable electrostatic waves of a beam-plasma system are converted into observed electromagnetic waves is of current interest in space physics and in tokamak fusion research. The process involved in the conversion of electrostatic to electromagnetic waves at the critical layer is well understood. However, the radiation from uniform plasmas cannot be explained on the basis of this process. In connection with certain difficulties, it has not yet been possible to establish the involved emission processes by means of experimental observations. In the considered investigation these difficulties are overcome by employing a large laboratory plasma in a parameter range suitable for detailed diagnostics. A finite-diameter electron beam is injected into a uniform quiescent afterglow plasma of dimensions large compared with electromagnetic wavelengths. The considered generation mechanism concerning the electromagnetic waves is conclusively confirmed by observing the temporal evolution of an instability

  18. Stable Propagating Waves and Wake Fields in Relativistic Electromagnetic Plasma

    Institute of Scientific and Technical Information of China (English)

    DUAN Yi-Shi; XIE Bai-Song; TIAN Miao; YIN Xin-Tao; ZHANG Xin-Hui

    2008-01-01

    Stable propagating waves and wake fields in relativistic electromagnetic plasma are investigated. The incident electromagnetic field has a finite initial constant amplitude meanwhile the longitudinal momentum of electrons is taken into account in the problem. It is found that in the moving frame with transverse wave group velocity the stable propagating transverse electromagnetic waves and longitudinal plasma wake fields can exist in the appropriate regime of plasma.

  19. Magnetohydrodynamic waves in fusion and astrophysical plasmas.

    Science.gov (United States)

    Goedbloed, J. P.

    Macroscopic plasma dynamics in both controlled thermonuclear confinement machines and in the atmospheres of X-ray emitting stars is described by the equations of magnetohydrodynamics. This provides a vast area of overlapping research activities which is presently actively pursued. In this lecture the author concentrates on some important differences in the dynamics of the two confined plasma systems related to the very different geometries that are encountered and, thus, the role of the different boundary conditions that have to be posed. As a result, the basic MHD waves in a tokamak are quite different from those found in a solar magnetic flux tube. The result is that, whereas the three well-known MHD waves can be traced stepwise in the curved geometry of a tokamak, their separate existence is eliminated right from the start in a line-tied coronal loop because line-tying in general conflicts with the phase relationships between the vector components of the three velocity fields. The consequences are far-reaching, viz. completely different resonant frequencies and continuous spectra, absence of rational magnetic surfaces, and irrelevance of local marginal stability theory for coronal magnetic loops.

  20. Breaking of Large Amplitude Electron Plasma Wave in a Maxwellian Plasma

    CERN Document Server

    Mukherjee, Arghya

    2016-01-01

    The determination of maximum possible amplitude of a coherent longitudinal plasma oscillation/wave is a topic of fundamental importance in non-linear plasma physics. The amplitudes of these large amplitude plasma waves is limited by a phenomena called wave breaking which may be induced by several non-linear processes. It was shown by Coffey [T. P. Coffey, Phys. Fluids 14, 1402 (1971)] using a "water-bag" distribution for electrons that, in a warm plasma the maximum electric field amplitude and density amplitude implicitly depend on the electron temperature, known as Coffey's limit. In this paper, the breaking of large amplitude freely running electron plasma wave in a homogeneous warm plasma where electron's velocity distribution is Maxwellian has been studied numerically using 1D Particle in Cell (PIC) simulation method. It is found that Coffey's propagating wave solutions, which was derived using a "water-bag" distribution for electrons, also represent propagating waves in a Maxwellian plasma. Coffey's wave...

  1. Second harmonic electromagnetic emission of a turbulent magnetized plasma driven by a powerful electron beam

    CERN Document Server

    Timofeev, I V

    2012-01-01

    The power of second harmonic electromagnetic emission is calculated for the case when strong plasma turbulence is excited by a powerful electron beam in a magnetized plasma. It is shown that the simple analytical model of strong plasma turbulence with the assumption of a constant pump power is able to explain experimentally observed bursts of electromagnetic radiation as a consequence of separate collapse events. It is also found that the electromagnetic emission power calculated for three-wave interaction processes occurring in the long-wavelength part of turbulent spectrum is in order-of-magnitude agreement with experimental results.

  2. Relativistic electromagnetic waves in an electron-ion plasma

    Science.gov (United States)

    Chian, Abraham C.-L.; Kennel, Charles F.

    1987-01-01

    High power laser beams can drive plasma particles to relativistic energies. An accurate description of strong waves requires the inclusion of ion dynamics in the analysis. The equations governing the propagation of relativistic electromagnetic waves in a cold electron-ion plasma can be reduced to two equations expressing conservation of energy-momentum of the system. The two conservation constants are functions of the plasma stream velocity, the wave velocity, the wave amplitude, and the electron-ion mass ratio. The dynamic parameter, expressing electron-ion momentum conversation in the laboratory frame, can be regarded as an adjustable quantity, a suitable choice of which will yield self-consistent solutions when other plasma parameters were specified. Circularly polarized electromagnetic waves and electrostatic plasma waves are used as illustrations.

  3. Magnetoacoustic waves in a partially ionized two-fluid plasma

    CERN Document Server

    Soler, Roberto; Ballester, Jose Luis

    2013-01-01

    Compressible disturbances propagate in a plasma in the form of magnetoacoustic waves driven by both gas pressure and magnetic forces. In partially ionized plasmas the dynamics of ionized and neutral species are coupled due to ion-neutral collisions. As a consequence, magnetoacoustic waves propagating through a partially ionized medium are affected by the ion-neutral coupling. The degree to which the behavior of the classic waves is modified depends on the physical properties of the various species and on the relative value of the wave frequency compared to the ion-neutral collision frequency. Here, we perform a comprehensive theoretical investigation of magnetoacoustic wave propagation in a partially ionized plasma using the two-fluid formalism. We consider an extensive range of values for the collision frequency, ionization ratio, and plasma $\\beta$, so that the results are applicable to a wide variety of astrophysical plasmas. We determine the modification of the wave frequencies and study the frictional da...

  4. Registration of ELF waves in rocket-satellite experiment with plasma injection

    Science.gov (United States)

    Korobeinikov, V. G.; Oraevskii, V. N.; Ruzhin, Iu. Ia.; Sobolev, Ia. P.; Skomarovskii, V. S.; Chmyrev, V. M.; Namazov, C. A.; Pokhunkov, A. A.; Nesmeianov, V. I.

    1992-12-01

    Two rocket KOMBI-SAMA experiments with plasma injection at height 100-240 km were performed in August 1987 in the region of Brazilian magnetic anomaly (L = 1.25). The launching time of the rocket was determined so that plasma injection was at the time when COSMOS 1809 satellite passed as close as possible to magnetic tube of injection. Caesium plasma jet was produced during not less than 300 s by an electric plasma generator separated from the payload. When the satellite passed the geomagnetic tube intersecting the injection region an enhancement of ELF emission at 140 Hz, 450 Hz by a factor of 2 was registered on board the satellite. An enhancement of energetic particle flux by a factor of 4-5 was registered on board the rocket. Observed ELF emission below 100 Hz is interpreted as the generation of oblique electromagnetic ion-cyclotron waves due to drift plasma instability at the front of the plasma jet.

  5. Space and Astrophysical Plasmas : Ionospheric plasma by VHF waves

    Indian Academy of Sciences (India)

    R P Patel; Abhay Kumar Singh; R P Singh

    2000-11-01

    The amplitude scintillations of very high frequency electromagnetic wave transmitted from geo-stationary satellite at 244.168 MHz have been recorded at Varanasi (geom. lat. 14° 55'N) during 1991 to 1999. The data are analyzed to determine the statistical features of overhead ionospheric plasma irregularities which are mostly of small duration < 30 minutes and are predominant during pre-midnight period. The increase of solar activity generally increases the depth of scintillation. The auto-correlation functions and power spectra of scintillations predict that the scale length of these irregularities varies from 200–500 m having velocity of movement between 75 m/sec to 200 m/sec. These results agree well with the results obtained by other workers.

  6. Plasmonic emission and plasma lattice structures induced by pulsed laser in Purcell cavity on silicon

    Institute of Scientific and Technical Information of China (English)

    黄伟其; 黄忠梅; 苗信建; 刘世荣; 秦朝建

    2015-01-01

    The lattice structure image of a plasma standing wave in a Purcell cavity of silicon is observed. The plasma wave produced by the pulsed laser could be used to fabricate the micro-nanostructure of silicon. The plasma lattice structures induced by the nanosecond pulsed laser in the cavity may be similar to the Wigner crystal structure. It is interesting that the beautiful diffraction pattern could be observed in the plasma lattice structure. The radiation lifetime could be shortened to the nanosecond range throughout the entire spectral range and the relaxation time could be lengthened for higher emission efficiency in the Purcell cavity, which results in the fact that the plasmonic emission is stronger and its threshold is lower.

  7. Effects of Schwarzschild Geometry on Isothermal Plasma Wave Dispersion

    CERN Document Server

    Sharif, M

    2007-01-01

    The behavior of isothermal plasma waves has been analyzed near the Schwarzschild horizon. We consider a non-rotating background with non-magnetized and magnetized plasmas. The general relativistic magnetohydrodynamical equations for the Schwarzschild planar analogue spacetime with an isothermal state of the plasma are formulated. The perturbed form of these equations is linearized and Fourier analyzed by introducing simple harmonic waves. The determinant of these equations in each case leads to a complex dispersion relation, which gives complex values of the wave number. This has been used to discuss the nature of the waves and their characteristics near the horizon.

  8. Wave rectification in plasma sheaths surrounding electric field antennas

    Science.gov (United States)

    Boehm, M. H.; Carlson, C. W.; Mcfadden, J. P.; Clemmons, J. H.; Ergun, R. E.; Mozer, F. S.

    1994-01-01

    Combined measurements of Langmuir or broadband whistler wave intensity and lower-frequency electric field waveforms, all at 10-microsecond time resolution, were made on several recent sounding rockets in the auroral ionosphere. It is found that Langmuir and whistler waves are partically rectified in the plasma sheaths surrounding the payload and the spheres used as antennas. This sheath rectification occurs whenever the high frequency (HF) potential across the sheath becomes of the same order as the electron temperature or higher, for wave frequencies near or above the ion plasma frequency. This rectification can introduce false low-frequency waves into measurements of electric field spectra when strong high-frequency waves are present. Second harmonic signals are also generated, although at much lower levels. The effect occurs in many different plasma conditions, primarily producing false waves at frequencies that are low enough for the antenna coupling to the plasma to be resistive.

  9. Simulation of laser-driven plasma beat-wave propagation in collisional weakly relativistic plasmas

    Science.gov (United States)

    Kaur, Maninder; Nandan Gupta, Devki

    2016-11-01

    The process of interaction of lasers beating in a plasma has been explored by virtue of particle-in-cell (PIC) simulations in the presence of electron-ion collisions. A plasma beat wave is resonantly excited by ponderomotive force by two relatively long laser pulses of different frequencies. The amplitude of the plasma wave become maximum, when the difference in the frequencies is equal to the plasma frequency. We propose to demonstrate the energy transfer between the laser beat wave and the plasma wave in the presence of electron-ion collision in nearly relativistic regime with 2D-PIC simulations. The relativistic effect and electron-ion collision both affect the energy transfer between the interacting waves. The finding of simulation results shows that there is a considerable decay in the plasma wave and the field energy over time in the presence of electron-ion collisions.

  10. Effects of Schwarzschild Geometry on Isothermal Plasma Wave Dispersion

    OpenAIRE

    Sharif, M.; Sheikh, Umber

    2007-01-01

    The behavior of isothermal plasma waves has been analyzed near the Schwarzschild horizon. We consider a non-rotating background with non-magnetized and magnetized plasmas. The general relativistic magnetohydrodynamical equations for the Schwarzschild planar analogue spacetime with an isothermal state of the plasma are formulated. The perturbed form of these equations is linearized and Fourier analyzed by introducing simple harmonic waves. The determinant of these equations in each case leads ...

  11. Cyclotron waves in a non-neutral plasma column

    Energy Technology Data Exchange (ETDEWEB)

    Dubin, Daniel H. E. [Department of Physics, University of California at San Diego, La Jolla, California 92093 (United States)

    2013-04-15

    A kinetic theory of linear electrostatic plasma waves with frequencies near the cyclotron frequency {Omega}{sub c{sub s}} of a given plasma species s is developed for a multispecies non-neutral plasma column with general radial density and electric field profiles. Terms in the perturbed distribution function up to O(1/{Omega}{sub c{sub s}{sup 2}}) are kept, as are the effects of finite cyclotron radius r{sub c} up to O(r{sub c}{sup 2}). At this order, the equilibrium distribution is not Maxwellian if the plasma temperature or rotation frequency is not uniform. For r{sub c}{yields}0, the theory reproduces cold-fluid theory and predicts surface cyclotron waves propagating azimuthally. For finite r{sub c}, the wave equation predicts that the surface wave couples to radially and azimuthally propagating Bernstein waves, at locations where the wave frequency equals the local upper hybrid frequency. The equation also predicts a second set of Bernstein waves that do not couple to the surface wave, and therefore have no effect on the external potential. The wave equation is solved both numerically and analytically in the WKB approximation, and analytic dispersion relations for the waves are obtained. The theory predicts that both types of Bernstein wave are damped at resonances, which are locations where the Doppler-shifted wave frequency matches the local cyclotron frequency as seen in the rotating frame.

  12. The energy density of a Landau damped plasma wave

    NARCIS (Netherlands)

    Best, R. W. B.

    1999-01-01

    In this paper some theories about the energy of a Landau damped plasma wave are discussed and new initial conditions are proposed. Analysis of a wave packet, rather than an infinite wave, gives a clear picture of the energy transport from field to particles. Initial conditions are found which excite

  13. Does the Decay Wave Propagate Forwards in Dusty Plasmas?

    Institute of Scientific and Technical Information of China (English)

    谢柏松

    2002-01-01

    The decay interaction of the ion acoustic wave in a dusty plasma with variable-charge dust grains is studied.Even if strong charging relaxation for dust grains and the short wavelength regime for ion waves are included, it is found that the decay wave must be backward propagating.

  14. Evidence for Langmuir wave collapse in the interplanetary plasma

    Science.gov (United States)

    Kellogg, Paul J.; Goetz, K.; Howard, R. L.; Monson, S. J.

    1992-01-01

    With the Fast Envelope Sampler part of the URAP experiment on Ulysses, there is observed much rapidly varying structure in plasma waves in the solar wind. Extremely narrow (1 ms) structures observed together with electrostatic Langmuir waves, as well as some broader Langmuir wave packets are discussed.

  15. Linear theory of plasma filled backward wave oscillator

    Indian Academy of Sciences (India)

    Preeti Vyas; Arti Gokhale; Y Choyal; K P Maheshwari

    2001-05-01

    An analytical and numerical study of backward wave oscillator (BWO) in linear regime is presented to get an insight into the excitation of electromagnetic waves as a result of the interaction of the relativistic electron beam with a slow wave structure. The effect of background plasma on the BWO instability is also presented.

  16. Surface-wave capillary plasmas in helium: modeling and experiment

    Science.gov (United States)

    Santos, M.; Alves, L. L.; Noel, C.; Belmonte, T.

    2012-10-01

    In this paper we use both simulations and experiments to study helium discharges (99.999% purity) sustained by surface-waves (2.45 GHz frequency), in capillary tubes (3 mm radius) at atmospheric pressure. Simulations use a self-consistent homogeneous and stationary collisional-radiative model that solves the rate balance equations for the different species present in the plasma (electrons, the He^+ and He2^+ ions, the He(nexcimers) and the gas thermal balance equation, coupled to the two-term electron Boltzmann equation (including direct and stepwise collisions as well as electron-electron collisions). Experiments use optical emission spectroscopy diagnostics to measure the electron density (Hβ Stark broadening), the gas temperature (ro-vibrational transitions of OH, present at trace concentrations), and the populations of different excited states. Model predictions at 1.7x10^13 cm-3 electron density (within the range estimated experimentally) are in good agreement with measurements (deviations < 10%) of (i) the excitation spectrum and the excitation temperatures (2795 ± 115 K, obtained from the Boltzmann-plot of the excited state populations, with energies lying between 22.7 and 24.2 eV), (ii) the power coupled to the plasma (˜ 180 ± 10 W), and (iii) the gas temperature (˜ 1700 ± 100 K). We discuss the extreme dependence of model results (particularly the gas temperature) on the power coupled to the plasma.

  17. Surface wave and linear operating mode of a plasma antenna

    Energy Technology Data Exchange (ETDEWEB)

    Bogachev, N. N., E-mail: bgniknik@yandex.ru; Bogdankevich, I. L.; Gusein-zade, N. G.; Rukhadze, A. A. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2015-10-15

    The relation between the propagation conditions of a surface electromagnetic wave along a finiteradius plasma cylinder and the linear operating mode of a plasma antenna is investigated. The solution to the dispersion relation for a surface wave propagating along a finite-radius plasma cylinder is analyzed for weakly and strongly collisional plasmas. Computer simulations of an asymmetrical plasma dipole antenna are performed using the KARAT code, wherein the dielectric properties of plasma are described in terms of the Drude model. The plasma parameters corresponding to the linear operating mode of a plasma antenna are determined. It is demonstrated that the characteristics of the plasma antenna in this mode are close to those of an analogous metal antenna.

  18. ALFVEN WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA

    Energy Technology Data Exchange (ETDEWEB)

    Soler, R.; Ballester, J. L.; Terradas, J. [Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Carbonell, M., E-mail: roberto.soler@uib.es, E-mail: joseluis.ballester@uib.es, E-mail: jaume.terradas@uib.es, E-mail: marc.carbonell@uib.es [Departament de Matematiques i Informatica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)

    2013-04-20

    Alfven waves are a particular class of magnetohydrodynamic waves relevant in many astrophysical and laboratory plasmas. In partially ionized plasmas the dynamics of Alfven waves is affected by the interaction between ionized and neutral species. Here we study Alfven waves in a partially ionized plasma from the theoretical point of view using the two-fluid description. We consider that the plasma is composed of an ion-electron fluid and a neutral fluid, which interact by means of particle collisions. To keep our investigation as general as possible, we take the neutral-ion collision frequency and the ionization degree as free parameters. First, we perform a normal mode analysis. We find the modification due to neutral-ion collisions of the wave frequencies and study the temporal and spatial attenuation of the waves. In addition, we discuss the presence of cutoff values of the wavelength that constrain the existence of oscillatory standing waves in weakly ionized plasmas. Later, we go beyond the normal mode approach and solve the initial-value problem in order to study the time-dependent evolution of the wave perturbations in the two fluids. An application to Alfven waves in the low solar atmospheric plasma is performed and the implication of partial ionization for the energy flux is discussed.

  19. An Overview of Observations by the Cassini Radio and Plasma Wave Investigation at Earth

    Science.gov (United States)

    Kurth, W. S.; Hospodarsky, G. B.; Gurnett, D. A.; Kaiser, M. L.; Wahlund, J.-E.; Roux, A.; Canu, P.; Zarka, P.; Tokarev, Y.

    2001-01-01

    On August 18, 1999, the Cassini spacecraft flew by Earth at an altitude of 1186 km on its way to Saturn. Although the flyby was performed exclusively to provide the spacecraft with sufficient velocity to get to Saturn, the radio and plasma wave science (RPWS) instrument, along with several others, was operated to gain valuable calibration data and to validate the operation of a number of capabilities. In addition, an opportunity to study the terrestrial radio and plasma wave environment with a highly capable instrument on a swift fly-through of the magnetosphere was afforded by the encounter. This paper provides an overview of the RPWS observations, at Earth, including the identification of a number of magnetospheric plasma wave modes, an accurate measurement of the plasma density over a significant portion of the trajectory using the natural wave spectrum in addition to a relaxation sounder and Langmuir probe, the detection of natural and human-produced radio emissions, and the validation of the capability to measure the wave normal angle and Poynting flux of whistler-mode chorus emissions. The results include the observation of a double-banded structure at closest' approach including a band of Cerenkov emission bounded by electron plasma and upper hybrid frequencies and an electron cyclotron harmonic band just above the second harmonic of the electron cyclotron frequency. In the near-Earth plasma sheet, evidence for electron phase space holes is observed, similar to those first reported by Geotail in the magnetotail. The wave normal analysis confirms the Polar result that chorus is generated very close to the magnetic equator and propagates to higher latitudes. The integrated power flux of auroral kilometric radiation is also used to identify a series of substorms observed during the outbound passage through the magnetotail.

  20. Testing THEMIS wave measurements against the cold plasma theory

    Science.gov (United States)

    Taubenschuss, Ulrich; Santolik, Ondrej; Le Contel, Olivier; Bonnell, John

    2016-04-01

    The THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission records a multitude of electromagnetic waves inside Earth's magnetosphere and provides data in the form of high-resolution electric and magnetic waveforms. We use multi-component measurements of whistler mode waves and test them against the theory of wave propagation in a cold plasma. The measured ratio cB/E (c is speed of light in vacuum, B is magnetic wave amplitude, E is electric wave amplitude) is compared to the same quantity calculated from cold plasma theory over linearized Faraday's law. The aim of this study is to get estimates for measurement uncertainties, especially with regard to the electric field and the cold plasma density, as well as evaluating the validity of cold plasma theory inside Earth's radiation belts.

  1. Generation of powerful terahertz emission in a beam-driven strong plasma turbulence

    CERN Document Server

    Arzhannikov, A V

    2012-01-01

    Generation of terahertz electromagnetic radiation due to coalescence of upper-hybrid waves in the long-wavelength region of strong plasma turbulence driven by a high-current relativistic electron beam in a magnetized plasma is investigated. The width of frequency spectrum as well as angular characteristics of this radiation for various values of plasma density and turbulence energy are calculated using the simple theoretical model adequately describing beam-plasma experiments at mirror traps. It is shown that the power density of electromagnetic emission at the second harmonic of plasma frequency in the terahertz range for these laboratory experiments can reach the level of 1 ${MW/cm}^3$ with 1% conversion efficiency of beam energy losses to electromagnetic emission.

  2. Excitation of Electromagnetic Waves by an Electron Ring Beam in a Magnetized Plasma Waveguide

    Institute of Scientific and Technical Information of China (English)

    周国成; 吴京生; 王德驹; 陈雁萍

    2002-01-01

    We study the resonant interactions between an electron ring beam and plasma waveguide modes. This is motivatedby the research of radio emission in low solar corona. We consider a density-depleted duct (above an active regionnear a flare site) that may be treated as a magnetized plasma waveguide. The electromagnetic waves excited inthe waveguide are classified into the so-called E-type and B-type waves. The results show that there are twounstable modes of B-type waves propagating parallel and anti-parallel to the direction of the electron beam. Theeffect of the finite radius and boundary conditions of the waveguide on the excitation of waveguide modes isimportant. For a given B-type mode, the smaller the radius R, the larger the temporal and spatial amplificationrate. We suggest that these excited waveguide modes could be one of the processes responsible for the observedsolar radio emission.

  3. Ion cyclotron emission in tokamak plasmas; Emission cyclotronique ionique dans les plasmas de tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Fraboulet, D.

    1996-09-17

    Detection of {alpha}(3.5 MeV) fusion products will be of major importance for the achievement of self sustained discharges in fusion thermonuclear reactors. Due to their cyclotronic gyration in the confining magnetic field of a tokamak, {alpha} particles are suspected to radiate in the radio-frequency band [RF: 10-500 MHz]. Our aim is to determine whether detection of RF emission radiated from a reactor plasma can provide information concerning those fusion products. We observed experimentally that the RF emission radiated from fast ions situated in the core of the discharge is detectable with a probe located at the plasma edge. For that purpose, fast temporal acquisition of spectral power was achieved in a narrow frequency band. We also propose two complementary models for this emission. In the first one, we describe locally the energy transfer between the photon population and the plasma and we compute the radiation equilibrium taking place in the tokamak. {alpha} particles are not the unique species involved in the equilibrium and it is necessary to take into account all other species present in the plasma (Deuterium, Tritium, electrons,...). Our second model consists in the numerical resolution of the Maxwell-Vlasov with the use of a variational formulation, in which all polarizations are considered and the 4 first cyclotronic harmonics are included in a 1-D slab geometry. The development of this second model leads to the proposal for an experimental set up aiming to the feasibility demonstration of a routine diagnostic providing the central {alpha} density in a reactor. (author). 166 refs.

  4. Excitation of surface plasma waves over corrugated slow-wave structure

    Indian Academy of Sciences (India)

    Ashim P Jain; Jetendra Parashar

    2005-08-01

    A microwave propagating along vacuum–dielectric–plasma interface excites surface plasma wave (SPW). A periodic slow-wave structure placed over dielectric slows down the SPW. The phase velocity of slow SPW is sensitive to height, periodicity, number of periods, thickness and the separation between dielectric and slow-wave structure. These slow SPW can couple the microwave energy to the plasma and can sustain the discharge. The efficiency of the power coupling is few per cent and is sensitive to separation between dielectric and slow-wave structure.

  5. Freak waves in negative-ion plasmas: an experiment revisited

    Science.gov (United States)

    Kourakis, Ioannis; Elkamash, Ibrahem; Reville, Brian

    2016-10-01

    Extreme events in the form of rogue waves (freak waves) occur widely in the open sea. These are space- and time-localised excitations, which appear unexpectedly and are characterised by a significant amplitude. Beyond ocean dynamics, the mechanisms underlying rogue wave formation are now being investigated in various physical contexts, including materials science, nonlinear optics and plasma physics, to mention but a few. We have undertaken an investigation, from first principles, of the occurrence of rogue waves associated with the propagation of electrostatic wavepackets in plasmas. Motivated by recent experimental considerations involving freak waves in negative-ion plasmas (NIP), we have addresed the occurrence of freak waves in NIP from first principles. An extended range of plasma parameter values was identified, where freak wave formation is possible, in terms of relevant plasma parameters. Our results extend -and partly contradict- the underlying assumptions in the interpretation of the aforementioned experiment, where a critical plasma configuration was considered and a Gardner equation approach was adopted. This work was supported from CPP/QUB funding. One of us (I. Elkamash) acknowledges financial support by an Egyptian Government fellowship.

  6. Beat-type Langmuir wave emissions associated with a type III solar radio burst: Evidence of parametric decay

    Science.gov (United States)

    Hospodarsky, G. B.; Gurnett, D. A.

    1995-01-01

    Recent measurements from the plasma wave instrument on the Galileo spacecraft have shown that Langmuir waves observed in conjunction with a type III solar radio burst contain many beat-type waveforms, with beat frequencies ranging from about 150 to 650 Hz. Strong evidence exists that the beat pattern is produced by two closely spaced narrowband components. The most likely candidates for these two waves are a beam-generated Langmuir wave and an oppositely propagating Langmuir wave produced by parametric decay. In the parametric decay process, nonlinear interactions cause the beam-driven Langmuir wave to decay into a Langmuir wave and a low-frequency ion sound wave. Comparisons of the observed beat frequency are in good agreement with theoretical predictions for a three-wave parametric decay process. Weak low-frequency emissions are also sometimes observed at the predicted frequency of the ion sound wave.

  7. A laboratory search for plasma erosion by Alfven waves

    Science.gov (United States)

    Vincena, S.; Gekelman, W.; Pribyl, P.

    2007-12-01

    Obliquely propagating shear Alfven waves with transverse wavelengths on the order of the electron inertial length or even the ion gyro-radius are commonly observed in the earth's low-altitude auroral zones. These regions are also replete with observations of electron beams and transversely heated ions. A kinetic treatment of shear Alfven wave-particle interaction reveals how these waves can be responsible for some of the observed particle acceleration. The auroral plasma environment is further enriched by the presence of field-aligned depletions in plasma density, and it has been suggested* that the Alfven waves may, in fact, be the cause of the erosion of ionospheric density. In this laboratory experiment, shear waves will be launched using a variety of proven antennas, and also allowed to grow spontaneously as Drift-Alfven modes in seeded density depletions**. Detailed measurements of the wave magnetic fields in the perpendicular density gradient regions will be presented which demonstrate the generation of short perpendicular wave scales due to the perpendicular gradient in parallel wave phase speed. Miniature in-situ particle diagnostics will also be used to look for electron and ion acceleration. The waves will also be launched into an increasing region of background magnetic field in an attempt to model the ratios of Alfven speed to electron thermal speed, and density gradient scale length to electron inertial length appropriate to the earth's auroral zone. Preliminary results will be presented on the efficacy of shear Alfven waves to self-generate plasma density depletions, or deepen ambient density inhomogeneities. The experiments are conducted at UCLA's Basic Plasma Science Facility in the Large Plasma Device. *Chaston, et al., "Ionospheric erosion by Alfven Waves," JGR, V 111, A03206, 2006. **Penano, et al., "Drift-Alfven fluctuations associated with a narrow pressure striation," Phys. Plasmas, V 7, Issue 1, pp. 144-157 (2000).

  8. Linear and Nonlinear MHD Wave Processes in Plasmas. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Tataronis, J. A.

    2004-06-01

    This program treats theoretically low frequency linear and nonlinear wave processes in magnetized plasmas. A primary objective has been to evaluate the effectiveness of MHD waves to heat plasma and drive current in toroidal configurations. The research covers the following topics: (1) the existence and properties of the MHD continua in plasma equilibria without spatial symmetry; (2) low frequency nonresonant current drive and nonlinear Alfven wave effects; and (3) nonlinear electron acceleration by rf and random plasma waves. Results have contributed to the fundamental knowledge base of MHD activity in symmetric and asymmetric toroidal plasmas. Among the accomplishments of this research effort, the following are highlighted: Identification of the MHD continuum mode singularities in toroidal geometry. Derivation of a third order ordinary differential equation that governs nonlinear current drive in the singular layers of the Alfvkn continuum modes in axisymmetric toroidal geometry. Bounded solutions of this ODE implies a net average current parallel to the toroidal equilibrium magnetic field. Discovery of a new unstable continuum of the linearized MHD equation in axially periodic circular plasma cylinders with shear and incompressibility. This continuum, which we named “accumulation continuum” and which is related to ballooning modes, arises as discrete unstable eigenfrequency accumulate on the imaginary frequency axis in the limit of large mode numbers. Development of techniques to control nonlinear electron acceleration through the action of multiple coherent and random plasmas waves. Two important elements of this program aye student participation and student training in plasma theory.

  9. Effect of wave localization on plasma instabilities. Ph. D. Thesis

    Energy Technology Data Exchange (ETDEWEB)

    Levedahl, W.K.

    1987-10-01

    The Anderson model of wave localization in random media is involved to study the effect of solar wind density turbulence on plasma processes associated with the solar type III radio burst. ISEE-3 satellite data indicate that a possible model for the type III process is the parametric decay of Langmuir waves excited by solar flare electron streams into daughter electromagnetic and ion acoustic waves. The threshold for this instability, however, is much higher than observed Langmuir wave levels because of rapid wave convection of the transverse electromagnetic daughter wave in the case where the solar wind is assumed homogeneous. Langmuir and transverse waves near critical density satisfy the Ioffe-Reigel criteria for wave localization in the solar wind with observed density fluctuations -1 percent. Numerical simulations of wave propagation in random media confirm the localization length predictions of Escande and Souillard for stationary density fluctations. For mobile density fluctuations localized wave packets spread at the propagation velocity of the density fluctuations rather than the group velocity of the waves. Computer simulations using a linearized hybrid code show that an electron beam will excite localized Langmuir waves in a plasma with density turbulence. An action principle approach is used to develop a theory of non-linear wave processes when waves are localized. A theory of resonant particles diffusion by localized waves is developed to explain the saturation of the beam-plasma instability. It is argued that localization of electromagnetic waves will allow the instability threshold to be exceeded for the parametric decay discussed above.

  10. 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

  11. VUV Emission of Microwave Driven Argon Plasma Source

    Science.gov (United States)

    Henriques, Julio; Espinho, Susana; Felizardo, Edgar; Tatarova, Elena; Dias, Francisco; Ferreira, Carlos

    2013-09-01

    An experimental and kinetic modeling investigation of a low-pressure (0.1-1.2 mbar), surface wave (2.45 GHz) induced Ar plasma as a source vacuum ultraviolet (VUV) light is presented, using visible and VUV optical spectroscopy. The electron density and the relative VUV emission intensities of excited Ar atoms (at 104.8 nm and 106.6 nm) and ions (at 92.0 nm and 93.2 nm) were determined as a function of the microwave power and pressure. The experimental results were analyzed using a 2D self-consistent theoretical model based on a set of coupled equations including the electron Boltzmann equation, the rate balance equations for the most important electronic excited species and for charged particles, the gas thermal balance equation, and the wave electrodynamics. The principal collisional and radiative processes for neutral Ar(3p54s) and Ar(3p54p) and ionized Ar(3s3p6 2S1/2) levels are accounted for. Model predictions are in good agreement with the experimental measurements. This study was funded by the Foundation for Science and Technology, Portuguese Ministry of Education and Science, under the research contract PTDC/FIS/108411/2008.

  12. Acceleration of injected electrons by the plasma beat wave accelerator

    Science.gov (United States)

    Joshi, C.; Clayton, C. E.; Marsh, K. A.; Dyson, A.; Everett, M.; Lal, A.; Leemans, W. P.; Williams, R.; Katsouleas, T.; Mori, W. B.

    1992-07-01

    In this paper we describe the recent work at UCLA on the acceleration of externally injected electrons by a relativistic plasma wave. A two frequency laser was used to excite a plasma wave over a narrow range of static gas pressures close to resonance. Electrons with energies up to our detection limit of 9.1 MeV were observed when 2.1 MeV electrons were injected in the plasma wave. No accelerated electrons above the detection threshold were observed when the laser was operated on a single frequency or when no electrons were injected. Experimental results are compared with theoretical predictions, and future prospects for the plasma beat wave accelerator are discussed.

  13. Relativistic effects on the modulational instability of electron plasma waves in quantum plasma

    Indian Academy of Sciences (India)

    Basudev Ghosh; Swarniv Chandra; Sailendra Nath Paul

    2012-05-01

    Relativistic effects on the linear and nonlinear properties of electron plasma waves are investigated using the one-dimensional quantum hydrodynamic (QHD) model for a twocomponent electron–ion dense quantum plasma. Using standard perturbation technique, a nonlinear Schrödinger equation (NLSE) containing both relativistic and quantum effects has been derived. This equation has been used to discuss the modulational instability of the wave. Through numerical calculations it is shown that relativistic effects significantly change the linear dispersion character of the wave. Unlike quantum effects, relativistic effects are shown to reduce the instability growth rate of electron plasma waves.

  14. Theoretical and experimental study of cyclotronic waves in a fusion plasma; Etude theorique et experimentale des ondes cyclotroniques electroniques dans un plasma de fusion

    Energy Technology Data Exchange (ETDEWEB)

    Vezard, D.

    1994-12-20

    This thesis presents a study concerning cyclotronic waves in a plasma. It starts with an illustration of the elementary interaction between electromagnetic waves and matter.It shows that electrons from tokamak absorbs waves at cyclotronic frequency. Cyclotronic waves are studied by solving the dispersion relation in plasma; it concerns polarisation, absorption, dispersion, extinction. Then, classical theories are reminded in order to speak about decoupled electrons and their interactions. Absorption and emission properties of cyclotronic waves by electrons from a queue are described. After that, cyclotronic waves propagation is studied taking into account resonance. The last part of this thesis is dedicated to the electronic distribution function that is made by a wave spectra at a inferior hybrid frequency. (TEC). 129 refs., 75 figs.

  15. Efficient regime of electromagnetic emission in a plasma with counterstreaming electron beams

    Science.gov (United States)

    Timofeev, I. V.; Annenkov, V. V.

    2014-08-01

    Efficiency of electromagnetic emission produced in a magnetized plasma with counterstreaming electron beams was investigated using both the linear kinetic theory and particle-in-cell simulations. We calculated the growth rate of the beam-plasma instability taking into account both kinetic and relativistic effects and showed that there exists a regime in which transversely propagating electromagnetic waves can be generated by the coupling of the most unstable oblique beam-driven modes. It was confirmed by numerical simulations that such a tune-up of system parameters for a specific nonlinear process can lead to a substantial increase in electromagnetic emission efficiency. It was found that electromagnetic radiation emerging from the plasma in such a regime is generated near the harmonics of the pump frequency that is determined by the typical eigenfrequency of the beam-driven modes. It was also shown that the peak emission power can reach 5% of the maximal power lost by beam electrons.

  16. Efficient regime of electromagnetic emission in a plasma with counterstreaming electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Timofeev, I. V.; Annenkov, V. V. [Budker Institute of Nuclear Physics SB RAS and Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2014-08-15

    Efficiency of electromagnetic emission produced in a magnetized plasma with counterstreaming electron beams was investigated using both the linear kinetic theory and particle-in-cell simulations. We calculated the growth rate of the beam-plasma instability taking into account both kinetic and relativistic effects and showed that there exists a regime in which transversely propagating electromagnetic waves can be generated by the coupling of the most unstable oblique beam-driven modes. It was confirmed by numerical simulations that such a tune-up of system parameters for a specific nonlinear process can lead to a substantial increase in electromagnetic emission efficiency. It was found that electromagnetic radiation emerging from the plasma in such a regime is generated near the harmonics of the pump frequency that is determined by the typical eigenfrequency of the beam-driven modes. It was also shown that the peak emission power can reach 5% of the maximal power lost by beam electrons.

  17. Kinetic simulations of ladder climbing by electron plasma waves

    Science.gov (United States)

    Hara, Kentaro; Barth, Ido; Kaminski, Erez; Dodin, I. Y.; Fisch, N. J.

    2017-05-01

    The energy of plasma waves can be moved up and down the spectrum using chirped modulations of plasma parameters, which can be driven by external fields. Depending on whether the wave spectrum is discrete (bounded plasma) or continuous (boundless plasma), this phenomenon is called ladder climbing (LC) or autoresonant acceleration of plasmons. It was first proposed by Barth et al. [Phys. Rev. Lett. 115, 075001 (2015), 10.1103/PhysRevLett.115.075001] based on a linear fluid model. In this paper, LC of electron plasma waves is investigated using fully nonlinear Vlasov-Poisson simulations of collisionless bounded plasma. It is shown that, in agreement with the basic theory, plasmons survive substantial transformations of the spectrum and are destroyed only when their wave numbers become large enough to trigger Landau damping. Since nonlinear effects decrease the damping rate, LC is even more efficient when practiced on structures like quasiperiodic Bernstein-Greene-Kruskal (BGK) waves rather than on Langmuir waves per se.

  18. Alfven waves in a partially ionized two-fluid plasma

    CERN Document Server

    Soler, R; Ballester, J L; Terradas, J

    2013-01-01

    Alfv\\'en waves are a particular class of magnetohydrodynamic waves relevant in many astrophysical and laboratory plasmas. In partially ionized plasmas the dynamics of Alfv\\'en waves is affected by the interaction between ionized and neutral species. Here we study Alfv\\'en waves in a partially ionized plasma from the theoretical point of view using the two-fluid description. We consider that the plasma is composed of an ion-electron fluid and a neutral fluid, which interact by means of particle collisions. To keep our investigation as general as possible we take the neutral-ion collision frequency and the ionization degree as free parameters. First, we perform a normal mode analysis. We find the modification due to neutral-ion collisions of the wave frequencies and study the temporal and spatial attenuation of the waves. In addition, we discuss the presence of cut-off values of the wavelength that constrain the existence of oscillatory standing waves in weakly ionized plasmas. Later, we go beyond the normal mo...

  19. Efficiency and Stimulated Emission in Quarter Wave OLEDS

    CERN Document Server

    Nelson, Mitchell C

    2016-01-01

    Quarter-wave OLEDS are microcavity devices that can operate in the low finesse limit and achieve high efficiency (> 300 lm/W) by using interference to reduce the onset current for the transition to stimulated emission. In this work we study the transition to stimulated emission and compare the kinetics and electrical properties of conventional and quarter-wave devices. We show that suppression of spontaneous emission into the vertical mode can result in a sharp transition to stimulated emission at (\\gamma /eV)I ~ N_se/\\tau_sp where N_se/\\tau_sp is determined by optical parameters, and we find a previously observed electrical signature for the transition where the excited state population becomes fixed at low current density. We then study the role of loss mechanisms in the quarter-wave configuration and conclude with some requirements for practical device.

  20. Scattering of radio frequency waves by turbulence in fusion plasmas

    Science.gov (United States)

    Ram, Abhay K.

    2016-10-01

    In tokamak fusion plasmas, coherent fluctuations in the form of blobs or filaments and incoherent fluctuations due to turbulence are routinely observed in the scrape-off layer. Radio frequency (RF) electromagnetic waves, excited by antenna structures placed near the wall of a tokamak, have to propagate through the scrape-off layer before reaching the core of the plasma. While the effect of fluctuations on RF waves has not been quantified experimentally, there are telltale signs, arising from differences between results from simulations and from experiments, that fluctuations can modify the spectrum of RF waves. Any effect on RF waves in the scrape-off layer can have important experimental consequences. For example, electron cyclotron waves are expected to stabilize the deleterious neoclassical tearing mode (NTM) in ITER. Spectral and polarization changes due to scattering will modify the spatial location and profile of the current driven by the RF waves, thereby affecting the control of NTMs. Pioneering theoretical studies and complementary computer simulations have been pursued to elucidate the impact of fluctuations on RF waves. From the full complement of Maxwell's equations for cold, magnetized plasmas, it is shown that the Poynting flux in the wake of filaments develops spatial structure due to diffraction and shadowing. The uniformity of power flow into the plasma is affected by side-scattering, modifications to the wave spectrum, and coupling to plasma waves other than the incident RF wave. The Snell's law and the Fresnel equations have been reformulated within the context of magnetized plasmas. They are distinctly different from their counterparts in scalar dielectric media, and reveal new and important physical insight into the scattering of RF waves. The Snell's law and Fresnel equations are the basis for the Kirchhoff approximation necessary to determine properties of the scattered waves. Furthermore, this theory is also relevant for studying back

  1. Electromagnetic drift waves dispersion for arbitrarily collisional plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wonjae, E-mail: wol023@ucsd.edu; Krasheninnikov, Sergei I., E-mail: skrash@mae.ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States); Angus, J. R. [Naval Research Laboratory, 4555 Overlook Avenue, Washington, DC 20375 (United States)

    2015-07-15

    The impacts of the electromagnetic effects on resistive and collisionless drift waves are studied. A local linear analysis on an electromagnetic drift-kinetic equation with Bhatnagar-Gross-Krook-like collision operator demonstrates that the model is valid for describing linear growth rates of drift wave instabilities in a wide range of plasma parameters showing convergence to reference models for limiting cases. The wave-particle interactions drive collisionless drift-Alfvén wave instability in low collisionality and high beta plasma regime. The Landau resonance effects not only excite collisionless drift wave modes but also suppress high frequency electron inertia modes observed from an electromagnetic fluid model in collisionless and low beta regime. Considering ion temperature effects, it is found that the impact of finite Larmor radius effects significantly reduces the growth rate of the drift-Alfvén wave instability with synergistic effects of high beta stabilization and Landau resonance.

  2. Surface Waves in the paritally ionized solar plasma slab

    CERN Document Server

    Pandey, B P

    2013-01-01

    The properties of surface waves in the partially ionized, incompressible magnetized plasma slab are investigated in the present work. The waves are affected by the non ideal MHD effects which causes the finite drift of the magnetic field in the medium. When the finite drift of the magnetic field is ignored, the characteristics of the wave propagation in the partially ionized plasma fluid is similar to the ideal MHD except now the propagation properties depend on the fractional ionization of the medium. In the presence of Hall diffusion, the propagation of the sausage and kink surface waves depends on the level of fractional ionization of the medium. When both the Hall and Pedersen diffusion are present in the medium, the waves undergoes damping. For typical solar parameters, waves may damp over few minutes.

  3. Electromagnetic ion cyclotron waves in the plasma depletion layer

    Science.gov (United States)

    Denton, Richard E.; Hudson, Mary K.; Fuselier, Stephen A.; Anderson, Brian J.

    1993-01-01

    Results of a study of the theoretical properties of electromagnetic ion cyclotron (EMIC) waves which occur in the plasma depletion layer are presented. The analysis assumes a homogeneous plasma with the characteristics which were measured by the AMPTE/CCE satellite at 1450-1501 UT on October 5, 1984. Waves were observed in the Pc 1 frequency range below the hydrogen gyrofrequency, and these waves are identified as EMIC waves. The higher-frequency instability is driven by the temperature anisotropy of the H(+) ions, while the lower-frequency instability is driven by the temperature anisotropy of the He(2+) ions. It is argued that the higher-frequency waves will have k roughly parallel to B(0) and will be left-hand polarized, while the lower frequency wave band will have k oblique to B(0) and will be linearly polarized, in agreement with observations.

  4. Surface-wave plasma source with magnetic multicusp fields; Multicusp jiba tojikome hyomenha plasma gen

    Energy Technology Data Exchange (ETDEWEB)

    Tsuda, M.; Ono, K.; Tsuchihashi, M.; Hanazaki, M.; Komemura, T. [Mitsubishi Electric Corp., Tokyo (Japan)

    1998-11-01

    A new-type microwave plasma source has been developed for materials processing. The plasma reactor employed a launcher of azimuthally symmetric surface waves at a frequency of 2.45 GHz and also magnetic multicusp fields around the reactor chamber walls. This configuration yielded high-density (Ne {>=} 10{sup 11}cm{sup -3}) plasmas sustained by surface waves even at low gas pressures below 10 m Torr, following easy plasma ignition by electron cyclotron resonance (ECR) discharges. Electrical and optical diagnostics were made to obtain the plasma properties in Ar. It was shown that a transition from ECR excited to surface-wave excited plasmas occurs under conditions where the plasma electron density exceeds a critical value of Ne-1 times 10{sup 11}cm{sup -3}. 21 refs., 14 figs.

  5. Polar Plasma Wave Investigation Data Analysis in the Extended Mission

    Science.gov (United States)

    Gurnett, Donald A.

    2004-01-01

    The low latitude boundary layer (LLBL) is a region where solar wind momentum and energy is transferred to the magnetosphere. Enhanced "broadband" electric plasma waves from less than 5 Hz to 10(exp 5) Hz and magnetic waves from less than 5 Hz to the electron cyclotron frequency are characteristic of the LLBL. Analyses of Polar plasma waves show that these "broadband" waves are actually discrete electrostatic and electromagnetic modes as well as solitary bipolar pulses (electron holes). It is noted that all wave modes can be generated by approx. 100 eV to approx. 10 keV auroral electrons and protons. We will review wave-particle interactions, with focus on cross-diffusion rates and the contributions of such interactions toward the formation of the boundary layer. In summary, we will present a scenario where the global solar wind-magnetosphere interaction is responsible for the auroral zone particle beams, and hence for the generation of plasma waves and the formation of the boundary layer. It is speculated that all planetary magnetospheres will have boundary layers and they will be characterized by similar currents and plasma wave modes.

  6. Surface waves on a quantum plasma half-space

    CERN Document Server

    Lázár, M; Smolyakov, A

    2007-01-01

    Surface modes are coupled electromagnetic/electrostatic excitations of free electrons near the vacuum-plasma interface and can be excited on a sufficiently dense plasma half-space. They propagate along the surface plane and decay in either sides of the boundary. In such dense plasma models, which are of interest in electronic signal transmission or in some astrophysical applications, the dynamics of the electrons is certainly affected by the quantum effects. Thus, the dispersion relation for the surface wave on a quantum electron plasma half-space is derived by employing the quantum hydrodynamical (QHD) and Maxwell-Poison equations. The QHD include quantum forces involving the Fermi electron temperature and the quantum Bohm potential. It is found that, at room temperature, the quantum effects are mainly relevant for the electrostatic surface plasma waves in a dense gold metallic plasma.

  7. Surface plasma waves over bismuth–vacuum interface

    Indian Academy of Sciences (India)

    Ashim P Jain; J Parashar

    2003-09-01

    A surface plasma wave (SPW) over bismuth–vacuum interface has a signature of mass anisotropy of free electrons. For SPW propagation along the trigonal axis there is no birefringence. The frequency cutoff of SPW cutoff=$_{p}/\\sqrt{2(_{L}+)}$ lies in the far infrared region and can be accessed using free electron laser. The damping rate of waves at low temperatures is low. The surface plasma wave may be excited by an electron beam of current ∼ 100 mA propagating parallel to the interface in its close proximity.

  8. Finite Amplitude Electron Plasma Waves in a Cylindrical Waveguide

    DEFF Research Database (Denmark)

    Juul Rasmussen, Jens

    1978-01-01

    The nonlinear behaviour of the electron plasma wave propagating in a cylindrical plasma waveguide immersed in an infinite axial magnetic field is investigated using the Krylov-Bogoliubov-Mitropolsky perturbation method, by means of which is deduced the nonlinear Schrodinger equation governing...... the long-time slow modulation of the wave amplitude. From this equation the amplitude-dependent frequency and wavenumber shifts are calculated, and it is found that the electron waves with short wavelengths are modulationally unstable with respect to long-wavelength, low-frequency perturbations...

  9. Enhanced field emission of plasma treated multilayer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Khare, Ruchita T.; More, Mahendra A. [Department of Physics, Center for Advanced Studies in Material Science and Condensed Matter Physics, S P Pune University, Pune 411007 (India); Gelamo, Rogerio V. [Instituto de Ciências Tecnológicas e Exatas, UFTM, Uberaba, Minas Gerais 38025-180 (Brazil); Late, Dattatray J., E-mail: dj.late@ncl.res.in, E-mail: csrout@iitbbs.ac.in [Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, Maharashtra (India); Rout, Chandra Sekhar, E-mail: dj.late@ncl.res.in, E-mail: csrout@iitbbs.ac.in [School of Basic Sciences, Indian Institute of Technology, Bhubaneswar 751013, Odisha (India)

    2015-09-21

    Electron emission properties of multilayer graphene (MLG) prepared by a facile exfoliation technique have been studied. Effect of CO{sub 2} Ar, N{sub 2}, plasma treatment was studied using Raman spectroscopy and investigated for field emission based application. The CO{sub 2} plasma treated multilayer graphene shows an enhanced field emission behavior with a low turn on field of 0.18 V/μm and high emission current density of 1.89 mA/cm{sup 2} at an applied field of 0.35 V/μm. Further the plasma treated MLG exhibits excellent current stability at a lower and higher emission current value.

  10. Nonlinear interactions between electromagnetic waves and electron plasma oscillations in quantum plasmas.

    Science.gov (United States)

    Shukla, P K; Eliasson, B

    2007-08-31

    We consider nonlinear interactions between intense circularly polarized electromagnetic (CPEM) waves and electron plasma oscillations (EPOs) in a dense quantum plasma, taking into account the electron density response in the presence of the relativistic ponderomotive force and mass increase in the CPEM wave fields. The dynamics of the CPEM waves and EPOs is governed by the two coupled nonlinear Schrödinger equations and Poisson's equation. The nonlinear equations admit the modulational instability of an intense CPEM pump wave against EPOs, leading to the formation and trapping of localized CPEM wave pipes in the electron density hole that is associated with a positive potential distribution in our dense plasma. The relevance of our investigation to the next generation intense laser-solid density plasma interaction experiments is discussed.

  11. Electrostatic solitary waves in dusty pair-ion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Misra, A. P. [Department of Mathematics, Siksha Bhavana, Visva-Bharati University, Santiniketan-731 235, West Bengal (India); Adhikary, N. C. [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati-781035, Assam (India)

    2013-10-15

    The propagation of electrostatic waves in an unmagnetized collisionless pair-ion plasma with immobile positively charged dusts is studied for both large- and small-amplitude perturbations. Using a two-fluid model for pair-ions, it is shown that there appear two linear ion modes, namely the “fast” and “slow” waves in dusty pair-ion plasmas. The properties of these wave modes are studied with different mass (m) and temperature (T) ratios of negative to positive ions, as well as the effects of immobile charged dusts (δ). For large-amplitude waves, the pseudopotential approach is performed, whereas the standard reductive perturbation technique is used to study the small-amplitude Korteweg-de Vries (KdV) solitons. The profiles of the pseudopotential, the large amplitude solitons as well as the dynamical evolution of KdV solitons, are numerically studied with the system parameters as above. It is found that the pair-ion plasmas with positively charged dusts support the propagation of solitary waves (SWs) with only the negative potential. The results may be useful for the excitation of SWs in laboratory dusty pair-ion plasmas, electron-free industrial plasmas as well as for observation in space plasmas where electron density is negligibly small compared to that of negative ions.

  12. Instability wave control in turbulent jet by plasma actuators

    Science.gov (United States)

    Kopiev, V. F.; Akishev, Y. S.; Belyaev, I. V.; Berezhetskaya, N. K.; Bityurin, V. A.; Faranosov, G. A.; Grushin, M. E.; Klimov, A. I.; Kopiev, V. A.; Kossyi, I. A.; Moralev, I. A.; Ostrikov, N. N.; Taktakishvili, M. I.; Trushkin, N. I.; Zaytsev, M. Yu

    2014-12-01

    Instability waves in the shear layer of turbulent jets are known to be a significant source of jet noise, which makes their suppression important for the aviation industry. In this study we apply plasma actuators in order to control instability waves in the shear layer of a turbulent air jet at atmospheric pressure. Three types of plasma actuators are studied: high-frequency dielectric barrier discharge, slipping surface discharge, and surface barrier corona discharge. Particle image velocimetry measurements of the shear layer demonstrate that the plasma actuators have control authority over instability waves and effectively suppress the instability waves artificially generated in the shear layer. It makes these actuators promising for application in active control systems for jet noise mitigation.

  13. Eulerian simulations of collisional effects on electrostatic plasma waves

    CERN Document Server

    Pezzi, Oreste; Perrone, Denise; Veltri, Pierluigi

    2013-01-01

    The problem of collisions in a plasma is a wide subject with a huge historical literature. In fact, the description of realistic plasmas is a tough problem to attach, both from the theoretical and the numerical point of view, and which requires in general to approximate the original collisional Landau integral by simplified differential operators in reduced dimensionality. In this paper, a Eulerian time-splitting algorithm for the study of the propagation of electrostatic waves in collisional plasmas is presented. Collisions are modeled through one-dimensional operators of the Fokker-Planck type, both in linear and nonlinear form. The accuracy of the numerical code is discussed by comparing the numerical results to the analytical predictions obtained in some limit cases when trying to evaluate the effects of collisions in the phenomenon of wave plasma echo and collisional dissipation of Bernstein-Greene-Kruskal waves. Particular attention is devoted to the study of the nonlinear Dougherty collisional operator...

  14. Surface waves in the magnetized, collisional dusty plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, B. P. [Department of Physics, Astronomy and Research Centre for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney NSW 2109 (Australia); Vladimirov, S. V. [School of Physics, The University of Sydney, Sydney NSW 2006 (Australia); Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan); Metamaterials Laboratory, National Research University of Information Technology, Mechanics, and Optics, St. Petersburg 199034 (Russian Federation); Ishihara, O. [Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan)

    2013-10-15

    The properties of the low frequency surface waves in inhomogeneous, magnetized collisional complex dusty plasma are investigated in this work. The inhomogeneity is modelled by the two distinct regions of the dusty medium with different dust densities. The external magnetic field is assumed to be oriented along the interface dividing the two medium. It is shown that the collisional momentum exchange that is responsible for the relative drift between the plasma particles affects the propagation of the surface waves in the complex plasma via the Hall drift of the magnetic fluctuations. The propagation properties of the sausage and kink waves depend not only on the grain charge and size distribution but also on the ambient plasma thermal conditions.

  15. Low-Frequency Waves in Cold Three-Component Plasmas

    Science.gov (United States)

    Fu, Qiang; Tang, Ying; Zhao, Jinsong; Lu, Jianyong

    2016-09-01

    The dispersion relation and electromagnetic polarization of the plasma waves are comprehensively studied in cold electron, proton, and heavy charged particle plasmas. Three modes are classified as the fast, intermediate, and slow mode waves according to different phase velocities. When plasmas contain positively-charged particles, the fast and intermediate modes can interact at the small propagating angles, whereas the two modes are separate at the large propagating angles. The near-parallel intermediate and slow waves experience the linear polarization, circular polarization, and linear polarization again, with the increasing wave number. The wave number regime corresponding to the above circular polarization shrinks as the propagating angle increases. Moreover, the fast and intermediate modes cause the reverse change of the electromagnetic polarization at the special wave number. While the heavy particles carry the negative charges, the dispersion relations of the fast and intermediate modes are always separate, being independent of the propagating angles. Furthermore, this study gives new expressions of the three resonance frequencies corresponding to the highly-oblique propagation waves in the general three-component plasmas, and shows the dependence of the resonance frequencies on the propagating angle, the concentration of the heavy particle, and the mass ratio among different kinds of particles. supported by National Natural Science Foundation of China (Nos. 11303099, 41531071 and 41574158), and the Youth Innovation Promotion Association CAS

  16. Shock Wave Emissions of a Sonoluminescing Bubble

    CERN Document Server

    Holzfuss, J; Billó, M; Holzfuss, Joachim; Ruggeberg, Matthias; Billo, Andreas

    1998-01-01

    A single bubble in water is excited by a standing ultrasound wave. At high intensity the bubble starts to emit light. Together with the emitted light pulse, a shock wave is generated in the liquid at collapse time. The time-dependent velocity of the outward-travelling shock is measured with an imaging technique. The pressure in the shock and in the bubble is shown to have a lower limit of 5500 bars. Visualization of the shock and the bubble at different phases of the acoustic cycle reveals previously unobserved dynamics during stable and unstable sonoluminescence.

  17. Advanced Accelerators: Particle, Photon and Plasma Wave Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Ronald L. [Florida A & M University, Tallahassee, FL (United States)

    2017-06-29

    The overall objective of this project was to study the acceleration of electrons to very high energies over very short distances based on trapping slowly moving electrons in the fast moving potential wells of large amplitude plasma waves, which have relativistic phase velocities. These relativistic plasma waves, or wakefields, are the basis of table-top accelerators that have been shown to accelerate electrons to the same high energies as kilometer-length linear particle colliders operating using traditional decades-old acceleration techniques. The accelerating electrostatic fields of the relativistic plasma wave accelerators can be as large as GigaVolts/meter, and our goal was to study techniques for remotely measuring these large fields by injecting low energy probe electron beams across the plasma wave and measuring the beam’s deflection. Our method of study was via computer simulations, and these results suggested that the deflection of the probe electron beam was directly proportional to the amplitude of the plasma wave. This is the basis of a proposed diagnostic technique, and numerous studies were performed to determine the effects of changing the electron beam, plasma wave and laser beam parameters. Further simulation studies included copropagating laser beams with the relativistic plasma waves. New interesting results came out of these studies including the prediction that very small scale electron beam bunching occurs, and an anomalous line focusing of the electron beam occurs under certain conditions. These studies were summarized in the dissertation of a graduate student who obtained the Ph.D. in physics. This past research program has motivated ideas for further research to corroborate these results using particle-in-cell simulation tools which will help design a test-of-concept experiment in our laboratory and a scaled up version for testing at a major wakefield accelerator facility.

  18. Fe XVII Emission from Hot, Collisional Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Beiersdorfer, P; Bitter, M; von Goeler, S; Hill, K W

    2004-12-03

    The ratios of the Fe XVII 3s {yields} 2p transitions to that of the dominant 3d {yields} 2p transition measured in high-temperature tokamak plasmas are compared to solar and astrophysical observations. Good agreement is found, indicating that the collisional line formation processes active in opacity-free, low-density, high-temperature laboratory plasmas are a good description of those found in astrophysical plasmas.

  19. Wave-particle and wave-wave interactions in hot plasmas: a French historical point of view

    Science.gov (United States)

    Laval, Guy; Pesme, Denis; Adam, Jean-Claude

    2016-11-01

    The first researches on nuclear fusion for energy applications marked the entrance of hot plasmas into the laboratory. It became necessary to understand the behavior of such plasmas and to learn how to manipulate them. Theoreticians and experimentalists, building on the foundations of empirical laws, had to construct this new plasma physics from first principles and to explain the results of more and more complicated experiments. Along this line, two important topics emerged: wave-particle and wave-wave interactions. Here, their history is recalled as it has been lived by a French team from the end of the sixties to the beginning of the twenty-first century.

  20. Terahertz generation by beating two Langmuir waves in a warm and collisional plasma

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiao-Bo; Qiao, Xin; Cheng, Li-Hong; Tang, Rong-An; Zhang, Ai-Xia; Xue, Ju-Kui, E-mail: xuejk@nwnu.edu.cn [Key Laboratory of Atomic & Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronics Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2015-09-15

    Terahertz (THz) radiation generated by beating of two Langmuir waves in a warm and collisional plasma is discussed theoretically. The critical angle between the two Langmuir waves and the critical wave-length (wave vector) of Langmuir waves for generating THz radiation are obtained analytically. Furthermore, the maximum radiation energy is obtained. We find that the critical angle, the critical wave-length, and the generated radiation energy strongly depend on plasma temperature and wave-length of the Langmuir waves. That is, the THz radiation generated by beating of two Langmuir waves in a warm and collisional plasma can be controlled by adjusting the plasma temperature and the Langmuir wave-length.

  1. Non-linear plasma effects on laser-induced terahertz emission from the atmosphere

    Science.gov (United States)

    Shin, J.-H.; Zhidkov, A.; Jin, Z.; Hosokai, T.; Kodama, R.

    2012-02-01

    Power, spectral characteristics, and angle distribution of terahertz (THz) radiation from air irradiated by a single (ω) or coupled (ω, 2ω) femtosecond laser pulses are analyzed for higher intensities, for which non-linear plasma effects on the pulse propagation become essential, by means of multidimensional particle-in-cell simulations exploiting the self-consistent plasma kinetics. THz radiation is shown to be a result of beat waves generated at ionization front with fundamental and second harmonic waves. At lower intensities, the THz power growth is far faster than the linear; at pulse intensities over I > 1015 W/cm2, the power increases slower than the linear. Along with the forward emission, strong power in around 30o angles occurs at high intensities. Ionization of air results in poor focusing of laser pulses and, therefore, lower efficiency of THz emission.

  2. Bursty emission of whistler waves in association with plasmoid collision

    Directory of Open Access Journals (Sweden)

    K. Fujimoto

    2017-07-01

    Full Text Available A new mechanism to generate whistler waves in the course of collisionless magnetic reconnection is proposed. It is found that intense whistler emissions occur in association with plasmoid collisions. The key processes are strong perpendicular heating of the electrons through a secondary magnetic reconnection during plasmoid collision and the subsequent compression of the ambient magnetic field, leading to whistler instability due to the electron temperature anisotropy. The emissions have a bursty nature, completing in a short time within the ion timescales, as has often been observed in the Earth's magnetosphere. The whistler waves can accelerate the electrons in the parallel direction, contributing to the generation of high-energy electrons. The present study suggests that the bursty emission of whistler waves could be an indicator of plasmoid collisions and the associated particle energization during collisionless magnetic reconnection.

  3. Modeling the emission of high power terahertz radiation using Langmuir wave as a wiggler

    Science.gov (United States)

    Panwar, Jyotsna; Sharma, Suresh C.

    2017-08-01

    The emission of high power terahertz (THz) radiation lying in the range of millimeter to submillimeter wavelengths has been studied analytically using the Langmuir wave as an electrostatic pump wave in the presence of static magnetic field for both finite and infinite geometries. The interaction of two laser beams with the relativistic electron beam leads to velocity modulation of the beam, which then translates into density modulation on traveling through the drift space. The premodulated beam on interacting with the pump wave acquires an oscillatory velocity that couples with the perturbed and modulated beam densities to result in nonlinear current density which helps in evaluating the growth rate and efficiency of the output THz radiation. The beam and plasma wave wiggler parameters are found to influence the growth rate and efficiency of the emitted THz radiation.

  4. Gravitational wave emission from the coalescence of white dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Berro, E [Departament de Fisica Aplicada, Universitat Politecnica de Catalunya, Escola Politecnica Superior de Castelldefels, Avda del Canal OlImpic s/n, 08860 Castelldefels (Spain); Institut d' Estudis Espacials de Catalunya, Ed. Nexus, c/Gran Capita 2, 08034 Barcelona (Spain); Loren-Aguilar, P [Institut d' Estudis Espacials de Catalunya, Ed. Nexus, c/Gran Capita 2, 08034 Barcelona (Spain); Institut de Ciencies de l' Espai (CSIC), Campus UAB, Facultat de Ciencies, Torre C-5, 08193 Bellaterra (Spain); Isern, J [Institut d' Estudis Espacials de Catalunya, Ed. Nexus, c/Gran Capita 2, 08034 Barcelona (Spain); Institut de Ciencies de l' Espai (CSIC), Campus UAB, Facultat de Ciencies, Torre C-5, 08193 Bellaterra (Spain); Pedemonte, A G [Departament de Fisica Aplicada, Universitat Politecnica de Catalunya, Escola Politecnica Superior de Castelldefels, Avda del Canal OlImpic s/n, 08860 Castelldefels (Spain); Guerrero, J [Institut d' Estudis Espacials de Catalunya, Ed. Nexus, c/Gran Capita 2, 08034 Barcelona (Spain); Institut de Ciencies de l' Espai (CSIC), Campus UAB, Facultat de Ciencies, Torre C-5, 08193 Bellaterra (Spain); Lobo, J A [Institut d' Estudis Espacials de Catalunya, Ed. Nexus, c/Gran Capita 2, 08034 Barcelona (Spain); Departament de Fisica Fonamental, Universitat de Barcelona, c/MartI i Franques 1, 08028 Barcelona (Spain)

    2005-05-21

    We have computed the gravitational wave emission arising from the coalescence of several close white dwarf binary systems. In order to do so, we have followed the evolution of such systems using a smoothed particle hydrodynamics code. Here we present some of the results obtained so far, paying special attention to the detectability of the emitted gravitational waves. Within this context, we show which could be the impact of individual merging episodes for LISA.

  5. Shock wave emission during the collapse of cavitation bubbles

    Science.gov (United States)

    Garen, W.; Hegedűs, F.; Kai, Y.; Koch, S.; Meyerer, B.; Neu, W.; Teubner, U.

    2016-07-01

    Shock wave emission induced by intense laser pulses is investigated experimentally. The present work focuses on the conditions of shock wave emission in glycerine and distilled water during the first bubble collapse. Experimental investigations are carried out in liquids as a function of temperature and viscosity. Comparison is made with the theoretical work of Poritsky (Proc 1st US Natl Congress Appl Mech 813-821, 1952) and Brennen (Cavitation and bubble dynamics, Oxford University Press 1995). To the best knowledge of the authors, this is the first experimental verification of those theories.

  6. Vlasov - Maxwell, Self-consistent Electromagnetic Wave Emission Simulations in the Solar Corona

    Science.gov (United States)

    Tsiklauri, David

    2010-12-01

    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 context of solar physics. 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 a 1.5D inhomogeneous plasma with a uniform background magnetic field directed transverse to the density gradient is aperiodically unstable to the Larmor-drift instability. The latter results in a novel effect of generation of electromagnetic emission at plasma frequency. The generated perturbations consist of two parts: i) non-escaping (trapped) Langmuir type oscillations, which are localised in the regions of density inhomogeneity, and are highly filamentary, with the period of appearance of the filaments close to electron plasma frequency in the dense regions; and ii) escaping electromagnetic radiation with phase speeds close to the speed of light. When the density gradient is removed ( i.e. when plasma becomes stable to the Larmor-drift instability) and a low density super-thermal, hot beam is injected along the domain, in the direction perpendicular to the magnetic field, the plasma emission mechanism generates non-escaping Langmuir type oscillations, which in turn generate escaping electromagnetic radiation. It is found that in the spatial location where the beam is injected, standing waves, oscillating at the plasma frequency, are excited. These can be used to interpret the horizontal strips (the narrow-band line emission) observed in some dynamical spectra. Predictions of quasilinear theory are: i) the electron free streaming and ii) the long relaxation time of the beam, in accord with the analytic expressions. These are corroborated via direct, fully-kinetic simulation

  7. Secondary Fast Magnetoacoustic Waves Trapped in Randomly Structured Plasmas

    Science.gov (United States)

    Yuan, Ding; Li, Bo; Walsh, Robert W.

    2016-09-01

    Fast magnetoacoustic waves are an important tool for inferring parameters of the solar atmosphere. We numerically simulate the propagation of fast wave pulses in randomly structured plasmas that mimic the highly inhomogeneous solar corona. A network of secondary waves is formed by a series of partial reflections and transmissions. These secondary waves exhibit quasi-periodicities in both time and space. Since the temporal and spatial periods are related simply through the speed of the fast wave, we quantify the properties of secondary waves by examining the dependence of the average temporal period (\\bar{p}) on the initial pulse width (w 0) and studying the density contrast ({δ }ρ ) and correlation length (L c ) that characterize the randomness of the equilibrium density profiles. For small-amplitude pulses, {δ }ρ does not alter \\bar{p} significantly. Large-amplitude pulses, on the other hand, enhance the density contrast when {δ }ρ is small but have a smoothing effect when {δ }ρ is sufficiently large. We found that \\bar{p} scales linearly with L c and that the scaling factor is larger for a narrower pulse. However, in terms of the absolute values of \\bar{p}, broader pulses generate secondary waves with longer periods, and this effect is stronger in random plasmas with shorter correlation lengths. Secondary waves carry the signatures of both the leading wave pulse and the background plasma. Our study may find applications in magnetohydrodynamic seismology by exploiting the secondary waves detected in the dimming regions after coronal mass ejections or extreme ultraviolet waves.

  8. Investigation on laser accelerators. Plasma beat wave accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Akihiko; Miyamoto, Yasuaki; Hagiwara, Masayoshi; Suzuki, Mitsutoshi; Sudo, Osamu [Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan). Tokai Works

    1998-04-01

    Laser accelerator technology has characteristics of high energy, compact, short pulse and high luminescence{center_dot}low emittance. This means potential many applications in wide ranges of fields as well as high energy and nuclear physics. High power short laser pulses are injected to a plasma in the typical example of laser accelerators. Large electric fields are induced in the plasma. Electrons in the plasma are accelerated with the ponderomotive force of the electric field. The principles of interaction on beat wave, wakefield accelerators, inverse free electron laser and inverse Cherenkov radiation are briefly introduced. The overview of plasma beat wave accelerator study is briefly described on the programs at Chalk River Laboratories(Canada), UCLA(USA), Osaka Univ. (Japan) and Ecole Polytechnique (France). Issues of the plasma beat wave accelerator are discussed from the viewpoint of application. Existing laser technologies of CO{sub 2}, YAG and YFL are available for the present day accelerator technology. An acceleration length of beat wave interaction is limited due to its phase condition. Ideas on multi-staged acceleration using the phasing plasma fiber are introduced. (Y. Tanaka)

  9. Non linear dynamic of Langmuir and electromagnetic waves in space plasmas; Dinamica nao linear de ondas de Langmuir e eletromagneticas em plasmas espaciais

    Energy Technology Data Exchange (ETDEWEB)

    Guede, Jose Ricardo Abalde

    1995-11-01

    The aim of this work is to study the nonlinear dynamics of Langmuir and electromagnetic waves in space plasmas. Firstly, the generalized Zakharov equations are derived which are used to study the hybrid parametric instability involving the generation of daughter Langmuir, electromagnetic and ion-acoustic waves induced by two counter-propagating Langmuir pump waves with different amplitudes based on a coupled dispersion relation. Secondly, starting from the generalized Zakharov equations the linear and nonlinear coupled mode theories of three-wave and four-wave parametric interactions are developed, respectively. In three-waves processes, a Langmuir wave decays into another Langmuir wave and an ion-acoustic wave (electrostatic parametric decay) or into an electromagnetic wave and an ion-acoustic wave (electromagnetic parametric decay). In four-wave (modulational) processes, the interaction involves two wave triplets: in the decay triplet a pump wave couples with a low-frequency wave to generate a Stokes wave, and in the fusion triplets: in the decay triplet a pump wave couples with a low-frequency wave to generate a Stokes wave, and in the fusion triplet the coupling of a pump wave with a low-frequency wave generate an anti-Stokes wave. These modulational processes are convective and resonant processes wherein the low-frequency modes are Eigenmodes of plasma and are known as the stimulated modulational processes. Four such processes are investigated in this thesis: two with Langmuir pump waves (electrostatic and hybrid stimulated modulation processes) and the other two with electromagnetic pump waves (stimulated modulation Brillouin scattering and electromagnetic stimulated modulation process). Applications of the theoretical results in space plasmas are discussed. In particular, it is shown that the electrostatic and electromagnetic parametric decay processes of Langmuir waves can model the generation and modulation of radio emissions and Langmuir waves in the

  10. Ion-acoustic cnoidal waves in a quantum plasma

    CERN Document Server

    Mahmood, Shahzad

    2016-01-01

    Nonlinear ion-acoustic cnoidal wave structures are studied in an unmagnetized quantum plasma. Using the reductive perturbation method, a Korteweg-de Vries equation is derived for appropriate boundary conditions and nonlinear periodic wave solutions are obtained. The corresponding analytical solution and numerical plots of the ion-acoustic cnoidal waves and solitons in the phase plane are presented using the Sagdeev pseudo-potential approach. The variations in the nonlinear potential of the ion-acoustic cnoidal waves are studied at different values of quantum parameter $H_{e}$ which is the ratio of electron plasmon energy to electron Fermi energy defined for degenerate electrons. It is found that both compressive and rarefactive ion-acoustic cnoidal wave structures are formed depending on the value of the quantum parameter. The dependence of the wavelength and frequency on nonlinear wave amplitude is also presented.

  11. Spatiotemporal synchronization of drift waves in a magnetron sputtering plasma

    CERN Document Server

    Martines, E; Cavazzana, R; Adámek, J; Antoni, V; Serianni, G; Spolaore, M; Vianello, N

    2014-01-01

    A feedforward scheme is applied for drift waves control in a magnetized magnetron sputtering plasma. A system of driven electrodes collecting electron current in a limited region of the explored plasma is used to interact with unstable drift waves. Drift waves actually appear as electrostatic modes characterized by discrete wavelengths of the order of few centimeters and frequencies of about 100 kHz. The effect of external quasi-periodic, both in time and space, travelling perturbations is studied. Particular emphasis is given to the role played by the phase relation between the natural and the imposed fluctuations. It is observed that it is possible by means of localized electrodes, collecting currents which are negligible with respect to those flowing in the plasma, to transfer energy to one single mode and to reduce that associated to the others. Due to the weakness of the external action, only partial control has been achieved.

  12. Some notes on ideology of waves in plasmas

    CERN Document Server

    Soshnikov, V N

    2002-01-01

    Our last three papers provide an occasion to make some brief notes on ideology of waves in plasmas and to rehabilitate Vlasov prescription to calculate relevant logarithmically divergent integrals in the principal value sense. In this approach asymptotical solutions of plasma oscillations are selected according to self-consistent boundary physical conditions. Landau damping is absent in this case by definition. Boundary electrical field together with conditions of absence of unphysical backward and kinematical waves define single-valued dependence of boundary distribution function on electron velocity \\vec{v} in the case of transversal waves and on the surface break of the normal electrical field in the case of longitudinal oscillations. We have proposed physically more justified modified iteration procedure of collisional damping calculation and demonstrated some results of damping decrements calculations in a low-collision electron-ion plasma. Dispersion smearing of both longitudinal and transversal high-fr...

  13. 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.

  14. Nonlinear dynamics of Airy-vortex 3D wave packets: emission of vortex light waves.

    Science.gov (United States)

    Driben, Rodislav; Meier, Torsten

    2014-10-01

    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. Because of 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 nonzero topological charges. Wave packets carrying angular momentum are found to be much more resistant to the rapid collapse.

  15. Effect of the three-dimensional structure of laser emission on the dynamics of low-threshold optical breakdown plasmas

    Science.gov (United States)

    Anisimov, V. N.; Arutiunian, R. V.; Bol'Shov, L. A.; Derkach, O. N.; Kanevskii, M. F.

    1989-03-01

    The effect of the transverse structure of pulsed CO2 laser emission on the dynamics of laser-induced detonation waves propagating from a metal surface and on plasma transparency recovery is investigated theoretically and experimentally. Particular attention is given to breakdown initiation near the surface. It is suggested that the inclusion of refraction in the plasma into a self-consistent numerical mode is essential for the adequate quantitative description of experimental data on the interaction of laser emission with low-threshold optical breakdown plasmas.

  16. Temporal structure of double plasma frequency emission of thin beam-heated plasma

    Energy Technology Data Exchange (ETDEWEB)

    Postupaev, V. V.; Ivanov, I. A.; Arzhannikov, A. V.; Vyacheslavov, L. N. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 2 Pirogova st., 630090 Novosibirsk (Russian Federation); Burdakov, A. V.; Polosatkin, S. V. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, 630090 Novosibirsk (Russian Federation); Novosibirsk State Technical University, 20 Karl Marks Avenue, 630092 Novosibirsk (Russian Federation); Sklyarov, V. F.; Gavrilenko, D. Ye.; Kandaurov, I. V.; Kurkuchekov, V. V.; Mekler, K. I.; Popov, S. S.; Rovenskikh, A. F.; Sudnikov, A. V.; Sulyaev, Yu. S.; Trunev, Yu. A. [Budker Institute of Nuclear Physics, 11 Lavrentjev Avenue, 630090 Novosibirsk (Russian Federation); Kasatov, A. A. [Novosibirsk State University, 2 Pirogova st., 630090 Novosibirsk (Russian Federation)

    2013-09-15

    In the work presented here dynamics of spiky microwave emission of a beam-heated plasma near the double plasma frequency in ∼100 GHz band was studied. The plasma is heated by 80 keV, ∼2 MW, sub-ms electron beam that is injected into the multiple-mirror trap GOL-3. The beam-heated plasma diameter is of the order of the emitted wavelength. Modulation of individual emission spikes in the microwave radiation is found. The radiation dynamics observed can be attributed to a small number of compact emitting zones that are periodically distorted.

  17. Study on the electromagnetic waves propagation characteristics in partially ionized plasma slabs

    Directory of Open Access Journals (Sweden)

    Zhi-Bin Wang

    2016-05-01

    Full Text Available Propagation characteristics of electromagnetic (EM waves in partially ionized plasma slabs are studied in this paper. Such features are significant to applications in plasma antennas, blackout of re-entry flying vehicles, wave energy injection to plasmas, and etc. We in this paper developed a theoretical model of EM wave propagation perpendicular to a plasma slab with a one-dimensional density inhomogeneity along propagation direction to investigate essential characteristics of EM wave propagation in nonuniform plasmas. Particularly, the EM wave propagation in sub-wavelength plasma slabs, where the geometric optics approximation fails, is studied and in comparison with thicker slabs where the geometric optics approximation applies. The influences of both plasma and collisional frequencies, as well as the width of the plasma slab, on the EM wave propagation characteristics are discussed. The results can help the further understanding of propagation behaviours of EM waves in nonuniform plasma, and applications of the interactions between EM waves and plasmas.

  18. Solar Wind Strahl Broadening by Self-Generated Plasma Waves

    Science.gov (United States)

    Pavan, J.; Vinas, A. F.; Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.

    2013-01-01

    This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.

  19. Accumulative coupling between magnetized tenuous plasma and gravitational waves

    Science.gov (United States)

    Zhang, Fan

    2016-07-01

    We explicitly compute the plasma wave (PW) induced by a plane gravitational wave (GW) traveling through a region of strongly magnetized plasma, governed by force-free electrodynamics. The PW comoves with the GW and absorbs its energy to grow over time, creating an essentially force-free counterpart to the inverse-Gertsenshtein effect. The time-averaged Poynting flux of the induced PW is comparable to the vacuum case, but the associated current may offer a more sensitive alternative to photodetection when designing experiments for detecting/constraining high-frequency gravitational waves. Aside from the exact solutions, we also offer an analysis of the general properties of the GW to PW conversion process, which should find use when evaluating electromagnetic counterparts to astrophysical gravitational waves that are generated directly by the latter as a second-order phenomenon.

  20. Accumulative coupling between magnetized tenuous plasma and gravitational waves

    CERN Document Server

    Zhang, Fan

    2016-01-01

    We explicitly compute the plasma wave (PW) induced by a plane gravitational wave (GW) travelling through a region of strongly magnetized plasma, governed by force-free electrodynamics. The PW co-moves with the GW and absorbs its energy to grow over time, creating an essentially force-free counterpart to the inverse-Gertsenshtein effect. The time-averaged Poynting flux of the induced PW is comparable to the vacuum case, but the associated current may offer a more sensitive alternative to photodetection when designing experiments for detecting/constraining high frequency gravitational waves. Aside from the exact solutions, we also offer an analysis of the general properties of the GW to PW conversion process, which should find use when evaluating electromagnetic counterparts to astrophysical gravitational waves, that are generated directly by the latter as a second order phenomenon.

  1. Electromagnetic waves in a magnetized plasma near the critical surface

    Energy Technology Data Exchange (ETDEWEB)

    Timofeev, Aleksandr V [Russian Research Centre ' Kurchatov Institute' , Moscow (Russian Federation)

    2004-06-30

    Electromagnetic waves in a plasma in a magnetic field give rise to enhanced refraction, produce a change in polarization, and cause electromagnetic energy to flow from one wave mode to another when propagating near the critical surface (CS), the one where the electron Langmuir frequency is equal to the wave frequency. A simple unified model of all phenomena taking place near the CS is proposed. These phenomena are due to electromagnetic waves linearly interacting with electron Langmuir oscillations which are localized at the CS in a cold plasma. This interaction manifests itself most strikingly in electron Langmuir oscillation energy escaping directly into a vacuum in the form of electromagnetic radiation. (reviews of topical problems)

  2. Full-wave solution of short impulses in inhomogeneous plasma

    Indian Academy of Sciences (India)

    Orsolya E Ferencz

    2005-02-01

    In this paper the problem of real impulse propagation in arbitrarily inhomogeneous media will be presented on a fundamentally new, general, theoretical way. The general problem of wave propagation of monochromatic signals in inhomogeneous media was enlightened in [1]. The earlier theoretical models for spatial inhomogeneities have some errors regarding the structure of the resultant signal originated from backward and forward propagating parts. The application of the method of inhomogeneous basic modes (MIBM) and the complete full-wave solution of arbitrarily shaped non-monochromatic plane waves in plasmas made it possible to obtain a better description of the problem, on a fully analytical way, directly from Maxwell's equations. The model investigated in this paper is inhomogeneous of arbitrary order (while the wave pattern can exist), anisotropic (magnetized), linear, cold plasma, in which the gradient of the one-dimensional spatial inhomogeneity is parallel to the direction of propagation.

  3. Theoretical and Experimental Study of Scattering of a Plane Wave by an Inhomogeneous Plasma Sphere

    Institute of Scientific and Technical Information of China (English)

    SONG Fa-Lun; CAO Jin-Xiang; WANG Ge; WANG Yan; ZHU Ying; ZHU Jian; WANG Liang; NIU Tian-Ye

    2006-01-01

    @@ Scattering of electromagnetic waves by an inhomogeneous plasma sphere has been studied theoretically and experimentally. The offset angles of electromagnetic waves caused by the plasma sphere have been observed experimentally. The effects of the electromagnetic wave frequency and plasma density on the offset angle are discussed. The plasma density is estimated with the offset angle.

  4. A large volume uniform plasma generator for the experiments of electromagnetic wave propagation in plasma

    Energy Technology Data Exchange (ETDEWEB)

    Yang Min; Li Xiaoping; Xie Kai; Liu Donglin [School of Electronical and Mechanical Engineering, Xidian University, Xi' an Shaanxi 710071 (China); Liu Yanming [School of Telecommunications Engineering, Xidian University, Xi' an Shaanxi 710071 (China)

    2013-01-15

    A large volume uniform plasma generator is proposed for the experiments of electromagnetic (EM) wave propagation in plasma, to reproduce a 'black out' phenomenon with long duration in an environment of the ordinary laboratory. The plasma generator achieves a controllable approximate uniform plasma in volume of 260 mm Multiplication-Sign 260 mm Multiplication-Sign 180 mm without the magnetic confinement. The plasma is produced by the glow discharge, and the special discharge structure is built to bring a steady approximate uniform plasma environment in the electromagnetic wave propagation path without any other barriers. In addition, the electron density and luminosity distributions of plasma under different discharge conditions were diagnosed and experimentally investigated. Both the electron density and the plasma uniformity are directly proportional to the input power and in roughly reverse proportion to the gas pressure in the chamber. Furthermore, the experiments of electromagnetic wave propagation in plasma are conducted in this plasma generator. Blackout phenomena at GPS signal are observed under this system and the measured attenuation curve is of reasonable agreement with the theoretical one, which suggests the effectiveness of the proposed method.

  5. Effect of bremsstrahlung radiation emission on fast electrons in plasmas

    Science.gov (United States)

    Embréus, O.; Stahl, A.; Fülöp, T.

    2016-09-01

    Bremsstrahlung radiation emission is an important energy loss mechanism for energetic electrons in plasmas. In this paper we investigate the effect of spontaneous bremsstrahlung emission on the momentum-space structure of the electron distribution, fully accounting for the emission of finite-energy photons by modeling the bremsstrahlung interactions with a Boltzmann collision operator. We find that electrons accelerated by electric fields can reach significantly higher energies than predicted by the commonly used radiative stopping-power model. Furthermore, we show that the emission of soft photons can contribute significantly to the dynamics of electrons with an anisotropic distribution by causing pitch-angle scattering at a rate that increases with energy.

  6. Effect of bremsstrahlung radiation emission on fast electrons in plasmas

    CERN Document Server

    Embréus, Ola; Fülöp, Tünde

    2016-01-01

    Bremsstrahlung radiation emission is an important energy loss mechanism for energetic electrons in plasmas. In this paper we investigate the effect of spontaneous bremsstrahlung emission on the momentum-space structure of the electron distribution, fully accounting for the emission of finite-energy photons. We find that electrons accelerated by electric fields can reach significantly higher energies than what is expected from energy-loss considerations. Furthermore, we show that the emission of soft photons can contribute significantly to the dynamics of electrons with an anisotropic distribution.

  7. Laser-driven plasma waves in capillary tubes.

    Science.gov (United States)

    Wojda, F; Cassou, K; Genoud, G; Burza, M; Glinec, Y; Lundh, O; Persson, A; Vieux, G; Brunetti, E; Shanks, R P; Jaroszynski, D; Andreev, N E; Wahlström, C-G; Cros, B

    2009-12-01

    The excitation of plasma waves over a length of up to 8 cm is demonstrated using laser guiding of intense laser pulses through hydrogen-filled glass capillary tubes. The plasma waves are diagnosed by spectral analysis of the transmitted laser radiation. The dependence of the spectral redshift-measured as a function of filling pressure, capillary tube length, and incident laser energy-is in excellent agreement with simulation results. The longitudinal accelerating field inferred from the simulations is in the range of 1-10 GV/m.

  8. On the rogue wave propagation in ion pair superthermal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Abdelwahed, H. G., E-mail: hgomaa-eg@yahoo.com, E-mail: hgomaa-eg@mans.edu.eg; Zahran, M. A. [Physics Department, College of Sciences and Humanities Studies Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj (Saudi Arabia); Theoretical Physics Group, Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt); El-Shewy, E. K., E-mail: emadshewy@yahoo.com; Elwakil, S. A. [Theoretical Physics Group, Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt)

    2016-02-15

    Effects of superthermal electron on the features of nonlinear acoustic waves in unmagnetized collisionless ion pair plasma with superthermal electrons have been examined. The system equations are reduced in the form of the nonlinear Schrodinger equation. The rogue wave characteristics dependences on the ionic density ratio (ν = n{sub –0}/n{sub +0}), ionic mass ratio (Q = m{sub +}/m{sub −}), and superthermality index (κ) are investigated. It is worth mentioning that the results present in this work could be applicable in the Earth's ionosphere plasmas.

  9. Generalized dispersive wave emission in nonlinear fiber optics.

    Science.gov (United States)

    Webb, K E; Xu, Y Q; Erkintalo, M; Murdoch, S G

    2013-01-15

    We show that the emission of dispersive waves in nonlinear fiber optics is not limited to soliton-like pulses propagating in the anomalous dispersion regime. We demonstrate, both numerically and experimentally, that pulses propagating in the normal dispersion regime can excite resonant dispersive radiation across the zero-dispersion wavelength into the anomalous regime.

  10. Refraction of VHF radio waves in artificial plasma formations

    Science.gov (United States)

    Kashirin, A. I.; Kliueva, N. M.; Mikhailik, P. P.; Chkalov, V. G.

    1991-09-01

    The defocusing refraction of VHF waves during the radio occultation of artificial plasma clouds in the ionosphere is calculated in the framework of the geometrical-optics approximation. The possibility of determining the main cloud parameters from characteristic power variations of the received radio waves in the case of a monotonic change in the sighting parameter during the experiment is demonstrated. Results of a rocket experiment implementing this method are presented.

  11. Transport of time-varying plasma currents by whistler wave packets

    Science.gov (United States)

    Stenzel, R. L.; Urrutia, J. M.; Rousculp, C.

    1992-01-01

    The relationship between pulsed currents and electromagnetic waves is examined in a regime characterized by electron MHD. Pulsed currents are generated by (1) collection/emission of charged particles by/from biased electrodes and (2) induction of currents by time-varying and moving magnetic fields. Pulsed currents are observed to propagate at the speed of whistler wave packets. Their field structure forms ropelike configurations which are electromagnetically force-free. Moving sources induce 'eddy' currents which excite waves and form Cerenkov-like whistler 'wings'. The radiation patterns of moving magnetic antennas and electrodynamic tethers are investigated. Nonlinear effects of large-amplitude, antenna-launched whistler pulses are observed. These involve a new modulational instability in which a channel of high conductivity which permits the wave/currents to penetrate deeply into a collisional plasma is formed.

  12. Collisionless damping of electron waves in non-Maxwellian plasma

    OpenAIRE

    Soshnikov, V. N.

    2007-01-01

    In this paper we have criticized the so-called Landau damping theory. We have analyzed solutions of the standard dispersion equations for longitudinal (electric) and transversal (electromagnetic and electron) waves in half-infinite slab of the uniform collisionless plasmas with non-Maxwellian and Maxwellian-like electron energy distribution functions. One considered the most typical cases of both the delta-function type distribution function (the plasma stream with monochromatic electrons) an...

  13. Phase conjugation by four-wave mixing in inhomogeneous plasmas

    Science.gov (United States)

    Williams, Edward A.; Lininger, Diana M.; Goldman, Martin V.

    1989-01-01

    The effects of density, temperature, and velocity gradients on four-wave mixing (FWM) in a plasma are investigated. A fluid model is used in which the stimulated Brillouin terms are included, but pump depletion is neglected. The steady state phase conjugate reflectivity and signal transmission coefficients are calculated and discussed for both degenerate and resonant FWM. The substantial effects of inhomogeneity on the use of FWM as a plasma diagnostic are discussed.

  14. Electron plasma wave filamentation in the kinetic regime

    Science.gov (United States)

    Lushnikov, Pavel; Rose, Harvey; Silantyev, Denis

    2016-10-01

    We consider nonlinear electron plasma wave (EPW) dynamics in the kinetic wavenumber regime, 0.25 Bernstein-Greene-Kruskal (BGK) mode. Transverse perturbations of any of these initial conditions grow with time eventually producing strongly nonlinear filamentation followed by plasma turbulence. We compared these simulations with the theoretical results on growth rates of the transverse instability BGK mode showing the satisfactory agreement. Supported by the New Mexico Consortium and NSF DMS-1412140.

  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 $kwaves 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. Plasma characterization using ultraviolet Thomson scattering from ion-acoustic and electron plasma waves (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Follett, R. K., E-mail: rfollett@lle.rochester.edu; Delettrez, J. A.; Edgell, D. H.; Henchen, R. J.; Katz, J.; Myatt, J. F.; Froula, D. H. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States)

    2016-11-15

    Collective Thomson scattering is a technique for measuring the plasma conditions in laser-plasma experiments. Simultaneous measurements of ion-acoustic and electron plasma-wave spectra were obtained using a 263.25-nm Thomson-scattering probe beam. A fully reflective collection system was used to record light scattered from electron plasma waves at electron densities greater than 10{sup 21} cm{sup −3}, which produced scattering peaks near 200 nm. An accurate analysis of the experimental Thomson-scattering spectra required accounting for plasma gradients, instrument sensitivity, optical effects, and background radiation. Practical techniques for including these effects when fitting Thomson-scattering spectra are presented and applied to the measured spectra to show the improvements in plasma characterization.

  17. Plasma characterization using ultraviolet Thomson scattering from ion-acoustic and electron plasma waves (invited)

    Science.gov (United States)

    Follett, R. K.; Delettrez, J. A.; Edgell, D. H.; Henchen, R. J.; Katz, J.; Myatt, J. F.; Froula, D. H.

    2016-11-01

    Collective Thomson scattering is a technique for measuring the plasma conditions in laser-plasma experiments. Simultaneous measurements of ion-acoustic and electron plasma-wave spectra were obtained using a 263.25-nm Thomson-scattering probe beam. A fully reflective collection system was used to record light scattered from electron plasma waves at electron densities greater than 1021 cm-3, which produced scattering peaks near 200 nm. An accurate analysis of the experimental Thomson-scattering spectra required accounting for plasma gradients, instrument sensitivity, optical effects, and background radiation. Practical techniques for including these effects when fitting Thomson-scattering spectra are presented and applied to the measured spectra to show the improvements in plasma characterization.

  18. Computational study of nonlinear plasma waves: 1: Simulation model and monochromatic wave propagation

    Science.gov (United States)

    Matda, Y.; Crawford, F. W.

    1974-01-01

    An economical low noise plasma simulation model is applied to a series of problems associated with electrostatic wave propagation in a one-dimensional, collisionless, Maxwellian plasma, in the absence of magnetic field. The model is described and tested, first in the absence of an applied signal, and then with a small amplitude perturbation, to establish the low noise features and to verify the theoretical linear dispersion relation at wave energy levels as low as 0.000,001 of the plasma thermal energy. The method is then used to study propagation of an essentially monochromatic plane wave. Results on amplitude oscillation and nonlinear frequency shift are compared with available theories. The additional phenomena of sideband instability and satellite growth, stimulated by large amplitude wave propagation and the resulting particle trapping, are described.

  19. Degenerate mixing of plasma waves on cold, magnetized single-species plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, M. W.; O' Neil, T. M.; Dubin, D. H. E.; Gould, R. W. [Physics Department, University of California at San Diego, La Jolla, California 92093 (United States)

    2011-10-15

    In the cold-fluid dispersion relation {omega}={omega}{sub p}/[1+(k{sub perpendicular}/k{sub z}){sup 2}]{sup 1/2} for Trivelpiece-Gould waves on an infinitely long magnetized plasma cylinder, the transverse and axial wavenumbers appear only in the combination k{sub perpendicular}/k{sub z}. As a result, for any frequency {omega}<{omega}{sub p}, there are infinitely many degenerate waves, all having the same value of k{sub perpendicular}/k{sub z}. On a cold finite-length plasma column, these degenerate waves reflect into one another at the ends; thus, each standing-wave normal mode of the bounded plasma is a mixture of many degenerate waves, not a single standing wave as is often assumed. A striking feature of the many-wave modes is that the short-wavelength waves often add constructively along resonance cones given by dz/dr={+-}({omega}{sub p}{sup 2}/{omega}{sup 2}-1){sup 1/2}. Also, the presence of short wavelengths in the admixture for a predominantly long-wavelength mode enhances the viscous damping beyond what the single-wave approximation would predict. Here, numerical solutions are obtained for modes of a cylindrical plasma column with rounded ends. Exploiting the fact that the modes of a spheroidal plasma are known analytically (the Dubin modes), a perturbation analysis is used to investigate the mixing of low-order, nearly degenerate Dubin modes caused by small deformations of a plasma spheroid.

  20. Conversion of electrostatic upper hybrid emissions to electromagnetic O and X mode waves in the Earth's magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Budden, K.G.; Jones, D.

    1987-02-01

    The linear conversion of electrostatic upper hybrid emissions via the Z mode to electromagnetic ordinary (O) mode waves has for some time been invoked for the source of Terrestrial and Saturnian myriametric and Jovian kilometric radiations. The conversion occurs by virtue of the emissions' propagation in concentration gradients, and for it to be efficient it is necessary for the gradient to be normal to the ambient magnetic field. Suitable concentration gradients are believed to occur at the plasmapause and at the magnetopause. Ray theory predicts only O mode production whereas full wave theory in a cold plasma shows that both O and X (extraordinary) mode are produced, their relative intensities depending on the plasma parameters. Full wave theory in a warm plasma, besides yielding more accurate information on the O and X modes also provides an insight into the effect of conversion on the source plasma wave. Results obtained from these three levels of theory are compared using plasma parameters derived from wave experiments on spacecraft.

  1. The incomplete plasma dispersion function: properties and application to waves in bounded plasmas

    OpenAIRE

    Baalrud, Scott D.

    2013-01-01

    The incomplete plasma dispersion function is a generalization of the plasma dispersion function in which the defining integral spans a semi-infinite, rather than infinite, domain. It is useful for describing the linear dielectric response and wave dispersion in non-Maxwellian plasmas when the distribution functions can be approximated as Maxwellian over finite, or semi-infinite, intervals in velocity phase-space. A ubiquitous example is the depleted Maxwellian electron distribution found near...

  2. Evolution of Modulated Dispersive Electron Waves in a Plasma

    DEFF Research Database (Denmark)

    Sugai, H.; Lynov, Jens-Peter; Michelsen, Poul

    1979-01-01

    The linear propagation of amplitude-modulated electron waves was examined in a low-density Q-machine plasma. Three effects of the strong dispersion on the modulated wave have been demonstrated: (i) a wavepacket expands along its direction of propagation, followed by a shift of the frequency through...... the wavepacket, (ii) the number of oscillations in the temporally observed packet is not identical with that in the spatially observed packet and (iii) continuously modulated waves exhibit recurrence of modulation. The experimental results agree with both a simple analysis based on the Schrodinger equation...

  3. Statistical behavior of foreshock Langmuir waves observed by the Cluster wideband data plasma wave receiver

    Directory of Open Access Journals (Sweden)

    K. Sigsbee

    2004-07-01

    Full Text Available We present the statistics of Langmuir wave amplitudes in the Earth's foreshock using Cluster Wideband Data (WBD Plasma Wave Receiver electric field waveforms from spacecraft 2, 3 and 4 on 26 March 2002. The largest amplitude Langmuir waves were observed by Cluster near the boundary between the foreshock and solar wind, in agreement with earlier studies. The characteristics of the waves were similar for all three spacecraft, suggesting that variations in foreshock structure must occur on scales greater than the 50-100km spacecraft separations. The electric field amplitude probability distributions constructed using waveforms from the Cluster WBD Plasma Wave Receiver generally followed the log-normal statistics predicted by stochastic growth theory for the event studied. Comparison with WBD receiver data from 17 February 2002, when spacecraft 4 was set in a special manual gain mode, suggests non-optimal auto-ranging of the instrument may have had some influence on the statistics.

  4. Plasma wave instabilities in nonequilibrium graphene

    DEFF Research Database (Denmark)

    Aryal, Chinta M.; Hu, Ben Yu-Kuang; Jauho, Antti-Pekka

    2016-01-01

    We study two-stream instabilities in a nonequilibrium system in which a stream of electrons is injected into doped graphene. As with equivalent nonequilibrium parabolic band systems, we find that the graphene systems can support unstable charge-density waves whose amplitudes grow with time. We...... of the injected electrons that maximizes the growth rate increases with increasing | q |. We compare the range and strength of the instability in graphene to that of two- and three-dimensional parabolic band systems....

  5. Estimation of Plasma Density by Surface Plasmons for Surface-Wave Plasmas

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhao-Quan; LIU Ming-Hai; LAN Chao-Hui; CHEN Wei; LUO Zhi-Qing; HU Xi-Wei

    2008-01-01

    @@ An estimation method of plasma density based on surface plasmons theory for surface-wave plasmas is proposed. The number of standing-wave is obtained directly from the discharge image, and the propagation constant is calculated with the trim size of the apparatus in this method, then plasma density can be determined with the value of 9.1 × 1017 m-3. Plasma density is measured using a Langmuir probe, the value is 8.1 × 1017 m-3 which is very close to the predicted value of surface plasmons theory. Numerical simulation is used to check the number of standing-wave by the finite-difference time-domain (FDTD) method also. All results are compatible both of theoretical analysis and experimental measurement.

  6. On- and off-axis spectral emission features from laser-produced gas breakdown plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Harilal, S. S.; Skrodzki, P. J.; Miloshevsky, A.; Brumfield, B. E.; Phillips, M. C.; Miloshevsky, G.

    2017-06-01

    Laser-heated gas breakdown plasmas or sparks emit profoundly in the ultraviolet and visible region of the electromagnetic spectrum with contributions from ionic, atomic, and molecular species. Laser created kernels expand into a cold ambient with high velocities during its early lifetime followed by confinement of the plasma kernel and eventually collapse. However, the plasma kernels produced during laser breakdown of gases are also capable of exciting and ionizing the surrounding ambient medium. Two mechanisms can be responsible for excitation and ionization of surrounding ambient: viz. photoexcitation and ionization by intense ultraviolet emission from the sparks produced during the early times of its creation and/or heating by strong shocks generated by the kernel during its expansion into the ambient. In this study, an investigation is made on the spectral features of on- and off-axis emission features of laser-induced plasma breakdown kernels generated in atmospheric pressure conditions with an aim to elucidate the mechanisms leading to ambient excitation and emission. Pulses from an Nd:YAG laser emitting at 1064 nm with 6 ns pulse duration are used to generate plasma kernels. Laser sparks were generated in air, argon, and helium gases to provide different physical properties of expansion dynamics and plasma chemistry considering the differences in laser absorption properties, mass density and speciation. Point shadowgraphy and time-resolved imaging were used to evaluate the shock wave and spark self-emission morphology at early and late times while space and time resolved spectroscopy is used for evaluating the emission features as well as for inferring plasma fundaments at on- and off-axis. Structure and dynamics of the plasma kernel obtained using imaging techniques are also compared to numerical simulations using computational fluid dynamics code. The emission from the kernel showed that spectral features from ions, atoms and molecules are separated in

  7. Observation of spectral composition and polarization of sub-terahertz emission from dense plasma during relativistic electron beam–plasma interaction

    Energy Technology Data Exchange (ETDEWEB)

    Arzhannikov, A. V.; Burmasov, V. S.; Ivanov, I. A.; Kuznetsov, S. A.; Postupaev, V. V.; Sinitsky, S. L.; Vyacheslavov, L. N. [Budker Institute of Nuclear Physics, 11 Lavrentiev Ave., Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2 Pirogova St., Novosibirsk 630090 (Russian Federation); Burdakov, A. V. [Budker Institute of Nuclear Physics, 11 Lavrentiev Ave., Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20 Karl Marks Ave., Novosibirsk 630092 (Russian Federation); Gavrilenko, D. E.; Kasatov, A. A.; Mekler, K. I.; Rovenskikh, A. F. [Budker Institute of Nuclear Physics, 11 Lavrentiev Ave., Novosibirsk 630090 (Russian Federation); Polosatkin, S. V.; Sklyarov, V. F. [Budker Institute of Nuclear Physics, 11 Lavrentiev Ave., Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2 Pirogova St., Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20 Karl Marks Ave., Novosibirsk 630092 (Russian Federation)

    2014-08-15

    The paper presents results of measurements of sub-terahertz electromagnetic emission from magnetized plasma during injection of a powerful relativistic electron beam of microsecond duration in plasma with the density of 3 × 10{sup 14 }cm{sup −3}. It was found that the spectrum of the radiation concentrated in three distinct regions with high level of spectral power density. The first region is located near f{sub 1} = 100 GHz; the second one is in the vicinity of 190 GHz, and the third region is in the frequency interval f{sub 3} = 280–340 GHz. Polarization vectors of the emission in the first and third regions (f{sub 1} and f{sub 3}) are directed mainly perpendicular to the magnetic field in the plasma. At the same time, the polarization of the radiation in the vicinity of f{sub 2} = 190 GHz is parallel to the magnetic field. The most likely mechanism of electromagnetic wave generation in the frequency regions f{sub 1} and f{sub 2} is the linear conversion of the plasma oscillations into the electromagnetic waves on strong gradients of the plasma density. The third region is situated in the vicinity of second harmonic of electron plasma frequency, and we explain this emission by the coalescence of the upper-hybrid oscillations at high level turbulence in plasma.

  8. Interaction of High Intensity Electromagnetic Waves with Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    G. Shvets

    2008-10-03

    The focus of our work during the duration of this grant was on the following areas: (a) the fundamental plasma physics of intense laser-plasma interactions, including the nonlinear excitation of plasma waves for accelerator applications, as well as the recently discovered by us phenomenon of the relativistic bi-stability of relativistic plasma waves driven by a laser beatwave; (b) interaction of high power microwave beams with magnetized plasma, including some of the recently discovered by us phenomena such as the Undulator Induced Transparency (UIT) as well as the new approaches to dynamic manipulation of microwave pulses; (c) investigations of the multi-color laser pulse interactions in the plasma, including the recently discovered by us phenomenon of Electromagnetic Cascading (EC) and the effect of the EC of three-dimensional dynamics of laser pulses (enhanced/suppressed selffocusing etc.); (d) interaction of high-current electron beams with the ambient plasma in the context of Fast Ignitor (FI) physics, with the emphasis on the nonlinear dynamics of the Weibel instability and beam filamentation.

  9. Exotic x-ray emission from dense plasmas

    Science.gov (United States)

    Rosmej, F. B.; Dachicourt, R.; Deschaud, B.; Khaghani, D.; Dozières, M.; Šmíd, M.; Renner, O.

    2015-11-01

    Exotic x-ray emission from dense matter is identified as the complex high intensity satellite emission from autoionizing states of highly charged ions. Among a vast amount of possible transitions, double K-hole hollow ion (HI) x-ray emission K0L X → K1L X-1 + hν hollow is of exceptional interest due to its advanced diagnostic potential for matter under extreme conditions where opacity and radiation fields play important roles. Transient ab initio simulations identify intense short pulse radiation fields (e.g., those emitted by x-ray free electron lasers) as possible driving mechanisms of HI x-ray emission via two distinct channels: first, successive photoionization of K-shell electrons, second, photoionization followed by resonant photoexciation among various ionic charge states that are simultaneously present in high density matter. We demonstrated that charge exchange of intermixing inhomogenous plasmas as well as collisions driven by suprathermal electrons are possible mechanisms to populate HIs to observable levels in dense plasmas, particularly in high current Z-pinch plasmas and high intensity field-ionized laser produced plasmas. Although the HI x-ray transitions were repeatedly identified in many other cases of dense optical laser produced plasmas on the basis of atomic structure calculations, their origin is far from being understood and remains one of the last holy grails of high intensity laser-matter interaction.

  10. Uranium plasma emission coefficient in the visible and near UV.

    Science.gov (United States)

    Mack, J. M., Jr.; Usher, J. L.; Schneider, R. T.; Campbell, H. D.

    1971-01-01

    Measurements of the specific emission coefficient in the near ultra-violet and visible region of a uranium arc plasma are reported. Spatial unfolding of the intensity profile is used to determine the emission coefficient in the spectral range of 2000 A to 6000 A. The uranium partial pressure is estimated to range between .001 and .01 atmosphere, and the corresponding temperature range is 5000 - 10,000 K.

  11. Uranium plasma emission coefficient in the visible and near UV.

    Science.gov (United States)

    Mack, J. M., Jr.; Usher, J. L.; Schneider, R. T.; Campbell, H. D.

    1971-01-01

    Measurements of the specific emission coefficient in the near ultra-violet and visible region of a uranium arc plasma are reported. Spatial unfolding of the intensity profile is used to determine the emission coefficient in the spectral range of 2000 A to 6000 A. The uranium partial pressure is estimated to range between .001 and .01 atmosphere, and the corresponding temperature range is 5000 - 10,000 K.

  12. Magneto-Hydro-Dynamic Waves In The Collisionless Space Plasma

    Science.gov (United States)

    Dzhalilov, N. S.; Kuznetsov, V. D.; Staude, J.

    2007-12-01

    The instability of magneto-hydro-dynamic (MHD) waves in an anisotropic, collisionless, rarefied hot plasma is studied. Anisotropy properties of such a plasma are caused by a strong magnetic field, when the thermal gas pressures across and along the field become unequal. Moreover, there appears an anisotropy of the thermal fluxes. The study of the anisotropy features of the plasma are motivated by observed solar coronal data. The 16 moments equations derived from the Boltzmann-Vlasov kinetic equation are used. These equations strongly differ from the usual isotropic MHD case. For linear disturbances the wave equations in homogenous anisotropic plasma are deduced. The general dispersion relation for the incompressible wave modes is derived, solved and analyzed. It is shown that a wide wave spectrum with stable and unstable behavior is possible, in contrast to the usual isotropic MHD case. The dependence of the instability on magnetic field, pressure anisotropy, and heat fluxes is investigated. The general instability condition is obtained. The results can be applied to the theory of solar and stellar coronal heating, to wind models and in other modeling, where the collisionless approximation is valid.

  13. Investigation of heavy ions diffusion under the influence of current-driven mechanism and compositional waves in plasma

    CERN Document Server

    Urpin, Vadim

    2016-01-01

    We consider diffusion caused by a combined influence of the Hall effect and electric currents, and argue that such diffusion forms chemical inhomogeneities in plasma. The considered mechanism can be responsible for the formation of element spots in laboratory and astrophysical plasmas. Such current-driven diffusion can be accompanied by the propagation of a particular type of waves which have not been considered earlier. In these waves, the impurity number density oscillare alone and their frequency is determined by the electric currents and sort of impurity ions. These compositional waves exist if the magnetic pressure in plasma is much greater than the gas pressure. Such waves lead to local variations of chemical composition and, hence, can manifest themselves by variations of the emission in spectral lines.

  14. Observation of quasi-periodic frequency sweeping in electron cyclotron emission of nonequilibrium mirror-confined plasma

    CERN Document Server

    Viktorov, M E; Mansfeld, D A; Golubev, S V

    2016-01-01

    Chirping frequency patterns have been observed in the electron cyclotron emission from strongly nonequilibrium plasma confined in a table-top mirror magnetic trap. Such patterns are typical for the formation of nonlinear phase space structures in a proximity of the wave-particle resonances of a kinetically unstable plasma, also known as the "holes and clumps" mechanism. Our data provides the first experimental evidence for acting of this mechanism in the electron cyclotron frequency domain.

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

    Science.gov (United States)

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

    2017-01-01

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

  16. Electrostatic solitary waves in dusty pair-ion plasmas

    CERN Document Server

    Misra, A P

    2013-01-01

    The propagation of electrostatic waves in an unmagnetized collisionless pair-ion plasma with immobile positively charged dusts is studied for both large- and small-amplitude perturbations. Using a two-fluid model for pair-ions, it is shown that there appear two linear ion modes, namely the "fast" and "slow" waves in dusty pair-ion plasmas. The properties of these wave modes are studied with different mass $(m)$ and temperature $(T)$ ratios of negative to positive ions, as well as the effects of immobile charged dusts $(\\delta)$. For large-amplitude waves, the pseudopotential approach is performed, whereas the standard reductive perturbation technique (RPT) is used to study the small-amplitude Korteweg-de Vries (KdV) solitons. The profiles of the pseudopotential, the large amplitude solitons as well as the dynamical evolution of KdV solitons are numerically studied with the system parameters as above. It is found that the pair-ion plasmas with positively charged dusts support the propagation of solitary waves ...

  17. Surface Wave Propagation in non--ideal plasmas

    CERN Document Server

    Pandey, B P

    2015-01-01

    The properties of surface waves in a partially ionized, compressible magnetized plasma slab are investigated in this work. The waves are affected by the nonideal magnetohydrodynamic effects which causes finite drift of the magnetic field in the medium. When the magnetic field drift is ignored, the characteristics of the wave propagation in a partially ionized plasma fluid is similar to the fully ionized ideal MHD except now the propagation properties depend on the fractional ionization as well as on the compressibility of the medium. The phase velocity of the sausage and kink waves increases marginally (by a few percent) due to the compressibility of the medium in both ideal as well as Hall diffusion dominated regimes. However, unlike ideal regime, only waves below certain cut off frequency can propagate in the medium in Hall dominated regime. This cut off for a thin slab has a weak dependence on the plasma beta whereas for thick slab no such dependence exists. More importantly, since the cut off is introduce...

  18. Revisiting linear plasma waves for finite value of the plasma parameter

    Science.gov (United States)

    Grismayer, Thomas; Fahlen, Jay; Decyk, Viktor; Mori, Warren

    2010-11-01

    We investigate through theory and PIC simulations the Landau-damping of plasma waves with finite plasma parameter. We concentrate on the linear regime, γφB, where the waves are typically small and below the thermal noise. We simulate these condition using 1,2,3D electrostatic PIC codes (BEPS), noting that modern computers now allow us to simulate cases where (nλD^3 = [1e2;1e6]). We study these waves by using a subtraction technique in which two simulations are carried out. In the first, a small wave is initialized or driven, in the second no wave is excited. The results are subtracted to provide a clean signal that can be studied. As nλD^3 is decreased, the number of resonant electrons can be small for linear waves. We show how the damping changes as a result of having few resonant particles. We also find that for small nλD^3 fluctuations can cause the electrons to undergo collisions that eventually destroy the initial wave. A quantity of interest is the the life time of a particular mode which depends on the plasma parameter and the wave number. The life time is estimated and then compared with the numerical results. A surprising result is that even for large values of nλD^3 some non-Vlasov discreteness effects appear to be important.

  19. A Schamel equation for ion acoustic waves in superthermal plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Williams, G., E-mail: gwilliams06@qub.ac.uk; Kourakis, I. [Centre for Plasma Physics, Department of Physics and Astronomy, Queen' s University Belfast, BT7 1NN, Northern Ireland (United Kingdom); Verheest, F. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B-9000 Gent (Belgium); School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Hellberg, M. A. [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Anowar, M. G. M. [Department of Physics, Begum Rokeya University, Rangpur, Rangpur-5400 (Bangladesh)

    2014-09-15

    An investigation of the propagation of ion acoustic waves in nonthermal plasmas in the presence of trapped electrons has been undertaken. This has been motivated by space and laboratory plasma observations of plasmas containing energetic particles, resulting in long-tailed distributions, in combination with trapped particles, whereby some of the plasma particles are confined to a finite region of phase space. An unmagnetized collisionless electron-ion plasma is considered, featuring a non-Maxwellian-trapped electron distribution, which is modelled by a kappa distribution function combined with a Schamel distribution. The effect of particle trapping has been considered, resulting in an expression for the electron density. Reductive perturbation theory has been used to construct a KdV-like Schamel equation, and examine its behaviour. The relevant configurational parameters in our study include the superthermality index κ and the characteristic trapping parameter β. A pulse-shaped family of solutions is proposed, also depending on the weak soliton speed increment u{sub 0}. The main modification due to an increase in particle trapping is an increase in the amplitude of solitary waves, yet leaving their spatial width practically unaffected. With enhanced superthermality, there is a decrease in both amplitude and width of solitary waves, for any given values of the trapping parameter and of the incremental soliton speed. Only positive polarity excitations were observed in our parametric investigation.

  20. A microwave emissivity model of sea surface under wave breaking

    Institute of Scientific and Technical Information of China (English)

    Wei En-Bo; Ge Yong

    2005-01-01

    With the effective medium approximation theory of composites, a remedial model is proposed for estimating the microwave emissivity of sea surface under wave breaking driven by strong wind on the basis of an empirical model given by Pandey and Kakar. In our model, the effects of the shapes of seawater droplets and the thickness of whitecap layer (i.e. a composite layer of air and sea water droplets) over the sea surface on the microwave emissivity are investigated by calculating the effective dielectric constant of whitecaps layer. The wind speed is included in our model, and the responses of water droplets shapes, such as sphere and ellipsoid, to the emissivity are also discussed at different microwave frequencies. The model is in good agreement with the experimental data of microwave emissivity of sea surface at microwave frequencies of 6.6, 10.7 and 37GHz.

  1. Nonextensive dust acoustic waves in a charge varying dusty plasma

    Science.gov (United States)

    Bacha, Mustapha; Tribeche, Mouloud

    2012-01-01

    Our recent analysis on nonlinear nonextensive dust-acoustic waves (DA) [Amour and Tribeche in Phys. Plasmas 17:063702, 2010] is extended to include self-consistent nonadiabatic grain charge fluctuation. The appropriate nonextensive electron charging current is rederived based on the orbit-limited motion theory. Our results reveal that the amplitude, strength and nature of the nonlinear DA waves (solitons and shocks) are extremely sensitive to the degree of ion nonextensivity. Stronger is the electron correlation, more important is the charge variation induced nonlinear wave damping. The anomalous dissipation effects may prevail over that dispersion as the electrons evolve far away from their Maxwellian equilibrium. Our investigation may be of wide relevance to astronomers and space scientists working on interstellar dusty plasmas where nonthermal distributions are turning out to be a very common and characteristic feature.

  2. Modulated envelope localized wavepackets associated with electrostatic plasma waves

    CERN Document Server

    Kourakis, I; Kourakis, Ioannis; Shukla, Padma Kant

    2004-01-01

    The nonlinear amplitude modulation of known electrostatic plasma modes is examined in a generic manner, by applying a collisionless fluid model. Both cold (zero-temperature) and warm fluid descriptions are discussed and the results are compared. The moderately nonlinear oscillation regime is investigated by applying a multiple scale technique. The calculation leads to a Nonlinear Schrodinger-type Equation (NLSE), which describes the evolution of the slowly varying wave amplitude in time and space. The NLSE admits localized envelope (solitary wave) solutions of bright- (pulses) or dark- (holes, voids) type, whose characteristics (maximum amplitude, width) depend on intrinsic plasma parameters. Effects like amplitude perturbation obliqueness, finite temperature and defect (dust) concetration are explicitly considered. The relevance with similar highly localized modulated wave structures observed during recent satellite missions is discussed.

  3. Solitary and freak waves in superthermal plasma with ion jet

    Science.gov (United States)

    Abdelsalam, U. M.; Abdelsalam

    2013-06-01

    The nonlinear solitary and freak waves in a plasma composed of positive and negative ions, superthermal electrons, ion beam, and stationary dust particles have been investigated. The reductive perturbation method is used to obtain the Korteweg-de Vries (KdV) equation describing the system. The latter admits solitary wave solution, while the dynamics of the modulationally unstable wavepackets described by the KdV equation gives rise to the formation of freak/rogue excitation described by the nonlinear Schrödinger equation. In order to show that the characteristics of solitary and freak waves are influenced by plasma parameters, relevant numerical analysis of appropriate nonlinear solutions are presented. The results from this work predict nonlinear excitations that may associate with ion jet and superthermal electrons in Herbig-Haro objects.

  4. Generation of Diffuse Large Volume Plasma by an Ionization Wave from a Plasma Jet

    Science.gov (United States)

    Laroussi, Mounir; Razavi, Hamid

    2015-09-01

    Low temperature plasma jets emitted in ambient air are the product of fast ionization waves that are guided within a channel of a gas flow, such as helium. This guided ionization wave can be transmitted through a dielectric material and under some conditions can ignite a discharge behind the dielectric material. Here we present a novel way to produce large volume diffuse low pressure plasma inside a Pyrex chamber that does not have any electrodes or electrical energy directly applied to it. The diffuse plasma is ignited inside the chamber by a plasma jet located externally to the chamber and that is physically and electrically unconnected to the chamber. Instead, the plasma jet is just brought in close proximity to the external wall/surface of the chamber or to a dielectric tubing connected to the chamber. The plasma thus generated is diffuse, large volume and with physical and chemical characteristics that are different than the external plasma jet that ignited it. So by using a plasma jet we are able to ``remotely'' ignite volumetric plasma under controlled conditions. This novel method of ``remote'' generation of a low pressure, low temperature diffuse plasma can be useful for various applications including material processing and biomedicine.

  5. Coherent structures and transport in drift wave plasma turbulence

    DEFF Research Database (Denmark)

    Korsholm, Søren Bang

    for optimization. The present work is a part of the puzzle to understand the basic physics of transport induced by drift wave turbulence in the edge region of a plasma. The basis for the study is the Hasegawa- Wakatani model. Simulation results for 3D periodic and nonperiodic geometries are presented. The Hasegawa......-Wakatani model is further expanded to include ion temperature effects. Another expansion of the model is derived from the Braginskii electron temperature equation. The result is a self-consistent set of equations describing the dynamical evolution of the drift wave fluctuations of the electron density, electron......Fusion energy research aims at developing fusion power plants providing safe and clean energy with abundant fuels. Plasma turbulence induced transport of energy and particles is a performance limiting factor for fusion devices. Hence the understanding of plasma turbulence is important...

  6. Search for an emission line of a gravitational wave background

    CERN Document Server

    Nishizawa, Atsushi

    2015-01-01

    In the light of the history of researches on electromagnetic wave spectrum, a sharp emission line of gravitational-wave background (GWB) would be an interesting observational target. Here we study an efficient method to detect a line GWB by correlating data of multiple ground-based detectors. We find that the width of frequency bin for coarse graining is a critical parameter, and the commonly-used value 0.25 Hz is far from optimal, decreasing the signal-to-noise ratio by up to a factor of seven. By reanalyzing the existing data with a smaller bin width, we might detect a precious line signal from the early universe.

  7. Helicon waves in uniform plasmas. II. High m numbers

    Energy Technology Data Exchange (ETDEWEB)

    Stenzel, R. L.; Urrutia, J. M. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)

    2015-09-15

    Helicons are whistler modes with azimuthal wave numbers. They have been studied in solids and plasmas where boundaries play a role. The present work shows that very similar modes exist in unbounded gaseous plasmas. Instead of boundaries, the antenna properties determine the topology of the wave packets. The simplest antenna is a magnetic loop which excites m = 0 or m = 1 helicons depending on whether the dipole moment is aligned parallel or perpendicular to the ambient background magnetic field B{sub 0}. While these low order helicons have been described by J. M. Urrutia and R. L. Stenzel [“Helicon modes in uniform plasmas. I. Low m modes,” Phys. Plasmas 22, 092111 (2015)], the present work focuses on high order modes up to m = 8. These are excited by antenna arrays forming magnetic multipoles. Their wave magnetic field has been measured in space and time in a large and uniform laboratory plasma free of boundary effects. The observed wave topology exhibits m pairs of unique field line spirals which may have inspired the name “helicon” to this mode. All field lines converge into these nested spirals which propagate like corkscrews along B{sub 0}. The field lines near the axis of helicons are perpendicular to B{sub 0} and circularly polarized as in parallel whistlers. Helical antennas couple to these transverse fields but not to the spiral fields of helicons. Using a circular antenna array of phased m = 0 loops, right or left rotating or non-rotating multipole antenna fields are generated. They excite m < 0 and m > 0 modes, showing that the plasma supports both modes equally well. The poor excitation of m < 0 modes is a characteristic of loops with dipole moment across B{sub 0}. The radiation efficiency of multipole antennas has been found to decrease with m.

  8. Bernstein wave aided laser third harmonic generation in a plasma

    Science.gov (United States)

    Tyagi, Yachna; Tripathi, Deepak; Kumar, Ashok

    2016-09-01

    The process of Bernstein wave aided resonant third harmonic generation of laser in a magnetized plasma is investigated. The extra-ordinary mode (X-mode) laser of frequency ω 0 and wave number k → 0 , travelling across the magnetic field in a plasma, exerts a second harmonic ponderomotive force on the electrons imparting them an oscillatory velocity v → 2 ω0 , 2 k → 0 . This velocity beats with the density perturbation due to the Bernstein wave to produce a density perturbation at cyclotron frequency shifted second harmonic. The density perturbation couples with the oscillatory velocity v → ω0 , k → 0 of X-mode of the laser to produce the cyclotron frequency shifted third harmonic current density leading to harmonic radiation. The phase matching condition for the up shifted frequency is satisfied when the Bernstein wave is nearly counter-propagating to the laser. As the transverse wave number of the Bernstein wave is large, it is effective in the phase matched third harmonic generation, when the laser frequency is not too far from the upper hybrid frequency.

  9. Nonlinear Alfvén wave dynamics in plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Anwesa; Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Schamel, Hans [Theoretical Physics, University of Bayreuth, D-95440 Bayreuth (Germany)

    2015-07-15

    Nonlinear Alfvén wave dynamics is presented using Lagrangian fluid approach in a compressible collisional magnetized plasma. In the framework of two fluid dynamics, finite electron inertia is shown to serve as a dispersive effect acting against the convective nonlinearity. In a moving frame, the Alfvén wave can, therefore, form an arbitrarily strong amplitude solitary wave structure due to the balance between nonlinearity and dispersion. Weak amplitude Alfvén waves are shown to be governed by a modified KdV equation, which extends for finite dissipation to a mKdV-Burgers equation. These equations have well known solutions. Next, we have analyzed the fourth order nonlinear Alfvén wave system of equations both numerically and by approximation method. The results indicate a collapse of the density and magnetic field irrespective of the presence of dispersion. The wave magnetic field, however, appears to be less singular showing collapse only when the dispersive effects are negligible. These results may contribute to our understanding of the generation of strongly localized magnetic fields (and currents) in plasmas and are expected to be of special importance in the astrophysical context of magnetic star formation.

  10. Nonlinear Alfvén wave dynamics in plasmas

    Science.gov (United States)

    Sarkar, Anwesa; Chakrabarti, Nikhil; Schamel, Hans

    2015-07-01

    Nonlinear Alfvén wave dynamics is presented using Lagrangian fluid approach in a compressible collisional magnetized plasma. In the framework of two fluid dynamics, finite electron inertia is shown to serve as a dispersive effect acting against the convective nonlinearity. In a moving frame, the Alfvén wave can, therefore, form an arbitrarily strong amplitude solitary wave structure due to the balance between nonlinearity and dispersion. Weak amplitude Alfvén waves are shown to be governed by a modified KdV equation, which extends for finite dissipation to a mKdV-Burgers equation. These equations have well known solutions. Next, we have analyzed the fourth order nonlinear Alfvén wave system of equations both numerically and by approximation method. The results indicate a collapse of the density and magnetic field irrespective of the presence of dispersion. The wave magnetic field, however, appears to be less singular showing collapse only when the dispersive effects are negligible. These results may contribute to our understanding of the generation of strongly localized magnetic fields (and currents) in plasmas and are expected to be of special importance in the astrophysical context of magnetic star formation.

  11. Potential role of kinetic Alfvén waves and whistler waves in solar wind plasmas

    Science.gov (United States)

    Nandal, P.; Yadav, N.; Sharma, R. P.; Goldstein, M. L.

    2016-07-01

    Spacecraft observations indicate the signatures of highly oblique kinetic Alfvén waves (KAWs) and whistler waves in the solar wind plasma. In the present work, we explore the possible role of KAWs and whistler waves in the observed solar wind magnetic turbulent spectrum. The nonlinear spatial evolution of KAW is studied including the effects of the ponderomotive force which results in intense localized structures due to the background density modification. Weak quasi-transverse whistler wave propagating through these localized structures also gets localized in the form of small-scale localized structures. We present numerically calculated magnetic power spectra for both KAW as well as for whistler wave. Our obtained results demonstrate the important role that KAWs and whistler waves play in the energy cascading from larger to smaller scales. The relevance of these results to recent spacecraft observations is also pointed out.

  12. Radio Emissions from Plasma with Electron Kappa-Distributions

    Science.gov (United States)

    Fleishman, G. D.; Kuznetsov, A. A.

    2015-12-01

    Gregory Fleishman (New Jersey Institute of Technology, Newark, USA)Alexey Kuznetsov (Institute of Solar-Terrestrial Physics, Irkutsk, Russia), Currently there is a concern about the ability of the classical thermal (Maxwellian) distribution to describe quasisteady-state plasma in the solar atmosphere, including active regions. In particular, other distributions have been proposed to better fit observations, for example, kappa-distributions. If present, these distributions will generate radio emissions with different observable properties compared with the classical gyroresonance (GR) or free-free emission, which implies a way of remotely detecting these kappa distributions in the radio observations. Here we present analytically derived GR and free-free emissivities and absorption coefficients for the kappa-distribution, and discuss their properties, which are in fact remarkably different from the classical Maxwellian plasma. In particular, the radio brightness temperature from a gyrolayer increases with the optical depth τ for kappa-distribution. This property has a remarkable consequence allowing a straightforward observational test: the GR radio emission from the non-Maxwellian distributions is supposed to be noticeably polarized even in the optically thick case, where the emission would have strictly zero polarization in the case of Maxwellian plasma. This offers a way of remote probing the plasma distribution in astrophysical sources, including solar active regions as a vivid example. In this report, we present analytical formulae and computer codes to calculate the emission parameters. We simulate the gyroresonance emission under the conditions typical of the solar active regions and compare the results for different electron distributions. We discuss the implications of our findings for interpretation of radio observations. This work was supported in part by NSF grants AGS-1250374 and AGS-1262772, NASA grant NNX14AC87G to New Jersey Institute of Technology

  13. Obliquely propagating large amplitude solitary waves in charge neutral plasmas

    Directory of Open Access Journals (Sweden)

    F. Verheest

    2007-01-01

    Full Text Available This paper deals in a consistent way with the implications, for the existence of large amplitude stationary structures in general plasmas, of assuming strict charge neutrality between electrons and ions. With the limit of pair plasmas in mind, electron inertia is retained. Combining in a fluid dynamic treatment the conservation of mass, momentum and energy with strict charge neutrality has indicated that nonlinear solitary waves (as e.g. oscillitons cannot exist in electron-ion plasmas, at no angle of propagation with respect to the static magnetic field. Specifically for oblique propagation, the proof has turned out to be more involved than for parallel or perpendicular modes. The only exception is pair plasmas that are able to support large charge neutral solitons, owing to the high degree of symmetry naturally inherent in such plasmas. The nonexistence, in particular, of oscillitons is attributed to the breakdown of the plasma approximation in dealing with Poisson's law, rather than to relativistic effects. It is hoped that future space observations will allow to discriminate between oscillitons and large wave packets, by focusing on the time variability (or not of the phase, since the amplitude or envelope graphs look very similar.

  14. Relativistic warm plasma theory of nonlinear laser-driven electron plasma waves.

    Science.gov (United States)

    Schroeder, C B; Esarey, E

    2010-05-01

    A relativistic, warm fluid model of a nonequilibrium, collisionless plasma is developed and applied to examine nonlinear Langmuir waves excited by relativistically intense, short-pulse lasers. Closure of the covariant fluid theory is obtained via an asymptotic expansion assuming a nonrelativistic plasma temperature. The momentum spread is calculated in the presence of an intense laser field and shown to be intrinsically anisotropic. Coupling between the transverse and longitudinal momentum variances is enabled by the laser field. A generalized dispersion relation is derived for Langmuir waves in a thermal plasma in the presence of an intense laser field. Including thermal fluctuations in three-velocity-space dimensions, the properties of the nonlinear electron plasma wave, such as the plasma temperature evolution and nonlinear wavelength, are examined and the maximum amplitude of the nonlinear oscillation is derived. The presence of a relativistically intense laser pulse is shown to strongly influence the maximum plasma wave amplitude for nonrelativistic phase velocities owing to the coupling between the longitudinal and transverse momentum variances.

  15. Loop heating by D.C. electric current and electromagnetic wave emissions simulated by 3-D EM particle zone

    Science.gov (United States)

    Sakai, J. I.; Zhao, J.; Nishikawa, K.-I.

    1994-01-01

    We have shown that a current-carrying plasma loop can be heated by magnetic pinch driven by the pressure imbalance between inside and outside the loop, using a 3-dimensional electromagnetic (EM) particle code. Both electrons and ions in the loop can be heated in the direction perpendicular to the ambient magnetic field, therefore the perpendicular temperature can be increased about 10 times compared with the parallel temperature. This temperature anisotropy produced by the magnetic pinch heating can induce a plasma instability, by which high-frequency electromagnetic waves can be excited. The plasma current which is enhanced by the magnetic pinch can also excite a kinetic kink instability, which can heat ions perpendicular to the magnetic field. The heating mechanism of ions as well as the electromagnetic emission could be important for an understanding of the coronal loop heating and the electromagnetic wave emissions from active coronal regions.

  16. Emission of radiation induced by pervading Alfven waves

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, G. Q. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wu, C. S. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing (China); Institute of Space Science, National Central University, Zhongli, Taiwan (China)

    2013-03-15

    It is shown that under certain conditions, propagating Alfven waves can energize electrons so that consequently a new cyclotron maser instability is born. The necessary condition is that the plasma frequency is lower than electron gyrofrequency. This condition implies high Alfven speed, which can pitch-angle scatter electrons effectively and therefore the electrons are able to acquire free energy which are needed for the instability.

  17. Oblique solitary waves in a five component plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sijo, S.; Manesh, M.; Sreekala, G.; Venugopal, C., E-mail: cvgmgphys@yahoo.co.in [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, 686 560 Kerala (India); Neethu, T. W. [Department of Physics, CMS College, Mahatma Gandhi University, Kottayam, 686 001 Kerala (India); Renuka, G. [Kerala State Council for Science, Technology and Environment, Thiruvananthapuram, 695 004 Kerala (India)

    2015-12-15

    We investigate the influence of a second electron component on oblique dust ion acoustic solitary waves in a five component plasma consisting of positively and negatively charged dust, hydrogen ions, and hotter and colder electrons. Of these, the heavier dust and colder photo-electrons are of cometary origin while the other two are of solar origin; electron components are described by kappa distributions. The K-dV equation is derived, and different attributes of the soliton such as amplitude and width are plotted for parameters relevant to comet Halley. We find that the second electron component has a profound influence on the solitary wave, decreasing both its amplitude and width. The normalized hydrogen density strongly influences the solitary wave by decreasing its width; the amplitude of the solitary wave, however, increases with increasing solar electron temperatures.

  18. Electromagnetic ion cyclotron waves observed in the plasma depletion layer

    Science.gov (United States)

    Anderson, B. J.; Fuselier, S. A.; Murr, D.

    1991-01-01

    Observations from AMPTE/CCE in the earth's magnetosheath on October 5, 1984 are presented to illustrate 0.1 - 4.0 Hz magnetic field pulsations in the subsolar plasma depletion layer (PDL) for northward sheath field during a magnetospheric compression. The PDL is unambiguously identified by comparing CCE data with data from IRM in the upstream solar wind. Pulsations in the PDL are dominated by transverse waves with F/F(H+) 1.0 or less and a slot in spectral power at F/F(H+) = 0.5. The upper branch is left hand polarized while the lower branch is linearly polarized. In the sheath the proton temperature anisotropy is about 0.6 but it is about 1.7 in the PDL during wave occurrence. The properties and correlation of waves with increased anisotropy indicate that they are electromagnetic ion cyclotron waves.

  19. Quantum ion-acoustic solitary waves in weak relativistic plasma

    Indian Academy of Sciences (India)

    Biswajit Sahu

    2011-06-01

    Small amplitude quantum ion-acoustic solitary waves are studied in an unmagnetized twospecies relativistic quantum plasma system, comprised of electrons and ions. The one-dimensional quantum hydrodynamic model (QHD) is used to obtain a deformed Korteweg–de Vries (dKdV) equation by reductive perturbation method. A linear dispersion relation is also obtained taking into account the relativistic effect. The properties of quantum ion-acoustic solitary waves, obtained from the deformed KdV equation, are studied taking into account the quantum mechanical effects in the weak relativistic limit. It is found that relativistic effects significantly modify the properties of quantum ion-acoustic waves. Also the effect of the quantum parameter on the nature of solitary wave solutions is studied in some detail.

  20. Full wave simulation of waves in ECRIS plasmas based on the finite element method

    Energy Technology Data Exchange (ETDEWEB)

    Torrisi, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania, Italy and Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Via Graziella, I (Italy); Mascali, D.; Neri, L.; Castro, G.; Patti, G.; Celona, L.; Gammino, S.; Ciavola, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania (Italy); Di Donato, L. [Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica (DIEEI), Viale Andrea Doria 6, 95125 Catania (Italy); Sorbello, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, 95123, Catania, Italy and Università degli Studi di Catania, Dipartimento di Ingegneria Elettrica Elettronica ed Informatica (DIEEI), Viale Andrea Doria 6, 95125 Catania (Italy); Isernia, T. [Università Mediterranea di Reggio Calabria, Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Via Graziella, I-89100 Reggio Calabria (Italy)

    2014-02-12

    This paper describes the modeling and the full wave numerical simulation of electromagnetic waves propagation and absorption in an anisotropic magnetized plasma filling the resonant cavity of an electron cyclotron resonance ion source (ECRIS). The model assumes inhomogeneous, dispersive and tensorial constitutive relations. Maxwell's equations are solved by the finite element method (FEM), using the COMSOL Multiphysics{sup ®} suite. All the relevant details have been considered in the model, including the non uniform external magnetostatic field used for plasma confinement, the local electron density profile resulting in the full-3D non uniform magnetized plasma complex dielectric tensor. The more accurate plasma simulations clearly show the importance of cavity effect on wave propagation and the effects of a resonant surface. These studies are the pillars for an improved ECRIS plasma modeling, that is mandatory to optimize the ion source output (beam intensity distribution and charge state, especially). Any new project concerning the advanced ECRIS design will take benefit by an adequate modeling of self-consistent wave absorption simulations.

  1. Transfer Matrix for Obliquely Incident Electromagnetic Waves Propagating in One Dimension Plasma Photonic Crystals

    Institute of Scientific and Technical Information of China (English)

    GUO Bin

    2009-01-01

    Based on the electromagnetic theory and by using an analytical technique-the transfer matrix method,the obliquely incident electromagnetic waves propagating in one-dimension plasma photonic crystals is studied.The dispersion relations for both the P-polarization waves and S-polarization waves,depending on the plasma density,plasma thickness and period,are discussed.

  2. Incoherent synchrotron emission of laser-driven plasma edge

    CERN Document Server

    Serebryakov, D A; Kostyukov, I Yu

    2015-01-01

    When a relativistically intense linearly polarized laser pulse is incident on an overdense plasma, a dense electron layer is formed on the plasma edge which relativistic motion results in high harmonic generation, ion acceleration and incoherent synchrotron emission of gamma-photons. Here we present a self-consistent analytical model that describes the edge motion and apply it to the problem of incoherent synchrotron emission by ultrarelativistic plasma electrons. The model takes into account both coherent radiation reaction from high harmonics and incoherent radiation reaction in the Landau-Lifshitz form. The analytical results are in agreement with 3D particle-in-cell simulations in a certain parameter region that corresponds to the relativistic electronic spring interaction regime.

  3. Incoherent synchrotron emission of laser-driven plasma edge

    Energy Technology Data Exchange (ETDEWEB)

    Serebryakov, D. A., E-mail: dmserebr@gmail.com; Nerush, E. N.; Kostyukov, I. Yu. [Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Nizhny Novgorod State University, 23 Gagarin Avenue, Nizhny Novgorod 603950 (Russian Federation)

    2015-12-15

    When a relativistically intense linearly polarized laser pulse is incident on an overdense plasma, a dense electron layer is formed on the plasma edge which relativistic motion results in high harmonic generation, ion acceleration, and incoherent synchrotron emission of gamma-photons. Here we present a self-consistent analytical model that describes the edge motion and apply it to the problem of incoherent synchrotron emission by ultrarelativistic plasma electrons. The model takes into account both coherent radiation reaction from high harmonics and incoherent radiation reaction in the Landau–Lifshitz form. The analytical results are in agreement with 3D particle-in-cell simulations in a certain parameter region that corresponds to the relativistic electronic spring interaction regime.

  4. Incoherent synchrotron emission of laser-driven plasma edge

    Science.gov (United States)

    Serebryakov, D. A.; Nerush, E. N.; Kostyukov, I. Yu.

    2015-12-01

    When a relativistically intense linearly polarized laser pulse is incident on an overdense plasma, a dense electron layer is formed on the plasma edge which relativistic motion results in high harmonic generation, ion acceleration, and incoherent synchrotron emission of gamma-photons. Here we present a self-consistent analytical model that describes the edge motion and apply it to the problem of incoherent synchrotron emission by ultrarelativistic plasma electrons. The model takes into account both coherent radiation reaction from high harmonics and incoherent radiation reaction in the Landau-Lifshitz form. The analytical results are in agreement with 3D particle-in-cell simulations in a certain parameter region that corresponds to the relativistic electronic spring interaction regime.

  5. Investigation of the Millimeter-Wave Plasma Assisted CVD Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Vikharev, A; Gorbachev, A; Kozlov, A; Litvak, A; Bykov, Y; Caplan, M

    2005-07-21

    A polycrystalline diamond grown by the chemical vapor deposition (CVD) technique is recognized as a unique material for high power electronic devices owing to unrivaled combination of properties such as ultra-low microwave absorption, high thermal conductivity, high mechanical strength and chemical stability. Microwave vacuum windows for modern high power sources and transmission lines operating at the megawatt power level require high quality diamond disks with a diameter of several centimeters and a thickness of a few millimeters. The microwave plasma-assisted CVD technique exploited today to produce such disks has low deposition rate, which limits the availability of large size diamond disk windows. High-electron-density plasma generated by the millimeter-wave power was suggested for enhanced-growth-rate CVD. In this paper a general description of the 30 GHz gyrotron-based facility is presented. The output radiation of the gyrotron is converted into four wave-beams. Free localized plasma in the shape of a disk with diameter much larger than the wavelength of the radiation is formed in the intersection area of the wave-beams. The results of investigation of the plasma parameters, as well as the first results of diamond film deposition are presented. The prospects for commercially producing vacuum window diamond disks for high power microwave devices at much lower costs and processing times than currently available are outlined.

  6. Excitation and evolution of finite-amplitude plasma wave

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Y. W.; Wu, Y. C., E-mail: yican.wu@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Chen, M. X. [School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei, Anhui 230009 (China); Yu, M. Y., E-mail: myyu@zju.edu.cn [Institute for Fusion Theory and Simulation and Department of Physics, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, D-44780 Bochum (Germany); Wu, B. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2015-12-15

    The evolution of a small spatially periodic perturbation in the electron velocity distribution function in collisionless plasma is reconsidered by numerically solving the Vlasov and Poisson equations. The short as well as long time behaviors of the excited oscillations and damping/modulation are followed. In the small but finite-amplitude excited plasma wave, resonant electrons become trapped in the wave potential wells and their motion affects the low-velocity electrons participating in the plasma oscillations, leading to modulation of the latter at an effective trapping frequency. It is found that the phase space of the resonant and low-velocity electrons becomes chaotic, but then self-organization takes place but remains fine-scale chaotic. It is also found that as long as particles are trapped, there is only modulation and no monotonic damping of the excited plasma wave. The modulation period/amplitude increases/decreases as the magnitude of the initial disturbance is reduced. For the initial and boundary conditions used here, linear Landau damping corresponds to the asymptotic limit of the modulation period becoming infinite, or no trapping of the resonant electrons.

  7. Dust Acoustic Wave Excitation in a Plasma with Warm Dust

    Science.gov (United States)

    Rosenberg, M.; Thomas, E., Jr.; Marcus, L.; Fisher, R.; Williams, J. D.; Merlino, R. L.

    2008-11-01

    Measurements of the dust acoustic wave dispersion relation in dusty plasmas formed in glow discharges at the University of Iowa [1] and Auburn University [2] have shown the importance of finite dust temperature effects. The effect of dust grains with large thermal speeds was taken into account using kinetic theory of the ion-dust streaming instability [3]. The results of analytic and numerical calculations of the dispersion relation based on the kinetic theory will be presented and compared with the experimental results. [1] E. Thomas, Jr., R. Fisher, and R. L. Merlino, Phys. Plasmas 14, 123701 (2007). [2] J. D. Williams, E. Thomas Jr., and L. Marcus, Phys. Plasmas 15, 043704 (2008). [3] M. Rosenberg, E. Thomas Jr., and R. L. Merlino, Phys. Plasmas 15, 073701 (2008).

  8. Effects of magnetic field on the interaction between terahertz wave and non-uniform plasma slab

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Yuan; Han, YiPing; Guo, LiXin [School of physics and optoelectronic engineering, Xidian University, Xi' an 710071 (China); Ai, Xia [National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematical, Beijing 100076 (China)

    2015-10-15

    In this paper, the interaction between terahertz electromagnetic wave and a non-uniform magnetized plasma slab is investigated. Different from most of the published literatures, the plasma employed in this work is inhomogeneous in both collision frequency and electron density. Profiles are introduced to describe the non-uniformity of the plasma slab. At the same time, magnetic field is applied to the background of the plasma slab. It came out with an interesting phenomenon that there would be a valley in the absorption band as the plasma's electromagnetic characteristic is affected by the magnetic field. In addition, the valley located just near the middle of the absorption peak. The cause of the valley's appearance is inferred in this paper. And the influences of the variables, such as magnetic field strength, electron density, and collision frequency, are discussed in detail. The objective of this work is also pointed out, such as the applications in flight communication, stealth, emissivity, plasma diagnose, and other areas of plasma.

  9. The incomplete plasma dispersion function: properties and application to waves in bounded plasmas

    CERN Document Server

    Baalrud, Scott D

    2013-01-01

    The incomplete plasma dispersion function is a generalization of the plasma dispersion function in which the defining integral spans a semi-infinite, rather than infinite, domain. It is useful for describing the linear dielectric response and wave dispersion in non-Maxwellian plasmas when the distribution functions can be approximated as Maxwellian over finite, or semi-infinite, intervals in velocity phase-space. A ubiquitous example is the depleted Maxwellian electron distribution found near boundary sheaths or double layers, where the passing interval can be modeled as Maxwellian with a lower temperature than the trapped interval. The depleted Maxwellian is used as an example to demonstrate the utility of using the incomplete plasma dispersion function for calculating modifications to wave dispersion relations.

  10. Probing electron acceleration and X-ray emission in laser-plasma accelerator

    CERN Document Server

    Thaury, C; Corde, S; Brijesh, P; Lambert, G; Mangles, S P D; Bloom, M S; Kneip, S; Malka, V

    2013-01-01

    While laser-plasma accelerators have demonstrated a strong potential in the acceleration of electrons up to giga-electronvolt energies, few experimental tools for studying the acceleration physics have been developed. In this paper, we demonstrate a method for probing the acceleration process. A second laser beam, propagating perpendicular to the main beam is focused in the gas jet few nanosecond before the main beam creates the accelerating plasma wave. This second beam is intense enough to ionize the gas and form a density depletion which will locally inhibit the acceleration. The position of the density depletion is scanned along the interaction length to probe the electron injection and acceleration, and the betatron X-ray emission. To illustrate the potential of the method, the variation of the injection position with the plasma density is studied.

  11. Spectroscopic measurements of plasma emission light for plasma-based acceleration experiments

    Science.gov (United States)

    Filippi, F.; Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Zigler, A.

    2016-09-01

    Advanced particle accelerators are based on the excitation of large amplitude plasma waves driven by either electron or laser beams. Future experiments scheduled at the SPARC_LAB test facility aim to demonstrate the acceleration of high brightness electron beams through the so-called resonant Plasma Wakefield Acceleration scheme in which a train of electron bunches (drivers) resonantly excites wakefields into a preformed hydrogen plasma; the last bunch (witness) injected at the proper accelerating phase gains energy from the wake. The quality of the accelerated beam depends strongly on plasma density and its distribution along the acceleration length. The measurements of plasma density of the order of 1016-1017 cm-3 can be performed with spectroscopic measurements of the plasma-emitted light. The measured density distribution for hydrogen filled capillary discharge with both Balmer alpha and Balmer beta lines and shot-to-shot variation are here reported.

  12. The Nonlinear Landau Damping Rate of a Driven Plasma Wave

    Energy Technology Data Exchange (ETDEWEB)

    Benisti, D; Strozzi, D J; Gremillet, L; Morice, O

    2009-08-04

    In this Letter, we discuss the concept of the nonlinear Landau damping rate, {nu}, of a driven electron plasma wave, and provide a very simple, practical, analytic formula for {nu} which agrees very well with results inferred from Vlasov simulations of stimulated Raman scattering. {nu} actually is more complicated an operator than a plain damping rate, and it may only be seen as such because it assumes almost constant values before abruptly dropping to 0. The decrease of {nu} to 0 is moreover shown to occur later when the wave amplitude varies in the direction transverse to its propagation.

  13. Wave propagation in a moving cold magnetized plasma

    Science.gov (United States)

    Hebenstreit, H.

    1980-03-01

    Polarization relations and dispersion equations are derived for media that are electrically anisotropic in the comoving frame. Three-dimensional calculations for media at rest recover the known dispersion equations, i.e., Astrom's dispersion equation for magnetized cold plasmas and Fresnel's wave normal equation for uniaxial crystals. An analogous four-dimensional calculation yields the generalization to moving media. The dispersion equations so obtained for moving gyrotropic media are then discussed qualitatively for various special media and special directions of wave propagation. Finally, the polarization relations are specialized to media gyrotropic in the comoving frame.

  14. Ladder Climbing and Autoresonant Acceleration of Plasma Waves

    CERN Document Server

    Barth, Ido; Fisch, Nathaniel J

    2015-01-01

    Classical plasma waves are predicted to exhibit quantumlike ladder climbing, which is achieved by chirped modulations of the background density. An equivalence with the quantum particle in a box is identified and used to calculate the efficiency and the rate of this effect. In the limit of densely spaced spectrum, ladder climbing transforms into continuous autoresonance; plasmons may then be manipulated by chirped background modulations much like electrons are autoresonantly manipulated by chirped fields. Such ladder climbing and autoresonance effects are also predicted for other classical waves by means of a unifying Lagrangian theory.

  15. Multispacecraft analysis of dipolarization fronts and associated whistler wave emissions using MMS data

    Science.gov (United States)

    Breuillard, H.; Le Contel, O.; Retino, A.; Chasapis, A.; Chust, T.; Mirioni, L.; Graham, D. B.; Wilder, F. D.; Cohen, I.; Vaivads, A.; Khotyaintsev, Yu. V.; Lindqvist, P.-A.; Marklund, G. T.; Burch, J. L.; Torbert, R. B.; Ergun, R. E.; Goodrich, K. A.; Macri, J.; Needell, J.; Chutter, M.; Rau, D.; Dors, I.; Russell, C. T.; Magnes, W.; Strangeway, R. J.; Bromund, K. R.; Plaschke, F.; Fischer, D.; Leinweber, H. K.; Anderson, B. J.; Le, G.; Slavin, J. A.; Kepko, E. L.; Baumjohann, W.; Mauk, B.; Fuselier, S. A.; Nakamura, R.

    2016-07-01

    Dipolarization fronts (DFs), embedded in bursty bulk flows, play a crucial role in Earth's plasma sheet dynamics because the energy input from the solar wind is partly dissipated in their vicinity. This dissipation is in the form of strong low-frequency waves that can heat and accelerate energetic electrons up to the high-latitude plasma sheet. However, the dynamics of DF propagation and associated low-frequency waves in the magnetotail are still under debate due to instrumental limitations and spacecraft separation distances. In May 2015 the Magnetospheric Multiscale (MMS) mission was in a string-of-pearls configuration with an average intersatellite distance of 160 km, which allows us to study in detail the microphysics of DFs. Thus, in this letter we employ MMS data to investigate the properties of dipolarization fronts propagating earthward and associated whistler mode wave emissions. We show that the spatial dynamics of DFs are below the ion gyroradius scale in this region (˜500 km), which can modify the dynamics of ions in the vicinity of the DF (e.g., making their motion nonadiabatic). We also show that whistler wave dynamics have a temporal scale of the order of the ion gyroperiod (a few seconds), indicating that the perpendicular temperature anisotropy can vary on such time scales.

  16. Ion cyclotron emission calculations using a 2D full wave numerical code

    Energy Technology Data Exchange (ETDEWEB)

    Batchelor, D.B.; Jaeger, E.F.; Colestock, P.L.

    1987-01-01

    Measurement of radiation in the HF band due to cyclotron emission by energetic ions produced by fusion reactions or neutral beam injection promises to be a useful diagnostic on the large devices which are entering the reactor regime of operation. A number of complications make the modelling and interpretation of such measurements difficult using conventional geometrical optics methods. In particular, the long wavelength and lack of high directivity of antennas in this frequency regime make observation of a single path across the plasma into a viewing dump impractical. Pickup antennas effectively see the whole plasma and wall reflection effects are important. The 2D full wave ICHR code has been modified to calculate wave fields due to a distribution of energetic ions in tokamak geometry. The radiation is modeled as due to an ensemble of localized source currents distributed in space. The spatial structure of the coherent wave field is then calculated including cyclotron harmonic damping as compared to the usual procedure of incoherently summing powers of individual radiators. This method has the advantage that phase information from localized radiating currents is globally retained so the directivity of the pickup antennas is correctly represented. Also, standing waves and wall reflections are automatically included.

  17. Ion cyclotron emission calculations using a 2D full wave numerical code

    Energy Technology Data Exchange (ETDEWEB)

    Batchelor, D.B.; Jaeger, E.F.; Colestock, P.L.

    1987-09-01

    Measurement of radiation in the HF band due to cyclotron emission by energetic ions produced by fusion reactions or neutral beam injection promises to be a useful diagnostic on large devices which are entering the reactor regime of operation. A number of complications make the modelling and interpretation of such measurements difficult using conventional geometrical optics methods. In particular the long wavelength and lack of high directivity of antennas in this frequency regime make observation of a single path across the plasma into a viewing dump impractical. Pickup antennas effectively see the whole plasma and wall reflection effects are important. We have modified our 2D full wave ICRH code/sup 2/ to calculate wave fields due to a distribution of energetic ions in tokamak geometry. The radiation is modeled as due to an ensemble of localized source currents distributed in space. The spatial structure of the coherent wave field is then calculated including cyclotron harmonic damping as compared to the usual procedure of incoherently summing powers of individual radiators. This method has the advantage that phase information from localized radiating currents is globally retained so the directivity of the pickup antennas is correctly represented. Also standing waves and wall reflections are automatically included.

  18. Ion cyclotron emission calculations using a 2D full wave numerical code

    Science.gov (United States)

    Batchelor, D. B.; Jaeger, E. F.; Colestock, P. L.

    1987-09-01

    Measurement of radiation in the HF band due to cyclotron emission by energetic ions produced by fusion reactions or neutral beam injection promises to be a useful diagnostic on large devices which are entering the reactor regime of operation. A number of complications make the modelling and interpretation of such measurements difficult using conventional geometrical optics methods. In particular the long wavelength and lack of high directivity of antennas in this frequency regime make observation of a single path across the plasma into a viewing dump impractical. Pickup antennas effectively see the whole plasma and wall reflection effects are important. We have modified our 2D full wave ICRH code2 to calculate wave fields due to a distribution of energetic ions in tokamak geometry. The radiation is modeled as due to an ensemble of localized source currents distributed in space. The spatial structure of the coherent wave field is then calculated including cyclotron harmonic damping as compared to the usual procedure of incoherently summing powers of individual radiators. This method has the advantage that phase information from localized radiating currents is globally retained so the directivity of the pickup antennas is correctly represented. Also standing waves and wall reflections are automatically included.

  19. Optical Multi-hysteresises and "Rogue Waves" in Nonlinear Plasma

    CERN Document Server

    Kaplan, A E

    2010-01-01

    An overdense plasma layer irradiated by an intense light can exhibit dramatic nonlinear-optical effects due to a relativistic mass-effect of free electrons: highly-multiple hysteresises of reflection and transition, and emergence of gigantic "rogue waves". Those are trapped quasi-soliton field spikes inside the layer, sustained by an incident radiation with a tiny fraction of their peak intensity once they have been excited by orders of magnitude larger pumping. The phenomenon persists even in the layers with "soft" boundaries, as well as in a semi-infinite plasma with low absorption.

  20. Degenerate mixing of plasma waves on cold, magnetized single-species plasmas

    Science.gov (United States)

    Anderson, M. W.; O'Neil, T. M.; Dubin, D. H. E.; Gould, R. W.

    2011-10-01

    In the cold-fluid dispersion relation ω =ωp/[1+(k⊥/kz)2]1/2 for Trivelpiece-Gould waves on an infinitely long magnetized plasma cylinder, the transverse and axial wavenumbers appear only in the combination k⊥/kz. As a result, for any frequency ω Dubin modes), a perturbation analysis is used to investigate the mixing of low-order, nearly degenerate Dubin modes caused by small deformations of a plasma spheroid.

  1. Resonant scattering of plasma sheet electrons leading to diffuse auroral precipitation: 1. Evaluation for electrostatic electron cyclotron harmonic waves

    Science.gov (United States)

    Ni, Binbin; Thorne, Richard M.; Horne, Richard B.; Meredith, Nigel P.; Shprits, Yuri Y.; Chen, Lunjin; Li, Wen

    2011-04-01

    Using statistical wave power spectral profiles obtained from CRRES and the latitudinal distributions of wave propagation modeled by the HOTRAY code, a quantitative analysis has been performed on the scattering of plasma sheet electrons into the diffuse auroral zone by multiband electrostatic electron cyclotron harmonic (ECH) emissions near L = 6 within the 0000-0600 MLT sector. The results show that ECH wave scattering of plasma sheet electrons varies from near the strong diffusion rate (timescale of an hour or less) during active times with peak wave amplitudes of an order of 1 mV/m to very weak scattering (on the timescale of >1 day) during quiet conditions with typical wave amplitudes of tenths of mV/m. However, for the low-energy (˜100 eV to below 2 keV) electron population mainly associated with the diffuse auroral emission, ECH waves are only responsible for rapid pitch angle diffusion (occasionally near the limit of strong diffusion) for a small portion of the electron population with pitch angles αeq 70°. Computations of the bounce-averaged coefficients of momentum diffusion and (pitch angle, momentum) mixed diffusion indicate that both mixed diffusion and energy diffusion of plasma sheet electrons due to ECH waves are very small compared to pitch angle diffusion and that ECH waves have little effect on local electron acceleration. Consequently, the multiple harmonic ECH emissions cannot play a dominant role in the occurrence of diffuse auroral precipitation near L = 6, and other wave-particle interaction mechanisms, such as whistler mode chorus-driven resonant scattering, are required to explain the global distribution of diffuse auroral precipitation and the formation of the pancake distribution in the inner magnetosphere.

  2. Vertical Electron Cyclotron Emission Diagnostic for TCV Plasmas

    Directory of Open Access Journals (Sweden)

    Goodman T. P.

    2012-09-01

    Full Text Available Electron cyclotron resonance heating (ECRH and electron cyclotron current drive (ECCD are used to heat the plasma, to tailor the current profiles and to achieve different operating regimes of tokamak plasmas. Plasmas with ECRH/ECCD are characterized by non-thermal electrons, which cannot be described by a Maxwellian distribution. Non-thermal electrons are also generated during MHD activity, like sawteeth crashes. Quantifying the non-thermal electron distribution is therefore a key for understanding EC heated fusion plasmas. For this purpose a vertical electron cyclotron emission (V-ECE diagnostic is being installed at TCV. The diagnostic layout, the calibration, the analysis technique for data interpretation, the physics potentials and limitations are discussed.

  3. Dust-acoustic waves and stability in the permeating dust plasma: II. Power-law distributions

    CERN Document Server

    Gong, Jingyu; Du, Jiulin

    2012-01-01

    The dust-acoustic waves and their stability driven by a flowing dust plasma when it cross through a static (target) dust plasma (the so-called permeating dust plasma) are investigated when the components of the dust plasma obey the power-law q-distributions in nonextensive statistics. The frequency, the growth rate and the stability condition of the dust-acoustic waves are derived under this physical situation, which express the effects of the nonextensivity as well as the flowing dust plasma velocity on the dust-acoustic waves in this dust plasma. The numerical results illustrate some new characteristics of the dust-acoustic waves, which are different from those in the permeating dust plasma when the plasma components are the Maxwellian distribution. In addition, we show that the flowing dust plasma velocity has a significant effect on the dust-acoustic waves in the permeating dust plasma with the power-law q-distribution.

  4. Dust acoustic waves in strongly coupled dissipative plasmas

    Science.gov (United States)

    Xie, B. S.; Yu, M. Y.

    2000-12-01

    The theory of dust acoustic waves is revisited in the frame of the generalized viscoelastic hydrodynamic theory for highly correlated dusts. Physical processes relevant to many experiments on dusts in plasmas, such as ionization and recombination, dust-charge variation, elastic electron and ion collisions with neutral and charged dust particles, as well as relaxation due to strong dust coupling, are taken into account. These processes can be on similar time scales and are thus important for the conservation of particles and momenta in a self-consistent description of the system. It is shown that the dispersion properties of the dust acoustic waves are determined by a sensitive balance of the effects of strong dust coupling and collisional relaxation. The predictions of the present theory applicable to typical parameters in laboratory strongly coupled dusty plasmas are given and compared with the experiment results. Some possible implications and discrepanies between theory and experiment are also discussed.

  5. Nonlinear electrostatic wave equations for magnetized plasmas - II

    DEFF Research Database (Denmark)

    Dysthe, K. B.; Mjølhus, E.; Pécseli, H. L.

    1985-01-01

    For pt.I see ibid., vol.26, p.443-7 (1984). The problem of extending the high frequency part of the Zakharov equations for nonlinear electrostatic waves to magnetized plasmas, is considered. Weak electromagnetic and thermal effects are retained on an equal footing. Direction dependent (electrosta......For pt.I see ibid., vol.26, p.443-7 (1984). The problem of extending the high frequency part of the Zakharov equations for nonlinear electrostatic waves to magnetized plasmas, is considered. Weak electromagnetic and thermal effects are retained on an equal footing. Direction dependent...... (electrostatic) cut-off implies that various cases must be considered separately, leading to equations with rather different properties. Various equations encountered previously in the literature are recovered as limiting cases....

  6. Drift waves and chaos in a LAPTAG plasma physics experiment

    Science.gov (United States)

    Gekelman, Walter; Pribyl, Patrick; Birge-Lee, Henry; Wise, Joe; Katz, Cami; Wolman, Ben; Baker, Bob; Marmie, Ken; Patankar, Vedang; Bridges, Gabriel; Buckley-Bonanno, Samuel; Buckley, Susan; Ge, Andrew; Thomas, Sam

    2016-02-01

    In a project involving an alliance between universities and high schools, a magnetized plasma column with a steep pressure gradient was established in an experimental device. A two-dimensional probe measured fluctuations in the plasma column in a plane transverse to the background magnetic field. Correlation techniques determined that the fluctuations were that of electrostatic drift waves. The time series data were used to generate the Bandt-Pompe entropy and Jensen-Shannon complexity for the data. These quantities, when plotted against one another, revealed that a combination of drift waves and other background fluctuations were a deterministically chaotic system. Our analysis can be used to tell the difference between deterministic chaos and random noise, making it a potentially useful technique in nonlinear dynamics.

  7. PLASMA EMISSION BY COUNTER-STREAMING ELECTRON BEAMS

    Energy Technology Data Exchange (ETDEWEB)

    Ziebell, L. F.; Petruzzellis, L. T.; Gaelzer, R. [Instituto de Física, UFRGS, Porto Alegre, RS (Brazil); Yoon, P. H. [Institute for Physical Science and Technology, University of Maryland, College Park, MD (United States); Pavan, J., E-mail: luiz.ziebell@ufrgs.br, E-mail: yoonp@umd.edu, E-mail: joel.pavan@ufpel.edu.br [Instituto de Física e Matemática, UFPel, Pelotas, RS (Brazil)

    2016-02-10

    The radiation emission mechanism responsible for both type-II and type-III solar radio bursts is commonly accepted as plasma emission. Recently Ganse et al. suggested that type-II radio bursts may be enhanced when the electron foreshock geometry of a coronal mass ejection contains a double hump structure. They reasoned that the counter-streaming electron beams that exist between the double shocks may enhance the nonlinear coalescence interaction, thereby giving rise to more efficient generation of radiation. Ganse et al. employed a particle-in-cell simulation to study such a scenario. The present paper revisits the same problem with EM weak turbulence theory, and show that the fundamental (F) emission is not greatly affected by the presence of counter-streaming beams, but the harmonic (H) emission becomes somewhat more effective when the two beams are present. The present finding is thus complementary to the work by Ganse et al.

  8. Statistical Analysis of EMIC Waves in Multiple Component Plasma Including Heavy Ions

    Science.gov (United States)

    Matsuda, S.; Kasahara, Y.; Goto, Y.

    2013-12-01

    It is well known that Earth's radiation belts are located around geomagnetic equator, where wide ranges of energetic particles from several hundred keV to several tens MeV are contained. According to the recent study, it is suggested that ELF/VLF waves such as EMIC waves and chorus emissions deeply contribute to the generation and loss mechanism of relativistic electrons in the radiation belt. The ERG mission[1] is expected to provide important clues for solving plasma dynamics in the Earth's radiation belts by means of integrated observation of wide energy range of plasma particles and high resolution plasma waves. On the other hand, long-term observation data which covers over 2 cycles of solar activity obtained by the Akebono satellite is very valuable to work out the strategy of the ERG mission. The ELF receiver, which is a sub-system of the VLF instruments onboard Akebono, measures waveforms below 50 Hz for one component of electric field and three components of magnetic field, or waveforms below 100 Hz for one component of electric and magnetic field, respectively. It was reported that ion cyclotron waves were observed near magnetic equator by the receiver[2]. In our previous study[3], we introduced four events of characteristic EMIC waves observed by Akebono in April, 1989. These waves have sudden decrease of intensity just above half of proton cyclotron frequency changing along the trajectories of Akebono. Comparing the observed data with the dispersion relation in multiple species of ions under cold plasma approximation, we demonstrate that a few percent of 'M / Z = 2 ions (M = mass of ions, Z = charge of ions)' such as alpha particles (He++) or deuterons (D+) cause such characteristic attenuation of EMIC at lower hybrid frequency. In the present study, we performed polarization analysis and direction finding of the waves. It was found that these EMIC waves were left-handed polarized in the higher frequency part, while the polarization gradually changes to

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

    Directory of Open Access Journals (Sweden)

    G. Thejappa

    2013-08-01

    Full Text Available The high time resolution observations obtained by the STEREO/WAVES experiment show that in the source regions of solar type III radio bursts, Langmuir waves often occur as intense localized wave packets with short durations of only few ms. One of these wave packets shows that it is a three-dimensional field structure with WLneTe ~ 10−3, where WL is the peak energy density, and ne and Te are the electron density and temperature, respectively. For this wave packet, the conditions of the oscillating two-stream instability (OTSI and supersonic collapse are satisfied within the error range of determination of main parameters. The density cavity, observed during this wave packet indicates that its depth, width and temporal coincidence are consistent with those of a caviton, generated by the ponderomotive force of the collapsing wave packet. The spectrum of each of the parallel and perpendicular components of the wave packet contains a primary peak at fpe, two secondary peaks at fpe ± fS and a low-frequency enhancement below fS, which, as indicated by the frequency and wave number resonance conditions, and the fast Fourier transform (FFT-based tricoherence spectral peak at (fpe, fpe, fpe + fS, fpe − fS, are coupled to each other by the OTSI type of four-wave interaction (fpe is the local electron plasma frequency and fS is the frequency of ion sound waves. In addition to the primary peak at fpe, each of these spectra also contains a peak at 2fpe, which as indicated by the frequency and wave number resonance conditions, and the wavelet-based bicoherence spectral peak at (fpe, fpe, appears to correspond to the second harmonic electromagnetic waves generated as a result of coalescence of oppositely propagating sidebands excited by the OTSI. Thus, these observations for the first time provide combined evidence that (1 the OTSI and related strong turbulence processes play a significant role in the stabilization of the electron beam, (2 the coalescence

  10. Structures of Strong Shock Waves in Dense Plasmas

    Institute of Scientific and Technical Information of China (English)

    JIANG Zhong-He; HE Yong; HU Xi-Wei; LV Jian-Hong; HU Ye-Min

    2007-01-01

    @@ Structures of strong shock waves in dense plasmas are investigated via the steady-state Navier-Stokes equations and Poisson equation. The structures from fluid simulation agree with the ones from kinetic simulation. The effects of the transport coefficients on the structures are analysed. The enhancements of the electronic heat conduction and ionic viscosity both will broaden the width of the shock fronts, and decrease the electric fields in the fronts.

  11. Secondary electron emission from plasma-generated nanostructured tungsten fuzz

    Science.gov (United States)

    Patino, M.; Raitses, Y.; Wirz, R.

    2016-11-01

    Recently, several researchers [e.g., Yang et al., Sci. Rep. 5, 10959 (2015)] have shown that tungsten fuzz can grow on a hot tungsten surface under bombardment by energetic helium ions in different plasma discharges and applications, including magnetic fusion devices with plasma facing tungsten components. This work reports the direct measurements of the total effective secondary electron emission (SEE) from tungsten fuzz. Using dedicated material surface diagnostics and in-situ characterization, we find two important results: (1) SEE values for tungsten fuzz are 40%-63% lower than for smooth tungsten and (2) the SEE values for tungsten fuzz are independent of the angle of the incident electron. The reduction in SEE from tungsten fuzz is most pronounced at high incident angles, which has important implications for many plasma devices since in a negative-going sheath the potential structure leads to relatively high incident angles for the electrons at the plasma confining walls. Overall, low SEE will create a relatively higher sheath potential difference that reduces plasma electron energy loss to the confining wall. Thus, the presence or self-generation in a plasma of a low SEE surface such as tungsten fuzz can be desirable for improved performance of many plasma devices.

  12. Secondary fast magnetoacoustic waves trapped in randomly structured plasmas

    CERN Document Server

    Yuan, Ding; Walsh, Robert W

    2016-01-01

    Fast magnetoacoustic wave is an important tool for inferring solar atmospheric parameters. We numerically simulate the propagation of fast wave pulses in randomly structured plasmas mimicking the highly inhomogeneous solar corona. A network of secondary waves is formed by a series of partial reflections and transmissions. These secondary waves exhibit quasi-periodicities in both time and space. Since the temporal and spatial periods are related simply through the fast wave speed, we quantify the properties of secondary waves by examining the dependence of the average temporal period ($\\bar{p}$) on the initial pulse width ($w_0$) as well as the density contrast ($\\delta_\\rho$) and correlation length ($L_c$) that characterize the randomness of the equilibrium density profiles. For small-amplitude pulses, $\\delta_\\rho$ does not alter $\\bar{p}$ significantly. Large-amplitude pulses, on the other hand, enhance the density contrast when $\\delta_\\rho$ is small but have a smoothing effect when $\\delta_\\rho$ is suffic...

  13. LASER PLASMA AND LASER APPLICATIONS: Plasma transparency in laser absorption waves in metal capillaries

    Science.gov (United States)

    Anisimov, V. N.; Kozolupenko, A. P.; Sebrant, A. Yu

    1988-12-01

    An experimental investigation was made of the plasma transparency to heating radiation in capillaries when absorption waves propagated in these capillaries as a result of interaction with a CO2 laser pulse of 5-μs duration. When the length of the capillary was in excess of 20 mm, total absorption of the radiation by the plasma was observed at air pressures of 1-100 kPa. When the capillary length was 12 mm, a partial recovery of the transparency took place. A comparison was made with the dynamics and recovery of the plasma transparency when breakdown of air took place near the free surface.

  14. 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.

  15. FDTD Simulation on Terahertz Waves Propagation Through a Dusty Plasma

    Science.gov (United States)

    Wang, Maoyan; Zhang, Meng; Li, Guiping; Jiang, Baojun; Zhang, Xiaochuan; Xu, Jun

    2016-08-01

    The frequency dependent permittivity for dusty plasmas is provided by introducing the charging response factor and charge relaxation rate of airborne particles. The field equations that describe the characteristics of Terahertz (THz) waves propagation in a dusty plasma sheath are derived and discretized on the basis of the auxiliary differential equation (ADE) in the finite difference time domain (FDTD) method. Compared with numerical solutions in reference, the accuracy for the ADE FDTD method is validated. The reflection property of the metal Aluminum interlayer of the sheath at THz frequencies is discussed. The effects of the thickness, effective collision frequency, airborne particle density, and charge relaxation rate of airborne particles on the electromagnetic properties of Terahertz waves through a dusty plasma slab are investigated. Finally, some potential applications for Terahertz waves in information and communication are analyzed. supported by National Natural Science Foundation of China (Nos. 41104097, 11504252, 61201007, 41304119), the Fundamental Research Funds for the Central Universities (Nos. ZYGX2015J039, ZYGX2015J041), and the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20120185120012)

  16. Propagation and Generation of Electromagnetic Waves at Proton Gyrofrequencies in a Relativistic Electron-Positron Plasma. II. Excitation of Electromagnetic Waves

    Science.gov (United States)

    Zheleznyakov, V. V.; Bespalov, P. A.

    2016-04-01

    In part I of this work [1], we study the dispersion characteristics of low-frequency waves in a relativistic electron-positron plasma. In part II, we examine the electromagnetic wave instability in this plasma caused by an admixture of nonrelativistic protons with energy comparable with the energy of relativistic low-mass particles. The instability occurs in the frequency band between the fundamental harmonic of proton gyrofrequency and the fundamental harmonic of relativistic electron gyrofrequency. The results can be used for the interpretation of known observations of the pulsar emissions obtained with a high time and frequency resolution. The considered instability can probably be the initial stage of the microwave radio emission nanoshots typical of the pulsar in the Crab Nebula.

  17. Characteristics of extreme ultraviolet emission from high-Z plasmas

    Science.gov (United States)

    Ohashi, H.; Higashiguchi, T.; Suzuki, Y.; Kawasaki, M.; Suzuki, C.; Tomita, K.; Nishikino, M.; Fujioka, S.; Endo, A.; Li, B.; Otsuka, T.; Dunne, P.; O'Sullivan, G.

    2016-03-01

    We demonstrate the extreme ultraviolet (EUV) and soft x-ray sources in the 2 to 7 nm spectral region related to the beyond EUV (BEUV) question at 6.x nm and the water window source based on laser-produced high-Z plasmas. Resonance emission from multiply charged ions merges to produce intense unresolved transition arrays (UTAs), extending below the carbon K edge (4.37 nm). An outline of a microscope design for single-shot live cell imaging is proposed based on high-Z plasma UTA source, coupled to multilayer mirror optics.

  18. Nonlinear electromagnetic waves in a degenerate electron-positron plasma

    Energy Technology Data Exchange (ETDEWEB)

    El-Labany, S.K., E-mail: skellabany@hotmail.com [Department of Physics, Faculty of Science, Damietta University, New Damietta (Egypt); El-Taibany, W.F., E-mail: eltaibany@hotmail.com [Department of Physics, College of Science for Girls in Abha, King Khalid University, Abha (Saudi Arabia); El-Samahy, A.E.; Hafez, A.M.; Atteya, A., E-mail: ahmedsamahy@yahoo.com, E-mail: am.hafez@sci.alex.edu.eg, E-mail: ahmed_ateya2002@yahoo.com [Department of Physics, Faculty of Science, Alexandria University, Alexandria (Egypt)

    2015-08-15

    Using the reductive perturbation technique (RPT), the nonlinear propagation of magnetosonic solitary waves in an ultracold, degenerate (extremely dense) electron-positron (EP) plasma (containing ultracold, degenerate electron, and positron fluids) is investigated. The set of basic equations is reduced to a Korteweg-de Vries (KdV) equation for the lowest-order perturbed magnetic field and to a KdV type equation for the higher-order perturbed magnetic field. The solutions of these evolution equations are obtained. For better accuracy and searching on new features, the new solutions are analyzed numerically based on compact objects (white dwarf) parameters. It is found that including the higher-order corrections results as a reduction (increment) of the fast (slow) electromagnetic wave amplitude but the wave width is increased in both cases. The ranges where the RPT can describe adequately the total magnetic field including different conditions are discussed. (author)

  19. Characteristics of Wave-Particle Interaction in a Hydrogen Plasma

    Institute of Scientific and Technical Information of China (English)

    HE Hui-Yong; CHEN Liang-Xu; LI Jiang-Fan

    2008-01-01

    We study the characteristics of cyclotron wave-particle interaction in a typical hydrogen plasma. The numerical calculations of minimum resonant energy Emin, resonant wave frequency w, and pitch angle diffusion coefficient Dαα for interactions between R-mode/L-mode and electrons/protons are presented. It is found that Emin decreases with ω for R-mode/electron, L-mode/proton and L-mode/electron interactions, but increase with w for R-mode/proton interaction. It is shown that both R-mode and L-mode waves can efficiently scatter energetic (10 keV~100 keV) electrons and protons and cause precipitation loss at L=4, indicating that perhaps waveparticle interaction is a serious candidate for the ring current decay.

  20. Nonlinear Electromagnetic Waves in a Degenerate Electron-Positron Plasma

    Science.gov (United States)

    El-Labany, S. K.; El-Taibany, W. F.; El-Samahy, A. E.; Hafez, A. M.; Atteya, A.

    2015-08-01

    Using the reductive perturbation technique (RPT), the nonlinear propagation of magnetosonic solitary waves in an ultracold, degenerate (extremely dense) electron-positron (EP) plasma (containing ultracold, degenerate electron, and positron fluids) is investigated. The set of basic equations is reduced to a Korteweg-de Vries (KdV) equation for the lowest-order perturbed magnetic field and to a KdV type equation for the higher-order perturbed magnetic field. The solutions of these evolution equations are obtained. For better accuracy and searching on new features, the new solutions are analyzed numerically based on compact objects (white dwarf) parameters. It is found that including the higher-order corrections results as a reduction (increment) of the fast (slow) electromagnetic wave amplitude but the wave width is increased in both cases. The ranges where the RPT can describe adequately the total magnetic field including different conditions are discussed.

  1. Fusion plasma diagnostics with mm-waves an introduction

    CERN Document Server

    Hartfuss, Hans-Jürgen

    2013-01-01

    Filling a gap in the literature, this introduction to the topic covers the physics of the standard microwave diagnostics established on modern fusion experiments, and the necessary technological background from the field of microwave engineering. Written by well-known mm-wave diagnosticians in the field of fusion physics, the textbook includes such major diagnostic techniques as electron cyclotron emission, interferometry, reflectometry, polarimetry, and scattering.

  2. On Plasma Rotation Induced by Traveling Fast Alfvin Waves

    Energy Technology Data Exchange (ETDEWEB)

    F.W. Perkins; R.B. White; and V.S. Chan

    2001-08-09

    Absorption of fast Alfven waves by the minority fundamental ion-cyclotron resonance, coupled with finite banana width physics, generates torque distributions and ultimately rotational shear layers in the bulk plasma, even when the toroidal wavenumber k(subscript ''phi'') = n/R of the fast wave vanishes (n=0) and cyclotron absorption introduces no angular momentum nor canonical angular momentum [F.W. Perkins, R.B. White, P.T. Bonoli, and V.S. Chan, Phys. Plasmas 8 (2001) 2181]. The present work extends these results to travelling waves with non-zero n where heating directly introduces angular momentum. Since tokamak fast-wave antennas have approximately one wavelength per toroidal field coil, the toroidal mode number n lies in the range n = 10-20, independent of machine size. A zero-dimensional analysis shows that the rotation rate arising from direct torque is comparable to that of the rotational shear layer and has the same scaling. Nondimensional rotation profiles for n = (-10, 10) show modest changes from the n = 0 case in the expected direction. For a balanced antenna spectrum, the nondimensional rotational profile (averaged over n = -10, 10) lies quite close to the n = 0 profile.

  3. High harmonic fast waves in high beta plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Masayuki

    1995-04-01

    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 ({approximately} 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 ({beta}{sub i} = 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 {alpha}-heating does not appear to modify the accessibility condition nor cause excessive wave absorption.

  4. NOx Emissions from a Rotating Detonation-wave Engine

    Science.gov (United States)

    Kailasanath, Kazhikathra; Schwer, Douglas

    2016-11-01

    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. Results to date show that NOx emissions are not a problem for the RDE due to the short residence times and the nature of the flow field. Furthermore, simulations show that the amount of NOx can be further reduced by tailoring the fluid dynamics within the RDE.

  5. Low frequency waves in streaming quantum dusty plasmas

    Science.gov (United States)

    Rozina, Ch.; Jamil, M.; Khan, Arroj A.; Zeba, I.; Saman, J.

    2017-09-01

    The influence of quantum effects on the excitation of two instabilities, namely quantum dust-acoustic and quantum dust-lower-hybrid waves due to the free streaming of ion/dust particles in uniformly magnetized dusty plasmas has been investigated using a quantum hydrodynamic model. We have obtained dispersion relations under some particular conditions applied on streaming ions and two contrastreaming dust particle beams at equilibrium and have analyzed the growth rates graphically. We have shown that with the increase of both the electron number density and the streaming speed of ion there is enhancement in the instability due to the fact that the dense plasma particle system with more energetic species having a high speed results in the increase of the growth rate in the electrostatic mode. The application of this work has been pointed out for laboratory as well as for space dusty plasmas.

  6. Dynamic Thomson Scattering from Nonlinear Electron Plasma Waves in a Raman Plasma Amplifier

    Science.gov (United States)

    Davies, A.; Katz, J.; Bucht, S.; Haberberger, D.; Bromage, J.; Zuegel, J. D.; Froula, D. H.; Trines, R.; Bingham, R.; Sadler, J.; Norreys, P. A.

    2016-10-01

    Electron plasma waves (EPW's) can be used to transfer significant energy from a long-pulse laser to a short-pulse seed laser through the Raman scattering instability. Successful implementation of Raman amplification could open an avenue to producing high-intensity pulses beyond the capabilities of current laser technology ( 1022 W / cm 2). This three-wave interaction takes advantage of the plasma's ability to sustain large-amplitude plasma waves. Having complete knowledge of the EPW amplitude is essential to establishing optimal parameters for high-efficiency Raman amplification. A dynamic Thomson-scattering diagnostic is being developed to spatially and temporally resolve the amplitude of the driven and thermal EPW's. By imaging the scattered probe light onto a novel pulse-front tilt compensated streaked optical spectrometer, the diffraction efficiency of this plasma wave can be measured as a function of space and time. These data will be used in conjunction with particle-in-cell simulations to determine the EPW's spatial and temporal profile. This will allow the effect of the EPW profile on Raman scattering to be experimentally determined. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  7. Laser plasma simulations of the generation processes of Alfven and collisionless shock waves in space plasma

    Science.gov (United States)

    Prokopov, P. A.; Zakharov, Yu P.; Tishchenko, V. N.; Shaikhislamov, I. F.; Boyarintsev, E. L.; Melekhov, A. V.; Ponomarenko, A. G.; Posukh, V. G.; Terekhin, V. A.

    2016-11-01

    Generation of Alfven waves propagating along external magnetic field B0 and Collisionless Shock Waves propagating across B0 are studied in experiments with laser- produced plasma and magnetized background plasma. The collisionless interaction of interpenetrating plasma flows takes place through a so-called Magnetic Laminar Mechanism (MLM) or Larmor Coupling. At the edge of diamagnetic cavity LP-ions produce induction electric field Eφ which accelerates BP-ions while LP-ions rotate in opposite direction. The ions movement generates sheared azimuthal magnetic field Bφ which could launches torsional Alfven wave. In previous experiments at KI-1 large scale facility a generation of strong perturbations propagating across B0 with magnetosonic speed has been studied at a moderate value of interaction parameter δ∼0.3. In the present work we report on experiments at conditions of 5∼R2 and large Alfven-Mach number MA∼10 in which strong transverse perturbations traveling at a scale of ∼1 m in background plasma at a density of ∼3*1013 cm-3 is observed. At the same conditions but smaller MA ∼ 2 a generation, the structure and dynamic of Alfven wave with wavelength ∼0.5 m propagating along fields B0∼100÷500 G for a distance of ∼2.5 m is studied.

  8. Electron Bernstein waves emission in the TJ-II stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Regana, J M; Cappa, A; Castejon, F; Ros, A [Laboratorio Nacional de Fusion, CIEMAT, 28040, Madrid (Spain); Caughman, J B O; Rasmussen, D A; Wilgen, J B [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Tereshchenko, M, E-mail: josemanuel.garcia@ciemat.es [Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2011-06-15

    Taking advantage of the electron Bernstein waves heating system of the TJ-II stellarator, an electron Bernstein emission (EBE) diagnostic was installed. Its purpose is to investigate the B-X-O radiation properties in the zone where optimum theoretical electron Bernstein wave (EBW) coupling is predicted. An internal movable mirror shared by both systems allows us to collect the EBE radiation along the same line of sight that is used for EBW heating. The theoretical EBE has been calculated for different orientations of the internal mirror using the TRUBA code as the ray tracer. A comparison with experimental data obtained in NBI discharges is carried out. The results provide valuable information regarding the experimental O-X-mode conversion window expected in the EBW heating experiments. Furthermore, the characterization of the radiation polarization shows evidence of the underlying B-X-O conversion process.

  9. Decoherence of matter waves by thermal emission of radiation

    CERN Document Server

    Hackermüller, L; Brezger, B; Zeilinger, Anton; Arndt, M; Hackermueller, Lucia; Hornberger, Klaus; Brezger, Bjoern; Zeilinger, Anton; Arndt, Markus

    2004-01-01

    Emergent quantum technologies have led to increasing interest in decoherence - the processes that limit the appearance of quantum effects and turn them into classical phenomena. One important cause of decoherence is the interaction of a quantum system with its environment, which 'entangles' the two and distributes the quantum coherence over so many degrees of freedom as to render it unobservable. Decoherence theory has been complemented by experiments using matter waves coupled to external photons or molecules, and by investigations using coherent photon states, trapped ions and electron interferometers. Large molecules are particularly suitable for the investigation of the quantum-classical transition because they can store much energy in numerous internal degrees of freedom; the internal energy can be converted into thermal radiation and thus induce decoherence. Here we report matter wave interferometer experiments in which C70 molecules lose their quantum behaviour by thermal emission of radiation. We find...

  10. 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

    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.

  11. 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

  12. Laser light scattering in a laser-induced argon plasma: Investigations of the shock wave

    Energy Technology Data Exchange (ETDEWEB)

    Pokrzywka, B. [Obserwatorium Astronomiczne na Suhorze, Uniwersytet Pedagogiczny, ulica Podchorazych 2, 30-084 Krakow (Poland); Mendys, A., E-mail: agata.mendys@uj.edu.pl [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagiellonski, ulica Reymonta 4, 30-059 Krakow (Poland); Dzierzega, K.; Grabiec, M. [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagiellonski, ulica Reymonta 4, 30-059 Krakow (Poland); Pellerin, S. [GREMI, site de Bourges, Universite d' Orleans, CNRS, rue Gaston Berger BP 4043, 18028 Bourges (France)

    2012-08-15

    Shock wave produced by a laser induced spark in argon at atmospheric pressure was examined using Rayleigh and Thomson scattering. The spark was generated by focusing a laser pulse from the second harmonic ({lambda} = 532 nm) of a nanosecond Nd:YAG laser using an 80 mm focal length lens, with a fluence of 2 kJ{center_dot}cm{sup -2}. Images of the spark emission were recorded for times between 30 ns and 100 {mu}s after the laser pulse in order to characterize its spatial evolution. The position of the shock wave at several instants of its evolution and for several plasma regions was determined from the Rayleigh-scattered light of another nanosecond Nd:YAG laser (532 nm, 40 J{center_dot}cm{sup -2} fluence). Simultaneously, Thomson scattering technique was applied to determine the electron density and temperature in the hot plasma core. Attempts were made to describe the temporal evolution of the shock wave within a self-similar model, both by the simple Sedov-Taylor formula as well as its extension deduced by de Izarra. The temporal radial evolution of the shock position is similar to that obtained within theory taking into account the counter pressure of the ambient gas. Density profiles just behind the shock front are in qualitative agreement with those obtained by numerically solving the Euler equations for instantaneous explosion at a point with counter pressure. - Highlights: Black-Right-Pointing-Pointer We investigated shock wave evolution by Rayleigh scattering method. Black-Right-Pointing-Pointer 2D map of shockwave position for several times after plasma generation is presented. Black-Right-Pointing-Pointer Shock wave evolution is not satisfactorily described within self-similar models. Black-Right-Pointing-Pointer Evolution of shock position similar to theory taking into account counter pressure. Black-Right-Pointing-Pointer Density profile behind the shock similar to numerical solution of Euler equations.

  13. Scattering of Electromagnetic Waves by Drift Vortex in Plasma

    Institute of Scientific and Technical Information of China (English)

    WANG Dong; CHEN Yinhua; WANG Ge

    2008-01-01

    In a quasi-two-dimensional model, the scattering of incident ordinary electromag-netic waves by a dipole-electrostatic drift vortex is studied with first-order Born approximation. The distribution of the scattering cross-section and total cross-section are evaluated analytically in different approximate conditions, and the physical interpretations are discussed. When the wavelength of incident wave is much longer than the vortex radius (kia << 1), it is found that the angle at which the scattering cross-section reaches its maxim depends significantly on the approxi-mation of the parameters of the vortex used. It is also found that the total scattering cross-section has an affinitive relation with the parameters of the plasma, while it is irrelevant to the frequency of the incident wave in a wide range of parameters of the vortex. In a totally different range of parameters when incident wave is in the radar-frequency range (then ki<< 1, the wavelength of incident wave is much shorter than the vortex radius), the numerical procedure is conducted with computer in order to obtain the distribution and the total expression of the scattering cross-section. Then it is found that the total scattering cross-section in the low frequency range is much larger than that in high frequency range, so the scattering is more effective in the low frequency range than in high frequency range.

  14. Decay of Langmuir wave in dense plasmas and warm dense matter

    CERN Document Server

    Son, S; Moon, Sung Joon

    2010-01-01

    The decays of the Langmuir waves in dense plasmas are computed using the dielectric function theory widely used in the solid state physics. Four cases are considered: a classical plasma, a Maxwellian plasma, a degenerate quantum plasma, and a partially degenerate plasma. The result is considerably different from the conventional Landau damping theory.

  15. On the Self-Focusing of Whistler Waves in a Radial Inhomogeneous Plasma

    DEFF Research Database (Denmark)

    Balmashnov, A. A.

    1980-01-01

    The process of whistler wave self-focusing is experimentally investigated. It was found that a whistler wave propagating along the plasma column with a density crest excites a longitudinal wave of the same frequency propagating across the external magnetic field. The amplitude modulation...... of the latter wave is accompanied by a density modification, which leads to trapping of the whistler wave in a density trough in the center of the plasma column....

  16. Cascade emission in electron beam ion trap plasma

    CERN Document Server

    Jonauskas, Valda; Kyniene, Ausra; Kucas, Sigitas

    2013-01-01

    We present investigation of the influence of cascade emission to the formation of spectra from plasma created by electron beam ion trap (EBIT) in electron trapping mode. It has been shown that cascade emission can play an important role in the formation of spectra from the EBIT plasma. Process of the cascade emission takes place when ion having cycloidal orbit leaves electron beam where coronal approximation is applicable. Thus both processes - excitation from ground or metastable levels and cascade emission - take part in the population of levels. Demonstration is based on the investigation of $W^{13+}$ spectra. The present investigation helps to resolve long-standing discrepancies; in particular, the present structure of $W^{13+}$ spectra is in good agreement with measurements on electron beam ion trap. Lines in the experimental spectra are identified as $4f^{13} 5s 5p \\rightarrow 4f^{13} 5s^{2}$ and $4f^{12} 5s 5p^{2} \\rightarrow 4f^{12} 5s^{2} 5p$ transitions from Dirac-Fock-Slater calculations.

  17. Bohm potential effect on the propagation of electrostatic surface wave in semi-bounded quantum plasmas

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-02-01

    High frequency electrostatic wave propagation in a dense and semi-bounded electron quantum plasma is investigated with consideration of the Bohm potential. The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. We found that the quantum effect enhances the frequency of the wave especially in the high wave number regime. However, the frequency of surface wave is found to be always lower than that of the bulk wave for the same quantum wave number. The group velocity of the surface wave for various quantum wave number is also obtained.

  18. Net Emission Coefficients for Copper and Iron Plasmas

    Science.gov (United States)

    Kassubek, Frank; Zilberberg, Oded; Doiron, Charles

    2016-09-01

    Radiative heat transfer is an important mechanism for heat transport in electrical arcs, e.g. in electrical switchgear. An exact description of this phenomenon is important (i) for the energy balance of the arc itself, and (ii) for the estimate of the escaping radiation that leads to evaporation of polymer nozzles; the evaporated material and its flow have a strong effect on the arcs. For low voltage arcs, the plasma composition within the arc is dominated by the contact material. In the present study, we compare copper and iron. Especially, we discuss the calculation of absorption and emission spectra and their characterisation by net emission coefficients. The latter describe well the effective power balance at the centre of the arc. We show that in addition to the net emission coefficients, it is important to characterise the radiation that is emitted from the arc core.

  19. Nonlinear processes in the strong wave-plasma interaction

    Science.gov (United States)

    Pegoraro, Francesco; Califano, Francesco; Attico, Nicola; Bulanov, Sergei

    2000-10-01

    Nonlinear interactions in hot laboratory and/or astrophysical plasmas are a very efficient mechanism able to transfer the energy from the large to the small spatial scales of the system. As a result, kinetic processes are excited and play a key role in the plasma dynamics since the typical fluid dissipative length scales (where the nonlinear cascade is stopped) are (much) smaller then the kinetic length scales. Then, the key point is the role of the kinetic effects in the global plasma dynamics, i.e. whether the kinetic effects remains confined to the small scales of the system or whether there is a significant feedback on the large scales. Here we will address this problem by discussing the nonlinear kinetic evolution of the electromagnetic beam plasma instability where phase space vortices, as well as large scale vortex like magnetic structures in the physical space, are generated by wave - particle interactions. The role and influence of kinetic effects on the large scale plasma dynamics will be also discussed by addressing the problem of collisionless magnetic reconection.

  20. 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.

  1. Kinetic theory of twisted waves: Application to space plasmas having superthermal population of species

    Science.gov (United States)

    Arshad, Kashif; Poedts, Stefaan; Lazar, Marian

    2017-04-01

    Nowadays electromagnetic (EM) fields have various applications in fundamental research, communication, and home appliances. Even though, there are still some subtle features of electromagnetic field known to us a century ago, yet to be utilized. It is because of the technical complexities to sense three dimensional electromagnetic field. An important characteristic of electromagnetic field is its orbital angular momentum (OAM). The angular momentum consists of two distinct parts; intrinsic part associated with the wave polarization or spin, and the extrinsic part associated with the orbital angular momentum (OAM). The orbital angular momentum (OAM) is inherited by helically phased light or helical (twisted) electric field. The investigations of Allen on lasers carrying orbital angular momentum (OAM), has initiated a new scientific and technological advancement in various growing fields, such as microscopy and imaging, atomic and nano-particle manipulation, ultra-fast optical communications, quantum computing, ionospheric radar facility to observe 3D plasma dynamics in ionosphere, photonic crystal fibre, OAM entanglement of two photons, twisted gravitational waves, ultra-intense twisted laser pulses and astrophysics. Recently, the plasma modes are also investigated with orbital angular momentum. The production of electron vortex beams and its applications are indicated by Verbeeck et al. The magnetic tornadoes (rotating magnetic field structures) exhibit three types of morphology i.e., spiral, ring and split. Leyser pumped helical radio beam carrying OAM into the Ionospheric plasma under High Frequency Active Auroral Research Program (HAARP) and characteristic ring shaped morphology is obtained by the optical emission spectrum of pumped plasma turbulence. The scattering phenomenon like (stimulated Raman and Brillouin backscattering) is observed to be responsible for the interaction between electrostatic and electromagnetic waves through orbital angular momentum. The

  2. Study of nonlinear waves in astrophysical quantum plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hossen, M.R.; Mamun, A.A., E-mail: rasel.plasma@gmail.com [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh)

    2015-10-01

    The nonlinear propagation of the electron acoustic solitary waves (EASWs) in an unmagnetized, collisionless degenerate quantum plasma system has been investigated theoretically. Our considered model consisting of two distinct groups of electrons (one of inertial non-relativistic cold electrons and other of inertialess ultrarelativistic hot electrons) and positively charged static ions. The Korteweg-de Vries (K-dV) equation has been derived by employing the reductive perturbation method and numerically examined to identify the basic features (speed, amplitude, width, etc.) of EASWs. It is shown that only rarefactive solitary waves can propagate in such a quantum plasma system. It is found that the effect of degenerate pressure and number density of hot and cold electron fluids, and positively charged static ions, significantly modify the basic features of EASWs. It is also noted that the inertial cold electron fluid is the source of dispersion for EA waves and is responsible for the formation of solitary structures. The applications of this investigation in astrophysical compact objects (viz. non-rotating white dwarfs, neutron stars, etc.) are briefly discussed. (author)

  3. Coherent structures and transport in drift wave plasma turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Bang Korsholm, S.

    2011-12-15

    Fusion energy research aims at developing fusion power plants providing safe and clean energy with abundant fuels. Plasma turbulence induced transport of energy and particles is a performance limiting factor for fusion devices. Hence the understanding of plasma turbulence is important for optimization. The present work is a part of the puzzle to understand the basic physics of transport induced by drift wave turbulence in the edge region of a plasma. The basis for the study is the Hasegawa-Wakatani model. Simulation results for 3D periodic and nonperiodic geometries are presented. The Hasegawa-Wakatani model is further expanded to include ion temperature effects. Another expansion of the model is derived from the Braginskii electron temperature equation. The result is a self-consistent set of equations describing the dynamical evolution of the drift wave fluctuations of the electron density, electron temperature and the potential in the presence of density and temperature gradients. 3D simulation results of the models are presented. Finally, the construction and first results from the MAST fluctuation reflectometer is described. The results demonstrate how L- to H-mode transitions as well as edge-localized-modes can be detected by the relatively simple diagnostic system. The present Risoe report is a slightly updated version of my original PhD report which was submitted in April 2002 and defended in August 2002. (Author)

  4. The dust acoustic waves in three dimensional scalable complex plasma

    CERN Document Server

    Zhukhovitskii, D I

    2015-01-01

    Dust acoustic waves in the bulk of a dust cloud in complex plasma of low pressure gas discharge under microgravity conditions are considered. The dust component of complex plasma is assumed a scalable system that conforms to the ionization equation of state (IEOS) developed in our previous study. We find singular points of this IEOS that determine the behavior of the sound velocity in different regions of the cloud. The fluid approach is utilized to deduce the wave equation that includes the neutral drag term. It is shown that the sound velocity is fully defined by the particle compressibility, which is calculated on the basis of the scalable IEOS. The sound velocities and damping rates calculated for different 3D complex plasmas both in ac and dc discharges demonstrate a good correlation with experimental data that are within the limits of validity of the theory. The theory provides interpretation for the observed independence of the sound velocity on the coordinate and for a weak dependence on the particle ...

  5. Radio and Plasma Waves Synergistic Science Opportunities with EJSM

    Science.gov (United States)

    Cecconi, Baptiste; André, Nicolas; Bougeret, Jean-Louis

    2010-05-01

    The radio and plasma wave (RPW) diagnostics provide a unique access to critical parameters of space plasma, in particular in planetary and satellite environments. Concerning giant planets, this has been demonstrated by major results obtained by the radio investigation on the Galileo and Cassini spacecraft, but also during the Ulysses, Voyager, and Pioneer flybys of Jupiter. Several other missions, past or in flight, demonstrate the uniqueness and relevance of RPW diagnostics to basic problems of astrophysics. The EJSM mission consists of two platforms operating in the Jupiter environment: the NASA-led Jupiter Europa Orbiter (JEO), and the ESA-led Jupiter Ganymede Orbiter (JGO). JEO and JGO will execute a choreographed exploration of the Jupiter System before settling into orbit around Europa and Ganymede, respectively. The EJSM mission architecture hence offers unique opportunities for synergistic and complementary observations that significantly enhance the overall science return of the mission. In this paper, we will first review new and unique science aspects of the Jupiter system that may benefit from different capabilities of RPW investigations onboard JGO and/or JEO: spectral and polarization information, mapping of radio sources, measurements of in situ plasma waves, currents, thermal noise, dust and nano-particle detection and characterization. We will then illustrate unique synergistic and complementary science opportunities offered by RPW investigations onboard JGO and/or JEO, both in terms of Satellite science and in terms of Magnetospheric Science.

  6. Freak waves in a plasma having Cairns particles

    Science.gov (United States)

    El-Tantawy, S. A.; El-Awady, E. I.; Schlickeiser, R.

    2015-12-01

    The probability of the existence of the ion-acoustic rogue waves in a plasma composed of warm ions and non-Maxwellian (nonthermal or Kappa) electrons is investigated in the framework of the modified Korteweg-de Vries (mKdV) equation. Using the reductive perturbation method, the Korteweg-de Vries (KdV) equation is derived. After numerical analysis, it is found that the present plasma system populated with nonthermal (Cairns) electrons leads to generation of compressive and rarefactive pulses, in contrast to the case of Kappa distribution. Thus, only for the nonthermal populated electrons, there is a critical value of the nonthermal parameter at which the coefficient of the nonlinear term of the KdV equation vanishes. In this case, we derived the modified KdV (mKdV) equation to describe the evolution of the system. To investigate the rogue waves propagation in our system, the mKdV equation should transfer to the nonlinear Schrödinger equation (NLSE). Our results provide a better understanding of observations in space plasmas which indicate the existence of nonthermal particles.

  7. Cross-polarization scattering from low-frequency waves in a tandem mirror plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kogi, Yuichiro; Mase, Atsushi; Bruskin, L.G.; Oyama, Naoyuki; Tokuzawa, Tokihiko; Itakura, Akiyosi; Hojo, Hitoshi; Tamano, Teruo [Tsukuba Univ., Ibaraki (Japan). Plasma Research Center

    1997-05-01

    Cross-polarization scattering (CPS) diagnostic was applied to the central-cell plasma of the GAMMA 10 tandem mirror in order to study electromagnetic plasma waves with frequencies of less than 200 kHz. In the CPS process, an incident ordinary (extraordinary) wave is converted to an extraordinary (ordinary) wave by magnetic fluctuations in a plasma. The converted wave propagates through the cutoff layer and reaches the opposite diagnostic port. The experimental data suggest that the power spectral density of the CPS signal satisfies the Bragg condition, while the reflectometer detects the waves near the cutoff layer where the wave number cannot be resolved. (author)

  8. Plasma waves observed by the IRM and UKS spacecraft during the AMPTE solar wind lithium releases - Overview

    Science.gov (United States)

    Haeusler, B.; Woolliscroft, L. J.; Anderson, R. R.; Gurnett, D. A.; Holzworth, R. H.

    1986-01-01

    The wave measurements from the Ion Release Module and the United Kingdom Satellite in the diamagnetic cavity, the transition region, and the upstream region are examined. Solar wind conditions during the releases on September 11 and 20, 1984 are described. The quasi-static electric field, wideband, high-frequency waves, and medium and VLF waves observations are analyzed. The data reveal that extremely low levels of wave activity are observed in the boundary between the diamagnetic cavity and external magnetic field, medium and VLF waves in the ion acoustic electrostatic cyclotron harmonic modes are detected in the transition region from the diamagnetic cavity to the solar wind, and decay in the magnetic field strength and density, and an increase in the quasi-static electric field is seen in the upstream edge of the transition region. The emissions observed are related to the different phases of the Li cloud development and different spatial regimes of the Li plasma-solar wind interaction.

  9. Decoherence of matter waves by thermal emission of radiation.

    Science.gov (United States)

    Hackermüller, Lucia; Hornberger, Klaus; Brezger, Björn; Zeilinger, Anton; Arndt, Markus

    2004-02-19

    Emergent quantum technologies have led to increasing interest in decoherence--the processes that limit the appearance of quantum effects and turn them into classical phenomena. One important cause of decoherence is the interaction of a quantum system with its environment, which 'entangles' the two and distributes the quantum coherence over so many degrees of freedom as to render it unobservable. Decoherence theory has been complemented by experiments using matter waves coupled to external photons or molecules, and by investigations using coherent photon states, trapped ions and electron interferometers. Large molecules are particularly suitable for the investigation of the quantum-classical transition because they can store much energy in numerous internal degrees of freedom; the internal energy can be converted into thermal radiation and thus induce decoherence. Here we report matter wave interferometer experiments in which C70 molecules lose their quantum behaviour by thermal emission of radiation. We find good quantitative agreement between our experimental observations and microscopic decoherence theory. Decoherence by emission of thermal radiation is a general mechanism that should be relevant to all macroscopic bodies.

  10. Plasma wave and third harmonic generation by a Gaussian electromagnetic beam in a collisionless magnetoplasma

    Energy Technology Data Exchange (ETDEWEB)

    Sodha, M.S.; Govind; Sharma, R.P. (Indian Inst. of Tech., New Delhi. Centre of Energy Studies)

    1981-05-01

    An investigation of the plasma wave and third harmonic generation by a Gaussian electromagnetic (em) beam, propagating in extraordinary mode in a collisionless hot magnetoplasma has been made. On account of the (VXB) force, a plasma wave at twice the pump wave frequency gets excited. The interaction of the plasma wave with the pump wave leads to third harmonic generation. By taking into account the self-focusing of the pump wave on account of non-uniform intensity distribution along the wave front, a modification is effected in the power of the plasma wave and the third harmonic em wave. The dependence of these phenomena on the strength of the static magnetic field has also been studied.

  11. VARIABLE GAMMA-RAY EMISSION FROM THE CRAB NEBULA: SHORT FLARES AND LONG 'WAVES'

    Energy Technology Data Exchange (ETDEWEB)

    Striani, E.; Tavani, M.; Vittorini, V.; Donnarumma, I.; Argan, A.; Cardillo, M.; Costa, E.; Del Monte, E.; Pacciani, L.; Piano, G.; Sabatini, S. [INAF/IASF-Roma, I-00133 Roma (Italy); Giuliani, A.; Mereghetti, S. [INAF/IASF-Milano, I-20133 Milano (Italy); Pucella, G.; Rapisarda, M. [ENEA Frascati, I-00044 Frascati (Roma) (Italy); Bulgarelli, A. [INAF/IASF-Bologna, I-40129 Bologna (Italy); Colafrancesco, S. [INAF - Osservatorio Astronomico di Roma via Frascati 33, I-00040 Monteporzio (Italy); Ferrari, A. [CIFS-Torino, I-10133 Torino (Italy); Pellizzoni, A. [INAF-Osservatorio Astronomico di Cagliari, localita' Poggio dei Pini, strada 54, I-09012 Capoterra (Italy); Pittori, C. [ASI Science Data Center, I-00044 Frascati (Roma) (Italy); and others

    2013-03-01

    Gamma-ray emission from the Crab Nebula has been recently shown to be unsteady. In this paper, we study the flux and spectral variability of the Crab above 100 MeV on different timescales ranging from days to weeks. In addition to the four main intense and day-long flares detected by AGILE and Fermi-LAT between 2007 September and 2012 September, we find evidence for week-long and less intense episodes of enhanced gamma-ray emission that we call 'waves'. Statistically significant 'waves' show timescales of 1-2 weeks, and can occur by themselves or in association with shorter flares. We present a refined flux and spectral analysis of the 2007 September-October gamma-ray enhancement episode detected by AGILE that shows both 'wave' and flaring behavior. We extend our analysis to the publicly available Fermi-LAT data set and show that several additional 'wave' episodes can be identified. We discuss the spectral properties of the 2007 September 'wave'/flare event and show that the physical properties of the 'waves' are intermediate between steady and flaring states. Plasma instabilities inducing 'waves' appear to involve spatial distances l {approx} 10{sup 16} cm and enhanced magnetic fields B {approx} (0.5-1) mG. Day-long flares are characterized by smaller distances and larger local magnetic fields. Typically, the deduced total energy associated with the 'wave' phenomenon (E{sub w} {approx} 10{sup 42} erg, where E{sub w} is the kinetic energy of the emitting particles) is comparable with that associated to the flares, and can reach a few percent of the total available pulsar spin-down energy. Most likely, flares and waves are the product of the same class of plasma instabilities that we show acting on different timescales and radiation intensities.

  12. Nonextensivity effect on radio-wave transmission in plasma sheath

    Science.gov (United States)

    Mousavi, A.; Esfandiari-Kalejahi, A.; Akbari-Moghanjoughi, M.

    2016-04-01

    In this paper, new theoretical findings on the application of magnetic field in effective transmission of electromagnetic (EM) waves through a plasma sheath around a hypersonic vehicle are reported. The results are obtained by assuming the plasma sheath to consist of nonextensive electrons and thermal ions. The expressions for the electric field and effective collision frequency are derived analytically in the framework of nonextensive statistics. Examination of the reflection, transmission, and absorption coefficients regarding the strength of the ambient magnetic field shows the significance of q-nonextensive parameter effect on these entities. For small values of the magnetic field, the transmission coefficient increases to unity only in the range of - 1 hypersonic flights.

  13. Physics of Collisionless Shocks Space Plasma Shock Waves

    CERN Document Server

    Balogh, André

    2013-01-01

    The present book provides a contemporary systematic treatment of shock waves in high-temperature collisionless plasmas as are encountered in near Earth space and in Astrophysics. It consists of two parts. Part I develops the complete theory of shocks in dilute hot plasmas under the assumption of absence of collisions among the charged particles when the interaction is mediated solely by the self-consistent electromagnetic fields. Such shocks are naturally magnetised implying that the magnetic field plays an important role in their evolution and dynamics. This part treats both subcritical shocks, which dissipate flow energy by generating anomalous resistance or viscosity, and supercritical shocks. The main emphasis is, however, on super-critical shocks where the anomalous dissipation is insufficient to retard the upstream flow. These shocks, depending on the direction of the upstream magnetic field, are distinguished as quasi-perpendicular and quasi-parallel shocks which exhibit different behaviours, reflecti...

  14. Internal wave emission from baroclinic jets: experimental results

    Science.gov (United States)

    Borcia, Ion D.; Rodda, Costanza; Harlander, Uwe

    2016-04-01

    Large-scale balanced flows can spontaneously radiate meso-scale inertia-gravity waves (IGWs) and are thus in fact unbalanced. While flow-dependent parameterizations for the radiation of IGWs from orographic and convective sources do exist, the situation is less developed for spontaneously emitted IGWs. Observations identify increased IGW activity in the vicinity of jet exit regions. A direct interpretation of those based on geostrophic adjustment might be tempting. However, directly applying this concept to the parameterization of spontaneous imbalance is difficult since the dynamics itself is continuously re-establishing an unbalanced flow which then sheds imbalances by GW radiation. Examining spontaneous IGW emission in the atmosphere and validating parameterization schemes confronts the scientist with particular challenges. Due to its extreme complexity, GW emission will always be embedded in the interaction of a multitude of interdependent processes, many of which are hardly detectable from analysis or campaign data. The benefits of repeated and more detailed measurements, while representing the only source of information about the real atmosphere, are limited by the non-repeatability of an atmospheric situation. The same event never occurs twice. This argues for complementary laboratory experiments, which can provide a more focused dialogue between experiment and theory. Indeed, life cycles are also examined in rotating-annulus laboratory experiments. Thus, these experiments might form a useful empirical benchmark for theoretical and modeling work that is also independent of any sort of subgrid model. In addition, the more direct correspondence between experimental and model data and the data reproducibility makes lab experiments a powerful testbed for parameterizations. Here we show first results from a small rotating annulus experiments and we will further present our new experimental facility to study wave emission from jets and fronts.

  15. Multi-instrument investigation of troposphere-ionosphere coupling through gravity waves and the role of gravity waves in the formation of equatorial plasma bubbles (EPBs)

    Science.gov (United States)

    Sivakandan, Mani; Patra, Amit; Sripathi, Samireddipelle; Thokuluwa, Ramkumar; Paulino, Igo; Taori, Alok; Kandula, Niranjan

    2016-07-01

    Equatorial plasma bubble (EPB) occurs in the equatorial ionosphere in pre-mid night (most of the time) as well as post-midnight (rarely) hours. The generation of EPBs by Rayleigh-Taylor Instability (RTI) due to seeding of gravity wave perturbation (polarization electric field) have well been explained theoretically by several authors but experimental evidence supporting this hypothesis is very limited. Using co-located observations from Gadanki (13.5oN, 79.2o E) using an all sky airglow imager and Gadanki Ionospheric Radar Interferometer (GIRI) and Ionosonde observations from Tirunelveli (8.7o N, 77.8o E), we investigate the role of gravity waves in the generation EPB during geomagnetic quiet conditions. To avoid any changes occurring in the background ionosphere owing to the large scale features (e.g., seasonal variation), we use four consecutive nights (03-06, February, 2014). Out of these four nights on two nights we have noted very strong plasma depletions in the OI 630 nm airglow emission and radar plumes. We analyse data to identify cases where, 1) EPBs occurred with large amplitudes of mesospheric gravity waves, 2) Occurrence of EPBs without large amplitudes of mesospheric gravity waves, and 3) identifiable mesospheric gravity waves without occurrence of EPBs. In order to calculate the mesospheric gravity wave parameter we used mesospheric OH airglow emission imager data, to identify their propagation to the E-region, we used E-region observations made using the MST radar which resembled the gravity wave signatures. Together with these, by using ray tracing techniques, we have identified the source region of the noted gravity wave events also. These results are discussed in detail in the present study.

  16. Polarizer design for millimeter-wave plasma diagnostics.

    Science.gov (United States)

    Leipold, F; Salewski, M; Jacobsen, A S; Jessen, M; Korsholm, S B; Michelsen, P K; Nielsen, S K; Stejner, M

    2013-08-01

    Radiation from magnetized plasmas is in general elliptically polarized. In order to convert the elliptical polarization to linear polarization, mirrors with grooved surfaces are currently employed in our collective Thomson scattering diagnostic at ASDEX Upgrade. If these mirrors can be substituted by birefringent windows, the microwave receivers can be designed to be more compact at lower cost. Sapphire windows (a-cut) as well as grooved high density polyethylene windows can serve this purpose. The sapphire window can be designed such that the calculated transmission of the wave energy is better than 99%, and that of the high density polyethylene can be better than 97%.

  17. ‘Magneto-elastic’ waves in an anisotropic magnetised plasma

    Science.gov (United States)

    Del Sarto, D.; Pegoraro, F.; Tenerani, A.

    2017-04-01

    The linear waves that propagate in a two fluid magnetised plasma allowing for a non-gyrotropic perturbed ion pressure tensor are investigated. For perpendicular propagation and perturbed fluid velocity a low frequency (magnetosonic) and a high frequency (ion Bernstein) branch are identified and discussed. For both branches a comparison is made with the results of a truncated Vlasov treatment. For the low frequency branch we show that a consistent expansion procedure allows us to recover the correct expression of the finite Larmor radius corrections to the magnetosonic dispersion relation.

  18. "Magneto-elastic" waves in an anisotropic magnetised plasma

    CERN Document Server

    Del Sarto, Daniele; Tenerani, Anna

    2015-01-01

    The linear waves that propagate in a two fluid magnetised plasma allowing for a non-gyrotropic perturbed ion pressure tensor are investigated. For perpendicular propagation and perturbed fluid velocity a low frequency (magnetosonic) and a high frequency (ion Bernstein) branch are identified and discussed. For both branches a comparison is made with the results of a kinetic Vlasov treatment. For the low frequency branch we show that a consistent expansion procedure allows us to recover the correct expression of the FLR corrections to the magnetosonic dispersion relation in agreement with Mikhailovskii and Smoliakov, Soviet Phys., JETP, 11, 1469 (1985).

  19. Wave Localization and Density Bunching in Pair Ion Plasmas

    CERN Document Server

    Mahajan, Swadesh M

    2008-01-01

    By investigating the nonlinear propagation of high intensity electromagnetic (EM) waves in a pair ion plasma, whose symmetry is broken via contamination by a small fraction of high mass immobile ions, it is shown that this new and interesting state of (laboratory created) matter is capable of supporting structures that strongly localize and bunch the EM radiation with density excess in the region of localization. Testing of this prediction in controlled laboratory experiments can lend credence, inter alia, to conjectures on structure formation (via the same mechanism) in the MEV era of the early universe.

  20. Broadband notch filter design for millimeter-wave plasma diagnostics

    DEFF Research Database (Denmark)

    Furtula, Vedran; Michelsen, Poul; Leipold, Frank;

    2010-01-01

    Notch filters are integrated in plasma diagnostic systems to protect millimeter-wave receivers from intensive stray radiation. Here we present a design of a notch filter with a center frequency of 140 GHz, a rejection bandwidth of ∼ 900 MHz, and a typical insertion loss below 2 dB in the passband...... of ±9 GHz. The design is based on a fundamental rectangular waveguide with eight cylindrical cavities coupled by T-junction apertures formed as thin slits. Parameters that affect the notch performance such as physical lengths and conductor materials are discussed. The excited resonance mode...

  1. Plasma Emission Profile Recreation using Soft X-Ray Tomography

    Science.gov (United States)

    Page, J. W.; Mauel, M. E.; Levesque, J. P.

    2015-11-01

    With sufficient views from multiple diode arrays, soft X-ray tomography is an invaluable plasma diagnostic because it is a non-perturbing method to reconstruct the emission within the interior of the plasma. In preparation for the installation of new SXR arrays in HBT-EP, we compute high-resolution tomographic reconstructions of discharges having kink-like structures that rotate nearly rigidly. By assuming a uniform angular mapping from the kink mode rotation, Δϕ ~ ωΔ t, a temporal sequence from a single 16-diode fan array represents as many as 16 x 100 independent views. We follow the procedure described by Wang and Granetz and use Bessel basis functions to take the inverse Radon transform. This transform is fit to our data using a least-squares method to estimate the internal SXR emissivity as a sum of polar functions. By varying different parameters of the transformation, we optimize the quality of our recreation of the emission profile and quantify how the reconstruction changes with the azimuthal order of the transform. Supported by U.S. DOE Grant DE-FG02-86ER53222.

  2. Plasma and wave phenomena induced by neutral gas releases in the solar wind

    Directory of Open Access Journals (Sweden)

    H. Laakso

    Full Text Available We investigate plasma and wave disturbances generated by nitrogen (N2 gas releases from the cooling system of an IR-camera on board the Vega 1 and Vega 2 spacecraft, during their flybys of comet Halley in March 1986. N2 molecules are ionized by solar UV radiation at a rate of ~ 7 · 10-7 s-1 and give rise to a plasma cloud expanding around the spacecraft. Strong disturbances due to the interaction of the solar wind with the N+2 ion cloud are observed with a plasma and wave experiment (APV-V instrument. Three gas releases are accompanied by increases in cold electron density and simultaneous decreases of the spacecraft potential; this study shows that the spacecraft potential can be monitored with a reference sensor mounted on a short boom. The comparison between the model and observations suggests that the gas expands as an exhaust plume, and approximately only 1% of the ions can escape the beam within the first meters. The releases are also associated with significant increases in wave electric field emission (8 Hz–300 kHz; this phenomenon lasts for more than one hour after the end of the release, which is most likely due to the temporary contamination of the spacecraft surface by nitrogen gas. DC electric fields associated with the events are complex but interesting. No magnetic field perturbations are detected, suggesting that no significant diamagnetic effect (i.e. magnetic cavity is associated with these events.

    Key words. Ionosphere (planetary ionosphere – Space plasma physics (active perturbation experiments; instruments and techniques

  3. Nonlinear instability and chaos in plasma wave-wave interactions. II. Numerical methods and results

    Energy Technology Data Exchange (ETDEWEB)

    Kueny, C.S.; Morrison, P.J.

    1995-05-01

    In Part I of this work and Physics of Plasmas, June 1995, the behavior of linearly stable, integrable systems of waves in a simple plasma model was described using a Hamiltonian formulation. It was shown that explosive instability arises from nonlinear coupling between modes of positive and negative energy, with well-defined threshold amplitudes depending on the physical parameters. In this concluding paper, the nonintegrable case is treated numerically. Several sets of waves are considered, comprising systems of two and three degrees of freedom. The time evolution is modelled with an explicit symplectic integration algorithm derived using Lie algebraic methods. When initial wave amplitudes are large enough to support two-wave decay interactions, strongly chaotic motion destroys the separatrix bounding the stable region for explosive triplets. Phase space orbits then experience diffusive growth to amplitudes that are sufficient for explosive instability, thus effectively reducing the threshold amplitude. For initial amplitudes too small to drive decay instability, small perturbations might still grow to arbitrary size via Arnold diffusion. Numerical experiments do not show diffusion in this case, although the actual diffusion rate is probably underestimated due to the simplicity of the model.

  4. Mechanism of laser-induced plasma shock wave evolution in air

    Institute of Scientific and Technical Information of China (English)

    Zhao Rui; Liang Zhong-Cheng; Han Bing; Zhang Hong-Chao; Xu Rong-Qing; Lu Jian; Ni Xiao-Wu

    2009-01-01

    A theoretical model is proposed to describe the mechanism of laser-induced plasma shock wave evolution in air. To verify the validity of the theoretical model, an optical beam deflection technique is employed to track the plasma shock wave evolution process. The theoretical model and the experimental signals are found to be in good agreement with each other. It is shown that the laser-induced plasma shock wave undergoes formation, increase and decay processes; the increase and the decay processes of the laser-induced plasma shock wave result from the overlapping of the compression wave and the rarefaction wave, respectively. In addition, the laser-induced plasma shock wave speed and pressure distributions, both a function of distance, are presented.

  5. Structured waves near the plasma frequency observed in three auroral rocket flights

    Directory of Open Access Journals (Sweden)

    M. Samara

    2006-11-01

    Full Text Available We present observations of waves at and just above the plasma frequency (fpe from three high frequency electric field experiments on three recent rockets launched to altitudes of 300–900 km in active aurora. The predominant observed HF waves just above fpe are narrowband, short-lived emissions with amplitudes ranging from <1 mV/m to 20 mV/m, often associated with structured electron density. The nature of these HF waves, as determined from frequency-time spectrograms, is highly variable: in some cases, the frequency decreases monotonically with time as in the "HF-chirps" previously reported (McAdams and LaBelle, 1999, but in other cases rising frequencies are observed, or features which alternately rise and fall in frequency. They exhibit two timescales of amplitude variation: a short timescale, typically 50–100 ms, associated with individual discrete features, and a longer timescale associated with the general decrease in the amplitudes of the emissions as the rocket moves away from where the condition f~fpe holds. The latter timescale ranges from 0.6 to 6.0 s, corresponding to distances of 2–7 km, assuming the phenomenon to be stationary and using the rocket velocity to convert time to distance.

  6. Features of electromagnetic waves in a complex plasma due to surface plasmon resonances on macroparticles

    CERN Document Server

    Vladimirov, S V

    2015-01-01

    The dielectric properties of complex plasma containing either metal or dielectric spherical inclusions (macroparticles, dust) are investigated. We focus on surface plasmon resonances on the macroparticle surfaces and their effect on electromagnetic wave propagation. It is demonstrated that the presence of surface plasmon oscillations significantly modifies plasma electromagnetic properties by resonances and cutoffs in the effective permittivity. This leads to related branches of electromagnetic waves and to the wave band gaps. The results are discussed in the context of dusty plasma experiments.

  7. Visualizing a Dusty Plasma Shock Wave via Interacting Multiple-Model Mode Probabilities

    OpenAIRE

    Oxtoby, Neil P.; Ralph, Jason F.; Durniak, Céline; Samsonov, Dmitry

    2011-01-01

    Particles in a dusty plasma crystal disturbed by a shock wave are tracked using a three-mode interacting multiple model approach. Color-coded mode probabilities are used to visualize the shock wave propagation through the crystal.

  8. A compact plasma focus device and its neutron emission

    Institute of Scientific and Technical Information of China (English)

    王新新; 韩旻; 王志文; 刘坤

    1999-01-01

    A 2.2-kJ compact plasma focus device was developed and its characteristics of neutron emission were investigated. A maximum neutron yield of (3.1 ± 1.5) × 10~7 was obtained at 15 hPa deuterium filling pressure. It was found that the neutron yield Y_n is strongly correlated with the amplitude of the pinch dip in di/dt waveform. The time resolved measurement of the neutron pulse indicated that both the hard X-rays and the neutrons are emitted from plasma focus at the same instant and the width of neutron pulse (FWHM) changes slightly from 50 to 53 ns. The pinch time t_p varies from 1.5 to 16.5 ns and it is usually the case that the shorter t_p, the higher the neutron yield. It was also found that the squirrel cage cathode is better than the tubular cathode.

  9. X-ray emission of exotic ions in dense plasmas

    Science.gov (United States)

    Rosmej, F. B.; Khaghani, D.; Dozières, M.; Dachicourt, R.; Šmíd, M.; Renner, O.

    2017-03-01

    Hollow ion X-ray emission has been observed in experiments studying interaction of heavy ion beams with solids and their occurrence has been ascribed to charge exchange processes occurring when highly charged ions interact with a metal surface. In high temperature high-density plasmas, like, e.g., high intensity laser produced plasmas or high current Z-pinches, numerous researchers have reported about "exotic" X-ray transitions of hollow ions: K0LX →K1LX-1+hνhollow. Although atomic structure calculations seem to confirm that measured line positions correspond to transitions in hollow ions, line identification is difficult and the observed high intensity remains a mystery (by orders of magnitude) up to present days.

  10. Surface Emission of Quark Gluon Plasma at RHIC and LHC

    Institute of Scientific and Technical Information of China (English)

    XIANG Wen-Chang; WAN Ren-Zhuo; ZHOU Dai-Cui

    2008-01-01

    Within the framework of a factorization model, we study the behaviour of nuclear modification factor in Au-Au collisions at RHIC and Pb-Pb collisions at LHC. We find that the nuclear modification factor is inversely proportional to the radius of the quark-gluon plasma and is dominated by the surface emission of hard jets. We predict the nuclear modification factor RLHCAA~0.15 in central Pb-Pb collisions at LHC. The study shows that the factorization model can be used to describe the centrality dependence of nuclear modification factor of the high transverse momentum particles produced in heavy ion collisions at both RHIC and LHC.

  11. Theoretical study of nonlinear waves and shock-like phenomena in hot plasmas

    Science.gov (United States)

    Fried, B. D.; Banos, A., Jr.; Kennel, C. F.

    1973-01-01

    Summaries are presented of research in basic plasma physics. Nonlinear waves and shock-like phenomena were studied which are pertinent to space physics applications, and include specific problems of magnetospheric and solar wind plasma physics.

  12. Shukla-Spatschek diffusion effects on surface plasma waves in astrophysical turbulent plasmas

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-02-01

    The effects of Shukla-Spatschek turbulent diffusion on a temporal mode of surface waves propagating at the interface of an astrophysical turbulent plasma are investigated. The damping rates for high and low modes of surface wave are kinetically derived by employing the Vlasov-Poisson equation and the specular reflection boundary condition. We found that the diffusion caused by the fluctuating electric fields leads to damping for both high and low modes of surface waves. The high-mode damping is enhanced with an increase of the wavenumber and the diffusion coefficient, but suppressed by an increase of electron thermal energy. By contrast, the low-mode damping is suppressed as the wavenumber and the thermal energy increase although it is enhanced as the diffusion increases. The variation of the damping rate due to the Shukla-Spatschek turbulent diffusion is also discussed.

  13. Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse

    Energy Technology Data Exchange (ETDEWEB)

    Grishkov, V. E.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2017-03-15

    Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse is analyzed within the kinetic approach. It is shown that the most efficient source of plasma waves is the nonlinear current arising due to the gradient of the energy density of the high-frequency field. Generation of plasma waves by the drag current is usually less efficient but not negligibly small at relatively high frequencies of electron–ion collisions. The influence of electron collisions on the excitation of plasma waves by pulses of different duration is described quantitatively.

  14. Poloidal rotation induced by injecting lower hybrid waves in tokamak plasma edge

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The poloidal rotation of the magnetized edge plasma in tokamak driven by theponderomotive force which is generated by injecting lower hybrid wave(LHW) electric field hasbeen studied. The LHW is launched from a waveguide in the plasma edge, and by Brambilla’sgrill theory, analytic expressions for the wave electric field in the slab model of an inhomogeneouscold plasma have been derived. It is shown that a strong wave electric field will be generated inthe plasma edge by injecting LH wave of the power in MW magnitude, and this electric field willinduce a poloidal rotation with a sheared poloidal velocity.PACS: 52.55.Fa

  15. Measurement of the Electron Bernstein Wave Emission with One of the Power Transmission Lines for ECH in LHD%Measurement of the Electron Bernstein Wave Emission with One of the Power Transmission Lines for ECH in LHD

    Institute of Scientific and Technical Information of China (English)

    Hiroe IGAMI; Hiroshi IDEI; Shin KUBO; Yasuo YOSHIMURA; Takashi SHIMOZUMA; Hiromi TAKAHASHI

    2011-01-01

    Possibility of the measurement of radiated waves derived from the thermally emitted electron Bernstein wave (EBW) is numerically investigated based on the assumption of the super dense core (SDC) plasma generated in LHD. EBW that is thermally emitted in the electron cyclotron resonance (ECR) layer may couple with the electromagnetic wave and be emitted to the vacuum via the EBW-extraordinary-ordinary (B-X-O) mode conversion process. We consider the use of one of the transmission lines for electron cyclotron heating (ECH) in LHD as a receiving system of the emission. It is derived that the waves in the fundamental cyclotron frequency range are emitted as the EBW near their upper hybrid resonance (UHR) layer outside the last close flux surface (LCFS). On the other hand, waves in the second harmonics cyclotron frequency range are emitted in the core region. It means that successful measurement of waves of the second harmonic frequency range emitted from extremely high dense core plasma with setting an aim angle for receiving indicates a possibility of the second harmonic ECH by EBW in the core region with setting the same aim angle and the same polarization for launching.

  16. Quasi-periodic behavior of ion acoustic solitary waves in electron-ion quantum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, Biswajit [Department of Mathematics, West Bengal State University Barasat, Kolkata-700126 (India); Poria, Swarup [Department of Applied Mathematics, University of Calcutta Kolkata-700009 (India); Narayan Ghosh, Uday [Department of Mathematics, Siksha Bhavana, Visva Bharati University Santiniketan (India); Roychoudhury, Rajkumar [Physics and Applied Mathematics Unit, Indian Statistical Institute Kolkata-700108 (India)

    2012-05-15

    The ion acoustic solitary waves are investigated in an unmagnetized electron-ion quantum plasmas. The one dimensional quantum hydrodynamic model is used to study small as well as arbitrary amplitude ion acoustic waves in quantum plasmas. It is shown that ion temperature plays a critical role in the dynamics of quantum electron ion plasma, especially for arbitrary amplitude nonlinear waves. In the small amplitude region Korteweg-de Vries equation describes the solitonic nature of the waves. However, for arbitrary amplitude waves, in the fully nonlinear regime, the system exhibits possible existence of quasi-periodic behavior for small values of ion temperature.

  17. 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

  18. Propagation of Surface Wave Along a Thin Plasma Column and Its Radiation Pattern

    Institute of Scientific and Technical Information of China (English)

    WANG Zhijiang; ZHAO Guowei; XU Yuemin; LIANG Zhiwei; XU Jie

    2007-01-01

    Propagation of the surface waves along a two-dimensional plasma column and the far-field radiation patterns are studied in thin column approximation. Wave phase and attenuation coefficients are calculated for various plasma parameters. The radiation patterns are shown. Results show that the radiation patterns are controllable by flexibly changing the plasma length and other parameters in comparison to the metal monopole antenna. It is meaningful and instructional for the optimization of the plasma antenna design.

  19. Electron Bernstein waves emission in the TJ--II Stellarator

    CERN Document Server

    García-Regaña, J M; Castejón, F; Caughman, J B O; Tereshchenko, M; Ros, A; Rasmussen, D A; Wilgen, J B

    2010-01-01

    Taking advantage of the electron Bernstein waves heating (EBWH) system of the TJ--II stellarator, an electron Bernstein emission (EBE) diagnostic was installed. Its purpose is to investigate the B--X--O radiation properties in the zone where optimum theoretical EBW coupling is predicted. An internal movable mirror shared by both systems allows us to collect the EBE radiation along the same line of sight that is used for EBW heating. The theoretical EBE has been calculated for different orientations of the internal mirror using the TRUBA code as ray tracer. A comparison with experimental data obtained in NBI discharges is carried out. The results provide a valuable information regarding the experimental O--X mode conversion window expected in the EBW heating experiments. Furthermore, the characterization of the radiation polarization shows evidence of the underlying B--X--O conversion process.

  20. The one loop gluon emission light cone wave function

    CERN Document Server

    Lappi, Tuomas

    2016-01-01

    Light cone perturbation theory has become an essential tool to calculate cross sections for various small-$x$ dilute-dense processes such as deep inelastic scattering and forward proton-proton and proton-nucleus collisions. Here we set out to do one loop calculations in an explicit helicity basis in the four dimensional helicity scheme. As a first process we calculate light cone wave function for one gluon emission to one-loop order in Hamiltonian perturbation theory on the light front. We regulate ultraviolet divergences with transverse dimensional regularization and soft divergences with using a cut-off on longitudinal momentum. We show that when all the renormalization constants are combined, the ultraviolet divergences can be absorbed into the standard QCD running coupling constant, and give an explicit expression for the remaining finite part.

  1. Empirical Emission Functions for LPM Suppression of Photon Emission from Quark-Gluon Plasma

    CERN Document Server

    Sastry, S

    2003-01-01

    The LPM suppression of photon emission rates from the quark gluon plasma have been studied at different physical conditions of the plasma given by temperature and chemical potentials.The integral equation for the transverse vector function (f(p_t)) consisting of multiple scattering effects is solved for the parameter set {p,k,kappa,T}, for bremsstrahlung and AWS processes. The peak positions of these distributions depend only on the dynamical variable x=(T/kappa)|1/p-1/(p+k)|. Integration over these distributions multiplied by x^2 factor also depends on this variable x,leading to a unique global emission function g(x) for all parameters. Empirical fits to this dimensionless emission function, g(x), are obtained. The photon emission rate calculations with LPM suppression effects reduce to one dimensional integrals involving folding over the empirical g(x) function with appropriate distribution functions and the kinematic factors. Using this approach, the suppression factors for both bremsstrahlung and AWS have...

  2. ISIS Topside-Sounder Plasma-Wave Investigations as Guides to Desired Virtual Wave Observatory (VWO) Data Search Capabilities

    Science.gov (United States)

    Benson, Robert F.; Fung, Shing F.

    2008-01-01

    Many plasma-wave phenomena, observed by space-borne radio sounders, cannot be properly explained in terms of wave propagation in a cold plasma consisting of mobile electrons and infinitely massive positive ions. These phenomena include signals known as plasma resonances. The principal resonances at the harmonics of the electron cyclotron frequency, the plasma frequency, and the upper-hybrid frequency are well explained by the warm-plasma propagation of sounder-generated electrostatic waves, Other resonances have been attributed to sounder-stimulated plasma instability and non-linear effects, eigenmodes of cylindrical electromagnetic plasma oscillations, and plasma memory processes. Data from the topside sounders of the International Satellites for Ionospheric Studies (ISIS) program played a major role in these interpretations. A data transformation and preservation effort at the Goddard Space Flight Center has produced digital ISIS topside ionograms and a metadata search program that has enabled some recent discoveries pertaining to the physics of these plasma resonances. For example, data records were obtained that enabled the long-standing question (several decades) of the origin of the plasma resonance at the fundamental electron cyclotron frequency to be explained [Muldrew, Radio Sci., 2006]. These data-search capabilities, and the science enabled by them, will be presented as a guide to desired data search capabilities to be included in the Virtual Wave Observatory (VWO).

  3. Bohm potential effect on the propagation of electrostatic surface wave in semi-bounded quantum plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myoung-Jae [Department of Physics, Hanyang University, Seoul 04763 (Korea, Republic of); Research Institute for Natural Sciences, Hanyang University, Seoul 04763 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588 (Korea, Republic of); Department of Electrical and Computer Engineering, MC 0407, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0407 (United States)

    2017-02-12

    High frequency electrostatic wave propagation in a dense and semi-bounded electron quantum plasma is investigated with consideration of the Bohm potential. The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. We found that the quantum effect enhances the frequency of the wave especially in the high wave number regime. However, the frequency of surface wave is found to be always lower than that of the bulk wave for the same quantum wave number. The group velocity of the surface wave for various quantum wave number is also obtained. - Highlights: • High frequency electrostatic wave propagation is investigated in a dense semi-bounded quantum plasma. • The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. • The quantum effect enhances the frequency of the wave especially in the high wave number regime. • The frequency of surface wave is found to be always lower than that of the bulk wave. • The group velocity of the surface wave for various quantum wave number is also obtained.

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

    Science.gov (United States)

    Abbott, B.; Abbott, R.; 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. A.; Bayer, K.; Belczynski, 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.; Butler, W. E.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Camp, J. B.; Cannizzo, J.; Cannon, K.; Cantley, C. A.; Cao, J.; Cardenas, L.; Carter, K.; Casey, M. M.; Castaldi, G.; Cepeda, C.; Chalkey, E.; Charlton, P.; Chatterji, S.; Chelkowski, S.; Chen, Y.; Chiadini, F.; Chin, D.; Chin, E.; Chow, J.; Christensen, N.; Clark, J.; Cochrane, P.; Cokelaer, T.; Colacino, C. N.; Coldwell, R.; Conte, R.; Cook, D.; Corbitt, T.; Coward, D.; Coyne, D.; Creighton, J. D. E.; Creighton, T. D.; Croce, R. P.; Crooks, D. R. M.; Cruise, A. M.; Cumming, A.; Dalrymple, J.; D'Ambrosio, E.; Danzmann, K.; Davies, G.; Debra, D.; Degallaix, J.; Degree, M.; Demma, T.; Dergachev, V.; Desai, S.; Desalvo, R.; Dhurandhar, S.; Díaz, M.; Dickson, J.; di Credico, A.; Diederichs, G.; Dietz, A.; Doomes, E. E.; Drever, R. W. P.; Dumas, J.-C.; Dupuis, R. J.; Dwyer, J. G.; 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.; Fricke, T.; Fritschel, P.; Frolov, V. V.; Fyffe, M.; Galdi, V.; Ganezer, K. S.; 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.; Grunewald, S.; Guenther, M.; Gustafson, R.; 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.; Howell, E.; Hoyland, D.; Huttner, S. H.; Ingram, D.; Innerhofer, E.; Ito, M.; Itoh, Y.; Ivanov, A.; Jackrel, D.; Johnson, B.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; 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.; Kwee, P.; Lam, P. K.; Landry, M.; Lantz, B.; Lazzarini, A.; Lee, B.; Lei, M.; Leiner, J.; Leonhardt, V.; Leonor, I.; Libbrecht, K.; Lindquist, P.; Lockerbie, N. A.; Longo, M.; Lormand, M.; Lubiński, M.; Lück, H.; Machenschalk, B.; Macinnis, M.; Mageswaran, M.; Mailand, K.; Malec, M.; Mandic, V.; Marano, S.; Márka, 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.; McNabb, J. W. C.; McWilliams, S.; Meier, T.; Melissinos, A.; 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.; Mowlowry, C.; Moylan, A.; Mudge, D.; Mueller, G.; Mukherjee, S.; Müller-Ebhardt, H.; Munch, J.; Murray, P.; Myers, E.; Myers, J.; Nash, T.; Newton, G.; Nishizawa, A.; Nocera, F.; Numata, K.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pan, Y.; Papa, M. A.; Parameshwaraiah, V.; Parameswariah, C.; 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.; Rawlins, K.; Ray-Majumder, S.; Re, V.; Regimbau, T.; 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.; Rodriguez, A.; Rogan, A. M.; Rollins, J.; Romano, J. D.; Romie, J.; Route, R.; Rowan, S.; Rüdiger, A.; Ruet, L.; Russell, P.; Ryan, K.; Sakata, S.; Samidi, M.; de La Jordana, L. Sancho; Sandberg, V.; Sanders, G. H.; Sannibale, V.; Saraf, S.; Sarin, P.; Sathyaprakash, B. S.; Sato, S.; Saulson, P. R.; Savage, R.; Savov, P.; Sazonov, A.; 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. J. J.; 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.; Tarallo, M.; Taylor, R.; 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.; Ungarelli, C.; Urbanek, K.; Vahlbruch, H.; Vallisneri, M.; van den Broeck, C.; van Putten, M.; 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.; Webber, D.; Weidner, A.; Weinert, M.; Weinstein, A.; Weiss, R.; Wen, S.; Wette, K.; Whelan, J. T.; Whitbeck, D. M.; Whitcomb, S. E.; Whiting, B. F.; Wiley, S.; 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.; Zur Mühlen, H.; Zweizig, J.; Kramer, M.; Lyne, A. G.

    2007-08-01

    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 GEO 600 gravitational wave detectors. The data from both runs have been combined coherently to maximize 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 2.6×10-25 for PSR J1603-7202, and the equatorial ellipticity of PSR J2124 3358 is less than 10-6. Furthermore, our strain upper limit for the Crab pulsar is only 2.2 times greater than the fiducial spin-down limit.

  5. Detecting gravitational wave emission from the known accreting neutron stars

    CERN Document Server

    Watts, Anna; Bildsten, Lars; Schutz, Bernard

    2008-01-01

    Detection of gravitational waves from accreting neutron stars (NSs) in our galaxy, due to ellipticity or internal oscillation, would be a breakthrough in our understanding of compact objects and explain the absence of NSs rotating near the break-up limit. Direct detection, however, poses a formidable challenge. Using the current data available on the properties of the accreting NSs in Low Mass X-Ray Binaries (LMXBs), we quantify the detectability for the known accreting NSs, considering various emission scenarios and taking into account the negative impact of parameter uncertainty on the data analysis process. Only a few of the persistently bright NSs accreting at rates near the Eddington limit are detectable by Advanced LIGO if they are emitting gravitational waves at a rate matching the torque from accretion. A larger fraction of the known population is detectable if the spin and orbital parameters are known in advance, especially with the narrow-band Advanced LIGO. We identify the most promising targets, a...

  6. Generation and detection of whistler wave induced space plasma turbulence at Gakona, Alaska

    Science.gov (United States)

    Rooker, L. A.; Lee, M. C.; Pradipta, R.; Watkins, B. J.

    2013-07-01

    We report on high-frequency wave injection experiments using the beat wave technique to study the generation of very-low-frequency (VLF) whistler waves in the ionosphere above Gakona, Alaska. This work is aimed at investigating whistler wave interactions with ionospheric plasmas and radiation belts. The beat wave technique involves injecting two X-mode waves at a difference frequency in the VLF range using the High-frequency Active Auroral Research Program (HAARP) heating facility. A sequence of beat wave-generated whistler waves at 2, 6.5, 7.5, 8.5, 9.5, 11.5, 15.5, 22.5, 28.5 and 40.5 kHz were detected in our 2011 experiments. We present Modular Ultra-high-frequency Ionospheric Radar (MUIR) (446 MHz) measurements of ion lines as the primary diagnosis of ionospheric plasma effects caused by beat wave-generated whistler waves. A magnetometer and digisonde were used to monitor the background ionospheric plasma conditions throughout the experiments. Our theoretical and data analyses show that VLF whistler waves can effectively interact with ionospheric plasmas via two different four-wave interaction processes leading to energization of electrons and ions. These preliminary results support our Arecibo experiments to study NAU-launched 40.75 kHz whistler wave interactions with space plasmas.

  7. Numerical evaluation of external magnetic effect on electromagnetic wave transmission through reentry plasma layer

    Science.gov (United States)

    Zhao, Qing; Bo, Yong; Lei, Mingda; Liu, Shuzhang; Liu, Ying; Liu, Jianwei; Zhao, Yizhe

    2016-11-01

    Numerical study of electromagnetic (EM) wave transmission through the magnetized plasma layer is presented in this paper. The plasma parameters are derived from computational fluid dynamics simulation of the flow field around a blunt body flying at supersonic speed and serve as the background plasma condition in the numerical modeling for EM wave transmission. The EM wave is generated by our newly designed coaxial feed GPS patch antenna. The external magnetic field is applied and assumed to vary linearly as a function of wall distance. The effects of the external applied magnetic field and the plasma parameters on wave transmission are studied, and the results show that EM wave propagation in the non-uniformly magnetized plasma is a matter of impedance matching, and the EM wave transmission can be adjusted only when the proper strength of the magnetic field is applied.

  8. Comment on "Propagation of surface waves on a semi-bounded quantum magnetized collisional plasma" [Phys. Plasmas 20, 122106 (2013)

    Science.gov (United States)

    Moradi, Afshin

    2016-04-01

    In a recent article [Niknam et al., Phys. Plasmas 20, 122106 (2013)], Niknam et al. investigated the propagation of TM surface waves on a semi-bounded quantum magnetized collisional plasma in the Faraday configuration (in this case, the magnetic field is parallel to the both of the plasma surface and direction of propagation). Here, we present a fresh look at the problem and show that TM surface waves cannot propagate on surface of the present system. We find in the Faraday configuration the surface waves acquire both TM and TE components due to the cyclotron motion of electrons. Therefore, the main result of the work by Niknam et al. is incorrect.

  9. Oscillating two-stream instability of laser wakefield-driven plasma wave

    Indian Academy of Sciences (India)

    Nafis Ahmad; V K Tripathi; Moiz Ahmad; M Rafat

    2016-01-01

    The laser wakefield-driven plasma wave in a low-density plasma is seen to be susceptible to the oscillating two-stream instability (OTSI). The plasma wave couples to two short wavelength plasma wave sidebands. The pump plasma wave and sidebands exert a ponderomotive force on the electrons driving a low-frequency quasimode. The electron density perturbation associated with this mode couples with the pump-driven electron oscillatory velocity to produce nonlinear currents driving the sidebands. At large pump amplitude, the instability grows faster than the ion plasma frequency and ions do not play a significant role. The growth rate of the quasimode, at large pump amplitude scales faster than linear. The growth rate is maximum for an optimum wave number of the quasimode and also increases with pump amplitude. Nonlocal effects, however reduce the growth rate by about half.

  10. Space and Astrophysical Plasmas : Sun–Earth connection: Boundary layer waves and auroras

    Indian Academy of Sciences (India)

    G S Lakhina; B T Tsurutani; J K Arballo; C Galvan

    2000-11-01

    Boundary layers are the sites where energy and momentum are exchanged between two distinct plasmas. Boundary layers occurring in space plasmas can support a wide spectrum of plasma waves spanning a frequency range of a few mHz to 100 kHz and beyond. The main characteristics of the broadband plasma waves (with frequencies > 1 Hz) observed in the magnetopause, polar cap, and plasma sheet boundary layers are described. The rapid pitch angle scattering of energetic particles via cyclotron resonant interactions with the waves can provide sufficient precipitated energy flux to the ionosphere to create the diffused auroral oval. The broadband plasma waves may also play an important role in the processes of local heating/acceleration of the boundary layer plasma.

  11. Simulations of electromagnetic emissions produced in a thin plasma by a continuously injected electron beam

    CERN Document Server

    Annenkov, V V; Volchok, E P

    2015-01-01

    In this paper, electromagnetic emissions produced in a thin beam-plasma system are studied using two-dimensional particle-in-cell simulations. For the first time, the problem of emission generation in such a system is considered in the realistic formulation allowing for the continuous injection of a relativistic electron beam through the plasma boundary. Specific attention is given to the thin plasma case in which the transverse plasma size is comparable to the typical wavelength of beam-driven oscillations. Such a case is often implemented in laboratory beam-plasma experiments and has a number of peculiarities. Emission from a thin plasma does not require intermediate generation of electromagnetic plasma eigenmodes, as in the infinite case, and is more similar to the regular antenna radiation. In this work, we determine how efficiently the fundamental and second harmonic emissions can be generated in previously modulated and initially homogeneous plasmas.

  12. Simulations of electromagnetic emissions produced in a thin plasma by a continuously injected electron beam

    Science.gov (United States)

    Annenkov, V. V.; Timofeev, I. V.; Volchok, E. P.

    2016-05-01

    In this paper, electromagnetic emissions produced in a thin beam-plasma system are studied using two-dimensional particle-in-cell simulations. For the first time, the problem of emission generation in such a system is considered in a realistic formulation allowing for the continuous injection of a relativistic electron beam through a plasma boundary. Specific attention is given to the thin plasma case in which the transverse plasma size is comparable to the typical wavelength of beam-driven oscillations. Such a case is often implemented in laboratory beam-plasma experiments and has a number of peculiarities. Emission from a thin plasma does not require intermediate generation of the electromagnetic plasma eigenmodes, as in an infinite case, and is more similar to the regular antenna radiation. In this work, we determine how efficiently the fundamental and the second harmonic emissions can be generated in previously modulated and initially homogeneous plasmas.

  13. Plasma-induced field emission study of carbon nanotube cathode

    Directory of Open Access Journals (Sweden)

    Yi Shen

    2011-10-01

    Full Text Available An investigation on the plasma-induced field emission (PFE properties of a large area carbon nanotube (CNT cathode on a 2 MeV linear induction accelerator injector is presented. Experimental results show that the cathode is able to emit intense electron beams. Intense electron beams of 14.9–127.8  A/cm^{2} are obtained from the cathode. The CNT cathode desorbs gases from the CNTs during the PFE process. The fast cathode plasma expansion affects the diode perveance. The amount of outgassing is estimated to be 0.06–0.49  Pa·L, and the ratio of outgassing and electron are roughly calculated to be within the range of 170–350 atoms per electron. The effect of the outgassing is analyzed, and the outgassing mass spectrum of the CNT cathode has been studied during the PFE. There is a significant desorption of CO_{2}, N_{2}(CO, and H_{2} gases, which plays an important role during the PFE process. All the experiments demonstrate that the outgassing plays an important role in the formation of the cathode plasma. Moreover, the characteristic turn-on time of the CNT cathode was measured to be 39 ns.

  14. Optical emission spectroscopy of argon and hydrogen-containing plasmas

    Science.gov (United States)

    Siepa, Sarah; Danko, Stephan; Tsankov, Tsanko V.; Mussenbrock, Thomas; Czarnetzki, Uwe

    2015-09-01

    Optical emission spectroscopy (OES) on neutral argon is applied to investigate argon, hydrogen and hydrogen-silane plasmas. The spectra are analyzed using an extensive collisional-radiative model (CRM), from which the electron density and the electron temperature (or mean energy) can be calculated. The CRM also yields insight into the importance of different excited species and kinetic processes. The OES measurements are performed on pure argon plasmas at intermediate pressure. Besides, hydrogen and hydrogen-silane plasmas are investigated using argon as a trace gas. Especially for the gas mixture discharges, CRMs for low and high pressure differ substantially. The commonly used line-ratio technique is found to lose its sensitivity for gas mixture discharges at higher pressure. A solution using absolutely calibrated line intensities is proposed. The effect of radiation trapping and the shape of the electron energy distribution function on the results are discussed in detail, as they have been found to significantly influence the results. This work was supported by the Ruhr University Research School PLUS, funded by Germany's Excellence Initiative [DFG GSC 98/3].

  15. The ''phase velocity'' of nonlinear plasma waves in the laser beat-wave accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Spence, W.L.

    1985-04-01

    A calculational scheme for beat-wave accelerators is introduced that includes all orders in velocity and in plasma density, and additionally accounts for the influence of plasma nonlinearities on the wave's phase velocity. The main assumption is that the laser frequencies are very large compared to the plasma frequency - under which it is possible to sum up all orders of forward Raman scattering. It is found that the nonlinear plasma wave does not have simply a single phase velocity, but that the beat-wave which drives it is usefully described by a non-local ''effective phase velocity'' function. A time-space domain approach is followed. (LEW)

  16. Plasma simulations of emission line regions in high energy environments

    Science.gov (United States)

    Richardson, Chris T.

    This dissertation focuses on understanding two different, but in each case extreme, astrophysical environments: the Crab Nebula and emission line galaxies. These relatively local objects are well constrained by observations and are test cases of phenomena seen at high-z where detailed observations are rare. The tool used to study these objects is the plasma simulation code known as Cloudy. The introduction provides a brief summary of relevant physical concepts in nebular astrophysics and presents the basic features and assumptions of Cloudy. The first object investigated with Cloudy, the Crab Nebula, is a nearby supernova remnant that previously has been subject to photoionization modeling to reproduce the ionized emission seen in the nebula's filamentary structure. However, there are still several unanswered questions: (1) What excites the H2 emitting gas? (2) How much mass is in the molecular component? (3) How did the H2 form? (4) What is nature of the dust grains? A large suite of observations including long slit optical and NIR spectra over ionized, neutral and molecular gas in addition to HST and NIR ground based images constrain a particularly bright region of H2 emission, Knot 51, which exhibits a high excitation temperature of ˜3000 K. Simulations of K51 revealed that only a trace amount of H2 is needed to reproduce the observed emission and that H2 forms through an uncommon nebular process known as associative detachment. The final chapters of this dissertation focus on interpreting the narrow line region (NLR) in low-z emission line galaxies selected by a novel technique known as mean field independent component analysis (MFICA). A mixture of starlight and radiation from an AGN excites the gas present in galaxies. MFICA separates galaxies over a wide range of ionization into subsets of pure AGN and pure star forming galaxies allowing simulations to reveal the properties responsible for their observed variation in ionization. Emission line ratios can

  17. 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.

  18. Plasma depletion layer: the role of the slow mode waves

    Directory of Open Access Journals (Sweden)

    Y. L. Wang

    2004-12-01

    Full Text Available The plasma depletion layer (PDL is a layer on the sunward side of the magnetopause with lower plasma density and higher magnetic field compared to their corresponding values in the upstream magnetosheath. The depletion layer usually occurs during northward (IMF conditions with low magnetic shear across the magnetopause. We have previously validated the Raeder global model by comparing the computed formation of a magnetosheath density depletion with in-situ observations. We also have performed a detailed force analysis and found the varying roles that different MHD forces play along the path of a plasma parcel flowing around the magnetopause. That study resulted in a new description of the behavior of magnetosheath magnetic flux tubes which better explains the plasma depletion along a flux tube. The slow mode waves have been observed in the magnetosheath and have been used to explain the formation of the PDL in some of the important PDL models. In this study, we extend our former work by investigating the possible role of the slow mode waves for the formation of the PDL, using global MHD model simulations. We propose a new technique to test where a possible slow mode front may occur in the magnetosheath by comparing the slow mode group velocity with the local flow velocity. We find that the slow mode fronts can exist in certain regions in the magnetosheath under certain solar wind conditions. The existence and location of such fronts clearly depend on the IMF. We do not see from our global simulation results either the sharpening of the slow mode front into a slow mode shock or noticeable changes of the flow and field in the magnetosheath across the slow mode front, which implies that the slow mode front is not likely responsible for the formation of the PDL, at least for the stable solar wind conditions used in these simulations. Also, we do not see the two-layered slow mode structures shown in some observations and proposed in certain PDL

  19. Effects of external magnetic field on oblique propagation of ion acoustic cnoidal wave in nonextensive plasma

    Science.gov (United States)

    Farhad Kiyaei, Forough; Dorranian, Davoud

    2017-01-01

    Effects of the obliqueness and the strength of external magnetic field on the ion acoustic (IA) cnoidal wave in a nonextensive plasma are investigated. The reductive perturbation method is employed to derive the corresponding KdV equation for the IA wave. Sagdeev potential is extracted, and the condition of generation of IA waves in the form of cnoidal waves or solitons is discussed in detail. In this work, the domain of allowable values of nonextensivity parameter q for generation of the IA cnoidal wave in the plasma medium is considered. The results show that only the compressive IA wave may generate and propagate in the plasma medium. Increasing the strength of external magnetic field will increase the frequency of the wave and decrease its amplitude, while increasing the angle of propagation will decrease the frequency of the wave and increase its amplitude.

  20. Full-wave Analyses of Scattering of Electromagnetic Wave from the Weakly Ionized Plasma in Plane Geometry

    Institute of Scientific and Technical Information of China (English)

    Song Falun; Cao Jinxiang; Wang Ge

    2005-01-01

    The purpose of the present work is to present a full-wave analysis of scattering from the weakly ionized plasma in the plane geometry. We have yielded an approximate solution in an analytic form to the electromagnetic wave scattering from the weakly ionizsd plasma. In the normal and oblique incidence, the analytic solution works well, as compared with the exact solution and the solution based on the Wenzell-Kramers-Brillouin-Jeffreys (WKBJ) approximation to the uniform density profile.

  1. Wave spectra of 2D dusty plasma solids and liquids

    CERN Document Server

    Hou, Lu-Jing; Piel, Alexander; Murillo, Michael S

    2009-01-01

    Brownian dynamics simulations were carried out to study wave spectra of two-dimensional dusty plasma liquids and solids for a wide range of wavelengths. The existence of a longitudinal dust thermal mode was confirmed in simulations, and a cutoff wavenumber in the transverse mode was measured. Dispersion relations, resulting from simulations, were compared with those from analytical theories, such as the random-phase approximation (RPA), quasi-localized charged approximation (QLCA), and harmonic approximation (HA). An overall good agreement between the QLCA and simulations was found for wide ranges of states and wavelengths after taking into account the direct thermal effect in the QLCA, while for the RPA and HA good agreement with simulations were found in the high and low temperature limits, respectively.

  2. Plasma and cyclotron frequency effects on output power of the plasma wave-pumped free-electron lasers

    Science.gov (United States)

    Zolghadr, S. H.; Jafari, S.; Raghavi, A.

    2016-05-01

    Significant progress has been made employing plasmas in the free-electron lasers (FELs) interaction region. In this regard, we study the output power and saturation length of the plasma whistler wave-pumped FEL in a magnetized plasma channel. The small wavelength of the whistler wave (in sub-μm range) in plasma allows obtaining higher radiation frequency than conventional wiggler FELs. This configuration has a higher tunability by adjusting the plasma density relative to the conventional ones. A set of coupled nonlinear differential equations is employed which governs on the self-consistent evolution of an electromagnetic wave. The electron bunching process of the whistler-pumped FEL has been investigated numerically. The result reveals that for a long wiggler length, the bunching factor can appreciably change as the electron beam propagates through the wiggler. The effects of plasma frequency (or plasma density) and cyclotron frequency on the output power and saturation length have been studied. Simulation results indicate that with increasing the plasma frequency, the power increases and the saturation length decreases. In addition, when density of background plasma is higher than the electron beam density (i.e., for a dense plasma channel), the plasma effects are more pronounced and the FEL-power is significantly high. It is also found that with increasing the strength of the external magnetic field frequency, the power decreases and the saturation length increases, noticeably.

  3. A Review of Nonlinear Low Frequency (LF) Wave Observations in Space Plasmas: On the Development of Plasma Turbulence

    Science.gov (United States)

    Tsurutani, Bruce T.

    1995-01-01

    As the lead-off presentation for the topic of nonlinear waves and their evolution, we will illustrate some prominent examples of waves in space plasmas. We will describe recent observations detected within planetary foreshocks, near comets and in interplanetary space. It is believed that the nonlinear LF plasma wave features discussed here are part of and may be basic to the development of plasma turbulence. In this sense, this is one area of space plasma physics that is fundamental, with applications to fusion physics and astrophysics as well. It is hoped that the reader(s) will be stimulated to study nonlinear wave development themselves, if he/she is not already involved.

  4. Modified ion-acoustic solitary waves in plasmas with field-aligned shear flows

    Energy Technology Data Exchange (ETDEWEB)

    Saleem, H. [Department of Space Science, Institute of Space Technology, 1-Islamabad Highway, Islamabad (Pakistan); Theoretical Research Institute, Pakistan Academy of Sciences, 3-Constitution Avenue G-5/3, Islamabad (Pakistan); Ali, S. [Theoretical Research Institute, Pakistan Academy of Sciences, 3-Constitution Avenue G-5/3, Islamabad (Pakistan); National Centre for Physics (NCP) at Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Haque, Q. [Theoretical Research Institute, Pakistan Academy of Sciences, 3-Constitution Avenue G-5/3, Islamabad (Pakistan); National Centre for Physics (NCP) at Quaid-i-Azam University Campus, Shahdra Valley Road, Islamabad 44000 (Pakistan); Theoretical Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)

    2015-08-15

    The nonlinear dynamics of ion-acoustic waves is investigated in a plasma having field-aligned shear flow. A Korteweg-deVries-type nonlinear equation for a modified ion-acoustic wave is obtained which admits a single pulse soliton solution. The theoretical result has been applied to solar wind plasma at 1 AU for illustration.

  5. Generation of fast electrons by breaking of a laser-induced plasma wave

    NARCIS (Netherlands)

    Trines, Rmgm; Goloviznin, V. V.; Kamp, L. P. J.; Schep, T. J.

    2001-01-01

    A one-dimensional model for fast electron generation by an intense, nonevolving laser pulse propagating through an underdense plasma has been developed. Plasma wave breaking is considered to be the dominant mechanism behind this process, and wave breaking both in front of and behind the laser pulse

  6. geometric optics and WKB method for electromagnetic wave propagation in an inhomogeneous plasma near cutoff

    Energy Technology Data Exchange (ETDEWEB)

    Light, Max Eugene [Los Alamos National Laboratory

    2017-04-13

    This report outlines the theory underlying electromagnetic (EM) wave propagation in an unmagnetized, inhomogeneous plasma. The inhomogeneity is given by a spatially nonuniform plasma electron density ne(r), which will modify the wave propagation in the direction of the gradient rne(r).

  7. WIND observations of plasma waves inside the magnetic cloud boundary layers

    Institute of Scientific and Technical Information of China (English)

    WEI Fengsi; ZHONG Dingkun; FENG Xueshang; YANG Fang; LIU Rui

    2005-01-01

    Based on the WIND observational data for the plasma waves from thermal noise receptor (TNR) working on the frequency 4―256 kHz and the solar wind and the magnetic fields, we analyze the plasma wave activities in the 60 magnetic cloud's boundary layers (BLs) and find that there are often various plasma wave activities in the BLs, which are different from those in the adjacent solar wind (SW) and the magnetic clouds (MC). The basic characteristics are that: (1) the enhancement of the Langmuir wave near the electronic plasma frequency (fpe) is a dominant wave activity, which occupies 75% investigated samples; (2) the events enhanced both in the langmuir and ion acustic (f < fpe) waves are about 60% of investigated samples; (3) broadband, continuous enhancement events in the plasma wave activities were observed in the whole frequency band of TNR, and about 30% of the 60 samples, however, were not observed in the SW and the MC investigated events; (4) although the ratio of the temperatures between the electon and proton, Te/Tp≤1, the ion caustic wave enhancement activities are still often observed in the BLs, which makes it difficult to ex-plain them by the traditional plasma theory. New results reported in this paper further show that the magnetic cloud's BL is an important dynamic structure, which could provide useful diagnosis for understanding the cloud's BL physics and could expand a space developing space plasma wave theory.

  8. Luminescent Nanocrystalline Silicon Carbide Thin Film Deposited by Helicon Wave Plasma Enhanced Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    LU Wan-bing; YU Wei; WU Li-ping; CUI Shuang-kui; FU Guang-sheng

    2006-01-01

    Hydrogenated nanocrystalline silicon carbide (SiC) thin films were deposited on the single-crystal silicon substrate using the helicon wave plasma enhanced chemical vapor deposition (HW-PECVD) technique. The influences of magnetic field and hydrogen dilution ratio on the structures of SiC thin film were investigated with the atomic force microscopy (AFM), the Fourier transform infrared absorption (FTIR) and the transmission electron microscopy (TEM). The results indicate that the high plasma activity of the helicon wave mode proves to be a key factor to grow crystalline SiC thin films at a relative low substrate temperature. Also, the decrease in the grain sizes from the level of microcrystalline to that of nanocrystalline can be achieved by increasing the hydrogen dilution ratios. Transmission electron microscopy measurements reveal that the size of most nanocrystals in the film deposited under the higher hydrogen dilution ratios is smaller than the doubled Bohr radius of 3C-SiC (approximately 5.4 nm), and the light emission measurements also show a strong blue photoluminescence at the room temperature, which is considered to be caused by the quantum confinement effect of small-sized SiC nanocrystals.

  9. CO2 Laser Beat-Wave Experiment in an Unmagnetized Plasma

    Science.gov (United States)

    Liu, Fei; Hwang, David; Horton, Robert; Hong, Sean; Evans, Russell

    2012-10-01

    The ability to remotely generate plasma current in dense plasmas is a basic yet important investigation in experimental plasma physics and fusion energy research. It is even more advantageous if the wave penetration is independent of the electron acceleration process. Plasma current can be generated through beat-wave mixing process by launching two intense electromagnetic waves (φ>>φpe) into plasma. The beat wave formation process can be efficient if the difference frequency of the two pump waves is matched to a local resonant frequency of the medium, i.e. in this case the local plasma frequency. Beat wave can accelerate plasma electrons via quasi-linear Landau process, which has been demonstrated in a low-density plasma using microwaves.footnotetextRogers, J. H. and Hwang, D. Q., Phys. Rev. Lett. v68 p3877 (1992). The CO2 lasers provide the high tunability for the wave-particle interaction experiment at a variety of plasma densities with plasma frequency in THz range. Two sections of Lumonics TEA CO2 lasers have been modified to serve as the two pump wave sources with peak power over 100MW. The development of the tunable CO2 lasers, a high-density plasma target source and diagnostics system will be presented. The initial results of unbalanced beat-wave experiment using one high-power pulsed and one low-power CW CO2 lasers will be presented and discussed using the independent plasma source to control the φpe of the interaction region. This work is supported by U.S. DOE under Contract No. DE-FG02-10ER55083.

  10. Effective-action approach to wave propagation in scalar QED plasmas

    Science.gov (United States)

    Shi, Yuan; Fisch, Nathaniel J.; Qin, Hong

    2016-07-01

    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 give two examples: 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 plasmas are cold. These waves account for cyclotron absorption features observed in spectra of x-ray pulsars. Moreover, cutoff frequencies of the two nondegenerate electromagnetic waves are red-shifted by different amounts. These corrections need to be taken into account in order to correctly interpret diagnostic results in laser plasma experiments.

  11. Low-Frequency Electrostatic Ion Surface Waves in Magnetized Electron-Positron Plasmas

    Science.gov (United States)

    Cho, Sang-Hoon; Lee, Hee J.

    The dispersion relations of a surface ion wave propagating on the interface between a warm electron-positron plasma and vacuum when a static magnetic field is directed either normal to the interface (x-wave) or parallel to the wave vector (z-wave) are solved analytically, and the influence of the magnetic field on the ion surface wave is investigated in detail using some numerical work. It is shown that ion surface waves do not exist if the magnetic field is large enough to make the ion gyrofrequency greater than the ion plasma frequency. The attenuation constant of x-waves is more attenuated than that of z-waves and the x-wave is more attenuated as the parameter normalized ion gyrofrequency ζ increases toward 1, but this tendency is reversed for the z-wave. The z-wave does not exist for k2λD2< (ζ/(1-ζ))(p + 1) while the x-wave exists over the whole range of k, where the fractional number p is the ratio between the unperturbed positron and the electron number density. Additionally, we compare the ion surface wave properties of electron-positron plasma with conventional electron-ion plasma.

  12. Intense, Narrow-band THz Emission from a Current Source Immersed in Cut-off of Plasma-like Media

    Science.gov (United States)

    Hur, Min Sup; Ersfeld, Bernhard; Noble, Adam; Suk, Hyyong; Jaroszynski, Dino

    2016-10-01

    Recently we found an interesting behavior of the electromagnetic radiation emerging from cut-off condition of a plasma-like medium, when it is driven by a current source. Differently from conventional total reflection of the incident wave at the cut-off, we found a spatially diffusing and temporally growing electromagnetic field from the current source. Direct result of such diffusion-growth is the selectively enhanced emission (SEE) at the cut-off frequency from a generally broadband current oscillation. We demonstrate examples demonstrating the SEE. One is the two-color-driven THz emission from field ionization of the gas slab located in a tapered waveguide. The emission propagating through the waveguide exhibits a significantly enhanced spectral density at the cut-off frequency. The other example is the THz emission from a magnetized plasma driven by two colliding ultra-short laser pulses. Since a very narrow-band emission can be selectively enhanced from a broadband radiation source, the SEE concept can be used for conversion of a general broadband THz source to a narrow-band one by locating it in a meta-structure such as the waveguide or a plasma-like medium. We discuss other possible systems to which SEE can be applied.

  13. Boosting persistence time of laser-induced plasma by electric arc discharge for optical emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Eschlböck-Fuchs, S., E-mail: simon.eschlboeck-fuchs@jku.at [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Kolmhofer, P.J.; Bodea, M.A.; Hechenberger, J.G.; Huber, N. [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Rössler, R. [voestalpine Stahl GmbH, A-4031 Linz (Austria); Pedarnig, J.D., E-mail: johannes.pedarnig@jku.at [Christian Doppler Laboratory for Laser-Assisted Diagnostics, Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria)

    2015-07-01

    Plasma induced by nanosecond laser ablation is re-excited by a pulsed electric discharge and the parameters and optical emission of the plasma are measured. The discharge is a low-voltage and high-current electric arc that is triggered by the laser-induced plasma and slowly decaying with time. The optical emission of such combined plasma lasts up to several milliseconds which is much longer than without re-excitation (μs range). The emission spectra of re-excited plasma measured on different sample materials show higher line intensities than spectra measured by conventional laser-induced breakdown spectroscopy (LIBS). Moreover, emission lines of fluorine (spectral range 683–691 nm) and sulfur (range 520–550 nm) not detected by conventional LIBS become easily detectable with the combined plasma. The concentration of major components in metallurgical slags, as determined by calibration-free LIBS, agrees very well to the reference data evaluating the spectra taken from re-excited plasma. - Highlights: • Persistence time of laser-induced plasma in air is increased from ~ 10 μs to ~ 1 ms. • Laser-induced plasma triggers an electric arc discharge that boosts the plasma. • The combined laser-arc plasma is in LTE state over very long time (ms range). • CF-LIBS method delivers accurate results evaluating spectra of combined plasma. • Emission from S and F, not detected by LIBS, is detected with combined plasma.

  14. Ultrahigh-gradient acceleration of injected eletrons by laser-excited relativistic electron plasma waves

    Science.gov (United States)

    Clayton, C. E.; Marsh, K. A.; Dyson, A.; Everett, M.; Lal, A.; Leemans, W. P.; Williams, R.; Joshi, C.

    1993-01-01

    High-gradient acceleration of externally injected 2.1-MeV electrons by a laser beat wave driven relativistic plasma wave has been demonstrated for the first time. Electrons with energies up to the detection limit of 9.1 MeV were detected when such a plasma wave was resonantly excited using a two-frequency laser. This implies a gradient of 0.7 GeV/m, corresponding to a plasma-wave amplitude of more than 8%. The electron signal was below detection threshold without injection or when the laser was operated on a single frequency.

  15. Characteristics of Plasma Shock Waves Generated in the Pulsed Laser Ablation Process

    Institute of Scientific and Technical Information of China (English)

    李智华; 张端明; 郁伯铭; 关丽

    2002-01-01

    We modify the Sedov theory to describe plasma shock waves generated in a pulsed laser ablating process. We also study the propagation characteristics of plasma shock waves during the preparation process of functional thin films deposited by a pulsed laser. In particular, we discuss in detail the temporal behaviour of energy causing the difference of the propagation characteristics between the plasma shock wave and the ideal shock wave in the point explosion model. Under the same experimental conditions, the theoretical results calculated with our modified Sedov theory are in good agreement with the existing experimental data.

  16. Impact of the Collisional Plasma on the Propagation of Millimeter Waves

    Institute of Scientific and Technical Information of China (English)

    袁忠才; 时家明; 汪家春; 许波

    2004-01-01

    The plasma generated in the low-altitude atmosphere is of high collision frequencies.In this paper, the transmission coefficients of millimeter(MM) waves normally incident upon the plasma with high collision frequencies are calculated and analyzed. The experimental results of reflection and attenuation are presented for the eight-millimeter waves propagating through the plasma. Both the calculated experimental results indicate that the MM-waves concerned are attenuated significantly and reflected weakly, when propagating through the plasma of high collision frequencies.

  17. The Nonlinear Langmuir Waves in a Multi-ion-Component Plasma

    Institute of Scientific and Technical Information of China (English)

    CHEN Yin-Hua; LU Wei; WANG Wen-Hao

    2001-01-01

    We investigated the nonlinear Langmuir waves in a multi-ion-component low-temperature plasma. Beginning with the fluid theory of plasma, and taking fully nonlinear response of the low-frequency ion motion into account, we derived a set of equations governing the nonlinear coupling of the amplitude of the Langmuir wave and the Iow-frequency perturbation density. Using the Sagdeev potential method, we analyzed the characteristics of solitary wave. In the limit of small amplitude, the envelope soliton was found. Our investigation demonstrates that the properties of soliton in a multi-ion-component plasma are different from those of soliton in an electron-ion plasma.

  18. Enhanced acceleration of injected electrons in a laser-beat-wave-induced plasma channel.

    Science.gov (United States)

    Tochitsky, S Ya; Narang, R; Filip, C V; Musumeci, P; Clayton, C E; Yoder, R B; Marsh, K A; Rosenzweig, J B; Pellegrini, C; Joshi, C

    2004-03-05

    Enhanced energy gain of externally injected electrons by a approximately 3 cm long, high-gradient relativistic plasma wave (RPW) is demonstrated. Using a CO2 laser beat wave of duration longer than the ion motion time across the laser spot size, a laser self-guiding process is initiated in a plasma channel. Guiding compensates for ionization-induced defocusing (IID) creating a longer plasma, which extends the interaction length between electrons and the RPW. In contrast to a maximum energy gain of 10 MeV when IID is dominant, the electrons gain up to 38 MeV energy in a laser-beat-wave-induced plasma channel.

  19. The effect of lower hybrid waves on JET plasma rotation

    Science.gov (United States)

    Nave, M. F. F.; Kirov, K.; Bernardo, J.; Brix, M.; Ferreira, J.; Giroud, C.; Hawkes, N.; Hellsten, T.; Jonsson, T.; Mailloux, J.; Ongena, J.; Parra, F.; Contributors, JET

    2017-03-01

    This paper reports on observations of rotation in JET plasmas with lower hybrid current drive. Lower hybrid (LH) has a clear impact on rotation. The changes in core rotation can be either in the co- or counter-current directions. Experimental features that could determine the direction of rotation were investigated. Changes from co- to counter-rotation as the q-profile evolves from above unity to below unity suggests that magnetic shear could be important. However, LH can drive either co- or counter-rotation in discharges with similar magnetic shear and at the same plasma current. It is not clear if a slightly lower density is significant. A power scan at fixed density, shows a lower hybrid power threshold around 3 MW. For smaller LH powers, counter rotation increases with power, while for larger powers a trend towards co-rotation is found. The estimated counter-torque from the LH waves, would not explain the observed angular frequencies, neither would it explain the observation of co-rotation.

  20. Resonant Alfven waves in partially ionized plasmas of the solar atmosphere

    CERN Document Server

    Soler, R; Goossens, M

    2011-01-01

    Context. Magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere. In magnetic waveguides resonant absorption due to plasma inhomogeneity naturally transfers wave energy from large-scale motions to small-scale motions. In the cooler parts of the solar atmosphere as, e.g., the chromosphere, effects due to partial ionization may be relevant for wave dynamics and heating. Aims. We study resonant Alfven waves in partially ionized plasmas. Methods. We use the multifluid equations in the cold plasma approximation. We investigate propagating resonant MHD waves in partially ionized flux tubes. We use approximate analytical theory based on normal modes in the thin tube and thin boundary approximations along with numerical eigenvalue computations. Results. We find that the jumps of the wave perturbations across the resonant layer are the same as in fully ionized plasmas. The damping length due to resonant absorption is inversely proportional to the frequency, while that due to ion-neutral collisions is in...

  1. Power Absorption of High Frequency Electromagnetic Waves in a Partially Ionized Plasma Layer in Atmosphere Conditions

    Institute of Scientific and Technical Information of China (English)

    郭斌; 王晓钢

    2005-01-01

    We have studied the absorption, reflection, and transmission of electromagnetic waves in an unmagnetized uniform plasma layer covering a metal surface in atmosphere conditions.Instead of the absorption of the electromagnetic wave propagating only once in previous work on the plasma layer, a general formula of total power absorption by the plasma layer with an infinite time of reflections between the atmosphere-plasma interface and the metal surface has been derived for the first time. Effects of plasma parameters, especially the dependence of the fraction of positive ions, negative ions and electrons in plasmas on the power absorption processes are discussed. The results show that the existence of negative ions significantly reduces the power absorption of the electromagnetic wave. Absorptions of electromagnetic waves are calculated.

  2. Molecular emission in the edge plasma of T-10 tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Zimin, A. M., E-mail: zimin@power.bmstu.ru [Bauman Moscow State Technical University (Russian Federation); Krupin, V. A. [National Research Centre Kurchatov Institute (Russian Federation); Troynov, V. I. [Bauman Moscow State Technical University (Russian Federation); Klyuchnikov, L. A. [National Research Centre Kurchatov Institute (Russian Federation)

    2015-12-15

    The experiments on recording molecular emission in the edge plasma of the T-10 tokamak are described. To obtain reliable spectra with sufficient spectral, temporal, and spatial resolution, the optical circuit is optimized for various experimental conditions. Typical spectra measured in two sections of the tokamak are shown. It is shown that, upon varying the parameters of the discharge, the molecular spectrum not only changes significantly in intensity but also undergoes a qualitative change in the rotational and vibrational structure. For a detailed analysis, we use the Fulcher-α system (d{sup 3}Π{sub u}–a{sup 3}Σ{sub g}{sup +}) of deuterium in the wavelength range from 590 to 640 nm. The rotational temperatures of ground state X{sup 1}Σ{sub g}{sup +} and upper excited state d{sup 3}Π{sub u} are estimated by the measured spectra.

  3. Observations of Microwave Continuum Emission from Air Shower Plasmas

    CERN Document Server

    Gorham, P W; Varner, G S; Beatty, J J; Connolly, A; Chen, P; Conde, M E; Gai, W; Hast, C; Hebert, C L; Miki, C; Konecny, R; Kowalski, J; Ng, J; Power, J G; Reil, K; Saltzberg, D; Stokes, B T; Walz, D

    2007-01-01

    We investigate a possible new technique for microwave measurements of ultra-high energy cosmic ray (UHECR) extensive air showers which relies on detection of expected continuum radiation in the microwave range, caused by free-electron collisions with neutrals in the tenuous plasma left after the passage of the shower. We performed an initial experiment at the AWA (Argonne Wakefield Accelerator) laboratory in 2003 and measured broadband microwave emission from air ionized via high energy electrons and photons. A follow-up experiment at SLAC (Stanford Linear Accelerator Center) in summer of 2004 confirmed the major features of the previous AWA observations with better precision and made additional measurements relevant to the calorimetric capabilities of the method. Prompted by these results we built a prototype detector using satellite television technology, and have made measurements indicating possible detection of cosmic ray extensive air showers. The method, if confirmed by experiments now in progress, cou...

  4. Emission of Whistler-mode waves and diffusion of electrons around interplanetary shocks

    Science.gov (United States)

    Pierre, F.; Solomon, J.; Cornilleau-Wehrlin, N.; Canu, P.; Scime, E. E.; Phillips, J. L.; Balogh, A.; Forsyth, R.

    1995-01-01

    Whistler-mode wave emissions are frequently observed at and downstream of interplanetary shocks. Using electron distribution functions measured onboard Ulysses in the energy range 1.6 to 862 eV, we calculate the temperature anisotropy and the wave growth rate of the electromagnetic electron cyclotron instability, Results of the calculations are compared to the whistler wave spectra observed simultaneously. For the studied events there is a good correlation between the wave growth rates and the wave spectra. Particularly, upstream of the shock front where no wave emissions are observed, the anisotropy lies below the wave instability threshold, i.e. the critical anisotropy Ac; on the contrary, downstream of the shock, the anisotropy exceeds Ac in some frequency range. Moreover. the tact that the anisotropy is close to Ac in a large frequency range gives prominence to the effect of velocity space diffusion of the electrons by the waves.

  5. Modulational instability of ion-acoustic waves in a warm plasma

    Institute of Scientific and Technical Information of China (English)

    薛具奎; 段文山; 郎和

    2002-01-01

    Using the standard reductive perturbation technique, a nonlinear Schrodinger equation is derived to study themodulational instability of finite-amplitude ion-acoustic waves in a non-magnetized warm plasma. It is found thatthe inclusion of ion temperature in the equation modifies the nature of the ion-acoustic wave stability and the solitonstructures. The effects of ion plasma temperature on the modulational stability and ion-acoustic wave properties areinvestigated in detail.

  6. Nonlinear coupling of kinetic Alfven waves with acoustic waves in a self-gravitating dusty plasma with adiabatic trapping

    Science.gov (United States)

    Sabeen, A.; Masood, W.; Qureshi, M. N. S.; Shah, H. A.

    2017-07-01

    In this paper, linear and nonlinear coupling of kinetic Alfven and acoustic waves has been studied in a dusty plasma in the presence of trapping and self-gravitation effects. In this regard, we have derived the linear dispersion relations for positively and negatively coupled dust kinetic Alfven-acoustic waves. Stability analysis of the coupled dust kinetic Alfven-acoustic wave has also been presented. The formation of solitary structures has been investigated following the Sagdeev potential approach by using the two-potential theory. Numerical results show that the solitary structures can be obtained only for sub-Alfvenic regimes in the scenario of space plasmas.

  7. Nonlinear acoustic waves in a collisional self-gravitating dusty plasma

    Institute of Scientific and Technical Information of China (English)

    Guo Zhi-Rong; Yang Zeng-Qiang; Yin Bao-Xiang; Sun Mao-Zhu

    2010-01-01

    Using the reductive perturbation method,we investigate the small amplitude nonlinear acoustic wave in a collisional self-gravitating dusty plasma.The result shows that the small amplitude dust acoustic wave can be expressed by a modified Korteweg-de Vries equation,and the nonlinear wave is instable because of the collisions between the neutral gas molecules and the charged particles.

  8. Filtration of Carbon Particulate Emissions from a Plasma Pyrolysis Assembly

    Science.gov (United States)

    Agui, Juan H.; Green, Robert; Vijayakumar, R.; Berger, Gordon; Greenwood, Zach; Abney, Morgan; Peterson, Elspeth

    2016-01-01

    NASA is investigating plasma pyrolysis as a candidate technology that will enable the recovery of hydrogen from the methane produced by the ISS Sabatier Reactor. The Plasma Pyrolysis Assembly (PPA) is the current prototype of this technology which converts the methane product from the Carbon Dioxide Reduction Assembly (CRA) to acetylene and hydrogen with 90% or greater conversion efficiency. A small amount of solid carbon particulates are generated as a side product and must be filtered before the acetylene is removed and the hydrogen-rich gas stream is recycled back to the CRA. We discuss developmental work on several options for filtering out the carbon particulate emissions from the PPA exit gas stream. The filtration technologies and concepts investigated range from fibrous media to monolithic ceramic and sintered metal media. This paper describes the different developed filter prototypes and characterizes their performance from integrated testing at the Environmental Chamber (E-Chamber) at MSFC. In addition, characterization data on the generated carbon particulates, that help to define filter requirements, are also presented.

  9. On the rogue waves propagation in non-Maxwellian complex space plasmas

    Science.gov (United States)

    El-Tantawy, S. A.; El-Awady, E. I.; Tribeche, M.

    2015-11-01

    The implications of the non-Maxwellian electron distributions (nonthermal/or suprathermal/or nonextensive distributions) are examined on the dust-ion acoustic (DIA) rogue/freak waves in a dusty warm plasma. Using a reductive perturbation technique, the basic set of fluid equations is reduced to a nonlinear Schrödinger equation. The latter is used to study the nonlinear evolution of modulationally unstable DIA wavepackets and to describe the rogue waves (RWs) propagation. Rogue waves are large-amplitude short-lived wave groups, routinely observed in space plasmas. The possible region for the rogue waves to exist is defined precisely for typical parameters of space plasmas. It is shown that the RWs strengthen for decreasing plasma nonthermality and increasing superthermality. For nonextensive electrons, the RWs amplitude exhibits a bit more complex behavior, depending on the entropic index q. Moreover, our numerical results reveal that the RWs exist with all values of the ion-to-electron temperature ratio σ for nonthermal and superthermal distributions and there is no limitation for the freak waves to propagate in both two distributions in the present plasma system. But, for nonextensive electron distribution, the bright- and dark-type waves can propagate in this case, which means that there is a limitation for the existence of freak waves. Our systematic investigation should be useful in understanding the properties of DIA solitary waves that may occur in non-Maxwellian space plasmas.

  10. On the rogue waves propagation in non-Maxwellian complex space plasmas

    Energy Technology Data Exchange (ETDEWEB)

    El-Tantawy, S. A., E-mail: samireltantawy@yahoo.com; El-Awady, E. I., E-mail: eielawady@hotmail.com [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt); Tribeche, M., E-mail: mouloudtribeche@yahoo.fr, E-mail: mtribeche@usthb.dz [Plasma Physics Group, Theoretical Physics Laboratory, Faculty of Physics, University of Bab-Ezzouar, USTHB, BP 32, El Alia, Algiers 16111 (Algeria)

    2015-11-15

    The implications of the non-Maxwellian electron distributions (nonthermal/or suprathermal/or nonextensive distributions) are examined on the dust-ion acoustic (DIA) rogue/freak waves in a dusty warm plasma. Using a reductive perturbation technique, the basic set of fluid equations is reduced to a nonlinear Schrödinger equation. The latter is used to study the nonlinear evolution of modulationally unstable DIA wavepackets and to describe the rogue waves (RWs) propagation. Rogue waves are large-amplitude short-lived wave groups, routinely observed in space plasmas. The possible region for the rogue waves to exist is defined precisely for typical parameters of space plasmas. It is shown that the RWs strengthen for decreasing plasma nonthermality and increasing superthermality. For nonextensive electrons, the RWs amplitude exhibits a bit more complex behavior, depending on the entropic index q. Moreover, our numerical results reveal that the RWs exist with all values of the ion-to-electron temperature ratio σ for nonthermal and superthermal distributions and there is no limitation for the freak waves to propagate in both two distributions in the present plasma system. But, for nonextensive electron distribution, the bright- and dark-type waves can propagate in this case, which means that there is a limitation for the existence of freak waves. Our systematic investigation should be useful in understanding the properties of DIA solitary waves that may occur in non-Maxwellian space plasmas.

  11. Beating the Spin-Down Limit on Gravitational Wave Emission from the Crab Pulsar

    Science.gov (United States)

    Abbott, B.; Abbott, R.; Adhikari, R.; Ajith, P.; Allen, B.; Allen, G.; Amin, R.; Anderson, S. B.; Anderson, W. G.; Arain, M. A.; Araya, M.; Armandula, H.; Armor, P.; Aso, Y.; 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. A.; Bastarrika, M.; Bayer, K.; Betzwieser, J.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Biswas, R.; Black, E.; Blackburn, K.; Blackburn, L.; Blair, D.; Bland, B.; Bodiya, T. P.; Bogue, L.; Bork, R.; Boschi, V.; Bose, S.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Brinkmann, M.; Brooks, A.; Brown, D. A.; Brunet, G.; Bullington, A.; Buonanno, A.; Burmeister, O.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Camp, J. B.; Cannizzo, J.; Cannon, K.; Cao, J.; Cardenas, L.; Casebolt, T.; Castaldi, G.; Cepeda, C.; Chalkley, E.; Charlton, P.; Chatterji, S.; Chelkowski, S.; Chen, Y.; Christensen, N.; Clark, D.; Clark, J.; Cokelaer, T.; Conte, R.; Cook, D.; Corbitt, T.; Coyne, D.; Creighton, J. D. E.; Cumming, A.; Cunningham, L.; Cutler, R. M.; Dalrymple, J.; Danzmann, K.; Davies, G.; DeBra, D.; Degallaix, J.; Degree, M.; Dergachev, V.; Desai, S.; DeSalvo, R.; Dhurandhar, S.; Díaz, M.; Dickson, J.; Dietz, A.; Donovan, F.; Dooley, K. L.; Doomes, E. E.; Drever, R. W. P.; Duke, I.; Dumas, J.-C.; Dupuis, R. J.; Dwyer, J. G.; Echols, C.; Effler, A.; Ehrens, P.; Espinoza, E.; Etzel, T.; Evans, T.; Fairhurst, S.; Fan, Y.; Fazi, D.; Fehrmann, H.; Fejer, M. M.; Finn, L. S.; Flasch, K.; Fotopoulos, N.; Freise, A.; Frey, R.; Fricke, T.; Fritschel, P.; Frolov, V. V.; Fyffe, M.; Garofoli, J.; Gholami, I.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Goda, K.; Goetz, E.; Goggin, L.; González, G.; Gossler, S.; Gouaty, R.; Grant, A.; Gras, S.; Gray, C.; Gray, M.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Grimaldi, F.; Grosso, R.; Grote, H.; Grunewald, S.; Guenther, M.; Gustafson, E. K.; Gustafson, R.; Hage, B.; Hallam, J. M.; Hammer, D.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G.; Harstad, E.; Hayama, K.; Hayler, T.; Heefner, J.; Heng, I. S.; Hennessy, M.; Heptonstall, A.; Hewitson, M.; Hild, S.; Hirose, E.; Hoak, D.; Hosken, D.; Hough, J.; Huttner, S. H.; Ingram, D.; Ito, M.; Ivanov, A.; Johnson, B.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kamat, S.; Kanner, J.; Kasprzyk, D.; Katsavounidis, E.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Keppel, D. G.; Khalili, F. Ya.; Khan, R.; Khazanov, E.; Kim, C.; King, P.; Kissel, J. S.; Klimenko, S.; Kokeyama, K.; Kondrashov, V.; Kopparapu, R. K.; Kozak, D.; Kozhevatov, I.; Krishnan, B.; Kwee, P.; Lam, P. K.; Landry, M.; Lang, M. M.; Lantz, B.; Lazzarini, A.; Lei, M.; Leindecker, N.; Leonhardt, V.; Leonor, I.; Libbrecht, K.; Lin, H.; Lindquist, P.; Lockerbie, N. A.; Lodhia, D.; Lormand, M.; Lu, P.; Lubinski, M.; Lucianetti, A.; Lück, H.; Machenschalk, B.; MacInnis, M.; Mageswaran, M.; Mailand, K.; Mandic, V.; Márka, S.; Márka, Z.; Markosyan, A.; Markowitz, J.; Maros, E.; Martin, I.; Martin, R. M.; Marx, J. N.; Mason, K.; Matichard, F.; Matone, L.; Matzner, R.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McHugh, M.; McIntyre, G.; McIvor, G.; McKechan, D.; McKenzie, K.; Meier, T.; Melissinos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C. J.; Meyers, D.; Miller, J.; Minelli, J.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Moe, B.; Mohanty, S.; Moreno, G.; Mossavi, K.; MowLowry, C.; Mueller, G.; Mukherjee, S.; Mukhopadhyay, H.; Müller-Ebhardt, H.; Munch, J.; Murray, P.; Myers, E.; Myers, J.; Nash, T.; Nelson, J.; Newton, G.; Nishizawa, A.; Numata, K.; O'Dell, J.; Ogin, G.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Pan, Y.; Pankow, C.; Papa, M. A.; Parameshwaraiah, V.; Patel, P.; Pedraza, M.; Penn, S.; Perreca, A.; Petrie, T.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Postiglione, F.; Principe, M.; Prix, R.; Quetschke, V.; Raab, F.; Rabeling, D. S.; Radkins, H.; Rainer, N.; Rakhmanov, M.; Ramsunder, M.; Rehbein, H.; Reid, S.; Reitze, D. H.; Riesen, R.; Riles, K.; Rivera, B.; Robertson, N. A.; Robinson, C.; Robinson, E. L.; Roddy, S.; Rodriguez, A.; Rogan, A. M.; Rollins, J.; Romano, J. D.; Romie, J.; Route, R.; Rowan, S.; Rüdiger, A.; Ruet, L.; Russell, P.; Ryan, K.; 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. W.; 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.; Siemens, X.; Sigg, D.; Sinha, S.; Sintes, A. M.

    2008-08-01

    We present direct upper limits on gravitational wave emission from the Crab pulsar using data from the first 9 months of the fifth science run of the Laser Interferometer Gravitational-wave Observatory (LIGO). These limits are based on two searches. In the first we assume that the gravitational wave emission follows the observed radio timing, giving an upper limit on gravitational wave emission that beats indirect limits inferred from the spin-down and braking index of the pulsar and the energetics of the nebula. In the second we allow for a small mismatch between the gravitational and radio signal frequencies and interpret our results in the context of two possible gravitational wave emission mechanisms.

  12. Plasma Shock Wave Modification Experiments in a Temperature Compensated Shock Tube

    Science.gov (United States)

    Vine, Frances J.; Mankowski, John J.; Saeks, Richard E.; Chow, Alan S.

    2003-01-01

    A number of researchers have observed that the intensity of a shock wave is reduced when it passes through a weakly ionized plasma. While there is little doubt that the intensity of a shock is reduced when it propagates through a weakly ionized plasma, the major question associated with the research is whether the reduction in shock wave intensity is due to the plasma or the concomitant heating of the flow by the plasma generator. The goal of this paper is to describe a temperature compensated experiment in a "large" diameter shock tube with an external heating source, used to control the temperature in the shock tube independently of the plasma density.

  13. Optical Emission Spectroscopic Studies of ICP Ar Plasma

    Institute of Scientific and Technical Information of China (English)

    QI Xuelian; REN Chunsheng; ZHANG Jian; MA Tengcai

    2007-01-01

    The ion line of 434.8 nm and atom line of 419.8 nm of Ar plasma produced by an inductively coupled plasma (ICP) were measured by optical emission spectroscopy and the influences from the working gas pressure, radio-frequency (RF) power and different positions in the discharge chamber on the line intensities were investigated in this study. It was found that the intensity of Ar atom line increased firstly and then saturated with the increase of the pressure. The line intensity of Ar+, on the other hand, reached a maximum value and then decreased along with the pressure. The intensity of the line in an RF discharge also demonstrated a jumping mode and a hysteresis phenomenon with the RF power. When the RF power increased to 400 W, the discharge jumped from the E-mode to the H-mode where the line intensity of Ar atom demonstrated a sudden increase, while the intensity of Ar+ ion only changed slightly. If the RF power decreased from a high value, e.g., 1000 W, the discharge would jump from the H-mode back to the E-mode at a power of 300 W. At this time the intensities of Ar and Ar+ lines would also decrease sharply. It was also noticed in this paper that the intensity of the ion line depended on the detective location in the chamber, namely at the bottom of the chamber the line was more intense than that in the middle of the chamber, but less intense than at the top, which is considered to be related to the capacitance coupling ability of the ICP plasma in different discharge areas.

  14. 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.

  15. New numerical tools to study waves and instabilities of flowing plasmas

    NARCIS (Netherlands)

    Beliën, A.J.C.; Botchev, M.A.; Goedbloed, J.P.; Holst, van der B.; Keppens, R.

    2002-01-01

    Studying plasma waves and instabilities is an indispensable part of present thermonuclear fusion and astrophysical magnetohydrodynamics (MHD). Up till recently, spectral analysis was mostly restricted to static plasmas. However, the assumption of a static plasma is unrealistic not only for astrophys

  16. Electrostatic Waves in Dense Dusty Plasmas with High Fugacity

    Science.gov (United States)

    Rao, N. N.

    Propagation of electrostatic dust modes has been reviewed in the light of the concept of dust fugacity defined by f≡4πnd0λD2R, where nd0 and R are the dust number density and the grain size (radius) while the plasma Debye length (λD) is given through λD-2=λDe-2+λDi-2. Dusty plasmas are defined to be tenuous, dilute or dense when f≪1, ˜1, or ≫1, respectively. Attention is focused on “Dust-Acoustic Waves” (DAWs) and “Dust-Coulomb Waves” (DCWs) which exist in the tenuous (f≪1) and the dense (f≫1) regimes, respectively. A simple physical picture of the DCWs has been proposed in terms of an effective pressure called “Coulomb Pressure defined by PC≡nd0qd02/R, where qd0 is the grain charge. In the lowest order, the DCW phase speed is given by ω/k=PC/ρdδ, where ρd≡nd0md is the dust mass density and δ≡ω2/ω1 is the ratio of charging frequencies. Thus, DCWs which are driven by the Coulomb pressure can be considered as the electrostatic analogue of hydromagnetic (Alfvén or magnetoacoustic) modes which are driven by magnetic field pressure. In the dilute regime, the two waves loose their identities and merge into a single mode, which may be called “Dust Charge-Density Wave” (DCDW). When the grains are closest, DCW dispersion relation is identical with that of “Dust-Lattice Waves” (DLWs). Dense dusty plasmas are governed by a new scale-length defined by λR≡1/4πnd0Rδ, which characterizes the effective shielding length due to grain collective interactions. The scale-length λR plays a fundamental role in dense dusty plasmas, which is very similar to that of the Debye length λD in the tenuous regime. The two scale-lengths are related to the fugacity through fδ≡λD2/λR2. The frequency spectrum as well as the damping rates for various dust modes have been analytically obtained, and compared with the numerical solutions of the kinetic (Vlasov) dispersion relation.

  17. Attenuation correction for X-ray emission computed tomography of laser-produced plasma

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yen-Wei; Nakao, Zensho [Ryukyus Univ., Nishihara, Okinawa (Japan). Faculty of Engineering; Tamura, Shinichi

    1996-08-01

    An attenuation correction method was proposed for laser-produced plasma emission computed tomography (ECT), which is based on a relation of the attenuation coefficient and the emission coefficient in plasma. Simulation results show that the reconstructed images are dramatically improved in comparison to the reconstructions without attenuation correction. (J.P.N.)

  18. Millimeter-wave receiver design for plasma diagnostics

    DEFF Research Database (Denmark)

    Leipold, Frank; Hansen, S. K.; Jacobsen, Asger Schou;

    2016-01-01

    Scattered millimeter waves entering from the collective Thomson scattering diagnostic at ASDEX Upgrade fusion device are generally elliptically polarized. In order to convert the millimeter waves to linearly polarized waves (required for the detector), birefringent window assemblies (sapphire) have...

  19. The FIELDS Instrument Suite for Solar Probe Plus. Measuring the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence, and Radio Signatures of Solar Transients

    Science.gov (United States)

    Bale, S. D.; Goetz, K.; Harvey, P. R.; Turin, P.; Bonnell, J. W.; Dudok de Wit, T.; Ergun, R. E.; MacDowall, R. J.; Pulupa, M.; Andre, M.; Bolton, M.; Bougeret, J.-L.; Bowen, T. A.; Burgess, D.; Cattell, C. A.; Chandran, B. D. G.; Chaston, C. C.; Chen, C. H. K.; Choi, M. K.; Connerney, J. E.; Cranmer, S.; Diaz-Aguado, M.; Donakowski, W.; Drake, J. F.; Farrell, W. M.; Fergeau, P.; Fermin, J.; Fischer, J.; Fox, N.; Glaser, D.; Goldstein, M.; Gordon, D.; Hanson, E.; Harris, S. E.; Hayes, L. M.; Hinze, J. J.; Hollweg, J. V.; Horbury, T. S.; Howard, R. A.; Hoxie, V.; Jannet, G.; Karlsson, M.; Kasper, J. C.; Kellogg, P. J.; Kien, M.; Klimchuk, J. A.; Krasnoselskikh, V. V.; Krucker, S.; Lynch, J. J.; Maksimovic, M.; Malaspina, D. M.; Marker, S.; Martin, P.; Martinez-Oliveros, J.; McCauley, J.; McComas, D. J.; McDonald, T.; Meyer-Vernet, N.; Moncuquet, M.; Monson, S. J.; Mozer, F. S.; Murphy, S. D.; Odom, J.; Oliverson, R.; Olson, J.; Parker, E. N.; Pankow, D.; Phan, T.; Quataert, E.; Quinn, T.; Ruplin, S. W.; Salem, C.; Seitz, D.; Sheppard, D. A.; Siy, A.; Stevens, K.; Summers, D.; Szabo, A.; Timofeeva, M.; Vaivads, A.; Velli, M.; Yehle, A.; Werthimer, D.; Wygant, J. R.

    2016-12-01

    NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products.

  20. Co-existence of Whistler Waves with Kinetic Alfven Wave Turbulence for the High-beta Solar Wind Plasma

    CERN Document Server

    Mithaiwala, Manish; Crabtree, Chris; Ganguli, Gurudas

    2012-01-01

    It is shown that the dispersion relation for whistler waves is identical for a high or low beta plasma. Furthermore in the high-beta solar wind plasma whistler waves meet the Landau resonance with electrons for velocities less than the thermal speed, and consequently the electric force is small compared to the mirror force. As whistlers propagate through the inhomogeneous solar wind, the perpendicular wave number increases through refraction, increasing the Landau damping rate. However, the whistlers can survive because the background kinetic Alfven wave turbulence creates a plateau by quasilinear diffusion in the solar wind electron distribution at small velocities. It is found that for whistler energy density of only ~10^-3 that of the kinetic Alfven waves, the quasilinear diffusion rate due to whistlers is comparable to KAW. Thus very small amplitude whistler turbulence can have a significant consequence on the evolution of the solar wind electron distribution function.

  1. Results of direct measurements of the plasma potential using a laser-heated emissive probe

    Energy Technology Data Exchange (ETDEWEB)

    Schrittwieser, R.; Sarma, A.; Amarandei, G.; Ionita, C. [Univ. of Innsbruck (Austria). Inst. for Ion Physics; Klinger, T.; Grulke, O.; Vogelsang, A.; Windisch, T. [Max Planck Inst. for Plasma Physics, Greifswald (Germany)

    2006-04-15

    Reliable diagnostics of the plasma potential is one of the most important challenges in context with the production, control and confinement of a plasma. Emissive probes are readily available as direct diagnostic tools for the plasma potential with a good temporal and spatial resolution in many plasmas, even up to middle-sized fusion experiments. We present the results of investigations on the heating of lanthanum hexaboride and graphite with an infrared diode laser and on the development of a laser-heated emissive probe. Such a probe has a higher electron emission, much longer life time and better time response than a conventional emissive wire probe. We have observed that from both materials electron emission current can be achieved sufficiently strongly even for dense laboratory and experimental fusion plasmas.

  2. Absorption of laser radiation by femtosecond laser-induced plasma of air and its emission characteristics

    Science.gov (United States)

    Ilyin, A. A.; Golik, S. S.; Shmirko, K. A.

    2015-11-01

    The energy absorbed by femtosecond laser plasma has nonlinear dependence on incident laser energy. The threshold power for plasma formation is 5.2 GW. Emission of nitrogen molecule, nitrogen molecule ion, atomic oxygen (unresolved triplet O I 777 nm) and nitrogen (triplet N I 742.4, 744.3 and 746.8 nm) lines is detected. Molecular emission consists of second positive and firs negative systems of nitrogen. Time-resolved spectroscopy of plasmas shows short molecular line emission (up to 1 ns) and long atomic line emission (up to 150 ns).

  3. Plasma-Maser Instability of the Electromagnetic Radiation In The Presence Of Electrostatic Drift Wave Turbulence in Inhomogeneous Plasma

    Directory of Open Access Journals (Sweden)

    Mahinder Singh

    2016-10-01

    Full Text Available The generation mechanism of the electromagnetic radiation in case of inhomogeneous plasma on the basis of plasma-maser interaction in presence of drift wave turbulence is studied. The drift wave turbulence is taken as the low-frequency mode field and is found to be strongly in phase relation with thermal particles and may transfer its wave energy nonlinearly through a modulated field of high-frequency extraordinary mode (X-mode wave. It has been found that amplification of X-mode wave is possible at the expense of drift wave turbulent energy. This type of high-frequency instability can leads to auroral kilometric radiation (AKR. The growth rate of the X-mode wave, in the form of AKR, has been calculated with the involvement of spatial density gradient parameter. This result may be particularly important for stability of various drift modes in magnetically confined plasma as well as for transport of momentum and energy in such inhomogeneous plasma

  4. Absorption of electromagnetic waves by the dust particles in a plasma

    Institute of Scientific and Technical Information of China (English)

    LI; Fang; LI; Lianlin; SUI; Qiang

    2004-01-01

    Absorption of electromagnetic waves by the dust particles in a plasma has been studied based on a Mie-Debye scattering mode. The longitudinal field of the Debye scattering has been derived and the wave energy loss from it has been calculated. It is shown that the lower the temperature of the plasma is and the higher the density of the plasma is, the larger the absorption cross section will be due to the longitudinal scattering.For the low frequency waves the electromagnetic waves scattered in a dusty plasma are mainly in the form of Debye scattering. In this case the energy loss due to the longitudinal scattering will affect the wave propagation seriously.

  5. Plasma acceleration by the interaction of parallel propagating Alfv\\'en waves

    CERN Document Server

    Mottez, Fabrice

    2014-01-01

    It is shown that two circularly polarised Alfv\\'en waves that propagate along the ambient magnetic field in an uniform plasma trigger non oscillating electromagnetic field components when they cross each other. The non-oscilliating field components can accelerate ions and electrons with great efficiency. This work is based on particle-in-cell (PIC) numerical simulations and on analytical non-linear computations. The analytical computations are done for two counter-propagating monochromatic waves. The simulations are done with monochromatic waves and with wave packets. The simulations show parallel electromagnetic fields consistent with the theory, and they show that the particle acceleration result in plasma cavities and, if the waves amplitudes are high enough, in ion beams. These acceleration processes could be relevant in space plasmas. For instance, they could be at work in the auroral zone and in the radiation belts of the Earth magnetosphere. In particular, they may explain the origin of the deep plasma...

  6. Development of Small Plasma Wave Receiver with a Dedicated Chip for Scientific Spacecraft

    Science.gov (United States)

    Fukuhara, H.; Kojima, H.; Ishii, H.; Okada, S.; Yamakawa, H.

    2012-04-01

    Since space is filled with collisionless plasmas, kinetic energy of each particle of the plasmas is exchanged via electric and magnetic fields, so-called plasma waves. The plasma waves have been observed a number of scientific spacecraft. Plasma wave receivers are classified into two kinds of the receiver, spectrum receivers, and waveform receivers. The spectrum receivers provide an overview of the plasma waves. The waveform receivers give not only amplitude but also phase of the plasma waves. Phase information between the plasma waves and plasma particle is essential in wave-particle interactions. It is important for understanding physical processes to combine both kinds of data of spectra and waveforms. Since the plasma waves have various intensities in wide-band frequency range, from DC to tens of MHz, the onboard instruments for the plasma wave observation are required to have low noise, high sensitivity, and wide dynamic range in wide-band. The required performances lead to increase the weight budget of the analog part of the instrument. The dedicated system chip can drastically decrease weight budget of the plasma wave instruments for multi-point observation missions and deep space exploration missions. It is also significant that manufacturing a number of instruments with the same performance becomes easy. In this paper, we demonstrate the miniaturized plasma wave receiver, which is realized in a dedicated chip for the analog part. The spectrum receiver is a double super heterodyne receiver, so-called `Sweep Frequency Analyzer (SFA).' This SFA is improved in the time resolution with keeping good frequency resolution by combining the analog frequency conversion and FFT. The SFA consists of an amplifier, a frequency synthesizer, mixers and band-pass filters. These component circuits are fabricated in chips and their performances are tested. The waveform receiver generally consists of the band-limiting filter, the amplifier, the anti-aliasing filter, and the A

  7. Electron trajectories and growth rates of the plasma wave pumped free-electron laser

    Science.gov (United States)

    Jafari, S.; Jafarinia, F.; Nilkar, M.; Amiri, M.

    2014-12-01

    A theory for a plasma wave wiggler has been described which employs the plasma whistler wave for producing laser radiation in a free-electron laser (FEL). While electromagnetically pumped FELs have been proven to be an effective means generating short wavelengths, practical difficulties occur in the design of these wigglers. For this reason, it is found that a plasma wave wiggler can be employed in concept with an electromagnetic wave wiggler due to both higher tunability and holding the focus of pump wave and e-beam over a significant distance to achieve a suitable amplification. Plasma in the presence of static magnetic field supports a plasma whistler wave. The plasma wiggler period can be tuned by varying the plasma density and/or ambient magnetic field. Electron trajectories have been analyzed using single particle dynamics and regimes of orbital stability have been demonstrated. A polynomial dispersion relation for electromagnetic and space-charge waves has then been derived, analytically. Numerical studies of the dispersion relation reveal that the growth rates are sensitive functions of the cyclotron frequency. It has been shown that by increasing the axial magnetic field strength (or cyclotron frequency), the growth rate for groups I and III orbits increases, while a growth decrement has been obtained for groups II and IV orbits.

  8. Two-dimensional cylindrical ion-acoustic solitary and rogue waves in ultrarelativistic plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ata-ur-Rahman [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Centre for Physics at QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Centre for Physics at QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt); Mushtaq, A. [National Centre for Physics at QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Department of Physics, Abdul Wali Khan University, Mardan 23200 (Pakistan)

    2013-07-15

    The propagation of ion-acoustic (IA) solitary and rogue waves is investigated in a two-dimensional ultrarelativistic degenerate warm dense plasma. By using the reductive perturbation technique, the cylindrical Kadomtsev–Petviashvili (KP) equation is derived, which can be further transformed into a Korteweg–de Vries (KdV) equation. The latter admits a solitary wave solution. However, when the frequency of the carrier wave is much smaller than the ion plasma frequency, the KdV equation can be transferred to a nonlinear Schrödinger equation to study the nonlinear evolution of modulationally unstable modified IA wavepackets. The propagation characteristics of the IA solitary and rogue waves are strongly influenced by the variation of different plasma parameters in an ultrarelativistic degenerate dense plasma. The present results might be helpful to understand the nonlinear electrostatic excitations in astrophysical degenerate dense plasmas.

  9. Gravitational radiation of a vibrating physical string as a model for the gravitational emission of an astrophysical plasma

    CERN Document Server

    Lewis, R A

    2014-01-01

    The vibrating string is a source of gravitational waves which requires novel computational techniques, based on the explicit construction of a conserved and renormalized (in a classical sense) energy-momentum tensor. The renormalization is necessary to take into account the effect of external constraints, which affect the emission considerably. Vibrating media offer in general a testing ground for reconciling conflicts between General Relativity and other branches of physics; however, constraints are absent in sources like the Weber bar, for which the standard covariant formalism for elastic bodies can also be applied. Our solution method is based on the linearized Einstein equations, but relaxes other usual assumptions like far-field approximation, spherical or plane wave symmetry, TT gauge and source without internal interference. The string solution is then adapted to give the radiation field of a transversal Alfven wave in a rarefied plasma, where the tension is produced by an external static magnetic fie...

  10. Dust acoustic solitary and shock waves in strongly coupled dusty plasmas with nonthermal ions

    Indian Academy of Sciences (India)

    Hamid Reza Pakzad; Kurosh Javidan

    2009-11-01

    The Korteweg–de Vries–Burgers (KdV–Burgers) equation and modified Korteweg–de Vries–Burgers equation are derived in strongly coupled dusty plasmas containing nonthermal ions and Boltzmann distributed electrons. It is found that solitary waves and shock waves can be produced in this medium. The effects of important parameters such as ion nonthermal parameter, temperature, density and velocity on the properties of shock waves and solitary waves are discussed.

  11. Investigation of Ionospheric Turbulence and Whistler Wave Interactions with Space Plasmas

    Science.gov (United States)

    2012-11-21

    GeoMagnetic Observatory System ( GMO ). We then have detection of HF heater-induced large plasma sheets, using MUIR radar and GPS satellites [Cohen et al...experiments. It is found that the heat wave fronts, which occurred in US, were plausible sources of free energy generating intense gravity waves and...that the heat wave fronts, which occurred in USA, were the plausible sources of free energy, generating intense gravity waves and triggering large

  12. The Plasma Wave Investigation (PWI) onboard the BepiColombo/MMO: First measurement of electric fields, electromagnetic waves, and radio waves around Mercury

    Science.gov (United States)

    Kasaba, Y.; Bougeret, J.-L.; Blomberg, L. G.; Kojima, H.; Yagitani, S.; Moncuquet, M.; Trotignon, J.-G.; Chanteur, G.; Kumamoto, A.; Kasahara, Y.; Lichtenberger, J.; Omura, Y.; Ishisaka, K.; Matsumoto, H.

    2010-01-01

    The BepiColombo Mercury Magnetospheric Orbiter (MMO) spacecraft includes the plasma and radio wave observation system called Plasma Wave Investigation (PWI). Since the receivers for electric field, plasma waves, and radio waves are not installed in any of the preceding spacecraft to Mercury, the PWI will provide the first opportunity for conducting in-situ and remote-sensing observations of electric fields, plasma waves, and radio waves in the Hermean magnetosphere and exosphere. These observations are valuable in studying structure, dynamics, and energy exchange processes in the unique magnetosphere of Mercury. They are characterized by the key words of the non-MHD environment and the peculiar interaction between the relatively large planet without ionosphere and the solar wind with high dynamic pressure. The PWI consists of three sets of receivers (EWO, SORBET, and AM 2P), connected to two sets of electric field sensors (MEFISTO and WPT) and two kinds of magnetic field sensors (LF-SC and DB-SC). The PWI will observe both waveforms and frequency spectra in the frequency range from DC to 10 MHz for the electric field and from 0.3 Hz to 640 kHz for the magnetic field. From 2008, we will start the development of the engineering model, which is conceptually consistent with the flight model design. The present paper discusses the significance and objectives of plasma/radio wave observations in the Hermean magnetosphere, and describes the PWI sensors, receivers and their performance as well as the onboard data processing.

  13. Trapped electron acceleration by a laser-driven relativistic plasma wave

    Science.gov (United States)

    Everett, M.; Lal, A.; Gordon, D.; Clayton, C. E.; Marsh, K. A.; Joshi, C.

    1994-04-01

    THE aim of new approaches for high-energy particle acceleration1 is to push the acceleration rate beyond the limit (~100 MeV m-1) imposed by radio-frequency breakdown in conventional accelerators. Relativistic plasma waves, having phase velocities very close to the speed of light, have been proposed2-6 as a means of accelerating charged particles, and this has recently been demonstrated7,8. Here we show that the charged particles can be trapped by relativistic plasma waves-a necessary condition for obtaining the maximum amount of energy theoretically possible for such schemes. In our experiments, plasma waves are excited in a hydrogen plasma by beats induced by two collinear laser beams, the difference in whose frequencies matches the plasma frequency. Electrons with an energy of 2 MeV are injected into the excited plasma, and the energy spectrum of the exiting electrons is analysed. We detect electrons with velocities exceeding that of the plasma wave, demonstrating that some electrons are 'trapped' by the wave potential and therefore move synchronously with the plasma wave. We observe a maximum energy gain of 28 MeV, corresponding to an acceleration rate of about 2.8 GeV m-1.

  14. Laser-driven Beat-Wave Current Drive in Dense Plasmas with Demo on CTIX

    Science.gov (United States)

    Liu, Fei; Horton, Robert; Hwang, David; Zhu, Ben; Evans, Russell; Hong, Sean; Hsu, Scott

    2010-11-01

    The ability to remotely generate plasma current in dense plasmas hanging freely in vacuum in voluminous amount without obstruction to diagnostics will greatly enhance our ability to study the physics of high energy density plasmas in strong magnetic fields. Plasma current can be generated through nonlinear beat-wave process by launching two intense electromagnetic waves into unmagnetized plasma. Beat-wave acceleration of electrons has been demonstrated in a low-density plasma using microwaves [1]. The proposed PLX experimental facility presently under construction at Los Alamos offers the opportunity to test the method at a density level scalable to the study of HED plasmas. For PLX beat-wave experiments, CO2 lasers will be used as pump waves due to their high power and tunability. For a typical PLX density ne=10^17cm-3, two CO2 lasers can be separately tuned to 9P(28) and 10P(20) to match the 2.84THz plasma frequency. The beat-wave demo experiment will be conducted on CTIX. The laser arrangement is being converted to two independent single lasers. Frequency-tuning methods, optics focusing system and diagnostics system will be discussed. The laser measurements and results of synchronization of two lasers will be presented, and scaling to PLX experiments will be given. [1] Rogers, J. H. and Hwang, D. Q., PRL. v68 p3877 (1992).

  15. Diagnostics of Femtosecond Laser-Plasmas Using Fundamental and Second Harmonic Emission

    Institute of Scientific and Technical Information of China (English)

    ZHAO Li-Zeng; ZHANG Ping; FENG Bao-Hua; WEI Zhi-Yi; ZHANG Jie

    2000-01-01

    By observing the fundamental and second harmonic emission from a plasma produced by a 150 fs, 5 mJ laser at 800nm, the electron temperature, the expansion speed and the scalelength of the plasma have been diagnosed. Moreover the polarization of the fundamental and second harmonic emission has been studied. This could be a useful diagnostic for modulation at the critical surface of the plasma.

  16. Microwave power coupling in a surface wave excited plasma

    CERN Document Server

    Kar, Satyananda; Kousaka, Hiroyuki

    2014-01-01

    In recent decades, different types of plasma sources have been used for various types of plasma processing, such as, etching and thin film deposition. The critical parameter for effective plasma processing is high plasma density. One type of high density plasma source is Microwave sheath-Voltage combination Plasma (MVP). In the present investigation, a better design of MVP source is reported, in which over-dense plasma is generated for low input microwave powers. The results indicate that the length of plasma column increases significantly with increase in input microwave power.

  17. Higher order contribution to the propagation characteristics of low frequency transverse waves in a dusty plasma

    Indian Academy of Sciences (India)

    A P Misra; A Roy Chowdhury; S N Paul

    2004-09-01

    Characteristic features of low frequency transverse wave propagating in a magnetised dusty plasma have been analysed considering the effect of dust-charge fluctuation. The distinctive behaviours of both the left circularly polarised and right circularly polarised waves have been exhibited through the analysis of linear and non-linear dispersion relations. The phase velocity, group velocity, and group travel time for the waves have been obtained and their propagation characteristics have been shown graphically with the variations of wave frequency, dust density and amplitude of the wave. The change in non-linear wave number shift and Faraday rotation angle have also been exhibited with respect to the plasma parameters. It is observed that the effects of dust particles are significant only when the higher order contributions are considered. This may be referred to as the `dust regime' in plasma.

  18. Plasma Instability and Wave Propagation in Gate-Controlled GaN Conduction Channels

    Science.gov (United States)

    Rudin, Sergey; Rupper, Greg

    2013-08-01

    The plasma wave in the conduction channel of a semiconductor heterostructure high electron mobility transistor (HEMT) can be excited at frequencies significantly higher than the cut-off frequency in a short channel device. The hydrodynamic model predicts a resonance response to applied harmonic signal at the plasma oscillation frequency. When either the ac voltage induced in the channel by the signal at the gate or the current applied at the drain or source contact are not very small, the plasma waves in the semiconductor channel will propagate as a shock wave. The device can be used either as a detector or a tunable source of terahertz range radiation. Using the parameters appropriate for the GaN channel we show that in both configurations the charge flow develops shock waves due to hydrodynamic nonlinearities. In a sufficiently wide channel the wave propagation separates into two or more different bands giving a two-dimensional structure to the waves.

  19. Measurement of Wave Electric Fields in Plasmas by Electro-Optic Probe

    CERN Document Server

    Nishiura, M; Mushiake, T; Kawazura, Y; Osawa, R; Fujinami, K; Yano, Y; Saitoh, H; Yamasaki, M; Kashyap, A; Takahashi, N; Nakatsuka, M; Fukuyama, A

    2016-01-01

    Electric field measurement in plasmas permits quantitative comparison between the experiment and the simulation in this study. An electro-optic (EO) sensor based on Pockels effect is demonstrated to measure wave electric fields in the laboratory magnetosphere of the RT-1 device with high frequency heating sources. This system gives the merits that electric field measurements can detect electrostatic waves separated clearly from wave magnetic fields, and that the sensor head is separated electrically from strong stray fields in circumference. The electromagnetic waves are excited at the double loop antenna for ion heating in electron cyclotron heated plasmas. In the air, the measured wave electric fields are in good absolute agreement with those predicted by the TASK/WF2 code. In inhomogeneous plasmas, the wave electric fields in the peripheral region are enhanced compared with the simulated electric fields. The potential oscillation of the antenna is one of the possible reason to explain the experimental resu...

  20. Solar Corona and plasma effects on Radio Frequency waves

    Science.gov (United States)

    Nkono, C.; Rosenblatt, P.; Dehant, V. M.

    2009-12-01

    Solar corona (plasma) effects on radio signal waves for three different frequency bands S (2.3 GHz), X (8.4 GHz), and Ka (32 GHz), currently used to track probes in the solar system, have been computed using different models of the total electron content (TEC) along the propagation path between the Earth and Mars. The Earth-Mars-Sun configuration has been obtained from the planetary ephemerides DE421 (using SPICE kernels) for the period from September 2004 to September 2006. This configuration is expressed as a function of the Sun-Earth-Probe (SEP) angles (the probe being in close orbit to Mars). We used the TEC values provided by the different models proposed in the literature in order to estimate the TEC along the propagation path (STEC, for Slant TEC). From these model-dependent STEC estimates, the time delay on the wave propagation as well as the associated frequency shift with a 10 seconds sampling time have been obtained for each of the three frequency bands. For the X-band mostly used in radio science, we have obtained estimates differing by up to several orders of magnitude due to the different STEC values derived from different models of TEC. For example, if the propagation path passes near the Sun such that SEP angle is 1.55° the STEC is ranging from 4.6x1020 electron/m2 to 6.07x1016 electron/m2, which corresponds to a time delay range between 0.87 μs and 1.15x10-4 μs, respectively. For SEP angles between 2° and 8°, the range of the different time delay values reduces to 2.8x10-1 μs and becomes as small as 1.6x10-2 μs for SEP angles larger than 8° (1x10-2 μs is about the order of magnitude of the radioscience instrument precision). These results show that the correction of the solar corona effect on radio frequency waves can be reliably done on usual X-band tracking data of spacecraft for SEP angles >12°, but should be use with caution for lower SEP angles, especially lower than 2°.

  1. Existence of a virtual cathode close to a strongly electron emissive wall in low density plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Tierno, S. P., E-mail: sp.tierno@upm.es; Donoso, J. M.; Domenech-Garret, J. L.; Conde, L. [Department of Applied Physics, E.T.S.I. Aeronáutica y del Espacio. Universidad Politécnica de Madrid, 28040 Madrid (Spain)

    2016-01-15

    The interaction between an electron emissive wall, electrically biased in a plasma, is revisited through a simple fluid model. We search for realistic conditions of the existence of a non-monotonic plasma potential profile with a virtual cathode as it is observed in several experiments. We mainly focus our attention on thermionic emission related to the operation of emissive probes for plasma diagnostics, although most conclusions also apply to other electron emission processes. An extended Bohm criterion is derived involving the ratio between the two different electron densities at the potential minimum and at the background plasma. The model allows a phase-diagram analysis, which confirms the existence of the non-monotonic potential profiles with a virtual cathode. This analysis shows that the formation of the potential well critically depends on the emitted electron current and on the velocity at the sheath edge of cold ions flowing from the bulk plasma. As a consequence, a threshold value of the governing parameter is required, in accordance to the physical nature of the electron emission process. The latter is a threshold wall temperature in the case of thermionic electrons. Experimental evidence supports our numerical calculations of this threshold temperature. Besides this, the potential well becomes deeper with increasing electron emission, retaining a fraction of the released current which limits the extent of the bulk plasma perturbation. This noninvasive property would explain the reliable measurements of plasma potential by using the floating potential method of emissive probes operating in the so-called strong emission regime.

  2. Landau damping of the dust-acoustic surface waves in a Lorentzian dusty plasma slab

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myoung-Jae [Department of Physics and Research Institute for Natural Sciences, Hanyang University, Seoul 04763 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588 (Korea, Republic of); Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180-3590 (United States)

    2016-01-15

    Landau damping of a dust-acoustic surface wave propagating at the interfaces of generalized Lorentzian dusty plasma slab bounded by a vacuum is kinetically derived as the surface wave displays the symmetric and the anti-symmetric mode in a plasma slab. In the limiting case of small scaled wave number, we have found that Landau damping is enhanced as the slab thickness is increased. In particular, the damping of anti-symmetric mode is much stronger for a Lorentzian plasma than for a Maxwellian plasma. We have also found that the damping is more affected by superthermal particles in a Lorentzian plasma than by a Maxwellian plasma for both of the symmetric and the anti-symmetric cases. The variations of Landau damping with various parameters are also discussed.

  3. The impact of magnetic geometry on wave modes in cylindrical plasmas

    CERN Document Server

    Chang, Lei

    2015-01-01

    Both space and laboratory plasmas can be associated with static magnetic field, and the field geometry varies from uniform to non-uniform. This thesis investigates the impact of magnetic geometry on wave modes in cylindrical plasmas. The cylindrical configuration is chosen so as to explore this impact in a tractable but experimentally realisable configuration. Three magnetic geometries are considered: uniform, focused and rippled. These studies suggest suppressing drift waves in a uniformly magnetised plasma by increasing the field strength, enhancing the efficiency of helicon wave production of plasma by using a focused magnetic field, and forming a gap eigenmode on a linear plasma device by introducing a local defect to the system's periodicity, which is useful for understanding the gap-mode formation and interaction with energetic particles in fusion plasmas.

  4. Generation of powerful terahertz emission in a beam-driven strong plasma turbulence

    OpenAIRE

    Arzhannikov, A.V.; Timofeev, I. V.

    2012-01-01

    Generation of terahertz electromagnetic radiation due to coalescence of upper-hybrid waves in the long-wavelength region of strong plasma turbulence driven by a high-current relativistic electron beam in a magnetized plasma is investigated. The width of frequency spectrum as well as angular characteristics of this radiation for various values of plasma density and turbulence energy are calculated using the simple theoretical model adequately describing beam-plasma experiments at mirror traps....

  5. Nonlocal wave turbulence in non-Abelian plasmas

    CERN Document Server

    Mehtar-Tani, Yacine

    2016-01-01

    We investigate driven wave turbulence in non-Abelian plasmas, in the framework of kinetic theory where both elastic and inelastic processes are considered in the small angle approximation. The gluon spectrum, that forms in the presence of a steady source, is shown to be controlled by nonlocal interactions in momentum space, in contrast to the universal Kolmogorov-Zakharov spectra. Assuming strongly nonlocal interactions, we show that inelastic processes are dominant in the IR and cause a thermal bath to form below the forcing scale, as a result of a detailed balance between radiation and absorption of soft gluons by the hard ones. Above the forcing scale, the inelastic collision term reduces to an inhomogeneous diffusion-like equation yielding a spectrum that spreads to the UV as $t^{1/2}$, similarly to elastic processes. Due to nonlocal interactions the non-universal turbulent spectrum is not steady and flattens when time goes on toward the thermal distribution. This analysis is complemented by numerical sim...

  6. Sound waves and resonances in electron-hole plasma

    Science.gov (United States)

    Lucas, Andrew

    2016-06-01

    Inspired by the recent experimental signatures of relativistic hydrodynamics in graphene, we investigate theoretically the behavior of hydrodynamic sound modes in such quasirelativistic fluids near charge neutrality, within linear response. Locally driving an electron fluid at a resonant frequency to such a sound mode can lead to large increases in the electrical response at the edges of the sample, a signature, which cannot be explained using diffusive models of transport. We discuss the robustness of this signal to various effects, including electron-acoustic phonon coupling, disorder, and long-range Coulomb interactions. These long-range interactions convert the sound mode into a collective plasmonic mode at low frequencies unless the fluid is charge neutral. At the smallest frequencies, the response in a disordered fluid is quantitatively what is predicted by a "momentum relaxation time" approximation. However, this approximation fails at higher frequencies (which can be parametrically small), where the classical localization of sound waves cannot be neglected. Experimental observation of such resonances is a clear signature of relativistic hydrodynamics, and provides an upper bound on the viscosity of the electron-hole plasma.

  7. Experimental verification of directional liquid surface wave emission at band edge frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhenyu, E-mail: wzyu@zju.edu.cn; Zhang, Pei; Zhang, Yongqiang; Nie, Xiaofei

    2013-12-15

    Directional liquid surface wave emission at band edge frequencies is an interesting physical phenomenon and has already been studied in theoretical research. There has been no experimental validation of it to date, however. This paper has as its subject the experimental investigation of the emission effect when a point source is placed inside a finite square array of rigid cylinders standing vertically in liquid. Both the wave patterns and spatial intensities are obtained by experiment and compared with simulated results calculated by using the finite element method. We can see from this comparison that the two results correspond closely both at lower and upper band edge frequency. Obvious directional wave emission along a desired direction is observed in the source structures, confirming previous theoretical predictions. In the future, this method could serve as a directional liquid wave source in applications used in hydraulic and ocean engineering for the concentration of wave energy.

  8. Does the schock wave in a highly ionized non-isothermal plasma really exist ?

    CERN Document Server

    Rukhadze, A A; Samkharadze, T

    2015-01-01

    Here we study the structure of a highly ionizing shock wave in a gas of high atmospheric pressure. We take into account the gas ionization when the gas temperature reaches few orders of an ionization potential. It is shown that after gasdynamic temperature-raising shock and formation of a highly-ionized nonisothermal plasma $T_e>>T_i$ only the solitary ion-sound wave (soliton) can propagate in this plasma. In such a wave the charge separation occurs: electrons and ions form the double electric layer with the electric field. The shock wave form, its amplitude and front width are obtained.

  9. Estimation of emission cone wall thickness of Jupiter's decametric radio emission using stereoscopic STEREO/WAVES observations

    Science.gov (United States)

    Panchenko, M.; Rucker, H. O.

    2016-11-01

    Aims: Stereoscopic observations by the WAVES instrument onboard two STEREO spacecraft have been used with the aim of estimating wall thickness of an emission cone of Jovian decametric radio emission (DAM). Methods: Stereoscopic observations provided by STEREO-A and -B facilitate unambiguous recognition of the Jovian DAM in observed dynamic spectra as well as identification of its components (Io DAM or non-Io DAM). The dynamic spectra of radio emissions recorded by STEREO/WAVES have been analyzed using the method of cross-correlation of the radio dynamic spectra. Results: Altogether, 139 radio events, in particular 91 Io- and 48 non-Io-related radio events were observed. The averaged width of the emission cone wall for Io-DAM as well as for non-Io DAM is about 1.1° ± 0.2°. These results are in agreement with previous findings.

  10. EM wave propagation analysis in plasma covered radar absorbing material

    CERN Document Server

    Singh, Hema; Rawat, Harish Singh

    2017-01-01

    This book focuses on EM propagation characteristics within multilayered plasma-dielectric-metallic media. The method used for analysis is impedance transformation method. Plasma covered radar absorbing material is approximated as a multi-layered dielectric medium. The plasma is considered to be bounded homogeneous/inhomogeneous medium. The reflection coefficient and hence return loss is analytically derived. The role of plasma parameters, such as electron density, collision frequency, plasma thickness, and plasma density profile in the absorption behavior of multi-layered plasma-RAM structure is described. This book provides a clearer picture of EM propagation within plasma. The reader will get an insight of plasma parameters that play significant role in deciding the absorption characteristics of plasma covered surfaces.

  11. The use of laser-induced shock wave plasma spectroscopy (LISPS) for examining physical characteristics of pharmaceutical products

    Energy Technology Data Exchange (ETDEWEB)

    Abdulmadjid, Syahrun Nur, E-mail: syahrun-madjid@yahoo.com; Lahna, Kurnia, E-mail: kurnialahna@gmail.com [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, Aceh (Indonesia); Desiyana, Lydia Septa, E-mail: lydia-septa@yahoo.com [Department of Pharmacy, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, Aceh (Indonesia)

    2016-03-11

    An experimental study has been performed to examine the physical characteristics of pharmaceutical products, such as tablet, by employing an emission plasma induced by Nd-YAG laser at a low pressure of Helium gas. The hardness of tablet is one of the parameters that examined during the production process for standard quality of pharmaceutical products. In the Laser-Induced Shock Wave Plasma Spectroscopy (LISPS), the shock wave has a significant role in inducing atomic excitation. It was known that, the speed of the shock wavefront depends on the hardness of the sample, and it correlates with the ionization rate of the ablated atoms. The hardness of the tablet is examined using the intensity ratio between the ion of Mg (II) 275.2 nm and the neutral of Mg (I) 285.2 nm emission lines detected from the laser-induced plasma. It was observed that the ratio changes with respect to the change in the tablet hardness, namely the ratio is higher for the hard tablet. Besides the ratio measurements, we also measured the depth profile of a tablet by focusing 60 shots of irradiation of laser light at a fixed position on the surface of the tablet. It was found that the depth profile varies differently with the hardness of the tablet. These experiment results show that the technique of LISPS can be applied to examine the quality of pharmaceutical products.

  12. Resonance between heat-carrying electrons and Langmuir waves in inertial confinement fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Rozmus, W. [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2G7 (Canada); Chapman, T.; Berger, R. L. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Brantov, A.; Bychenkov, V. Yu. [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow 119991 Russia and Center for Fundamental and Applied Research, VNIIA, ROSATOM, 127055 Moscow (Russian Federation); Winjum, B. J. [Department of Electrical Engineering, UCLA, Los Angeles, California 90095 (United States); Brunner, S. [Association EURATOM-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland); Tableman, A.; Tzoufras, M. [Department of Physics and Astronomy, UCLA, Los Angeles, California 90095 (United States); Glenzer, S. [LCLS, Stanford, California 94025 (United States)

    2016-01-15

    In ignition scale hot plasmas, temperature gradients and thermal transport modify electron distributions in a velocity range resonant with Langmuir waves typical of those produced by stimulated Raman scattering. We examine the resultant changes to the Landau damping experienced by these Langmuir waves and the levels of thermal plasma fluctuations. The form factor and Thomson scattering cross-section in such plasmas display unique characteristics of the background conditions. A theoretical model and high-order Vlasov-Fokker-Planck simulations are used in our analysis. An experiment to measure changes in thermal plasma fluctuation levels due to a thermal gradient is proposed.

  13. Analysis of the axial electric field in a plasma-loaded-helix travelling wave tube

    Institute of Scientific and Technical Information of China (English)

    Xie Hong-Quan; Liu Pu-Kun

    2006-01-01

    A helix type slow wave structure filled with plasma is immersed in a strong longitudinal magnetic field. Taking into account the effect of the plasma and the dielectric, the system is separated radially into three regions. By means of the sheath model and Maxwell equation, the distribution of the electromagnetic field is established. Using the boundary conditions of each region, the dispersion relation of the slow wave structure is derived. The trend of change for the radial profile of the axial electric field is analysed respectively in different plasma densities, plasma column radius and dielectric constant by numerical computation. Some useful results are obtained on the basis of the discussion.

  14. Secondary electron emission from plasma processed accelerating cavity grade niobium

    Science.gov (United States)

    Basovic, Milos

    Advances in the particle accelerator technology have enabled numerous fundamental discoveries in 20th century physics. Extensive interdisciplinary research has always supported further development of accelerator technology in efforts of reaching each new energy frontier. Accelerating cavities, which are used to transfer energy to accelerated charged particles, have been one of the main focuses of research and development in the particle accelerator field. Over the last fifty years, in the race to break energy barriers, there has been constant improvement of the maximum stable accelerating field achieved in accelerating cavities. Every increase in the maximum attainable accelerating fields allowed for higher energy upgrades of existing accelerators and more compact designs of new accelerators. Each new and improved technology was faced with ever emerging limiting factors. With the standard high accelerating gradients of more than 25 MV/m, free electrons inside the cavities get accelerated by the field, gaining enough energy to produce more electrons in their interactions with the walls of the cavity. The electron production is exponential and the electron energy transfer to the walls of a cavity can trigger detrimental processes, limiting the performance of the cavity. The root cause of the free electron number gain is a phenomenon called Secondary Electron Emission (SEE). Even though the phenomenon has been known and studied over a century, there are still no effective means of controlling it. The ratio between the electrons emitted from the surface and the impacting electrons is defined as the Secondary Electron Yield (SEY). A SEY ratio larger than 1 designates an increase in the total number of electrons. In the design of accelerator cavities, the goal is to reduce the SEY to be as low as possible using any form of surface manipulation. In this dissertation, an experimental setup was developed and used to study the SEY of various sample surfaces that were treated

  15. Secondary Electron Emission from Plasma Processed Accelerating Cavity Grade Niobium

    Energy Technology Data Exchange (ETDEWEB)

    Basovic, Milos [Old Dominion Univ., Norfolk, VA (United States)

    2016-05-01

    Advances in the particle accelerator technology have enabled numerous fundamental discoveries in 20th century physics. Extensive interdisciplinary research has always supported further development of accelerator technology in efforts of reaching each new energy frontier. Accelerating cavities, which are used to transfer energy to accelerated charged particles, have been one of the main focuses of research and development in the particle accelerator field. Over the last fifty years, in the race to break energy barriers, there has been constant improvement of the maximum stable accelerating field achieved in accelerating cavities. Every increase in the maximum attainable accelerating fields allowed for higher energy upgrades of existing accelerators and more compact designs of new accelerators. Each new and improved technology was faced with ever emerging limiting factors. With the standard high accelerating gradients of more than 25 MV/m, free electrons inside the cavities get accelerated by the field, gaining enough energy to produce more electrons in their interactions with the walls of the cavity. The electron production is exponential and the electron energy transfer to the walls of a cavity can trigger detrimental processes, limiting the performance of the cavity. The root cause of the free electron number gain is a phenomenon called Secondary Electron Emission (SEE). Even though the phenomenon has been known and studied over a century, there are still no effective means of controlling it. The ratio between the electrons emitted from the surface and the impacting electrons is defined as the Secondary Electron Yield (SEY). A SEY ratio larger than 1 designates an increase in the total number of electrons. In the design of accelerator cavities, the goal is to reduce the SEY to be as low as possible using any form of surface manipulation. In this dissertation, an experimental setup was developed and used to study the SEY of various sample surfaces that were treated

  16. Acceleration of energetic electrons by waves in inhomogeneous solar wind plasmas

    Science.gov (United States)

    Krafft, C.; Volokitin, A.

    2017-04-01

    The paper studies the influence of the background plasma density fluctuations on the dynamics of the Langmuir turbulence generated by electron beams, for parameters typical for solar type III beams and plasmas near 1 AU. A self-consistent Hamiltonian model based on the Zakharov and the Newton equations is used, which presents several advantages compared to the Vlasov approach. Beams generating Langmuir turbulence can be accelerated as a result of wave transformation effects or/and decay cascade processes; in both cases, the beam-driven Langmuir waves transfer part of their energy to waves of smaller wavenumbers, which can be reabsorbed later on by beam particles of higher velocities. As a consequence, beams can conserve a large part of their initial kinetic energy while propagating and radiating wave turbulence over long distances in inhomogeneous plasmas. Beam particles can also be accelerated in quasi-homogeneous plasmas due to the second cascade of wave decay, the wave transformation processes being very weak in this case. The net gains and losses of energy of a beam and the wave turbulence it radiates are calculated as a function of the average level of plasma density fluctuations and the beam parameters. The results obtained provide relevant information on the mechanism of energy reabsorption by beams radiating Langmuir turbulence in solar wind plasmas.

  17. Wave and plasma measurements and GPS diagnostics of the main ionospheric trough as a hybrid method used for Space Weather purposes

    Directory of Open Access Journals (Sweden)

    H. Rothkaehl

    2008-02-01

    Full Text Available The region of the main ionospheric trough is a unique region of the ionosphere, where different types of waves and instabilities can be generated. This region of the ionosphere acts like a lens, focusing a variety of indicators from the equator of plasmapause and local ionospheric plasma. This paper reports the results of monitoring the mid-latitude trough structure, dynamics and wave activity. For these purposes, the data gathered by the currently-operating DEMETER satellite and past diagnostics located on IK-19, Apex, and MAGION-3 spacecraft, as well as TEC measurements were used. A global-time varying picture of the ionospheric trough was reconstructed using the sequence of wave spectra registered and plasma measurements in the top-side ionosphere. The authors present the wave activity from ULF frequency band to the HF frequency detected inside the trough region and discuss its properties during geomagnetic disturbances. It is thought that broadband emissions are correlated with low frequency radiation, which is excited by the wave-particle interaction in the equatorial plasmapause and moves to the ionosphere along the geomagnetic field line. In the ionosphere, the suprathermal electrons can interact with these electrostatic waves and excite electron acoustic waves or HF longitudinal plasma waves.

    Furthermore, the electron density trough can provide useful data on the magnetosphere ionosphere dynamics and morphology and, in consequence, can be used for Space Weather purposes.

  18. Low Frequency Turbulence as the Source of High Frequency Waves in Multi-Component Space Plasmas

    Science.gov (United States)

    Khazanov, George V.; Krivorutsky, Emmanuel N.; Uritsky, Vadim M.

    2011-01-01

    Space plasmas support a wide variety of waves, and wave-particle interactions as well as wavewave interactions are of crucial importance to magnetospheric and ionospheric plasma behavior. High frequency wave turbulence generation by the low frequency (LF) turbulence is restricted by two interconnected requirements: the turbulence should be strong enough and/or the coherent wave trains should have the appropriate length. These requirements are strongly relaxed in the multi-component plasmas, due to the heavy ions large drift velocity in the field of LF wave. The excitation of lower hybrid waves (LHWs), in particular, is a widely discussed mechanism of interaction between plasma species in space and is one of the unresolved questions of magnetospheric multi-ion plasmas. It is demonstrated that large-amplitude Alfven waves, in particular those associated with LF turbulence, may generate LHW s in the auroral zone and ring current region and in some cases (particularly in the inner magnetosphere) this serves as the Alfven wave saturation mechanism. We also argue that the described scenario can playa vital role in various parts of the outer magnetosphere featuring strong LF turbulence accompanied by LHW activity. Using the data from THEMIS spacecraft, we validate the conditions for such cross-scale coupling in the near-Earth "flow-braking" magnetotail region during the passage of sharp injection/dipolarization fronts, as well as in the turbulent outflow region of the midtail reconnection site.

  19. Modulational instability of plasma waves in two dimensions

    DEFF Research Database (Denmark)

    Karpman, V.I.; Lynov, Jens-Peter; Michelsen, Poul

    1996-01-01

    The nonlinear behavior of whistler waves coupled to either fast magnetosonic waves (FMS) or slow magnetosonic waves (SMS) is investigated in two spatial dimensions. For each branch our investigation is based on a numerical solution of a reduced set of equations consisting of two partial...... differential equations, of which one, describing the evolution of the whistler wave envelope, is complex of first order in time and the other, describing the slow response of the medium in which the whistler wave is propagating, is real and of second order in time. These equations were solved in a two...... of nonlinear waves in dispersive media....

  20. Kinetic full wave analyses of O-X-B mode conversion of EC waves in tokamak plasmas

    Science.gov (United States)

    Fukuyama, Atsushi; Khan, Shabbir Ahmad; Igami, Hiroe; Idei, Hiroshi

    2016-10-01

    For heating and current drive in a high-density plasma of tokamak, especially spherical tokamak, the use of electron Bernstein waves and the O-X-B mode conversion were proposed and experimental observations have been reported. In order to evaluate the power deposition profile and the current drive efficiency, kinetic full wave analysis using an integral form of dielectric tensor has been developed. The incident angle dependence of wave structure and O-X-B mode conversion efficiency is examined using one-dimensional analysis in the major radius direction. Two-dimensional analyses on the horizontal plane and the poloidal plane are also conducted, and the wave structure and the power deposition profile are compared with those of previous analyses using ray tracing method and cold plasma approximation. This work is supported by JSPS KAKENHI Grant Number JP26630471.

  1. Emission characteristics of kerosene-air spray combustion with plasma assistance

    Directory of Open Access Journals (Sweden)

    Xingjian Liu

    2015-09-01

    Full Text Available A plasma assisted combustion system for combustion of kerosene-air mixtures was developed to study emission levels of O2, CO2, CO, and NOx. The emission measurement was conducted by Testo 350-Pro Flue Gas Analyzer. The effect of duty ratio, feedstock gas flow rate and applied voltage on emission performance has been analyzed. The results show that O2 and CO emissions reduce with an increase of applied voltage, while CO2 and NOx emissions increase. Besides, when duty ratio or feedstock gas flow rate decreases, the same emission results would appear. The emission spectrum of the air plasma of plasma assisted combustion actuator was also registered to analyze the kinetic enhancement effect of plasma, and the generation of ozone was believed to be the main factor that plasma makes a difference in our experiment. These results are valuable for the future optimization of kerosene-fueled aircraft engine when using plasma assisted combustion devices to exert emission control.

  2. Electron temperature fluctuation in the HT-7 tokamak plasma observed by electron cyclotron emission imaging

    Institute of Scientific and Technical Information of China (English)

    Xu Xiao-Yuan; Wang Jun; Yu Yi; Wen Yi-Zhi; Yu Chang-Xuan; Liu Wan-Dong; Wan Bao-Nian; Gao Xiang; N. C. Luhmann; C. W. Domier; Jian Wang; Z. G. Xia; Zuowei Shen

    2009-01-01

    The fluctuation of the electron temperature has been measured by using the electron cyclotron emission imaging in the Hefei Tokamak-7 (HT-7) plasma. The electron temperature fluctuation with a broadband spectrum shows that it propagates in the electron diamagnetic drift direction, and the mean poloidal wave-number kg is calculated to be about 1.58 cm-1, or keps ≈0.34. It indicates that the fluctuation should come from the electron drift wave turbulence. The linear global scaling of the electron temperature fluctuation with the gradient of electron temperature is consistent with the mixing length scale qualitatively. Evolution of spectrum of the fluctuation during the sawtooth oscillation phases is investigated, and the fluctuation is found to increase with the gradient of electron temperature increasing during most phases of the sawtooth oscillation. The results indicate that the electron temperature gradient is probably the driver of the fluctuation enhancement. The steady heat flux driven by electron temperature fluctuation is estimated and compared with the results from power balance estimation.

  3. Laser-Driven Ultra-Relativistic Plasmas - Nuclear Fusion in Coulomb Shock Waves, Rouge Waves, and Background Matter

    Science.gov (United States)

    2015-05-05

    AND SUBTITLE LASER-DRIVEN ULTRA-RELATIVISTIC PLASMAS - NUCLEAR FUSION IN COULOMB SHOCK WAVES, ROUGE WAVES, AND BACKGROUND MATTER. 5a.  CONTRACT...blackbody radiation on free electrons .........................9 2.vi. Proposal of ultimate test of laser nuclear fusion efficiency in clusters...domain of energies and temperatures, with applications in particular to controlled nuclear fusion . 2. Final technical report on the grant #F49620-11-1

  4. Alfven Wave Collisions, The Fundamental Building Block of Plasma Turbulence IV: Laboratory Experiment

    CERN Document Server

    Drake, D J; Howes, G G; Kletzing, C A; Skiff, F; Carter, T A; Auerbach, D W

    2013-01-01

    Turbulence is a phenomenon found throughout space and astrophysical plasmas. It plays an important role in solar coronal heating, acceleration of the solar wind, and heating of the interstellar medium. Turbulence in these regimes is dominated by Alfven waves. Most turbulence theories have been established using ideal plasma models, such as incompressible MHD. However, there has been no experimental evidence to support the use of such models for weakly to moderately collisional plasmas which are relevant to various space and astrophysical plasma environments. We present the first experiment to measure the nonlinear interaction between two counterpropagating Alfven waves, which is the building block for astrophysical turbulence theories. We present here four distinct tests that demonstrate conclusively that we have indeed measured the daughter Alfven wave generated nonlinearly by a collision between counterpropagating Alfven waves.

  5. A New Look at the Landau's Theory of Spreading and Damping of Waves in Collisionless Plasmas

    CERN Document Server

    Soshnikov, V N

    2008-01-01

    The theory of plasma waves and Landau damping in Maxwellian plasmas, Landau's ``rule of pass around poles'' include doubtful statements, particularly related to an artificial ``constructing'' of the dispersion equation, what should allow the possibility of its solution otherwise not existing at all, and the possibility of analytical continuations of corresponding very specific ruptured functions in the one-dimensional Laplace transformation, used by Landau, what is the base of his theory. We represent, as an accessible variant, a more general alternative theory based on a two-dimensional Laplace transformation, leading to an asymptotical in time and space solution as a complicated superposition of coupled damping and {\\em non-damping \\/} plane waves and oscillations with different dispersion laws for every constituent mode. This theory naturally and very simply explains paradoxes of the phenomenon of plasma echo. We propose for discussion a new ideology of plasma waves (both electron and ion-acoustic waves) q...

  6. Propagation of electromagnetic waves through magnetized plasmas in arbitrary gravitational fields

    OpenAIRE

    Breuer, R; Ehlers, J.

    1981-01-01

    A generalized JWBK-method for high-frequency waves traveling through inhomogeneous, moving plasmas imbedded in arbitrary relativistic gravitational fields is reported. In particular, a generalization of the standard formula for Faraday rotation is given.

  7. Theoretical analysis of a relativistic travelling wave tube filled with plasma

    Institute of Scientific and Technical Information of China (English)

    Xie Hong-Quan; Liu Pu-Kun

    2007-01-01

    A cold and uniform plasma-filled travelling wave tube with sinusoidally corrugated slow wave structure is driven by a finite thick annular intense relal:ivistic electron beam with the entire system immersed in a strong longitudinal magnetic field.By means of the linear field theory,the dispersion relation for the relativistic travelling wave tube (RTWT) is derived.By numerical computation,the dispersion characteristics of the RTWT are analysed in difierent cases of various geometric parameters of the slow wave structure and plasma densities.Also the gain versus frequency for three difierent plasma densities and the peak gain of the tube versus plasma density are analysed.Some useful results are obtained on the basis of the discussion.

  8. Stimulated Brillouin scattering of an electromagnetic wave in weakly magnetized plasma with variably charged dust particles

    Indian Academy of Sciences (India)

    Sourabh Bal; M Bose

    2009-10-01

    We have investigated analytically the stimulated Brillouin scattering (SBS) of an electromagnetic wave in non-dissipative weakly magnetized plasma in the presence of dust particles with variable charge.

  9. Linear and nonlinear dynamics of current-driven waves in dusty plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Ali [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology (CIIT), Islamabad (Pakistan); Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Ali Shan, S.; Haque, Q. [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Saleem, H. [National Centre for Physics (NCP), Shahdara Valley Road, 44000 Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology (CIIT), Islamabad (Pakistan)

    2012-09-15

    The linear and nonlinear dynamics of a recently proposed plasma mode of dusty plasma is studied using kappa distribution for electrons. This electrostatic wave can propagate in the plasma due to the sheared flow of electrons and ions parallel to the external magnetic field in the presence of stationary dust. The coupling of this wave with the usual drift wave and ion acoustic wave is investigated. D'Angelo's mode is also modified in the presence of superthermal electrons. In the nonlinear regime, the wave can give rise to dipolar vortex structures if the shear in flow is weaker and tripolar vortices if the flow has steeper gradient. The results have been applied to Saturn's magnetosphere corresponding to negatively charged dust grains. But the theoretical model is applicable for positively charged dust as well. This work will be useful for future observations and studies of dusty environments of planets and comets.

  10. Ion acoustic kinetic Alfvén rogue waves in two temperature electrons superthermal plasmas

    Science.gov (United States)

    Kaur, Nimardeep; Saini, N. S.

    2016-10-01

    The propagation properties of ion acoustic kinetic Alfvén (IAKA) solitary and rogue waves have been investigated in two temperature electrons magnetized superthermal plasma in the presence of dust impurity. A nonlinear analysis is carried out to derive the Korteweg-de Vries (KdV) equation using the reductive perturbation method (RPM) describing the evolution of solitary waves. The effect of various plasma parameters on the characteristics of the IAKA solitary waves is studied. The dynamics of ion acoustic kinetic Alfvén rogue waves (IAKARWs) are also studied by transforming the KdV equation into nonlinear Schrödinger (NLS) equation. The characteristics of rogue wave profile under the influence of various plasma parameters (κc, μc, σ , θ) are examined numerically by using the data of Saturn's magnetosphere (Schippers et al. 2008; Sakai et al. 2013).

  11. Microwave beatwave excitation of electron plasma wave and high energy electron production

    Energy Technology Data Exchange (ETDEWEB)

    Yatsuzuka, M.; Obata, K.; Nobuhara, S. [Himeji Inst. of Tech., Hyogo (Japan)

    1997-12-31

    Two X-band microwave beams with a slightly different frequency and the maximum output power of 50 kW are injected into a target plasma antiparallel to each other through a standard horn. The resonant excitation of an electron plasma wave is observed when the difference in frequency between counterstreaming microwaves is equal to the electron plasma frequency. The excited wave propagates in the same direction as the higher-frequency microwave with a wave length which satisfies the resonance condition of wave number. The wave amplitude grows with an increase in incident microwave power, and reaches the density perturbation {delta}n/n{sub 0} of approximately 3.2 % at the incident microwave power of 40 kW and beat frequency of 600 MHz. A small amount of high-energy electrons with the speed of 27 eV are observed in the high-power region of incident microwave. (author)

  12. Enhanced Plasma Confinement in a Magnetic Well by Whistler Waves

    DEFF Research Database (Denmark)

    Balmashnov, A. A.; Juul Rasmussen, Jens

    1981-01-01

    The propagation of whistler waves in a magnetic field of mirror configuration is investigated experimentally. The strong interaction between waves and particles at the electron-cyclotron resonance leads to enhanced confinement in the magnetic well.......The propagation of whistler waves in a magnetic field of mirror configuration is investigated experimentally. The strong interaction between waves and particles at the electron-cyclotron resonance leads to enhanced confinement in the magnetic well....

  13. Characterisation of a micro-plasma device sensor using electrical measurements and emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mariotti, D

    2002-04-01

    This thesis reports on research undertaken on the characterisation of a micro-plasma device to be used for gas analysis by mean of plasma emission spectroscopy. The work covers aspects related to the micro-plasma electrical and optical emission parameters, and their importance for the utilisation of the micro-plasma device in gas analysis. Experimental results have been used to analyse the fundamental micro-plasma processes and to develop a model, which could provide additional information. This dissertation contains a general literature review of topics related to plasma physics, plasma emission spectroscopy, gas analysis (chemical analysis and artificial olfaction) and other micro-plasma applications. Experimental work focuses on two main areas: electrical measurements and emission measurements. Firstly, electrical measurements are taken and interpretations are given. Where necessary, new theoretical treatments are suggested in order to describe better the physical phenomena. Plasma emission has been considered under different working conditions. This allowed the characterisation of the micro-plasma emission and also a better understanding of the micro-plasma processes. On the basis of the experimental data obtained and other assumptions a model has been developed. A computer simulation based on this model provided additional useful information on the micro- plasma behaviour. The first fundamental implication of this new research is the peculiar behaviour of the micro-plasma. This micro-plasma exhibited deviations from Paschen law and strong dependency on cathode material, which contributed to the formation of a low current stable regime. These results have been followed by physical interpretations and theoretical descriptions. The second implication is the establishment of the boundaries and of the influencing parameters for plasma emission spectroscopy as an analytical tool in this particular micro-plasma. From the applied perspective this study has shown that

  14. Geometric Phase Of The Faraday Rotation Of Electromagnetic Waves In Magnetized Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jian Liu and Hong Qin

    2011-11-07

    The geometric phase of circularly polarized electromagnetic waves in nonuniform magnetized plasmas is studied theoretically. The variation of the propagation direction of circularly polarized waves results in a geometric phase, which also contributes to the Faraday rotation, in addition to the standard dynamical phase. The origin and properties of the geometric phase is investigated. The in uence of the geometric phase to plasma diagnostics using Faraday rotation is also discussed as an application of the theory.

  15. Alfvén wave coupled with flow-driven fluid instability in interpenetrating plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Vranjes, J. [Instituto de Astrofisica de Canarias, 38205 La Laguna, Tenerife, Spain and Departamento de Astrofisica, Universidad de La Laguna, 38205 La Laguna, Tenerife (Spain)

    2015-05-15

    The Alfvén wave is analyzed in case of one quasineutral plasma propagating with some constant speed v{sub 0} through another static quasineutral plasma. A dispersion equation is derived describing the Alfvén wave coupled with the flow driven mode ω=kv{sub 0} and solutions are discussed analytically and numerically. The usual solutions for two oppositely propagating Alfvén waves are substantially modified due to the flowing plasma. More profound is modification of the solution propagating in the negative direction with respect to the magnetic field and the plasma flow. For a large enough flow speed (exceeding the Alfvén speed in the static plasma), this negative solution may become non-propagating, with frequency equal to zero. In this case, it represents a spatial variation of the electromagnetic field. For greater flow speed it becomes a forward mode, and it may merge with the positive one. This merging of the two modes represents the starting point for a flow-driven instability, with two complex-conjugate solutions. The Alfvén wave in interpenetrating plasmas is thus modified and coupled with the flow-driven mode and this coupled mode is shown to be growing when the flow speed is large enough. The energy for the instability is macroscopic kinetic energy of the flowing plasma. The dynamics of plasma particles caused by such a coupled wave still remains similar to the ordinary Alfvén wave. This means that well-known stochastic heating by the Alfvén wave may work, and this should additionally support the potential role of the Alfvén wave in the coronal heating.

  16. Refined Study of ECR Wave Propagation and Absorption in the Weakly Relativistic Plasma

    Institute of Scientific and Technical Information of China (English)

    SHIBingren; LONGYongxin

    2001-01-01

    The ECR wave heating is now a routine method for plasma heating and profile control in fusion devices and also in plasma applications. Theoretical study of ECR wave propagation and absorption began very early in 1950's. Basic theoretical work had accomplished in 1970~1980. For toroidal devices like the tokamak, the fundamental O-mode and X-mode with nearly perpendicular propagation were used very often. For pure O-mode and X-mode with kx=O,

  17. Study on Propagation Characteristics of Plasma Surface Wave in Medium Tube

    Institute of Scientific and Technical Information of China (English)

    WANG Shiqing; YAN Zelin; LI Wenzhong; LIU Jian; LI Jian; XU Lingfei

    2008-01-01

    Axial propagation characteristics of the axisymmetric surface wave along the plasma in the medium tube were studied. The expressions of electromagnetic field inside and outside the medium tube were deduced. Also, the impacts of several factors, such as plasma density, signal frequency, inner radius of medium tube, collision frequency, etc., on plasma surface wave propa-gation were numerically simulated. The results show that, the properties of plasma with higher density and .lower gas pressure are closer to those of metal conductor. Furthermore, larger radius of medium tube and lower signal frequency are better for surface wave propagation. However, the effect of collision frequency is not obvious. The optimized experimental parameters can be chosen as the plasma density of about 1017 m-3 and the medium radius between 11 mm and 19 mm.

  18. Propagation of ion-acoustic solitary waves in a relativistic electron-positron-ion plasma

    CERN Document Server

    Saberian, E; Akbari-Moghanjoughi, M

    2011-01-01

    Propagation of large amplitude ion-acoustic solitary waves (IASWs) in a fully relativistic plasma consisting of cold ions and ultrarelativistic hot electrons and positrons is investigated using the Sagdeev's pseudopotential method in a relativistic hydrodynamics model. Effects of streaming speed of plasma fluid, thermal energy, positron density and positron temperature on large amplitude IASWs are studied by analysis of the pseudopotential structure. It is found that in regions that the streaming speed of plasma fluid is larger than that of solitary wave, by increasing the streaming speed of plasma fluid the depth and width of potential well increases and resulting in narrower solitons with larger amplitude. This behavior is opposite for the case where the streaming speed of plasma fluid is smaller than that of solitary wave. On the other hand, increase of the thermal energy results in wider solitons with smaller amplitude, because the depth and width of potential well decreases in that case. Additionally, th...

  19. Axisymmetric Nonlinear Waves And Structures in Hall Plasmas

    CERN Document Server

    Islam, Tanim

    2011-01-01

    A Hall plasma consists of a plasma with not all species frozen into the magnetic field. In this paper, a general equation for the evolution of an axisymmetric magnetic field in a Hall plasma is derived, with an integral similar to the Grad-Shafranov equation. Special solutions arising from curvature -- whistler drift modes that propagate along the electron drift as a Burger's shock, and nonlinear periodic and soliton-like solutions to the generalized Grad-Shafranov integral -- are analyzed. We derive analytical and numerical solutions in an electron-ion Hall plasma, in which electrons and ions are the only species in the plasmas. Results may then be applied to electron-ion-gas Hall plasmas, in which the ions are coupled to the motion of gases in low ionized plasmas (lower ionosphere and protostellar disks), and to dusty Hall plasmas (such as molecular clouds), in which the much heavier charged dust may be collisionally coupled to the gas.

  20. Pitch angle scattering by triggered emissions from the Siple Station wave injection experiment

    Science.gov (United States)

    Harid, V.; Golkowski, M.; Bell, T. F.; Cohen, M.; Inan, U. S.

    2012-12-01

    Nonlinear amplification of whistler mode waves in the Earth's magnetosphere , due to gyroresonance with energetic electrons, also known as the phenomena of VLF triggered emissions, has been investigated extensively with analytical formulations, experimental observations and computer simulations. However, the pitch angle scattering of typical triggered emission waveforms has not been specifically considered. Most authors consider particle scattering either in the presence of a monochromatic constant amplitude wave or a broadband incoherent but time-frequency homogenous emission. Although investigation of these two limiting cases has provided valuable insight into radiation belt dynamics, a large class of waves including triggered emissions and chorus do not fall under either of the two descriptions. The inherent symmetry of a constant amplitude monochromatic wave around the equator results in non-cumulative pitch angle change for a large population of electrons. Wave amplification generated during linear and nonlinear growth result in wave gradients that can have a more significant effect on particle pitch angle and energy. In addition, coherent frequency changing signals are capable of shifting the cyclotron resonance condition and significantly perturbing particle trajectories from their adiabatic motion. The wave-injection experiment at Siple Station, Antarctica was designed to study wave growth and triggering processes in the magnetosphere. Amplified signals from Siple Station often show both wave gradients as well advances in phase and frequency. Using a numerical test-particle simulation, we model the effect of typical Siple Station signals on pitch angle scattering and particle precipitation. Results show that triggered emission type wave forms are more efficient in producing large pitch angle changes in resonant particles.

  1. Comment on "Surface electromagnetic wave equations in a warm magnetized quantum plasma" [Phys. Plasmas 21, 072114 (2014)

    Science.gov (United States)

    Moradi, Afshin

    2016-07-01

    In a recent article [C. Li et al., Phys. Plasmas 21, 072114 (2014)], Li et al. studied the propagation of surface waves on a magnetized quantum plasma half-space in the Voigt configuration (in this case, the magnetic field is parallel to the surface but is perpendicular to the direction of propagation). Here, we present a fresh look at the problem and obtain a new form of dispersion relation of surface waves of the system. We find that our new dispersion relation does not agree with the result obtained by Li et al.

  2. 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...... 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 Eγ/EGW ... of the gravitational wave source, based on the available predictions for prompt electromagnetic emission....

  3. Nonlinear Alfvén Waves in a Vlasov Plasma

    DEFF Research Database (Denmark)

    Bell, T.F.

    1965-01-01

    Stationary solutions to the nonlinear Vlasov—Boltzmann equations are considered which represent one-dimensional electromagnetic waves in a hot magnetoplasma. These solutions appear in arbitrary reference frames as circularly polarized, sinusoidal waves of unlimited amplitude, i.e., as nonlinear...... Alfvén waves. Solutions are found implicitly by deriving a set of integral dispersion relations which link the wave characteristics with the particle distribution functions. A physical discussion is given of the way in which the Alfvén waves can trap particles, and it is shown that the presence...

  4. The structure of standing Alfvén waves in a dipole magnetosphere with moving plasma

    Directory of Open Access Journals (Sweden)

    D. A. Kozlov

    2006-03-01

    Full Text Available The structure and spectrum of standing Alfvén waves were theoretically investigated in a dipole magnetosphere with moving plasma. Plasma motion was simulated with its azimuthal rotation. The model's scope allowed for describing a transition from the inner plasmasphere at rest to the outer magnetosphere with convecting plasma and, through the magnetopause, to the moving plasma of the solar wind. Solutions were found to equations describing longitudinal and transverse (those formed, respectively, along field lines and across magnetic shells structures of standing Alfvén waves with high azimuthal wave numbers m>>1. Spectra were constructed for a number of first harmonics of poloidal and toroidal standing Alfvén waves inside the magnetosphere. For charged particles with velocities greatly exceeding the velocity of the background plasma, an effective parallel wave component of the electric field appears in the region occupied by such waves. This results in structured high-energy-particle flows and in the appearance of multiband aurorae. The transverse structure of the standing Alfvén waves' basic harmonic was shown to be analogous to the structure of a discrete auroral arc.

  5. Prepulse-induced shock waves in the gas jet target of a laser plasma EUV radiation source

    Science.gov (United States)

    Garbaruk, A. V.; Gritskevich, M. S.; Kalmykov, S. G.; Mozharov, A. M.; Sasin, M. E.

    2017-01-01

    In experiments with a laser-plasma EUV-radiation source, the main IR Nd:YAG laser pulse was preceded by that of a UV KrF excimer laser. Dramatic modulations of EUV plasma emissivity have been observed at long interpulse times, from hundreds of nanoseconds up to microseconds. To discover the nature of these prepulse-produced long-living perturbations of the target, a fluid dynamics numerical simulation of the Xe gas jet has been carried out. The prepulse has been found to generate a quasi-spherical shock wave with a thin dense front layer and a vast rarefied inside area. In the course of time, the front expands and simultaneously drifts downstream along with the gas. Depending on the interpulse time, the IR laser beam either intersects the dense layer or propagates within the rarefied gas cavity whereby the above-mentioned variations in the plasma emission can be explained. The possibilities of making use of the discovered phenomena to enhance the observed EUV plasma brightness are discussed.

  6. Observation of Hot Electrons in Surface-Wave Plasmas Excited by Surface Plasmon Polaritons

    Institute of Scientific and Technical Information of China (English)

    HU Ye-Lin; CHEN Zhao-Quan; LIU Ming-Hai; HONG Ling-Li; LI Ping; ZHENG Xiao-Liang; XIA Guang-Qing; HU Xi-Wei

    2011-01-01

    The electron energy distribution functions (EEDFs) are studied in the planar-type surface-wave plasma (SWP)caused by resonant excitation of surface plasmon polaritons (SPPs) using a single cylindrical probe.Sustained plasma characteristics can be considered as a bi-Maxwellian EEDF,which correspond to a superposition of the bulk low-temperature electron and the high-energy electron beam-like part.The beam component energy is pronounced at about 10eV but the bulk part is lower than 3.5eV.The hot electrons included in the proposed plasmas play a significant role in plasma heating and further affect the discharge chemistry.During the past several years,in the fabrication ofamorphous or crystalline silicon films,diamond film synthesis and carbon nanotube growth,the large-area overdense plasma source has been useful.In electronic device fabrication techniques such as etching,ashing or plasma chemical vapor deposition,overdense electrons and radicals are required,especially hot electrons.Among the various plasma devices,the planar-type surface-wave plasma (SWP) source is an advanced plasma source,which is a type of promising plasma source satisfying the above rigorous requirements for large-area plasma processing.%The electron energy distribution functions (EEDFs) are studied in the planar-type surface-wave plasma (SWP) caused by resonant excitation of surface plasmon polaritons (SPPs) using a single cylindrical probe. Sustained plasma characteristics can be considered as a bi-Maxwellian EEDF, which correspond to a superposition of the bulk low-temperature electron and the high-energy electron beam-like part. The beam component energy is pronounced at about 10 eV but the bulk part is lower than 3.5 eV. The hot electrons included in the proposed plasmas play a significant role in plasma heating and further affect the discharge chemistry.

  7. 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.

  8. Enhancement of wave growth for warm plasmas with a high-energy tail distribution

    Science.gov (United States)

    Thorne, Richard M.; Summers, Danny

    1991-01-01

    The classical linear theory of electromagnetic wave growth in a warm plasma is considered for waves propagating parallel to a uniform ambient magnetic field. Wave-growth rates are calculated for ion-driven right-hand mode waves for Kappa and Maxwellian particle distribution functions and for various values of the spectral index, the temperature anisotropy, and the ratio of plasma pressure to magnetic pressure appropriate to the solar wind. When the anisotropy is low the wave growth is limited to frequencies below the proton gyrofrequency and the growth rate increases dramatically as the spectral index is reduced. The growth rate for any Kappa distribution greatly exceeds that for a Maxwellian with the same bulk properties. For large thermal anisotropy the growth rate from either distribution is greatly enhanced. The growth rates from a Kappa distribution are generally larger than for a Maxwellian distribution, and significant wave growth occurs over a broader range of frequencies.

  9. Plasma production by helicon waves with single mode number in low magnetic fields

    CERN Document Server

    Sato, G; Hatakeyama, R; Sato, Genta; Oohara, Wataru; Hatakeyama, Rikizo

    2004-01-01

    Radio-frequency discharges are performed in low magnetic fields (0-10 mT) using three types of helicon-wave exciting antennas with the azimuthal mode number of $|m|$ = 1. The most pronounced peak of plasma density is generated in the case of phased helical antenna at only a few mT, where the helicon wave with $|m| = 1$ is purely excited and propagates. An analysis based on the dispersion relation well explains the density-peak phenomenon in terms of the correspondence between the antenna one-wavelength and the helicon wavelength. The $m=+1$ helicon wave propagates even in high magnetic fields where the density peaks are not observed, but the $m=-1$ helicon wave disappers. It is expected theoretically that the $m=-1$ helicon wave shows cutoff behavior in a low density region, [M. Kramer, Phys. Plasmas 6, 1052 (1999)], and the cutoff of $m=-1$ helicon wave experimentally observed coincides with the calculated one.

  10. DISPERSION RELATION OF A MAGNETIZED PLASMA-FILLED BACKWARD WAVE OSCILLATOR

    Institute of Scientific and Technical Information of China (English)

    GAO HONG; LIU SHENG-GANG

    2000-01-01

    A linear theory and a more general dispersion relation of electromagnetic radiation from a magnetized plasma-filled backward wave oscillator with sinusoidally corrugated slow-wave structure driven by a solid intense relativistic electron beam have been given. The comparisons show good agreement with the previous works when B0 → ∞ and ωb = 0 from this dispersion relation.

  11. Magneto-Acoustic Waves of Small Amplitude in Optically Thin Quasi-Isentropic Plasmas

    CERN Document Server

    Nakariakov, V M; Ibáñez, M H; Nakariakov, Valery M.; Mendoza-Briceno, Cesar A.

    1999-01-01

    The evolution of quasi-isentropic magnetohydrodynamic waves of small but finite amplitude in an optically thin plasma is analyzed. The plasma is assumed to be initially homogeneous, in thermal equilibrium and with a straight and homogeneous magnetic field frozen in. Depending on the particular form of the heating/cooling function, the plasma may act as a dissipative or active medium for magnetoacoustic waves, while Alfven waves are not directly affected. An evolutionary equation for fast and slow magnetoacoustic waves in the single wave limit, has been derived and solved, allowing us to analyse the wave modification by competition of weakly nonlinear and quasi-isentropic effects. It was shown that the sign of the quasi-isentropic term determines the scenario of the evolution, either dissipative or active. In the dissipative case, when the plasma is first order isentropically stable the magnetoacoustic waves are damped and the time for shock wave formation is delayed. However, in the active case when the plasm...

  12. Ionospheric electron acceleration by electromagnetic waves near regions of plasma resonances

    Science.gov (United States)

    Villalon, Elena

    1989-03-01

    Electron acceleration by electromagnetic fields propagating in the inhomogeneous ionospheric plasma is investigated. It is found that high-amplitude short wavelength electrostatic waves are generated by the incident electromagnetic fields that penetrate the radio window. These waves can very efficiently transfer their energy to the electrons if the incident frequency is near the second harmonic of the cyclotron frequency.

  13. Nonlinear Alfvén wave propagating in ideal MHD plasmas

    Science.gov (United States)

    Zheng, Jugao; Chen, Yinhua; Yu, Mingyang

    2016-01-01

    The behavior of nonlinear Alfvén waves propagating in ideal MHD plasmas is investigated numerically. It is found that in a one-dimensional weakly nonlinear system an Alfvén wave train can excite two longitudinal disturbances, namely an acoustic wave and a ponderomotively driven disturbance, which behave differently for β \\gt 1 and β \\lt 1, where β is the ratio of plasma-to-magnetic pressures. In a strongly nonlinear system, the Alfvén wave train is modulated and can steepen to form shocks, leading to significant dissipation due to appearance of current sheets at magnetic-pressure minima. For periodic boundary condition, we find that the Alfvén wave transfers its energy to the plasma and heats it during the shock formation. In two-dimensional systems, fast magneto-acoustic wave generation due to Alfvén wave phase mixing is considered. It is found that the process depends on the amplitude and frequency of the Alfvén waves, as well as their speed gradients and the pressure of the background plasma.

  14. Observation of Thomson Scattering off Entropy Waves in a Laser-Produced Plasma

    Institute of Scientific and Technical Information of China (English)

    ZHENG Jian; BAI Bo; LIU Wan-Dong; YU Chang-Xuan; JIANG Xiao-Hua; YUAN Xiao-Dong; LI Wen-Hong; ZHENG Zhi-Jian

    2001-01-01

    A new feature in the Thomson scattering spectrum is observed from a laser-produced aluminium plasma, which may be the Thomson scattering off entropy waves in the plasma. Such a feature is only observable when the energy of the heater beam is low enough.

  15. Dispersion relation for electromagnetic wave propagation in a strongly magnetized plasma

    CERN Document Server

    Marklund, G B M; Shukla, P K

    2006-01-01

    A dispersion relation for electromagnetic wave propagation in a strongly magnetized cold plasma is deduced, taking photon-photon scattering into account. It is shown that the combined plasma and quantum electrodynamic effect is important for understanding the mode-structures in magnetar and pulsar atmospheres. The implications of our results are discussed.

  16. A flowing plasma model to describe drift waves in a cylindrical helicon discharge

    CERN Document Server

    Chang, L; Cormac, C S

    2011-01-01

    A two-fluid model developed originally to describe wave oscillations in the vacuum arc centrifuge, a cylindrical, rapidly rotating, low temperature and confined plasma column, is applied to interpret plasma oscillations in a RF generated linear magnetised plasma (WOMBAT), with similar density and field strength. Compared to typical centrifuge plasmas, WOMBAT plasmas have slower normalised rotation frequency, lower temperature and lower axial velocity. Despite these differences, the two-fluid model provides a consistent description of the WOMBAT plasma configuration and yields qualitative agreement between measured and predicted wave oscillation frequencies with axial field strength. In addition, the radial profile of the density perturbation predicted by this model is consistent with the data. Parameter scans show that the dispersion curve is sensitive to the axial field strength and the electron temperature, and the dependence of oscillation frequency with electron temperature matches the experiment. These r...

  17. Modulational Instability of Dust Ion Acoustic Waves in a Collisional Dusty Plasma

    Institute of Scientific and Technical Information of China (English)

    XUEJu-Kui

    2003-01-01

    The modulational instability of dust ion accoustic waves in a dust plasma with ion-dust collision effects is studied.Using the perturbation method,a modified nonlinear Schroedinger equation contains a damping term that comes from the effect of the ion-dust collision is derived.It is found that the inclusion of the ion-dust collision would modify the modulational instability of the wave packet and could not admit any stationary envelope solitary waves.

  18. On the high frequency perpendicular propagating waves in ultra-relativistic fully degenerate electron plasma

    Science.gov (United States)

    Noureen, S.; Abbas, G.; Farooq, H.

    2017-09-01

    Using Vlasov-Maxwell's equations, the spectra of the perpendicular propagating Bernstein wave and Extraordinary wave in ultra-relativistic fully degenerate electron plasma are studied. The equilibrium particle distribution function is assumed to be isotropic Fermian. The analysis of high frequency spectra of the waves is carried out in the weak propagation limit Ω≫k .v and in the weak magnetic field limit |ω-k .v | ≫Ω and graphically observed.

  19. Observing the Plasma-Physical Processes of Pulsar Radio Emission with Arecibo

    Science.gov (United States)

    Rankin, Joanna M.

    2017-01-01

    With their enormous densities and fields, neutron stars entail some of the most exotic physics in the cosmos. Similarly, the physical mechanisms of pulsar radio emission are no less exotic, and we are only now beginning to understand them. The talk will provide an introduction to the phenomenology of radio pulsar emission and focus on those aspects of the exquisite Arecibo observations that bear on their challenging emission physics.The commonalities of the radio beamforms of most slow pulsars (and some millisecond pulsars) argue strongly that their magnetic fields have a nearly dipolar structure at the height of their radio emission regions. These heights can often be determined by aberration/retardation analyses. Similarly, measurement of the orientation of the polarized radio emission with respect to the emitting magnetic field facilitates identification of the physical(X/O) emission modes and study of the plasma coupling to the electromagnetic radiation.While the physics of primary plasma generation above the pulsar polar cap is only beginning to be understood, it is clear that the radio pulsars we see are able to generate copious amounts of electron-positron plasma in their emission regions. Within the nearly dipolar field structure of these emission regions, the plasma density is near to that of the Goldreich-Julian model, and so the physical conditions in these regions can be accurately estimated.These conditions show that the plasma frequencies in the emission regions are much higher than the frequency of the emitted radiation, such that the plasma couples most easily to the extraordinary mode as observed. Therefore, the only surviving emission mechanism is curvature radiation from charged solitons, produced by the two-stream instability. Such soliton emission has probably been observed directly in the Crab pulsar; however, a physical theory of charged soliton radiation does not yet exist.

  20. Emission of Gravitational Waves from a Magnetohydrodynamic Dynamo

    CERN Document Server

    Winterberg, Friedwardt

    2015-01-01

    The failure of the laser-interferometer gravitational wave antennas to measure the tiny changes of lengths many orders of magnitude smaller than the diameter of a proton raises the question of whether the reason for this failure is a large gravitational wave background noise, and if so, where this background noise is coming from. It is conjectured that it comes from gravitational waves emitted from a magnetohydrodynamic dynamo in the center of the sun, with the large magnetic field from this dynamo shielded by thermomagnetic currents in the tachocline. Using the moon as a large Weber bar, these gravitational waves could possibly be detected by the Poisson diffraction into the center of the lunar shadow during a total solar eclipse.