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Baldwin, D.E.; Berk, H.L.; Pearlstein, L.D.
Plasma physics and controlled nuclear fusion research 19741975
Plasma physics and controlled nuclear fusion research 19741975
AbstractAbstract
No abstract available
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International Atomic Energy Agency, Vienna (Austria); Proceedings series; 3 v.; v. 1 p. 301-310; ISBN 9200300758; ; 1975; IAEA; Vienna; 5. international conference on plasma physics and controlled nuclear fusion research; Tokyo, Japan; 11 Nov 1974; IAEA-CN--33/D1-1
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[en] We have studied the stability of magnetosonic wave in a plasma, where the ions and electrons are described by anti-loss cone (ALC) distributions. Our studies indicate that the magnetosonic waves produced by ions and electrons with ALC distributions are in the higher frequency end within the range of frequencies, as observed by the Combined Release and Radiation Effects Satellite spacecraft. They are weakly damped and can, therefore, travel long distances. These waves are expected to play an important role in the acceleration of radiation belt electrons. (author)
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Journal Article
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Indian Journal of Physics (Online); ISSN 0974-9845; ; v. 87(9); p. 939-945
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[en] Waves with frequencies near the harmonics of the proton-cyclotron frequency, and propagating almost transverse to the ambient magnetic field, can become unstable by hot protons having an anti-loss cone (ALC) distribution function. The maximum growth rates increase with an increase in anti-loss cone index, ratio of the temperatures of trapped to missing protons, and with a decrease in βHsub(H) (βsub(H) being the ratio of transverse thermal pressure of protons to magnetic field pressure). The growth rates are typically in the range 0.01-1.0 Ω, where Ω is the proton-cyclotron frequency. This instability may be relevant to the observations of EHC waves on auroral field lines (Kintner, 1979), ULF waves in the day-side magnetosphere (Perraut et al., 1978) and the low-frequency part of the electric field spectrum (from 5 Hz to 20 Hz) in the region upstream of the bow-shock (Gurnett et al., 1979). (orig.)
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Journal Article
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Astrophysics and Space Science; ISSN 0004-640X; ; v. 68(1); p. 175-182
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No abstract available
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Journal Article
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Plasma Physics; v. 17(5); p. 361-372
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[en] Observation of the adiabatic behaviour of energetic particle pitch-angle distributions in the magnetosphere (Lyons, 1977, and others) in the past indicated the development of pronounced minima or drift-loss cones on the pitch-angle distributions centred at α approx.= 900 in connection with storm-time changes in magnetospheric convection and magnetic field. Using a model of a drift-modified loss-cone distribution (MLCD) of the butterfly type, the linear stability of electromagnetic whistler or ion-cyclotron waves propagating parallel to the magnetic field has been investigated. The instability is shown to be quenched at high frequencies ω < ωsub(m) = A(A + 1), where A is the thermal anisotropy. This quenching becomes stronger the higher are the respective parallel hot particle thermal velocity Asub(h) and cold plasma density nsub(c). Particles around pitch-angles α approx. = 900 are identified as generating electromagnetic cyclotron waves near the marginally stable frequency ωsub(m). It is concluded that the absence of electromagnetic VLF and ELF noise during times when MLCD develops is the result of the shift of the unstable spectrum to low frequencies. (orig.)
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Journal Article
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Astrophysics and Space Science; ISSN 0004-640X; ; v. 72(1); p. 97-110
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[en] It is shown that in electron beam injected mirror plasmas, the convective loss cone instability gets modified substantially and so reduces the critical lenght by at least an order of magnitude. This will seriously jeopardize the open ended confinement schemes employing electron beams. (orig.)
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Journal Article
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Physics Letters. A; ISSN 0375-9601; ; v. 86(3); p. 155-160
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[en] Magnetospheric plasma just outside the plasmasphere is characterized by an antiloss cone (ALC) distribution function. A new high-frequency electrostatic instability in these ALC plasmas occurs if rho>rho/sub c/,rho being the strength of the antiloss cone. The growth rate for electrons (observed by Ogo 3) of energy density of approx.10-8 erg cm-3 can be approx.0.05Ω/sub e/, Ω/sub e/ being the local electron cycloton frequency. The characteristic frequencies associated with this instability correspond to time periods of approx.100--250 s; this may be a possible source for micropulsations of type Pc 5
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Journal Article
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Journal of Geophysical Research; v. 81(31); p. 5563-5566
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[en] The effects of adding warm plasmas on the kinetic DCLC mode in high β loss cone plasmas are investigated in detail. It is found that when the fluid DCLC mode is stabilized by a small amount of warm plasma, the kinetic excitation still remains due to two different mechanisms, namely, (1) magnetic drift resonance dissipation excites the negative energy wave; (2) a new type of positive energy wave can become unstable as the resonance condition is met. Comparing with fluid approximation theory, more warm plasmas are needed to suppress the kinetic DCLC instabilities
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Ziebell, L.F.
Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica1983
Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica1983
AbstractAbstract
[en] The amplified emission of electron cyclotron radiation near the fundamental frequency from an inhomogeneous, anisotropic plasma slab is investigated in a linear theory. Plasma polarization effects are consistently included. Expressions are developed in the WKB approximation for emission in the ordinary and the extraordinary modes, for propagation perpendicular to the magnetic field. Numerical results are given for the extraordinary mode, for which effects are strongest. For the case of a loss-cone-type electron momentum distribution, it is shown that the amplification is sensitively dependent on the ratio of parallel-to-perpendicular temperature and on inhomogeneities in the magnetic field. The dependence of the amplification on the distribution is further investigated by considering superpositions of loss-cone and Maxwellian components. It is show that the presence of a Maxwellian component in general reduces the emission relative to the pure loss-cone case, and situations occur in which a layer in the slab very effectively absorbs all the radiation amplified elsewhere. A peculiar behaviour of the refractive index, which occurs in the transition from the pure loss-cone to the pure Maxwellian case, is discussed. (author)
Original Title
Amplificacao de radiacao de ciclotron eletronica em plasmas termonucleares
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Source
1983; 115 p; Tese (Ph.D.).
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Miscellaneous
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Thesis/Dissertation
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[en] The cyclotron maser instability driven by a loss-cone distribution is reviewed in this report. The instability was firstly suggested by Wu and Lee, who attempted to explain the emission mechanism of the auroral kilometric radiation. The amplification of radiation is attributed to a relativistic cyclotron resonance between the wave and energetic electrons. In this paper, recent works and results are summarized and reported. (author). 5 refs, 6 figs
Primary Subject
Source
McNamara, B. (ed.) (Lawrence Livermore National Lab., CA (United States)); International Centre for Theoretical Physics, Trieste (Italy); 1234 p; ISBN 9971-966-37-9 V.1; ; ISBN 9971-966-38-7 V.2; ; 1984; p. 681-689; World Scientific; Singapore (Singapore); 1983 college on plasma physics; Trieste (Italy); Jun 1983
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Book
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Conference; Numerical Data
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