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Title: Parametric up-conversion of an electron Bernstein mode by a relativistic electron beam in a plasma

Abstract

A relativistic electron beam, propagating with velocity v{sub 0b} parallel z in a magnetized plasma, parametrically up-converts a pre-existing electron Bernstein wave ({omega}{sub 0},k{sub 0}) into electromagnetic radiation when k{sub 0}{center_dot}v{sub 0b}<0. The Bernstein wave couples with a negative energy space-charge mode ({omega},k) to produce a frequency up-converted sideband electromagnetic wave. The sideband and the Bernstein wave exert a ponderomotive force, driving space-charge mode. In the Compton regime, the growth rate of the parametric instability scales as two-third power of the pump amplitude, whereas in the Raman regime, it goes linearly.

Authors:
;  [1]
  1. Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110016 (India)
Publication Date:
OSTI Identifier:
20974980
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 5; Other Information: DOI: 10.1063/1.2736368; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AMPLITUDES; BEAM-PLASMA SYSTEMS; BERNSTEIN MODE; ELECTROMAGNETIC RADIATION; ELECTRON BEAMS; ELECTRONS; NONLINEAR PROBLEMS; PARAMETRIC INSTABILITIES; PLASMA; PLASMA WAVES; PONDEROMOTIVE FORCE; RELATIVISTIC RANGE; SPACE CHARGE

Citation Formats

Kumar, Asheel, and Tripathi, V. K. Parametric up-conversion of an electron Bernstein mode by a relativistic electron beam in a plasma. United States: N. p., 2007. Web. doi:10.1063/1.2736368.
Kumar, Asheel, & Tripathi, V. K. Parametric up-conversion of an electron Bernstein mode by a relativistic electron beam in a plasma. United States. doi:10.1063/1.2736368.
Kumar, Asheel, and Tripathi, V. K. Tue . "Parametric up-conversion of an electron Bernstein mode by a relativistic electron beam in a plasma". United States. doi:10.1063/1.2736368.
@article{osti_20974980,
title = {Parametric up-conversion of an electron Bernstein mode by a relativistic electron beam in a plasma},
author = {Kumar, Asheel and Tripathi, V. K.},
abstractNote = {A relativistic electron beam, propagating with velocity v{sub 0b} parallel z in a magnetized plasma, parametrically up-converts a pre-existing electron Bernstein wave ({omega}{sub 0},k{sub 0}) into electromagnetic radiation when k{sub 0}{center_dot}v{sub 0b}<0. The Bernstein wave couples with a negative energy space-charge mode ({omega},k) to produce a frequency up-converted sideband electromagnetic wave. The sideband and the Bernstein wave exert a ponderomotive force, driving space-charge mode. In the Compton regime, the growth rate of the parametric instability scales as two-third power of the pump amplitude, whereas in the Raman regime, it goes linearly.},
doi = {10.1063/1.2736368},
journal = {Physics of Plasmas},
number = 5,
volume = 14,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • A gyrating relativistic electron beam supports negative energy modes near the harmonics of the electron cyclotron frequency. An electromagnetic wave passing through such a beam parametrically up-converts into high frequency electromagnetic radiation, producing a beam cyclotron mode. In the case when pump frequency {omega}{sub 0} is away from the harmonics of cyclotron frequency, {omega}{ne}{ital l}{omega}{sub {ital c}}/{gamma}{sub 0} and {omega}{gt}{omega}{sub {ital c}}/{gamma}{sub 0}, the beam response to the pump and sideband waves is obtained by the fluid theory whereas the response at the beam cyclotron mode is kinetic. In the case when {omega}{sub 0}{approximately}{ital l}{omega}{sub {ital c}}/{gamma}{sub 0} the beammore » response to all three interacting waves is taken to be fully kinetic. It is seen that the normalized growth rate decreases as {omega}{sub 0}{minus}{omega}{sub {ital c}}/{gamma}{sub 0} increases for Raman as well as Compton regimes of operation. {copyright} {ital 1996 American Institute of Physics.}« less
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  • Parametric coupling between negative energy beam synchronous modes and positive energy plasma oscillation modes of a uniform beam-plasma system, due to the presence of sinusoidal density modulation in the monoenergetic, relativistic electron beam, have been theoretically investigated on the basis of linearized Vlasov--Poisson equations using a multiple-time-scale perturbation theoretical approach. It has been found that, for a given beam-to-plasma density ratio, there exists an upper limit to the initial beam energy for which the instabilities can be excited. Within the allowed range, maximum linear growth rate exhibits a minimum as the beam energy increases from its nonrelativistic value. To determinemore » the effectiveness of the parametric interaction process, feedback effects of the instabilities on the beam-plasma distribution functions have also been considered and estimates of energy transfers have been made. For typical parameters, the beam is found to lose about 15% of its initial kinetic energy during the ''hydrodynamic'' stage and the time required is about 4.72 nsec. (AIP)« less