A 2D simulation study of Langmuir, whistler, and cyclotron maser instabilities induced by an electron ring-beam distribution

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Title:	A 2D simulation study of Langmuir, whistler, and cyclotron maser instabilities induced by an electron ring-beam distribution
Authors:	Lee,KH;Omura,Y;Lee,LC
Contributors:	太空科學研究所
Keywords:	AURORAL KILOMETRIC RADIATION;SOLAR RADIO-BURSTS;DIRECT AMPLIFICATION;RELATIVISTIC DISPERSION;ELECTROMAGNETIC-WAVES;ENERGETIC ELECTRONS;EMISSION PROCESSES;KINETIC CYCLOTRON;DIRECT GENERATION;MAGNETIC FIELD
Date:	2011
Issue Date:	2012-03-27 17:31:19 (UTC+8)
Publisher:	國立中央大學
Abstract:	We carried out a series of 2D simulations to study the beam instability and cyclotron maser instability (CMI) with the initial condition that a population of tenuous energetic electrons with a ring-beam distribution is present in a magnetized background plasma. In this paper, weakly relativistic cases are discussed with the ring-beam kinetic energy ranging from 25 to 100 keV. The beam component leads to the two-stream or beam instability at an earlier stage, and the beam mode is coupled with Langmuir or whistler mode, leading to excitation of beam-Langmuir or beam-whistler waves. When the beam velocity is large with a strong beam instability, the initial ring-beam distribution is diffused in the parallel direction rapidly. The diffused distribution may still support CMI to amplify the X1 mode (the fundamental X mode). On the contrary, when the beam velocity is small and the beam instability is weak, CMI can amplify the Z1 (the fundamental Z mode) effectively while the O1 (the fundamental O mode) and X2 (the second harmonic X mode) modes are very weak and the X1 mode is not excited. In this report, different cases with various parameters are presented and discussed for a comprehensive understanding of ring-beam instabilities. (C) 2011 American Institute of Physics. [doi:10.1063/1.3626562]
Relation:	PHYSICS OF PLASMAS
Appears in Collections:	[Graduate Institute of Space Science] journal & Dissertation

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