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Electron Cyclotron Harmonic Wave Instability by Loss Cone Distribution
Author(s) -
Liu Xu,
Chen Lunjin,
Gu Wenyao,
Zhang XiaoJia
Publication year - 2018
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2018ja025925
Subject(s) - growth rate , electron , atomic physics , cyclotron , cyclotron resonance , instability , harmonic , physics , wavenumber , optics , computational physics , mathematics , geometry , mechanics , quantum mechanics
We propose a new method to construct a controllable and quantifiable loss cone distribution. Then, we derive a linear growth rate formula of the electrostatic mode for a realistic and arbitrary distribution function. Such formula is used to perform a parametric study of instability analysis of the electron cyclotron harmonic (ECH) wave in a plasma consisting of electron loss cone distribution and isotropic cold electron distribution. We find (1) the peak linear growth rate and the corresponding wave frequency increase with the loss cone size. The wave frequency of peak growth rate is about 1.5 and 2.5 times electron cyclotron frequency when loss cone is about 4–6° wide. The wave normal angle corresponding to the growth rate peak decreases with the loss cone size. (2) Increasing hot electron temperature anisotropy decreases the growth rate but hardly changes the wave frequency and wave normal angle corresponding to the growth rate peak. (3) Increasing hot electron parallel temperature tends to increase both the peak growth rate and wave normal angle but only change the corresponding wave frequency slightly. (4) The peak growth rate and its corresponding wave frequency increase with ω p e /|Ω e | for wavebands above or passing upper hybrid resonance frequency ω UHR and almost remain unchanged for wavebands below ω UHR . (5) Increasing cold electron temperature tends to decrease wave frequency and increase wave normal angle and peak growth rate for wavebands below ω UHR . The impact of our work on ECH wave generation and the significance of ECH waves on diffuse aurora are also discussed.