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Ion temperature anisotropy instabilities in planetary magnetosheaths
Author(s) -
Remya B.,
Reddy R. V.,
Tsurutani B. T.,
Lakhina G. S.,
Echer E.
Publication year - 2013
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/jgra.50091
Subject(s) - instability , cyclotron , ion , physics , plasma , anisotropy , electron , atomic physics , proton , beta (programming language) , optics , nuclear physics , quantum mechanics , computer science , mechanics , programming language
There has been a lack of understanding why mirror modes are present in planetary magnetosheaths, at comets, and in the heliosheath. Linear theory indicates that the ion cyclotron instability should dominate over the mirror mode instability in electron‐proton plasma. In this paper, we take a new approach. We examine the role of plasma electron temperature anisotropy on the ion cyclotron and mirror mode instabilities. It will be shown that an inclusion of anisotropic electrons with T ⊥ e / T ∥ e ≥ 1.2 reduces the ion cyclotron growth rate substantially and increases the mirror mode growth rate. The minimum plasma beta for mirror instability dominance (over the ion cyclotron instability) is β p = 0.5.