Absolute maximum growth rates and enhancement of unstable electromagnetic ion-cyclotron waves in mixed warm-cold plasmas

S. Cuperman, L. Gomberoff, A. Sternlieb

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Abstract

The paper presents analytic and numerical calculations of the absolute maximum growth rates and enhancement of the electromagnetic ion-cyclotron instability in mixed warm-cold plasmas. For a plasma system consisting of warm and anisotropic protons (βp = 8πnp, w KTII, P|B2 0≠0, Ap≡T ⊥, P|TII, p—1≠ 0) and cold protons, the following hold: (i) The growth rate of any mode x ≡ωrp is maximized for a relative cold plasma concentration np, c /np, w= [(1-x)3/1.5βpχ2]-1. (ii) The absolute maximum growth rate occurs for an optimum np, c /np, w value about [16/3βp(A:p+ 2)]—1. (iii) A significant enhancement occurs only if PppA 2p(Ap+ 1) < 1. The enhancement decreases exponentially with increasing Ppvalues, (iv) But, in all cases with np, c /np, w0, the instability range in k space is increased by a factor of about (1 +np, c /np, w ½. The paper also presents simple analytical (approximate) expressions for maximum growth rates and enhancement, as well as for the optimum relative cold plasma concentrations.

Original languageEnglish
Pages (from-to)259-272
Number of pages14
JournalJournal of Plasma Physics
Volume13
Issue number2
DOIs
StatePublished - Apr 1975

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