LINEAR THEORY OF WEAKLY AMPLIFIED, PARALLEL PROPAGATING, TRANSVERSE TEMPERATURE-ANISOTROPY INSTABILITIES IN MAGNETIZED THERMAL PLASMAS

Journal Article · Sun Jun 20 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/716/2/1596· OSTI ID:21457128

Schlickeiser, R; Skoda, T ^[1]

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1. Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

A rigorous analytical study of the dispersion relations of weakly amplified transverse fluctuations with wavevectors ( k-vector {parallel} B-vector ) parallel to the uniform background magnetic field B-vector in an anisotropic bi-Maxwellian magnetized electron-proton plasma is presented. A general analytical instability condition is derived that holds for different values of the electron (A{sub e}) and proton (A{sub p}) temperature anisotropies. We determine the conditions for which the weakly amplified left-handed (LH) polarized Alfven proton cyclotron and right-handed (RH) polarized Alfven Whistler electron cyclotron branches can be excited. For different regimes of the electron plasma frequency phase speed w = {omega}{sub p,e}/(kc) these branches reduce to the RH- and LH-polarized Alfven waves, RH-polarized high and low phase speed Whistler, RH-polarized proton, and LH-polarized electron cyclotron modes. Analytic instability threshold conditions are derived in terms of the combined temperature anisotropy A = T{sub perpendicular}/T{sub {parallel}}, the parallel plasma beta {beta}{sub {parallel}} = 8 {pi} n{sub e}k{sub B}T{sub {parallel}}/B {sup 2} and the electron plasma frequency phase speed w = {omega}{sub p,e}/(kc) for each mode. The results of our instability study are applied to the observed solar wind magnetic turbulence at values of 90 {<=} w {<=} 330. According to the existence conditions of the different instabilities, only the LH- and RH-polarized Alfven wave instabilities can operate here. Besides the electron-proton mass ratio {mu} = 1836, the Alfvenic instability threshold conditions are controlled by the single observed plasma parameter w. The Alfvenic instability diagram explains well the observed confinement limits at small parallel plasma beta values in the solar wind.

• OSTI ID: 21457128
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 716; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
79 ASTRONOMY AND ASTROPHYSICS
ALFVEN WAVES
ANISOTROPY
BARYONS
DISPERSION RELATIONS
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HYDROMAGNETIC WAVES
LANGMUIR FREQUENCY
LEPTONS
MAGNETIC FIELDS
NOISE
NUCLEONS
PLASMA
PROTONS
RADIATIONS
RADIO NOISE
RADIOWAVE RADIATION
SOLAR ACTIVITY
SOLAR WIND
STELLAR ACTIVITY
STELLAR WINDS
TURBULENCE
VELOCITY
WHISTLERS