A hybridkinetic model for highβ plasmas
Abstract
A hybridkinetic model (Vlasov ions and driftkinetic electrons) is developed to describe the equilibrium and stability properties of collisionless highbeta plasmas in arbitrary magnetic field configurations. No ordering of ion properties (such as ω/Ω_{i} and r_{Li}/L_{⊥}) is assumed, so the ions are described by the exact (unexpanded) Vlasov equation. The electrons are assumed to be strongly magnetized with ω/Ω_{ɛ} ∼r_{Le}/L_{⊥}=ɛ≪1, and the electron Vlasov equation is expanded in ɛ to give a driftkinetic equation for f_{e}. Examples of linear screwpinch equilibria are constructed to demonstrate the ease with which equilibrium solutions are found within this formalism. Also, it is shown that the hybridkinetic model correct to O (ɛ) includes physical effects which are important during the implosion and immediate postimplosion phases of highdensity pinch experiments, where stability behavior is characterized by the fast time scale ω^{1}_{LH}= (Ω_{e}Ω_{i})^{1/2}. In particular, a local dispersion relation is derived for the modifiedtwostream and lowerhybriddrift instabilities, which have characteristic growth rates of order (Ω_{e}Ω_{i})^{1/2} when ω^{2}_{pe}/Ω^{2}_{e}≫1.
 Publication:

Physics of Fluids
 Pub Date:
 November 1975
 DOI:
 10.1063/1.861048
 Bibcode:
 1975PhFl...18.1507D
 Keywords:

 Collisionless Plasmas;
 Kinetic Equations;
 Magnetic Field Configurations;
 Magnetohydrodynamic Stability;
 Plasma Dynamics;
 Vlasov Equations;
 Distribution Functions;
 Drift Rate;
 Electromagnetic Fields;
 Mathematical Models;
 MaxwellBoltzmann Density Function;
 Plasma Frequencies;
 Plasma Pinch;
 Time Dependence;
 Plasma Physics