Abstract: | In the present paper magnetohydrodynamic models are employed to investigate the stability of an inhomogeneous magnetic plasma with respect to perturbations in which the electric field may be regarded as a potential field (rot E 0). A hydrodynamic model, actually an extension of the well-known Chew-Goldberg er-Low model 1], is used to investigate motions transverse to a strong magnetic field in a collisionless plasma. The total viscous stress tensor is given; this includes, together with magnetic viscosity, the so-called inertial viscosity.Ordinary two-fluid hydrodynamics is used in the case of strong collisions=. It is shown that the collisional viscosity leads to flute-type instability in the case when, collisions being neglected, the flute mode is stabilized by a finite Larmor radius. A treatment is also given of the case when epithermal high-frequency oscillations (not leading immediately to anomalous diffusion) cause instability in the low-frequency (drift) oscillations in a manner similar to the collisional electron viscosity, leading to anomalous diffusion.Notation
f
particle distribution function
- E
electric field component
- H0
magnetic field
-
density
- V
particle velocity
- e
charge
- m, M
electron and ion mass
- i, e
ion and electron cyclotron frequencies
-
viscous stress tensor
- P
pressure
- ri
Larmor radius
- P
pressure tensor
- t
time
-
frequency
- T
temperature
-
collision frequency
-
collision time
- j
current density
- i, e
ion and electron drift frequencies
- kx, ky, kz
wave-vector components
- n0
particle density
- g
acceleration due to gravity.
The authors are grateful to A. A. Galeev for valuable discussion. |