Gyrokinetic theory of the screw pinch

Journal Article · Thu Jun 01 04:00:00 EDT 1989 · Phys Fluids B; (United States)

DOI:https://doi.org/10.1063/1.858997· OSTI ID:6265984

Stefant, R J

The gyrokinetic differential equation for waves propagating in a hot collisionless current-carrying plasma is derived in cylindrical geometry. It is shown that the averaging of the wave electric field over the ion Larmor circle leads to a transcendental differential equation (d.e.) of infinite order in the radial derivative. This reduces to a d.e. of sixth order when the scale length of the plasma inhomogeneity L/sub n/ is greater than the ion gyroradius rho/sub i/ by a factor (M/m)/sup 1//sup ///sup 2/, where M and m are, respectively, the ion and electron mass. This sixth-order d.e. describes the properties of the two (compressional and torsional) Alfven modes and the ion acoustic mode. When L/sub n/ <(M/m)/sup 1//sup ///sup 2/rho/sub i/, the plasma can only support modes of the magnetokinetic (short wavelength) type. In the absence of a finite Larmor radius (FLR) effect, shear, and equilibrium current, we find that the correct equation to start with is the Hain and Lust (Z. Naturforsch. A 13, 936 (1958)) d.e. of second order that is singular at the Alfven resonance layer (ARL). The ARL behaves in that case like a Budden absorption layer that traps the global Alfven eigenmodes (GAEM) inside the plasma cavity where they are damped by transit time magnetic pumping (TTMP). The logarithmic singularity does not disappear with the introduction of the FLR effect in the Hain and Lust d.e., but only with the TTMP damping term. There is no mode conversion between the fast magnetosonic mode and the shear or magnetokinetic mode at the ARL or anywhere in the plasma. In the presence of shear and equilibrium current, the correct equation to use is a d.e.

• Research Organization: 101 First Street, Suite 193, Los Altos, California 94022
• OSTI ID: 6265984
• Journal Information: Phys Fluids B; (United States), Journal Name: Phys Fluids B; (United States) Vol. 1:6; ISSN PFBPE
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107 -- Fusion Energy-- Plasma Research-- Instabilities
700108* -- Fusion Energy-- Plasma Research-- Wave Phenomena
COLLISIONLESS PLASMA
CURRENTS
CYLINDERS
DIFFERENTIAL EQUATIONS
ELECTRIC CURRENTS
ELECTRIC FIELDS
EQUATIONS
EQUILIBRIUM
HOT PLASMA
LARMOR RADIUS
LINEAR PINCH DEVICES
LINEAR SCREW PINCH DEVICES
OPEN PLASMA DEVICES
PINCH DEVICES
PLASMA
THERMONUCLEAR DEVICES
WAVE PROPAGATION