Nonlinear finite beta saturation of the drift cyclotron loss cone instability

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:5020313

Ferraro, R D

The nonlinear saturation of a single Drift Cyclotron Loss Cone mode is considered in the case of a mirror confined finite {beta} plasma. The instability is modeled in slab geometry with the local approximation made. Using a variation of the Bogoliubov technique, analytic expressions are derived for the time asymptotic distribution function, electrostatic potential, and vector potential. The saturation amplitude and frequency shift are determined as functions of the fractional increase of the density above its threshold value. Freedom is retained in the equilibrium ion velocity space distribution function so that the effect of a partially filled loss cone may be investigated. A term neglected in a previous low {beta} application of this technique to the DCLC is found to affect the saturation results. In a collisionless, lossless model, the effect of a partially filled loss cone on the saturation amplitude and density, density gradient space stability boundary is demonstrated. A delta function equilibrium velocity space distribution is found to have only large amplitude saturated states. The nonlinear shift in the electrostatic potential is found to be negligibly small in this model, and the nonlinear shift in the vector potential is found to be just that needed to restore particle-field pressure balance. A second model is employed which takes into account plasma losses through a simple Krook type collision term in the Boltzman equation. Ion losses are assumed to be dominated by electron drag into the loss cone and the electron losses are modeled by the classical expression derived by Pastukhov.

• Research Organization: Rochester Univ., NY (USA)
• OSTI ID: 5020313
• Country of Publication: United States
• Language: English

Related Subjects

640301* -- Atomic
Molecular & Chemical Physics-- Beams & their Reactions
651000 -- Nuclear Physics
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCELERATORS
BOGOLYUBOV METHOD
CALCULATION METHODS
CYCLIC ACCELERATORS
CYCLOTRONS
GEOMETRY
INSTABILITY
LOSS CONE INSTABILITY
MATHEMATICAL MODELS
MATHEMATICS
MEDIUM-BETA PLASMA
PLASMA
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
SATURATION