Particle and wave dynamics in a magnetized plasma subject to high rf pressure

Journal Article · Mon Aug 01 04:00:00 EDT 1977 · Phys. Fluids; (United States)

DOI:https://doi.org/10.1063/1.862014· OSTI ID:7299985

Gekelman, W; Stenzel, R L

The nonlinear response of a plasma subject to an intense, spatially localized rf field has been investigated experimentally. In a uniform quiescent magnetoplasma of density n/sub e/approximately-greater-than10/sup 9/ cm/sup -3/, temperature kT/sub e/approx. =5 kT/sub i/approx. =1 eV, and magnetic field B/sub 0/approx.100 G, a resonance cone (..omega../..omega../sub c/approx. =0.1; where ..omega../sub c/ is the electron cyclotron frequency) is established which converges away from a circular exciter to reach a maximum amplitude at the remote cone apex. When an rf burst of intensity epsilon/sub 0/E/sub rf//sup 2//n/sub e/kT/sub e/approximately-less-thanO (1) is applied, a strong density depression (deltan/sub e//n/sub e/approx. =40%) is formed in the focal region on a time scale (approx.1 ..mu..sec) short compared with a collision time. Fast ion bursts ((1/2) mv/sub i//sup 2/approx. =35 eVapproximately-greater-than100 kT/sub i/), large amplitude ion acoustic waves, but negligible electron temperature increases are observed. Density and resonance cone field interact nonlinearly and in time develop a state of turbulence. Ion heating (..delta..T/sub i//T/sub i/approx. =100) dominates over electron heating (..delta..T/sub e//T/sub e/approx.2). The direct measurements of the particle distributions with probes and energy analyzers are supplemented by test wave techniques. Small amplitude ion acoustic, electron plasma, and Bernstein waves are propagated through the region of high rf intensity and the perturbed plasma properties are deduced from the test wave behavior. The observed nonlinear collisionless interactions between particles and intense rf field are qualitatively explained by a model involving the ponderomotive force on electrons and acceleration of ions by space charge fields.

• Research Organization: Department of Physics, University of California, Los Angeles, California 90024
• OSTI ID: 7299985
• Journal Information: Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 20:8; ISSN PFLDA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
700108 -- Fusion Energy-- Plasma Research-- Wave Phenomena
DISTURBANCES
ELECTRIC PROBES
HEATING
HIGH-FREQUENCY HEATING
ION WAVES
MAGNETIC FIELDS
NONLINEAR PROBLEMS
PLASMA DENSITY
PLASMA HEATING
PLASMA WAVES
PROBES
WAVE PROPAGATION