Lower-hybrid turbulence in a nonuniform magnetoplasma

Journal Article · Sun Sep 01 00:00:00 EDT 1991 · Physics of Fluids B; (United States)

DOI:https://doi.org/10.1063/1.859969· OSTI ID:5362850

Stenzel, R L ^[1]

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1. Department of Physics, University of California, Los Angeles, California (USA)

An experimental study of a pressure-gradient-driven instability in a large discharge plasma (1 m diam, 2.5 m length, {ital n}{sub {ital e}}{congruent}10{sup 12} cm{sup 3}, {ital B}{congruent}14 G) is presented. When the electron diamagnetic drift {bold v}{sub {ital d}}={del}({ital nkT}{sub {ital e}}){times}{bold B}/{ital neB}{sup 2} exceeds the sound speed {ital c}{sub {ital s}}{congruent}({ital kT}{sub {ital e}}/{ital m}{sub {ital i}}){sup 1/2} ion-acoustic-like waves ({ital T}{sub {ital e}}{much gt}{ital T}{sub {ital i}}) are driven unstable. The growth rate maximizes near the lower-hybrid frequency {omega}{sub lh}{congruent}({omega}{sub {ital ce}}{omega}{sub {ital ci}}){sup 1/2} and the waves propagate essentially across {bold B} ({ital k}{sub {parallel}}{much lt}{ital k}{sub {perpendicular}}{congruent}{omega}{sub lh}/{ital c}{sub {ital s}}). The sound waves grow to large amplitudes ({delta}{ital n}/{ital n}{approx gt}50%) and saturate by wave steepening ({lambda}{sub D}{lt}{lambda}{sub {perpendicular}}{lt}{ital r}{sub {ital ce}}) and refraction ({del}{ital T}{sub {ital e}}{ne}0) away from the destabilizing drift {bold v}{sub {ital d}}. Magnetic fluctuations result from electron diamagnetic currents and opposing Hall currents associated with the wave density fluctuations. Ions are essentially unmagnetized ({nu}{sub {ital in}}/{omega}{sub {ital ci}}{gt}1) and slow compared to the magnetized electrons, {ital v}{sub {ital i}}/{ital v}{sub {ital d}}{congruent}({ital m}{sub {ital e}}/{ital m}{sub {ital i}}){sup 1/2}{much lt}1. In spite of the large amplitude waves little acceleration of electrons or ions is observed. The experiment employs a new technique of conditional averaging with digital oscilloscopes.

• OSTI ID: 5362850
• Journal Information: Physics of Fluids B; (United States), Vol. 3:9; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
PLASMA
TURBULENCE
ACCELERATION
LOWER HYBRID HEATING
MAGNETIZATION
PLASMA DIAGNOSTICS
PLASMA MICROINSTABILITIES
PRESSURE GRADIENTS
HEATING
HIGH-FREQUENCY HEATING
INSTABILITY
PLASMA HEATING
PLASMA INSTABILITY
700102* - Fusion Energy- Plasma Research- Diagnostics