R.F. heating near the lower hybrid frequency in the FM-1 spherator

Technical Report · Mon Dec 01 04:00:00 EST 1975

DOI:https://doi.org/10.2172/4076788· OSTI ID:4076788

Hawryluk, R. J.; Davis, S. L.; Schmidt, J. A.

Plasma heating experiments at frequencies near the lower hybrid frequency have been carried out at modest powers (.05 to 4kW). The antenna structure operating at 68 MHz was comprised of two plates driven out of phase on the exterior of the plasma. High electron heating efficiency (greater than 40 percent) in both helium and argon plasmas was observed with only a weak density dependence. At low densities (n/sub e/ less than or equal to 1 x 10$sup 11$ cm$sup -3$), the heating was uniform across the plasma while at higher densities the heating was preferentially on the exterior portion of the plasma. The heating of the exterior of the plasma was found not to correspond to absorption at the lower hybrid resonance layer. The electron heating efficiency was found to be a weak function of rf power when the incident rf power was varied from 1 to 15 times the experimentally observed threshold power for parametric instabilities. Ion temperatures were determined by measuring the Doppler broadening of an Argon ion line using a Fabry-Perot interferometer. Low efficiency main body ion heating (1 to 3 percent) was observed. (auth)

• Research Organization: Princeton Univ., N.J. (USA). Plasma Physics Lab.
• NSA Number: NSA-33-022858
• OSTI ID: 4076788
• Report Number(s): MATT--1185
• Country of Publication: United States
• Language: English

Related Subjects

*FM DEVICES-- HIGH-FREQUENCY HEATING
*PLASMA HEATING-- HIGH- FREQUENCY HEATING
700101* --Fusion Energy--Plasma Research--Plasma Confinement & Heating
ARGON
HELIUM
HYBRID RESONANCE
N70100* --Physics--Controlled Thermonuclear Research-- Confinement & Heating