Ion Cyclotron Resonance Heating in the Wisconsin Levitated Octupole
C. M. Fortgang, J. C. Sprott and E. J.
Strait
Department of Physics, University
of Wisconsin, Madison, Wisconsin 53706, U.S.A.
(Received 10 June 1983)
ABSTRACT
Ion cyclotron resonance heating has been investigated, both experimentally
and theoretically, on the Wisconsin Levitated Octupole. Heating of both
ions and electrons has been observed. Typically, a two component ion energy
distribution is produced (300 and 50 eV) with 500 kW of r.f. power coupled
into a 5 x 10^12 /cc plasma. Power is coupled to the plasma with an antenna
that also serves as the inductor of an oscillator tank circuit. The oscillator
is tunable from 1 to 3 MHz and can be applied for periods up to 10 ms.
The experiments were performed with hydrogen, gun-injected plasmas. Most
of the theoretical work presented deals with a calculation that predicts
the plasma loading. A slab model is used, and the questions of accessibility,
polarization and damping of the evanescent radio frequency electromagnetic
fields are addressed. It is found that cold plasma theory cannot account
for the heating, and therefore hot plasma theory is invoked to explain
the results. The loading measurements and theoretical predictions are found
to be in reasonable agreement.
Ref: C. M. Fortgang, J. C. Sprott and E. J.
Strait, Plasma Physics and Controlled Fusion 26, 589-602 (1984)
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