High Power Heating in the Ion Cyclotron Range of Frequencies in the Wisconsin Tokapole II

A. P. Biddle and J. C. Sprott
Department of Physics, University of Wisconsin, Madison, WI 53706, U.S.A.
(Received 2 October 1980)


Fast wave heating at the second, third and fourth harmonics of the ion cyclotron resonance, and slow wave heating at the fundamental in a single ion species hydrogen plasma, are found to be in good agreement with warm plasma theory at rf power levels <= 130 kW. Ion heating is negligible off an eigenmode. Ion body temperatures are more than doubled to 75 eV from the 35 eV ohmically heated case with tails comprising 8% of the plasma at 320 eV. No deleterious effects except a non-disruptive 10% shortening of the discharge length caused by impurity influx are noted. A passive mode tracking technique allows ~ 40% increase in power deposition in a passing eigenmode over that of a fixed frequency rf source. Ion temperatures are limited by charge exchange due to the < 50 eV central temperature and the small 13 cm radius current channel.

Ref: A. P. Biddle and J. C. Sprott, Plasma Physics 23, 679-691 (1981)

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