High power heating in the ion cyclotron range of frequencies in the Wisconsin Tokapole II

Abstract

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 gQod agreement with warm plasma theory at rf power levels 5130 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 nondisruptive 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 <50eV central temperature and the small 13 cm radius current channel.

Ion heating in the range of high ion cyclotron harmonics on EBT

“…The principal point made in the paper is that ion heating has been obtained in EBT experiments in the range of high ion cyclotron harmonics (OJ/£2J k 3). A similar phenomenon has been reported in only a few recent experiments [10][11][12][13]. It has also been shown in this paper that high-harmonic heating can occur in the plasma centre.…”

“…While the subject has not received widespread attention, ion heating at frequencies above the second harmonic of the ion-cyclotron frequency has been reported in a number of experiments [10][11][12][13]. Most recently, Ref.…”

Perpendicular Ferromagnetic-Resonance Equations Derived by Effective Demagnetizing Factors

“…The fraction of RF power absorbed directly by ions cannot be determined accurately from the available data obtained along a single sightline; however, for an explanation of the results a much higher mode conversion efficiency than what is predicted by a simple theory [18] may be required. Heating at high ion cyclotron harmonics was observed previously in fast wave experiments on other toroidal devices [20,21].…”

The behaviour of fast ions in tokamak experiments

“…On JT-60, beam ion acceleration during combined hydrogen beam injection and third harmonic ICRF heating was observed with perpendicular active charge-exchange diagnostics [136,143,1441. Second, third and fourth harmonic acceleration of hydrogen were observed on TOKAPOLE I1 [145]. Fourth harmonic deuterium beam acceleration was observed on JET [146].…”