FAST ION STUDIES OF ION CYCLOTRON HEATING IN THE PLT TOKAMAK (FUSION, QUASILINEAR, CHARGE-EXCHANGE, POWER DENSITY, TRANSPORT

The most promising method for heating a tokamak reactor plasma to thermonuclear temperatures is the use of waves in the ion cyclotron range of frequencies. Measurements of the fast non-Maxwellian ions which are produced by this heating method provide a wealth of information about the physics of wave heating. Previous experiments have demonstrated that ion cyclotron heating tends to produce energetic ions whose banana tips are near the resonance layer. Cyclotron heating causes this "resonance localization" by imparting perpendicular energy to particles, and by imparting more energy to particles which spend more time in the resonance layer. A bounce-averaged quasilinear operator which properly includes these effects has been implemented in a Fokker-Planck code in order to make detailed comparisons with measurements. Good agreement is found with data from a horizontally-scanning, mass-resolving, neutral particle analyzer, although the assumed RF power deposition profile needed to match the data is broader than expected in some cases. Alternatively, radial diffusion of fast ions (which is ignored in the code) may make the RF power profile appear to be broader than it is. In addition to the usual charge exchange measurements of hydrogen and deuterium, double charge exchange measurements of ('3)He have been made. Direct second harmonic heating of deutrium or tritium is a preferred technique for a reactor. The transition from hydrogen fundamental heating to deuterium second harmonic heating at low hydrogen concentrations has been clearly demonstrated. As isotropic model fit to the deuterium tail provides a direct measure of the central deuterium power density. These measurements are consistent with sawtooth broadening of the RF power profile and indicate that as much as 20% of the central RF power is directly absorbed by the deuterium in these experiments.