Wave generation and heating near ion cyclotron frequency in the ST Tokamak

The results of the recent, high power ICRH experiments performed on the ST Tokamak are reported. It was demonstrated that both the fast and slow waves could be generated in toroidal geometry, and heating of the plasma ions at power levels up to 1 MW was observed both at the ion cyclotron frequency (ω/sub ci/) and its second harmonic (2ω/sub ci/). Measurements by a charge exchange neutral detector directed tangentially to the plasma torus revealed that at 2ω/sub ci/ the ion energy within the bulk of the ion distribution function (''parallel body temperature'') could be increased from about 100 eV up to 200 eV with efficiencies ranging from 8 to 45 percent. Efficiency at ω/sub ci/ in raising the parallel temperature was less than at 2ω/sub ci/. Charge exchange neutral detection perpendicular to the plasma column showed that both at ω/sub ci/ and 2ω/sub ci/ the ''perpendicular body temperature'' was enhanced very rapidly by a factor of up to 3. Also, buildup of a high energy ''tail'' in the ion energy distribution was observed. Power transfer to the ions seemed extremely efficient. (auth)