Performance of internally sealed IRF antennas in CCT

The internally sealed ICRF antennas in CCT no longer show impurity problems in the steady state or in the pulsed mode. Experience over a 6 month period indicates a minimum of one order of magnitude reduction in impurity generation for comparable input power (50 kW) used in previous experiments. The antenna radiation resistances agree with computer calculation within experimental error. In the Fast Wave Current Drive regime cavity resonances are absent. The power transfer to the plasma is nearly ideal. It is now clear that the power goes to the ions at the edge, where confinement is poor. The absorption mechanism is not understood. Wave penetration to the center is only possible for extremely low (<1012cm3) densities.