RF high voltage performance of RF transmission line components on the DIII-D Fast Wave Current Drive (FWCD) System

The performance of the high voltage RF components of the DIII-D Fast Wave Current Drive System (FWCD) have been evaluated under various conditions of insulator configuration, insulator material, insulating gas and gas pressure. The insulator materials that have been investigated are alumina, steatite, pyrex, quartz, and teflon. The results of this evaluation are discussed in this paper. Additionally an RF high potter was developed to aid in the evaluation of RF high voltage components. The high potter consists of a 50 /spl Omega/, 1/4 wavelength cavity with a variable position short and a 50 ohm matched tap at one end of the cavity. With this configuration RF voltages were generated in excess of 100 kVp in the frequency range 30 to 60 MHz.