Development of High Power RF Transmission Components for Long Pulse Operation

The high power RF transmission components are developed for transmitting MW level of RF power continuously in ICRF heating and current drive system. A water-cooled co-axial transmission line with the special connector for water sealing while maintaining electrical contact, a vacuum feedthrough of 1 MW RF power which. has two alumina (Al₂O₃, 97%) ceramic cylinders and O-ring seal instead of a brazed seal for good mechanical and thermal strength, and the phase shifter using liquid instead of gas for insulating dielectric medium were developed. RF tests show that stable operation is possible with the peak voltage over 30 kV for 300 seconds.