Design of High Power Vacuum Feedthrough for Multipactor Effect Suppression

A helicon current drive system need the high power vacuum feed-through (VFT) for the of upgraded KSTAR helicon current drive system. However, multipactor effect shows a problem of RF reflection in VFT vacuum region. So the proposed structure was to place a low electric field in the ceramic using a standing wave. The designed VFT shows the $\mathrm{E}_{\mathrm{z}}$ value close to zero and the electric field absolute value of about 1.7kV/cm when transmitting 1MW in ceramic. It showed the high Q value of transmission characteristics at 476MHz.