Development of coatings to improve RF voltage stand-off

For a reliable operation of Ion Cyclotron RF (ICRF) systems on fusion devices with magnetic confinement at high power, an improvement of the voltage stand-off of RF transmission lines and antennas is required. Coatings for RF conductors have been developed to increase the voltage stand-off. Stainless steel is often used as a basis material for the antenna components. The technique to reduce magnetic permeability of steel was elaborated. A technological process for deposition of TiN, TiC, W, Ta coatings with and without Cu sublayer was developed and tested. The coatings on the components of a RF probe were prepared for experiments with high RF voltage. The work function of the deposited coatings was measured. The application of the coating technology to the ICRF systems is discussed.