Microwave testing of a CVD diamond torus window prototype for iter

Abstract

For the plasma engineering of ITER, EC launchers will be used at the mid and top port levels. The EU is preparing the procurement of the upper port plug and JA the procurement of the equatorial. Part of these studies is to verify the window design and to work out, whether a concept is available for both launchers. To this goal, first experiments with low and high power mm-waves are performed and will be presented. The high power RE behavior of torus window assemblies with corrugated waveguides is being investigated by using IR imaging technique during high power microwave loading up to 1 MW at a frequency of 170 GHz at the JAEA gyrotron facility. Short and long pulse experiments are being performed to determine the temperature distribution over the whole diamond window area and the efficiency of the indirect cooling by a copper cuff. The occurrence of arcing is being studied as part of evaluation of the assembly design. For a characterization of the dielectric losses a low power measurement in a Fabry-Perot resonator setup at 170 GHz of the bare as-grown diamond disk will be compared with the brazed disk in the window housing. The evaluation of the curvature of the diamond disk is used as indicator of the residual stresses introduced in the joining process.