Investigations of dielectric RF properties of ultra low loss CVD diamond disks for fusion applications

To determine the high-power long pulse RF loss properties of CVD diamond window disks for the ITER ECRH Upper Launcher a Fabry-Perot measurement setup has been used. The dielectric loss is strongly influenced by the surface chemistry of the diamond. Special surface engineering techniques are available due to the reduction of the electrical surface conductivity and therefore of the RF losses.