SKM 2021 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 4: Focus Session III: Diamond

KFM 4.4: Talk

Tuesday, September 28, 2021, 15:35–15:55, H2

Defect structures related to dielectric properties in diamond — •Theo Scherer, Gaetano Aiello, Sabine Schreck, Andreas Meier, and Dirk Strauß — KIT Karlsruhe (IAM-AWP)

State of the art windows used in high power electron cyclotron heating and current drive systems for large fusion devices such as ITER consist of a disk which is aligned perpendicular to the millimetre wave beam propagation. As reflection have to be kept on a minimal level, the window thickness restricts the allowed frequencies to a limited set defined by multiples of half wavelengths in the dielectric matter. Actual loss tangent values are several 1E-6 for the best polycrystalline materials. For frequency tunable systems in fusion reactors, corresponding to the gyrotron development, BREWSTER windows must be realized, where the elliptic cut diamond disk is inclined under the BREWSTER angle in the waveguide structure.