Regensburg 2019 – wissenschaftliches Programm
KFM 14.9: Poster
Mittwoch, 3. April 2019, 16:00–18:30, Poster C
Loss tangent mapping measurement on large area diamond discs - An approved quality control method — •Andreas Meier and Theo Scherer — Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
As part of electron cyclotron development for heating of several fusion experiments (W7X, Asdex Upgrade, ITER) the characterization on bare and brazed polycrystalline chemical vapour deposition (CVD) diamond discs has been performed. An overview of dielectric properties particularly the loss tangent on about 70 different large area torus and gyrotron windows (Ø80mm - 140mm) realised with low power open resonators is shown. A spherical resonator is used for high-resolution measurements (loss tangent 10E-6) at the centre of the disc. Quality control measuring relating to the homogeneity has been realised with a hemispherical mapping setup (spherical and plane mirror). The results are given in statistic value D10 (10% of analysed area) D50 and D90. An additional optical characterisation method is intended for polished ITER torus discs to identify non-diamond like phase inclusions and cracks. The detection of these defect structures with a microscope is performed by an automatical scale-up mapping in all spatial directions. Size and location of defects are the basis for the quality assurance.