Regensburg 2019 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 8: Diamond I (joint session KFM/HL)

KFM 8.3: Talk

Tuesday, April 2, 2019, 10:10–10:30, PHY 5.0.20

Brewster-angle diamond window for microwave application — •Gaetano Aiello¹, Theo Scherer¹, Thomas Franke², John Jelonnek¹, Andreas Meier¹, Dirk Strauss¹, Quang Tran³, Christoph Wild⁴, and Eckhard Woerner⁴ — ¹KIT, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, Germany, 76344 — ²EUROfusion Consortium, Boltzmannstrasse 2, Garching, Germany, 85748 — ³Swiss Plasma Center (SPC), EPFL, Lausanne, Switzerland, 1015 — ⁴Diamond Materials GmbH, Hans-Bunte-Strasse 19, Freiburg, Germany, 79108

The Brewster-angle diamond window is a broadband window solution for the frequency step-tunable gyrotrons in the context of the DEMO EC H&CD system. It consists of an elliptical CVD diamond disk brazed to two copper WGs at the Brewster angle of 67.2° for diamond. This window concept is being investigated for long pulse gyrotron operation at 2 MW power. Main challenges along this path are the production of very large area optical grade diamond disks suited for a 63.5 mm WG aperture, the proper joining of the disks to the WGs and the design of an effective cooling layout. A 63.5 mm WG requires a minimum disk diameter of 180 mm and 2 mm thickness. Available state of the art microwave plasma reactors are not able of growing diamond disks of such size. In collaboration with Diamond Materials GmbH, tests aiming to obtain large disks were thus investigated by different methods and experiments are still ongoing. In this work, the results of these experiments shall be reported, also together with the results of the FEM analyses aiming to investigate different window cooling layouts.