Regensburg 2025 – scientific programme
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 15: Crystal Structure Defects / Real Structure / Microstructure
KFM 15.2: Talk
Thursday, March 20, 2025, 10:00–10:15, H9
Numerical analyses and loss tangent measurements for the W7-X ECRH gyrotron diamond output windows — •Gaetano Aiello1, Andreas Meier1, Heinrich Peter Laqua2, Theo Scherer1, Sabine Schreck1, and Dirk Strauss1 — 1KIT, Karlsruhe, Germany — 2IPP, Greifswald, Germany
The 140 GHz 1 MW gyrotron for the electron cyclotron resonance heating (ECRH) system at the stellarator Wendelstein 7-X (W7-X) is being upgraded to 1.5 MW continuous wave operation to increase the total heating power for achieving operating regimes with high plasma beta and low collisionality. The gyrotron features a chemical vapor deposition (CVD) polycrystalline diamond window with an aperture of 88 mm and a disk of 1.8 mm thickness and 106 mm diameter. In this work, numerical analyses of the window are shown with loss tangent values provided by experimental measurements on 25 bare diamond disks. Computational fluid dynamics (CFD) conjugated heat transfer and structural analyses were carried out to check the window performance at 1.5 MW operation, when cooled by water and silicon oil Dow Corning 200(R) 5cSt.
Keywords: Diamond; Window; FEM analyses; CFD analyses; Loss tangent