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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 12: Diamond and Related Dielectric Materials II

KFM 12.2: Talk

Wednesday, March 20, 2024, 09:50–10:10, TC 010

Application and design evolution of CVD diamond windows in fusion experiment devices — •Peter Spaeh — KIT, Institute for applied materials, Karlsruhe

For experimental fusion devices and also for future fusion power plants, efficient plasma heating concepts based on high frequency electromagnetic waves are essential. Electron Cyclotron Resonance Heating (ECRH) is one of these heating systems. An ECRH system generates very high power radiation at millimetre wavelength in Gyrotrons, which are basically evacuated masers. From there the millimetre waves are coupled out and guided through transmission lines into the torus chamber of the fusion reactor aiming for plasma heating or plasma stabilisation. To separate these sections from each other, radiation transparent windows are required, which enable millimetre wave passage at very low dielectrical losses, while at the same time acting as mechanical barriers to cope with pressure gradients and contamination issues. Beside window materials like sapphire, boron nitride or beryllium oxide, the most promising material for low-loss transmission and high mechanical strength under vacuum safe long pulse operation is synthetic diamond. With the continuous progress on growing diamond by CVD (chemical vapour deposition), also the applicability and the performance of CVD diamond windows in experimental fusion devices has evolved substantially. This talk gives an overview on various configurations and design evolutions of CVD diamond windows for nuclear fusion applications. Also respective design requirements, relevant design parameters and associated material properties are presented.

Keywords: CVD; Nuclear fusion; Diamond; ECRH; Window