Status of the 140 GHz, 10 MW CW transmission system for ECRH on the stellarator W7-X

• Published in: Fusion engineering and design 2005-11, Vol.74 (1), p.243-248
• Main Authors: Kasparek, W., Brand, P., Braune, H., Dammertz, G., Erckmann, V., Gantenbein, G., Hollmann, F., Grünert, M., Kumric, H., Jonitz, L., Laqua, H.P., Leonhardt, W., Michel, G., Noke, F., Plaum, B., Purps, F., Schmid, M., Schulz, T., Schwörer, K., Thumm, M., Weissgerber, M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Controled nuclear fusion plants; Electron cyclotron heating; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Installations for energy generation and conversion: thermal and electrical energy; Microwave reflectors; Multi-beam transmission; Remote-steering
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2005.06.247

The stellarator W7-X, which is currently under construction at IPP Greifswald, Germany, will be equipped with a 10 MW ECRH system working at 140 GHz in CW regime. The microwave power will be generated by 10 gyrotrons delivering 1 MW each and will be transmitted from the gyrotron hall to the W7-X stellarator ports via a fully optical system. The status of the construction of the transmission lines and the design of the launchers is reported. Low-power tests of a prototype system at IPF Stuttgart are reviewed. Now, the first two gyrotrons are operating at IPP Greifswald, and high-power long-pulse tests have started. Measurements on transmission performance, behaviour of the water-cooled mirrors under thermal and microwave loads as well as alignment issues, characteristics of directional couplers, calorimetric loads, and other diagnostics are discussed.