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

G. Gantenbein¹, G. Dammertz¹, V. Erckmann², S. Illy¹, W. Kasparek³, C. Lechte³, C. Liévin⁴, B. Piosczyk¹, M. Schmid¹, M. Thumm^{1, 5}

¹Forschungszentrum Karlsruhe, Association EURATOM-FZK, Institut für Hochleistungsimpuls- und Mikrowellentechnik, Hermann-von-Helmholtz-Platz 1
D-76344 Eggenstein-Leopoldshafen, Germany

²Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, Association EURATOM,

Wendelsteinstr. 1, D-17491 Greifswald, Germany

³Institut für Plasmaforschung, Universität Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart, Germany

⁴Thales Electron Devices, 2 Rue de Latécoère, F-78141 Vélizy-Villacoublay, France

⁵Universität Karlsruhe, Institut für Höchstfrequenztechnik und Elektronik,

Kaiserstr. 12, D-76131 Karlsruhe, Germany

For the stellarator W7-X which is presently under construction at the Max-Planck-Institute for Plasma Physics (IPP) in Greifswald an Electron Cyclotron Resonance Heating (ECRH) system with a total power of 10 MW at 140 GHz and 30 min operation is currently being built up. In a collaboration with European research laboratories and European tube industry (Thales Electron Devices (TED) in France), cylindrical cavity gyrotrons designed for an output power of 1 MW, CW at 140 GHz have been developed.

After the series gyrotrons No. 2 and 3 have failed to fulfil the specified power and pulse length, these tubes were shipped back to TED for inspection. The next series tube (SN4) was assembled with improved quality control and was sent to FZK. This tube was under experimental investigation at FZK and passed the factory acceptance tests. In this contribution we will present high-power experiments with the series gyrotron No.4.