1.5 MW, 140 GHz Gyrotron for W7-X - development status and experimental results -

For the upgrade of the Electron Cyclotron Resonance Heating (ECRH) system of the stellarator Wendelstein 7-X (W7- X), a 1.5 MW, 140 GHz continuous-wave (CW) gyrotron is under development. In order to provide a first experimental verification of the scientific microwave and electron beam optics design of the gyrotron at pulse lengths of a few milliseconds (ms), Karlsruhe Intitule of Technology (KIT) has developed and tested successfully a short-pulse pre-prototype gyrotron. The tube was stably operated at up to 1.6 MW output power. The status of the project as well as the results achieved during the first experimental campaign, are presented in this paper.