Electron Cyclotron Resonance Heating for W7-X

The HELIAS‐type Stellarator Wendelstein 7‐X, which is currently under construction in Greifswald, Germany, will be equipped with a 140 GHz, 10 MW, CW ECRH system. It will be the main plasma heating system for W7‐X. The key features and capabilities of the ECRH plant will be discussed together with the envisaged start‐up and heating scenarios. We also report on the ECRH stray radiation test facility MISTRAL and on the extension of the gyrotron frequency range.