ECRH with 10 gyrotrons at W7-X – achievements and enhancements

Electron Cyclotron Resonance Heating (ECRH) was the main heating system during the operation campaign OP1.2b in 2018 of the W7-X stellarator [1]. The steady state capable ECRH system was used for plasma start-up, X-mode and O-mode heating as well as current drive (ECCD). The ECRH plant is equipped with 10 operational 140 GHz gyrotrons and a quasi-optical transmission line, which is operated under standard atmosphere conditions. The achieved plasma parameters with respect to the performance of the ECRH plant and prospective enhancements will be discussed.