Gyrotron operation during the first W7-X campaign-handling and reliability

Electron Cyclotron Resonance Heating (ECRH) is the main heating system for steady-state operation and was the only available heating system during the first operational phase (OP1.1) of the W7-X stellarator [1]. The ECRH was used for different tasks at W7-X such as wall conditioning, controlled plasma start-up from the neutral gas up to steady state plasma control [2] and performance optimization by temperature profile shaping. The ECRH plant was equipped with 7 gyrotrons and 6 of them were operational. The quasi optical transmission line was precisely adjusted in preparation of OP1.1. The operational experience of the ECRH plant will be discussed.