Commissioning of the extended multi-frequency ECRH system at ASDEX upgrade

Two gyrotrons have recently been installed in the multi-megawatt Electron Cyclotron Resonance Heating (ECRH) system at the ASDEX Upgrade (AUG) tokamak. They are part of a new system that replaces an older ECRH system which was operating since 1996. The new two-frequency gyrotrons operating at AUG at 105 and 140 GHz (10 s pulse length with output powers close to 1 MW) are part of an upgrade with four gyrotrons in total which will double the installed ECRH power at AUG. After completion the system will have around 6.5–7 MW at 140 GHz (or 5.5 MW at 105 GHz) from 8 units available in the plasma during the whole AUG discharge flattop time (10 s).