Advances in technology and high power performance of the ECH system on DIII-D

The gyrotron complex on DIII-D has been updated and consists of six gyrotrons installed and routinely operating reliably for injection of up to 3.6 MW into the plasma. The eight sets of real time steerable mirrors that are installed on DIII-D inject the rf power from the tokamak low field side. The transmission line was upgraded with new rf power monitors at the last miter bend before the tokamak, which can measure wave polarization, mode content, and rf power reflected from the plasma. A new design depressed collector gyrotron in the 1.5 MW class, operating at 117.5 GHz, is expected to be installed in 2017. Plans call for an expansion of the ECH system to ten gyrotrons.