Study of sub-terahertz high power gyrotron for ECH&CD system of DEMO

For the Electron cyclotron resonance heating and current drive (ECH&CD) system on fusion DEMO reactor, the high power mm-wave of 200 GHz ∼300 GHz is expected. To increase the gyrotron frequency, extremely high-order oscillation mode should be adopted to suppress the Ohmic loss on the resonator wall less than ∼20 MW/m
²
. Here, we designed and fabricated a 300 GHz gyrotron of TE
32,18
mode oscillation and started a short pulse experiment to investigate the oscillation characteristics of the high order mode at ∼300 GHz. As a preliminary result, we demonstrated the power generation of ∼0.5 MW at ∼300 GHz oscillation at the oscillation mode of TE
32,18
, and other modes.