Study of high power and high frequency gyrotron for fusion reactor

Recent progress of QST high power high frequency gyrotrons is reported. Main motivation of the high power gyrotron is the application to the plasma heating and current drive and control of the magnetic confinement fusion devices. Using a multi-frequency operation, 1 MW Gaussian beam output was obtained at four frequencies; 203 GHz (TE37,13), 170 GHz (TE31,11), 137 GHz (TE25,9), 104 GHz (TE19,7). In particular, the achievement of 203 GHz 1 MW output at 50 % will give a strong impact on the DEMO (Demonstration power plant) design. In parallel, a high frequency oscillation up to 300 GHz was studied using a short pulse gyrotron under collaboration with University of Tsukuba. In this gyrotron, 300 GHz/ 0.6 MW (TE
₃₁
,
₁₈
), 240 GHz/ 0.35 MW (TE
₂₈
,
₁₄
) oscillations were demonstrated.