Progress of high power 170 GHz gyrotron in JAEA

Recent progress on the high power gyrotron development in JAEA is presented. The gyrotron is featured to have a triode-type magnetron injection gun, a cylindrical resonator working at 170 GHz with TE 31,8 mode, a water-cooled diamond window and a depressed collector. After the demonstration of the ITER basic performance, the gyrotron has been operated for 3 years, and recorded ∼200 GJ of total output energy. Next, a gyrotron which oscillates in higher order resonator mode, TE 31,12 , is designed and fabricated to study the long pulse oscillation at greater than 1 MW. In parallel, feasibility studies of a CW-power modulation for neoclassical tearing mode stabilization, a dual frequency gyrotron and a rapid frequency control are carried out. It is shown that these gyrotrons will be available with current technology.