Recent activities of ITER gyrotron development in QST

QST is committed to the development of high power RF power sources (or gyrotrons) for plasma heating in fusion devices. Our main activity is the development of 170GHz gyrotron for electron cyclotron resonance heating and current drive (EC H&CD) system of ITER project which requires 20 MW of power injection into fusion plasma. In ITER, 24 sets of 1 MW gyrotrons are planned to be installed of which Japan procures 8 sets. QST (previous JAEA) has already demonstrated 1MW800s-55%, 0.8 MW-1hr-57% with the TE31,8 mode gyrotron [1] and also demonstrated >1 MW operation with TE31,11 mode gyrotron, which can generate higher power than previous design. Now the QST-ITER gyrotron has finished its designing phase and proceeds to manufacturing and test phase. The next stage of R&D activity in QST aimed multi frequency operation including >200 GHz frequency region, for future fusion devices such as DEMO. In this paper, present status of these gyrotron developments are described.