High Power and Long Pulse ECRF System in JT-60U

A I l0 GHz 3 MW Electron Cyclotron Range of Frequency (ECRF) heating system in JT-60U is presented. A I MW ECRF line was constructed at March in 1999 and a construction of the other two ECRF lines of 2 MW will be started from spring in 2000. The system is featured by a I MW gyrotron per a line which is designed to be operated more than 5 second. The antenna with two mirrors is designed to steer the RF power injection position from plasma center to edge during a shot. The polarization is optimized by a pair of polarizers by real time control. Temperature rise of RF components after high power and several second operation was demonstrated. The effective control of narrow RF deposition and polarization was also demonstrated.