Development and Preliminary Commissioning Results of a Long Pulse 140 GHz ECRH System on EAST Tokamak (Invited)

A long pulse electron cyclotron resonance heating (ECRH) system has been developed to meet the requirements of steady-state operation for the EAST superconducting tokamak, and the first EC wave was successfully injected into plasma during the 2015 spring campaign. The system is mainly composed of four 140 GHz gyrotron systems, 4 ITER-Like transmission lines, 4 independent channel launchers and corresponding power supplies, a water cooling, control and inter-lock system etc. Each gyrotron is expected to deliver a maximum power of 1 MW and be operated at 100-1000 s pulse lengths. The No.1 and No.2 gyrotron systems have been installed. In the initial commissioning, a series of parameters of 1 MW 1 s, 900 kW 10 s, 800 kW 95 s and 650 kW 753 s have been demonstrated successfully on the No.1 gyrotron system based on calorimetric dummy load measurements. Significant plasma heating and MHD instability suppression effects were observed in EAST experiments. In addition, high confinement (H-mode) discharges triggered by ECRH were obtained. (paper)