Progress of high power and long pulse ECRH system in EAST

Abstract

In accordance with the long pulse objectives of the Experimental Advanced Superconducting Tokamak (EAST), an electron cyclotron resonance heating (ECRH) system with the feature of 4MW power for a pulse length up to 1000s at 140GHz, using second harmonic of the extraordinary mode (X2) is presently under construction at the institute of plasma physics, Chinese academy of sciences (ASIPP). The missions of the system are to provide central heating, current drive, plasma profile tailoring and control of magneto-hydrodynamic (MHD) instabilities. The continuous wave (CW) power is transmitted from the gyrotrons to EAST via low-loss evacuated waveguide transmission lines. Considering the diverse applications of the EC system, the front steering launcher is designed to inject four individually steered beams across nearly the entire plasma cross section. The beam's launch angles can be continuously varied with the optimized scanning range of over 30° in poloidal direction and ±25° in toroidal, as well as the polarization will be adjusted during the discharge by the orientations of a pair of polarizers in the transmission line to maintain the highest absorption for different operational scenarios. The commissioning of the first 2MW system will be commenced in the end of 2014.