Polarization and Mode Control of EAST 140 GHz ECRH&CD System

Research activities and progress on the long pulse ECRH launcher for EAST

A long pulse Electron Cyclotron Resonance Heating (ECRH) system is developed on EAST tokamak for plasma heating and current profile tailoring. The ECRH system is designed to operate at 140GHz and to inject 4MW CW power. With respect to the physical objectives of the newly built ECRH system, a quasi-optical launcher is designed to inject 4MW continuous wave into plasma through an equatorial port. Gaussian beams delivered from evacuated corrugation waveguides will be focused and reflected by high thermal conductive metal mirrors, and then steered by using push-rod steering mechanism with entire scanning range of ±25° toroidally and over 30° poloidally in plasma cross section. The mirrors are carefully designed with mega watts power handling capability and optimum optical characteristics. The performance of steering mechanism has been tested before installation, an open-loop control system for ECRH launcher has been implemented for required mirror movement and proper polarization between plasma discharges. This paper will present the overall design and progress of the launcher, along with the performance in EAST campaigns. Considerations and possible upgrade of the design features relevant to long pulse operation are discussed.

Recent progress of the development of a long pulse 140GHz ECRH system on EAST

A long pulse ECRH system with a goal of 140GHz 4MW 100~1000s has been developed to meet the requirement of steady-state operation on EAST. Gycom gyrotrons are employed in the No.1 and No.3 systems, CPI gyrotrons are used in the No.2 and No.4 systems. The development of the two Gycom gyrotron systems has been finished. The first short pulse EC wave injection has been demonstrated successfully during the EAST 2015 Spring campaign. In the commissioning and operation towards steady-state operation, 0.4MW 100s has been injected to plasma successfully by using the No.1 system, 4.7keV 102s L-mode and 102s H-mode plasma have been achieved on EAST with the help of ECRH. Recently, a longest pulse of 0.55MW 1000s has been obtained based on calorimetric dummy load measurements on the No.3 gyrotron. The No.2 gyrotron also has been installed and partially tested, 500kW 80s has been demonstrated in the dummy load. The remaining No.4 gyrotron will be ready to test in 2018 or 2019. The whole 4MW system will be completed within two years. The 400s fully non-inductive H-mode operation would be expected in the next four years in the condition of fully tungsten diverter on EAST.

Conceptual design of CFETR ECRH equatorial launcher and upper launcher

The Electron Cyclotron Resonance Heating (ECRH) system of China Fusion Engineering Test Reactor (CFETR) is designed to inject 20 MW RF power into the plasma for heating and current drive (H&CD) applications. The ECRH system consists of 20 gyrotrons, the associated power supplies, the transmission lines and one launcher. In order to compare the launcher performance from equatorial and upper ports, two types of launcher are designed in this paper. In equatorial launcher (EL), twenty in-vessel transmission lines are divided into four groups. Every five gaussian beams from in-vessel transmission lines face one fixed focusing mirror and one steering mirror. All gaussian beams are injected into the plasma with optimal toroidal and poloidal angles calculated by C3PO/LUKE code. In upper launcher (UL), twenty-one transmission lines are supposed and divides into three groups. Every seven gaussian beams are injected into one fixed focusing mirrors and all twenty-one beams reflected to one common steering mirror finally. The optical transmission characteristics and the convergence information of gaussian beams are checked and optimized. The EL or UL is installed on the equatorial or upper port with a port-plug modular structure.