Progress of engineering design of CFETR vacuum systems

Abstract

Vacuum systems for the China Fusion Engineering Test Reactor (CFETR), including pumping system, fueling system, wall conditioning, as well as their control systems, are required to achieve high vacuum, effective plasma fueling, and good wall condition for steady-state plasma operation and to facilitate remote flexible control with high reliability to ensure safe operation. In the last few years, based on the requirements of vacuum systems and subsystems of CFETR, their features and challenges have been analysed, basic parameters have been defined, and preliminary designs have been developed. Herein, nine cryopumps with pumping speed of 68 m³/s for D2 in a molecular flow regime are proposed for use in a torus vacuum chamber to achieve vacuum pressure <1.0 × 10−5 Pa before plasma operation. The throughput of the torus pumping system is designed to be >290 Pa•m³•s−1 to meet the requirement of steady-state operation of CFETR discharge. Pellet injectors and the gas injection system for seeding the fuel and impurity gas and wall conditionings, including baking, GDC, and ICRF-DC, for removal of hydrogen isotopes/impurities of the torus vacuum are also designed. Moreover, integrated design of vacuum systems and space layout of all subsystems are also investigated.