Recent developments in engineering design for the quasi-axisymmetric stellarator CFQS
A. Shimizu, Shigeyoshi Kinoshita, M. Isobe, S. Okamura, K. Ogawa, M. Nakata, Y. Yoshimura, C. Suzuki, M. Osakabe, Takuhei Murase, Setsuko Nakagawa, H. Tanoue, Yuhong Xu, Haifeng Liu, Hai Liu, Jie Huang, Xianqu Wang, J. Cheng, Guozhen Xiong, C. J. Tang, Dawei Yin, Y. X. Wan
Abstract
Abstract A quasi-axisymmetric stellarator, the CFQS, has been designed as a joint project of the National Institute for Fusion Science and Southwest Jiaotong University to prove intrinsic advantages of quasi-axisymmetry. Principal parameters of the CFQS are as follows: the major radius is 1 m, the magnetic field strength is 1 T, the aspect ratio is 4, and the toroidal periodic number is 2. The magnetic field configuration is designed based on that of the CHS-qa. Enhanced confinement properties within the context of neoclassical theory are achieved by its quasi-axisymmetric configuration. In the entire radial range, the magnetic well is retained to keep favourable stability features in the magnetohydrodynamic equilibrium. A magnetic field coil system was designed for the CFQS, which consists of 16 modular coils, 12 toroidal field coils, and 4 poloidal field coils. The supporting structure is designed to withstand strong electromagnetic force under 1 T operation, maintaining enough space for heating and diagnostic systems. The mock-up modular coil with the most complicated shape was constructed by Hefei Keye Electro Physical Equipment Manufacturing Co., Ltd. to check manufacturability and the achieved accuracy. A heat-run test was performed to check the temperature rise of conductors, and the capability of 1 T operation was confirmed. After various tests for the mock-up coil, construction of actual modular coils and the vacuum vessel has begun.