Configuration characteristics of the Chinese First Quasi-axisymmetric Stellarator

• Published in: Nuclear fusion 2021-01, Vol.61 (1), p.16014
• Main Authors: Liu, Haifeng, Shimizu, Akihiro, Xu, Yuhong, Okamura, Shoichi, Kinoshita, Shigeyoshi, Isobe, Mitsutaka, Li, Yangbo, Xiong, Guozheng, Wang, Xianqu, Huang, Jie, Cheng, Jun, Liu, Hai, Zhang, Xin, Yin, Dapeng, Wang, Y, Murase, Takanori, Nakagawa, Sho, Tang, Changjian
• Format: Article
• Language: English
• Subjects: MHD stability; Quasi-axisymmetric configuration; Stellarator design
• ISSN: 0029-5515; 1741-4326
• DOI: 10.1088/1741-4326/abbc85

The Chinese First Quasi-axisymmetric Stellarator (CFQS) will be the first operational quasi-axially symmetric stellarator in the world. The physical and engineering complexities led to the cancellation of two famous quasi-axisymmetric stellarators, CHS-qa and NCSX. Therefore, the major mission of the CFQS is to experimentally achieve the canonical quasi-axisymmetric configuration. The CFQS has been designed to possess a number of advanced features in fixed and free-boundary equilibria. It is a compact stellarator with an aspect ratio R/a ∼4.0. The neoclassical diffusion coefficient is similar to that of tokamaks in the collisionless regime. The MHD equilibrium of the CFQS configuration is stable up to volume-averaged normalized pressure β ∼1.1%. A region of the second ballooning stability exists in this facility with a large region of plasma, becoming second stable for β ∼2.7% in free-boundary equilibria. The gap between the first and second stability boundaries is very narrow, which is greatly beneficial for the CFQS operation in the second stable regime with high β plasma. A modular coil system with 16 coils is designed which robustly reproduces the standard quasi-axisymmetric magnetic field.