Construction progress of the Chinese First Quasi-axisymmetric Stellarator (CFQS) and preliminary experimental results on the CFQS-Test device

Abstract The Chinese First Quasi-axisymmetric Stellarator (CFQS) is being constructed as an international joint project between Southwest Jiaotong University (China) and the National Institute for Fusion Science (Japan), aiming to prove the inherent advantages of the quasi-axisymmetric (QA) magnetic configuration in confining plasmas. The CFQS project is divided into two stages. The first one focuses on testing the feasibility and accuracy of modular coils for realization of the QA topology, which is conducted on the CFQS-Test (CFQS-T) device and operated at low magnetic field strength of 0.1 T. The second stage is scheduled to delve into plasma properties of high parameters at relatively high magnetic field (1 T) in a QA stellarator. The latter stage will involve installation of dedicated support structures, such as coil cases, central poles and pillars, to withstand the strong electromagnetic force of 1 T operation. By the end of July 2024, the assembly of CFQS-T was completed with a maximum deviation of ∼2.96 mm, meeting the design requirement. Auxiliary systems, including power supply, vacuum pumping, magnetron, central control, water cooling and diagnostic systems, have also been installed and commissioned accordingly. In August 2024, the first QA magnetic configuration was successfully achieved in CFQS-T. This paper outlines the construction progress of CFQS and the preliminary experimental results attained with the CFQS-T device.