Proposal of the CHS-qa experiment

The CHS experiment program started in 1988, ten years before the LHD experiment began. The purpose of this experimental program was to conduct pioneering research to learn the device operation and to develop a good perspective of the research in stellarator experiments before starting a large scale LHD experiment. When the LHD experiment was started, experimental research activities in NIFS were focused on the LHD experiment and the main target of the CHS program was shifted to the discussions for the next research target of the stellarator experiment in NIFS. NIFS organized a taskforce group to evaluate several research programs as candidates for the post-CHS project. Records of the discussions of the taskforce were included in this booklet. After making scientific comparisons between candidate plans, the experimental program of the advanced stellarator with quasi-axisymmetry was selected. The program name was decided as the CHS-qa program. This report is a copy of the official proposal of the CHS-qa which was submitted to NIFS in April, 2000. The discussions at NIFS finally reached the decision that this proposal would not be accepted as the post-CHS experiment. The main reason was that the schedule of the CHS-qa program would occur in the same period of the initial phase of the LHD experiment and it was not possible to manage the two programs in parallel. After 20 years, a new international joint project NSJP (NIFS - SWJTU Joint Project) started in 2017 for the construction of an advanced stellarator in China and to conduct experiments under the international collaboration scheme. The name of the new stellarator is CFQS (Chinese First Quasi-axisymmetric Stellarator). Because the concept of the device (quasi-axisymmetric stellarator) is the same as CHS-qa, many experiences and design data developed in the physics and the engineering design of CHS-qa are incorporated into the design work for the CFQS. The publication of the 'Proposal of the CHS-qa program' is planned now to make the information open for all researchers who will work for the new experimental program CFQS. (author)