Integrated Commissioning Test of JT-60SA Magnet and Cryogenic Systems:

From Superconducting Coil Repair to Integrated Commissioning Test Initiation

Abstract

JT-60SA is the largest Tokamak fusion experimental device worldwide, with a superconducting magnet system. JT-60SA comprises 18 toroidal field （TF） coils, six equilibrium field （EF） coils, and four central solenoid （CS） modules. Tokamak assembly was completed in March 2020. The cooldown of the magnet system for the integrated commissioning test and the individual magnet energization test began in October 2020. TF coil achieved 100 % current （25.7 kA） operation, and EF2~6 and CS1~4 achieved ± 5 kV operation. However, EF1 caused a double grounding fault in the high voltage energization test and was electrically shorted. The incident was investigated, followed by repair and reinforcement of insulation. It took approximately 2 years to develop the insulation reinforcement procedures and high voltage tests in vacuum conditions and complete the reinforcement of the insulation and high voltage tests, allowing us to achieve the first plasma operation. This paper describes the magnet and cryogenic systems, recovery activities after the EF1 incident, and the integrated commissioning test preparation.