Study on Electrical Tests of Superconducting Busbar Protection Insulation of ITER Feeder PF4 CFT

Poloidal field coil no. 4 (PF4) cryostat feedthrough (CFT) is a key subcomponent of ITER feeder system. The superconducting busbars of PF4 CFT have insulation protection layer, which consists of several half-overlapped pre-preg and glass Kapton for main structure. Base on the special busbar structure, how to do the electrical tests for production final acceptance was studied. In this paper, three kinds of electrical tests for PF4 CFT busbar insulation acceptance were introduced, include direct current high-voltage test, alternating current partial discharge test, and Paschen test. On-site environment control, electrodes connection configuration, and some detail processes of these electrical tests were introduced. Some test results of leakage current were showed in this paper to guarantee the high quality of PF4 CFT superconducting busbar protection insulation.