Cryogenic Acceptance Tests of SST-1 Superconducting Coils

Toroidal field (TF) and poloidal field (PF) coils of steady-state superconducting tokamak (SST-1) have been fully refurbished to ensure cryostable and low-dc-resistance interpancake and intercoil joints, helium leak tightness of the winding pack, and ) 10 MΩ winding pack to ground insulation resistance under cold conditions. As per SST-1 mission mandate, all TF coils and PF3 Top had been cold tested at full operational parameters. A dedicated large coil test facility was integrated for these tests. Specially adapted solutions such as magnet preparation cum transport stand, demountable busbar supports, demountable sensor mountings, reusable joints for busbar connections inside cryostat, etc., were developed. These measures led to timely and successful completion of cold tests and integration of the magnet system on to the SST-1 machine shell. The functionality of various diagnostics of the magnet system was also established during these tests. Details of coil refurbishment, test facility, test campaigns, and some important test results are reported in this paper.