Consideration and research of hybrid heating method in VPI for CFETR PF coils

The poloidal field (PF) coils are one of the CFETR magnet system which winding by CICC conductor. In order to meet the design requirements of demanding, the coil insulation shall be processed by vacuum pressure impregnation (VPI). After the resin impregnating the coil insulation, a subsequent high temperature cure is imposed for a relatively long period of time to fully cure the resin throughout the insulation. During the curing, the temperature must be controlled even on whole coil. All CFETR PF coil are fabricated by stacking several double-pancakes (DP), due to the complex structure, the common outer heating method can hardly satisfy the curing temperature requirement. So an inner heating which assisted by common outer heating (hybrid heating) method was researched. The experiment results shows under hybrid heating method, the curing temperature on the coil insulation can guaranteed even and the insulation quality can satisfy design requirement.