Results of Vacuum-Pressure Impregnation of the PF1 Coil Ground Insulation

The paper describes the vacuum-pressure impregnation (VPI) of ground insulation of the ITER PF1 coil carried out in the Russian Federation in 2021. The ITER Organization imposes extremely high requirements on mechanical and dielectric strength of the electrical insulation of the superconducting coils because of different nature of stresses in the ITER machine. The VPI method is typically used to make insulation monolithic and durable. The method has been developed for VPI of large complex-shaped large-sized coils 9 m in outer diameter and about 160 t in weight. The thermal scenario corresponding to the temperature distribution within +/−5 degrees and compound pot life is defined by the FEM analysis. Basing on this analysis, outer heaters with the required power output have been designed. The double-wall mould design has been developed to provide uniform distribution of epoxy resin and uniform mechanical compression of the insulation surface. The VPI of PF1 was carried out by DGEBA epoxy resin system by the above-described method. Thereafter, a number of tests have been performed. The VPI method and the test results are described in detail below.