Research on Performance of Vacuum Coupling Radius Seals of HL-2M Divertor in Operation

HL-2M device is a new tokamak under construction. The baking temperature of the vacuum vessel and its in-vessel components is approximately 300 °C. The vacuum coupling radius seals (VCR) which are employed as the in-vessel sealing joints of the cooling circuits for HL-2M divertor are also as the vacuum boundary, their leak rate must be less than 10−9 Pa m3/s. To ensure the VCR sealing performance, the leak tightness tests on VCR are performed. This paper presents the effects of the gaskets material, the heating rate and the torque on the sealing performance of VCR. The results show that the 316L stainless steel as the gaskets materials of VCR gets the best performance for HL-2M divertor in operation. And the slower the heating rate is, the better the leak tightness is. The torque for VCR is at least 200 N m to satisfy its sealability during HL-2M divertor operation, especially baking.