Thermal performance enhancement of liquid nitrogen distribution system of SST-1

The 80 K cryogenic system of SST-ITokamak facilitates the liquid nitrogen system which consists of storage tanks and a distribution system, 80 K thermal shields, current feeders system, integrated flow distribution and control system, pre-cooling heat exchangers and purifier of helium plant. Huge frosting, condensation, LN₂ dripping and vacuum level of the order of500 to 1000 mbar were observed on many sections of supply and return transfer line. The thermal cryogenic insulation as Polyurethane and Nitrile insulation has been installed. LN₂ process lines were evacuated to 10⁻³ mbar and replaced all ‘O'ring sealings. The thermal performance of insulation material has been validated at 80 K, no frosting and condensation was observed on the applied insulated vent lines and evacuated supply transfer lines. In this paper, we present the detail and selection of cryogenic insulation, design calculation, applying techniques, performances tests and its results.