Thermal analysis of the ITER TF Feeder cryogenic components

The TF Feeder delivers electricity and coolant to the superconducting TF coil, the superconducting busbar and supercritical helium pipe are all work at 4K. Without proper thermal insulation designs, the heat load from room environment will make it impossible to keep the busbar and the coil superconducting, thus numerous and accurate thermal analyses are performed to verify the design. It is vacuum inside the Feeder chambers, and the heat load mainly comes from the support conduction and the thermal radiation; 80K thermal shield, thermal intercept and low thermal conductivity support material are employed to minimize the heat load. Since the Feeder is a huge structure over 10m in length, it costs time for it to be cooled down, there must be a delay compared to the active cooled TF coils. Therefore, the cool down time is also researched in this paper.