Thermomechanical optimization of actively cooled thermal shield in PIP II Cryogenic Distribution System

The PIP-II Cryogenic Distribution System (CDS) connects the cryogenic plant to the superconducting linac consisting of 23 modules. The helium stream flow through the PIP-II CDS is regulated by means of control valves located in the Distribution Valve Box. The cryomodules are supplied with helium from individual Bayonet Cans. The entire CDS process lines are shielded from the thermal radiation from the ambient vacuum jacket by actively cooled thermal shields. High efficiency of the thermal shield has been achieved by state-of-the-art optimization of its thermalization system consisting of thermal bridges connecting the shield to the high temperature helium return pipe nominally at 80 K. The temperature and stress analyses of the thermal shield have been performed numerically. The results obtained for the thermal shield of the PIP-II CDS Distribution Valve Box are compared with the solutions applied in other large science machines.