Cooldown testing for the BPX central solenoid

The design basis of the cooldown objectives for the BPX (Burning Plasma Experiment) central solenoid is to determine the flow channel geometry and flow conditions which minimize the turn-to-turn differential temperature while still achieving the required cooldown time. Compressive and tensile fatigue results of the conceptual design cooling grooves are presented, showing that design requirements are expected to be achieved. Results of an earlier experimental cooling activity are also presented. Reduction of these data has yielded useful correlations in the nucleate boiling regime where T_w-T_s<110 K, and a predictive cooldown algorithm in this temperature region is described. A modified test set up incorporating better instrumentation and a more reliable test section against leaks has been fabricated and debugged. This setup is expected to yield data confirming the nucleate boiling correlations derived from the earlier work, enable determination of new correlations in the film boiling region, and permit completion of the predictive algorithm