Performance of the IFSMTF helium refrigerator in partial-array tests

Abstract

Performance of the International Fusion Superconducting Magnet Test Facility (IFSMTF) helium refrigerator in Partial Array Tests with three coils is described. The refrigerator was able to cool the coils and facility structure to 4.2 K in 20 days, with maximum temperature differentials of less than 50 K. Boiloff measurements were made for several components; only the lead dewars showed losses substantially higher than expected. Forced-flow cooling tests were also conducted. The coils and facility were warmed back to room temperature in 30 days. Several repairs and improvements were carried out. Results of another recent test on the refrigerator alone are reported