SPACE POWER SYSTEMS TECHNOLOGY STUDIES. RUBIDIUM EVALUATION PROGRAM. Report No. 12. Quarterly Technical Progress Report for Period November 1, 1960 through January 31, 1961

A stainless steel loop test with liquid rubidium was run for 172 hr, and the design temperature of 1510 deg F at approximately 15% vapor quality rubidium in the boiling phase was achieved. The problems of loop operation are discussed, e.g., trapped gas bubbles and argon leakage from the argon-to-water heat exchanger. The rubidium was made to boil, and its boiling point was determined to be 1325 deg F at 33 psia and 1450 deg F at 60 psia. The discrepancy between measured and literature boiling points is probably due to the fact that the thermocouples did not measure the actual rubidium temperature. The density of rubidium was measured at several temperatures from 175 to 1340 deg F and compared with literature values. (D.L.C.