Measurement of Cryopanel Temperature and Pump Performance of Cryopump using Flow Meter Method

In this research, six silicon diode cryogenic temperature sensors are put on the cryopanels of the first- and second-array of the two-stage Gifford-McMahon (G-M) closed-loop gaseous helium cryopump, ULVAC-10PU. The temperatures of the cryopanel of the pump during start-up, shut off; and the introduction of nitrogen and argon gases are measured according to Welch's recommended practices. The results show that the pump reaches the ultimate pressure of Pa after the system has been running for 341 minutes, and the temperatures of first-stage and second-stage array are at 80K and between 28.2~37.8K, respectively. The temperatures of the first-stage and the second-stage array reach 291K and 288.8~291.4K after the system is shut off for 550 minutes. The pumping speeds of nitrogen and argon are liters/sec and 1,770~3,680 liters/sec, respectively. As the throughputs of nitrogen and argon exceed 63 and 62 SCCM, respectively, the array temperatures significantly increase. When the throughputs of nitrogen and argon achieve maximums of 338 and 341 SCCM, the temperature of the first-stage array reaches 98.6K and 111K, respectively, and the temperature of the second-stage array reaches from 32.7~39.0K and from 31.7~40.0K, respectively.