| 摘要 |
PURPOSE:To shorten the maintenance time of equipment improving the operating efficiency of cryopump by a method wherein the titled equipment is provided with a function of charging a chamber with nitrogen gas at constant flow rate. CONSTITUTION:When a cryopump 1 and an oil circulating pump 14 are in operation state, nitrogen gas 17 is introduced by means of opening a valve 11 while the chamber is being vacuumized temporarily by opening another valve 6. Besides, the temperature is controlled by means of a heater 12 and a controller 13. At this time, the pressure of nitrogen gas 17' is controlled at specific value by changing the flow rate using a needle valve 15. The heated nitrogen gas 17' left as it is can reach the corners of chamber to be released from walles 16. The released nitrogen gas flowing through the valve 6 is discharged by the oil circulating pump 14. In such a status, valves 2, 3 are closed with the valve 6 also closed to discharge the nitrogen gas inside chamber using the cryopump 1. At this time, this gas may be vacuumized at high degree without heating at high temperature since the gas adsorbed on the cryopump 1 is clean enough. |
