Abstract: In a power failure recovery, the operating state before a power failure and present conditions of a cryopump are determined to initiate a regeneration or startup process. Where the refrigerator was operating before power failure, it is turned on during recovery to condense gases in the cryopump. A startup process is initiated where the cryopump was in a startup process before the power failure and present conditions of the cryopump indicate that the cryopump is sufficiently empty or clean. If the operating state and present conditions indicate that a corrosive or hazardous liquid remains in the cryopump, a regeneration process is initiated. If the cryopump was in a shutdown process before the power failure, the cryopanel of the cryopump is refrigerated to a temperature at which gases sublimate from the cryopanel. The temperature of the cryopanel is then maintained until the gases are removed.

Abstract: In a power failure recovery, the operating state before a power failure and present conditions of a cryopump are determined to initiate a regeneration or startup process. Where the refrigerator was operating before power failure, it is turned on during recovery to condense gases in the cryopump. A startup process is initiated where the cryopump was in a startup process before the power failure and present conditions of the cryopump indicate that the cryopump is sufficiently empty or clean. If the operating state and present conditions indicate that a corrosive or hazardous liquid remains in the cryopump, a regeneration process is initiated. If the cryopump was in a shutdown process before the power failure, the cryopanel of the cryopump is refrigerated to a temperature at which gases sublimate from the cryopanel. The temperature of the cryopanel is then maintained until the gases are removed.

Abstract: The present invention provides a cryopump coupled to a gate valve in which the gate valve is automatically prevented from being opened during unsafe conditions, for example, when combustible gases such as hydrogen may be present in the cryopump, but may be operated during safe conditions. A method of controlling the gate valve includes automatically determining with a controller whether the cryopump is operating in one of safe and unsafe conditions. The unsafe conditions are situations where combustible gas may be present in the cryopump and may be correlated to parameters of the cryopump including operational modes of the cryopump, and sensed parameters. The gate valve is automatically controlled with the controller based on the determination of safe and unsafe conditions. The gate valve is automatically locked closed during unsafe conditions and remains locked until the unsafe conditions are removed.

Abstract: A cryopump is regenerated by roughing the cryopump during purging. Purging and roughing is carried out in first a high temperature mode and then a lower ambient temperature mode. In the lower temperature mode, the cryogenic refrigerator is turned on. If the system fails a rough test after roughing at the lower temperature, it is repurged with the rough valve open.

Abstract: A method for regulating the cooldown of multiple cryogenic refrigerators supplied with compressed refrigerant from a common compressor includes the following steps. The cooldown of the refrigerators is monitored. The cooldown of at least one refrigerator is then governed to regulate the gas flow distributed from the compressor to each of the refrigerators to enhance the cooldown of an individual refrigerator. Governing a refrigerator to achieve the objectives of this method can be achieved by various processes. These processes include supplying heat to the refrigerator, slowing the speed of the displacer in the refrigerator, halting the motion of the displacer, and profiling the speed of the displacer as a function of the first and second-stage temperatures.

Abstract: In a fast partial regeneration process, the second stage of a cryopump is heated as purge gas is applied to the cryopump. In a test loop, the purge gas is turned off and the roughing valve is opened. If the cryopump is judged to be sufficiently empty of gases from the second stage by being roughed to a sufficiently low pressure in a short period of time the system proceeds to a reconditioning phase. If the system fails the test, however, it is repurged with a burst of warm purge gas and then retested. After passing the emptiness test, the pressure is further reduced by the roughing pump as heat is applied to the second stage. The heat is then turned off for cool down as the system continues to be rough pumped to a base pressure. At about the base pressure, the roughing valve is cycled to maintain the cryopump pressure at a level near to the base pressure.

Abstract: Condensation on a cryopump second stage refrigerator cylinder is prevented by arranging a passageway between a colder second stage cylinder shield in thermal contact with the coldest section of the second stage and a warmer radiation shield in thermal contact with the warmer first stage. This arrangement produces a uniform and significant temperature differential in the passageway. The passageway is arranged so that the ratio of its length, L, to its width, W, is ideally greater than five. This ensures molecular collisions with the cold surface of the cylinder shield so that gas molecules are tightly bound to the cylinder shield. As a result, condensation on the refrigerator cylinder and resultant pressure variations are prevented.

Abstract: A self-cleaning pressure relief valve has a spring-biased valve closure with an annular contact edge which makes contact with an o-ring to seal the valve. The annular contact edge is slightly larger in radius than the central radius of the o-ring so that changing pressure on the closure causes the contact edge to slide along the surface of the o-ring.