Abstract: A Gifford-McMahon cryogenic refrigerator comprises a reciprocating displacer within a refrigeration volume. The displacer is pneumatically driven by a drive piston within a pneumatic drive volume. Pressure in the pneumatic drive volume is controlled by valving that causes the drive piston to follow a programmed displacement profile through stroke of the drive piston. The drive valving may include a proportional valve that provides continuously variable supply and exhaust of drive fluid. In a proportionally controlled feedback system, the valve into the drive volume is controlled to minimize error between a displacement signal and a programmed displacement profile. Valving to the warm end of the refrigeration volume may also be proportional. A passive force generator such as a mechanical spring or magnets may apply force to the piston in opposition to the driving force applied by the drive fluid.

Abstract: A Gifford-McMahon cryogenic refrigerator comprises a reciprocating displacer within a refrigeration volume. The displacer is pneumatically driven by a drive piston within a pneumatic drive volume. Pressure in the pneumatic drive volume is controlled by valving that causes the drive piston to follow a programmed displacement profile through stroke of the drive piston. The drive valving may include a proportional valve that provides continuously variable supply and exhaust of drive fluid. In a proportionally controlled feedback system, the valve into the drive volume is controlled to minimize error between a displacement signal and a programmed displacement profile. Valving to the warm end of the refrigeration volume may also be proportional. A passive force generator such as a mechanical spring or magnets may apply force to the piston in opposition to the driving force applied by the drive fluid.

Abstract: A Gifford-McMahon cryogenic refrigerator comprises a reciprocating displacer within a refrigeration volume. The displacer is pneumatically driven by a drive piston within a pneumatic drive volume. Pressure in the pneumatic drive volume is controlled by valving that causes the drive piston to follow a programmed displacement profile through stroke of the drive piston. The drive valving may include a proportional valve that provides continuously variable supply and exhaust of drive fluid. In a proportionally controlled feedback system, the valve into the drive volume is controlled to minimize error between a displacement signal and a programmed displacement profile. Valving to the warm end of the refrigeration volume may also be proportional. A passive force generator such as a mechanical spring or magnets may apply force to the piston in opposition to the driving force applied by the drive fluid.

Abstract: A Gifford-McMahon cryogenic refrigerator comprises a reciprocating displacer within a refrigeration volume. The displacer is pneumatically driven by a drive piston within a pneumatic drive volume. Pressure in the pneumatic drive volume is controlled by valving that causes the drive piston to follow a programmed displacement profile through stroke of the drive piston. The drive valving may include a proportional valve that provides continuously variable supply and exhaust of drive fluid. In a proportionally controlled feedback system, the valve into the drive volume is controlled to minimize error between a displacement signal and a programmed displacement profile. Valving to the warm end of the refrigeration volume may also be proportional. A passive force generator such as a mechanical spring or magnets may apply force to the piston in opposition to the driving force applied by the drive fluid.

Abstract: A cryopump includes a refrigerator with at least first and second stages. A radiation shield surrounds the second stage and is in thermal contact with the first stage. The radiation shield includes a drain hole to permit cryogenic fluid to traverse through the drain hole during regeneration. The cryopump also includes a primary pumping surface supporting adsorbent in thermal contact with the second stage. The second stage array assembly includes a primary condensing surface, protected surfaces having adsorbent, and non-primary condensing surfaces. A baffle is disposed over the drain hole. The baffle redirects gas from an annular space disposed between the radiation shield and the vacuum vessel that attempts to traverse through the drain hole to prevent the gas from condensing on a non-primary condensing surface. The baffle directs gas to condense on the primary condensing surface.

Abstract: A cryopump includes a refrigerator with at least first and second stages. A radiation shield surrounds the second stage and is in thermal contact with the first stage. The radiation shield includes a drain hole to permit cryogenic fluid to traverse through the drain hole during regeneration. The cryopump also includes a primary pumping surface supporting adsorbent in thermal contact with the second stage. The second stage array assembly includes a primary condensing surface, protected surfaces having adsorbent, and non-primary condensing surfaces. A baffle is disposed over the drain hole. The baffle redirects gas from an annular space disposed between the radiation shield and the vacuum vessel that attempts to traverse through the drain hole to prevent the gas from condensing on a non-primary condensing surface. The baffle directs gas to condense on the primary condensing surface.

Abstract: A single ducted valve assembly provides an integrated cryopump valve having a purge valve port connecting the assembly to a cryopump with a coaxial connection having an inner duct and an outer duct. A pressurized gas interface connects a pressurized gas source to the cryopump through the inner duct. A rough valve port can connect the outer duct of the assembly to a rough vacuum pump; and a relief valve port can connect the outer duct of the assembly to an exhaust stack.

Abstract: A single ducted valve assembly provides an integrated cryopump valve having a purge valve port connecting the assembly to a cryopump with a coaxial connection having an inner duct and an outer duct. A pressurized gas interface connects a pressurized gas source to the cryopump through the inner duct. A rough valve port can connect the outer duct of the assembly to a rough vacuum pump; and a relief valve port can connect the outer duct of the assembly to an exhaust stack.

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 T-shaped manifold employs a single multiway control valve for purging and charging a cryogenic system of interest. The single multiway control valve is positioned at the intersection of a crossbar and perpendicular elongate member. One end of the crossbar is associated with a source of working gas. the opposite end of the crossbar provides a purge or check valve outlet. One end of the elongate member is connected to the multiway control valve and an opposite end is coupled by a VCO fitting to the cryogenic system of interest. At one setting, the single multiway control valve provides working gas to the system through the one end of the crossbar and elongate member. At a second setting, the multiway control valve allows gas to be vented from the system to ambient through the elongate member and the purge valve outlet. An in-line pressure gauge connected to the elongate member provides an indication of ingoing flow as well as outgoing flow of gas during respective charging and purging of the system.