Abstract: A refrigeration system includes a dewar and a refrigerator/liquefier which meets the variable demands of a superconducting magnet within the dewar. The system is sized to meet average loads over a defined duty cycle, and is variably operable to meed demands. In the preferred embodiment, a first supply of fluid circulates through a "condenser" element positioned in a dewar ullage to liquefy a separate supply of fluid in the dewar, and to refrigerate a pulsed cryogenic load therein, such as a superconducting magnet. A portion of the first supply of fluid may be diverted to refrigerate a second pulsed cryogenic load, such as magnet current leads permanently connected to the magnet. The dewar includes a cold gas vapor storage chamber separate from the dewar ullage, and the chamber is preferably located within the inner core of a solenoid superconducting magnet for compact and thermally efficient design. Responsive, independent adjustment of refrigeration to pulsed cryogenic loads is made possible.

Abstract: A refrigeration system includes a dewar and a refrigerator/liquefier which meets the variable demands of a superconducting magnet within the dewar. The system is sized to meet average loads over a defined duty cycle, and is variably operable to meed demands. In the preferred embodiment, a first supply of fluid circulates through a "condenser" element positioned in a dewar ullage to liquefy a separate supply of fluid in the dewar, and to refrigerate a pulsed cryogenic load therein, such as a superconducting magnet. A portion of the first supply of fluid may be diverted to refrigerate a second pulsed cryogenic load, such as magnet current leads permanently connected to the magnet. The dewar includes a cold gas vapor storage chamber separate from the dewar ullage, and the chamber is preferably located within the inner core of a solenoid superconducting magnet for compact and thermally efficient design. Responsive, independent adjustment of refrigeration to pulsed cryogenic loads is made possible.

Abstract: An expansion engine incorporates various structural features in which all cold seals are stationary, and only warm seals move. Moving parts which are subject to cryogenic temperatures are designed with gas bearings, while tight tolerances and material choices inhibit wear and steady state heat loss. Numerous other features include structural design to relieve stresses, combined fabrication of key parts, initial bias of the inlet and outlet valves which contract on cooldown to desired alignment, and a gas-purged upper seal housing, eliminate various sources of expansion engine failure and heat loss during operation and result in high reliability and thermal efficiency.

Abstract: A refrigeration system includes a dewar and a refrigerator/liquefier which meets the variable demands of a superconducting magnet within the dewar. The system is sized to meet average loads over a defined duty cycle, and is variably operable to meed demands. In the preferred embodiment, a first supply of fluid circulates through a "condenser" element positioned in a dewar ullage to liquefy a separate supply of fluid in the dewar, and to refrigerate a pulsed cryogenic load therein, such as a superconducting magnet. A portion of the first supply of fluid may be diverted to refrigerate a second pulsed cryogenic load, such as magnet current leads permanently connected to the magnet. The dewar includes a cold gas vapor storage chamber separate from the dewar ullage, and the chamber is preferably located within the inner core of a solenoid superconducting magnet for compact and thermally efficient design. Responsive, independent adjustment of refrigeration to pulsed cryogenic loads is made possible.