Abstract: Systems and methods are provided for a variable cooling capacity cryocooler for a superconducting magnetic resonance imaging device having a liquid cryogen pressure vessel to provide cryogenic temperatures to a magnet assembly, a vacuum vessel surrounding the pressure vessel and a radiation shield spaced from the cryogen pressure vessel, and a pressure sensor positioned inside the cryogen pressure vessel pressure boundary for sensing pressure variations. A controller for varying the heat removal rate of the cryocooler based on the pressure variations in the cryogen pressure vessel and where the cooling capacity of the cryocooler is adjusted by modifying the speed of the electric power drive (DC or AC motors) or by changing the mechanical transmission ratio between the constant speed electric power drive and the cryocooler displacer/piston to adjust the cooler oscillating frequency of the gas flow.

Abstract: A system and method for de-icing a recondensor includes at least one heating element configured to melt iced particles from a recondensing system. A power delivery circuit is included configured to deliver power to the at least one resistive heating element such that the at least one resistive heating element delivers a supply of heat sufficient to melt the iced particles from the recondensing system.

Abstract: The zero-backflow vent assembly (100) of the present invention prevents backflow into the magnet cryogen vessel (12) and therefore eliminates magnet icing. In general, the present invention employs a spring loaded valve in the magnet vent turret (38) to prevent the influx of air after a magnet quench event. The magnet vent turret (38) is the interface between the liquid helium vessel (12) in the magnet and the atmosphere (40). A vent stack is employed to channel any cryogenic exhaust gas out of the room, normally to the outside atmosphere (40).