Abstract: A superconducting magnet (10) includes a cryogenic container (22, 32) containing a superconducting magnet winding (20). A sealed electrical feedthrough (36) passes through the cryogenic container. A contactor (40) inside the cryogenic container has an actuator (42) and feedthrough-side and magnet-side electrical terminals (46, 47). A high temperature superconductor (HTS) lead (60) also disposed in the cryogenic container has a first end (62) electrically connected with the magnet-side electrical terminal of the contactor and a second end (64) electrically connected to the superconducting magnet winding. A first stage thermal station (52) thermally connected with the first end of the HTS lead has a temperature (T1) lower than the critical temperature (TC,HTS) of the HTS lead. A second stage thermal station (54) thermally connected with the second end of the HTS lead has a temperature (T2) lower than a critical temperature (TC) of the superconducting magnet winding (20).

Abstract: A superconducting magnet includes a liquid helium reservoir (14), superconducting magnet windings (12) disposed in the liquid helium reservoir, and a vacuum jacket (20) surrounding the liquid helium reservoir. A cold head (30) passes through the vacuum jacket. The cold head has a warm end (32) welded to an outer wall (22) of the vacuum jacket and a cold station (46) disposed in the liquid helium reservoir. A heat exchanger (60) is disposed inside the vacuum jacket and secured to or integral with the cold head. The heat exchanger includes a fluid passage (62) having an inlet (64) in fluid communication with the liquid helium reservoir and having an outlet (66) in fluid communication with ambient air. While the cold head is turned off, gas helium flows from the liquid helium reservoir to ambient air via the heat exchanger, thereby cooling the non-operating cold head.

Abstract: An apparatus (100) includes: an outer shell (211); an inner vessel (212) disposed within the outer shell; a cold head (260) having a first stage (261) disposed within the outer shell, and having a second stage (262) for contacting an interior of the inner vessel; a vent (215) extending from the interior of the inner vessel to the exterior of the outer shell; first and second heat exchangers (302a, 302b); a first thermal shield (213) disposed between the inner vessel and the outer shell; and a second thermal shield (214) disposed between the inner vessel and the first thermal shield. The first thermal shield is thermally connected to the first stage of the cold head and the first heat exchanger and is thermally isolated from the inner vessel and outer shell. The second thermal shield is thermally connected to the second heat exchanger and is thermally isolated from the inner vessel, outer shell, first thermal shield, and cold head.

Abstract: A superconducting magnet includes a liquid helium reservoir (14), superconducting magnet windings (12) disposed in the liquid helium reservoir, and a vacuum jacket (20) surrounding the liquid helium reservoir. A cold head (30) passes through the vacuum jacket. The cold head has a warm end (32) welded to an outer wall (22) of the vacuum jacket and a cold station (46) disposed in the liquid helium reservoir. A heat exchanger (60) is disposed inside the vacuum jacket and secured to or integral with the cold head. The heat exchanger includes a fluid passage (62) having an inlet (64) in fluid communication with the liquid helium reservoir and having an outlet (66) in fluid communication with ambient air. While the cold head is turned off, gas helium flows from the liquid helium reservoir to ambient air via the heat exchanger, thereby cooling the non-operating cold head.

Abstract: A superconducting magnet comprises a liquid helium reservoir (14), superconducting magnet windings (12) disposed in the liquid helium reservoir, vacuum jacket walls (20, 22, 26) containing a vacuum volume (24) surrounding the liquid helium reservoir, and a thermal shield (30) disposed in the vacuum volume and surrounding the liquid helium reservoir. A thermal bus (50) is secured to the thermal shield. The thermal bus includes an integral heat exchanger comprising a fluid passage (60) passing through the thermal bus. An inlet fluid conduit (62) connects the liquid helium reservoir with an inlet of the fluid passage, and an outlet fluid conduit (64) connects an outlet of the fluid passage with ambient air. The thermal bus (50) is connected to the first stage cold station of a cold head (40) by a thermally conductive connection (46).

Abstract: An apparatus includes an electrically conductive coil which produces a magnetic field when an electrical current passes therethrough; a selectively activated persistent current switch connected across the electrically conductive coil; a cryostat having the electrically conductive coil and the persistent current switch disposed therein; an energy dump; at least one sensor which detects an operating parameter of the apparatus and outputs at least one sensor signal in response thereto; and a magnet controller. The magnet controller receives the sensor signal(s) and in response thereto detects whether an operating fault (e.g. a power loss to the compressor of a cryocooler) exists in the apparatus, and when an operating fault is detected, connects the energy dump unit across the electrically conductive coil to transfer energy from the electrically conductive coil to the energy dump unit. The energy dump unit disperses the energy outside of the cryostat.

Abstract: A superconducting magnet system, including a cryostat, and a ride-through system for the superconducting magnet system include: one or more gravity-fed cooling tubes configured to have therein a cryogenic fluid; a first heat exchanger configured to transfer heat from the one or more gravity-fed cooling tubes to a cryocooler; a storage device having an input connected to the first heat exchanger and configured to receive and store a boiled-off gas from the first heat exchanger; and a thermal regenerator having an input connected to the output of the storage device.

Abstract: A superconducting magnet (10) includes a cryogenic container (22, 32) containing a superconducting magnet winding (20). A sealed electrical feedthrough (36) passes through the cryogenic container. A contactor (40) inside the cryogenic container has an actuator (42) and feedthrough-side and magnet-side electrical terminals (46, 47). A high temperature superconductor (HTS) lead (60) also disposed in the cryogenic container has a first end (62) electrically connected with the magnet-side electrical terminal of the contactor and a second end (64) electrically connected to the superconducting magnet winding. A first stage thermal station (52) thermally connected with the first end of the HTS lead has a temperature (T1) lower than the critical temperature (TC,HTS) of the HTS lead. A second stage thermal station (54) thermally connected with the second end of the HTS lead has a temperature (T2) lower than a critical temperature (TC) of the superconducting magnet winding (20).

Abstract: An MRI system is provided with a refrigeration system that includes dual compressors that are coupled to a single coldhead that cools the liquid helium in the MRI system. Because the single coldhead receives the compressed refrigerant regardless of the compressor that is being used, the unacceptable cooling loss that would have occurred with redundant coldheads is avoided. By coupling two compressors to a single coldhead, continuous operation can be provided despite a failure of either compressor. The dual refrigeration system may comprise a water-cooled compressor and an air-cooled compressor to enhance MRI system reliability in the event of a failure of the primary compressor or the cooling water circulation system. Alternatively, two water-cooled compressors may be provided, each with its own independent water system. Check valves may be used to enable passive control of the refrigerant gas flow from either compressor to the coldhead, thereby further improving the reliability.

Abstract: An apparatus (100) includes: an outer shell (211); an inner vessel (212) disposed within the outer shell; a cold head (260) having a first stage (261) disposed within the outer shell, and having a second stage (262) for contacting an interior of the inner vessel; a vent (215) extending from the interior of the inner vessel to the exterior of the outer shell; first and second heat exchangers (302a, 302b); a first thermal shield (213) disposed between the inner vessel and the outer shell; and a second thermal shield (214) disposed between the inner vessel and the first thermal shield. The first thermal shield is thermally connected to the first stage of the cold head and the first heat exchanger and is thermally isolated from the inner vessel and outer shell. The second thermal shield is thermally connected to the second heat exchanger and is thermally isolated from the inner vessel, outer shell, first thermal shield, and cold head.

Abstract: An apparatus including a persistent current switch of a superconducting material which is electrically superconducting at a superconducting temperature and electrically resistive at a resistive mode temperature which is greater than the superconducting temperature. The apparatus further includes a first heat exchange element; a convective heat dissipation loop thermally coupling the persistent current switch to the first heat exchange element; a second heat exchange element spaced apart from the first heat exchange element; and a thermally conductive link thermally coupling the persistent current switch to the second heat exchange element. The first heat exchange element is disposed above the persistent current switch. The thermally conductive link may have a greater thermal conductivity at the superconducting temperature than at a second temperature which is greater than the superconducting temperature.

Abstract: An apparatus including an electrically conductive coil which produces a magnetic field when an electrical current passes therethrough; a selectively activated persistent current switch connected across the electrically conductive coil; a cryostat having the electrically conductive coil and the persistent current switch disposed therein; an energy dump; at least one sensor which detects an operating parameter of the apparatus and outputs at least one sensor signal in response thereto; and a magnet controller. The magnet controller receives the sensor signal(s) and in response thereto detects whether an operating fault exists in the apparatus, and when an operating fault is detected, connects the energy dump unit across the electrically conductive coil to transfer energy from the electrically conductive coil to the energy dump unit. The energy dump unit disperses the energy outside of the cryostat.

Abstract: An apparatus includes an electrically conductive coil which produces a magnetic field when an electrical current passes therethrough; a selectively activated persistent current switch connected across the electrically conductive coil; a cryostat having the electrically conductive coil and the persistent current switch disposed therein; an energy dump; at least one sensor which detects an operating parameter of the apparatus and outputs at least one sensor signal in response thereto; and a magnet controller. The magnet controller receives the sensor signal(s) and in response thereto detects whether an operating fault (e.g. a power loss to the compressor of a cryocooler) exists in the apparatus, and when an operating fault is detected, connects the energy dump unit across the electrically conductive coil to transfer energy from the electrically conductive coil to the energy dump unit. The energy dump unit disperses the energy outside of the cryostat.

Abstract: A device is employed for an apparatus including an electrically conductive coil (230) which is disposed within a cryostat (210) and which is configured to produce a magnetic field when an electrical current is passed therethrough. The device dissipates heat from an electrical contact which is disposed within the cryostat and which is configured to supply electrical power to the electrically conductive coil, The device includes: a cooling gas circuit (326) configured to supply a cooling gas to the electrical contact which is disposed within the cryostat and configured to supply electrical power to the electrically conductive coil; and a heat exchanger (308) disposed within the cryostat and configured transfer heat from the electrical contact to the cooling gas to raise the temperature of the cooling gas.

Abstract: A superconducting magnet system, including a cryostat, and a ride-through system for the superconducting magnet system include: one or more gravity-fed cooling tubes configured to have therein a cryogenic fluid; a first heat exchanger configured to transfer heat from the one or more gravity-fed cooling tubes to a cryocooler; a storage device having an input connected to the first heat exchanger and configured to receive and store a boiled-off gas from the first heat exchanger; and a thermal regenerator having an input connected to the output of the storage device.

Abstract: A device is employed for an apparatus including an electrically conductive coil (230) which is disposed within a cryostat (210) and which is configured to produce a magnetic field when an electrical current is passed therethrough. The device dissipates heat from an electrical contact which is disposed within the cryostat and which is configured to supply electrical power to the electrically conductive coil, The device includes: a cooling gas circuit (326) configured to supply a cooling gas to the electrical contact which is disposed within the cryostat and configured to supply electrical power to the electrically conductive coil; and a heat exchanger (308) disposed within the cryostat and configured transfer heat from the electrical contact to the cooling gas to raise the temperature of the cooling gas.

Abstract: An apparatus including a persistent current switch of a superconducting material which is electrically superconducting at a superconducting temperature and electrically resistive at a resistive mode temperature which is greater than the superconducting temperature. The apparatus further includes a first heat exchange element; a convective heat dissipation loop thermally coupling the persistent current switch to the first heat exchange element; a second heat exchange element spaced apart from the first heat exchange element; and a thermally conductive link thermally coupling the persistent current switch to the second heat exchange element. The first heat exchange element is disposed above the persistent current switch. The thermally conductive link may have a greater thermal conductivity at the superconducting temperature than at a second temperature which is greater than the superconducting temperature.

Abstract: An apparatus including an electrically conductive coil which produces a magnetic field when an electrical current passes therethrough; a selectively activated persistent current switch connected across the electrically conductive coil; a cryostat having the electrically conductive coil and the persistent current switch disposed therein; an energy dump; at least one sensor which detects an operating parameter of the apparatus and outputs at least one sensor signal in response thereto; and a magnet controller. The magnet controller receives the sensor signal(s) and in response thereto detects whether an operating fault (e.g. a power loss to the compressor of a cryocooler) exists in the apparatus, and when an operating fault is detected, connects the energy dump unit across the electrically conductive coil to transfer energy from the electrically conductive coil to the energy dump unit. The energy dump unit disperses the energy outside of the cryostat.