Abstract: For shimming a background magnetic field of a magnetic resonance imaging apparatus having an outer vacuum chamber (OVC) bore tube, a shimming arrangement has rails on the OVC bore tube and shim trays are mounted between respective rails.

Abstract: An abstract for a quench valve of a cryostat, in particular for use in a magnetic resonance imaging system, is attachable to the quench valve so as to raise the cracking pressure of the quench valve without changing the operability of the quench valve. Such an accessory device is usable to enable the cryostat, containing a cryogen, to be safely transported by air transportation.

Abstract: In a cryostat, in particular for use in a magnetic resonance imaging (MRI) system, and a method for reducing heat input into such a cryostat, an insert is provided that is adapted to be inserted into an opening of the cryostat. The insert is adapted to provide one or more passageways for a cryogen through the opening by defining at least one space between the outer surface of the insert and at least one part of the inner surface of the opening. This space allows the cryogen to pass over the part of the inner surface of the opening.

Abstract: An arrangement for shimming a background magnetic field of a magnetic resonance imaging apparatus having an outer vacuum chamber (OVC) bore tube (1). Rails (8, 9) are provided on the OVC bore tube and shim trays (4) are mounted between respective rails.

Abstract: A cryogen vessel port arrangement for a magnetic resonance imaging (MRI) system has a port for guiding cryogen into a cryogen vessel. The port has a siphon tube, a siphon cone, which is in flow connection with the siphon tube, and a pipe with an inlet opening and an outlet opening. The inlet opening is configured for connecting it with a coldhead sock and the outlet opening is in flow connection with the port and the siphon cone. The port has a port component that has a flow channel with a first opening configured for connecting it with a service siphon, a second opening in flow connection with the siphon cone, and a third opening in flow connection with the outlet opening of the pipe.

Abstract: An abstract for a quench valve of a cryostat, in particular for use in a magnetic resonance imaging system, is attachable to the quench valve so as to raise the cracking pressure of the quench valve without changing the operability of the quench valve. Such an accessory device is usable to enable the cryostat, containing a cryogen, to be safely transported by air transportation.

Abstract: An over-pressure limiting arrangement for a cryogen vessel includes an access neck providing access into the cryogen vessel, a tubular structure extending through the access neck, a turret outer assembly joined leak-tight to the cryogen vessel and defining an interior volume that is separated from the atmosphere by a protective valve or burst disc, enclosing an upper extremity of the access neck and the tubular structure. An egress path defines a route for cryogen gas to escape from the turret outer assembly, and a pressure-responsive quench valve seals the egress path and opens when a differential pressure between the interior of the turret outer assembly and the interior of the egress path exceeds a predetermined value. An auxiliary burst disc, or a valve, is attached to the tubular structure within the turret outer assembly, with an inner surface thereof exposed to the interior of the tubular structure and an outer surface thereof exposed to the interior of the turret outer assembly.

Abstract: A cryogen vessel port arrangement for a magnetic resonance imaging (MRI) system comprising a port (30) for guiding cryogen into a cryogen vessel is described. The port (30) comprises a siphon tube (32), a siphon cone (33), which is in flow connection with the siphon tube (32), and a pipe (34) with an inlet opening (35) and an outlet opening (36). The inlet opening (35) is configured for connecting it with a coldhead sock and the outlet opening (36) is in flow connection with the port (30) and the siphon cone (33). The port (30) comprises a port component (40) which comprises a flow channel (44) with a first opening (41) configured for connecting it with a service siphon (53, 63), a second opening (42) which is in flow connection with the siphon cone (33), and a third opening (43) which is in flow connection with the outlet opening (36) of the pipe (34).

Abstract: In a cryostat, in particular for use in a magnetic resonance imaging (MRI) system, and a method for reducing heat input into such a cryostat, an insert is provided that is adapted to be inserted into an opening of the cryostat. The insert is adapted to provide one or more passageways for a cryogen through the opening by defining at least one space between the outer surface of the insert and at least one part of the inner surface of the opening. This space allows the cryogen to pass over the part of the inner surface of the opening.

Abstract: An over-pressure limiting arrangement for a cryogen vessel includes an access neck providing access into the cryogen vessel, a tubular structure extending through the access neck, a turret outer assembly joined leak-tight to the cryogen vessel and defining an interior volume that is separated from the atmosphere by a protective valve or burst disc, enclosing an upper extremity of the access neck and the tubular structure. An egress path defines a route for cryogen gas to escape from the turret outer assembly, and a pressure-responsive quench valve seals the egress path and opens when a differential pressure between the interior of the turret outer assembly and the interior of the egress path exceeds a predetermined value. An auxiliary burst disc, or a valve, is attached to the tubular structure within the turret outer assembly, with an inner surface thereof exposed to the interior of the tubular structure and an outer surface thereof exposed to the interior of the turret outer assembly.

Abstract: In an apparatus and a method for detecting deposition of solid frost caused by air ingress into a cryogen vessel, a quartz crystal microbalance, that includes a crystal sensor, is placed within the cryogen vessel, and an actuating circuit actuates resonance of the crystal sensor, and detection equipment detects a change in the resonant characteristics of the crystal sensor caused by frost deposition on the crystal sensor, and signaling equipment indicates the detected change.

Abstract: A superconducting electromagnet comprising coils of superconducting wire bonded to a support structure, and wherein heating elements are provided in thermal contact with the support structure for heating the support structure.

Abstract: A superconducting electromagnet comprising coils of superconducting wire bonded to a support structure, and wherein heating elements are provided in thermal contact with the support structure for heating the support structure.

Abstract: The present invention provides a sensor for detecting the build up of frozen deposits in a cryogen vessel housing a superconducting magnet, comprising a tensioned wire, a source of variable frequency alternating current and a voltage sensor. The tensioned wire is oriented perpendicular to the direction of the stray magnetic field produced by the superconducting magnet. By varying the frequency of the applied current, the resonant frequency of the tensioned wire may be detected as the frequency at which the voltage across the wire is a maximum. Any variation in the frequency or magnitude of the resonant peak may be interpreted as an indication of a frozen deposit hampering the free oscillation of the tensioned wire.

Abstract: The present invention provides a sensor for detecting the build up of frozen deposits in a cryogen vessel housing a superconducting magnet, comprising a tensioned wire, a source of variable frequency alternating current and a voltage sensor. The tensioned wire is oriented perpendicular to the direction of the stray magnetic field produced by the superconducting magnet. By varying the frequency of the applied current, the resonant frequency of the tensioned wire may be detected as the frequency at which the voltage across the wire is a maximum. Any variation in the frequency or magnitude of the resonant peak may be interpreted as an indication of a frozen deposit hampering the free oscillation of the tensioned wire.

Abstract: In an apparatus and a method for detecting deposition of solid frost caused by air ingress into a cryogen vessel, a quartz crystal microbalance, that includes a crystal sensor, is placed within the cryogen vessel, and an actuating circuit actuates resonance of the crystal sensor, and detection equipment detects a change in the resonant characteristics of the crystal sensor caused by frost deposition on the crystal sensor, and signaling equipment indicates the detected change.

Abstract: A super-conducting electro-magnet for use in an MRI system comprising a helium vessel within which magnet windings are positioned, a vacuum chamber within which the helium vessel is contained, at least one thermal shield positioned between the helium vessel and the vacuum chamber in spaced apart relationship, a service turret including a refrigerator thermally coupled to the said at least one shield for cooling purposes, a tube which extends through the turret from the windings to facilitate filling, and conductors which extend through the turret from the windings to facilitate current injection to the windings and to provide a vent for the helium gas.

Abstract: A superconducting electromagnet comprising coils of superconducting wire bonded to a support structure, and wherein heating elements are provided in thermal contact with the support structure for heating the support structure.