A cryogen tank in thermal and mechanical attachment with the equipment to be cooled. Direct thermal conduction between the cryogen and the equipment provides the required cooling. The tank is preferably arranged so as to lie within an existing profile of the cooled equipment, and to be relatively sm
A cryogen tank in thermal and mechanical attachment with the equipment to be cooled. Direct thermal conduction between the cryogen and the equipment provides the required cooling. The tank is preferably arranged so as to lie within an existing profile of the cooled equipment, and to be relatively small as compared to known cryogen tanks.
대표청구항▼
The invention claimed is: 1. A substantially cylindrical former for a solenoidal magnet, in combination with a cryogen tank for containing a cryogen for cooling the former, wherein: the cryogen tank comprises a substantially toroidal or cylindrical enclosure that is enclosed by outer surfaces there
The invention claimed is: 1. A substantially cylindrical former for a solenoidal magnet, in combination with a cryogen tank for containing a cryogen for cooling the former, wherein: the cryogen tank comprises a substantially toroidal or cylindrical enclosure that is enclosed by outer surfaces thereof and is coaxial with the former: the former is situated outside of said enclosure: an outer surface of the cryogen tank is in thermal contact with and mechanically attached to the former; the former comprises an inner part having a first diameter and at least one outer part having a second diameter greater than the first diameter; and the cryogen tank is substantially housed within a substantially toroidal volume that is coaxial with the former, and has an outer diameter equal to the second diameter, and an inner diameter equal to the first diameter. 2. The combination according to claim 1, wherein: the inner and outer parts of the former are mechanically linked by a plurality of webs that are shaped to accommodate at least part of the cross-section of the cryogen tank, and the outer surface of the cryogen tank is thermally linked and mechanically attached to the webs. 3. The combination according to claim 1, wherein inner and outer parts of the former are mechanically and thermally linked by the cryogen tank. 4. The combination according to claim 3, wherein the cryogen tank is located in close thermal contact with an outer shield coil, a drive coil and a field shaping coil. 5. The combination according to claim 1, further comprising a plurality of coils mounted on the former, said plurality of coils forming a solenoidal magnet. 6. The combination according to claim 1, wherein the cryogen tank has a substantially circular cross-section. 7. The combination according to claim 1, further comprising a recondensing refrigerator for maintaining a cryogen level within the cryogen tank. 8. The combination according to claim 1, further comprising cryogen tanks symmetrically placed in locations near the ends of the former. 9. The combination according to claim 1, wherein the cryogen tank contains heat transfer formations. 10. The combination according to claim 1, wherein the cryogen tank contains an open celled thermally conductive material. 11. The combination according to claim 1, wherein the or each cryogen tank is formed of suitably shaped sheets of thermally conductive material. 12. The combination according to claim 1, wherein the or each cryogen tank is formed of one or more suitably shaped extrusions. 13. The combination according to claim 10, wherein the outer part of the former is formed as part of an extrusion. 14. The combination according to claim 1, housed within an outer cryogen tank. 15. An MRI system comprising a solenoidal magnet in combination with a cryogen tank according to claim 1. 16. A method for cooling a solenoidal magnet, comprising the steps of: providing a plurality of coils mounted on a substantially cylindrical former to form the solenoidal magnet, the former comprising an inner part having first diameter and at least one outer part having a second diameter greater than the first diameter; providing a cryogen tank that comprises an enclosure that is enclosed by outer surfaces thereof, with said former being situated outside said enclosure; wherein, an outer surface of said enclosure is in thermal contact with and mechanical attachment to the former; said cryogen tank is i) substantially toroidal or cylindrical in shape, ii) coaxial with the former, and iii) housed substantially within a substantially toroidal volume that is coaxial with the former; said cryogen tank has an outer diameter equal to the second diameter, and an inner diameter equal to the first diameter; and the cryogen tank is filled with a cryogen, thereby cooling the solenoidal magnet by conduction of heat from the coils, through the material of the former and the outer surface of the tank, to the cryogen. 17. A method according to claim 16, wherein the cryogen tank is filled with a working cryogen to cool the solenoidal magnet to an operating temperature. 18. A method according to claim 16, wherein the cryogen tank is first filled with a quantity sacrificial cryogen, which completely boils away to cool the solenoidal magnet to a first temperature, higher than an operating temperature; and the cryogen tank is then filled with a working cryogen to cool the solenoidal magnet to an operating temperature. 19. A method according to claim 16, wherein the cryogen tank is filled with a sacrificial cryogen, thereby to cool the solenoidal magnet to a first temperature, higher than an operating temperature; and the solenoidal magnet is further cooled by immersion in a working cryogen to cool the solenoidal magnet to the operating temperature. 20. The method according to claim 19, wherein the cryogen tank is at least substantially empty of sacrificial cryogen when the solenoidal magnet is immersed in working cryogen. 21. The method according to claim 16, wherein: the inner and outer parts of the former are mechanically linked by a number of webs; said webs are shaped to accommodate at least part of the cross-section of the tank; and said cryogen tank is attached by its outer surface in thermal contact with and mechanical attachment to the webs. 22. The method according to claim 16, wherein the inner and outer parts of the former are mechanically and thermally linked by outer surfaces of the cryogen tank. 23. The method according to claim 16, wherein the cryogen tank is located in close thermal contact with an outer shield coil, a drive coil and a field shaping coil. 24. The method according to claim 16, further comprising the step of recondensing cryogen boiled off from the cryogen tank, thereby to maintain a cryogen level within the cryogen tank. 25. The method according to claim 16, wherein the cryogen tank is formed of suitably shaped sheets of thermally conductive material. 26. The method according to claim 16, wherein the cryogen tank is formed of one or more suitably shaped extrusions. 27. The method according to claim 26, wherein the outer part of the former is formed as part of an extrusion. 28. Apparatus for cooling coils of a solenoidal magnet, comprising: a former on which said coils are wound, said former comprising an inner part having a first diameter, and an outer part that is coaxial with said first part and has a second diameter, greater than the first diameter; a supporting structure connected between said inner part and said outer part for maintaining a fixed spatial relationship between said parts; and a contact cryogen tank comprising a separate enclosure which is enclosed by outer surfaces thereof, is in thermal contact with said former, and is mounted within a substantially toroidal volume between said first and second diameters. 29. The apparatus according to claim 28, wherein said contact cryogen tank is supported on and in thermal contact with said supporting structure. 30. The apparatus according to claim 28, wherein said contact cryogen tank forms at least a part of said supporting structure.
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이 특허에 인용된 특허 (6)
Mulder, Gerardus Bernardus Jozef, Cooling of a MRI system.
Laskaris, Evangelos Trifon; Alexander, James Pellegrino; Thompson, Paul St. Mark Shadforth; Zhang, Tao; Chen, William; Jiang, Longzhi, Cooling system and method for cooling superconducting magnet devices.
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