Cryostat assembly with superconducting magnet coil system with thermal anchoring of the mounting structure

Patent metadata

Field	Value
Publication number	US-11187440-B2
Application number	US-201916526159-A
Country	US
Kind code	B2
Filing date	Jul 30, 2019
Priority date	Jul 31, 2018
Publication date	Nov 30, 2021
Grant date	Nov 30, 2021

Abstract

A cryostat assembly with an outer container for a storage tank with a first cryogenic fluid and a coil tank for a superconducting magnet coil system. The magnet coil system is cooled by a second cryogenic fluid colder than the first cryogenic fluid, the coil tank being mechanically connected to the outer container and/or to radiation shields surrounding the coil tank via a mounting structure. Liquid helium at an operating temperature of approximately 4.2 K is the first cryogenic, fluid and helium at an operating temperature of <3.5 K is the second cryogenic fluid in the coil tank. The mounting structure has mounting elements with thermally conductive contact points thermally coupled to heat sinks having a temperature at or below that of the storage tank, via thermal conductor elements. This ensures long times to quench if malfunctions occur.

First claim

What is claimed is:

1. Cryostat assembly comprising:
an outer container in which a storage tank with a first cryogenic fluid and a coil tank with a superconducting magnet coil system to be cooled are arranged,
wherein the magnet coil system is cooled at least in an operating state by a second cryogenic fluid whose temperature is below that of the first cryogenic fluid, and

a mounting structure mechanically connecting the coil tank to the outer container and/or to at least one radiation shield surrounding the coil tank at least during a transport state of the assembly,
wherein the first cryogenic fluid is liquid helium at an operating temperature of approximately 4.2 K in the storage tank and the second cryogenic fluid is helium at an operating temperature of <3.5 K in the coil tank, and
wherein the mounting structure comprises a plurality of mounting elements each of which has at least one thermally conductive contact point which is thermally coupled, through at least one thermal conductor element, to at least one heat sink, whose temperature is lower than or equal to that of the storage tank.

2. Cryostat assembly according to claim 1 , wherein the second cryogenic fluid is subcooled helium, wherein the pressure of the subcooled helium is above a saturation vapor pressure corresponding to the temperature of the second cryogenic fluid.

3. Cryostat assembly according to claim 1 , wherein the mounting elements are made of a material for which, for a ratio σ/θ of maximum permissible mechanical stress σ, with σ>100 MPa, to an integral θ of a thermal conductivity λ over a temperature range AT between 300 K and 4 K, with θ<300 W/m, the following applies: σ/θ>1/3 (MPa·m)/W.

4. Cryostat assembly according to claim 1 , wherein the mounting elements are made of plastics material.

5. Cryostat assembly according to claim 4 , wherein the mounting elements are made of fiber-reinforced plastics material.

6. Cryostat assembly according to claim 1 , wherein the mounting elements are designed as strut elements, and wherein the thermally conductive contact points are glued onto or into the strut elements or are co-wound in a wound structure of the strut elements.

7. Cryostat assembly according to claim 1 , wherein the mounting elements are each shaped as a loop, each of the loops having at least one thermally conductive contact point.

8. Cryostat assembly according to claim 1 , wherein the mounting elements each have, on an end thereof nearer the coil tank, a thermally conductive contact point which is in mechanical surface contact with the coil tank via a thermally insulating plate on a side thereof facing away from the mounting element.

9. Cryostat assembly according to claim 1 , wherein the thermal conductor element is constructed from a strand or a rod and is made of a material with high thermal conductivity lambda at low temperatures.

10. Cryostat assembly according to claim 9 , wherein the high thermal conductivity at low temperatures is lambda >250 W/(m*K) at a temperature of 4 K, and wherein the material is high-purity copper or high-purity aluminum.

11. Cryostat assembly according to claim 1 , wherein the thermal conductor element comprises a heat pipe or is constructed from a heat pipe.

12. Cryostat assembly according to claim 1 , wherein the thermal conductor element comprises a radiation shield or is constructed from a radiation shield.

13. Cryostat assembly according to claim 12 , wherein the radiation shield comprises or is constructed from a 4.2 K radiation shield.

14. Cryostat assembly according to claim 1 , wherein the at least one heat sink comprises or consists essentially of the storage tank.

15. Cryostat assembly according to claim 14 , wherein the thermal conductor element comprises tube loops with which the contact points and the storage tank are thermally coupled, and wherein the tube loops branch away from the storage tank below a liquid surface of the first cryogenic fluid, lead to the contact points, and then return to a location on the storage tank which is above the liquid surface.

16. Cryostat assembly according to claim 1 , further comprising:
an active cooler comprising subcooling pumps, configured to operate with an uninterruptible power supply in the event of a power failure, wherein the at least one heat sink comprises an exhaust gas of the active cooler, and wherein the active cooler further comprises an exhaust gas line moved past the at least one contact point serially or in parallel with thermal contact.

17. Cryostat assembly according to claim 16 , wherein the active cooler comprises a Joule Thomson refrigerator.

18. Cryostat assembly according to claim 16 , wherein the thermal contact between the storage tank and the exhaust gas line is configured as a movable contact which is connected to an interior of the exhaust gas line and with which contact is alternatingly made or broken.

19. Cryostat assembly according to claim 18 , wherein the thermal contact comprises a mechanically preloaded bellows element which is connected to the interior of the exhaust gas line such that thermal contact is made only above an exhaust gas line pressure of 100 mbar.

20. Cryostat assembly according to claim 1 , further comprising a room temperature bore with a horizontal axis.

Assignees

• Bruker Switzerland Ag

Inventors

• Wikus Patrick
• Bonn Steffen
• Strobel Marco

Classifications

• F17C3/085

  Cryostats · CPC title

• F25B19/005 Primary

  the refrigerant being a liquefied gas · CPC title

• H01F6/04

  Cooling · CPC title

• G01R33/3815

  with superconducting coils, e.g. power supply therefor · CPC title

• G01R33/3802

  Manufacture or installation of magnet assemblies; Additional hardware for transportation or installation of the magnet assembly or for providing mechanical support to components of the magnet assembly · CPC title