Superconductor magnet system, with individual temperature control of axially stacked bulk sub-magnets

Patent metadata

Field	Value
Publication number	US-11798720-B2
Application number	US-202117317330-A
Country	US
Kind code	B2
Filing date	May 11, 2021
Priority date	May 14, 2020
Publication date	Oct 24, 2023
Grant date	Oct 24, 2023

Abstract

A superconductor magnet system (2) includes a cryostat (4), a superconductor bulk magnet (5), and a cryogenic cooling system (12). The bulk magnet (5) has at least N axially stacked bulk sub-magnets (6a-6c), with N≥3. Between each two axially neighboring bulk sub-magnets, an intermediate body (7a-7b) is arranged. The intermediate bodies (7a-7b) are made from a non-metallic thermal insulator material. The cryogenic cooling system (12) is adapted for independently controlling the temperature of each bulk sub-magnet (6a-6c), and has, for each bulk sub-magnet, a temperature sensor (16a-16c) for sensing the temperature of the respective bulk sub-magnet and an adjustment unit (13a-13c) for adjusting a heating power and/or a cooling power at the respective bulk sub-magnet.

First claim

What is claimed is:

1. A superconductor magnet system, comprising:
a cryostat having a room temperature bore,
a superconductor bulk magnet, contained in the cryostat and arranged coaxially with the room temperature bore, and
a cryogenic cooling system adapted for cooling the superconductor bulk magnet, wherein the superconductor bulk magnet comprises:
at least N axially stacked bulk sub-magnets, with N≥3,

wherein the bulk sub-magnets are at least substantially ring shaped and arranged coaxially with the room temperature bore,
a plurality of intermediate bodies, each respectively arranged between two of the axially neighboring bulk sub-magnets,

wherein the intermediate bodies are each at least substantially ring-shaped and arranged coaxially with the room temperature bore,
and wherein the bulk sub-magnets are supported on respective ones of the intermediate bodies,
wherein the intermediate bodies are made from a non-metallic thermal insulator material, having a specific thermal conductivity smaller than a specific thermal conductivity of the material of the bulk sub-magnets,
wherein the cryogenic cooling system is adapted to control respective temperatures of each of the bulk sub-magnets independently of one another,
and wherein the cryogenic cooling system comprises, for each of the bulk sub-magnets:
a respective temperature sensor configured to sense the temperature of the respective bulk sub-magnet, and
a respective adjustment unit configured to adjust a heating power and/or a cooling power at the respective bulk sub-magnet.

2. A superconductor magnet system according to claim 1 , wherein the cryogenic cooling system further comprises:
for each of the bulk sub-magnets:
a respective heater element thermally connected to the respective bulk sub-magnet.

3. A superconductor magnet system according to claim 2 , wherein each of the respective heater elements is an electric heater element.

4. A superconductor magnet system according to claim 2 , wherein the respective heater elements each comprise at least one heater winding wound around a respective one of the bulk sub-magnets.

5. A superconductor magnet system according to claim 4 , wherein the cryogenic cooling system further comprises N metallic rings each respectively annularly framing a respective one of the bulk sub-magnets, and wherein the at least one heater winding is arranged in a circumferential notch of a respective one of the metallic rings.

6. A superconductor magnet system according to claim 1 , wherein the cryogenic cooling system further comprises N metallic rings each respectively annularly framing a respective one of the bulk sub-magnets.

7. A superconductor magnet system according to claim 6 , wherein the metallic rings each extend axially no further than a full axial height of a respective one of the bulk sub-magnets.

8. A superconductor magnet system according to claim 1 , wherein the intermediate bodies are each made of a polyimide material or a glass fiber reinforced plastic material.

9. A superconductor magnet system according to claim 1 , wherein
the cryogenic cooling system further comprises a common cooling stage for the bulk sub-magnets in combination, and
for each of the bulk sub-magnets, a respective thermal connection from the common cooling stage to the respective bulk sub-magnet.

10. A superconductor magnet system according to claim 9 , wherein the respective thermal connections each comprise a thermal impedance.

11. A superconductor magnet system according to claim 9 , wherein
the cryogenic cooling system further comprises a permanently installed first cryocooler comprising a cryocooler cold stage arranged inside the cryostat, wherein the cryocooler cold stage is connected via a thermal impedance or via a thermal switch to the common cooling stage,
and wherein the cryostat further comprises a port and supply lines for an external cooling fluid leading from the port to the common cooling stage and back.

12. A superconductor magnet system according to claim 11 , wherein the first cryocooler is a pulse tube cooler, and wherein the external cooling fluid is supplied by a second cryocooler.

13. A superconductor magnet system according to claim 1 , wherein a radial thickness (RT) of at least one axially inner one of the bulk sub-magnets is equal to or larger than a radial thickness (RT) of axially outer ones of the bulk sub-magnets.

14. A superconductor magnet system according to claim 13 , wherein all of the bulk sub-magnets have mutually identical outer radii (OR).

15. A superconductor charging arrangement, comprising
an electric charger magnet with a charger bore, and
a superconductor magnet system according to claim 1 , arranged at least partially within the charger bore.

16. A method for charging a superconductor magnet system,
wherein the superconductor magnet system comprises:
a cryostat having a room temperature bore,
a superconductor bulk magnet, contained in the cryostat and arranged coaxially with the room temperature bore, and
a cryogenic cooling system adapted for cooling the superconductor bulk magnet,
wherein the superconductor bulk magnet comprises at least N axially stacked bulk sub-magnets, with N≥3, and
wherein the cryogenic cooling system is adapted for independently controlling respective temperatures of each of the bulk sub-magnets,

and wherein the superconductor magnet system is arranged at least partially within a charger bore of an electric charger magnet and is configured with the electric charger magnet according to a specific setup,
the method comprising:
a main field cooling step, wherein a charger current (I ch) of the electric charger magnet is ramped down, causing the superconductor bulk magnet to take over a magnetic flux of the charger magnet and an electric current corresponding to the flux, wherein main currents are induced in the bulk sub-magnets with relative proportions according to a basic distribution scheme for the specific setup of the superconductor magnet system and the electric charger magnet, and wherein none of the bulk sub-magnets is magnetically saturated during the main field cooling step; and
a preparatory charging step, wherein preparatory currents are set in the bulk sub-magnets, with the preparatory currents having relative proportions according to a correction scheme which is different from the basic distribution scheme,

wherein, for setting the preparatory currents according to the correction scheme, temperatures (T bulks) of at least a part of the bulk sub-magnets are selected to differ at least temporarily from each other, and at least temporarily at least a part of the bulk sub-magnets is magnetically saturated during the preparatory charging step,
wherein the main field cooling step takes place after the preparatory charging step, such that the preparatory currents and the main currents add up for the respective bulk sub-magnets, and
wherein a magnetic field profile of the superconductor bulk magnet based on the sum of the preparatory currents and the main currents is more homogenous than a magnetic field profile based on the main currents alone.

17. A method according to claim 16 ,
wherein, during the preparatory charging step, while at least two of the bulk sub-magnets are at different temperatures (T bulks), the charger current (I ch) of the electric charger magnet is changed such that preparatory currents are induced in the bulk sub-magnets, and
wherein during said change of the charger current (I ch) in the preparatory charging step, at least a first part of the bulk

Assignees

• Bruker Switzerland Ag

Inventors

• Hinderer Joerg
• March Stephen Alfred
• Borgnolutti Franck
• Eshchenko Dmitry
• Heiss Stephan
• Bovier Pierre-Alain

Classifications

• H01F6/005 Primary

  Methods and means for increasing the stored energy in superconductive coils by increments (flux pumps) · CPC title

• G01R33/3804

  Additional hardware for cooling or heating of the magnet assembly, for housing a cooled or heated part of the magnet assembly or for temperature control of the magnet assembly · CPC title

• G01R33/3815

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

• H01F6/006

  Supplying energising or de-energising current; Flux pumps · CPC title

• H01F6/04 Primary

  Cooling · CPC title