Monitoring device for cryogenic device

Patent metadata

Field	Value
Publication number	US-11114230-B2
Application number	US-201916965793-A
Country	US
Kind code	B2
Filing date	Jan 30, 2019
Priority date	Jan 30, 2018
Publication date	Sep 7, 2021
Grant date	Sep 7, 2021

Abstract

A monitoring device for use in a cryogenic system. The monitoring device comprises first and second conducting elements and a current detector. The first conducting element comprises high temperature superconducting, HTS, material and is configured for connection to a current source and insertion into the cryogenic system. The second conducting element comprises HTS material and is connected in parallel to the first conducting element by first and second joints. The current detector is configured to detect a current in the second conducting element. When the HTS material in each of the first and second conducting elements is in a superconducting state, the resistance, R T , of the first conducting element between the first and second joints, is less than the sum, R B , of the resistance of the second conducting element between the first and second joints and the resistances of the first and second joints.

First claim

The invention claimed is:

1. A monitoring device for use in a superconducting or cryogenic system, the monitoring device comprising:
a first conducting element comprising a high temperature superconducting, HTS, material and configured for connection to a current source and insertion into the superconducting or cryogenic system;
a second conducting element comprising a HTS material and connected in parallel to the first conducting element by first and second joints; and
a current detector configured to detect a current in the second conducting element;
wherein, when the HTS material in each of the first and second conducting elements is in a superconducting state, a resistance, R T , of the first conducting element between the first and second joints, is less than a sum, R B , of the resistance of the second conducting element between the first and second joints and the resistances of the first and second joints, R T <R B .

2. The monitoring device according to claim 1 , wherein the first and/or second conducting elements are arranged as one or more pairs of parallel elements, with the elements of each pair being adjacent to each other and configured to carry a current in opposite directions.

3. The monitoring device according to claim 1 , wherein the current detector comprises one or more of:
a conductive loop around the second conducting element;
a magnetic field detector;
a Hall probe; and
a strain gauge coupled to two sections of the second conducting element which carry the current in different directions.

4. The monitoring device according to claim 1 , and further comprising a current source configured to provide a current to the first conducting element.

5. The monitoring device according to claim 4 , wherein the current source is modulated to as to provide a periodic time-varying current.

6. The monitoring device according to claim 5 , wherein the current detector comprises a phase sensitive detector.

7. The monitoring device according to claim 5 , wherein the current detector is configured to measure a duty cycle of the current in the second conducting element.

8. The monitoring device according to claim 4 , wherein the current source is configured to provide a peak current of at least 80% of the critical current of a part of the HTS material of the first conducting element during normal operation of the superconducting or cryogenic system.

9. The monitoring device according to claim 1 , wherein the first and/or second conducting element comprise a HTS tape having an HTS layer.

10. The monitoring device according to claim 9 , wherein a width of the HTS layer varies within section of the first conducting element between the joints.

11. The monitoring device according to claim 9 , wherein the HTS layer is divided into a plurality of strips connected in series.

12. The monitoring device according to claim 1 , wherein the current detector is enclosed in a magnetic shield.

13. The monitoring device according to claim 12 , wherein the magnetic shield comprises a bulk superconductor.

14. The monitoring device according to claim 13 , further comprising a plurality of additional conducting elements comprising HTS material and connected in parallel to the first conducting element.

15. The monitoring device according to claim 1 , further comprising a third conducting element comprising a HTS material and connected in parallel to the first conducting element by third and fourth joints, wherein, when the HTS material in each of the first, second and third conducting elements is in a superconducting state, the resistance, R T , of the first conducting element between the first and second joints, is less than a sum, R B2 , of the resistance of the third conducting element between the third and fourth joints and a resistances of the third and fourth joints, and the sum, R B2 , of the resistance of the third conducting element between the third and fourth joints and the resistances of the third and fourth joints is less than the sum, R B , of the resistance of the second conducting element between the first and second joints and the resistances of the first and second joints R T <R B2 <R B , and wherein a peak critical current of the HTS material of the third conducting element is less than a peak critical current of the HTS material of the first conducting element, and wherein the current detector is additionally configured to detect a current in the third conducting element.

16. The monitoring device according to claim 1 , wherein the second conducting element comprises a variable resistance.

17. The monitoring device according to claim 16 , wherein the variable resistance is one of:
a potentiometer;
a system for controllably causing the HTS material in the second conducting element to become normal; and
a joint or section of normal conducting material having a temperature-dependent resistance and a device for controlling the temperature thereof.

18. The monitoring system comprising a plurality of monitoring devices according to claim 1 and a controller configured to monitor currents detected by each monitoring device.

19. The monitoring system according to claim 18 , wherein the controller is configured to identify reductions in critical currents of the first conducting elements of the monitoring devices on the basis of currents detected in the second conducting elements of the respective monitoring devices.

20. The monitoring system according to claim 19 , wherein the controller is configured to identify a cause of the reduction in critical current on the basis of the pattern of reductions in critical currents identified for the monitoring devices.

21. The superconducting magnet comprising an HTS field coil and a monitoring device according to claim 18 , wherein each first conducting element is located adjacent to the HTS field coil.

22. The monitoring system according to claim 18 , wherein the controller is configured to identify conditions likely to result in a quench on the basis of a rapid reduction in critical currents identified for one or more of the monitoring devices.

23. The quench protection system for use in a superconducting magnet, the quench protection system comprising a monitoring system according to claim 22 , and a system for dumping energy from a superconducting magnet, wherein the controller of the monitoring system is configured to trigger the system for dumping energy from the superconducting magnet in dependence upon identification of conditions likely to cause a quench.

24. The monitoring system according to claim 18 , wherein the monitoring devices are arranged in one or more pairs, each pair comprising a first and second monitoring device, wherein:
the first and second conducting elements of the first monitoring device are arranged adjacent to the respective first and second conducting elements of the second monitoring device; and
the first and second monitoring devices are arranged such that currents in the first conducting element of the each monitoring device flow in the same direction, and currents in the second conducting element of the each monitoring device flow in opposite directions.

25. The monitoring system according to claim 18 , wherein:
the monitoring devices are arranged in one or more sets, each set comprising monitoring devices having first conducting elements with differing patterns of measurement regions and non-measurement regions along the first conducting element;

Assignees

• Tokamak Energy Ltd

Inventors

• Brittles Greg
• Slade Robert
• Kruip Marcel
• Van Nugteren Bas

Classifications

• H02H7/001

  for superconducting apparatus, e.g. coils, lines, machines · CPC title

• G01R19/0092

  Measuring current only · CPC title

• H01F41/048

  Superconductive coils · CPC title

• H01F6/02 Primary

  Quenching; Protection arrangements during quenching {(protection circuits H02H7/001)} · CPC title

• G01R19/12

  Measuring rate of change · CPC title