Rapid dump of partially insulated superconducting magnet

Patent metadata

Field	Value
Publication number	US-2022016442-A1
Application number	US-201917296167-A
Country	US
Kind code	A1
Filing date	Nov 21, 2019
Priority date	Nov 22, 2018
Publication date	Jan 20, 2022
Grant date	—

Abstract

An HTS magnet system comprising an HTS field coil and a power supply. The HTS field coil comprises a plurality of turns comprising HTS material and a metallic stabiliser; and an electrically conductive layer separating the turns, such that current can be shared between turns via the conductive layer. The power supply is configured to: during ramp-up of the HTS field coil, provide a first current to the HTS field coil; and during ramp-down of the HTS field coil, provide a second current to the HTS field coil opposite in direction to the first current.

First claim

1 . A high temperature superconductor, HTS, magnet system comprising an HTS field coil and a power supply, wherein:
the HTS field coil comprises:
a plurality of turns comprising HTS material and a metallic stabiliser;
an electrically conductive layer separating the turns, such that current can be shared between turns via the conductive layer;
the power supply is configured to:
during ramp-up of the HTS field coil, to provide a first current to the HTS field coil
during ramp-down of the HTS field coil, to provide a second current to the HTS field coil opposite in direction to the first current.

2 . An HTS magnet system according to claim 1 , and comprising:
a quench detection system configured to detect a quench in the HTS material and/or to detect conditions likely to cause a quench in the HTS material; wherein the power supply is configured to ramp down the HTS field coil in response to detection of a quench or conditions likely to cause a quench by the quench detection system.

3 . An HTS magnet system according to claim 1 , wherein the second current is a DC current.

4 . An HTS magnet system according to claim 1 , wherein the second current is a combination of a DC and an AC current, such that the current varies sinusoidally with an average value opposite in sign to the first current, and a period less than a time constant of the HTS field coil.

5 . An HTS magnet system according to claim 1 , wherein the power supply comprises a four quadrant power supply unit. PSU.

6 . An HTS magnet system according to claim 1 , wherein the power supply comprises a single quadrant power supply unit, PSU, and a capacitor, wherein the single quadrant PSU is configured to provide the first current and the capacitor is configured to provide the second current.

7 . An HTS magnet system according to claim 1 , wherein the power supply is configured to provide the second current until one of:
detection of a quench in a predefined portion of the HTS field coil; detection of a specified temperature in a predefined portion of the HTS field coil; detection that a magnetic field generated by the magnet has decreased below a threshold value; and detection that a current in HTS material of the HTS field coil has decreased below a threshold value.

8 . An HTS magnet system according to any preceding claim 1 , wherein the power supply comprises a feedback system configured to control current provided to the magnet in dependence upon one or more of:
current in the HTS material of the magnet; temperature of the HTS field coil; and
magnetic field of the HTS field coil.

9 . A high temperature superconductor, HTS, magnet system comprising an HTS field coil and a power supply, wherein:
the HTS field coil comprises:
a plurality of turns comprising HTS material and a metallic stabiliser;
an electrically conductive layer separating the turns, such that current can be shared between turns via the conductive layer;
the power supply is configured to:
during ramp-up of the HTS field coil, to provide a first current to the HTS field coil
during ramp-down of the HTS field coil, to provide a second current to the HTS field coil which is in the same direction as the first current and less than a current in the HTS material of the field coil.

10 . An HTS magnet system according to claim 9 , wherein the second current is a combination of a DC and an AC current, such that the current varies sinusoidally with an average value greater than zero and less than the first current, and a period less than a time constant of the HTS field coil.

11 . A high temperature superconductor, HTS, magnet system comprising an HTS field coil and a power supply, wherein:
the HTS field coil comprises:
a plurality of turns comprising HTS material and a metallic stabiliser;
an electrically conductive layer separating the turns, such that current can be shared between turns via the conductive layer;
the power supply is configured to:
provide DC current to the HTS field coil; and
provide AC current to the HTS field coil in addition to the DC current in order to heat the field coil, the AC current having a period less than a time constant of the field coil and a magnitude less than the DC current.

12 . A tokamak comprising a magnet system according to claim 1 , wherein an HTS field coil of the magnet system is one of a toroidal field coil or poloidal field coil of the tokamak.

13 . A proton beam therapy, PBT, device comprising a magnet system according to claim 1 , wherein an HTS field coil of the magnet system is one of:
a field coil of an accelerator of the PBT device; a dipole or quadrupole magnet of a proton beam steering system of the PBT device.

14 . A method of ramping down a high temperature superconductor, HTS, field coil, wherein the HTS field coil comprises a plurality of turns comprising HTS material and a metallic stabiliser and an electrically conductive layer separating the turns, such that current can be shared between turns via the conductive layer, the method comprising applying a second current to the HTS field coil in opposition to a first current flowing in the HTS material.

15 . A method according to claim 14 , wherein the second current is applied in response to detection of a quench or conditions likely to cause a quench in the HTS field coil.

16 . An method according to claim 14 , wherein the second current is applied until one of:
detection of a quench in a predefined portion of the HTS field coil; detection of a specified temperature in a predefined portion of the HTS field coil; detection that a magnetic field generated by the magnet has decreased below a threshold value; and detection that a current in HTS material of the HTS field coil has decreased below a threshold value.

17 . A method according to claim 14 , wherein the second current is a combination of a DC and an AC current, such that the current varies sinusoidally with an average value opposite in sign to the first current, and a period less than a time constant of the HTS field coil.

18 . A method of ramping down a high temperature superconductor, HTS, field coil, wherein the HTS field coil comprises a plurality of turns comprising HTS material and a metallic stabiliser and an electrically conductive layer separating the turns, such that current can be shared between turns via the conductive layer, the method comprising applying a second current to the HTS field coil which is less than a first current flowing in the HTS material.

19 . A method according to claim 18 , wherein the second current is a combination of a DC and an AC current, such that the current varies sinusoidally with an average value greater than zero and less than the first current, and a period less than a time constant of the HTS field coil.

20 . A method of heating a high temperature superconductor, HTS, field coil, wherein the HTS field coil comprises a plurality of turns comprising HTS material and a metallic stabiliser and an electrically conductive layer separating the turns, such that current can be shared between turns via the conductive layer, the method comprising applying a combined DC and AC current to the HTS field coil.

21 . A method according to claim 20 , wherein the DC current is equal to a current in the HTS material of the HTS field coil.

22 - 35 . (canceled)

Assignees

• Tokamak Energy Ltd

Inventors

• Slade Robert
• Van Nugteren Bas

Classifications

• Y02E30/10

  Nuclear fusion reactors · CPC title

• A61N2005/1087

  Ions; Protons · CPC title

• G21B1/057

  Tokamaks · CPC title

• A61N5/1077 Primary

  Beam delivery systems · CPC title

• H01F6/006 Primary

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