Magnetic Field Control

a magnetic field and control technology, applied in the manufacture/treatment of superconducting magnets/coils, dc source parallel operation, superconducting device manufacturing/treatment, etc., can solve the problem of affecting the reaction time of the power supply, the magnetic field cannot be controlled to a few ppm accuracy, and the relative low level of accuracy and stability

Inactive Publication Date: 2015-07-02
HTS 110 LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention is about a stable and reliable way to generate a strong magnetic field using a superconducting material. The method includes using a main current to generate the field, measuring the magnetic field and then using an auxiliary current to fine-tune the magnetic field to match a predetermined value. This allows for a more accurate and stable magnetic field.

Problems solved by technology

A disadvantage of this method is a relatively low level of accuracy and stability since the resolution of the main current PSU, which has an output current of typically 50-1000 A, is of the order of a few PPM and so provides a current output resolution of order 1 mA and so the magnetic field cannot be controlled to an accuracy of better than a few PPM.
Another disadvantage is that the reaction time of the power supply is damped due to the stabilising circuitry associated with the DC current transducers.
This tends to dampen the change of the magnetic field and lower the magnetic field drift rate.
However this method merely slows the rate of magnetic field drift without actually correcting it.
A limitation is that the shim coil has a reduced response due to a low number of turns and therefore does not offer a sufficient amount of correction.

Method used

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Embodiment Construction

[0030]The invention relates to an assembly for generating a stable superconducting magnetic field.

[0031]Referring to FIG. 1, the assembly comprises a main magnetic power supply unit 1 across the input terminals of a coil assembly 2. The main magnetic power supply unit 1 aims to provide a main current, typically in the range of 50-1000 Amps to the magnet coil 2. The stability of this main current is typically in a range of a few PPM per hour (parts per million). It is to be understood that magnet coil 2 is subject to a number of factors which would cause the magnetic field generated to drift irrespective of the stability of the main input current. Some of these factors include flux redistribution within the superconductor and thermal drift due to small changes in the dimensions of the magnet created by environmental temperature changes. As a result, the magnetic field stability can be no better than the stability of the output current from the main power supply unit 1. In long term o...

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Abstract

An assembly for generating a superconducting magnetic field with high stability comprises a main power supply unit arranged to provide a main current to generate a superconducting magnetic field, a magnetic field measurement device for measuring the generated magnetic field, and an auxiliary power supply unit arranged to output an auxiliary current based on the measured magnetic field.

Description

FIELD OF THE INVENTION[0001]The invention relates to a superconducting circuit arranged to produce a stable and accurate superconducting magnetic field. The invention also relates to a method for generating a stable superconducting magnetic field and a method for stabilising a superconducting magnetic field.BACKGROUND TO THE INVENTION[0002]Due to thermal drift of the magnet or power supply, or flux creep in the superconducting main magnet coil, a magnetic field from a superconducting circuit may fluctuate or drift.[0003]One approach to minimise deviations and improve the stability of the field generated is to include a field measurement device to measure the magnetic field value and feedback an error signal to the power supply (PSU). A disadvantage of this method is a relatively low level of accuracy and stability since the resolution of the main current PSU, which has an output current of typically 50-1000 A, is of the order of a few PPM and so provides a current output resolution ...

Claims

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Application Information

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IPC IPC(8): H01F6/00H01F6/06G01R33/07G01R33/035G01R33/24G01R33/09
CPCH01F6/008G01R33/24H01F6/06G01R33/07G01R33/0354G01R33/093G01R33/0041
InventorMALLETT, MICHAEL JOHN DISNEY
OwnerHTS 110 LTD