JPS61107704A - Method of stabilizing superconductive coil - Google Patents

Abstract

PURPOSE:To obtain a superconductive coil which has a high threshold current value and high reliability by increasing normal conductive transferring dielectric strength forcibly transferring to normal conductivity exciting a superconductive coil partially after manufactured and cooled. CONSTITUTION:The superconductive coil 1 of a superconductive magnet has taps 1A, 1A and middle taps 1B, 1B. After the superconductive coil 1 is manufactured and cooled, exciting voltage is applied to the middle tape 1B, 1B from a D.C. power source 4. A partial coil B between the middle taps is quenched when a current reaches to a specific value and simultaneously at the detection of the quenching, the D.C. power source 4 is cut from the partial coil B and the exciting is stopped. Since the quenched partial coil B is s small part of the coil 1, the stored energy is little, most of the stored energy is consumed by a protection resistance 5 and the temperature of the partial coil cooled by a cooler 3 is not raised. Similarly, the other partial coils A, C are also trained.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for stabilizing a superconducting coil [Prior Art] When a normal conduction transition (quench) occurs in the coil of a superconducting magnet, the coil burns out and liquid He There is a risk of accidents such as ejection, and disturbances in electrical characteristics such as sudden changes in current and magnetic fields may occur.

[Problem that the invention seeks to solve]

For this reason, conventional efforts have been made to improve the cooling capacity of the coil and to improve the fixing structure of the coil wire, but the reliability is insufficient and the critical current value of the coil itself is There was a problem in that the current value had to be set lower than the critical current value.

This invention was made to solve the above-mentioned problems, and aims to obtain a highly reliable superconducting coil with a high critical current value.

[Means to solve the problem]

This invention has a configuration in which training is performed by forcibly quenching each small portion of a superconducting coil body.

[Effect]

In this invention, since quenching is generated in small portions of the superconducting coil body, temperature rise can be prevented and a training effect can be obtained.

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which 1 is a superconducting coil body of a superconducting maknet, and tap I
A, IA, and intermediate taps IB and IB. 3 is a coil cooling unit (cryostat device), 4 is a DC power source for coil excitation, and 5 is a protective resistor.

In this embodiment, after the superconducting coil body 1 has been manufactured and cooled, an excitation voltage is applied between the intermediate taps IB and 18 from the DC power supply 4. When the current flowing through the coil small portion B between the intermediate taps IB and 18 reaches a certain value, it quenches, and at the same time this is detected, the DC power source 4 is disconnected from the coil small portion B to stop excitation. By stopping the excitation, a closed circuit passing through the protective resistor 5 is closed, and most of the energy stored in the small coil portion B is consumed by the protective resistor 5.

Since the quench generation part B at this time is a small part of the coil body 1, the energy stored in the coil body 1 is small, and most of the stored energy is consumed by the protective resistor 5, so it is cooled by the coil cooling part 3. The temperature of the small part of the coil that is inside the coil hardly rises.

In a superconducting coil body, even if a quench occurs, if the temperature of the coil does not rise much from the temperature of the liquid He that cools it, the quench resistance increases and a phenomenon (training) occurs in which the critical current density increases. , the coil small portion B is trained by the excitation or its repetition. After training this coil small section B, repeat the same operation to train other coil small sections A.
, and then the small coil portion C, the entire coil body 1 will be trained, and the critical current value of the coil body 1 will approach the critical current of the superconducting wire itself.

In addition, taps IB, IB, etc. are superconducting magnets ''!''
″”°°゛“75-@EE+*ll[-FhL,-“1
1.1 can be done.

FIG. 2 shows an example of training a persistent current switch circuit of a superconducting coil operating in persistent current mode.

In the figure, 6 is the persistent current switch coil of the persistent current switch circuit, 7 is the heater for the persistent current switch circuit, and 8 is the persistent current switch coil of the persistent current switch circuit.
9 is a power supply for the heater circuit, and 9 is a switch.

In this configuration, for training the persistent current switch coil 6, the switch 9 is turned off and the excitation current Io is supplied from the DC power supply 4 through the ramps IA and IA. As a result, currents ■1 and ■2 flow through the coil body 1 and the switch coil 6, respectively, but if the inductance of the persistent current switch coil 6 is sufficiently smaller than the inductance of the coil body 1, almost no current flows through the coil body 1. I.

=2, the quench can be generated only in this switch equal to 6, and the above-described training can be performed.

〔Effect of the invention〕

As explained above, this invention increases the quench resistance of the superconducting coil body by generating quench in small parts of the superconducting coil body, so that the critical current value of the coil body can be easily adjusted to the critical current value of the coil wire material. This effect can be obtained by increasing the quench resistance of the coil body itself, making it possible to obtain a highly reliable superconducting coil.

[Brief explanation of drawings]

Figure 1 is a circuit diagram for explaining the invention in detail, Figure 2 is a circuit diagram for explaining the invention in detail.
The figure is a circuit diagram for explaining another embodiment of the invention. In the figure, 1--superconducting coil body, 2--small coil section, 3-cooling section, 4--DC power supply for coil excitation 1
．． 5-protective resistor, 6-persistent current switch coil Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (3)

[Claims] (1) A method for stabilizing a superconducting coil, which comprises, after fabricating and cooling a superconducting coil body, energizing small portions of the coil body to force the normal conduction transition to increase the normal conductivity transition proof strength. (2) The superconducting coil body has a tap for small part excitation,
The method for stabilizing a superconducting coil according to claim 1, wherein the tap is used as a voltage detection tap. (3) In the case where a persistent current switch coil is provided, the method for stabilizing a superconducting coil according to claim 1, characterized in that this is excited as a small portion.