JP7110035B2 - Superconducting magnet device - Google Patents

Description

An embodiment of the present invention is provided with a persistent current switch, and protects the persistent current switch when the persistent current switch is forcibly quenched even when an abnormality occurs in the current supply line that supplies the current from the excitation power supply to the superconducting coil. The present invention relates to a superconducting magnet device.

A superconducting wire has ranges of current density, temperature, and magnetic field that maintain the superconducting state, that is, so-called critical current density, critical temperature, and critical magnetic field. Therefore, even if the electrical resistance is almost zero, the current cannot flow infinitely, and if any critical value is exceeded, a transition phenomenon to the normal conducting state, that is, a quench occurs. Joule heating in the normal-conducting transition region due to such a quench causes instantaneous thermal runaway of the superconducting coil, and in the worst case, it may lead to burnout. Therefore, a quench protection technique is essential.

As a conventional technique for quench protection of a superconducting coil, for example, there is a configuration in which an exciting power supply is connected to the superconducting coil, and a protective resistor placed in a room temperature region is connected in parallel to this exciting power supply. In this configuration, the coil voltage and temperature rise generated by the transition of the superconducting coil to the normal conducting state are detected, and this is used as a trigger to urgently cut off the excitation power supply. After this emergency shutoff, the superconducting coil and the protection resistor form a closed circuit, so the magnetically stored energy (magnetic energy) of the superconducting coil is consumed by the Joule heating of the protection resistor, and the superconducting coil is demagnetized to avoid thermal runaway. becomes possible.

By the way, in a superconducting magnet apparatus such as a nuclear magnetic resonance spectrometer (NMR) or a magnetic resonance imaging apparatus (MRI), high temporal stability is required for the magnetic field generated during normal operation. For this reason, in the superconducting magnet device 100 described in Patent Document 1, as shown in FIG. , and a persistent current switch 104 is electrically connected in parallel to the superconducting coil 101 . Among them, the superconducting coil 101 and the persistent current switch 104 are arranged inside a radiation shield 106 provided inside a vacuum vessel 105 .

The persistent current switch 104 is generally composed of a superconducting wire, and in a state cooled below the superconducting transition temperature Tc, the current flows through a closed loop with zero electric resistance in principle, including the superconducting coil 101 and the persistent current switch 104, as indicated by the arrow. It flows like α. Therefore, superconducting coil 101 can generate a very stable magnetic field without current attenuation. This persistent current switch 104 is turned on and off using temperature changes.

That is, during excitation and demagnetization, the permanent current switch 104 is heated above the superconducting transition temperature Tc by using the heater 107 or the like in order to prevent the current from being shunted to the persistent current switch 104 and supply the current to the superconducting coil 101 from the excitation power source 102 . Heat to make it high resistance (off resistance). Further, when shifting to normal operation (persistent current mode operation) using the closed loop described above after excitation, the heater 107 is turned off to cool the persistent current switch 104, and the persistent current switch 104 is cooled to the superconducting transition temperature Tc. The superconducting state can be restored as follows.

Even when the persistent current switch 104 is used, when the excitation power source 102 is urgently cut off for quench protection of the superconducting coil 101 as described above, the room temperature region outside the vacuum vessel 105 or the Thus, the magnetic energy of the superconducting coil 101 is consumed by the protective resistor 103 arranged near the room temperature region in the vacuum vessel 105 . For this purpose, the persistent current switch 104 is forcibly heated to the superconducting transition temperature Tc or higher as in the case of excitation and demagnetization, and the persistent current switch 104 is forcibly quenched to a normal conducting state having a resistance higher than that of the protective resistor 103. need to let

By the way, as the superconducting wire constituting the superconducting coil 101 and the persistent current switch 104, a high-temperature superconducting wire having a high critical current density even in a high temperature range of 20K to 50K may be used. In the superconducting magnet device 100 (that is, the high-temperature superconducting magnet device) including the superconducting coil 101 and the persistent current switch 104, the current circulates in the direction of the arrow α in the closed loop including the persistent current switch 104. After excitation, there is an advantage that the operation of the superconducting magnet device 100 can be continued even if a part of the current supply line 108 in the cryogenic region inside the vacuum vessel 105 is broken (indicated by a broken point 109) or other abnormality occurs.

JP-A-2008-41966 "Development of Persistent-Current Mode HTS Coil for the RT-1 Plasma Device" IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTION, VOL.16, NO.2, 910-913, JUNE 2006

However, if an abnormality occurs in the current supply line 108 in the cryogenic region within the vacuum vessel 105, the magnetic energy of the superconducting coil 101 is consumed using the protection resistor 103 in the room temperature region for quench protection of the superconducting coil 101. Can not do it. Therefore, the magnetic energy of superconducting coil 101 has to be consumed over a long period of time by minute resistance components such as the connecting portions inside superconducting coil 101 .

On the other hand, a method of forcibly quenching persistent current switch 104 to the superconducting transition temperature Tc or higher and consuming the magnetic energy of superconducting coil 101 with the off-resistance generated in persistent current switch 104 is also conceivable. However, since the persistent current switch 104 has a small heat capacity, if most of the large magnetic energy of the superconducting coil 101 is consumed by the persistent current switch 104, the temperature of the persistent current switch 104 will rise excessively, resulting in thermal runaway and burning. There is a problem.

The embodiments of the present invention have been made in consideration of the above circumstances, and are designed to force a permanent current switch to demagnetize the superconducting coil when an abnormality occurs in the current supply line that supplies the current to the superconducting coil. It is an object of the present invention to provide a superconducting magnet device capable of preventing thermal runaway due to excessive temperature rise of the persistent current switch when quenched, and demagnetizing the superconducting coil in a short period of time.

A superconducting magnet device according to an embodiment of the present invention includes a vacuum vessel, a radiation shield provided in the vacuum vessel, a superconducting coil provided in the radiation shield, and an excitation power supply that supplies current to the superconducting coil. and a persistent current switch electrically connected in parallel to the superconducting coil and provided within the radiation shield,
a normal-conducting resistor electrically connected in parallel to the persistent current switch and thermally connected to the radiation shield ; A resistance value of the normal-conducting resistor is set larger than a resistance value of the protection resistor and smaller than an off-resistance of the persistent current switch .
A superconducting magnet device according to an embodiment of the present invention includes a vacuum vessel, a radiation shield provided in the vacuum vessel, a superconducting coil provided in the radiation shield, and an excitation coil for supplying current to the superconducting coil. A superconducting magnet apparatus comprising a power supply and a persistent current switch electrically connected in parallel to the superconducting coil and provided within the radiation shield, wherein the persistent current switch is electrically connected in parallel to the It has a normal conducting resistor thermally connected to a radiation shield, and the normal conducting resistor is provided with temperature control means capable of controlling the temperature of the normal conducting resistor. .
Furthermore, the superconducting magnet device according to the embodiment of the present invention includes a vacuum vessel, a radiation shield provided in the vacuum vessel, a superconducting coil provided in the radiation shield, and an excitation coil for supplying current to the superconducting coil. A superconducting magnet apparatus comprising a power supply and a persistent current switch electrically connected in parallel to the superconducting coil and provided within the radiation shield, wherein the persistent current switch is electrically connected in parallel to the a normal-conducting resistor thermally connected to a radiation shield, wherein a thermal connection portion between the normal-conducting resistor and the radiation shield has a thermal resistance between the normal-conducting resistor and the radiation shield; is provided with a thermal switch capable of adjusting the

According to the embodiment of the present invention, when an abnormality occurs in a current supply line that supplies a current to a superconducting coil and the persistent current switch is forcibly quenched in order to demagnetize the superconducting coil, the excessive current switch The superconducting coil can be demagnetized in a short period of time while preventing thermal runaway due to an excessive temperature rise.

1 is an electric circuit diagram showing a superconducting magnet device according to a first embodiment; FIG. The electric circuit diagram which shows the superconducting-magnet apparatus which concerns on 2nd Embodiment. The electric circuit diagram which shows the superconducting-magnet apparatus which concerns on 3rd Embodiment. The electric circuit diagram which shows the superconducting-magnet apparatus which concerns on 4th Embodiment. The electric circuit diagram which shows the superconducting-magnet apparatus which concerns on 5th Embodiment. FIG. 6 is a side sectional view showing the normal conducting resistor of FIG. 5; An electric circuit diagram showing a conventional superconducting magnet device.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on drawing.
[A] First embodiment (Fig. 1)
FIG. 1 is an electric circuit diagram showing a superconducting magnet device according to a first embodiment. A high-temperature superconducting magnet device 10 as a superconducting magnet device shown in FIG. A protective resistor 13 is electrically connected in parallel to the excitation power supply 12, a persistent current switch 14 is electrically connected in parallel to the high temperature superconducting coil 11, and a normal conducting resistor 15 is provided. configured as

Since the high-temperature superconducting coil 11 and the persistent current switch 14 are used at extremely low temperatures, they are housed in a vacuum container 16 that is vacuum-insulated from the outside air. It is located within an enclosed cryogenic region M. As a result, the high-temperature superconducting coil 11 and the persistent current switch 14 are cooled to about 20K to 50K by a refrigerator (not shown).

The radiation shield 17 reduces heat input due to radiation from the room temperature region N within the vacuum vessel 16 . The radiation shield 17 is preferably made of a metal with good heat conductivity such as aluminum or copper, and more preferably a metal with good heat conductivity and light weight, such as aluminum.

The high-temperature superconducting coil 11 is a superconducting coil made of a high-temperature superconducting wire. Examples of high-temperature superconducting wires include Bi ₂ Sr ₂ Ca ₂ Cu ₃ O ₁₀ wires and REBaCuO ₇ wires. The high-temperature superconducting coil 11 using this high-temperature superconducting wire has a high critical current density even at a high temperature of about 20 K to 50 K compared to a superconducting coil using a low-temperature superconducting wire such as NbTi. It is possible to reduce the size of the coil.

Also, the high-temperature superconducting coil 11 is equivalently represented by an inductance 11L and a resistance component 11R. As the resistance component 11R, the high-temperature superconducting wire of the high-temperature superconducting coil 11 is flux flow resistance generated in the process of transitioning from the superconducting state to the normal conducting state near the superconducting transition temperature Tc, the connection resistance between the high-temperature superconducting wires, and the high-temperature superconducting coil 11. There is a connection resistance of each coil when it consists of a plurality of coils.

The protective resistor 13 is electrically connected in parallel to the excitation power supply 12 and placed in the room temperature region N within the vacuum vessel 16 . This protective resistor 13 consumes the magnetic energy accumulated in the high-temperature superconducting coil 11 by converting it into Joule heat when the excitation power supply 12 is suddenly cut off to protect the high-temperature superconducting coil 11 from quenching.

The persistent current switch 14 is arranged in the cryogenic region M surrounded by the radiation shield 17 inside the vacuum vessel 16 together with the high-temperature superconducting coil 11 as described above, and is electrically connected in parallel with the high-temperature superconducting coil 11. be done. The superconducting wire constituting the persistent current switch 14 is designed to have the same operating temperature as the high-temperature superconducting coil 11 during normal operation (persistent current mode operation), thereby simplifying the cooling structure. It is composed of a superconducting wire.

The permanent current switch 14 is electrically insulated but thermally connected to a heater 18 for changing resistance according to temperature change. The persistent current switch 14 is heated to a superconducting transition temperature Tc or higher by the heating of the heater 18, thereby being brought into a normal conducting state (OFF) and generating a high resistance (OFF resistance). In the state where there is no heat input from the heater 18, the persistent current switch 14 is cooled to the same temperature as the high temperature superconducting coil 11 by thermal connection with a refrigerator (not shown) and becomes a superconducting state (on), and has a low resistance. (ON resistance). Persistent current mode operation in which current circulates in a closed loop including the high-temperature superconducting coil 11 and the persistent current switch 14 as indicated by arrow A is enabled by turning on the persistent current switch 14 .

The normal conducting resistor 15 is electrically connected in parallel to the persistent current switch 14 and thermally connected to the radiation shield 17 . The normal-conducting resistor 15 is installed inside or outside the radiation shield 17 , and in this embodiment, it is arranged in the cryogenic region M inside the radiation shield 17 . Since the normal-conducting resistor 15 is thermally connected to the radiation shield 17 as described above, it is cooled to the same temperature as the radiation shield 17, that is, about 40K to 70K.

The resistance value of the normal conducting resistor 15 is set higher than the resistance value of the protection resistor 13 and lower than the off resistance of the persistent current switch 14 . The reason why the resistance value of the normal conducting resistor 10 is set higher than the resistance value of the protective resistor 13 is that the current generated by the induced voltage generated in the high temperature superconducting coil 11 during excitation of the high temperature superconducting coil 11 is transferred to the normal conducting resistor 15 . This is to suppress the shunting of the current to lead to the protection resistor 13 .

The reason for setting the resistance value of the normal-conducting resistor 15 to be smaller than the OFF resistance of the persistent current switch 14 is as follows. That is, when an abnormality such as a breakage (indicated by a broken portion 21) occurs in a part of the cryogenic region M in the current supply line 20 that supplies current from the excitation power source 12 to the high-temperature superconducting coil 11, the high-temperature superconducting coil 11 In order to demagnetize the high-temperature superconducting coil 11, the persistent current switch 14 is forcibly quenched by raising the temperature to the superconducting transition temperature Tc or higher by the heater 18, and the persistent current switch 14 generates an off resistance. This is because the current flowing to the current switch 14 is diverted, as indicated by arrow B, to the normal conducting resistor 15 having a smaller resistance, and the magnetic energy of the high-temperature superconducting coil 11 is consumed by the normal conducting resistor 15 .

As a material of the normal conducting resistor 15, for example, a normal conducting metal such as gold, silver, copper, iron, stainless steel, aluminum, copper alloy such as brass or iron alloy, ceramics, or a semiconductor is used. In addition, the normal conducting resistor 15 may be formed by attaching a tape-shaped normal conducting wire to the above-described normal conducting metal, ceramics, or semiconductor to adjust the resistance value of the normal conducting resistor 15 . It is preferable to interpose an insulating material between the normal-conducting resistor 15 and the radiation shield 17 to electrically insulate the normal-conducting resistor 15 and the radiation shield 17 to prevent a ground fault. may not exist.

With the configuration as described above, the first embodiment has the following effect (1).
(1) When an abnormality such as a rupture (indicated by a rupture point 21) occurs in the current supply line 20 that supplies current from the excitation power supply 12 to the high-temperature superconducting coil 11, for example, in a part of the cryogenic region M, the high-temperature superconducting In order to demagnetize the coil 11, the temperature of the persistent current switch 14 is increased to the superconducting transition temperature Tc or higher to forcibly quench it. Mainly consumed by body 15 . Since the normal-conducting resistor 15 is thermally connected to the radiation shield 17 having a large heat capacity, the Joule heat generated in the normal-conducting resistor 15 is absorbed by the radiation shield 17, and the normal-conducting resistor The temperature rise due to Joule heat generation of 15 is suppressed, and the thermal stability is improved.

As a result, the permanent current switch 14 can be prevented from thermal runaway due to an excessive temperature rise during forced quenching, and the normal conducting resistor 15 consumes the magnetic energy of the high temperature superconducting coil 11, so that the high temperature superconducting coil 11 The high-temperature superconducting coil 11 can be demagnetized in a short time compared to the case where the magnetic energy of the high-temperature superconducting coil 11 is consumed by the minute resistance component of .

[B] Second embodiment (Fig. 2)
FIG. 2 is an electric circuit diagram showing a superconducting magnet device according to a second embodiment. In the second embodiment, the same parts as in the first embodiment are denoted by the same reference numerals as in the first embodiment, so that the explanation is simplified or omitted.

A high-temperature superconducting magnet device 25 as a superconducting magnet device of the second embodiment differs from the first embodiment in that the normal conducting resistor 15 is provided with temperature control means 26 capable of controlling the temperature of the normal conducting resistor 15. It is a set point.

As the temperature control means 26, for example, a heater as shown in FIG. be. In addition, as the temperature control means 26, a temperature-adjustable gas or refrigerant is used, and the normal-conducting resistor 15 is enclosed in a gas atmosphere or refrigerant, and the temperature of the gas or refrigerant is adjusted. 15 temperature may be changed.

By controlling (changing) the temperature of the normal-conducting resistor 15 by the temperature control means 26, the resistance value of the normal-conducting resistor 15 is changed. It becomes possible to increase the resistance value.

As described above, according to the second embodiment, the same effect as the effect (1) of the first embodiment can be obtained, and the high-temperature superconducting coil 11 can be completed in a shorter time than the first embodiment. can be demagnetized.

(2) When an abnormality such as a rupture (indicated by a rupture point 21) occurs in a part of the cryogenic region M in the current supply line 20, the persistent current switch 14 is turned to superconductivity to demagnetize the high-temperature superconducting coil 11. When the temperature is raised to the transition temperature Tc or higher for forced quenching, the resistance value of the normal conducting resistor 15 is increased by the temperature control means 26 to demagnetize the high temperature superconducting coil 11. The attenuation time constant of the current flowing through the resistor 15 can be shortened (smaller). The attenuation time constant is L/R, where L is the value of the inductance 11L of the high temperature superconducting coil 11 and R is the sum of the resistance value of the resistance component 11R of the high temperature superconducting coil 11 and the resistance value of the normal conducting resistor 15. Therefore, it becomes shorter (smaller) as the sum R of the resistance values increases.

In this way, the attenuation time constant of the current flowing from the high-temperature superconducting coil 11 to the normal conducting resistor 15 for demagnetizing the high-temperature superconducting coil 11 is shortened, and the above-mentioned current rapidly decreases. 11 can be demagnetized in a shorter time than in the first embodiment.

[C] Third embodiment (Fig. 3)
FIG. 3 is an electric circuit diagram showing a superconducting magnet device according to a third embodiment. In the third embodiment, parts similar to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, thereby simplifying or omitting the description.

A high-temperature superconducting magnet device 30 as a superconducting magnet device of the third embodiment differs from the first embodiment in that the normal conducting resistor 15 and the radiation shield 17 are thermally connected to each other. The point is that a thermal switch 31 capable of adjusting the thermal resistance between the radiation shield 17 is provided.

The thermal switch 31 provides a part of the heat transfer path between the normal-conducting resistor 15 and the radiation shield 17 that strengthens or weakens the thermal connection, thereby controlling the heat between the normal-conducting resistor 15 and the radiation shield 17. It is constructed so that the resistance can be adjusted. For example, the thermal switch 31 has a mechanical configuration in which the connecting surfaces are mechanically contacted or separated, a configuration in which the connecting surfaces are brought into contact or non-contact by allowing gas or liquid to flow into and out of the gap, or a configuration in which the connecting surfaces are brought into contact or non-contact with each other, or a solid material is used. For example, by thermally expanding or thermally contracting, the connecting surfaces are brought into contact or non-contact with each other.

When the temperature of the persistent current switch 14 is increased to the superconducting transition temperature Tc or higher to forcibly quench the high-temperature superconducting coil 11, the thermal switch 31 reduces the thermal resistance between the normal-conducting resistor 15 and the radiation shield 17. By adjusting, the thermal resistance between the normal-conducting resistor 15 and the radiation shield 17 is set to be smaller than the thermal resistance between the normal-conducting resistor 15 and the persistent current switch 14 . As a result, the Joule heat generated in the normal-conducting resistor 15 is easily transmitted to the radiation shield 17 and is less likely to be transmitted to the persistent current switch 14 .

With the above configuration, according to the third embodiment, the same effect as the effect (1) of the first embodiment can be obtained, and the temperature rise of the persistent current switch 14 can be suppressed more reliably. The effect (3) of

(3) In the event that an abnormality such as a rupture (indicated by a rupture point 21) occurs in the current supply line 20, for example, in part of the cryogenic region M, the persistent current switch 14 is turned into superconductivity to demagnetize the high-temperature superconducting coil 11. When the temperature is raised to the transition temperature Tc or higher for forced quenching, the thermal switch 31 causes the thermal resistance between the normal-conducting resistor 15 and the radiation shield 17 to change to that between the normal-conducting resistor 15 and the persistent current switch 14. is adjusted to be smaller than the thermal resistance of Therefore, the Joule heat generated in the normal conducting resistor 15 is easily transmitted to the radiation shield 17 and is difficult to be transmitted to the persistent current switch 14 . As a result, the temperature rise of the persistent current switch 14 can be more reliably suppressed, and its thermal runaway can be reliably prevented.

[D] Fourth embodiment (Fig. 4)
FIG. 4 is an electric circuit diagram showing a superconducting magnet device according to a fourth embodiment. In the fourth embodiment, the same parts as in the first embodiment are denoted by the same reference numerals as in the first embodiment to simplify or omit the description.

The high temperature superconducting magnet device 40 as the superconducting magnet device of the fourth embodiment differs from the first embodiment in that the normal conducting resistor 41 is replaced with the permanent current switch 14 similarly to the normal conducting resistor 15 of the first embodiment. and thermally connected to the radiation shield 17. A diode 42 is electrically connected in series to the normal conducting resistor 41, and the forward direction of the diode 42 is connected to the high temperature superconducting coil. 11 to the normal-conducting resistor 41 (direction of arrow B).

Diode 42 generally has the characteristic that current does not flow even in the forward direction unless the voltage acting on diode 42 is equal to or higher than a specified voltage. Therefore, even if an induced voltage is generated in the high-temperature superconducting coil 11 while the high-temperature superconducting coil 11 is being excited, the induced voltage is lower than the specified voltage of the diode 42. It is blocked by 42 and flows to the protection resistor 13 without being shunted to the normal conducting resistor 41 . Therefore, it is possible to set the resistance value of the normal-conducting resistor 41 to a value smaller than that of the normal-conducting resistor 15 of the first to third embodiments.

With the above configuration, according to the fourth embodiment, the same effect as the effect (1) of the first embodiment can be obtained, and the following effect of further suppressing the temperature rise of the persistent current switch 14 can be obtained. Play (4).

(4) When an abnormality such as a rupture (indicated by a rupture point 21) occurs in a part of the cryogenic region M in the current supply line 20, the persistent current switch 14 is turned to superconductivity to demagnetize the high-temperature superconducting coil 11. When the temperature is raised to the transition temperature Tc or higher to forcibly quench, the resistance value of the normal conducting resistor 41 is set smaller than the normal conducting resistor 15 of the first to third embodiments, so the high temperature superconducting coil 11 is demagnetized. The current flowing from the high-temperature superconducting coil 11 is promoted to be shunted to the normal conducting resistor 41 rather than to the persistent current switch 14 . As a result, the temperature rise of the persistent current switch 14 can be further suppressed than in the first to third embodiments, and the thermal runaway can be reliably prevented.

[E] Fifth embodiment (Figs. 5 and 6)
FIG. 5 is an electric circuit diagram showing a superconducting magnet device according to a fifth embodiment. In the fifth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, thereby simplifying or omitting the description.

A high-temperature superconducting magnet device 50 as a superconducting magnet device of the fifth embodiment differs from the first embodiment in that a normal-conducting resistor 51 is electrically connected to the persistent current switch 14 as in the first to fourth embodiments. and thermally connected to the radiation seal 17, and a portion 51A (FIG. 6) of the normal conducting resistor 51 is set to have a smaller cross-sectional area than the other portion 51B. The difference is that an insulating cover 52 is provided around the normal-conducting resistor 51 excluding the thermal connection portion between the resistor 51 and the radiation shield 17 .

As shown in FIG. 6, a portion 51A of the normal-conducting resistor 51 is set to have a smaller cross-sectional area than the other portion 51B, so that the portion 51A of the normal-conducting resistor 51 is more electrically conductive than the other portion 51B. Its resistance increases, it becomes easy to generate heat, and it becomes possible to melt it like a fuse.

The insulating cover 52 prevents the arc from scattering around when the portion 51A of the normal conducting resistor 51 is fused and an arc is generated at this fused portion. By covering the periphery of the normal conducting resistor 51 with the cover 52 , the parts other than the normal conducting resistor 51 in the high-temperature superconducting magnet device 50 are prevented from being damaged by the arc. As a material for the cover 52, a material having high heat resistance such as glass fiber reinforced plastic, reinforced PTFE (polytetrafluoroethylene), ceramics, or the like is suitable.

With the above configuration, according to the fifth embodiment, the same effect as the effect (1) of the first embodiment can be obtained, and the following effect can be obtained in which the high temperature normal conducting coil 11 can be demagnetized in a shorter time. Play (5).

(5) When an abnormality such as a rupture (indicated by a rupture point 21) occurs in a part of the cryogenic region M in the current supply line 20, the persistent current switch 14 is turned to superconductivity to demagnetize the high-temperature superconducting coil 11. When the temperature is raised to the transition temperature Tc or higher for forced quenching, the current flowing from the high-temperature superconducting coil 11 to the normal-conducting resistor 51 in order to demagnetize the high-temperature superconducting coil 11 intentionally causes the portion 51A of the normal-conducting resistor 51 to demagnetize. Thermal runaway and fusing. As a result, the magnetic energy of the high-temperature superconducting coil 11 can be instantaneously demagnetized by generating an arc at the fused portion of the normal conducting resistor 51. It can be realized in a shorter time than in the case of the embodiment.

Although several embodiments of the invention have been described above, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention, and these replacements and changes can be made. is included in the scope and gist of the invention, and is included in the scope of the invention described in the claims and its equivalents.

For example, the high-temperature superconducting magnet devices 10, 25, 30, 40, and 50 are not limited to a single high-temperature superconducting coil 11, and even if a plurality of high-temperature superconducting coils 11 are electrically connected in series or in parallel. , the present invention can be applied. Among them, when a plurality of high-temperature superconducting coils 11 are connected in series, a plurality of persistent current switches 14 are provided electrically in parallel to each high-temperature superconducting coil 11, and normal conducting resistors 15, 41, 51 are connected to each other. It is preferable that a plurality of permanent current switches 14 are provided electrically in parallel.

DESCRIPTION OF SYMBOLS 10... High temperature superconducting magnet apparatus (superconducting magnet apparatus), 11... High temperature superconducting coil (superconducting coil), 12... Excitation power supply, 13... Protective resistance, 14... Permanent current switch, 15... Normal conducting resistor, 16... Vacuum container, 17... Radiation shield 20... Current supply line 25... High temperature superconducting magnet device (superconducting magnet device) 26... Temperature control means 30... High temperature superconducting magnet device (superconducting magnet device) 31... Thermal switch 40... High temperature superconductivity Magnet device (superconducting magnet device) 41 Normal-conducting resistor 42 Diode 50 High-temperature superconducting magnet device (superconducting magnet device) 51 Normal-conducting resistor 51A Part of normal-conducting resistor 51B Normal Other parts of the conductive resistor, 52...insulator cover.

Claims (9)

A vacuum vessel, a radiation shield provided in the vacuum vessel, a superconducting coil provided in the radiation shield, an excitation power supply for supplying current to the superconducting coil, and electrically connected in parallel to the superconducting coil. and a persistent current switch provided in the radiation shield,
a resistive resistor electrically connected in parallel to the persistent current switch and thermally connected to the radiation shield ;
A protection resistor provided in a room temperature region is connected in parallel to the excitation power source, and the resistance value of the normal conducting resistor is greater than the resistance value of the protection resistor and higher than the off resistance of the persistent current switch. A superconducting magnet device characterized by being set small . A vacuum vessel, a radiation shield provided in the vacuum vessel, a superconducting coil provided in the radiation shield, an excitation power supply for supplying current to the superconducting coil, and electrically connected in parallel to the superconducting coil. and a persistent current switch provided in the radiation shield,
a resistive resistor electrically connected in parallel to the persistent current switch and thermally connected to the radiation shield;
A superconducting magnet apparatus, wherein the normal conducting resistor is provided with temperature control means capable of controlling the temperature of the normal conducting resistor . A vacuum vessel, a radiation shield provided in the vacuum vessel, a superconducting coil provided in the radiation shield, an excitation power supply for supplying current to the superconducting coil, and electrically connected in parallel to the superconducting coil. and a persistent current switch provided in the radiation shield,
a resistive resistor electrically connected in parallel to the persistent current switch and thermally connected to the radiation shield;
A superconducting magnet , wherein a thermal switch capable of adjusting thermal resistance between the normal conducting resistor and the radiation shield is provided at a thermal connection portion between the normal conducting resistor and the radiation shield. Device. The superconducting coil according to any one of claims 1 to 3, wherein the superconducting coil is a high temperature superconducting coil made of a high temperature superconducting wire, and the persistent current switch is made of the high temperature superconducting wire. A superconducting magnet device as described. The thermal resistance between the normal conducting resistor and the radiation shield is set smaller than the thermal resistance between the normal conducting resistor and the persistent current switch during forced quenching of the persistent current switch. The superconducting magnet device according to claim 3 . 6. A diode is connected in series with said normal-conducting resistor, and the forward direction of this diode is set to match the direction of the current flowing from the superconducting coil to said normal - conducting resistor. The superconducting magnet device according to any one of . 7. A superconducting magnet apparatus according to any one of claims 1 to 6 , wherein a portion of said normal-conducting resistor has a smaller cross-sectional area than other portions. 8. The superconducting magnet apparatus according to claim 7 , wherein an insulating cover is provided around said normal conducting resistor except for a thermal connection portion between said normal conducting resistor and said radiation shield. 9. A superconducting magnet apparatus according to any one of claims 1 to 8 , wherein said normal conducting resistor is installed inside or outside a radiation shield.

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