JPH10189328A - Superconducting magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconducting magnet which hardly cause superconducting quenching and, at the same time, to suppress the voltage generated in a superconducting coil when superconducting quenching occurs by accelerating the propagation of the superconducting quenching. SOLUTION: On the surfaces of superconducting coils 1a and 1b to which the electromagnetic force generated the coils 1a and 1b is applied, cooling and soaking members 10a and 10b having excellent thermal conductivity are provided so as to cool the surfaces of the coils. In addition, a coil protective element connected to both ends of a current terminal which supplies an electric current to the coils 1a and 1b is provided so as to heat the coils 1a and 1b with the heat generated from the element due to an electric current flowing through the element when superconducting quenching occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting magnet and, more particularly, to a countermeasure against a phenomenon in which a superconducting coil is destroyed by superconductivity.

[0002]

2. Description of the Related Art FIG. 11 shows, for example, Japanese Patent Application Laid-Open No. 8-78737.
FIG. 1 is a cross-sectional view showing a conventional superconducting magnet disclosed in Japanese Patent Laid-Open Publication No. H10-209,004. This device has, for example, two superconducting coils. In the figure, reference numeral 1 denotes a superconducting coil. In this case, two superconducting coils 1a, 1b, 2 are winding frames for supporting the superconducting coil 1, and winding frames 2a, 2b are provided for the superconducting coils 1a, 1b. I have. 4 is a superconducting coil 1
5 is a vacuum tank that holds a vacuum for thermal insulation, 6 is a cooling source that cools the superconducting coil 1, and is, for example, a Gifford McMahon cycle (G).
M) A refrigerator is applied. Reference numeral 9 denotes an electromagnetic force supporting member that supports an electromagnetic force generated between the superconducting coils 1a and Ib. Reference numeral 12 denotes a heat conductive member for thermally short-circuiting the cooling source 6 and the superconducting coil 1, 13 a magnetic shield for reducing leakage of the magnetic field generated by the superconducting coil 1 to the outside, and 14 a reel. Cooling member attached to 2,
Cooling members 14a, 14b are attached to the winding frames 2a, 2b, respectively. In the configuration shown in this figure, the central axes of the two superconducting coils 1a and 1b are the same, and are arranged shifted in the axial direction.

As shown in FIG. 1, a superconducting coil 1 is cooled from a cooling source 6 via a heat conducting member 12 and a cooling member 14. The superconducting coil 1 is housed inside the vacuum chamber 5, is kept in a vacuum state, and is insulated from the outside of the vacuum chamber 5. Further, radiation heat from room temperature is prevented from entering the superconducting coil 1 by the radiation shield 4 maintained at an intermediate temperature between the temperature of the superconducting coil 1 and room temperature.
Thus, the superconducting coil 1 is, for example, 5K (about -26
8 ° C.), the superconducting coil 1 is in a superconducting state. In this state, the superconducting coil 1
When a current is supplied to the superconducting coil 1, a magnetic field is generated, and since the electric resistance of the superconducting coil 1 is zero, almost no voltage is generated at the time of steady conduction, so that almost no power loss occurs.

Further, the superconducting magnet 1 is cooled by immersing the superconducting coil 1 directly in a refrigerant liquid using a cryogenic refrigerant such as liquid helium without using the cooling source 6 such as the GM refrigerator described above. There are also things.

[0005]

[0006] As in the conventional apparatus, 2
When the superconducting coil 1 is constituted by a plurality of superconducting coils 1, a large electromagnetic force is generated by the magnetic field generated by these superconducting coils 1, and when the central axis of the superconducting coil 1 is arranged coaxially, it is attracted or pulled Receives repulsive electromagnetic force. When the superconducting coil 1 receives such an electromagnetic force, one of the superconducting coils 1 is pressed against the bobbin 2 and the coil 1 becomes easy to move, and the superconducting coil 1 is easily heated and the superconducting coil 1 is easily destroyed. There was a problem.

In addition, since the magnetic material such as the magnetic shield 13 has a magnetic material, an attractive electromagnetic force is generated between the superconducting coil 1 and the magnetic shield 13, and the superconducting coil 1 is easily broken by superconductivity as described above. There was also.

Since the two superconducting coils 1a and 1b are thermally separated from each other, if one of the superconducting coils 1a is destroyed by superconductivity, the other superconducting coil 1b keeps the superconducting state. There is also a problem that a voltage corresponding to the inductance is generated due to the current decay, and dielectric breakdown is likely to occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a superconducting magnet in which superconducting breakdown hardly occurs and in which even if superconducting breaking occurs, dielectric breakdown is difficult.

[0009]

The superconducting magnet according to the first aspect of the present invention has the same central axis and is disposed shifted in the axial direction, and is cooled by a cooling source to be in a superconducting state. More than one superconducting coil, an electromagnetic force supporting member that supports the electromagnetic force generated between the superconducting coils, a cooling heat equalizing member that is fixed to the axial end face of the coil to which the electromagnetic force is applied and has good thermal conductivity to cool the superconducting coil It is a thing.

A superconducting magnet according to a second configuration of the present invention includes a superconducting coil which is cooled by a cooling source to be in a superconducting state, a magnetic material provided on at least one end in the axial direction of the superconducting coil, and a superconducting coil. An electromagnetic force supporting member for supporting an electromagnetic force generated between magnetic bodies, and a cooling heat equalizing member having good thermal conductivity fixed to an axial end surface of a coil to which the electromagnetic force is applied and cooling the superconducting coil.

A superconducting magnet according to a third configuration of the present invention is connected to both ends of a superconducting coil which is cooled by a cooling source to be in a superconducting state, and a current terminal for supplying a current to the superconducting coil. Are provided with a coil protection element that operates when a voltage equal to or higher than a predetermined voltage is applied to both ends of the coil, and the coil protection element is configured to be in thermal contact with the superconducting coil.

Further, in a superconducting magnet according to a fourth configuration of the present invention, in the third configuration, the coil protection element is configured to be in thermal contact with a low magnetic field portion of the superconducting coil.

A superconducting magnet according to a fifth aspect of the present invention has two or more superconducting coils which are cooled by a cooling source to be in a superconducting state, and a current terminal for supplying a current to the superconducting coil. A plurality of coil protection elements that operate when a voltage equal to or higher than a predetermined voltage is applied to both ends of the current terminal thereof, wherein the coil protection element connected to one of the superconducting coils is connected to at least one other superconducting coil. It is configured to be in thermal contact with the coil.

In the superconducting magnet according to a sixth aspect of the present invention, in the fifth aspect, each of the coil protection elements is configured to be in thermal contact with a high magnetic field portion of another superconducting coil. Things.

A superconducting magnet according to a seventh aspect of the present invention is the superconducting magnet according to any one of the first to sixth aspects, wherein the superconducting coil is cooled by heat conduction from a cooling source. is there.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, the superconducting magnet according to the first embodiment of the present invention will be described. FIG. 1 is a sectional view showing a superconducting magnet according to the present embodiment. This device has, for example, two superconducting coils. In the figure, reference numeral 1 denotes a superconducting coil. In this case, two superconducting coils 1a, 1b, 2 are winding frames for supporting the superconducting coil 1, and winding frames 2a, 2b are provided for the superconducting coils 1a, 1b. I have. Reference numeral 3 denotes a weight supporting material for supporting the weight of the superconducting coil 1, 4 denotes a radiation shield that blocks radiation to the superconducting coil 1, 5 denotes a vacuum chamber that holds a vacuum for heat insulation,
Reference numeral 7 denotes a cryogenic container for cooling the superconducting coil 1, and reference numeral 8 denotes a refrigerant stored in the cryogenic container 7, for example, liquid helium. Reference numeral 9 denotes an electromagnetic force supporting member, which is made of, for example, stainless steel and supports an electromagnetic force generated between the superconducting coils 1a and Ib. Reference numeral 10 denotes a cooling soaking member, which is made of, for example, copper or aluminum, and is cooled between the winding frames 2a, 2b and the superconducting coils 1a, 1b on the side where the other superconducting coil is disposed in the axial direction. Heat members 10a, 10b
Is installed.

In this superconducting magnet, for example,
When two superconducting coils 1 generate a magnetic field in the same direction, when the superconducting coils 1 are excited, an attractive force acts on both superconducting coils 1 in the vertical direction in the figure. FIG. 2 is an explanatory diagram schematically showing magnetic flux lines near the superconducting coil 1. The portion where the magnetic flux lines are dense is the portion where the magnetic field is strong, the both ends in the axial direction of the superconducting coil 1 are strong, and the electromagnetic force in the central portion in the axial direction is weak. The superconducting coil 1 is pressed down in one direction of the winding frame 2 by such an electromagnetic force, causing a slight displacement. At this time, the stress in the portion where the electromagnetic force is applied most is maximized, and heat is generated in that portion, and the superconducting state is destroyed due to a rise in temperature. It is said that this phenomenon of superconducting destruction is quenched.

In this embodiment, as shown in FIG. 1, a material having a high thermal conductivity, such as copper, is applied to a portion where electromagnetic force is applied between the bobbin 2 and the superconducting coil 1 by a cooling heat equalizing member 10.
It is arranged as. The cooling and heat equalizing member 10 is fixed to the end face of the superconducting coil 1 by bonding or mechanical pressure. When the superconducting coil 1 generates heat due to the displacement due to the electromagnetic force, the generated heat is diffused by the cooling and heat equalizing member 10, and the superconducting coil 1 is quickly exchanged with the refrigerant 8 to be cooled. For this reason, the temperature rise of the superconducting coil 1 can be suppressed, and quenching becomes difficult.

Since the superconducting coil 1 of this embodiment has an attractive force, a cooling and heat equalizing member 10 is disposed in the axial direction of the superconducting coil 1 on the end face on which the other superconducting coil 1 is provided. . On the other hand, in the case of a configuration in which a repulsive force acts, the other superconducting coil 1 extends in the axial direction of superconducting coil 1.
The cooling and heat equalizing member 1 is provided on the end face opposite to the side on which the
0 may be arranged. In some cases, the cooling and heat equalizing members 10 may be disposed on both end surfaces of the superconducting coil 1 in the axial direction.

In the above superconducting magnet, a metal material such as copper is used as the cooling and heat equalizing member 10. However, a ceramic having good thermal conductivity such as alumina may be used.
Further, a material having a high thermal conductivity such as a material close to a single crystal such as sapphire may be used, and the same effect as described above can be obtained.

Embodiment 2 FIG. Hereinafter, a superconducting magnet according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a sectional view showing the superconducting magnet according to the present embodiment. In the figure, reference numeral 6 denotes a cooling source for cooling the superconducting coil.
A superconducting coil 1 is conductively cooled through a heat conducting member 12 and a copper wire using a McMaffon cycle refrigerator (hereinafter referred to as a GM refrigerator). Reference numeral 11 denotes a magnetic material that shapes the magnetic field generated by the superconducting coil 1 or functions as a magnetic shield.

The superconducting magnet according to the present embodiment is
When the superconducting coil 1 is excited, an attractive force is generated between the superconducting coil 1 and the magnetic body 11. For this reason, a stress is generated in the superconducting coil 1 that presses against one side of the winding frame 2 on the side where the magnetic body 11 is disposed, and the superconducting coil 1 becomes easy to move. In the present embodiment, the cooling and heat equalizing member 10 is provided on the end surface of the superconducting coil 1 on the side where the magnetic body 11 is arranged. For this reason, when heat is generated between the reel 2 being held down,
The heat is diffused by the cooling soaking member 10 and the cooling source 6
The superconducting coil 1 is cooled by exchanging heat with the superconducting coil 1. Therefore, the temperature rise of the superconducting coil 1 can be prevented, and quenching becomes difficult.

Particularly, in the present embodiment, unlike the first embodiment, the periphery of superconducting coil 1 is not directly in contact with refrigerant 8. For this reason, the heat generated due to friction or the like is likely to cause the temperature of the superconducting coil 1 to rise immediately. On the other hand, in the present embodiment, since the cooling and heat equalizing member 10 having a high thermal conductivity is disposed in a portion where the stress is large, the heat generation is quickly diffused, and there is an effect of suppressing a temperature rise.

In the above configuration, the superconducting magnet that cools the superconducting coil 1 by the GM refrigerator 6 has been described. However, in the case of the immersion cooling type superconducting magnet using liquid helium as in the first embodiment, In the case where the superconducting coil 1 and the magnetic body 11 are used, by fixing the cooling and heat equalizing member 10 to a portion where heat is generated by an electromagnetic force, the same effect as in the above embodiment can be obtained.

Embodiment 3 Next, a superconducting magnet according to a third embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a sectional view showing a superconducting magnet according to the third embodiment. In the present embodiment, two superconducting coils 1a,
1b, and an electromagnetic force support member 9 for supporting the electromagnetic force applied between them is provided. The GM refrigerator 6 and the superconducting coil 1 are thermally connected via the heat conducting member 12, the copper wire, and the cooling / heating members 10a and 10b.

As shown in the figure, as in the second embodiment, the periphery of superconducting coil 1 is not in direct contact with the refrigerant. For this reason, the heat generated due to friction or the like is likely to cause the temperature of the superconducting coil 1 to rise immediately. In the present embodiment, on the other hand, a cooling and heat equalizing member 10 having a high thermal conductivity is arranged in a portion where heat such as friction is likely to be generated in the vicinity of a large electromagnetic force of superconducting coil 1. For this reason, the generated heat is quickly diffused and has an effect of suppressing a rise in temperature. The periphery of the superconducting coil 1 is in an adiabatic state, and the heat generated at the coil end surface of the superconducting coil 1 is diffused and cooled by the cooling and heat equalizing member 10. Extremely large compared to coils.

The configuration of the present embodiment is a configuration in the case where the superconducting coil 1 receives a repulsive force.
0 is set on the surface to which the repulsive force stress is applied.

Embodiment 4 Next, a superconducting magnet according to a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a sectional view showing a superconducting magnet according to the fourth embodiment. In the figure, 15 is a coil protection element, and 16 is a good heat conducting member such as heat conducting grease. FIG. 6 is a circuit diagram showing an example of a configuration having the coil protection element 15. In the figure, reference numeral 17 denotes an excitation power supply, and the inside of a dotted line indicates an extremely low temperature portion. As shown in the figure, the coil protection element 15 is electrically connected to both ends of a current terminal for supplying a current to the superconducting coil 1, and is turned on when a certain constant voltage of about 2 to 10 V is applied. This is a short-circuit, for example, a diode element. The coil protection element 15 is in thermal contact with the superconducting coil 1 by the good heat conducting member 16.

FIG. 7 is a graph showing the cryogenic characteristics of the coil protection element 15, in which the horizontal axis represents voltage and the vertical axis represents current. When a part of the superconducting coil 1 is quenched for some reason, a voltage of several V is generated at both ends of the superconducting coil 1. When a voltage equal to or higher than the turn-on voltage is applied to both ends of the superconducting coil 1, the coil protection element 15 connected to both ends is turned on, and the voltage at both ends immediately drops to 0.2V as shown in FIG. Then, a current flows through the coil protection element 15, and a voltage higher than a turn-on voltage is prevented from being generated at both ends of the superconducting coil 1, thereby preventing an overvoltage. In this state, the voltage at both ends of the superconducting coil 1 decreases, but the superconducting portion and the normal conducting portion coexist inside the coil, and are expressed by the following equation.

[0030]

(Equation 1)

In Equation 1, V is the coil voltage, L is the inductance of the coil, R (t) is the resistance of the superconducting coil due to quench, and i is the current. When the superconducting coil 1 is quenched, di / dt becomes negative and i is positive. Thus, a negative voltage is induced in the superconducting portion due to the inductance component of the coil. If the transition speed of the normal conduction state in the superconducting portion is low, an excessive voltage is generated inside the superconducting coil 1 due to the induced voltage, and the superconducting coil 1 may be broken.

In this embodiment, when a part of the superconducting coil 1 is quenched, a current flows through the coil protection element 15 and the coil protection element 15 generates heat. Since this heat is in thermal contact of the coil protection element 15 with the superconducting coil 1 via the good heat conduction member 16, the coil protection element 1
The superconducting coil 1 is heated by the heat generated in 5, and the quench speed is accelerated. This allows the superconducting coil 1
Is not quenched, a resistance is generated in the superconducting coil 1, and the generated voltage in the superconducting coil is reduced. That is, the induced voltage generated in the superconducting coil 1 is R
The superconducting coil 1 is reduced by the positive voltage of (i).
Is prevented from being damaged by voltage.

As described above, in the present embodiment, when a quench occurs, the entire superconducting coil 1 is rapidly transferred to the normal conduction state, and the superconducting portion and the normal conducting portion are mixed in the superconducting coil 1. Is prevented, it is possible to prevent the superconducting coil 1 from being broken by a voltage.

Further, in the present embodiment, the coil protection element 15 is particularly provided in the portion of the superconducting coil 1 where the magnetic field is lowest. This is because the magnetic flux lines near the superconducting coil 1 are schematically shown in FIG. 2, and the magnetic flux lines are coarse at the center of the superconducting coil 1 and the magnetic field is low. Generally, in the superconducting coil 1, the highest portion of the generated magnetic field is easily quenched, and the portion of the lower magnetic field is hardly quenched. Therefore, when the coil protection element 15 is installed in a portion where the magnetic field is low, when a part of the superconducting coil 1 is quenched, the coil protection element 15 is turned on and generates heat, thereby quenching from the vicinity where the element is mounted. That is, by heating a low magnetic field portion that is difficult to quench, the entire superconducting coil 1 is quickly quenched to generate resistance. Then, since the portion where R (i) occurs is dispersed as shown in Expression 1, the generated voltage in superconducting coil 1 can be further reduced, and superconducting coil 1 can be prevented from being broken by the voltage.

Embodiment 5 FIG. Hereinafter, a superconducting magnet according to a fifth embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a sectional view showing the superconducting magnet according to the present embodiment. In the present embodiment, a plurality of superconducting coils 1a,
1b relates to a superconducting magnet, for example, a superconducting magnet having two superconducting coils. In the figure, coil protection elements 15a, 15b electrically connected to both ends of a current lead for supplying a current to each superconducting coil 1a, 1b are connected to other superconducting coils 1b, 1a which are not electrically connected. Good heat conduction member 16
a, 16b so as to be in thermal contact with each other.

FIG. 9 is a circuit diagram showing an example of a configuration having the coil protection elements 15a and 15b. FIG. 9A shows a normal connection state, and FIG. 9B shows one superconducting coil 1a.
FIG. 4 is a circuit diagram when quenching occurs. In the figure, 17
Denotes an excitation power supply, and a dotted line indicates a cryogenic part. Each of dotted lines connecting the coil protection elements 15a, 15b and the superconducting coils 1b, 1a indicates that they are in thermal contact. In the figure, arrows indicate the direction of current flow. FIG.
As shown in the figure, the coil protection element 15a is electrically connected to both ends of a current terminal for supplying current to the superconducting coil 1a, and the coil protection element 15b is electrically connected to both ends of a current terminal for supplying current to the superconducting coil 1b. Connected.
When a certain voltage of about 2 to 10 V is applied to this current terminal, the coil protection element 15 is turned on, and both ends are electrically short-circuited, and a current flows as shown in FIG. 9B. Then, the coil protection element 15a generates heat, and this element 15a
The superconducting coil 1b that is in thermal contact with is heated to be quenched.

When a plurality of coils are used, a voltage generated in a certain coil is represented by the following equation (2). Equation 2
In the above, M is a mutual inductance with another coil.

[0038]

(Equation 2)

In such a configuration, when one of the superconducting coils, for example, the superconducting coil 1a is quenched, the superconducting coils are thermally separated from each other as shown in Equation 2, so that the other superconducting coil 1b is not quenched and R Since (t) = 0, an excessively negative voltage is generated, which is dangerous. However, in the present embodiment, the coil protection elements 1 connected to both ends of the superconducting coil 1a quenched as described above.
Since 5a is placed in thermal contact with the non-quenched superconducting coil 1b, the non-quenched superconducting coil 1b is heated and quenched. As a result, a positive voltage is generated in the superconducting coil 1b, so that the voltage of the superconducting coil 1b that has not been quenched can be reduced.

When three or more superconducting coils are used, the coil protection element connected to the current terminal of one superconducting coil is brought into thermal contact with all the other superconducting coils. I just need. When a plurality of superconducting coils 1 are connected in series, the coil protection element 1
5 has the same effect as that of the above-described embodiment if it is attached so as to be in thermal contact with the superconducting coil 1 connected next to it. This is because, when a plurality of superconducting coils 1 are connected in series and coil protection elements 15 are connected to both ends of each superconducting coil 1, when a certain superconducting coil is quenched, both ends of the superconducting coil that are not quenched are A voltage is induced, and the coil protection element 15 is turned on by the voltage, and a current flows to generate heat. The superheated coils that have not been quenched due to this heat are sequentially quenched, and an effect of preventing an overvoltage from occurring is achieved.

Embodiment 6 FIG. Hereinafter, a superconducting magnet according to a sixth embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a sectional view showing a superconducting magnet according to the present embodiment. As shown in FIG.
For example, in the present embodiment, two superconducting coils 1a and 1b
It is composed of The coil protection element 15a is electrically connected to both ends of a current lead for supplying a current to the superconducting coil 1a, and the coil protection element 15b is connected to the superconducting coil 1b.
Are electrically connected to both ends of a current lead for supplying a current to the power supply. Further, in the present embodiment, the coil protection element 15a is provided with the electrically connected superconducting coil 1a.
The superconducting coil 1b is attached so as to be in thermal contact with the high magnetic field portion of the other superconducting coil 1b. Similarly, the coil protection element 15b is attached so as to be in thermal contact with the high magnetic field portion of the superconducting coil 1a.

For example, it is assumed that the superconducting coil 1a is quenched. In order to quickly quench the superconducting coil 1b that is not thermally connected to the superconducting coil 1a,
It is efficient to heat the high magnetic field portion of the superconducting coil 1b. This is because, as described above, the low magnetic field portion of the superconducting coil is hard to quench, and the high magnetic field portion is easily quenched by a little heat. In the present embodiment, since the coil protection element 15 as the heating means is installed in the high magnetic field portion of the superconducting coil 1 to be quenched, when one superconducting coil is quenched, the unconducted superconducting coil 1 is removed. It has the effect of quenching quickly.

In this embodiment, the coil protection element 15 is attached to the surface of the cooling and heat equalizing member 10 installed in the high magnetic field portion as shown in FIG.
5 may be embedded in the cooling and heat equalizing member 10, and the same effect as in the above-described embodiment can be obtained.

In Embodiments 4 to 6, when superconducting coil 1 is cooled by heat conduction from cooling source 6, superconducting coil 1 is insulated and no refrigerant exists. Heat conduction in the superconducting coils 1 or in the space between the superconducting coils 1 is poor. For this reason, all the heat generated by the coil protection element 15 is directly transmitted to the superconducting coil 1, and the coil protection element 15 promotes the quench more efficiently than a superconducting coil cooled with a coolant, for example, liquid helium. Is extremely large.

[0045]

As described above, according to the first configuration of the present invention, two components having the same central axis, which are arranged to be shifted in the axial direction, are cooled by a cooling source and are brought into a superconducting state. The superconducting coil, an electromagnetic force supporting member for supporting an electromagnetic force generated between the superconducting coils, a cooling heat equalizing member having good thermal conductivity fixed to an axial end face of the coil to which the electromagnetic force is applied and cooling the superconducting coil. Thereby, there is an effect that the portion to which the electromagnetic force is applied is actively cooled, and a superconducting magnet which is hardly damaged by superconductivity is obtained.

Further, according to the second configuration of the present invention, a superconducting coil which is cooled by a cooling source to be in a superconducting state, a magnetic material provided at least at one end in the axial direction of the superconducting coil, the superconducting coil and the magnetic material Electromagnetic force is applied by providing an electromagnetic force support member that supports an electromagnetic force generated therebetween, and a cooling heat equalizing member that is fixed to the axial end surface of the coil to which the electromagnetic force is applied and has good thermal conductivity to cool the superconducting coil. There is an effect that the portion is positively cooled to obtain a superconducting magnet which is hardly broken by superconductivity.

According to the third configuration of the present invention, the superconducting coil which is cooled by the cooling source to be in a superconducting state, is connected to both ends of a current terminal for supplying a current to the superconducting coil, and is connected to both ends of the current terminal. A coil protection element that operates when a voltage equal to or higher than a predetermined voltage is applied to the coil, and the coil protection element is configured to be in thermal contact with the superconducting coil. There is an effect that a superconducting magnet that can promote propagation and reduce the voltage in the coil and prevent dielectric breakdown can be obtained.

According to the fourth configuration of the present invention, the third configuration
By configuring the coil protection element in the configuration of the above to be in thermal contact with the low magnetic field portion of the superconducting coil,
There is an effect that a superconducting magnet that can effectively promote the propagation of superconducting breakdown can be obtained.

Further, according to the fifth configuration of the present invention, two or more superconducting coils which are cooled by a cooling source to be in a superconducting state, and are connected to both ends of a current terminal for supplying a current to the superconducting coil. A plurality of coil protection elements that operate when a voltage equal to or higher than a predetermined voltage is applied to both ends of the current terminal, wherein the coil protection element connected to one of the superconducting coils is connected to at least one other superconducting coil. In the configuration having a plurality of superconducting coils, when one superconducting coil is destroyed by superconductivity, the propagation of the breakdown is promoted, the voltage in all the coils is reduced, and the dielectric breakdown is reduced. This has the effect of obtaining a superconducting magnet that can be prevented.

According to the sixth configuration of the present invention, the fifth configuration
Each of the coil protection elements in the above configuration is configured to be in thermal contact with a high magnetic field portion of another superconducting coil, so that a superconducting magnet that can effectively promote the propagation of superconducting breakdown is obtained. .

According to the seventh configuration of the present invention, the first
Or the superconducting coil in any one of the sixth to sixth configurations,
With the configuration in which cooling is performed by heat conduction from the cooling source, there is an effect that a superconducting magnet that can effectively cope with the phenomenon of superconducting breakdown of the superconducting coil is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a superconducting magnet according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing magnetic flux lines near a superconducting coil according to the first embodiment.

FIG. 3 is a sectional view showing a superconducting magnet according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a superconducting magnet according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a superconducting magnet according to a fourth embodiment of the present invention.

FIG. 6 is a main circuit diagram including a coil protection element according to a fourth embodiment.

FIG. 7 is a graph showing cryogenic characteristics of the coil protection element according to the fourth embodiment.

FIG. 8 is a sectional view showing a superconducting magnet according to a fifth embodiment of the present invention.

FIG. 9 is a main circuit diagram including a coil protection element according to a fifth embodiment.

FIG. 10 is a sectional view showing a superconducting magnet according to a sixth embodiment of the present invention.

FIG. 11 is a sectional view showing a conventional superconducting magnet.

[Explanation of symbols]

1, 1a, 1b superconducting coil, 2, 2a, 2b winding frame, 5 vacuum vessel, 6 cooling source, 7 cryogenic vessel, 8 refrigerant, 9 electromagnetic force support member, 10, 10a, 10b cooling soaking member, 11 magnetism Body, 12 heat conducting members, 15, 1
5a, 15b Coil protection element 16, 16a, 16b
Good heat conductive member.

Claims (7)

[Claims] 1. Two or more superconducting coils which have the same central axis and are displaced in the axial direction, are cooled by a cooling source and are brought into a superconducting state, and support an electromagnetic force generated between the superconducting coils. A superconducting magnet comprising: an electromagnetic force supporting member; and a cooling member having good thermal conductivity and fixed to an axial end surface of the coil to which the electromagnetic force is applied, and cooling the superconducting coil. 2. A superconducting coil which is cooled by a cooling source to be in a superconducting state, a magnetic body provided on at least one end in an axial direction of the superconducting coil, and an electromagnetic force generated between the superconducting coil and the magnetic body. A superconducting magnet comprising: an electromagnetic force supporting member; and a cooling member having good thermal conductivity and fixed to an axial end surface of the coil to which the electromagnetic force is applied, and cooling the superconducting coil. 3. A superconducting coil that is cooled by a cooling source to be in a superconducting state, and is connected to both ends of a current terminal for supplying a current to the superconducting coil, and when a voltage equal to or higher than a predetermined voltage is applied to both ends of the current terminal. A superconducting magnet, comprising: an operating coil protection element, wherein the coil protection element is configured to be in thermal contact with the superconducting coil. 4. The superconducting magnet according to claim 3, wherein the coil protection element is configured to be in thermal contact with a low magnetic field portion of the superconducting coil. 5. A superconducting state when cooled by a cooling source 2
A plurality of superconducting coils, and a plurality of coil protection elements that are connected to both ends of a current terminal that supplies a current to the superconducting coil and that operate when a voltage of a predetermined voltage or more is applied to both ends of the current terminal. A superconducting magnet, wherein a coil protection element connected to one of the superconducting coils is configured to be in thermal contact with at least one other superconducting coil. 6. The superconducting magnet according to claim 5, wherein each of the coil protection elements is configured to be in thermal contact with a high magnetic field portion of the other superconducting coil. 7. The superconducting magnet according to claim 1, wherein the superconducting coil is cooled by heat conduction from a cooling source.