JPH0878737A - Superconductive magnet - Google Patents

Abstract

PURPOSE: To enhance performance and reliability in a superconductive magnet provided with a cool-storing refrigerator having a magnetic cool-storing material. CONSTITUTION: A superconductive coil 1 is enclosed with a radiation shield 4, which is enclosed with a vacuum tub 5. The superconductive coil 1 and radiation shield 4 are cooled by a cool-storing refrigerator 27 having a magnetic cool-storing material. A magnetic field generating the superconductive coil 1 is shielded by a magnetic shield 30, and the cool-storing refrigerator 27 is arranged on the reverse side to the superconductive coil 1 with respect to the magnetic shield 30. Further, the superconductive coil 1 is thermally connected with a low temperature side stage 8 via a conductive member. Further, a superconductive magnet comprises a refrigerator unit and a superconductive coil unit.

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 superconducting magnet having a regenerator.

[0002]

22 is a sectional view showing an example of a conventional superconducting magnet disclosed in Japanese Patent Laid-Open No. 6-132567. In the figure, 1 is a superconducting coil, 2 is a reel for winding the superconducting coil 1, 3a is a low temperature side current lead for supplying a current to the superconducting coil 1, 3b is a high temperature side current lead for supplying a current to the superconducting coil 1, 4 is a Superconducting coil 1
2 is a vacuum chamber that surrounds the radiation shield 4, 6 is a two-stage Gifford-McMahon cycle refrigerator (hereinafter, two-stage refrigerator), which is a kind of regenerator that cools the superconducting coil 1 and the radiation shield 4. GM refrigerator), 7 is a compressor for supplying working gas to the two-stage GM refrigerator 6, 8 is a low temperature side stage of the two-stage GM refrigerator 6,
Reference numeral 9 is a high temperature side stage of the two-stage GM refrigerator 6, 10 is a power source of the superconducting coil 1, 31 is an intermediate temperature portion of the current lead 3, and is configured to be in thermal contact with the radiation shield 4.

Next, the operation of the conventional superconducting magnet will be described. The superconducting coil 1 is in thermal contact with the low temperature side stage 8 of the two-stage GM refrigerator 6 and is in the two-stage GM refrigerator 6.
Causes the material to be cooled to an extremely low temperature (for example, 4.2K) and has a zero electric resistance, that is, a so-called superconducting state. So the current lead 3
An exciting current is supplied to the superconducting coil 1 from an external superconducting coil power source 10 via a and 3b to generate a desired magnetic field. Since the superconducting coil 1 has zero electric resistance, it does not generate Joule heat by itself even when a current is passed. However, heat enters the superconducting coil 1 from the outside due to convection, radiation, and conduction, and it is desirable to reduce this heat penetration as much as possible.

In order to reduce heat invasion into the superconducting coil 1, the superconducting coil 1 is housed in a vacuum chamber 5 to block heat intrusion due to convection. Further, a radiation shield 4 is provided to surround the superconducting coil 1 so that the radiant heat does not directly enter the superconducting coil 1 from the vacuum chamber 5. The radiation shield 4 is thermally connected to the high temperature side stage 9 of the two-stage GM refrigerator 6 and cooled to an extremely low temperature (for example, 50K). Furthermore, the superconducting coil 1 is connected to the current leads 3a and 3b.
The intermediate temperature part 3 of the current lead in order to reduce heat penetration into the
1 is brought into thermal contact with the radiation shield 4 and cooled by the high temperature side stage 9 of the two-stage GM refrigerator 6, whereby heat is prevented from entering the superconducting coil 1 by direct conduction from room temperature. The current lead 3a on the lower temperature side than the intermediate temperature part 31 is composed of a high temperature superconductor having a small thermal conductivity and not generating Joule heat.

However, since it is impossible to make the heat intrusion into the superconducting coil 1 zero, this heat intrusion must be removed by the two-stage GM refrigerator 6. If two-stage G
When some trouble occurs in the M refrigerator 6 and the refrigerating capacity is deteriorated, heat intrusion into the superconducting coil 1 increases, and the temperature of the superconducting coil 1 rises. Further, the superconducting state is changed to the normal conducting state. In order to operate the superconducting magnet with good performance and stably for a long period of time, it is essential to improve the performance and long-term reliability of the two-stage GM refrigerator 6.

FIG. 23 is a block diagram showing a two-stage GM refrigerator 6 used in a conventional superconducting magnet. In the figure, 51 is a cylinder in which two stages of pipes whose diameters are successively reduced are coaxially connected and integrated, 52 is a first stage displacer slidably arranged in the first stage of the cylinder 51, and 53 is a cylinder 51. The second stage displacer, which is slidably disposed in the second stage of the first stage displacer 52, is connected to the first stage and the second stage displacer 52, 53 by universal joints (not shown). It has an integrated configuration. 54, 55
Are the first and second stage seals arranged to prevent the helium gas from leaking between the first and second stage displacers 52 and 53 and the respective stages of the cylinder 51, and 56 and 57 are cylinders. A first-stage expansion space, a second-stage expansion space, which is a space formed between the end surface of each stage of 51 and the first-stage and second-stage displacers 52, 53, and 58 is the first-stage displacer 5.
2 is a first-stage regenerator using copper wire mesh and lead balls as a regenerator material, 59 is a material having a composition of Ho-Er-Ru which is a kind of magnetic regenerator material as a regenerator material in the second-stage displacer 53 It is a second-stage regenerator using. Further, 7 is a compressor for compressing helium gas in the direction of the arrow, and 8 and 9 are a low temperature side stage and a high temperature side stage which are respectively arranged on the outer peripheral surface of the low temperature end of each stage of the cylinder 51. Further, 60 is an intake valve, which controls the timing of supplying high-pressure gas from the compressor 7 to the two-stage GM refrigerator 6. An exhaust valve 61 controls the timing of discharging low-pressure gas from the two-stage GM refrigerator 6 to the compressor 7. Reference numeral 62 is a drive motor, and in the cylinder 51, the displacer 52, 5
3 is reciprocated, and the valves 60 and 61 are opened and closed in conjunction with this reciprocation.

The two-stage GM refrigerator 6 configured as described above operates as follows. First, the first-stage and second-stage displacers 52, 53 are at the bottom end, and the intake valve 60 is opened.
With the exhaust valve 61 closed, high-pressure helium gas compressed by the compressor 7 is supplied into the first-stage and second-stage expansion spaces 56, 57. As a result, the first-stage and second-stage expansion spaces 56, 57 are in a high pressure state.

Next, the first and second stage displacer 5
2, 53 move upward, and accordingly high-pressure helium gas is sequentially supplied to the first-stage and second-stage expansion spaces 56, 57. During this time, the intake valve 60 remains open and the exhaust valve 61 remains closed. 1 for high pressure helium gas
When passing through the second-stage and second-stage regenerators 58 and 59, they are cooled to a predetermined temperature by the regenerator material. When the first-stage and second-stage displacers 52, 53 are at the uppermost ends, the intake valve 60 is closed and the exhaust valve 61 is opened after a short delay. At this time, the high-pressure helium gas adiabatically expands to generate freezing. Further, the helium gas existing in the expansion spaces 56 and 57 in the first and second stages has low temperatures at the respective temperature levels.
Low pressure.

Next, the first and second stage displacer 5
When 2, 53 move downward, low-temperature and low-pressure helium gas passes through the second-stage and first-stage regenerators 59, 58 and is exhausted from the exhaust valve 61. At this time, the low-temperature and low-pressure helium gas is stored in the second-stage and first-stage regenerators 59, 5
After cooling the regenerator material of No. 8, it returns to the compressor 7. The exhaust valve 61 is closed and the intake valve 60 is opened in a state where the displacers 52, 53 are moved to the lowermost ends and the volumes of the first-stage and second-stage expansion spaces 56, 57 are minimized. As a result, the high-pressure helium gas compressed by the compressor 7 is supplied to the expansion spaces 56, 57,
The pressure of 57 changes from low pressure to high pressure. The above process operates as one cycle. By repeating this cycle, the temperatures of the high temperature side stage 9 and the low temperature side stage 8 are cooled to 50K and 4.2K, respectively.

A method of fixing the superconducting coil 1 in the conventional superconducting magnet will be described. FIG. 24 is a sectional view showing the fixed portion of the superconducting coil 1. In the figure, reference numeral 41 is an adjusting screw for adjusting the position of the superconducting coil 1 via the vacuum chamber 5. The superconducting coil 1 is a support member 23.
Is fixed to the vacuum chamber 5 to some extent. In this way, the tip of the adjusting screw 41 was arranged so as to be in direct contact with the superconducting coil 1, and the head of the adjusting screw 41 penetrated the vacuum chamber 5 and was located outside the vacuum chamber 5. Superconducting coil 1
When adjusting the position, adjust screw 41 on the outside of vacuum chamber 5
The head is rotated to move the adjusting screw 41 around the superconducting coil 1 to move the position of the superconducting coil 1.

In such a structure, since the adjusting screw 41 penetrates the vacuum chamber 5, it is necessary to provide a gasket or the like in order to maintain the vacuum in the vacuum chamber 5.

In general, the heat capacity of the superconducting coil 1 is larger than that of the radiation shield 4, and the two-stage G
Regarding the refrigerating capacity of the M refrigerator 6, the high temperature side stage 9 is larger than the low temperature side stage 8. Therefore, the state of the initial cooling changes as shown in FIG. FIG. 25 is a graph showing time on the horizontal axis and temperature on the vertical axis. Radiation shield 4 is 50K
Since the superconducting coil 1 is cooled to about 4.2K, the initial cooling time of the superconducting coil 1 is t2, and the initial cooling time of the radiation shield 4 is t1. in this way,
t2 becomes twice or more than t1, and the initial cooling time of the superconducting coil 1 is longer than that of the radiation shield 4.

[0013]

In the conventional superconducting magnet, since the regenerator 6 is arranged near the superconducting coil 1 as described above, the regenerator 6 is placed in the magnetic field of the superconducting coil 1. It is arranged. For this reason, the drive motor 62 of the cold storage type refrigerator 6 which is easily affected by the magnetic field cannot operate normally, and the step-out operation is performed. Therefore, a normal heat cycle cannot be realized, and the refrigerating capacity of the regenerative refrigerator 6 deteriorates. Further, if the operation is continued in the step-out state, the drive motor 62, the first and second stage seals 54, 5
There is a problem that excessive force is generated in 5 and the like, and the progress of friction and wear is accelerated so that the cold-storage refrigerator 6 cannot be stably operated for a long period of time.

Further, since the second-stage regenerator 59 is made of a magnetic regenerator material, electromagnetic force and heat are generated under the influence of the magnetic field. That is, since Ho-Er-Ru, which is a kind of magnetic regenerator material, is used as the regenerator material of the second-stage regenerator 59, it receives an electromagnetic force when there is a magnetic field gradient. When an excessive electromagnetic force is applied to the regenerator material of the second-stage regenerator 59, an excessive torque is applied to the drive motor 62, the drive motor 62 does not rotate normally, a normal heat cycle cannot be realized, and a desired refrigerating capacity is obtained. Disappear. Further, the magnetic regenerator material exhibits a magnetic hysteresis in a magnetic field to generate heat. When heat is generated, the freezing capacity obviously deteriorates. When an electromagnetic force is generated, the drive motor 62
There is also a problem that excessive force is generated in the first-stage and second-stage seals 54, 55 and the like, and the progress of friction and wear is accelerated so that the cold storage refrigerator 6 cannot be operated stably in the long term.

Further, when the cold storage type refrigerator 6 is replaced and the cold storage type refrigerator 6 is replaced, the low temperature side stage 8 of the cold storage type refrigerator 6 is disposed directly on the superconducting coil. Had to be disassembled, and there was a problem that maintenance was difficult.

Further, since the current leads 3a and 3b are arranged in the vicinity of the superconducting coil 1, they are affected by the magnetic field,
There is also a problem that the current density is reduced.

During the initial cooling, thermal stress is applied to the regenerator 6 due to the difference in the coefficient of thermal expansion of the material of the structure, and the refrigerating capacity is deteriorated due to friction and wear of the regenerator 6 and stable for a long period of time. There is also a problem that the regenerator 6 cannot be operated.

Further, during the initial cooling, there is a problem that the superconducting coil 1 is subjected to thermal stress due to the difference in the coefficient of thermal expansion of the material of the structure, and the performance of the superconducting coil 1 is deteriorated.

Further, since the superconducting coil 1 and the regenerator 6 are thermally connected to each other in only one place, a temperature distribution is generated in the superconducting coil 1 and the stability of the superconducting coil is deteriorated. There was also.

Further, since the magnetic field distribution by the superconducting coil 1 is adjusted, it is difficult to adjust the relative position with respect to the magnetic shield while holding the vacuum.

In general, the heat capacity of the superconducting coil 1 is larger than that of the radiation shield 4, and the refrigerating capacity of the regenerator 6 is higher in the high temperature side stage 9 than in the low temperature side stage 8. Therefore, there is also a problem that the initial cooling time of the superconducting coil 1 is longer than that of the radiation shield 4.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to improve the performance and reliability of a superconducting coil provided with a cold storage type refrigerator. Furthermore, another object is to obtain a superconducting magnet having a structure that can be easily maintained.

[0023]

A superconducting magnet according to the invention of claim 1 is a regenerator having a superconducting coil, a radiation shield enclosing the superconducting coil, a vacuum chamber enclosing the radiation shield, and a magnetic regenerator. In a provided superconducting magnet, a magnetic shield for shielding a magnetic field generated by the superconducting coil is provided, and the cold storage refrigerator is arranged on the opposite side of the magnetic shield from the superconducting coil.

The superconducting magnet according to a second aspect of the present invention is, in addition to the first aspect of the present invention, the regenerator has a low temperature side stage and a high temperature side stage, and the superconducting coil has a low temperature side stage and a radiation shield. Is cooled by a high temperature side stage, and is provided with a conductive member for thermally connecting the superconducting coil and the low temperature side stage.

A superconducting magnet according to a third aspect of the present invention is a superconducting coil unit comprising a superconducting coil, a first radiation shield surrounding the superconducting coil, and a first vacuum chamber surrounding the first radiation shield, and a second superconducting coil unit. A radiation shield, a cold storage stage for cooling the superconducting coil at a low temperature side, a regenerator for cooling the radiation shield at a high temperature side, and a refrigerator unit composed of a second vacuum tank surrounding the second radiation shield, and a superconducting coil and a low temperature stage. Is provided, the superconducting coil unit and the refrigerator unit can be separated, the first and second radiation shields are thermally connected, and the first vacuum tank and the second vacuum tank are airtightly connected. It was done.

Further, in the superconducting magnet according to the invention of claim 4, in addition to the invention of claim 3, the current lead for supplying a current to the superconducting coil is composed of a high temperature side, a low temperature side and a connecting portion, and The low temperature side current lead is arranged in the refrigerator unit, and the middle temperature portion thereof is thermally connected to the second radiation shield.

Further, in the superconducting magnet according to the invention of claim 5, in addition to the invention of claim 3 or 4, the connecting portions of the first vacuum chamber and the second vacuum chamber are flanged to each other and hermetically connected. It is a thing.

The superconducting magnet according to the invention of claim 6 is the one according to any one of claims 2 to 5, in which a heat exchanger for initially cooling the superconducting coil is provided in the conductive member.

In the superconducting magnet according to the invention of claim 7, the superconducting coil, the radiation shield surrounding the superconducting coil, the vacuum chamber surrounding the radiation shield, the superconducting coil at the low temperature side stage, and the radiation shield at the high temperature side stage are cooled. And a conductive member that is at least partially formed of a flexible body and thermally connects the superconducting coil and the low temperature side stage.

The superconducting magnet according to an eighth aspect of the present invention is the superconducting magnet according to the seventh aspect, wherein the connecting portion of the conductive member on the superconducting coil side is composed of a plurality of flexible members.

According to a ninth aspect of the present invention, there is provided a superconducting magnet, a superconducting coil, a superconducting coil fixed thereto, a vacuum chamber surrounding the superconducting coil, a magnetic shield surrounding the vacuum chamber, and a relative relation between the magnetic shield and the vacuum chamber. It is provided with an adjusting mechanism capable of adjusting the relative position between the magnetic shield and the superconducting coil by adjusting the position.

A superconducting magnet according to a tenth aspect of the present invention includes a superconducting coil, a radiation shield surrounding the superconducting coil, a superconducting coil fixed via the radiation shield, and a vacuum chamber surrounding the radiation shield. And a magnetic shield and an adjusting mechanism capable of adjusting the relative position between the magnetic shield and the superconducting coil by adjusting the relative position between the magnetic shield and the vacuum chamber.

The superconducting magnet according to the invention of claim 11 is a superconducting coil, a radiation shield surrounding the superconducting coil, a vacuum chamber surrounding the radiation shield, the superconducting coil at a low temperature side stage, and the radiation shield at a high temperature side stage. A regenerative refrigerator, a heat transport pipe for transporting heat between the high temperature side stage and the low temperature side stage, a filling means for filling the heat transport pipe with a cryogenic refrigerant, and a decompression means for decompressing the cryogenic refrigerant of the heat transport pipe. Be prepared.

The superconducting magnet according to a twelfth aspect of the present invention is the superconducting magnet according to the eleventh aspect of the present invention, in which a heat transport pipe having a toroidal cross section is provided between the high temperature side stage and the low temperature side stage of the regenerator. Is arranged so as to surround the heat exchanger and heat is transferred between the high temperature side stage and the low temperature side stage.

[0035]

In the superconducting magnet according to the first aspect of the present invention, the regenerator is arranged on the side opposite to the superconducting coil with respect to the magnetic shield. Therefore, even if the superconducting coil generates a strong magnetic field, the regenerator is a regenerator. The machine is outside the magnetic field and no magnetic field is applied. Therefore, the drive motor of the cold storage refrigerator, which is easily affected by the magnetic field, operates normally. Further, since the magnetic field is not applied to the regenerator made of the magnetic regenerator, electromagnetic force or heat is not generated in the regenerator.

Further, in the superconducting magnet according to claim 2 of the present invention, the regenerator type refrigerator is arranged on the side opposite to the superconducting coil with respect to the magnetic shield, and the superconducting coil and the regenerator type refrigerator are placed on the low temperature side. The stages are thermally connected. Therefore, even if the superconducting coil generates a strong magnetic field, no magnetic field is applied to the cold storage refrigerator.

In the superconducting magnet according to claim 3 of the present invention, the superconducting coil unit and the refrigerator unit are separable from each other. Therefore, when a failure occurs in the regenerator, the refrigerator unit and the superconducting coil unit. Can be disassembled and only the refrigerator unit is disassembled to replace the cold storage refrigerator, or another refrigerator unit can be replaced to take measures against a failure. Furthermore, a conductive member thermally connected to the low temperature side stage of the cold storage refrigerator and the superconducting coil is provided, and the cold storage refrigerator is provided separately from the superconducting coil.

In the superconducting magnet according to claim 4 of the present invention, the current lead is arranged in the refrigerator unit,
The current leads are less affected by the magnetic field of the superconducting coil. Therefore, it is possible to prevent the current density of the current lead from decreasing.

In the superconducting magnet according to claim 5 of the present invention, the first vacuum chamber of the superconducting coil unit and the second vacuum chamber of the refrigerator unit have a flange structure with each other, so that the first vacuum chamber and the first vacuum chamber The two vacuum chambers can be easily separated. When maintenance of the regenerator is necessary, the second vacuum tank in which the regenerator is installed is cut off from the first vacuum tank, and the refrigerator unit is separated for maintenance.

In the superconducting magnet according to claim 6 of the present invention, a heat exchanger is thermally connected to the conductive member, the conductive member is cooled by the heat exchanger, and the superconducting coil is initially cooled from the conductive member. You can Therefore, it can be expected that the superconducting coil is cooled by the regenerator or the heat exchanger. Since this heat exchanger is provided on the conductive member, the structure of the superconducting coil does not become complicated.

Further, in the superconducting magnet according to claim 7 of the present invention, since at least a part of the conductive member is made of a flexible body, the difference in the coefficient of thermal expansion of the structure during the initial cooling may be varied. Therefore, the regenerative refrigerator does not receive thermal stress. Similarly, the superconducting coil is not subjected to thermal stress, and the thermal stress does not deteriorate the performance of the superconducting coil.

Further, in the superconducting magnet according to claim 8 of the present invention, since the plurality of flexible bodies are thermally connected at the connecting portion between the conducting member and the one or more superconducting coils,
The temperature gradient does not become large with one or a plurality of superconducting coils, and the deterioration of the performance of the superconducting coil due to the temperature gradient can be prevented. Further, at the time of initial cooling, the difference in the coefficient of thermal expansion of the structure is absorbed by the flexible body, and thermal stress is not applied to the regenerator or superconducting coil.

Further, in the superconducting magnet according to claim 9 of the present invention, when the superconducting coil is fixed to the vacuum chamber and the relative position of the magnetic shield and the superconducting coil is adjusted, the relative position of the magnetic shield and the vacuum chamber is adjusted by the adjusting mechanism. Adjust. Therefore, no special structure is required to maintain the vacuum.

In the superconducting magnet according to the tenth aspect of the present invention, the superconducting coil is fixed to the radiation shield, and the vacuum layer is provided so as to surround the radiation shield. When adjusting the relative position of the magnetic shield and the superconducting coil, the relative position of the magnetic shield and the vacuum chamber is adjusted by the adjusting mechanism. Therefore, no special structure is required to maintain the vacuum.

Further, in the superconducting magnet according to claim 11 of the present invention, a heat transport pipe for transporting heat between the high temperature side stage and the low temperature side stage of the regenerator is provided, and the heat transport pipe is cryogenically cooled by the filling means. Fill with refrigerant. During initial cooling, when the temperature of the high temperature side stage is lower than the temperature of the low temperature side stage, the temperature of the cryogenic refrigerant near the high temperature side stage in the heat transport pipe becomes lower than the temperature of the cryogenic refrigerant near the low temperature side stage and the density growing. Therefore, the refrigerating capacity of the high temperature side stage of the cold storage type refrigerator can be transported to the low temperature side stage by the heat transport pipe. Since the refrigerating capacity of the high temperature side stage is partially distributed to the low temperature side stage, the initial cooling time of the superconducting coil can be shortened. Conversely, when the temperature of the high temperature side becomes higher than the temperature of the low temperature side, the pressure reducing means reduces the pressure of the cryogenic refrigerant in the heat transport pipe to weaken the thermal connection between the high temperature side and the low temperature side, Eliminates heat transfer from the stage to the cold side.

Further, in the superconducting magnet according to the twelfth aspect of the present invention, since the heat transport pipe having a donut-shaped cross section is arranged so as to surround the cylinder of the regenerator, the heat convection pipe and the superconducting coil are formed. The heat transfer area increases,
The temperature of the superconducting coil can be made uniform and cooled.

[0047]

【Example】

Example 1. Hereinafter, as the superconducting magnet according to the first embodiment of the present invention, for example, a superconducting magnet for a synchrotron radiation device will be described. FIG. 1 is a sectional view showing a superconducting magnet according to the first embodiment. In the figure, FIG.
Also, the same or corresponding parts as those of the conventional superconducting magnet shown in FIG. 23 are designated by the same reference numerals, and the description thereof will be omitted.
In the figure, 13 is a current lead for supplying a current to the superconducting coil 1, 14 is a high temperature side radiation shield arranged so as to surround the radiation shield 4, and 15 is a persistent current for realizing a mode of a persistent current flowing in the superconducting coil 1. Switch, 22
Is a two-stage GM refrigerator for cooling the shield.
Then, the high temperature side radiation shield 14 is cooled, and the low temperature side stage cools the radiation shield 4 to maintain the temperatures at 80K and 20K, respectively. 20 is a helium tank which holds liquid helium and which houses the superconducting coil 1, 21 is liquid helium which is a cryogenic refrigerant which holds the superconducting coil 1 in a superconducting state, 23 is the radiation shield 4 and the high temperature side radiation shield 1
A support member for holding the helium tank 20 in the vacuum tank 5 via 4, a beam chamber 24, and a beam chamber 24.
Is a high temperature side radiation shield of the beam chamber, and 26 is a beam chamber radiation shield arranged so as to surround the high temperature side radiation shield 25 of the beam chamber. Although not shown, the high temperature side radiation shield 25 of the beam chamber is thermally connected to the high temperature side radiation shield 14, and the beam chamber radiation shield 26 is thermally connected to the radiation shield 4. Reference numeral 27 is a regenerator, for example, a helium liquefying GM refrigerator, and its configuration is the same as that of the two-stage GM refrigerator 6 shown in FIG. The helium liquefying GM refrigerator 27 liquefies the evaporated helium of the liquid helium 21 again. A magnetic shield 30 is made of, for example, iron. The radiation shields 4, 14, 25, 26 are made of copper, for example.

In the superconducting magnet according to the first embodiment constructed as described above, the superconducting coil 1 is brought to an extremely low temperature (for example, 4.2 by the liquid helium 21 in the helium tank 20).
It is cooled to K) and becomes superconducting. In this state, an exciting current is supplied from an external power source (not shown) for the superconducting coil to the superconducting coil 1 via the current lead 13 to generate a predetermined magnetic field. Then, in the steady state, a current is made to flow through the superconducting coil 1 through the permanent current switch 15 to cut off the electrical contact with the external superconducting coil power source. Therefore, the superconducting coil 1 is in the permanent current mode,
A predetermined magnetic field can be generated with the external power supply for the superconducting coil disconnected. On the other hand, the beam chamber 2
The inside of 4 is evacuated to a high vacuum, and the electrons accelerated to high energy are guided in this. The trajectory of the electron motion is in the beam chamber 2
It is regulated by a magnetic field generated by a pair of superconducting coils 1 arranged so as to sandwich 4 between them.

In the helium liquefying GM refrigerator 27, for example, a material having a composition of Ho-Er-Ru is used as a regenerator material for the first-stage regenerator 58 such as a copper mesh and lead balls and a regenerator material for the second-stage regenerator 59. To use. The liquid helium 21 vaporized by the heat entering the superconducting coil 1 is liquefied again on the low temperature side stage 8. Second stage regenerator 59 of GM refrigerator 27 for liquefying helium
A magnetic regenerator is used as the regenerator, and it receives electromagnetic force when there is a magnetic field gradient. When an excessive electromagnetic force is applied to the regenerator material of the second stage regenerator 59, an excessive torque is applied to the drive motor 62. Due to this excessive torque, the drive motor 62
If does not rotate normally, the normal heat cycle cannot be realized and the required refrigerating capacity cannot be obtained. Also,
The drive motor 62 itself also does not rotate normally in a strong magnetic field, and the desired refrigerating capacity cannot be obtained.

On the other hand, in the first embodiment, the magnetic shield 3
0 is provided to shield the magnetic field generated in the superconducting coil 1 from leaking to the outside. GM for helium liquefaction
The refrigerator 27 is arranged on the side opposite to the superconducting coil 1 with respect to the magnetic shield 30, that is, outside the magnetic shield 30. Therefore, even if the superconducting coil 1 generates a strong magnetic field, the helium liquefying GM refrigerator 27 is outside the magnetic field and no magnetic field is applied. Therefore, the drive motor 62 of the helium liquefying GM refrigerator 27 that is easily affected by the magnetic field operates normally. Further, since the magnetic field is not applied to the regenerator composed of the magnetic regenerator, it is possible to prevent the regenerator from generating electromagnetic force or heat.

Example 2. Hereinafter, as a superconducting magnet according to a second embodiment of the present invention, for example, a superconducting magnet for a levitation railway will be described. FIG. 2 is a sectional view showing a superconducting magnet according to the second embodiment. In the figure, 2
8 is a single-stage GM refrigerator for shield cooling, 29 is a cooling stage of the single-stage GM refrigerator for shield cooling 28, 32 is a supply pipe for supplying the liquid helium 21 to the superconducting coil 1, 33
Is a recovery pipe provided to open the gas phase portion in the upper part of the helium tank 20 for recovering the vaporized gas of the liquid helium 21, and 34 is a cooling pipe for cooling the current lead 13.

In the superconducting magnet according to the second embodiment configured as described above, the radiation shield 4 is in thermal contact with the cooling stage 29 of the single-stage GM refrigerator 28 for shield cooling and is cooled to about 70K. There is. Helium tank 20
The liquid helium 21 therein is vaporized by heat entry and becomes an evaporated gas, cooled by the helium liquefying GM refrigerator 27, and liquefied again.

In the second embodiment, as in the first embodiment, the magnetic shield 30 is provided to shield the magnetic field generated in the superconducting coil 1 from leaking to the outside. The helium liquefying GM refrigerator 27 is arranged on the side opposite to the superconducting coil 1 with respect to the magnetic shield 30, that is, outside the magnetic shield 30. Therefore, even if the superconducting coil 1 generates a strong magnetic field, the helium liquefying GM refrigerator 27 is outside the magnetic field and no magnetic field is applied. For this reason, the drive motor 6 of the helium liquefying GM refrigerator 27 that is easily affected by the magnetic field
2 works normally. Further, since the magnetic field is not applied to the regenerator composed of the magnetic regenerator, it is possible to prevent the regenerator from generating electromagnetic force or heat.

Example 3. Third Embodiment FIG. 3 is a sectional view showing a superconducting magnet according to a third embodiment of the present invention. The third embodiment shows an example in which the magnetic shield is disposed at a different position from the second embodiment. In the third embodiment, the magnetic shield 30 is arranged in the vacuum chamber 5, so that the same effect as that of the second embodiment can be expected. Also in this embodiment, the helium liquefying GM refrigerator 27 is arranged on the side opposite to the superconducting coil 1 with respect to the magnetic shield 30, that is, outside the magnetic shield 30. Therefore, even if the superconducting coil 1 generates a strong magnetic field, the helium liquefying GM refrigerator 27 is outside the magnetic field and no magnetic field is applied. Therefore, the drive motor 62 of the helium liquefying GM refrigerator 27 that is easily affected by the magnetic field operates normally. Further, since the magnetic field is not applied to the regenerator composed of the magnetic regenerator, it is possible to prevent the regenerator from generating electromagnetic force or heat. Further, since the magnetic shield 30 is arranged inside the vacuum chamber 5, space can be saved.

Embodiment 4 FIG. 4 is a sectional view showing a superconducting magnet according to Embodiment 4 of the present invention. In the figure, 35 is a conductive member that thermally connects the low temperature side stage 8 of the two-stage GM refrigerator 6 and the superconducting coil 1, and 36 is a flexible body that constitutes a part of the conductive member 35. The connecting portion is flexibly connected. Here, the conductive member 35 is made of a good heat conductive material such as copper or aluminum. The flexible body 36 is made of a material having good thermal conductivity such as copper and has a structure such as a braided wire or a spring. The high temperature side stage 9 of the two-stage GM refrigerator 6 is thermally connected to the radiation shield 4 and cools the radiation shield 4.
The superconducting coil 1 is fixed to the radiation shield 4 by the support member 23. Alternatively, the superconducting coil 1 may be fixed to the vacuum chamber 5 by using the supporting member 23. The support member 23 is made of, for example, a heat insulator such as glass epoxy (GFRP).

In the conventional superconducting magnet constituted by directly connecting the conductive member 35 to the superconducting coil 1 and the two-stage GM refrigerator 6, when the superconducting coil 1 and the radiation shield 4 are cooled, the two-stage GM refrigerator. 6, support member 23,
Thermal stress is generated due to the difference in thermal expansion coefficient between the radiation shield 4, the superconducting coil 1, the conductive member 35, and the like. This thermal stress is
The superconducting coil 1, the radiation shield 4, the two-stage GM refrigerator 6, the support member 23, and the conductive member 35 are mechanical loads, respectively. This mechanical load causes deterioration of the refrigerating capacity of the two-stage GM refrigerator 6, deterioration of the performance of the superconducting coil 1, fatigue of constituent materials and deterioration of various characteristics. Therefore, in this embodiment, as shown in FIG. 4, a part of the conductive member 35 that connects the superconducting coil 1 and the low temperature side stage 8 of the two-stage GM refrigerator 6 is configured by a flexible body 36. Therefore, especially during initial cooling, the mechanical load applied between the superconducting coil 1, the conductive member 35, and the low temperature side stage of the two-stage GM refrigerator 6 by absorbing the difference in the coefficient of thermal expansion of the structure with the flexible body. Can be relaxed.

Example 5. 5 is a sectional view showing a superconducting magnet according to Embodiment 5 of the present invention. In the figure, 4a is a first radiation shield that surrounds the superconducting coil 1. A part of the first radiation shield 4a is a magnetic shield 3a.
0 surrounds. The magnetic shield 30 is provided with an opening. The first radiation shield 4a is pulled out from the opening of the magnetic shield 30, and the first radiation shield 4a is moved to the second radiation shield 4a.
It is thermally connected to the radiation shield 4b. The second radiation shield 4b is thermally connected to the high temperature side stage 9 of the two-stage GM refrigerator 6. Also, 5a is a first vacuum chamber,
Surrounding the radiation shield 4a and the magnetic shield 30, 5b
Encloses the second radiation shield 4b with a second vacuum chamber. First
A gasket (not shown) for the vacuum chamber 5a and the second vacuum chamber 5b
Connect airtightly with. The superconducting coil unit 10, the first radiation shield 4a, and the first vacuum chamber 5a
1, two-stage GM refrigerator 6, second radiation shield 4
The refrigerator unit 102 is configured by b and the second vacuum tank 5b.

The connecting portion of the conductive member 35 with the superconducting coil 1 is made of a flexible body 36, and the superconducting coil 1
Thermal connection with. Further, the conductive member 35 is provided in the first radiation shield 4 drawn from the opening of the magnetic shield 30.
It is drawn to the outside of the magnetic shield 30 through the inside of a. The conductive member 35 drawn out from the opening of the magnetic shield 30 is thermally connected to the low temperature side stage 8 of the two-stage GM refrigerator 6.

In this embodiment, a part of the conductive member 35 is constituted by the flexible member 36, and like the fourth embodiment, the low temperature side stage 8 of the two-stage GM refrigerator 6, the conductive member 35, and the superconducting coil. The flexible body 36 relieves the mechanical load caused by thermal stress between the first and the like. Therefore, in the two-stage GM refrigerator 6 and the superconducting coil 1, performance deterioration due to thermal stress can be prevented. Further, in this embodiment, the superconducting coil 1 and the low temperature side stage 8 of the two-stage GM refrigerator 6 are thermally connected by the conductive member 35. The two-stage GM refrigerator 6 is arranged on the side opposite to the superconducting coil 1 with respect to the magnetic shield 30. Therefore, the magnetic field generated by the superconducting coil 1 is 2
It is possible to prevent deterioration of the refrigerating capacity without affecting the stage GM refrigerator 6. Further, since the vacuum chamber 5a and the vacuum chamber 5b are airtightly connected by a gasket, the superconducting coil unit 101 and the refrigerator unit 102 can be separated. Since the superconducting coil 1 has no moving part, it can continue to flow the exciting current for a long period of time, but the two-stage GM refrigerator 6 has a moving part and therefore requires periodic maintenance. At this time, if the refrigerator unit 102 is separated from the superconducting coil unit 101 and another refrigerator unit 102 having the already-maintained two-stage GM refrigerator 6 is connected to the superconducting coil unit 101, the maintenance time is shortened, Maintenance itself can also be simplified.

Example 6. 6 is a sectional view showing a superconducting magnet according to Embodiment 6 of the present invention. In the figure, the superconducting coil 1 is conductively cooled by the low temperature side stage 8 of the two-stage GM refrigerator 6 via the conductive member 35. At this time, the superconducting coil side connection portion of the conductive member 35 is composed of a plurality of flexible bodies 36, in this embodiment two flexible bodies 36, and the flexible body 36 is used at a plurality of locations of the superconducting coil 1. Cooling. When one portion of the superconducting coil 1 is thermally connected by the flexible body 36 and cooled, the superconducting coil 1 is cooled from the portion at which the one portion is thermally connected. For this reason, the temperature at the point apart from the point where the flexible body 36 is thermally connected is higher than the temperature at the point where the flexible body 36 is thermally connected. On the other hand, in this embodiment, the flexible body 36 is provided at a plurality of locations on the superconducting coil 1.
When it is thermally connected to and cooled, the temperature gradient of the superconducting coil 1 becomes small. Since the temperature gradient of the superconducting coil 1 becomes small, the stability of the superconducting magnet can be improved. Further, at the time of initial cooling, the difference in the coefficient of thermal expansion of the structure is absorbed by the flexible body 36, and thermal stress is not applied to the two-stage GM refrigerator 6 and the superconducting coil 1.

The connecting portion between the flexible member 36 and the superconducting coil 1 is not limited to two places, and if it is formed at a plurality of two or more places, the effect is further enhanced.

Example 7. 7 is a sectional view showing a superconducting magnet according to Embodiment 7 of the present invention. As shown in the figure, in this embodiment, two superconducting coils 1 are provided, and each of them is configured to be connected to the flexible body 36. The two superconducting coils 1 are conductively cooled by the low temperature side stage 8 of the two-stage GM refrigerator 6 via the conductive member 35. When the flexible body 36 is connected to each of the two superconducting coils 1 to cool them, the two superconducting coils 1 are simultaneously cooled, so that the temperature difference between the two superconducting coils 1 becomes small. Since the temperature gradient of the superconducting coil 1 becomes small, the stability of the superconducting magnet can be improved.

The flexible body 36 and the superconducting coil 1 are not limited to two locations, respectively. As shown in the sixth embodiment, a plurality of flexible bodies 36 are connected to each superconducting coil 1. May be. The effect will be even greater if it is composed of two or more locations. Also,
The number of superconducting coils 1 is not limited to two.

Example 8. 8 is a sectional view showing a superconducting magnet according to Embodiment 8 of the present invention. In the figure, 37 is a refrigerator side flexible body that thermally connects the low temperature side stage 8 of the two-stage GM refrigerator 6 and the conductive member 35, 38 is a flange that airtightly connects the vacuum tank 5a and the vacuum tank 5b, Three
a, 3b, 3c are current leads, and 3a is, for example, Y-
Ba-Cu-O, Bi-Sr-Ca-Cu-O, Tl-Ba-Ca-Cu-O
, La-Ba-Cu-O, etc., a low-temperature side current lead composed of a high-temperature superconductor, 3b is a high-temperature side current lead composed of, for example, a copper pipe, 3c is a metal-based superconducting wire relatively resistant to a magnetic field. Then, it is connected to the superconducting coil 1 by a current lead of a connecting portion made of, for example, NbTi, Nb ₃ Sn or the like. Reference numeral 31 is an intermediate temperature part composed of sapphire, diamond, mylar film, Kapton film, etc., which is electrically connected to the current lead 3b on the high temperature side and the second radiation shield 4b and electrically insulated. The intermediate temperature section 31 is provided to reduce heat intrusion from the high temperature side current lead 3b into the superconducting coil 1. The refrigerator-side flexible body 37 is made of a material having a good thermal conductivity such as copper, and has a structure such as a braided wire or a spring.

In the superconducting magnet configured as described above, since the low temperature side stage 8 of the two-stage GM refrigerator 6 and the conductive member 35 are connected by the flexible body 37, the superconducting coils 1 and 2 are initially cooled. Stage GM refrigerator 6, support member 2
It is possible to relieve the thermal stress caused by the difference in the coefficient of thermal expansion of the conductive member 35. Further, by transmitting the refrigerating capacity of the two-stage GM refrigerator 6 to the superconducting coil 1 by heat conduction by the conductive member 35, the two-stage GM refrigerator 6 can be arranged in a place where the magnetic field of the superconducting coil 1 is less affected. it can. Therefore, it is possible to prevent the drive motor 62 of the two-stage GM refrigerator 6 from being affected by the magnetic field, and prevent an excessive electromagnetic force from being applied to the second-stage regenerator 59 of the two-stage GM refrigerator 6. It is possible to avoid a situation where the refrigerating capacity is deteriorated or the reliability is lowered.

Further, in this embodiment, the high temperature superconductor is used for the current lead 3a on the low temperature side, and the high temperature superconductor has a characteristic that the smaller the influence of the magnetic field, the more the current flows. For this reason, it is arranged in the refrigerator unit 102 and is electrically connected to the superconducting coil 1 via the current leads 3b and 3c. According to this structure, the current lead 3a on the low temperature side can be arranged at a position apart from the superconducting coil 1, and the performance is improved. Also, the vacuum chamber 5a
Since the vacuum chamber 5b and the vacuum chamber 5b are hermetically connected by the flange 38, the superconducting coil unit 101 and the refrigerator unit 10 are
2 can be easily separated. Therefore, the maintenance time can be shortened and the maintenance itself can be simplified.

Example 9. FIG. 9 is a sectional view showing a klystron superconducting magnet according to Embodiment 9 of the present invention. In the figure, 30 is a magnetic shield arranged so as to surround the first vacuum chamber 5a. Since the two-stage GM refrigerator 6 is arranged on the side opposite to the superconducting coil 1 with respect to the magnetic shield 30, the magnetic field of the superconducting coil 1 is a two-stage GM.
It hardly affects the refrigerator 6. Therefore, even if the superconducting coil 1 generates a strong magnetic field, the refrigerating capacity and reliability of the two-stage GM refrigerator 6 are not affected. Further, a high temperature superconductor is used for the current lead 3a on the low temperature side, and the high temperature superconductor has a characteristic that a current flows more when the influence of the magnetic field is smaller. Therefore, in this embodiment, the low temperature side current lead 3a is connected to the magnetic shield 30 by the superconducting coil 1.
It is disposed on the opposite side to and is thermally connected to the middle temperature portion of the current lead and the second radiation shield 4b. With this configuration, the performance is improved. In the superconducting magnet of this embodiment, electrons move in the hollow portion of the vacuum chamber 4a. Since the magnetic field generated by the superconducting coil 1 exists in this hollow portion, the movement of electrons is restricted.

Example 10. 10 is a sectional view showing a superconducting magnet according to Embodiment 10 of the present invention. This embodiment has the same configuration as that of the ninth embodiment, except that the installation direction of the superconducting coil 1 is such that the direction of the magnetic field is horizontal. The conductive member 35 is connected to the end surface of the superconducting coil 1, the first radiation shield 4a and the vacuum chamber 5a are extended from the end surface, and the second radiation shield 4b and the second radiation shield 4b.
It was configured to be connected to each of the vacuum chambers 5b.

With such a structure, a superconducting magnet capable of generating a magnetic field in the horizontal direction can be obtained, and as in the ninth embodiment, it has excellent effects in terms of performance and reliability and simplifies maintenance.

Example 11. 11 is a sectional view showing a superconducting magnet according to Embodiment 11 of the present invention. The difference from Example 10 is that the installation direction of the superconducting coil 1 is such that the direction of the magnetic field is another horizontal direction. That is, the superconducting coil 1, the first radiation shield 4a, and the vacuum chamber 5a are each formed in a cylindrical shape. The conductive member 35 is connected to the cylindrical portion of the superconducting coil 1, and the first radiation shield 4a and the vacuum chamber 5a are connected to each other. The second radiation shield 4b and the second vacuum chamber 5b are connected to each other by extending from a part of the circumference.

By installing the superconducting coil 1 in this way, a superconducting magnet capable of generating a magnetic field in the horizontal direction can be obtained, which is excellent in performance and reliability, as in the tenth embodiment.
This has the effect of simplifying maintenance. Furthermore, there is no obstacle on the end surface of the magnetic shield 30, and it becomes easy to use the superconducting magnet.

Example 12 12 is a sectional view showing a superconducting magnet according to Embodiment 12 of the present invention. 40
Is a heat exchanger, for example, an initial cooling pipe made of a stainless steel pipe, which is introduced from the vacuum chamber 5b of the refrigerator unit 102 and arranged so as to be in thermal contact with the conductive member 35, and its tip is It is formed in a U shape. 13 is an enlarged view of the conductive member 35 and the initial cooling pipe 40. FIG. 13 (a) is a top view and FIG. 13 (b) is a side view. The initial cooling pipe 40 and the conductive member 35 are thermally connected to each other by, for example, soldering, brazing, or bonding with an adhesive.

In the superconducting magnet thus constructed, for example, liquid nitrogen is introduced as a cryogenic refrigerant into the initial cooling pipe 40 from outside the vacuum chamber 5b. The conductive member 3 thermally connected to the initial cooling pipe 40 by the introduced liquid nitrogen.
Cool 5 The liquid nitrogen that has cooled the conductive member 35 is folded back at the tip of the conductive member 35 on the side of the superconducting coil 1 and exhausted to the outside of the vacuum chamber 5b. Since the conductive member 35 cooled with liquid nitrogen is thermally connected to the superconducting coil 1 via the flexible body 36, the cold of the conductive member 35 is conducted to the superconducting coil 1 and the superconducting coil 1 is cooled.

At the time of initial cooling, cooling the superconducting coil 1 only by the two-stage GM refrigerator 6 takes too much time because of the large heat capacity of the superconducting coil 1. On the other hand, in this embodiment, since the superconducting coil 1 is cooled by the initial cooling pipe 40, 2
Rather than cooling the superconducting coil 1 only with the stage GM refrigerator 6,
The initial cooling time is significantly reduced. Although liquid nitrogen was used as the cryogenic refrigerant, other cryogenic refrigerants such as liquid helium are also applicable.

Example 13 14 is a sectional view showing the vicinity of a superconducting coil according to Embodiment 13 of the present invention. In the figure, reference numeral 41 denotes an adjusting mechanism capable of adjusting the relative positions of the superconducting coil 1 and the magnetic shield 30 via the vacuum chamber 5, for example, eight adjusting screws provided around the superconducting coil 1. The superconducting coil 1 is fixed to the vacuum chamber 5 by a supporting member 23.

In the superconducting magnet configured as described above, when adjusting the relative positions of the magnetic shield 30 and the superconducting coil 1, the adjusting screw 41 around the screw is loosened or tightened. The vacuum chamber 5 moves accordingly. When the vacuum chamber 5 is moved, the superconducting coil 1 fixed in the vacuum chamber 5 also moves. If a jig (not shown) for measuring the distance between the vacuum chamber 5 and the magnetic shield 30 is provided, the relative distance between the magnetic shield 30 and the vacuum chamber 5 when the adjusting screw 41 is turned can be known, and then the magnetic field can be obtained. The relative position between the shield 30 and the superconducting coil 1 can be adjusted.

As described above, since the relative positions of the superconducting coil 1 and the magnetic shield 30 can be adjusted without breaking the vacuum of the vacuum chamber 5, the magnetic field distribution can be easily adjusted.

Example 14. FIG. 15 is a sectional view showing the vicinity of the superconducting coil according to Embodiment 14 of the present invention. The adjusting screws 41 are adjusting mechanisms capable of adjusting the relative positions of the superconducting coil 1 and the magnetic shield 30 via the vacuum chamber 5 and the radiation shield 4, and, like the thirteenth embodiment, eight adjusting screws 41 are provided around the superconducting coil 1. .

In the superconducting magnet configured as described above, when adjusting the relative position between the magnetic shield 30 and the superconducting coil 1, the adjusting screw 41 is loosened or tightened. The vacuum chamber 5 moves accordingly. When the vacuum chamber 5 moves, the radiation shield 4 fixed to the vacuum chamber 5 moves accordingly, and when the radiation shield 4 moves, the superconducting coil 1 fixed to the radiation shield 4 also moves. Vacuum tank 5
A jig (not shown) for measuring the distance between the magnetic shield 30 and the magnetic shield 30.
If the adjusting screw 41 is turned, the relative distance between the magnetic shield 30 and the vacuum chamber 5 can be known, and then the relative position between the magnetic shield 30 and the superconducting coil 1 can be adjusted.

As described above, since the relative positions of the superconducting coil 1 and the magnetic shield 30 can be adjusted without breaking the vacuum of the vacuum chamber 5, the magnetic field distribution can be easily adjusted. Also,
The support member for fixing the radiation shield 4 is used as the superconducting coil 1
The supporting member 23 for fixing can also serve as the fixing member, the number of supporting members can be reduced as a whole, and the structure can be simplified as compared with the thirteenth embodiment.

Although the adjusting screw is used as the adjusting mechanism in the thirteenth and fourteenth embodiments, the present invention is not limited to this.
For example, a pressure adjusting mechanism may be used to adjust the distance between the magnetic shield 30 and the superconducting coil 1 by pressurizing and depressurizing.

Example 15 16 is a sectional view showing a superconducting magnet according to Embodiment 15 of the present invention. In the figure, 42 is a heat transport pipe for transporting heat between the low temperature side stage and the high temperature side stage of the two-stage GM refrigerator 6, for example, a heat convection pipe using heat convection. 17A and 17B are a cross-sectional view and a top view showing the heat convection pipe 42. In the figure, reference numeral 61 denotes a flange of the heat convection pipe 42, which is made of a material having a high thermal conductivity, for example, copper, and one end face is grooved to increase the heat transfer area.
Reference numeral 62 is a pipe made of a material having a low thermal conductivity, for example, stainless steel. Further, in FIG. 16, reference numeral 44 is a valve for charging a cryogenic refrigerant, 45 is a helium cylinder for storing, for example, helium gas as a cryogenic refrigerant, 46 is a valve for vacuuming, and 47 is a vacuum pump. The valve 44 and the cylinder 45 constitute a filling means for filling the heat convection pipe 42 with the cryogenic refrigerant, and the valve 46 and the vacuum pump 47 constitute a pressure reducing means for reducing the pressure of the cryogenic refrigerant in the heat convection pipe 42. .

In this embodiment, the upper and lower flanges 61 of the heat convection pipe 42 are connected to the high temperature side stage 9 of the two-stage GM refrigerator 6.
And the low temperature side stage 8 are thermally connected. At the time of initial cooling, the valve 44 for filling helium is opened, and the capillary tube 4 is
The thermal convection pipe 42 is filled with helium gas via the No. 3. When the temperature of the high temperature side stage 9 of the two-stage GM refrigerator 6 is lower than the temperature of the low temperature side stage 8, the density of the helium gas existing near the high temperature side stage 9 is low.
It becomes larger than the density of helium gas existing in the vicinity of.
Therefore, convection occurs in the helium gas in the heat convection pipe 42. The heat transport by convection is larger than the heat transport by heat conduction, and the cold of the high temperature side stage 9 is transported to the low temperature side stage 8.

The convection in the heat convection pipe 42 continues while the temperature of the high temperature side stage 9 of the two-stage GM refrigerator 6 is lower than the temperature of the low temperature side stage 8, and when the temperature is reversed, the convection hardly occurs. When the temperature of the low temperature side stage 8 becomes lower than the temperature of the high temperature side stage 9, the vacuum evacuation valve 46 is opened and the helium gas in the heat convection pipe 42 is evacuated by the vacuum pump 47. When there is no helium gas in the heat convection pipe 42, convection no longer occurs. At this time, since the thermal conductivity of the heat convection pipe 62 is small, the high temperature side stage 9
To the low temperature side stage 8 can be ignored, and the temperatures reached by the low temperature side stage 8 and the superconducting coil 1 are almost the same as when the heat convection pipe 42 is not provided.

Usually, the superconducting coil 1 has a larger heat capacity than the radiation shield 4, and in the two-stage GM refrigerator 6, the high temperature side stage 9 has a higher refrigerating capacity than the low temperature side stage 8. In this embodiment, the flange 61 of the heat convection pipe 42 is thermally connected to the high temperature side stage 9 and the low temperature side stage 8 of the two-stage GM refrigerator so that the refrigerating capacity of the high temperature side stage 9 of the two-stage GM refrigerator 6 is high. Is used for the initial cooling of the superconducting coil 1, the initial cooling time of the superconducting coil 1 can be shortened. Although helium gas was used as the cryogenic refrigerant in this example, other cryogenic refrigerants such as nitrogen,
Applicable to argon, neon, hydrogen, air, oxygen, etc.

Example 16 18 is a sectional view showing a superconducting magnet according to Embodiment 16 of the present invention. In the figure, 48 is a heat transport pipe, for example, a heat convection pipe having a donut-shaped cross section. A more detailed structure of the heat convection pipe 48 is shown in FIG. 19 (a) and (b)
FIG. 4A is a cross-sectional view and a top view showing the heat convection pipe 48. In the figure, 63 is a flange of a heat convection pipe, which has a doughnut-shaped cross section, and is made of a material having a large thermal conductivity, for example, copper, and one end face is grooved to increase the heat transfer area. . Reference numeral 64 denotes a pipe made of a material having a small thermal conductivity, for example, stainless steel, and two pipes are arranged concentrically.

According to this embodiment, the heat convection pipe 48 is arranged so as to surround the cylinder between the high temperature side stage 9 and the low temperature side stage 8 of the two-stage GM refrigerator 6. Therefore, similarly to the fifteenth embodiment, the initial cooling time can be shortened by transferring heat between the high temperature side stage 9 and the low temperature side stage 8. Further, since the cylinder is surrounded, the high temperature side stage 9 of the two-stage GM refrigerator 6 and the heat convection pipe 4
8 and the heat transfer area of the low temperature side stage 8 and the heat convection pipe 48 can be made large. Therefore, since a temperature gradient is unlikely to be applied to the superconducting coil 1 during the initial cooling, it is possible to prevent the performance of the superconducting coil 1 from being degraded due to thermal stress. Further, in this embodiment, the heat convection pipe 48 can be expected to have an effect as a supporting member, and the number of supporting members can be reduced.

Example 17 20 is a sectional view showing a superconducting magnet according to Embodiment 17 of the present invention. In this embodiment, in addition to the structure of the fifteenth embodiment, the heat convection pipe 42
A plurality of, for example, two, are provided and are arranged at symmetrical positions with respect to the superconducting coil 1. As a result, the two-stage GM refrigerator 6
The heat transport from the high temperature side stage 9 to the low temperature side stage 8 is doubled, and the initial cooling time of the superconducting coil 1 by the low temperature side stage 8 can be further shortened. Further, by disposing the heat convection pipe 42 in a symmetrical position with respect to the superconducting coil 1, the temperature gradient of the superconducting coil 1 at the time of initial cooling can be relaxed, and the superconducting coil 1 due to thermal stress can be relaxed.
It is possible to prevent the performance degradation of. Although the number of the heat convection pipes 42 is two in this embodiment, the number is not limited to this, and two or more heat convection pipes can be similarly applied.

Further, in the fifteenth to seventeenth embodiments, as the heat transport pipe, the heat transport by the convection between the low temperature side stage 8 and the high temperature side stage 9 is described, but another method, for example, the one utilizing latent heat. Can also be realized by using.

Example 18. 21 is a sectional view showing a superconducting magnet according to Embodiment 18 of the present invention. In this embodiment, in addition to the structure of the ninth embodiment, the openings of the magnetic shield 30 are provided at symmetrical positions. As a result, in addition to the effect of the ninth embodiment, the electromagnetic force generated in the superconducting coil 1 becomes symmetrical due to the presence of the magnetic shield 30, the load on the support member 23 can be reduced, and a highly accurate magnetic field distribution can be obtained.

Although the two-stage GM refrigerator is used as the regenerator in the above embodiment, a single-stage GM refrigerator or a three-stage GM refrigerator is used.
It can also be applied to a multi-stage GM refrigerator. Also, the Gifford McMahon Cycle (GM) refrigerator is used as the cold storage refrigerator, but the Gifford McMahon cycle refrigerator here means a Gifford McMahon cycle It also includes a cold storage refrigerator that operates in an improved Solvay cycle similar to the McMahon refrigerator. Furthermore, the cold storage refrigerator is not limited to the Gifford-McMahon cycle refrigerator, and can be applied to, for example, a Stirling refrigerator, a pulse tube refrigerator, and a Billmeier refrigerator. Further, as the magnetic cold storage material of the cold storage type refrigerator, a material having a composition of Ho-Er-Ru was used, but another magnetic cold storage material, for example,
Er-Ni, Gd-Rh, Gd-Er-Rh, Er-Ni-Co, Ey-Yb-Ni
A magnetic regenerator material having a composition such as is also applicable.

[0092]

As described above, according to the invention of claim 1, the superconducting coil, the radiation shield surrounding the superconducting coil, the vacuum chamber surrounding the radiation shield, and the regenerator having a magnetic regenerator are provided. In the superconducting magnet, a magnetic shield that shields the magnetic field generated by the superconducting coil is provided, and the cold storage refrigerator is arranged on the opposite side of the magnetic shield from the superconducting coil, so that even if the superconducting coil generates a strong magnetic field. There is an effect that a superconducting magnet can be obtained that can prevent deterioration of the refrigerating capacity and can operate the cold storage type refrigerator stably in the long term without being affected by the magnetic field of the cold storage type refrigerator.

According to the invention of claim 2, claim 1
In addition to the invention, the regenerator has a low temperature side stage and a high temperature side stage, and cools the superconducting coil at the low temperature side stage and the radiation shield at the high temperature side stage. Even if the superconducting coil generates a strong magnetic field, the cold storage refrigerator is not affected by the magnetic field, and the refrigerating capacity can be prevented from deteriorating and stable over the long term. There is an effect that a superconducting magnet capable of operating the cold storage refrigerator is obtained.

According to the third aspect of the present invention, the superconducting coil unit, the second radiation shield, which comprises the superconducting coil, the first radiation shield surrounding the superconducting coil, and the first vacuum chamber surrounding the first radiation shield. , A superconducting coil having a low-temperature side stage, a regenerative refrigerator that cools a radiation shield with a high-temperature side stage, and a refrigerator unit composed of a second vacuum tank surrounding a second radiation shield, and a superconducting coil and a low-temperature stage with heat. Equipped with a conductive member for electrically connecting,
The superconducting coil unit and the refrigerator unit can be separated, the first and second radiation shields are thermally connected, and the first vacuum tank and the second vacuum tank are airtightly connected, so that maintenance can be facilitated and superconductivity can be improved. It is possible to reduce the influence of the magnetic field of the coil on the regenerator and to obtain a superconducting magnet that can stably operate the regenerator in the long term.

According to the invention of claim 4, claim 3
In addition to the above invention, a current lead for supplying a current to the superconducting coil is composed of a high temperature side, a low temperature side, and a connection part, and the high temperature side and the low temperature side current lead are arranged in a refrigerator unit, and the middle temperature part thereof is By thermally connecting to the radiation shield, the current lead can be placed away from the superconducting coil, and even if the superconducting coil generates a magnetic field, the current density of the current lead can be prevented from lowering and stable. There is an effect that a high-performance superconducting magnet can be obtained.

According to the invention of claim 5, claim 3
Alternatively, in addition to the invention of claim 4, the first vacuum tank and the second vacuum tank can be easily separated from each other by connecting the first vacuum tank and the second vacuum tank to each other in a flange structure and airtightly connecting to each other.
This has the effect of obtaining a superconducting magnet that can be easily maintained.

According to the invention of claim 6, claim 2
Further, in addition to the invention of any one of claims 5 to 5, by providing a heat exchanger for initially cooling the superconducting coil in the conductive member, there is an effect that a superconducting magnet capable of shortening the initial cooling time can be obtained.

Further, according to the invention of claim 7, a superconducting coil, a radiation shield surrounding the superconducting coil, a vacuum chamber surrounding the radiation shield, a cold storage for cooling the superconducting coil at a low temperature side stage, and a radiation shield for a high temperature side stage. -Type refrigerator and at least a part of which is made of a flexible body, and which is provided with a conductive member that thermally connects the superconducting coil and the low temperature side stage. The superconducting coil can be prevented from being subjected to thermal stress, and a superconducting magnet capable of stably operating the regenerator or the superconducting coil for a long term can be obtained.

According to the invention of claim 8, claim 7
In addition to the invention described above, the superconducting coil-side connection portion of the conductive member is formed of a plurality of flexible bodies, so that the superconducting coil can be prevented from having a large temperature gradient and the deterioration of the performance of the superconducting coil due to the temperature gradient can be prevented. There is an effect that a magnet is obtained.

According to the invention of claim 9, the superconducting coil, the superconducting coil are fixed, the vacuum chamber surrounding the superconducting coil, the magnetic shield surrounding the vacuum chamber, and the relative position between the magnetic shield and the vacuum chamber are set. A superconducting magnet that does not require a special structure to hold the vacuum and can easily adjust the magnetic field distribution by providing an adjusting mechanism that can adjust the relative position between the magnetic shield and the superconducting coil by adjusting. There is an effect that can be obtained.

According to the invention of claim 10, a superconducting coil, a radiation shield surrounding the superconducting coil, a superconducting coil fixed via the radiation shield, a vacuum chamber surrounding the radiation shield, and a magnetic chamber surrounding the vacuum chamber. A special structure is required to hold the vacuum because the shield and the adjustment mechanism that can adjust the relative position between the magnetic shield and the superconducting coil by adjusting the relative position between the magnetic shield and the vacuum chamber. In other words, there is an effect that a superconducting magnet whose magnetic field distribution can be easily adjusted can be obtained.

According to the invention of claim 11, a superconducting coil, a radiation shield surrounding the superconducting coil, a vacuum chamber surrounding the radiation shield, a cool storage for cooling the superconducting coil in the low temperature side stage, and the radiation shield in the high temperature side stage. -Type refrigerator, a heat transport pipe for transporting heat between the high temperature side stage and the low temperature side stage, a filling means for filling the heat transport pipe with a cryogenic refrigerant, and a decompression means for decompressing the cryogenic refrigerant of the heat transport pipe. As a result, there is an effect that a superconducting magnet can be obtained which can shorten the initial cooling time of the superconducting coil by utilizing the refrigerating capacity of the high temperature side stage of the regenerator.

According to the twelfth aspect of the invention, in addition to the eleventh aspect of the invention, a heat transport pipe having a toroidal cross section is surrounded by a cylinder between the high temperature side stage and the low temperature side stage of the regenerator. By performing heat transfer between the high temperature side stage and the low temperature side stage, the superconducting magnet can be cooled uniformly and the initial cooling time can be shortened.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a superconducting magnet according to Embodiment 2 of the present invention.

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

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

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

FIG. 6 is a sectional view showing a superconducting magnet according to Embodiment 6 of the present invention.

FIG. 7 is a sectional view showing a superconducting magnet according to Embodiment 7 of the present invention.

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

FIG. 9 is a sectional view showing a superconducting magnet according to Embodiment 9 of the present invention.

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

FIG. 11 is a sectional view showing a superconducting magnet according to Embodiment 11 of the present invention.

FIG. 12 is a sectional view showing a superconducting magnet according to Embodiment 12 of the present invention.

FIG. 13 is a top view (a) and a side view (b) around a conductive member and an initial cooling tube of a superconducting magnet according to a twelfth embodiment.

FIG. 14 is a sectional view showing the vicinity of a superconducting coil according to Embodiment 13 of the present invention.

FIG. 15 is a sectional view showing the vicinity of a superconducting coil according to Embodiment 14 of the present invention.

FIG. 16 is a sectional view showing a superconducting magnet according to Embodiment 15 of the present invention.

FIG. 17 is a sectional view (a) and a top view (b) showing a heat transport pipe according to Embodiment 15 of the present invention.

FIG. 18 is a sectional view showing a superconducting magnet according to Embodiment 16 of the present invention.

FIG. 19 is a sectional view (a) and a top view (b) showing a heat transport pipe according to Embodiment 16 of the present invention.

FIG. 20 is a sectional view showing a superconducting magnet according to Embodiment 17 of the present invention.

FIG. 21 is a sectional view showing a superconducting magnet according to Embodiment 18 of the present invention.

FIG. 22 is a sectional view showing an example of a conventional superconducting magnet.

FIG. 23 is a cross-sectional configuration diagram showing an example of a cold storage refrigerator.

FIG. 24 is a cross-sectional view showing the vicinity of a superconducting coil according to a conventional superconducting magnet.

FIG. 25 is a graph showing changes in temperature of a radiation shield and a superconducting coil due to cooling of a conventional regenerator.

[Explanation of symbols]

1 superconducting coil, 3a, 3b, 3c current lead, 4
Radiation shield, 5 vacuum tanks, 6, 27, 28 cold storage refrigerator, 8 low temperature side stage, 9 high temperature side stage, 30
Magnetic shield, 35 Conductive member, 36, 37 Flexible body, 38 Flange, 40 Heat exchanger, 41 Adjusting mechanism, 42, 48 Heat transport pipe, 45 Filling means, 47
Decompression means.

Claims (12)

[Claims] 1. A magnetic field generated by the superconducting coil in a superconducting magnet comprising a superconducting coil, a radiation shield surrounding the superconducting coil, a vacuum chamber surrounding the radiation shield, and a regenerator having a magnetic cold storage material. A superconducting magnet, comprising a magnetic shield for shielding, wherein the regenerative refrigerator is arranged on the opposite side of the magnetic shield from the superconducting coil. 2. A regenerator has a low temperature side stage and a high temperature side stage, and cools the superconducting coil by the low temperature side stage and the radiation shield by the high temperature side stage. The conductive member for thermally connecting the side stages is provided.
The superconducting magnet described. 3. A superconducting coil unit comprising a superconducting coil, a first radiation shield surrounding the superconducting coil, and a first vacuum chamber surrounding the first radiation shield, a second radiation shield, and the superconducting coil on a low temperature side stage. , A regenerator that cools the radiation shield at the high-temperature side stage, a refrigerator unit that includes a second vacuum chamber that surrounds the second radiation shield, and conduction that thermally connects the superconducting coil and the low-temperature side stage A member, the superconducting coil unit and the refrigerator unit can be separated, the first and second radiation shields are thermally connected, and the first vacuum tank and the second vacuum tank are airtightly connected. A superconducting magnet. 4. A current lead for supplying a current to a superconducting coil is composed of a high temperature side, a low temperature side, and a connecting portion, and the high temperature side and low temperature side current leads are arranged in a refrigerator unit, and the middle temperature portion is The superconducting magnet according to claim 3, wherein the superconducting magnet is thermally connected to two radiation shields. 5. The superconducting magnet according to claim 3 or 4, wherein the connecting portions of the first vacuum chamber and the second vacuum chamber have a flange structure and are hermetically connected to each other. 6. The superconducting magnet according to claim 2, wherein a heat exchanger for initially cooling the superconducting coil is provided on the conductive member. 7. A superconducting coil, a radiation shield enclosing the superconducting coil, a vacuum chamber enclosing the radiation shield, a regenerator for cooling the superconducting coil on a low temperature side stage, and the radiation shield on a high temperature side stage, and A superconducting magnet, at least a part of which is made of a flexible body, and which is provided with a conductive member which thermally connects the superconducting coil and the low temperature side stage. 8. The superconducting magnet according to claim 7, wherein the superconducting coil side connecting portion of the conductive member is constituted by a plurality of flexible bodies. 9. A superconducting coil, a vacuum chamber to which the superconducting coil is fixed and which surrounds the superconducting coil, a magnetic shield which surrounds the vacuum chamber, and a relative position between the magnetic shield and the vacuum chamber. A superconducting magnet, comprising an adjusting mechanism capable of adjusting a relative position between the magnetic shield and the superconducting coil. 10. A superconducting coil, a radiation shield surrounding the superconducting coil, a vacuum chamber in which the superconducting coil is fixed via the radiation shield and surrounds the radiation shield, a magnetic shield surrounding the vacuum chamber, and A superconducting magnet, comprising an adjusting mechanism capable of adjusting a relative position between the magnetic shield and the superconducting coil by adjusting a relative position between the magnetic shield and the vacuum chamber. 11. A superconducting coil, a radiation shield enclosing the superconducting coil, a vacuum chamber enclosing the radiation shield, a regenerator for cooling the superconducting coil on a low temperature side stage, and the radiation shield on a high temperature side stage, A heat transport pipe for transporting heat between the high temperature side stage and the low temperature side stage; a filling means for filling the heat transport pipe with a cryogenic refrigerant; and a decompression means for depressurizing the cryogenic refrigerant of the heat transport pipe. Is a superconducting magnet. 12. A doughnut-shaped heat transport pipe having a cross-sectional shape is disposed so as to surround a cylinder between a high temperature side stage and a low temperature side stage of a regenerator, and between the high temperature side stage and the low temperature side stage. The superconducting magnet according to claim 11, wherein heat transfer is performed by.