JPH10116725A - Superconducting magnet device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to remove heat generated due to an AC loss effectively even when an exiting operation and a degaussing operation are performed at high speed and to operate this device stably without generating a normal conducting transition. SOLUTION: In a device, a superconducting coil is formed in such a way that a superconducting wire 10 is wound on a cooling bobbin 5 to be layerlike, that its side faces are supported by a cooling flange 4A and a cooling flange 4B and that a cooling plate 6 is arranged on the outer circumference. The device is cooled to a cryogenic temperature so as to be used by using an attached refrigerating machine while the cooling flange 4A, the cooling bobbin 5, the cooling plate 6 and the cooling flange 4B are cooled by superconduction. In this case, a superconducting cooling plate 11 which is composed of a copper alloy as a good heat-conducting material is inserted between layers of the wound superconducting wire 10, and both ends of them are inserted into grooves formed on the cooling flanges 4A, 4B so as to be bonded thermally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting magnet device used for cooling by heat conduction using a refrigerator, such as for component analysis using a strong magnetic field or for energy storage.

[0002]

2. Description of the Related Art In recent years, as the refrigerating capacity of a refrigerator has been improved, a superconducting magnet device of a type in which a refrigerator is attached to a superconducting coil and the superconducting coil is cooled by heat conduction has been actively developed. FIG. 8 is a cross-sectional view schematically showing the basic configuration of a conventional refrigerator-cooled superconducting magnet apparatus, showing a cross section passing through the center axis of a superconducting magnet apparatus having a room-temperature high-magnetic-field space in the center. It is. In the figure,
1 is a superconducting coil formed by winding a superconducting wire in a solenoid shape, 2 is a radiation shield disposed around the superconducting coil 1 and blocking heat radiation from the outside to insulate heat, and 3 is a vacuum shield that surrounds these and evacuates the inside. This is a vacuum vessel that is held at a temperature and insulated. 7 is a refrigerator for cooling the superconducting coil 1;
Reference numeral 9 denotes a compressor that supplies compressed helium gas to the refrigerator 7 to control the operation, and 9 denotes a current lead that supplies current to the superconducting coil 1 from a power supply (not shown) to excite it.

[0003] As shown in the figure, a refrigerator 7 is connected to a cooling flange 4 for supporting the superconducting coil 1 from the side and a radiation shield 2. Cool to a low temperature of about 80K. As shown in the enlarged sectional view of FIG.
The superconducting wire 10 is wound around a cylindrical cooling bobbin 5 in a layered manner. The cooling flange 4 is provided on both sides and a cooling plate 6 is provided on the outer periphery. By cooling one end of the lower cooling flange 4 in the figure by the refrigerator 7, the cooling bobbin 5, the cooling plate 6 and the upper cooling flange 4 connected thereto are cooled by heat conduction and further surrounded by them. The superconducting coil 1 is cooled to a temperature lower than the critical temperature of the superconducting wire by heat conduction, and is maintained in a superconducting state. In the superconducting state, the superconducting coil 1 is
, A strong magnetic field is generated, and at the same time, magnetic energy proportional to the inductance is stored in the superconducting coil 1. When used as a static magnetic field,
Superconducting coil 1 between superconducting coil 1 and current lead 9
There is a case where a switch (permanent current switch) for short-circuiting is incorporated to be used as a so-called permanent current mode.

[0004]

As described above, in the superconducting magnet device of the refrigerator cooling type, the cooling flange 4 is provided.
Is cooled by a refrigerator 7, and the superconducting wire 10 is cooled by heat conduction through the cooling flange 4, the cooling bobbin 5, and the cooling plate 6.
Is cooled. In the superconducting state, if the current flowing in the superconducting wire 10 is constant, there is no loss generated in the superconducting coil 1. Therefore, if the heat that enters the superconducting coil 1 from the outside is removed by the refrigerator 7, the superconducting coil 1 becomes The superconducting state is maintained, and a steady operation can be performed.

However, when the current flowing through the superconducting wire 10 fluctuates, for example, when the superconducting coil 1 is excited or demagnetized, or when a current having an AC component is applied, an AC loss specific to the superconductor occurs. This AC loss depends on the fluctuation speed of the magnetic field, and if high-speed excitation or demagnetization is performed, the loss becomes large. On the other hand, in the conventional refrigerator-cooled superconducting magnet device, the cooling flange 4, the cooling bobbin 5, and the cooling plate 6 surrounding the superconducting coil 1 are all formed of a material having good thermal conductivity, resulting in an excessive temperature difference. However, since the superconducting coil 1 is a laminated body of the superconducting wires 10 as shown in FIG. 6, the superconducting coil 1 has a drawback that effective heat conduction performance is inferior. Therefore, when an AC loss occurs, not only a large load is applied to the refrigerator 7 to remove the AC loss, but also a temperature gradient is generated inside the superconducting coil 1, and the temperature particularly at the center increases. If the AC loss is large and the temperature rise is excessive, the temperature will be higher than the critical temperature, and the superconducting wire 10 may cause a normal conduction transition (quench) in which the superconducting wire 10 transitions from the superconducting state to the normal conducting state.

The present invention has been made in order to solve this problem. Even in the case of high-speed excitation and demagnetization, heat generation due to AC loss is effectively removed, and temperature rise is suppressed. To provide a superconducting magnet device that can operate stably without causing a normal conduction transition.

[0007]

According to the present invention, there is provided a superconducting coil comprising a superconducting wire wound in a layer on a bobbin and supported by a flange, and a superconducting coil insulated. In a superconducting magnet device equipped with a surrounding radiation shield, a vacuum vessel that insulates and surrounds the radiation shield, and a refrigerator that cools the superconducting coil by heat conduction through a cooling member and keeps it at a cryogenic temperature, a layer between superconducting wires is used. Then, a superconducting coil is formed by interposing a conductive cooling plate made of a good heat conductive metal material, for example, copper or a copper alloy, or aluminum or an aluminum alloy.

(2) The conduction cooling plate is provided with at least one slit in the circumferential direction. (3) The end of the conduction cooling plate is joined to the flange via soldering. (4) Alternatively, a superconducting coil in which a superconducting wire is wound in layers on a bobbin and supported by a flange, a radiation shield that insulates and surrounds the superconducting coil, a vacuum container that insulates and surrounds the radiation shield, and cools the superconducting coil In a superconducting magnet device equipped with a refrigerator that cools by heat conduction through members and keeps it at a very low temperature, a conductive cooling plate made of a good heat conductive ceramic material, for example, aluminum nitride is interposed between layers of the superconducting wires. Thus, a superconducting coil is formed.

(5) Further, in (1) to (4), the end of the conduction cooling plate is inserted into a groove provided in a flange for supporting the superconducting coil. The heat conductive soft metal material is interposed, and the end of the conductive cooling plate is joined to the flange. (6) Alternatively, a conductive cooling plate made of a good heat conductive ceramic material is used, and the outer periphery of both ends is plated with gold or silver, and this plated portion is joined to the flange by soldering, or the both ends are connected with good heat. A heat conductive member made of a conductive metal is joined, and the joined portion is joined to the flange by soldering.

(7) The flange is provided with at least one slit in the circumferential direction. In the case of the above (1) or (4), a conductive cooling plate having good thermal conductivity is disposed inside the superconducting coil, so that heat generated in the superconducting wire due to, for example, AC loss or the like is conducted. It will diffuse through the cooling plate. Therefore, the effective thermal conductivity inside the superconducting coil is improved, and the temperature gradient is reduced, so that the internal temperature rise is suppressed, and the risk of normal conduction transition is reduced.

According to the above (2), even when the conduction cooling plate is made of a highly conductive metal material,
Since the loss due to the induced circulating current generated in the conduction cooling plate due to the fluctuating magnetic field is avoided, the loss added by the interposed conduction cooling plate is suppressed very small, and the temperature rise due to the loss applied to the conduction cooling plate is also suppressed very small. . Further, in the case of (3), (5), or (6), since both ends of each conduction cooling plate are connected to the flange, heat generated by AC loss generated inside the superconducting coil is directly transmitted to the flange. In particular, if soldering or bonding with soft metal is used, the thermal contact between each conduction cooling plate and the flange will be good, and the contact thermal resistance will be kept low. The temperature will be kept lower.

According to the above (7), the loss due to the induced circulating current generated in the flange due to the fluctuating magnetic field is avoided, so that the temperature rise at both ends of the conduction cooling plate connected to the flange is suppressed. The temperature rise inside the superconducting coil is also suppressed.

[0013]

FIG. 1 is an enlarged sectional view showing a superconducting coil portion of an embodiment of a superconducting magnet device according to the present invention, which is shown in comparison with the conventional example of FIG. FIG.
In the superconducting coil of the present embodiment shown in FIG. 1, a superconducting wire 10 is wound in layers on a cooling bobbin 5 made of a good heat conductive metal material such as copper or copper alloy having a central axis (not shown) on the left side in the figure. Each is provided with a conductive cooling plate 11 made of a copper alloy of a good heat conductive metal material, and both ends of the conductive cooling plate 11 are made of a good heat conductive metal material such as copper or a copper alloy. The cooling flanges 4A and 4B are connected by being inserted into grooves provided in the flat cooling flanges 4A and 4B. A cooling plate 6 also made of a good heat conductive metal material such as copper or a copper alloy is arranged on the outer periphery of the superconducting coil. The cryogenic end of a refrigerator (not shown) is connected to the end of the cooling flange 4A, as in the conventional example shown in FIG. 8, and the superconducting wire 10 forming the superconducting coil is connected to the cooling flange 4A and the cooling bobbin. 5, the cooling plate 6, the cooling flange 4B, and the heat conduction through the conduction cooling plate 11 are cooled and kept at an extremely low temperature. Particularly, in the present configuration, since the conduction cooling plate 11 is provided, heat generated in the internal superconducting wire 10 is transferred to the cooling flanges 4A and 4B through the conduction cooling plate 11 and cooled. Therefore, even when AC loss is involved, heat generation is effectively removed, and the rise in internal temperature can be suppressed to a low level.

In the configuration shown in FIG. 1, superconducting wire 1
Although the conduction cooling plate 11 is interposed for each of the 0 layers, a superconducting coil with small internal heat generation such as AC loss may be inserted for each of a plurality of layers. FIG.
FIG. 2 is a cross-sectional view corresponding to the AA plane of the superconducting coil unit in FIG. 1. As shown in the figure, the conductive cooling plate 11 made of a copper alloy and interposed in each layer is configured to be divided into a plurality in the circumferential direction. Therefore, even if the conduction cooling plate 11 is made of a copper alloy having excellent conductivity, there is no possibility that a circulating induction current is generated due to the fluctuating magnetic field, and the eddy current loss is suppressed to a very small level. In addition, when the number is divided into a larger number, the eddy current loss is more minutely suppressed. Further, in this configuration, the cooling bobbin 5 made of a good heat conductive metal material such as copper or copper alloy is used.
The cooling plate 6 is also provided with a slit 13, and the cooling plate 6 also made of a good heat conductive metal material such as copper or a copper alloy is provided with the slit 12, thereby preventing the generation of a circulating induction current due to a fluctuating magnetic field.

FIG. 3 is a cross-sectional view corresponding to the BB plane of the superconducting coil portion of FIG. As shown in the figure, the end of the conduction cooling plate 11 divided into four is inserted into a groove 15 formed in a cooling flange 4B made of a good heat conductive metal material such as copper or a copper alloy. Further, the cooling flange 4B is provided with a slit 14 to prevent the generation of a circulating induction current due to the fluctuating magnetic field, thereby avoiding heat generation. Therefore, the temperature rise at both ends of the conduction cooling plate 11 connected to the cooling flange 4B is suppressed, and the temperature rise inside the superconducting coil is also suppressed.

FIG. 4 is an enlarged view of a portion C of the superconducting coil shown in FIG. As shown in the figure, the end of the conduction cooling plate 11 is inserted into a groove 15 formed by machining on the cooling flange 4B, and is joined by solder 16. Therefore, the conduction cooling plate 11 and the cooling flange 4B are joined while minimizing the thermal resistance, and the heat generated inside the superconducting coil is effectively transmitted and removed. Also, a good thermal connection can be obtained by inserting a good heat conductive soft metal such as indium between the groove 15 and the conduction cooling plate 11 and joining it instead of joining with the solder 16.

In the above embodiment, the conduction cooling plate 11
Is made of a good heat conductive metal, but may be made of a good heat conductive ceramic material such as aluminum nitride. Since the good thermal conductive ceramic material has a high specific resistance and negligible eddy current loss, it is not necessary to divide the conduction cooling plate into a plurality as shown in FIG. 2 or FIG. Good.

When a good heat conductive ceramic material is used, a good heat conductive soft metal such as indium is inserted between the groove 15 and the conductive cooling plate 11 in a configuration similar to FIG. Good thermal connection can be obtained by using the joining method. Further, as shown in the sectional view of the main part in FIG. 5, a plating layer 17 of gold plating or silver plating is formed on the outer periphery of both ends of the conduction cooling plate 11A made of a good heat conductive ceramic material, and this part is formed by the cooling flange 4B. A method of inserting into the groove 15 and joining with the solder 16 or, as shown in FIG. 6, a heat transfer plate made of a good heat conductive metal material on the outer periphery of both ends of a conductive cooling plate 11B made of a good heat conductive ceramic material. The member 18 is fitted and thermally and mechanically firmly connected, and the fitted heat transfer member 18 is connected to the solder 16
7, or a conductive cooling plate 11C made of a good heat conductive ceramic material, as shown in FIG. 7, and made of a good heat conductive metal material by brazing at both ends. Even if the method of connecting the heat transfer member 18A and joining the heat transfer member 18A to the groove 15 of the cooling flange 4B by the solder 16 is used, a good thermal connection between the conductive cooling plate and the flange is obtained, and the heat is effectively generated. , And the temperature rise is suppressed and stable operation is performed.

[0019]

As described above, according to the present invention, (1) a superconducting coil in which a superconducting wire is wound in layers on a bobbin and supported by a flange, a radiation shield and a radiation shield for insulating and surrounding the superconducting coil A superconducting magnet device equipped with a vacuum vessel that insulates and surrounds a superconducting coil and a refrigerator that cools the superconducting coil by heat conduction through a cooling member and maintains the superconducting coil at a cryogenic temperature. Since a superconducting coil is formed by interposing a conductive cooling plate made of a material, for example, copper or a copper alloy, or aluminum or an aluminum alloy, even in a device that performs high-speed excitation and demagnetization, AC loss is reduced. The accompanying heat generation is effectively removed, the temperature rise is suppressed, and a superconducting magnet device that can operate stably without causing normal conduction transition is obtained. Was.

(2) It is more preferable that the conduction cooling plate is provided with at least one slit in the circumferential direction, because eddy current loss generated in the conduction cooling plate can be suppressed to a negligible level. is there. (3) If the end of the conduction cooling plate is soldered and joined to a flange supporting the superconducting coil, heat conduction between the conduction cooling plate and the flange is improved, so that heat generation is more effectively removed, It is suitable.

(4) Even if a superconducting coil is formed by interposing a conductive cooling plate made of a good heat conductive ceramic material, for example, aluminum nitride, between the layers of the superconducting wire, it is possible to reduce the AC loss generated inside. Since the accompanying heat generation is effectively removed and the rise in temperature is suppressed, a superconducting magnet device that can operate stably without causing normal conduction transition can be obtained.

(5) In the above, the end of the conduction cooling plate is inserted into a groove formed in the flange, and further joined to the flange through a good heat conductive soft metal material such as indium. By doing so, the thermal connection between the conduction cooling plate and the flange is improved, so that heat is more effectively removed, which is preferable. (6) A conductive cooling plate made of a good thermal conductive ceramic material is used, and gold plating or silver plating is applied to the outer periphery of both ends thereof. Even if a heat conducting member made of a conductive metal is joined and this joined part is joined to the flange by soldering, the heat connection between the conduction cooling plate and the flange is improved, so that heat is more effectively removed. It is preferred.

(7) If the flange is made of a metal material having at least one slit in the circumferential direction, heat generated in the flange can be suppressed,
Since the temperature at the end of the conduction cooling plate is kept low, the heat generated inside the superconducting coil is effectively removed, and a superconducting magnet device that can be operated stably without causing a normal conduction transition is obtained. .

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of a superconducting coil portion of a superconducting magnet device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view corresponding to the AA plane of the superconducting coil unit of FIG. 1;

FIG. 3 is a cross-sectional view corresponding to plane BB of the superconducting coil unit of FIG. 1;

FIG. 4 is an enlarged view of a part C of the superconducting coil part of FIG. 1;

FIG. 5 is an enlarged sectional view of a main part of a superconducting coil unit according to a second embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a main part of a superconducting coil according to a third embodiment of the present invention.

FIG. 7 is an enlarged sectional view of a main part of a superconducting coil according to a third embodiment of the present invention.

FIG. 8 is a cross-sectional view schematically showing a basic configuration of a conventional superconducting magnet device of a refrigerator cooling type.

9 is an enlarged sectional view of a superconducting coil portion of the superconducting magnet device of FIG.

[Explanation of symbols]

 Reference Signs List 1 superconducting coil 2 radiation shield 3 vacuum vessel 4 cooling flange 4A cooling flange 4B cooling flange 5 cooling bobbin 6 cooling plate 7 refrigerator 10 superconducting wire 11 conductive cooling plate 11A conductive cooling plate 11B conductive cooling plate 11C conductive cooling plate 12 slit 13 slit 14 slit 15 groove 16 solder 17 plating layer 18 heat transfer member 18A heat transfer member

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kiyoshi Takida 1-1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-ku, Kanagawa Prefecture Inside Fuji Electric Co., Ltd.

Claims (12)

[Claims] 1. A superconducting coil comprising a superconducting wire wound on a bobbin in a layered manner and supported by a flange, a radiation shield for insulating and surrounding the superconducting coil, a vacuum vessel for insulating and surrounding the radiation shield, and cooling the superconducting coil. In a superconducting magnet device provided with a refrigerator that cools by heat conduction through a member and maintains the temperature at a cryogenic temperature, the superconducting coil includes a conductive cooling plate made of a good heat conductive metal material between layers of the superconducting wire. A superconducting magnet device characterized by being formed as follows. 2. The superconducting magnet device according to claim 1, wherein the high thermal conductive metal material is copper, a copper alloy, aluminum, or an aluminum alloy. 3. The superconducting magnet device according to claim 1, wherein the conduction cooling plate has at least one slit in a circumferential direction. 4. The superconducting magnet device according to claim 1, wherein an end of the conduction cooling plate is joined to a flange supporting the superconducting coil by soldering. 5. A superconducting coil in which a superconducting wire is wound around a bobbin in layers and supported by a flange, a radiation shield for insulating and surrounding the superconducting coil, a vacuum vessel for insulating and surrounding the radiation shield, and cooling the superconducting coil. In a superconducting magnet device provided with a refrigerator that cools by heat conduction through members and keeps the temperature at a cryogenic temperature, the superconducting coil has a conductive cooling plate made of a good heat conductive ceramic material interposed between layers of the superconducting wire. A superconducting magnet device characterized by being formed as follows. 6. A superconducting magnet apparatus according to claim 5, wherein said ceramic material having good thermal conductivity is aluminum nitride. 7. The superconducting magnet device according to claim 1, wherein an end of said conduction cooling plate is inserted into a groove provided in a flange for supporting a superconducting coil. 8. An end portion of the conductive cooling plate made of a good heat conductive ceramic material is joined to a flange supporting a superconducting coil via a good heat conductive soft metal material. Item 8. A superconducting magnet device according to item 7. 9. The superconducting magnet device according to claim 8, wherein said soft metal material having good thermal conductivity is indium. 10. A conductive cooling plate made of a good thermal conductive ceramic material, the outer periphery of which is plated with gold or silver, and the plated portion is joined to a flange supporting a superconducting coil by soldering. The superconducting magnet device according to claim 5, wherein 11. A conductive cooling plate made of a good heat conductive ceramic material having a heat conductive member made of a good heat conductive metal coupled to both ends thereof, the heat conductive member being a flange for supporting a superconducting coil. The superconducting magnet device according to claim 5, wherein the superconducting magnet device is joined by soldering. 12. The method according to claim 12, wherein said flange is at least one circumferentially.
The superconducting magnet device according to any one of claims 1 to 11, wherein the superconducting magnet device is made of a metal material provided with slits.