JP3646426B2 - Magnetization method of superconductor and superconducting magnet device - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a superconductor magnetization method and a superconducting magnet device in the case of using a bulk-shaped (bulky) superconductor as a magnet by capturing a high magnetic field.
[0002]
[Prior art]
For example, a RE-Ba-Cu-O-based (RE is Y or rare earth element) high-temperature superconductor manufactured by a melting method can capture a large magnetic field exceeding 1 T (Tesla), surpassing conventional permanent magnets. It is known to be a performance magnet.
As a method for easily magnetizing the superconductor, for example, Japanese Patent Application Laid-Open No. 6-168823 (Document 1), Japanase Journal of Applied Physics Vol 35 (1996) p. p. As described in 2114-2125 (Reference 2) and Japanese Patent Application No. 8-180058 (Reference 3), a method of applying a pulse magnetic field to a superconductor (pulse magnetization method) is disclosed.
[0003]
That is, according to the above documents 1 and 2, the high temperature superconductor is cooled to 77 K with liquid nitrogen, and then a pulse current is applied to the magnetizing coil arranged around the high temperature superconductor, whereby the superconductor is shown in FIG. A pulse magnetic field P is applied. As a result, the superconductor becomes a powerful magnet by capturing the magnetic field with a so-called pinning force.
According to this pulse magnetizing method, it is possible to magnetize a superconductor very easily compared with other conventional methods (FC method, ZFC method), and a superconducting magnet device using this method can be made compact. be able to.
[0004]
Further, in Document 2, it is reported that there is an optimum value (optimum applied magnetic field) for the magnitude of the pulse magnetic field to be applied in order to cause the superconductor to capture the maximum magnetic field. In addition, it has been reported that the optimum applied magnetic field in the pulse magnetization method is larger than the optimum applied magnetic field in the method of applying a static magnetic field after cooling without applying a magnetic field (ZFC method).
Reference 3 describes a method of cooling a superconductor using a refrigerator instead of liquid nitrogen.
[0005]
[Problems to be solved]
However, when trying to obtain a stronger magnet than the conventional pulse magnetizing method, there are the following problems. To clarify this problem, the mechanism by which the superconductor captures the magnetic field will be briefly explained again.
First, the superconductor can capture the magnetic flux by the pinning force determined by the critical current density J _{C at} a temperature equal to or lower than the superconducting transition temperature T _C. The density of magnetic flux that can be captured by this pinning force (capable magnetic field) is distributed with a constant gradient Q from the end in the width direction of the superconductor as shown in FIG. There is a characteristic that the part becomes the highest.
[0006]
The critical current density J _C that determines the pinning force is one of the characteristics inherent to the material of the superconductor, and generally increases as the temperature decreases. Therefore, if the temperature of the superconductor is lowered, the pinning force determined by the critical current density J _C is also improved, the gradient of the above-mentioned trappable magnetic field distribution becomes steep (Q → R), and the trappable magnetic field in the central portion is further increased. Becomes higher.
[0007]
Next, the magnetic field that the superconductor can actually capture cannot exceed the density of the magnetic flux that has penetrated into the superconductor (intrusion magnetic field). Therefore, in order to increase the magnetic field actually captured by the superconductor (captured magnetic field), it is necessary to inject as high a magnetic field as possible into the central portion of the superconductor.
On the other hand, the distribution of the penetrating magnetic field S entering the superconductor by the pulse magnetization method is as shown in FIG. The distribution of the shape is opposite to that of the superconductor, and the end of the superconductor is the highest and the center is the lowest.
[0008]
For this reason, as shown in FIG. 10A, when a sufficient distribution of the penetrating magnetic field S exceeding the distribution of the trappable magnetic field R can be provided, the maximum trapping magnetic field B is obtained. On the other hand, as shown in FIG. 10B, when the distribution of the penetration magnetic field S applied to the superconductor does not exceed the trappable magnetic field R in the central portion of the superconductor, the trapped magnetic field B in the central portion is particularly low. End up.
[0009]
In order to make a superconductor having the above characteristics a stronger magnet than before, it is necessary to increase the magnetic field that can be captured by the superconductor and to apply a high pulse magnetic field that can provide the corresponding intrusion magnetic field. is necessary.
In order to increase the trappable magnetic field of the superconductor, methods such as increasing the diameter of the superconductor, improving the critical current density J _C by controlling the structure of the superconductor itself, and improving the critical current density J _C by lowering the temperature of the superconductor, etc. There is.
[0010]
On the other hand, in order to apply a higher magnetic field than in the past in the pulse magnetization method, the number of turns of the magnetizing coil is increased, the power supply for supplying the pulse current is increased, and further, it can withstand a large electromagnetic force In addition, it is necessary to make the entire magnetized coil sturdy. This deteriorates the great feature that the superconductor can be easily magnetized by a simpler device than the other ZFC methods.
[0011]
The present invention has been made in view of such conventional problems, and a superconductor having excellent trappable magnetic field characteristics can capture a high magnetic field with a compact device, and a superconductor magnetizing method and a superconducting magnet. The device is to be provided.
[0012]
[Means for solving problems]
In the invention of claim 1, the temperature T ₀ of the central portion of the superconductor is set to be equal to or lower than the superconducting transition temperature T _C, and the temperature of the peripheral portion is set to a temperature T ₃ higher than the temperature T _{0 of the} central portion.
Applying a pulsed magnetic field to the superconductor,
Next, the superconductor magnetizing method is characterized in that the pulsed magnetic field is applied again by bringing the temperature of the entire superconductor close to T ₀ .
[0013]
What is most noticeable in the present invention is that when the first pulse magnetic field is applied to the superconductor, the temperature T ₀ of the central portion of the superconductor is set to be equal to or lower than the superconducting transition temperature T _C and the temperature of the peripheral portion is set. Is a temperature T ₃ higher than the temperature T _{0 of the} central portion.
[0014]
Next, the operation of the present invention will be described.
In the present invention, first, the temperature T ₃ at the peripheral portion is set higher than the temperature T _{0 at} the central portion of the superconductor. In this case, the outer diameter of the superconductor is reduced as a result of the properties such as the critical current density Jc described above.
[0015]
That is, in the peripheral portion where the temperature is higher than that of the central portion, the critical current density Jc is lower than that of the central portion, and the pinning force is also reduced. When the pinning force is reduced, the applied magnetic field can be easily penetrated (FIGS. 2A and 5A).
Therefore, when a pulse magnetic field is applied to a superconductor having a temperature distribution as described above, the entire superconductor has a uniform temperature distribution with the temperature T ₀ (FIGS. 2B and 5B), A strong applied magnetic field penetrates into the central part. For this reason, a stronger magnetic field than in the prior art is captured in the central portion of the superconductor (FIGS. 2A and 5A).
[0016]
However, at this time, the trapped magnetic field is small in the peripheral portion where the pinning force is small even if a strong magnetic field penetrates (FIGS. 2A and 5A).
Next, the temperature of the superconductor capturing a strong magnetic field in the central portion is brought close to the temperature T ₀ of the central portion as a whole. As a result, the critical current density J _C around the superconductor is improved, and its pinning force is equal to that of the central portion. Therefore, when a pulse magnetic field is applied to the superconductor again in this state, a stronger magnetic field is captured in the peripheral portion while maintaining the initial captured magnetic field.
[0017]
Therefore, in the present invention, even when the optimum applied magnetic field cannot be applied to a superconductor excellent in trappable magnetic field characteristics, the superconductor can capture a high magnetic field.
[0018]
Further, as in the invention of claim 2, the temperature T ₃ is preferably in a relationship of T ₃ > T _C. In this case, the peripheral portion at the temperature T ₃ can be brought into a normal conducting state. Therefore, the applied magnetic field penetrates to the peripheral part to the maximum, and the magnetic field penetrating the central part can be further increased (FIG. 2 (a)).
[0019]
Further, as in the third aspect of the invention, the temperature T ₃ may have a relationship of T _C ≧ T ₃ > T ₀ . That is, T ₃ is preferably equal to or higher than T _{C as} described above. However, when the temperature difference between T _C and T ₀ is large, it may be difficult to increase the temperature T _{3 of the} peripheral portion to T _C or higher. is there. However, even in this case, if at least T ₃ > T ₀ , the pinning force in the peripheral portion can be reduced, and the trapped magnetic flux density can be increased due to the increase in the magnetic field entering the central portion.
[0020]
Next, there is the following apparatus as a superconducting magnet apparatus using the superconductor magnetization method.
That is, as in the invention of claim 4, a superconductor disposed in a heat insulating container, a cooling device for cooling the superconductor, a magnetizing coil for applying a pulse magnetic field to the superconductor, There is a superconducting magnet device comprising a heater for heating the superconductor.
[0021]
What should be noted most in the superconducting magnet apparatus of the present invention is that it has the heater for heating the superconductor.
As this heater, a heater such as a manganin wire can be used.
[0022]
Further, the heat insulating container is for preventing heat from entering from the outside as much as possible, preventing the temperature of the superconductor from rising, and facilitating cooling of the superconductor. Specifically, for example, there are those with full-scale heat insulation measures such as a vacuum heat insulation tank equipped with a radiation shield plate. Further, for example, there is a simple one using a material with extremely low thermal conductivity such as FRP or polystyrene foam as a constituent material.
[0023]
The magnetizing coil generates a pulse magnetic field by energizing a single or a plurality of short-time currents (pulse currents) having various waveforms such as a sawtooth wave, a rectangular wave, a sine wave, and a capacitor discharge waveform. For example, when using capacitor discharge, the size of the pulse magnetic field and the rise time of the pulse can be controlled by adjusting the dimensions of the magnetized coil, the number of turns of the coil, the resistance, inductance, capacitance, etc. of the entire circuit. it can.
[0024]
In addition, the magnet coil is made of a normal conductor with an appropriate resistivity when the heat generated during pulse energization is used in the same way as the heating by a heater. Aluminum or superconductor is used.
Further, the arrangement of the magnetizing coils may be accommodated together with the superconductor in the heat insulating container as shown in the above-mentioned documents 1 and 2, or as shown in the document 3, You may arrange | position outside a container. Further, the magnetizing coil does not necessarily have to be around the superconductor, and may be opposed to at least a part of the upper surface or the lower surface of the superconductor.
[0025]
The cooling device directly cools the superconductor and can have various configurations as will be described later.
Further, the superconductor has a bulk shape (bulk shape), and the shape thereof can take various shapes such as a columnar shape and a prismatic shape. The superconductor has a so-called pinning point, and for example, a high-temperature superconductor described later is used.
[0026]
Next, the operation of the superconducting magnet device of the present invention will be described.
When magnetizing a superconductor in the apparatus of the present invention, first, the entire superconductor is brought to the temperature T ₀ of the central portion by the cooling device.
Next, the periphery of the superconductor is heated by the heater. As a result, in general, a superconductor with poor thermal conductivity has its peripheral portion only heated to the temperature T ₃ , and the central portion can maintain T ₀ for a while.
[0027]
In this state, a pulse magnetic field is applied to the superconductor by the magnetizing coil. As a result, as described above, a strong magnetic field is captured in the central portion of the superconductor.
Next, heating by the heater is stopped, and the entire superconductor is brought close to the temperature T ₀ by the cooling device. Then, a pulse magnetic field is applied to the superconductor again by the magnetizing coil. As a result, the trapped magnetic field around the superconductor increases as described above.
[0028]
As described above, according to the superconducting magnet apparatus of the present invention, the above-described superconductor magnetization method can be reliably and easily performed.
Moreover, since the superconducting magnet device of the present invention has a simple configuration as described above, it can be made very compact. Therefore, the superconducting magnet device of the present invention can be effectively used as a magnet device in various devices.
[0029]
According to a fifth aspect of the present invention, the cooling device is a refrigerator, and the refrigerator can be provided with a cold head for cooling the superconductor. In this case, the superconductor can be cooled efficiently and accurately, and the effect of the above-described superconductor magnetization method can be sufficiently exhibited.
[0030]
According to a sixth aspect of the present invention, the cooling device is a refrigerant circulation type cooling device, and the cooling device includes a refrigerant container containing the superconductor and the refrigerant, and a refrigerant transfer pipe in the refrigerant container. It is also possible to configure such that the refrigerant cooled by the refrigerant cooling device is circulated between the refrigerant container and the refrigerant container.
[0031]
In this case, highly accurate temperature control can be performed using the property of the refrigerant.
Moreover, as said refrigerant | coolant, liquid or gas, such as oxygen, nitrogen, neon, hydrogen, helium, is used, for example.
[0032]
According to a seventh aspect of the present invention, the cooling device is a refrigerant storage type cooling device, and the cooling device includes a refrigerant container containing the superconductor and the refrigerant, and the refrigerant in the refrigerant container. A configuration having an exhaust device for adjusting the vapor pressure can also be adopted.
In this case, the device configuration can be simplified.
[0033]
Further, as in the invention of claim 8, it is preferable that the superconductor is an RE-Ba-Cu-O system (where RE is Y, a rare earth element, or a combination of these elements). RE-Ba-Cu-O-based superconductors have numerous so-called pinning points and are in a superconducting state at a relatively high temperature. For this reason, it is possible to exhibit extremely excellent performance as a superconducting magnet used in a relatively high temperature range.
[0034]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
A superconducting magnet apparatus using a superconductor magnetizing method according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the superconducting magnet device 1 of this example includes a superconductor 10 disposed in a heat insulating container 2, a refrigerator 3 as a cooling device for cooling the superconductor 10, and a superconductor 10. It comprises a magnetizing coil 4 for applying a pulsed magnetic field and a heater 5 for heating the superconductor 10.
[0035]
The superconductor 10 has a disk shape with a radius a, and the material thereof is RE-Ba-Cu-O (where RE is Y, rare earth element, or a combination of these elements). As shown in FIG. 1, the heater 5 is disposed so as to surround the outer periphery of the superconductor 10. Manganin wire was used for the heater 5.
[0036]
As shown in FIG. 1, the heat insulating container 2 uses FRP and stores a superconductor 10 and a cold head 31 of the refrigerator 3 described later. The inside of the heat insulating container 2 is in a vacuum state in order to prevent heat from entering from the outside as much as possible.
As shown in FIG. 1, the magnetizing coil 4 is disposed outside the heat insulating container 2 so as to be positioned around the superconductor 10. Further, the magnetizing coil 4 is electrically connected to a pulse power source 41 using capacitor discharge.
[0037]
The cooling device in this example includes a refrigerator 3 having a compressor 32 and a cold head 31, as shown in FIG. The cold head 31 is a portion that takes heat and cools it, and is connected to the superconductor 10 via a copper member 35 having excellent thermal conductivity.
[0038]
Next, a procedure for magnetizing the superconductor 10 using the superconducting magnet device 1 of this example will be described.
In magnetizing the superconductor 10, first, the refrigerator 3 is operated to cool the superconductor 10 to a temperature T ₀ that is not higher than the superconducting transition temperature T _C as a whole. Next, the heater 5 is operated to heat the peripheral portion of the superconductor 10 to a temperature T ₃ higher than the superconducting transition temperature T _C.
[0039]
The distribution of the temperature T inside the superconductor 10 immediately after heating is shown in the upper part of FIG. In the figure, the horizontal axis represents the radial position of the superconductor 10 and the vertical axis represents temperature. As can be seen from the figure, since the superconductor 10 of this example has low thermal conductivity, even if the temperature of the peripheral portion becomes T ₃ , the temperature of the central portion remains at T ₀ for a while. .
[0040]
Next, in this state, a pulse magnetic field having a strength of 6 (FIG. 8) is applied to the superconductor 10. The distribution of the intrusion magnetic field S ₁ entering the superconductor 10 is shown in the lower part of FIG. In the figure, the horizontal axis represents the radial position of the superconductor 10 and the vertical axis represents the magnetic flux density. As can be seen from the figure, the intrusion magnetic field S ₁ distribution that has entered the superconductor 10 has the applied intensity 6 as it is in the peripheral portion E where the temperature is equal to or higher than the superconducting transition temperature T _C.
Then, the invasion magnetic field gradually decreases from the portion where the temperature is lower than the superconducting transition temperature T _C. This intrusion magnetic field S ₁ distribution is larger than the intrusion magnetic field S ₂ (the lower diagram in FIG. 2B) that intrudes when a pulse magnetic field having the same strength is applied when the temperature is T _{0 as} a whole.
[0041]
The distribution of the trappable magnetic field R ₁ of the superconductor 10 in this temperature state is shown in the lower diagram of FIG. As can be seen from the figure, the trappable magnetic field R ₁ is distributed as if the outer diameter is small because the peripheral portion E has no pinning force. Since the trappable magnetic field R ₁ distribution is included in the intrusion magnetic field S ₁ distribution, the trapped magnetic field B ₁ is the strength of the trappable magnetic field R ₁ itself.
[0042]
Next, the heating of the superconductor 10 by the heater 5 is stopped, and the superconductor 10 is cooled to the temperature T ₀ by the refrigerator 3 again as shown in the upper diagram of FIG.
In this state, a pulse magnetic field is again applied to the superconductor 10 by the magnetizing coil 4. The distribution of the intrusion magnetic field S ₂ that has entered the superconductor 10 is shown in the lower diagram of FIG. As can be seen from the figure, the intrusion magnetic field S ₂ distribution that has entered the superconductor 10 has a parabolic shape that decreases from the end of the superconductor 10 toward the center. This penetration magnetic field S ₂ distribution is generally smaller than the previous penetration magnetic field S ₁ distribution (when the first pulse magnetic field is applied) (FIG. 2A).
[0043]
Further, the trappable magnetic field R ₂ distribution of the superconductor 10 in this temperature state is shown in the lower diagram of FIG. As can be seen from the drawing, the current captureable magnetic field R ₂ is larger than the previous capture magnetic field R ₁ . Then, the central portion of the trapped magnetic field R ₂ distribution exceeds the penetration magnetic field S ₂ distribution. Therefore, the magnetic field B ₂ captured by the current penetration magnetic field S ₂ increases only in the peripheral portion of the superconductor 10, and the central portion maintains the previous state.
Therefore, the finally captured magnetic field distribution B has a shape as shown in FIG.
[0044]
On the other hand, FIG. 4 shows the distribution of the trapped magnetic field B when the pulse magnetic field is applied once in the conventional method, that is, when the temperature of the superconductor 10 is totally T ₀ . As can be seen from the comparison between FIG. 4 and FIG. 3A, the superconductor 10 magnetized in this example has a significantly increased trapped magnetic field density at its central portion, and can become a more powerful magnet. Understand.
Note that the trapping magnetic field B obtained in this example is slightly leveled over time as shown in FIG.
[0045]
Embodiment 2
In the present embodiment, as shown in FIGS. 5 (a) shown above, the heating temperature T ₃ of the peripheral portion of the superconductor during the first-time pulse magnetic field applied in the embodiment 1 described above in T _C below the temperature did. In addition, the superconducting magnet device, the magnetization procedure, and the like were the same as in the first embodiment.
[0046]
FIG. 5A shows a penetrating magnetic field S ₁ , a trappable magnetic field R ₁ , and a trapping magnetic field B ₁ corresponding to the temperature distribution T in the superconductor 10 when the first pulse magnetic field is applied in this example. As can be seen from the figure, the penetration magnetic field S ₁ in this example is smaller than that in the first embodiment because the peripheral portion is slightly smaller than that in the first embodiment, and therefore the entire portion is smaller. However, even in this case, a large magnetic field still invades as compared with the case where the temperature of the superconductor 10 is entirely T ₀ (FIG. 5B).
[0047]
Therefore, as shown in FIG. 5 (a), by application of the first pulse magnetic field, a strong trapped magnetic field B ₁ is obtained in particular the central portion. Next, by the second application of the pulse magnetic field, the captured magnetic field B ₂ in the peripheral portion is increased as in the first embodiment.
Therefore, also in this example, the superconductor 10 can capture a magnetic field larger than the conventional one as a whole. In addition, the same effects as those of the first embodiment can be obtained.
[0048]
Embodiment 3
As shown in FIG. 6, the superconducting magnet device 104 of this example uses a refrigerant circulation type cooling device 7 as a cooling device for the superconductor 10. The refrigerant circulation type cooling device 7 includes a refrigerant container 71 containing a superconductor 10 and a magnetizing coil 4 surrounded by a heater 5 and a refrigerant 9, and refrigerant cooling connected to the refrigerant container 71 via a refrigerant transfer pipe 72. Device 73.
[0049]
The refrigerant 9 cooled by the refrigerant cooling device 73 is circulated between the refrigerant container 71 and the inside of the refrigerant container 71. The refrigerant container 71 is housed in the vacuum container 76 through a vacuum layer 75 whose pressure is reduced to a vacuum state. The vacuum container 76, the vacuum layer 75, and the refrigerant container 71 constitute a heat insulating container 204.
[0050]
Further, liquid nitrogen is used as the refrigerant 9 in this example. Therefore, the temperature of the superconductor 10 can be accurately controlled to 77 K or less, which is the boiling point of liquid nitrogen. In other respects, the same effects as those of the first embodiment can be obtained.
[0051]
Embodiment 4
As shown in FIG. 7, the superconducting magnet device 105 of this example uses a refrigerant storage type cooling device 8 as a cooling device for the superconductor 10. This refrigerant storage type cooling device 8 adjusts the vapor pressure of the refrigerant 9 in the refrigerant container 81, the refrigerant container 81 containing the superconductor 10 and the magnetizing coil 4 surrounded by the heater 5, and the refrigerant 9. Vacuum evacuation device 83.
[0052]
The refrigerant container 81 and the vacuum exhaust device 83 are connected to each other by an exhaust 82, and a pressure gauge 821 is disposed in the exhaust pipe 82.
Further, the refrigerant container 81 is accommodated in the vacuum container 86 through the vacuum layer 85 decompressed to a vacuum state. These vacuum container 86, vacuum layer 85, and refrigerant container 81 constitute a heat insulating container 205.
[0053]
In the case of this example, the vapor in the refrigerant container is exhausted by the vacuum evacuation device 83, whereby the evaporation of the refrigerant 9 is promoted, and the temperature of the refrigerant 9 can be lowered by the heat of evaporation. Therefore, the temperature control of the refrigerant 9, that is, the temperature control of the superconductor 10 can be easily performed.
In other respects, the same effects as those of the first embodiment can be obtained.
[0054]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a superconductor magnetization method and a superconducting magnet device that can cause a superconductor excellent in trappable magnetic field characteristics to capture a high magnetic field with a compact device. .
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of a superconducting magnet device according to a first embodiment.
FIGS. 2A and 2B show the superconductor temperature, intrusion magnetic field, trappable magnetic field, and trapped magnetic field when (a) the first pulse magnetic field is applied and (b) the second pulse magnetic field is applied. Explanatory drawing which shows distribution.
FIGS. 3A and 3B are explanatory views showing (a) a finally captured magnetic field distribution and (b) a captured magnetic field distribution that has changed over time in Embodiment 1. FIG.
4 is an explanatory diagram showing a captured magnetic field density of a comparative example in Embodiment 1. FIG.
FIG. 5 shows the superconductor temperature, intrusion magnetic field, trappable magnetic field, and trapped magnetic field when (a) the first pulse magnetic field is applied and (b) the second pulse magnetic field is applied. Explanatory drawing which shows distribution.
6 is an explanatory diagram showing a configuration of a superconducting magnet device according to Embodiment 3. FIG.
7 is an explanatory diagram showing a configuration of a superconducting magnet device according to Embodiment 4. FIG.
FIG. 8 is an explanatory diagram showing a pulse magnetic field in a conventional example.
FIG. 9 is an explanatory diagram showing (a) a trappable magnetic field distribution and (b) an intrusion magnetic field distribution in a conventional example.
FIGS. 10A and 10B are explanatory diagrams showing a captured magnetic field when (a) an optimum applied magnetic field is applied and (b) a magnetic field less than the optimum applied magnetic field is applied in a conventional example.
[Explanation of symbols]
1,104,105. . . Superconducting magnet device,
10. . . Superconductor,
2,204,205. . . Insulated container,
3. . . refrigerator,
31. . . Cold head,
4). . . Magnetized coil,
5. . . heater,
7). . . Refrigerant circulation type cooling device,
8). . . Refrigerant storage type cooling device,
9. . . Refrigerant,

Claims (8)

The temperature T ₀ of the central portion of the superconductor is set to be equal to or lower than the superconducting transition temperature T _C, and the temperature of the peripheral portion is set to a temperature T ₃ higher than the temperature T _{0 of the} central portion.
Applying a pulsed magnetic field to the superconductor,
Next, the method of magnetizing the superconductor, wherein the temperature of the entire superconductor is brought close to T ₀ and a pulse magnetic field is applied again. According to claim 1, said temperature T ₃ is, T _3> magnetizing method features and to superconductor relation that T _C. According to claim 1, said temperature T ₃ is magnetizing method of the superconductor, characterized in that a relation of _{T C ≧ T 3> T 0} . A superconductor disposed in a heat insulating container, a cooling device for cooling the superconductor, a magnetizing coil for applying a pulsed magnetic field to the superconductor, and a heater for heating the superconductor; A superconducting magnet device comprising: 5. The superconducting magnet device according to claim 4, wherein the cooling device is a refrigerator, and the refrigerator is provided with a cold head for cooling the superconductor. 5. The cooling device according to claim 4, wherein the cooling device is a refrigerant circulation type cooling device, and the cooling device includes a refrigerant container storing the superconductor and the refrigerant, and a refrigerant connected to the refrigerant container via a refrigerant transfer pipe. A superconducting magnet device comprising a cooling device and configured to circulate a refrigerant cooled by the refrigerant cooling device between the inside of the refrigerant container. 5. The cooling device according to claim 4, wherein the cooling device is a refrigerant storage type cooling device, and the cooling device adjusts the vapor pressure of the refrigerant in the refrigerant container, the refrigerant container storing the superconductor and the refrigerant. And a superconducting magnet device. The superconductor according to any one of claims 4 to 7, wherein the superconductor is a RE-Ba-Cu-O system (where RE is Y, a rare earth element, or a combination of these elements). Superconducting magnet device.

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