JP2000102112A - Superconducting magnet for magnetically levitated train - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of a superconducting magnet against quench prevention by reducing eddy current heat generation due to magnetic field change caused by vehicle oscillation during traveling. SOLUTION: The thickness of a low electrical resistance material layer 20 is partly changed, where the layer covers a surface or is plated on the surface of a superconducting coil accommodating vessel 2 which cools a superconducting coil 1 and fixes it to a specified position. In particular, the thickness of low electric resistance material layers 21, 22 of levitating direction upper side region where an eddy current is liable to be generated by magnetic field change of low frequency is increased, and the electric resistance value is reduced. A radiant heat shield and a vacuum thermal insulation vessel which surround the accommodating vessel 2 may be constituted of low electric resistance material in which the plate thickness in a region where an eddy current is liable to be generated in increased. The thickness of the low electric resistance material layer may not be increased but material having low resistivity may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic levitation train system including a levitation coil and a propulsion coil installed on a ground track side and a superconducting magnet mounted on a vehicle.

[0002]

2. Description of the Related Art A magnetic levitation train has a superconducting magnet using a superconducting coil mounted on a vehicle, and obtains a levitation force and a propulsion force by applying an attractive force and a repulsive force to a normal conducting coil arranged on the ground. Things. Referring to FIG. 7, the arrangement of the vehicle-mounted coil and the ground coil of the side-surface levitation type magnetic levitation train will be described. FIG. 7A is a schematic sectional view of a vehicle and a guideway for guiding the vehicle by sandwiching the vehicle from both sides, and FIG. 7B is a schematic diagram of a coil fixed to the guideway. Vehicle 1
0, a plurality of superconducting coils 11a, 11
b are fixed side by side. The guideway 13 has floating coils 14a, 15a,
14b, 15b and the propulsion coils 16a, 16b are fixedly arranged so as to face the superconducting coils 11a, 11b, respectively. Floating coils 14a, 15a, 14
b and 15b are short-circuit coils and are not connected to the power supply. On the other hand, a current is applied to the propulsion coils 16a and 16b such that the polarity periodically changes from the substation. .

FIG. 8 shows a conventional superconducting magnet for a magnetically levitated train. FIG. 8A is a partially cutaway front view of the superconducting magnet, and FIG.
(B) is an AA 'cross-sectional view thereof. Superconducting coil 1
Are disposed in a superconducting coil storage container (hereinafter, simply referred to as a storage container) 2, the storage container 2 is disposed in a radiant heat shield 3, and the radiant heat shield 3 is further disposed in a vacuum heat insulating container 4. A support member 5 is fixed to the storage container 2, and a copper plating layer 6 is formed on a surface of the storage container 2. Since the storage container 2 needs to hold and fix the superconducting coil 1, it is made of stainless steel having high rigidity and strength.
The superconducting coil 1 is cooled by providing a liquid helium flow path therein.

[0004] One of the problems in putting a magnetic levitation train into practical use is how to prevent quench (superconductivity destruction) of the superconducting magnet. The cause of the quench is considered to be a heat load, a magnetic field fluctuation, and the like. In particular, the heat load is related to the capability of the liquid helium refrigerator and is the most urgent problem to be solved. Thermal loads include heat from the outside due to conduction, radiation, etc., eddy current heat generated due to fluctuations in the magnetic field of the ground coil, and frictional heat generated by the electromagnetic force generated by the action of the eddy current and magnetic field. Various measures have been taken in the past. For example, with respect to heat intrusion from the outside, the heat intrusion due to radiant heat or convection is prevented by providing the radiant heat shield 3 and the vacuum heat insulating container 4. With respect to the eddy current heat generation, measures such as forming a high-purity copper plating layer 6 on the surface of the superconducting coil storage container 2 and coating aluminum having a low electric resistivity are taken.

[0005] It has been considered that the plating or coating of the container with this low electric resistance material is particularly effective as a measure for reducing eddy current heat generation due to fluctuations in the ground coil magnetic field during high-speed running. In the magnetic levitation system, a pulsating magnetic field associated with passing through the levitation coils 14a, 15a, 14b, and 15b is constantly applied to the superconducting magnet when the train is running. According to the current design, the frequency of this magnetic field fluctuation is 309 Hz when traveling at 500 km / h. At this frequency, the magnitude of the eddy current generated in each part of the superconducting magnet due to the magnetic field fluctuation is determined by the inductance without depending on the electric resistance, so the value of the eddy current does not change even if the electric resistance value of the material forming the magnet parts is changed . Therefore, the lower the electric resistance value, the smaller the eddy current heat generation. Based on this knowledge, a measure taken to suppress eddy current heat generation in the liquid helium cooling system is to plate or coat the container 2 with high-purity copper or aluminum having a low electric resistivity. .

As a measure for reducing the eddy current heat generation, in addition to the method of coating the storage container 2 with the low electric resistance material 6 as described above, in order to reduce the eddy current secondaryly caused by the vibration due to the electromagnetic force, A method of suppressing vibration by devising a supporting structure has been adopted.

[0007]

As described above, the cause of the eddy current heat generation that has been considered up to now has been the magnetic field fluctuation occurring at the running frequency. However, the magnetic field fluctuation applied to the superconducting magnet does not always occur only at the running frequency. For example, vehicle sway caused by air resistance, imbalance of left and right thrusts, or installation error of a levitation coil is caused by 1
Very low frequency magnetic field fluctuations that occur in the low frequency range of 10 Hz to 10 Hz due to vehicle sway also apply to the superconducting magnet. However, conventionally, no measures have been considered to reduce such eddy current heat generation in a low frequency range, and there has been a problem that heat generation is excessive in a conventional magnet. To avoid this, it is conceivable to reduce the electric resistance of the low-resistance material sufficiently. However, there is a problem that the reverse current generated at the time of excitation becomes large, so that the superconducting coil cannot be excited.

The present invention reduces the eddy current heat generated by the superconducting magnet caused by the eddy current heat generated by the magnetic field fluctuation generated at the running frequency and the magnetic field fluctuation in the low frequency range due to the vehicle shake.
It is an object of the present invention to provide a highly reliable superconducting magnet that does not easily cause quench.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a superconducting coil having a superconducting wire wound thereon, a superconducting coil container for cooling the superconducting coil and fixing the coil at a predetermined position, and a low electric power coated or plated on the surface of the container. This can be achieved by partially changing the thickness of the low electric resistance material layer in the superconducting magnet for a magnetic levitation train including the resistance material layer.
In addition, the present invention can be achieved by partially configuring one or both of the radiant heat shield and the vacuum insulated container surrounding the storage container with low electric resistance materials having different thicknesses. In particular, by making the thickness of the constituent material on the upper side in the floating direction of the superconducting magnet larger than the thickness of the constituent material on the lower side in the floating direction, the heat generation reducing effect can be enhanced.

It is another object of the present invention to provide a superconducting magnet for a magnetic levitation train including a superconducting coil wound with a superconducting wire and a housing for cooling the superconducting coil and fixing the superconducting coil in a predetermined position. This can be achieved by installing low electric resistance materials having different electric resistivity. In addition, the present invention can be achieved by partially configuring one or both of the radiant heat shield and the vacuum heat insulating container surrounding the storage container with low electric resistance materials having different electric resistivity. In particular, a high effect can be obtained by setting the electrical resistivity of the constituent material on the upper side in the floating direction of the superconducting magnet lower than the electrical resistivity of the constituent material on the lower side in the floating direction.

In the background of the problem of eddy current heat generated in the storage container in the low frequency range, sufficient eddy current is not easily generated in the vacuum heat insulating container or the radiant heat shield due to the low frequency, so that the external magnetic field may be dislodged. There is a phenomenon of adding to the storage container. On the other hand, in the low electric resistance layer on the surface of the superconducting coil storage container, since the resistance is reduced, the eddy current flows at the maximum value limited by the inductance. Therefore, the heat generation of the low electric resistance layer caused by the magnetic field fluctuation due to the vibration of the vehicle in the low frequency range where the shielding effect by the vacuum heat insulating container and the radiation heat shield is not effective cannot be ignored.

FIG. 2 illustrates the relationship between the eddy current heat generated in the storage container due to the external magnetic field fluctuation and the electric resistance of the storage container, using the frequency of the external magnetic field fluctuation as a parameter. Curve 18 shows the relationship when the frequency of the external magnetic field fluctuation is 309 Hz, and curve 19 shows the relationship when the frequency is 2 Hz. As shown in the figure, for a magnetic field fluctuation at a certain frequency, the eddy current heating is maximized at a specific electric resistance value, and decreases with a larger or smaller electric resistance value. Draw. Further, as the frequency of the external magnetic field fluctuation increases, the chevron curve moves toward the high resistance side as a whole as shown by the arrow in the figure.

As a method of reducing the eddy current heat generation,
(1) reducing external magnetic field fluctuation due to vehicle shaking;
(2) The resistance value of the low electric resistance layer is increased, and the electric resistance is limited to the electric resistance in the frequency range of the vehicle sway, so that the eddy current does not flow, and the optimal electric resistance value that reduces the heat generation to some extent even in the traveling frequency range is searched. it, i.e. the resistance of the low resistance layer of R ₂ or FIG. 2, or (3) lowering the resistance value of the conventional or a low electric resistance layer, i.e., FIG. 2 the resistance value of the low resistance layer it is conceivable to the R ₁ or less.

The cause of the magnetic field fluctuation due to vehicle shaking is a change in the levitation coil current on the ground track side. Since the levitation coil exerts an electromagnetic force to dampen the vehicle sway, the facing figure-eight coil is connected by a conducting wire called a null flux line, and current flows back and forth between the levitation coils. An eddy current is generated on the side of the superconducting magnet due to the magnetic field fluctuation caused by this current change. Therefore, with respect to the above (1), magnetic field fluctuations have to be allowed as long as damping of fluctuation is required. Regarding (2), it is necessary to anticipate a certain allowable calorific value, and there is a great possibility that the capacity of the refrigerator is increased. Further, it is extremely difficult to select an electrical resistivity that suppresses heat generation at a low frequency or a high frequency so as to fall within the allowable range of the current capacity of the liquid helium refrigerator.
Regarding (3), when the electric resistance is lowered, a new problem arises in that heat generation due to the reverse current at the time of demagnetization increases. In addition, when the thickness of the low electric resistance layer is increased in order to reduce the electric resistance, there are severe structural restrictions such as weight and size.

As a method of reducing the heat load of the liquid helium system, in addition to a method of reducing the eddy current heat itself of the superconducting coil storage container, a vacuum heat insulating container and a radiant heat shield are used to increase the shielding effect of the external magnetic field and store the heat. There is also a method of reducing the magnetic field fluctuation received by the low electric resistance layer of the container. In order to enhance the magnetic field shielding effect, the electric resistance of each component should be reduced so that the current can easily flow even at a low frequency. However, the only way to lower the electrical resistance is to lower the electrical resistivity of the material or increase the thickness. In most cases, the electrical resistivity is determined by the rigidity and strength required of the constituent materials, and there is little room for selection. Regarding the plate thickness, increasing the thickness is directly related to increasing the weight, and is therefore a choice that should be avoided as much as possible. These problems are also encountered when it is desired to further reduce the electric resistance of the low electric resistance layer in order to reduce the heat generation of the low electric resistance layer.

However, as long as the eddy current distribution is known, there is no need to change the electric resistivity or the plate thickness of the entire constituent material, and only the electric resistance of the portion where the eddy current flows can be reduced. FIG. 3 simulates the eddy current distribution on the vacuum insulated container due to the vehicle sway from this point of view, and the eddy current density becomes higher as the eddy current streamlines drawn as closed curves in the figure become more crowded.

FIG. 3 shows that the high current density portion exists in the upper half of the vacuum insulated container facing the ground coil. This is because there are two types of electromotive force of the levitation coil current, which are caused by the levitation force and the guide force. The current due to the levitation force tends to flow in the opposite direction above and below the levitation coil, whereas the current due to the guide force tends to flow in the same direction above and below. Therefore, the current of the levitation coil increases on the upper side where the directions of the two electromotive forces coincide, and decreases on the lower side where the two electromotive forces are in opposite directions. The upper and lower differential currents flow across the null flux line into the facing coil. The difference between the upper and lower floating coil currents is the difference in the amount of magnetic field fluctuation exerted on the facing vacuum insulated container, which causes the eddy current distribution to be different between the upper and lower parts.

Such knowledge of the distribution of the eddy current is obtained only by performing a three-dimensional eddy current analysis on the vehicle sway. In order to reduce the eddy current heat generation, the electric resistance of a portion having a high current density corresponding to the eddy current flow path in FIG. 3 may be reduced. Similarly, by reducing the electrical resistivity or increasing the thickness of the portion corresponding to the eddy current flow path on the radiant heat shield or the storage container, the electrical resistance of the eddy current flow path decreases, and thus the current becomes easier to flow, As a result, the magnetic field intrusion into the low electric resistance layer or the storage container is suppressed,
Since the eddy current generated in the low electric resistance layer is reduced, the heat generation is reduced, and a superconducting magnet that does not easily cause quench can be obtained.

Regarding the low electric resistance layer, for example, when the electric resistance of the upper half is reduced to 1/2 and the thickness is doubled, the heat generation can be reduced to about 1/4 of the conventional one. In this case, the weight of the low electric resistance layer is increased by 1.
The heat generation due to the reverse current at the time of excitation and demagnetization is considered to be about twice that of the conventional case, and is sufficiently acceptable. In particular, heat generated by the reverse current may be reduced by adjusting the excitation / demagnetization speed. By these measures for reducing heat generation, a highly reliable superconducting magnet with lower heat generation and less quenching than before can be obtained.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments. 1A and 1B are diagrams showing an embodiment of the present invention, in which FIG. 1A is a front view, and FIG. 1B is a sectional view taken along the line AA ′. Superconducting coil 1 is held in storage container 2. The storage container 2 is made of stainless steel having high rigidity and strength because it is necessary to hold and fix the superconducting coil 1.
Has cooled. A copper plating 20 having a thickness of about 0.3 mm is applied to the entire surface of the storage container 2, and the plating is thickened at a part of the antinode of the coil. The thickened portion 21 is located at the upper portion on the side facing the ground coil, and is the portion where the largest amount of eddy current flows due to vehicle shaking (see FIG. 3). By thickening the plating of about 1.0 mm, and the electric resistance of the portion below R ₁ shown in FIG. 2, for example reduce the 1 × 10 ^-6 Ω. A portion 2 where eddy currents are particularly likely to flow among the thickened portions 21
In No. 2, a thicker plating is formed in a ring shape to sufficiently lower the electric resistance.

According to the present embodiment, since the electric resistance of the eddy current flow path is low, heat generation due to the eddy current is reduced, and a highly reliable superconducting magnet which is hardly quenched can be obtained.
FIG. 4 is a diagram showing another embodiment of the present invention, in which (a)
Is a front view, and (b) is an AA ′ cross-sectional view thereof. The superconducting coil storage container 2 is made of stainless steel having high rigidity and strength because it is necessary to hold and fix the superconducting coil 1. The superconducting coil 1 is provided with a liquid helium flow path therein.
Has cooled. Aluminum having a low electrical resistivity (electrical resistivity of about 2 × 10 ⁻⁷ Ωm) 2 is provided on the entire surface of the storage container 2.
3 is coated, but the upper side facing the ground coil side where eddy currents are likely to flow due to low frequency magnetic field fluctuations caused by vehicle shaking has higher purity than aluminum material coated on other parts. To make the electrical resistivity 1 × 10 ^-7 Ωm
A slightly reduced aluminum material 24 is coated. Therefore, the heat generation in this portion is reduced by the lower electric resistivity, and it is difficult to quench, and a highly reliable superconducting magnet can be obtained.

FIG. 5 shows another embodiment of the present invention.
(A) is a front view, (b) is the AA 'sectional drawing.
The radiant heat shield 25 surrounds the storage container 2 to which the support member 5 is attached, and the storage container 2 having a surface plated with copper 6 stores the superconducting coil 1 therein. The radiant heat shield 25 of the present embodiment is made of aluminum having a high thermal conductivity of about 3 mm in thickness to be used after cooling to the temperature of liquid nitrogen, and a portion having a plate thickness of about 5 mm is partially formed. 26. This thick part 26
Is a portion that faces the ground coil and is located at an upper portion in the flying direction, and is a portion where the eddy current due to vehicle shaking flows through the radiant heat shield in the largest amount.

In the present embodiment, the plate thickness is not completely increased along the eddy current distribution as in the embodiment shown in FIG. Thick parts are provided. By changing the plate thickness along the eddy current distribution as shown in FIG. 1, it is possible to achieve an optimal design in which heat generation is suppressed as much as possible and at the same time the weight is reduced as much as possible. However, from the viewpoint of ease of manufacture, a simple shape as in this embodiment is easier to process and the processing cost is smaller.

As described above, the electric resistance is reduced by increasing the thickness of the portion corresponding to the flow path of the eddy current, and a large amount of electric current is supplied to shield the fluctuation of the magnetic field reaching the internal low electric resistance layer. The effect can be improved. Therefore, the eddy current generated in the copper plating layer 6 of the superconducting coil storage container 2 is reduced,
As a result, heat generation is reduced, so that a highly reliable superconducting magnet that is hardly quenched can be obtained.

FIG. 6 shows another embodiment of the present invention.
(A) is a front view, (b) is the AA 'sectional drawing.
The superconducting coil 1 has a support member 5 attached thereto and is disposed in a storage container 2 having a copper plating layer 6 formed on the surface. The storage container 2 is disposed in the radiant heat shield 3, and the radiant heat shield 3 is further disposed in the vacuum heat insulating container 27. The vacuum insulated container 27 is made of an aluminum material having an electric resistivity of about 6 × 10 ⁻⁸ Ωm, and a portion 28 thereof is made of pure aluminum having an electric resistivity of about 3 × 10 ⁻⁸ Ωm, which is lower than other parts. It is made of material. The portion 28 made of a material having a low electric resistivity is located at an upper portion on the side facing the ground coil, and is a portion where the eddy current density due to the vehicle sway is high. Therefore, according to the present embodiment, by reducing the electric resistance of the eddy current flow path and allowing a large amount of current to flow, it is possible to enhance the effect of shielding magnetic field fluctuations reaching the internal low electric resistance layer.

Conventionally, a vacuum insulated container is made of a lightweight aluminum alloy having strength and rigidity. To reduce the electric resistance, it is difficult to form the whole from pure aluminum having a low electric resistance. However, if pure aluminum is partially used as in this embodiment, the strength can be secured and the heat generation reducing effect is large. Further, in the present embodiment, unlike the embodiment shown in FIG. 4, the low electric resistance material is not completely arranged along the eddy current distribution, but the portion covering the area where the eddy current is distributed, A rectangular low electric resistance material is arranged. The low electric resistance portion 28 and the other portion 27 of the vacuum insulated container are cut into their respective shapes and then joined by a method such as welding. However, both cutting and welding are straight lines rather than complicated curved shapes. Since the processing is easier, the manufacturing cost can be reduced.

In the above embodiment, the method of increasing the thickness of the constituent material and the method of using a material having a small electric resistivity have been described as a method of partially reducing the electric resistance value. If a material having a small electric resistivity is used with a large plate thickness in combination with the above method, a higher electric resistance value reduction effect can be obtained.

[0028]

According to the present invention, by partially changing the thickness and the electric resistivity of the constituent material, the electric resistance of the portion where the eddy current is generated can be selectively reduced, so that the strength and rigidity are impaired. In addition, it is possible to reduce the eddy current heat generation in the liquid helium-based low electric resistance material without increasing the weight extremely. Moreover, in the radiation heat shield and the vacuum heat insulation container, by reducing the electric resistance value of the portion where the eddy current flows, the shielding effect of the magnetic field penetration into the low electric resistance layer can be increased, and as a result, the low electric resistance layer Eddy current heat generation can be reduced. Therefore, since heat generation causing quench can be suppressed, a highly reliable superconducting magnet can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment in which heat generation is reduced by partially changing the thickness of a low electric resistance layer.

FIG. 2 is a diagram illustrating the relationship between resistance and heat generation.

FIG. 3 is an analysis diagram showing an eddy current distribution on a vacuum insulated container due to vehicle shaking.

FIG. 4 is an explanatory diagram of an embodiment in which the electric resistivity of the constituent material of the low electric resistance layer is partially changed.

FIG. 5 is an explanatory view of an embodiment in which the thickness of the radiation heat shield is partially changed.

FIG. 6 is an explanatory view of an embodiment in which the electrical resistivity of the constituent materials of the vacuum insulated container is partially changed.

FIG. 7 is an explanatory diagram of a vehicle-mounted superconducting coil and a ground coil of a magnetic levitation train.

FIG. 8 is an explanatory view of a conventional superconducting magnet.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Superconducting coil, 2 ... Superconducting coil storage container, 3 ... Radiant heat shield, 4 ... Vacuum heat insulation container, 5 ... Support member, 6 ...
Copper plating layer, 10: vehicle, 11a, 11b: on-board superconducting coil, 13: guide way, 14a, 15a: floating coil, 14b, 15b: floating coil, 16a, 16b ...
Propulsion coil, 20: copper plating layer, 21, 22: thick copper plating layer, 23, 24: aluminum coating, 25: radiant heat shield, 27: vacuum insulation container

Continued on the front page (72) Inventor Yoko Furukawa 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Eiji Fukumoto 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd.Hitachi Research Laboratories (72) Inventor Masayuki Shibata 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd.Hitachi Research Laboratories (72) Inventor Teruhiro Takizawa Tachizawa, Hitachi 1-1 1-1, Hitachi, Ltd.Hitachi Plant, Hitachi, Ltd. (72) Inventor Motoaki Terai 1-4-1, Meieki Station, Nakamura-ku, Nagoya-shi, Aichi Tokai Passenger Railway Co., Ltd. (72) Inventor Tetsu Inadama Aichi 1-4-1 Meieki Station, Nakamura-ku, Nagoya-shi, Japan Inside Tokai Passenger Railway Co., Ltd. (72) Takashi Mizutani 2-8-8 Hikaricho, Kokubunji-shi, Tokyo F-term F-Term (in reference) 4M114 AA15 AA22 AA40 BB01 CC03 CC16 DA02 DA12 DA52 5H113 AA07 BB03 CC04 CC08 CD02 CD13 CD16 CD18 DB03 DB09 DB14 DB19 JJ05 JJ10 KK02 KK10

Claims (8)

[Claims] 1. A superconducting coil wound with a superconducting wire, a superconducting coil housing for cooling the superconducting coil and fixing it in a predetermined position, and a low electric resistance material layer coated or plated on the surface of the superconducting coil housing. A superconducting magnet for a magnetic levitation train, wherein the thickness of the low electric resistance material layer is partially changed. 2. A vacuum insulation container, a radiant heat shield disposed in the vacuum insulation container, a superconducting coil storage container disposed in the radiant heat shield, and a superconducting coil disposed in the superconducting coil storage container. A superconducting magnet for a magnetically levitated train, wherein one or both of the radiant heat shield and the vacuum insulated container are partially made of low electric resistance materials having different thicknesses. 3. The superconducting magnet for a magnetically levitated train according to claim 1, wherein the thickness of the low electrical resistance material is asymmetrical in the vertical direction in the floating direction. 4. The superconductivity for a magnetically levitated train according to claim 1, wherein the thickness of at least a part of the low electric resistance material in the upper part in the levitation direction is thicker than the thickness of the low electric resistance material in the lower part in the levitation direction. magnet. 5. A superconducting magnet for a magnetic levitation train, comprising: a superconducting coil wound with a superconducting wire; and a superconducting coil storage container for cooling the superconducting coil and fixing the coil at a predetermined position.
A superconducting magnet for a magnetic levitation train, wherein a low electric resistance material having a different electric resistivity is partially provided on a surface of the superconducting coil storage container. 6. A vacuum insulated container, a radiant heat shield disposed in the vacuum insulated container, a superconducting coil container disposed in the radiant heat shield, and a superconducting coil disposed in the superconducting coil container. A superconducting magnet for a magnetically levitated train, wherein one or both of the radiation shield and the vacuum insulated container are partially made of a low electric resistance material having a different electric resistivity. 7. The superconducting magnet for a magnetically levitated train according to claim 5, wherein the electric resistivity of the low electric resistance material is asymmetrical in the vertical direction in the levitation direction. 8. The magnetic device according to claim 5, wherein the electric resistivity of the low electric resistance material in at least a part of the upper part in the flying direction is lower than the electric resistivity of the low electric resistance material in the lower part of the flying direction. Superconducting magnet for levitation train.