JPH07211546A - Apparatus and method for magnetizing and demagnetizing high-temperature superconductive bulk magnet - Google Patents

Abstract

PURPOSE:To conduct magnetization and demagnetization easily and rapidly by providing the device with a hollow bulk magnet, a magnetic field generating coil which is located so as to face the hollow bulk magnet, and a device which makes a part or the whole body of the hollow bulk magnet normal conductive. CONSTITUTION:A magnetizing and demagnetizing device for a high-temperature superconductive bulk magmet consists of a hollow bulk magnet 11, a magnetic field generating coil 21, and a motor 31, At the time when the magnetic field generating coil generates a specified magnetic field, the heater 31 is turned on and the hollow bulk magnet 11 is turned into a normal conductive state. Then, a magnetic flux generated by the magnetic field generating coil 21 is allowed to interlink with the hollow bulk magnet 11. With the magnetic flux interlinking with the hollow bulk magnet 11, the heter 31 is turned off and thereby the hollow bulk magnet 11 is turned into a superconductive state. At that time, the specific magnetic flux remains interlinking with the bulk magnet 11. When the hollow bulk magnet 11 comes to a superconductive state, the magnetic field generating coil 21 is gradually demagnetized and electric current is caused to flow in the hollow bulk magnet 11 which is in a superconductive state in such a direction that the interlinking magnetic flux may be kept constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high temperature superconducting bulk magnet excitation / demagnetization apparatus and method.

[0002]

2. Description of the Related Art Conventionally, as shown in Japanese Patent Application No. 2-232904, in order to pass a permanent current through a closed loop, a magnetic field is printed while the temperature of the closed loop conductor is raised and the temperature of the closed loop conductor is lowered. There is known a method of removing a magnetic field after making a closed loop into a superconducting state.

[0003]

In the prior art, since liquid nitrogen was used to change the temperature of the entire system for switching between superconducting and normal conducting states, it takes time to excite and demagnetize a high temperature superconducting bulk magnet. There was a point.

An object of the present invention is to quickly and easily demagnetize a high temperature superconducting bulk magnet.

[0005]

The above object includes a hollow bulk magnet, a magnetic field generating coil installed so as to face the hollow bulk magnet, and a device for normalizing part or all of the hollow bulk magnet. This is achieved by using a high temperature superconducting bulk magnet excitation / demagnetization device.

[0006]

In the excitation / demagnetization device for a high temperature superconducting bulk magnet of the present invention, the high temperature superconducting bulk magnet is excited in the following procedure. When the magnetic field generating coil is excited so that a predetermined magnetic field is generated and the high temperature superconducting bulk magnet is made to have normal conductivity, magnetic fluxes are linked to the hollow bulk magnet. After that, when the hollow bulk magnet is made superconducting and the magnetic field generating coil is gradually demagnetized,
A current is induced in the hollow bulk magnet in a direction that hinders the change of the magnetic flux, and when the current in the magnetic field generating coil becomes zero, a predetermined permanent current remains in the hollow bulk magnet.

Degaussing is performed in the following procedure. When a permanent current is flowing through the hollow bulk magnet, the current of the bulk magnet can be made zero by exciting the magnetic field generating coil until a predetermined magnetic field is generated. After that, when the bulk magnet is made to have normal conductivity and the magnetic field generating coil is demagnetized, no current flows through the bulk magnet and the demagnetization is completed.

The high-temperature superconducting bulk magnet excitation / demagnetization device of the present invention comprises a hollow bulk magnet, a means for normalizing part or all of the hollow bulk magnet, and a magnetic field generating coil. It becomes easy to apply a magnetic field to the magnet, make the bulk magnet normal and superconducting, and remove the magnetic field applied to the bulk magnet. That is, a series of operations for demagnetizing the hollow bulk magnet becomes easy.

In the high temperature superconducting bulk magnet exciter / demagnetizer of the present invention, since a heater, an external magnetic field, or a high temperature refrigerant is used as means for making the bulk magnet normally conductive, the bulk magnet can be easily made normally conductive in a short time. . Further, if the heater, the application of the external magnetic field, and the spraying of the high-temperature refrigerant are performed in a pulse shape, the time required for the normal conduction is further shortened, and the heat generation due to the normal conduction is reduced.

Since the superconducting coil is used as the magnetic field generating coil in the high temperature superconducting bulk magnet excitation / demagnetization device of the present invention, the high temperature superconducting bulk magnet can be excited up to a high magnetic field. Moreover, since the normal conductor is used as the external magnetic field generating coil, a pulsed magnetic field can be easily generated.

Since the even number of external magnetic field generating coils are arranged at the target positions, the influence on the magnetic field generating coils can be eliminated.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiments.

FIG. 1 shows a first embodiment of the present invention. 1 shows an outline of an excitation / demagnetization device for a high temperature superconducting bulk magnet, which is composed of a hollow bulk magnet 11, a magnetic field generating coil 21, and a heater 31. As for the order of excitation, first, the magnetic field generating coil 21 is excited until a predetermined magnetic field is generated. At this time, the hollow bulk magnet 11 may be in a superconducting state, or the heater 31 may be previously struck to be in a normal conducting state. When the magnetic field generating coil 21 generates a predetermined magnetic field, the heater 31 is struck to bring the hollow bulk magnet 11 into a normal conducting state. Then, as shown in FIG. 2, the hollow bulk magnet 11
The magnetic flux 41 generated by the magnetic field generation coil 21 is linked to the.
The heater 31 is turned off in a state where the magnetic fluxes are interlinked, and the hollow bulk magnet 11 is made superconducting. At this time, a predetermined magnetic flux remains linked to the bulk magnet 11. Hollow bulk magnet 11
When the magnetic field generation coil 21 is gradually demagnetized at the time when is in the superconducting state, the hollow bulk magnet in the superconducting state is
An electric current flows in the direction in which the flux linkage is kept constant. After the magnetic field generating coil 21 is completely demagnetized, the permanent current shown in FIG. 3 flows through the hollow bulk magnet 11 so as to generate a predetermined magnetic field.

Demagnetization of a high-temperature superconducting bulk magnet in which a persistent current flows is carried out in a procedure almost opposite to that in exciting. That is, when the magnetic field generating coil 21 is excited in the negative direction, the current flowing through the hollow bulk magnet 11 becomes smaller according to the strength of the magnetic flux generated by the magnetic field generating coil 21. Bulk magnet 11
Magnetic field generating coil 21 when the current flowing through the coil becomes zero
The current is maintained and the heater 31 is struck to make the bulk magnet 11 have a normal conductivity. After that, if the current of the magnetic field generating coil 21 is gradually reduced to zero, no current flows in the bulk magnet 11.

If a superconductor is used for the magnetic field generating coil 21, the hollow bulk magnet 11 can be excited up to a high magnetic field.

When the high temperature superconducting bulk magnet is demagnetized, it is not necessary to make the entire hollow bulk magnet 11 normal conductive. It is sufficient that at least a part of the hollow bulk magnet 11 is in the normal conducting state and the magnetic flux in the loop of the bulk magnet 11 can freely move to the outside. That is, the heater 3 used for normal conduction
1 may be installed in a part of the bulk magnet. For example, as shown in FIG. 4, it may have a shape surrounding a part of the hollow bulk magnet 11, and in order to improve the response to normal conductivity, as shown in FIG. You may install 33 grade | etc.,. If the current flowing through the heaters 31, 32 and the like is pulsed, the superconducting state and the normal conducting state can be switched more quickly.

Further, the superconducting bulk magnet may be made to have a normal conductivity by using an external magnetic field and applying a magnetic field higher than the critical magnetic field. In this case, an external magnetic field generating coil 51 is installed adjacent to the hollow bulk magnet 11 as shown in FIG. When the hollow bulk magnet 11 is made to have normal conductivity, the external magnetic field generating coil 51 is excited so that a magnetic field higher than the critical magnetic field acts on a part of the bulk magnet. At this time, if a pulsed magnetic field is used as the external magnetic field, the bulk magnet can be rapidly made normal. Further, if an even number of external magnetic field generating coils 51, 52 and the like are installed at the target positions so as to generate mutually opposite magnetic fields, it is possible to eliminate the influence on the magnetic field generated by the magnetic field generating coil 21. If a normal conductor is used for the external magnetic field coils 51, 52, etc., a pulsed magnetic field can be applied at high speed.

FIG. 7 shows a seventh embodiment. The excitation / demagnetization device includes a hollow bulk magnet 11 and a magnetic field generation coil 21, and the hollow bulk magnet 11 includes the magnetic field generation coil 21.
The magnetic field generated by the makes it normal. When the hollow bulk magnet 11 is made to have normal conductivity, the magnetic field generating coil 2 is generated until a magnetic field higher than the critical magnetic field is generated at the position of the hollow bulk magnet 11.
It is necessary to increase the current of 1. At the time of excitation, the current of the magnetic field generating coil 21 is increased until the hollow bulk magnet 11 is in the normal conducting state, so that a predetermined magnetic field is generated while the hollow bulk magnet 11 is in the normal conducting state. 21
Set the current of. After the hollow bulk magnet 11 is brought into the superconducting state, the current of the magnetic field generating coil 21 is gradually reduced to flow a predetermined permanent current through the hollow bulk magnet 11. At the time of degaussing, the current of the magnetic field generating coil 21 is increased in the negative direction to make the current of the hollow bulk magnet zero, and then the hollow bulk magnet 11 is made to be in the normal conducting state, while the hollow bulk magnet is in the normal conducting state. The current of the generating coil 21 is made zero. Since it is not necessary to raise the temperature of the bulk magnet 11 when the hollow bulk magnet 11 is made to have normal conductivity by using an external magnetic field, superconductivity and normal conduction can be switched quickly.

FIG. 8 shows an eighth embodiment. A pipe 61 for a high-temperature refrigerant is provided adjacent to the hollow bulk magnet 11, and the high-temperature refrigerant is sprayed to make the hollow bulk magnet 11 a normal conductor. In this example, it is possible to cool the bulk magnet by using the low-temperature refrigerant even when it is made superconducting, so that the bulk magnet can be made superconducting quickly.

In the embodiment shown in FIG. 9, high-temperature refrigerant pipes 62, 63, etc. are passed through the bulk magnet to improve the response characteristics of normal conduction and superconductivity.

FIG. 10 shows a tenth embodiment. A magnetic body 71 is provided near the hollow bulk magnet 11. After exciting the magnetic field generating coil 21, the magnetic material 71 is brought closer to increase the magnetic flux density in the vicinity of the hollow bulk magnet 11 to a critical magnetic field or more. Thereby the bulk magnet 11
Normalize.

As described above, if the high temperature superconducting bulk magnet is made to have normal conductivity by using the magnetic material, it is not necessary to supply an extra current to the demagnetizing device, so that the temperature rise of the refrigerant and the superconductor can be reduced. Therefore, superconductivity and normal conduction can be quickly achieved.

FIG. 11 shows an eleventh embodiment. In the embodiment, the magnetomotive force of each magnet is set so that the magnetic flux on the straight line 91 distant from the surface of the eight superconducting bulk magnets arranged in a line has a sinusoidal distribution. That is, as shown in FIG.
The magnetic flux density of the superconducting bulk magnet 11 is 101
Then, a current is applied to the superconducting magnets 11, 12, 13 and so on so that the magnetic flux density produced by the superconducting bulk magnet 12 becomes 102. As a result, the spatial magnetic flux density on the line segment a-b has a sinusoidal distribution. In order to obtain such a magnetic flux density distribution, the magnetomotive force of the exciting magnetic field generating coil may be changed when exciting the superconducting magnet. As shown in FIG. 13, the superconducting coils 11, 12, 13 and the like are magnetic field generating coils 21, 22, 23.
, Etc., the magnetomotive force of the magnetic field generating coil 21 is determined by the magnetic flux density 101 of the superconducting coil 11, and similarly, the magnetomotive force of the magnetic field generating coils 22, 23, etc., depends on the magnetic flux density 102, 103, etc. Decide To change the magnetomotive force, change the current or the number of turns of the magnetic field generating coil. An example of use of the above-mentioned excitation method is a magnetic levitation transfer device. If the magnetic field generated by the superconducting magnet provided in the magnetic levitation transportation vehicle is distributed in a sinusoidal shape at the position of the levitation coil installed on the ground side facing the superconducting magnet, the transportation device will travel. The induced current generated in the ground coil becomes sinusoidal, and the generation of the harmonic magnetic flux is suppressed, so that the trouble due to the harmonic magnetic flux can be prevented. Further, it is also possible to make the magnetic flux distribution generated by the superconducting magnet device rectangular and use it by changing the pitch of N and S.

When the superconducting bulk magnets 11, 12, 112, 122, etc. are arranged and used on a large number of planes as shown in FIG. 14, when the magnets in the normal conducting state are switched to the superconducting state during excitation, the magnets May cause a time delay. For example, when only the bulk magnet 122 is made superconducting, the magnetic flux that has been linked to the inside of the conductor of the bulk magnet 122 until then is located in the hollow portion of the bulk magnet 122 or the surrounding bulk magnets 12, 112 in the normal conducting state. Is rejected by. As a result, it is conceivable that the number of interlinkage magnetic fluxes of the bulk magnets 12, 112 and the like increases and the magnetic field generated by the entire magnet device loses symmetry. To reduce this effect, adjust the time to turn off the heater provided in each superconducting magnet,
Superconductivity is gradually changed from the central magnet to the outer magnet,
Magnets 12, 15, 1 symmetrically positioned with respect to the center of the device
The heaters such as 23 and 153 may be turned off at the same time. If the outer magnets are made superconducting one after another, the repulsed magnetic flux gathers in the central direction, so the central magnet has a higher magnetic flux density, and the outer magnets have a lower magnetic flux density. The magnetic flux distribution on a straight line separated by a predetermined distance becomes sinusoidal. Furthermore, if the cooling system is set so that when the bulk magnet becomes superconducting, the outer peripheral portion of each magnet always becomes superconducting. The influence on the flux linkage is small. Further, by increasing or decreasing the current of the magnetic field generating coil, the influence of magnetic field rejection during superconductivity may be reduced.

[0025]

According to the present invention, the high temperature superconducting bulk magnet can be easily demagnetized in a short time.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an excitation / demagnetization device for a superconducting bulk magnet of the present invention.

FIG. 2 is a schematic diagram showing a state of magnetic flux lines of a hollow bulk magnet showing an embodiment of the present invention.

FIG. 3 is a principle diagram showing a permanent current flowing through a hollow bulk magnet according to another embodiment of the present invention.

FIG. 4 is an installation view of a heater showing another embodiment of the present invention.

FIG. 5 is an installation view of a heater showing another embodiment of the present invention.

FIG. 6 is an installation diagram of an external magnetic field coil showing another embodiment of the present invention.

FIG. 7 is a configuration diagram showing a state in which an external magnetic field is generated by a magnetic field generating coil according to another embodiment of the present invention.

FIG. 8 is a pipe installation diagram for a high temperature refrigerant showing another embodiment of the present invention.

FIG. 9 is a pipe installation view for a high temperature refrigerant showing another embodiment of the present invention.

FIG. 10 is an installation view of a magnetic body showing another embodiment of the present invention.

FIG. 11 is a configuration diagram showing an excitation method using a plurality of bulk magnets according to another embodiment of the present invention.

FIG. 12 is a configuration diagram showing a magnetic flux density distribution on a straight line showing another embodiment of the present invention.

FIG. 13 is a layout view of a plurality of bulk magnets and a magnetic field generating coil showing another embodiment of the present invention.

FIG. 14 is a layout view of a plurality of bulk magnets showing another embodiment of the present invention.

[Explanation of symbols]

11,112,113,12,122,123,13,
132, 133, 14, 142, 143, 15, 15
2, 153, 16, 162, 163 ... Hollow bulk magnet,
21, 22, 23, 24, 25 ... Magnetic field generating coils, 3
1, 32, 33, 34, 35 ... Heater, 41 ... Magnetic flux, 5
1, 52 ... External magnetic field generating coils, 61, 62, 63, 6
4 ... Pipe for high temperature refrigerant, 71 ... Magnetic material, 81 ... Yoke,
91 ... Straight line, 101, 102, 103, 104, 105
… The magnetic flux density generated by the superconducting magnet.

Front page continuation (72) Inventor Tokuaki Hino 7-1-1 Omika-cho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Naoki Maki 7-1-1 Omika-cho, Hitachi City, Ibaraki Hitachi, Ltd., Hitachi Research Laboratory

Claims (15)

[Claims] 1. A high-temperature superconducting bulk comprising: a hollow bulk magnet; a magnetic field generating coil installed so as to face the hollow bulk magnet; and a device for normalizing a part or the whole of the hollow bulk magnet. Magnet demagnetization device. 2. A high temperature superconducting bulk comprising: a hollow bulk magnet; a magnetic field generating coil installed so as to face the hollow bulk magnet; and a heater for normalizing a part or the whole of the hollow bulk magnet. Magnet demagnetization device. 3. A hollow bulk magnet, a magnetic field generating coil installed so as to face the hollow bulk magnet, and an external magnetic field generator for normalizing a part or the whole of the hollow bulk magnet. Excitation / demagnetization device for high temperature superconducting bulk magnets. 4. An excitation / demagnetization device for a high temperature superconducting bulk magnet, wherein the heater according to claim 2 is a pulse heating device. 5. An excitation / demagnetization device for a high temperature superconducting bulk magnet, wherein the external magnetic field generating device according to claim 3 is a pulse heating device. 6. An excitation / demagnetization device for a high temperature superconducting bulk magnet, wherein the external magnetic field generation device according to claim 3 is a magnetic field generation coil. 7. An exciter / demagnetizer for a high temperature superconducting bulk magnet, wherein the external magnetic field generator according to claim 3 is a magnetic material. 8. An excitation / demagnetization device for a high temperature superconducting bulk magnet, wherein the device for converting to normal conductivity according to claim 1 uses a high temperature refrigerant. 9. An apparatus for demagnetizing a high-temperature superconducting bulk magnet, wherein the high-temperature refrigerant according to claim 8 is sprayed onto the high-temperature superconducting bulk magnet for a short time. 10. An apparatus for demagnetizing a high temperature superconducting bulk magnet, wherein the magnetic field generating coil according to any one of claims 1 to 3 is a superconducting coil. 11. An excitation / demagnetization device for a high temperature superconducting bulk magnet, wherein an even number of the external magnetic field generating coils according to claim 6 are arranged at target positions. 12. A high temperature superconducting device comprising: an exciting step of exciting a magnetic field generating coil to a predetermined magnetic field; a normalizing step of normalizing a hollow bulk magnet; and a degaussing step of demagnetizing a magnetic field generating coil. Excitation / demagnetization method for bulk magnets. 13. A high temperature superconducting bulk characterized in that each hollow bulk magnet is excited so that a magnetic flux density on a straight line at a constant distance has a predetermined distribution from the hollow bulk magnet in which a plurality of superconducting magnet devices are arranged. How to demagnetize a magnet. 14. The high temperature superconducting bulk magnet according to claim 13, wherein each hollow bulk magnet is excited so that the magnetic flux density on a straight line at a predetermined distance from the plane is distributed in a sinusoidal shape. Method. 15. A high temperature characterized by exciting and demagnetizing one superconducting magnet device of a plurality of hollow bulk magnets to simultaneously superconduct or normalize a plurality of bulk magnets arranged at target positions. Excitation / demagnetization method of superconducting bulk magnet.