JP2010147370A - Electromagnet device - Google Patents

Abstract

Provided is an electromagnet device that can quickly attenuate a current flowing through a high-temperature superconducting coil when a normal conduction transition occurs in a part of the high-temperature superconducting coil during a permanent current operation.
A current limiter 5 connected in series to a high temperature superconducting coil 3 and using a low temperature superconducting wire whose critical temperature is lower than that of the high temperature superconducting coil 3, and connected in parallel to the high temperature superconducting coil 3. And the current limiter 5 is superconductive by energizing the temperature raising means 6 with a voltage generated by a part of the high-temperature superconducting coil 3 being switched from the superconducting state to the normal conducting state. Transition from state to normal conduction.
[Selection] Figure 1

Description

  The present invention relates to an electromagnet device provided with a superconducting coil, and more particularly to protection of a superconducting coil during quenching.

  The basic circuit of an electromagnet device having a conventional superconducting coil includes a superconducting coil, an exciting power supply for supplying current to the superconducting coil, a permanent current switch that forms a closed circuit for permanent current operation, and a superconducting coil. It consists of protective resistors connected in parallel. In such an electromagnet device, a current is supplied from the excitation power source to the superconducting coil with the permanent current switch open (off), and then the permanent current switch is closed (on) and the supply current from the excitation power source is supplied. As a result, it is possible to perform a permanent current operation in which the current continues to flow in the superconducting closed circuit including the superconducting coil and the permanent current switch with almost no attenuation. According to the permanent current operation, the electromagnet device can hold the magnetic field without consuming electric power for a long time (see, for example, Patent Document 1).

  When a part of the superconducting coil changes from the superconducting state to the normal conducting state during permanent current operation and resistance is generated, the energy stored in the superconducting coil is converted into thermal energy by Joule heating, and the temperature of the superconducting coil rises. . This temperature rise causes the part of the surrounding superconducting coils to further transition from the superconducting state to the normal conducting state. Finally, the normal conducting transition causes a quenching phenomenon that spreads over the entire superconducting coil. Although the superconducting coil can retain a large amount of stored energy, if this stored energy is converted into thermal energy by the quenching phenomenon, the superconducting coil may cause an excessive temperature rise, resulting in performance deterioration or even burning.

Therefore, in the conventional electromagnet device, the voltage generated at both ends of the superconducting coil due to the resistance generated in the superconducting coil due to the normal conducting transition is applied to the protective resistor, and the current flows through the protective resistor, so that not only the superconducting coil, Even in the protective resistance, the stored energy is consumed by Joule heat generation, and the temperature rise of the superconducting coil is suppressed.
Japanese Patent Laid-Open No. 5-190325 (first term, FIG. 1)

So-called high-temperature superconducting coils using magnesium diboride (MgB ₂ ) or oxide superconducting materials are compared with so-called low-temperature superconducting coils using niobium titanium (Nb ₃ Ti) or niobium tin (Nb ₃ Sn). Since the critical temperature is high and the temperature difference from the easily settable cooling temperature, for example, the cooling temperature 20K, can be made large, the normal conduction transition from the superconducting state is difficult, and the occurrence of the quenching phenomenon is suppressed from the low temperature superconducting coil. it can.

  Consider the case where a quench phenomenon occurs in the high-temperature superconducting coil from the viewpoint of fail-safe. Considering the process in which the quench phenomenon occurs, first, in a part of the high-temperature superconducting coil, a transition from the superconducting state to the normal conducting state is made. However, the high-temperature superconducting coil is difficult to make a normal conduction transition, and some high-temperature superconducting coils around the normal conduction transition are less likely to make a normal conduction transition. Slows down. For this reason, a part of the high-temperature superconducting coil undergoing the normal conduction transition locally generates heat for a long time. In addition, only a part of the normal superconducting transition of the high-temperature superconducting coil has a small resistance generated in the high-temperature superconducting coil and a small voltage generated at both ends of the high-temperature superconducting coil. Can not be consumed. As a result, high-temperature superconducting coils must consume most of the stored energy in a part of their normal conduction region, and are subject to thermal distortion due to local temperature rise, and are thought to burn out when the temperature rises further. It was.

  As described above, when a normal conduction transition occurs in a part of the high-temperature superconducting coil during permanent current operation, the current flowing through the high-temperature superconducting coil is quickly attenuated, and the temperature of a part of the high-temperature superconducting coil rises locally. It is necessary to suppress this.

  Accordingly, an object of the present invention is to provide an electromagnet device capable of quickly attenuating a current flowing through a high-temperature superconducting coil when a normal conducting transition occurs in a part of the high-temperature superconducting coil during permanent current operation. It is in.

In order to achieve the above object, an electromagnet device of the present invention is connected in series to a superconducting coil, and is connected in parallel to the current limiting device using a superconducting wire whose critical temperature is lower than that of the superconducting coil, A temperature raising means for raising the temperature of the current limiting device by energization,
The current limiter is changed from the superconducting state to the normal conducting state by energizing the temperature raising means with a voltage generated by a part of the superconducting coil being changed from the superconducting state to the normal conducting state.

  ADVANTAGE OF THE INVENTION According to this invention, when a normal conduction transition generate | occur | produces in a part of high temperature superconducting coil in permanent current driving | operation, the electromagnet apparatus which can rapidly attenuate the electric current which flows through a high temperature superconducting coil can be provided. .

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 shows a circuit diagram of an electromagnet device 1 according to a first embodiment of the present invention. The electromagnet device 1 has a cryostat 2. An excitation power source 10 and a current breaker 11 connected in series to the excitation power source 10 are provided outside the cryostat 2. Inside the cryostat 2 are a permanent current switch 4, a plurality (two in FIG. 1) of protective resistors 7 (7a, 7b), and a plurality (two in FIG. 1) of high-temperature superconducting coils 3 (3a, 3b). A plurality (two in FIG. 1) of current limiting devices 5 (5a, 5b) and a plurality (two in FIG. 1) of temperature raising means 6 are provided and kept cold. In particular, the high-temperature superconducting coil 3, the permanent current switch 4, and the current limiter 5 are kept in a superconducting state by being kept below the critical temperature of the superconducting material possessed by the cryostat 2.

  The permanent current switch 4 has an excitation power source 10 connected to one end and a current breaker 11 connected to the other end.

  The protective resistor 7a and the protective resistor 7b are connected in series, the excitation power supply 10 is connected to one end of the series connection, and the current breaker 11 is connected to the other end of the series connection.

  The current limiter 5a and the high temperature superconducting coil 3a are connected in series, and both ends of the series connection are connected to both ends of the protective resistor 7a, so that the series connection is connected in parallel to the protective resistor 7a. Similarly, the current limiter 5b and the high temperature superconducting coil 3b are connected in series, and both ends of the series connection are connected to both ends of the protective resistor 7b, so that the series connection is connected in parallel to the protective resistor 7b.

The high-temperature superconducting coil 3 is formed by winding a superconducting wire in which the periphery and gaps of a plurality of superconductors are covered and filled with a cooling stabilizer around a winding frame or the like. As the superconductor, a so-called high-temperature superconducting material such as magnesium diboride (MgB ₂ ) or an oxide superconducting material is used. As the cooling stabilizer, oxygen-free copper (pure copper: Cu) having a low electrical resistivity and high thermal conductivity is used.

The current limiter 5 has a superconducting wire in which the periphery and gaps of a plurality of superconductors are covered and filled with a cooling stabilizer. As the superconductor, a so-called low-temperature superconducting material such as niobium titanium (NbTi) or niobium 3 tin (Nb ₃ Sn) having a lower critical temperature than the high-temperature superconducting material is used. As the cooling stabilizer, a metal having a higher electrical resistivity than oxygen-free copper, for example, a copper nickel alloy is used. The current limiter 5 is wound non-inductively so as not to be magnetically coupled to the high temperature superconducting coil 3.

  Each of the two temperature raising means 6 has a heater 9 (9a, 9b) and a pair of diodes 8 (8a, 8b) connected in parallel with different forward and reverse directions. The heater 9a and the diode 8a are connected in series, and both ends of this series connection are connected to both ends of the high temperature superconducting coil 3a, so that this series connection (temperature raising means 6) is connected in parallel to the high temperature superconducting coil 3a. Similarly, the heater 9b and the diode 8b are connected in series, and both ends of this series connection are connected to both ends of the high temperature superconducting coil 3b, so that this series connection (temperature raising means 6) is connected in parallel to the high temperature superconducting coil 3b. ing. The heater 9 is thermally connected (contacted) with the current limiting device 5, particularly a superconducting wire of the current limiting device 5 to be described later, and the heat generated by the heater 9 is conducted to the superconducting wire of the current limiting device 5 (heat transfer). ). Thereby, the temperature raising means 6 can raise the temperature of the superconducting wire of the current limiter 5 by energization.

  Next, the operation of the electromagnet device 1 will be described. First, the high-temperature superconducting coil 3, the permanent current switch 4, and the current limiter 5 in the cryostat 2 are kept below the critical temperature and maintained in the superconducting state. Next, with the permanent current switch 4 opened (off), the current breaker 11 is closed (on), and current is supplied from the excitation power supply 10 to the high temperature superconducting coil 3. Thereafter, the permanent current switch 4 is closed (ON), and further, after the current supply is stopped, the current breaker 11 is opened (OFF). As a result, no current is supplied from the exciting power source 10 to the high temperature superconducting coil 3, but the two high temperature superconducting coils 3, the two current limiters 5, and the closed permanent current switch 4 are connected in series. The current continues to flow in the closed circuit with almost no attenuation in the superconducting state, and the electromagnet apparatus 1 is in a permanent current operation. In the permanent current operation, the electromagnet device 1 can hold the magnetic field for a long time without supplying power from the excitation power supply 10.

Next, a case where a part of one high temperature superconducting coil 3a of the two high temperature superconducting coils 3 undergoes a normal conducting transition from the superconducting state during the permanent current operation of the electromagnet device 1 will be described.
When a normal conduction transition occurs in a part of the high-temperature superconducting coil 3a and the voltage across the high-temperature superconducting coil 3a exceeds the on-voltage of the diode 8a, the diode 8a is closed (on) and the temperature raising means 6 is energized. . A part of the current flowing through the closed circuit passing through the high temperature superconducting coil 3a and the permanent current switch 4 is supplied to the heater 9a, and the heater 9a generates heat. The heat of the heater 9a is conducted to the current limiting device 5a, and heats the current limiting device 5a, particularly a superconducting wire formed of a low temperature superconducting material. By this heating, the temperature of the superconducting wire is raised, a part of the superconducting wire is changed from the superconducting state to the normal conducting state, and heat is generated in part of the superconducting wire. The normal conduction transition and the heat generation propagate in the avalanche form throughout the superconducting wire. The critical temperature of the low-temperature superconducting material is lower than that of the high-temperature superconducting material, and the low-temperature superconducting material is more likely to undergo normal conduction transition than the high-temperature superconducting material, so that the propagation speed is faster than the propagation speed in the high-temperature superconducting coil 3a. Further, since the electrical resistivity of the cooling stabilizer of the current limiting device 5a is higher than the electrical resistivity of the cooling stabilizer of the high temperature superconducting coil 3a, the normal conduction transition occurs in a part of the superconductor, and the normal conduction Even if the current path changes from a part of the superconductor thus transferred to the cooling stabilizer around the superconductor, heat can be generated at a high energy density in the cooling stabilizer. As a result, the propagation speed of the normal conduction transition in the current limiter 5a is faster than the propagation speed in the high-temperature superconducting coil 3a.

  As a result, a large resistance is quickly generated in the current limiter 5a, and a large current flowing through the high-temperature superconducting coil 3a connected in series with the current limiter 5a quickly flows into the current limiter 5a. In the flow device 5a, when the large current flows, heat is generated and the stored energy can be consumed quickly.

  Also, if a large current flows quickly through the high-resistance current limiter 5a, a high voltage is generated quickly at both ends of the current limiter 5a. This high voltage is quickly applied to the protective resistor 7a. As a result, a current flows quickly through the protective resistor 7a so as to satisfy Ohm's law. Since the current flows quickly through the protective resistor 7a, the protective resistor 7a quickly generates heat, and the protective resistor 7a can quickly consume the stored energy.

  Furthermore, when a high voltage is quickly applied to the protective resistor 7a, a high voltage is also quickly applied to the protective resistor 7b. This is because the protective resistor 7a and the protective resistor 7b are connected in series, and both ends of the series connection are short-circuited by the permanent current switch 4 in the closed (on) state, so that the potential difference becomes zero. When a high voltage is applied to the protective resistor 7a, the positive and negative values are reversed and equal in magnitude to the protective resistor 7b compared to the high voltage applied to the protective resistor 7a so as to satisfy the relationship of zero potential difference. A voltage is applied. This also causes a current to flow quickly through the protective resistor 7b so as to satisfy Ohm's law. Since the current flows quickly through the protective resistor 7b, the protective resistor 7b quickly generates heat, and the protective resistor 7b can also quickly consume the stored energy.

  Thus, when a normal conducting transition occurs in a part of the high-temperature superconducting coil 3a, the current limiting device 5a quickly increases in resistance and generates heat, not only quickly consuming stored energy but also quickly protecting it. Even when a current is passed through the resistor 7a and the protective resistor 7b, the stored energy is quickly consumed. A part of the high-temperature superconducting coil 3a subjected to normal conduction transition can suppress heat generation by quickly consuming the stored energy, and can prevent performance deterioration and burning of the high-temperature superconducting coil 3a. .

(Second Embodiment)
In FIG. 2, the circuit diagram of the electromagnet apparatus 1 which concerns on the 2nd Embodiment of this invention is shown. The electromagnet device 1 of the second embodiment is different from the electromagnet device 1 of the first embodiment in that the temperature raising means 6 is a circuit for connecting the current limiter 5 to the high temperature superconducting coil 3 in series and in parallel. Thus, the heater 9 is omitted. The resistor 13 connected in series with the diode 8 can limit the current flowing through the temperature raising means 6 and further the current limiter 5 and protect the temperature raising means 6 and the current limiter 5.

  FIG. 3 shows a cross-sectional view of the superconducting wire 20 included in the current limiting device 5 provided with the wiring constituting the temperature raising means 6. This cross-sectional view shows a cross section of the superconducting wire 20 cut in the length direction, not in the width direction. In the superconducting wire 20, the periphery of the plurality of superconductors 22 is covered with the cooling stabilizer 21, and the gaps between the plurality of superconductors 22 are filled with the cooling stabilizer 21. One end of the high-temperature superconducting coil 3 and the cooling stabilizer 21 are connected by wiring. In addition, one end of the diode 8 and the cooling stabilizer 21 are connected by wiring. With these connections, the cooling stabilizer 21 of the current limiter 5 is connected in parallel to the high temperature superconducting coil 3. On the cooling stabilizer 21, the connection points of the parallel connection wires are separated from each other. The cooling stabilizer 21 connected by these wires functions as the heater 9. Since the cooling stabilizer 21 is thermally connected to the superconductor 22, the heat generated by the cooling stabilizer 21 can be reliably conducted to the superconductor 22. For this reason, according to the second embodiment, not only the same effect as in the first embodiment can be obtained, but also the current limiter 5 can be heated more quickly.

(Third embodiment)
FIG. 4A shows a circuit diagram of an electromagnet device according to the third embodiment of the present invention. The electromagnet device 1 of the third embodiment is different from the electromagnet device 1 of the second embodiment in that it has a plurality of resistors 14 (14a, 14b) connected in series, and the plurality of resistors 14 (14a). 14b) is connected in parallel to the series connection of the plurality of high-temperature superconducting coil groups 12 (12a, 12b), and a connection point 16 between the plurality of resistors 14a, 14b connected in series, The temperature riser 6 is connected between the connection points 15 between the plurality of high temperature superconducting coil groups 12a and 12b connected in series to form a bridge circuit (balanced circuit). The plurality of high-temperature superconducting coils 3 is divided into two by high-temperature superconducting coil groups 12a and 12b.

  FIG. 4B shows an equivalent circuit diagram of the bridge circuit (balanced circuit). Note that, in the equivalent circuit diagram, the connection of the temperature raising means 6 to the current limiters 5a and 5b is depicted, and the connection to the current limiters 5a and 5b is the cooling stability of the current limiters 5a and 5b. The cooling stabilization material 21 is made to function as the heater 9. On the other hand, in FIG. 4A, the current limiters 5a and 5b are connected in series to the high-temperature superconducting coil groups 12a and 12b, but in the superconducting state, the current limiters 5a and 5b are non-inductive and non-resistance. 4B, the series connection of the current limiters 5a and 5b to the high temperature superconducting coil groups 12a and 12b is omitted.

  In the superconducting state, the ratio La / Lb of the inductance La of the high temperature superconducting coil group 12a and the inductance Lb of the high temperature superconducting coil group 12b is equal to the ratio Ra / Rb of the resistance value Ra of the resistor 14a and the resistance value Rb of the resistor 14b (La / Lb = Ra / Rb), and the bridge circuit satisfies the equilibrium condition. For this reason, in the superconducting state, the potential difference between the connection point 15 and the connection point 16 becomes zero, and no current flows through the current limiters 5a and 5b.

  When a part of the high-temperature superconducting coil group 12a or the high-temperature superconducting coil group 12b transitions from the superconducting state to the normal conducting state, the equilibrium condition is not satisfied by the resistance component generated thereby, and the connection between the connection point 15 and the connection point 16 is quickly achieved. A potential difference occurs, and the current limiters 5a and 5b are quickly energized. And current limiting device 5a, 5b can be heated up quickly, and resistance can be raised. Thereby, the same effect as that of the first embodiment can be obtained also in the third embodiment.

  Even when the current of the high-temperature superconducting coil 3 is swept with the permanent current switch 4 opened, the magnitudes of the induced voltages generated in the high-temperature superconducting coil groups 12a and 12b are equal and the equilibrium condition is satisfied. Therefore, the potential difference between the connection point 15 and the connection point 16 becomes zero, and current can be prevented from flowing through the temperature raising means 6 and the current limiters 5a and 5b. As a result, unlike the first embodiment and the second embodiment, it is not necessary to provide the diode 8 (see FIG. 1) in the temperature raising means 6. The protective resistor 7 is connected in parallel to the series connection of the plurality of high temperature superconducting coil groups 12a and 12b and the plurality of current limiting devices 5a and 5b.

(Fourth embodiment)
In FIG. 5, the circuit diagram of the electromagnet apparatus 1 which concerns on the 4th Embodiment of this invention is shown. The circuit configuration of the electromagnet device 1 of the fourth embodiment is the same as the circuit configuration of the electromagnet device 1 of the second embodiment. As shown in FIG. 5, the cryostat 2 includes a vacuum container 17 for vacuum insulation, a radiation shield 18 that suppresses intrusion of radiant heat, a refrigerator 19, and a heat transfer means 25. The radiation shield 18 is included in the vacuum container 17, and the heat transfer means 25 is included in the radiation shield 18. The refrigerator 19 has a first stage that can be cooled to an extremely low temperature, and a second stage that can be cooled to a low temperature although the temperature is higher than that of the first stage. The first stage is thermally connected to the heat transfer means 25, and the heat transfer means 25 is cooled to the cryogenic temperature. The second stage is thermally connected to the radiation shield 18, and the radiation shield 18 is cooled to a low temperature that is higher than the cryogenic temperature. The heat transfer means 25 includes a high-temperature superconducting coil 3 (3a, 3b), a protective resistor 7 (7a, 7b), a permanent current switch 4, a current limiter 5 (5a, 5b), and a diode 8 included in the radiation shield 18. (8a, 8b), the resistor 13 (temperature raising means 6) are thermally connected to each other, cooled to below the critical temperature, the high-temperature superconducting coil 3 (3a, 3b), the permanent current switch 4, the current limiter 5 (5a, 5b) can be kept in a superconducting state. According to the fourth embodiment, not only the same effects as those of the second embodiment can be obtained, but the high-temperature superconducting coil 3 (3a) can be obtained without preparing a refrigerant container and a refrigerant contained in the radiation shield 18 separately. 3b), the permanent current switch 4 and the current limiter 5 (5a, 5b) can be kept below the critical temperature to maintain the superconducting state, and the electromagnet device 1 can be operated.

(Fifth embodiment)
In FIG. 6, the circuit diagram of the electromagnet apparatus 1 which concerns on the 5th Embodiment of this invention is shown. The circuit configuration of the electromagnet device 1 of the fifth embodiment is the same as the circuit configuration of the electromagnet device 1 of the second and fourth embodiments. The electromagnet device 1 according to the fifth embodiment is different from the electromagnet device 1 according to the fourth embodiment in that the electromagnet device 1 includes a refrigerant container 27 into which the refrigerant 26 is placed instead of the heat transfer means 25. The refrigerant container 27 is included in the vacuum container 17 and the radiation shield 18. The refrigerant container 27 is thermally connected to the first stage of the refrigerator 19, and the refrigerant container 27 and the refrigerant 26 are cooled to the cryogenic temperature. The refrigerant container 27 contains the permanent current switch 4, the current limiter 5 (5a, 5b), the diode 8 (8a, 8b), and the resistor 13 (temperature raising means 6) together with the refrigerant 26, each of which is critical. It is possible to keep the permanent current switch 4 and the current limiter 5 (5a, 5b) in a superconducting state by cooling to below the temperature. As the refrigerant 26, liquid helium (He) can be used.

  The high-temperature superconducting coil 3 (3a, 3b) and the protective resistor 7 (7a, 7b) are enclosed in the vacuum vessel 17 and the radiation shield 18 and arranged outside the refrigerant vessel 27. The heat transfer means 28 is included in the vacuum vessel 17 and the radiation shield 18 and thermally connects the refrigerant vessel 27 and the high-temperature superconducting coil 3 (3a, 3b). Thereby, the high temperature superconducting coil 3 (3a, 3b) is cooled below the critical temperature and kept in the superconducting state. According to the fifth embodiment, not only the same effect as the second embodiment can be obtained, but also compared with the case where all the inclusions of the cryostat 2 except the radiation shield 18 are cooled by the refrigerant 26, The refrigerant container 27 can be made small, and the electromagnet device 1 can be operated with a small amount of the refrigerant 26.

(Sixth embodiment)
FIG. 7 shows a circuit diagram of an electromagnet device according to the sixth embodiment of the present invention. The circuit configuration of the electromagnet device 1 of the sixth embodiment is the same as the circuit configuration of the electromagnet device 1 of the second, fourth, and fifth embodiments. The electromagnet device 1 according to the sixth embodiment is different from the electromagnet device 1 according to the fifth embodiment in that the permanent current switch 4 is disposed outside the refrigerant container 27, and heat is supplied to the refrigerant container 27 by the heat transfer means 28. Are different in that they are connected together.

  The high-temperature superconducting coil 3 and the permanent current switch 4 are connected to the refrigerant container 27 by the heat transfer means 28, and are cooled by the heat conduction and kept below the critical temperature to maintain the superconducting state. This also allows the permanent current switch 4 to be cooled below the critical temperature and kept in the superconducting state. According to the sixth embodiment, not only the same effects as in the fifth embodiment can be obtained, but also the refrigerant container 27 can be further reduced in size, and the electromagnet device 1 is operated with a small number of refrigerants 26. It becomes possible.

1 is a circuit diagram of an electromagnet device according to a first embodiment of the present invention. It is a circuit diagram of the electromagnet apparatus which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the wire which the fault current limiter with which the wiring which comprises a temperature rising means was given. (A) is a circuit diagram of the electromagnet apparatus which concerns on the 3rd Embodiment of this invention, (b) is an equivalent circuit schematic of the bridge circuit which consists of a superconducting coil and a temperature rising means. It is a circuit diagram of the electromagnet apparatus which concerns on the 4th Embodiment of this invention. It is a circuit diagram of the electromagnet apparatus which concerns on the 5th Embodiment of this invention. It is a circuit diagram of the electromagnet apparatus which concerns on the 6th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electromagnet apparatus 2 Cryostat 3, 3a, 3b Superconducting coil 4 Permanent current switch 5, 5a, 5b Current limiting device 6 Temperature rising means 7, 7a, 7b Protection resistance 8, 8a, 8b Diode 9, 9a, 9b Heater 10 Excitation power supply DESCRIPTION OF SYMBOLS 11 Current breaker 12, 12a, 12b Superconducting coil group 13, 14, 14a, 14b Resistance 15 Connection point of superconducting coil group 16 Resistance connection point 17 Vacuum container 18 Radiation shield 19 Refrigerator 20 Superconducting wire material of current limiter 21 Cooling Stabilizer 22 Superconductor 26 Refrigerant 27 Refrigerant container 28 Heat transfer means

Claims (9)

A current limiter using a superconducting wire connected in series to the superconducting coil and having a critical temperature lower than that of the superconducting coil;
A heating means connected in parallel to the superconducting coil and heating the current limiter by energization;
An electromagnet apparatus characterized in that the current limiter changes from a superconducting state to a normal conducting state by energizing the temperature raising means with a voltage generated by a part of the superconducting coil changing from a superconducting state to a normal conducting state.   2. The electromagnet device according to claim 1, wherein a cooling stabilizer having a higher resistivity than pure copper is disposed around the superconductor of the superconducting wire in the current limiting device.   The electromagnet apparatus according to claim 1, wherein the temperature raising unit includes a heater that is in thermal contact with the superconducting wire of the current limiter.   4. The temperature raising means includes a circuit for connecting a cooling stabilizer disposed around the superconducting wire in parallel to the superconducting coil. The electromagnet device described in 1.   The electromagnet apparatus according to claim 1, wherein the temperature raising unit includes a diode. Having a plurality of resistors connected in series;
A plurality of the superconducting coils are connected in series,
The plurality of resistors are connected in parallel to the plurality of superconducting coils connected in series,
Connecting the temperature raising means between a plurality of connection points of the resistors and a plurality of connection points of the superconducting coils, to form a bridge circuit;
5. The bridge circuit according to any one of claims 1 to 4, wherein when a plurality of the superconducting coils are in a superconducting state, the bridge circuit satisfies an equilibrium condition and does not energize the temperature raising means. Electromagnet device. Heat transfer means contained in a vacuum vessel;
A refrigerator that is thermally connected to the heat transfer means and cools the heat transfer means;
The electromagnet device according to any one of claims 1 to 6, wherein the heat transfer means is thermally connected to the superconducting coil, the current limiter, and the temperature raising means. A refrigerant container contained in a vacuum container;
A refrigerator that is thermally connected to the refrigerant container and cools the refrigerant container and the refrigerant;
The electromagnet device according to any one of claims 1 to 6, wherein the refrigerant container contains the current limiter, the temperature raising unit, and the refrigerant. A heat transfer means enclosed in the vacuum vessel and thermally connected to the refrigerant vessel;
The electromagnet device according to claim 8, wherein the heat transfer means is thermally connected to the superconducting coil.

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