Superconducting device

Abstract

To provide a superconducting device capable of preventing damage to a diode for protecting a superconducting coil when a quench occurs.SOLUTION: A superconducting device 1 includes a superconducting coil 5 provided in a cryogenic region 9 for maintaining a superconducting state, a diode 6 that is connected to a power supply 4 in parallel with the superconducting coil 5 and bypasses the current flowing to the superconducting coil 5 when quench occurs in the superconducting coil 5, and temperature adjustment portions 7, 8 that adjust the temperature of the diode 6.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a superconducting device.

Background Art

[0002] Generally, a superconducting device includes a diode to protect a superconducting coil when the superconducting coil in excitation transitions to normal conduction. The phenomenon where the superconducting coil transitions to normal conduction is called a quench. The voltage when the forward current of the diode rapidly increases at extremely low temperatures, the so-called forward voltage Vf, is 10 to 20 V, which is very high compared to normal temperature. Conventionally, by utilizing this property and installing the diode in the extremely low temperature region, both protection when the superconducting coil quenches and suppression of heat generation due to resistance during excitation and demagnetization are achieved.

[0003] During excitation, by setting the excitation voltage of the superconducting coil to be smaller than the forward voltage Vf of the diode, current flows through the superconducting coil. On the other hand, when the superconducting coil quenches and the voltage across both ends of the superconducting coil reaches the forward voltage Vf, current starts to flow through the diode, the voltage of the superconducting coil is suppressed, and the superconducting coil is protected.

[0004] Note that for a diode cooled to extremely low temperatures, the carriers are extremely few, and the forward current of the diode does not increase much. Also, when a certain amount of current flows through the diode, the heat generation of the diode itself causes a rapid increase in carriers. Due to this, it is considered that the forward voltage Vf becomes high at extremely low temperatures.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In conventional superconducting devices, when a quench occurs in the superconducting coil and current flows through the diode, the high forward voltage Vf can place a high load on the diode, potentially damaging it.

[0007] Embodiments of the present invention have been made in consideration of these circumstances and aim to provide a superconducting device that can prevent damage to the diode protecting the superconducting coil when a quench occurs. [Means for solving the problem]

[0008] An embodiment of the present invention provides a superconducting device comprising: a superconducting coil provided in an extremely low-temperature region for maintaining a superconducting state; a diode connected in parallel with the superconducting coil to a power supply, which diverts the current flowing through the superconducting coil when a quench occurs in the superconducting coil; and a temperature control unit for adjusting the temperature of the diode. At least one of the temperature control units is an insulating unit that insulates the diode from the cryogenic region. . [Effects of the Invention]

[0009] Embodiments of the present invention provide a superconducting device that can prevent damage to a diode protecting a superconducting coil when a quench occurs. [Brief explanation of the drawing]

[0010] [Figure 1] A cross-sectional view showing a superconducting device according to the first embodiment. [Figure 2] A graph showing the relationship between the forward voltage of a diode and temperature. [Figure 3] A cross-sectional view showing a superconducting device according to the second embodiment. [Figure 4] A cross-sectional view showing a superconducting device according to the third embodiment. [Figure 5] A cross-sectional view showing a superconducting device according to the fourth embodiment. [Modes for carrying out the invention]

[0011] (First Embodiment) The embodiments of the superconducting device will be described in detail below with reference to the drawings. First, the first embodiment will be described using Figures 1 and 2.

[0012] Reference numeral 1 in Figure 1 denotes a superconducting device of the first embodiment. This superconducting device 1 comprises a vacuum vessel 2, a shield 3, a power supply 4, a superconducting coil 5, a diode 6, an insulating section 7, and a heater 8. The insulating section 7 and the heater 8 constitute the temperature control section of the first embodiment.

[0013] Vacuum container 2 is a container whose interior is evacuated to provide insulation from the outside. Shield 3 is housed inside vacuum container 2. Superconducting coil 5 is housed inside shield 3.

[0014] The shield 3 reduces thermal radiation from the outside (high-temperature area), and has an cryogenic region 9 inside to maintain the superconducting state of the superconducting coil 5. The superconducting coil 5 and the diode 6 are located in this cryogenic region 9.

[0015] Power supply 4 supplies power to the superconducting coil 5. This power supply 4 is located outside the vacuum vessel 2. Power lines 11 extending from power supply 4 into the vacuum vessel 2 are led to the cryogenic region 9 via high-temperature superconducting leads 12. These high-temperature superconducting leads 12 are made of high-temperature superconductor.

[0016] Diode 6 is connected in parallel with the superconducting coil 5 to the power supply 4 and is a protection circuit that diverts the current flowing through the superconducting coil 5 when a quench occurs in the superconducting coil 5. The lead wire 13 of diode 6 is connected to the power line 11 that connects the power supply 4 and the superconducting coil 5.

[0017] In the first embodiment, a diode 6 is provided in a heat insulation part 7 that is thermally insulated from the cryogenic region 9. That is, the heat insulation part 7 thermally insulates the diode 6 from the cryogenic region 9. By doing so, the diode 6 is thermally insulated from the cryogenic region 9 where the superconducting coil 5 is provided, and the temperature of the diode 6 can be made different from that of the cryogenic region 9.

[0018] Furthermore, a heater 8 for raising the temperature of the diode 6 is provided in the heat insulation part 7. By doing so, the temperature of the diode 6 can be raised higher than that of the cryogenic region 9. Note that the heater 8 is controlled by a control device (not shown). This control device controls the output of the heater 8 so that the diode 6 always has a constant temperature.

[0019] The temperature adjustment part composed of the heat insulation part 7 and the heater 8 adjusts the temperature of the diode 6. Also, the temperature adjustment part raises the temperature of the diode 6 higher than the temperature of the cryogenic region 9 in advance before a quench occurs in the superconducting coil 5. By doing so, when a quench occurs, a current can be immediately passed through the diode 6, and the current flowing through the superconducting coil 5 is bypassed, so the superconducting coil 5 can be protected. In particular, by controlling the heater 8, the temperature of the diode 6 can be adjusted, and the forward voltage Vf can be arbitrarily set.

[0020] The load applied to the diode 6 is represented by Vf×I (forward voltage × power supply current), and the higher the forward voltage Vf rises, the higher the load becomes. As shown in the graph of FIG. 2, it is known that the forward voltage Vf of the diode 6 has temperature characteristics, and as the temperature of the diode 6 increases, the carrier density increases and the forward voltage Vf decreases.

[0021] By increasing the temperature of the diode 6 and reducing the forward voltage Vf, the peak load applied to the diode 6 can be reduced, and damage to the diode 6 can be prevented. Further, when the forward voltage Vf is less than (hereinafter) the excitation voltage of the superconducting coil 5, excitation becomes impossible, so it is necessary to design it to be equal to or higher than (exceeding) the excitation voltage of the superconducting coil 5. Therefore, in the present embodiment, the soundness of the diode 6 is ensured by adjusting the temperature of the diode 6 and arbitrarily setting the forward voltage Vf. For example, when the temperature of the cryogenic region 9 is 4K, temperature adjustment is performed so that the temperature of the diode 6 becomes 20K or higher.

[0022] In the first embodiment, the heater 8 adjusts the temperature of the diode 6 and controls the forward voltage Vf of the diode 6. Therefore, when the superconducting coil 5 quenches, the peak load when the current bypasses the diode 6 is reduced, and damage to the diode 6 can be prevented.

[0023] For the material of the conducting wire 13, metals such as stainless steel, copper-nickel alloy, brass, or high-temperature superconductors are applied. In particular, the material and wire diameter of the conducting wire 13 are designed so that the amount of heat input from the diode 6 to the cryogenic region 9 through the conducting wire 13 is below a specific amount.

[0024] In other words, the material and wire diameter of the conducting wire 13 are designed so that the total amount of heat input to the entire cryogenic region 9, including the amount of heat input from the diode 6 to the cryogenic region 9 through the conducting wire 13, is below the amount of heat input that can keep the superconducting coil 5 in the superconducting state. For example, the amount of heat input from the diode 6 to the cryogenic region 9 through the conducting wire 13 is 1 / 10 or less of the total amount of heat input to the entire cryogenic region 9.

[0025] In this way, it becomes difficult for heat to be transmitted from the diode 6 to the cryogenic region 9 through the conducting wire 13, and the superconducting coil 5 can be kept in the superconducting state. For example, by restricting the amount of heat input from the diode 6 and the heat insulation part 7 to the superconducting coil 5, the temperature of the diode 6 can be adjusted while suppressing the influence of heat conduction to the superconducting coil 5.

[0026] Furthermore, because the conductor 13 is made of a high-temperature superconductor, the temperature of the diode 6 is increased, and even if the temperature of the conductor 13 is increased by that heat, the electrical resistance of the conductor 13 can be suppressed, and when a quench occurs in the superconducting coil 5, current can be immediately supplied to the diode 6.

[0027] (Second Embodiment) Next, a second embodiment will be described with reference to Figure 3. Note that components identical to those shown in the previously described embodiment are denoted by the same reference numerals, and redundant descriptions are omitted.

[0028] The superconducting device 1A of the second embodiment comprises a vacuum vessel 2, a shield 3, a power supply 4, a superconducting coil 5, a diode 6, a heat insulating section 7, and a thermal anchor 14. The heat insulating section 7 and the thermal anchor 14 constitute the temperature control section of the second embodiment.

[0029] The thermal anchor 14 is a component made of a predetermined metal such as aluminum or copper. This thermal anchor 14 transfers heat from outside the cryogenic region 9 to the diode 6. The thermal anchor 14 is composed of, for example, a predetermined wire, a sheet-like member, or a frame member.

[0030] The diode 6 and the heat insulating section 7 are located in the cryogenic region 9. Here, one end of the thermal anchor 14 is connected to the heat insulating section 7, and the other end is connected to the shield 3. The heat from the shield 3 is then transferred to the diode 6 via the thermal anchor 14. In this way, the temperature of the diode 6 can be raised above that of the cryogenic region 9 by the heat conducted from outside the cryogenic region 9.

[0031] In the second embodiment, by providing a thermal anchor 14, the temperature of the diode 6 can be adjusted and the forward voltage Vf can be set arbitrarily. For example, by adjusting the material and wire diameter of the thermal anchor 14, the temperature of the diode 6 can be adjusted and the forward voltage Vf can be set arbitrarily. This reduces the peak load on the diode 6 and prevents damage to the diode 6.

[0032] (Third embodiment) Next, a third embodiment will be described with reference to Figure 4. Note that components identical to those shown in the previously described embodiments are denoted by the same reference numerals, and redundant descriptions are omitted.

[0033] The superconducting device 1B of the third embodiment comprises a vacuum vessel 2, a shield 3, a power supply 4, a superconducting coil 5, and a diode 6. The shield 3 constitutes the temperature control unit of the third embodiment.

[0034] Diode 6 is located in shield 3. In this way, by placing diode 6 outside the cryogenic region 9, the temperature of diode 6 can be raised higher than that of the cryogenic region 9.

[0035] In the third embodiment, by providing the diode 6 in the shield 3, the temperature of the diode 6 can be increased and the forward voltage Vf can be controlled. This reduces the peak load on the diode 6 and prevents damage to the diode 6.

[0036] (Fourth Embodiment) Next, a fourth embodiment will be described with reference to Figure 5. Note that components identical to those shown in the previously described embodiments are denoted by the same reference numerals, and redundant descriptions are omitted.

[0037] The superconducting device 1C of the fourth embodiment comprises a vacuum vessel 2, a shield 3, a power supply 4, a superconducting coil 5, a diode 6, an insulating section 7, and a heater 8. The shield 3, the insulating section 7, and the heater 8 constitute the temperature control section of the fourth embodiment.

[0038] The diode 6, the insulation section 7, and the heater 8 are located in the shield 3. The insulation section 7 insulates the diode 6 from the shield 3. In this way, the diode 6 can be heated to a higher temperature than the shield 3.

[0039] Furthermore, the heater 8 raises the temperature of the diode 6. In this way, the temperature of the diode 6 provided in the shield 3 can be increased.

[0040] In the fourth embodiment, by providing a diode 6 in the shield 3, and further providing a heat insulating section 7 and a heater 8, the temperature of the diode 6 can be increased and the forward voltage Vf can be controlled. This reduces the peak load on the diode 6 and prevents damage to the diode 6.

[0041] Although the superconducting devices 1 (1A, 1B, 1C) are described based on the first to fourth embodiments, a configuration applied in any one embodiment may be applied to another embodiment, or the configurations applied in each embodiment may be combined.

[0042] According to at least one embodiment described above, by providing a temperature control unit that adjusts the temperature of the diode 6, damage to the diode 6 can be prevented in order to protect the superconducting coil 5 when a quench occurs.

[0043] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, modifications, and combinations are possible without departing from the spirit of the invention. These embodiments or their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0044] 1 (1A, 1B, 1C)...Superconducting device, 2...Vacuum vessel, 3...Shield, 4...Power supply, 5...Superconducting coil, 6...Diode, 7...Insulation section, 8...Heater, 9...Cryogenic region, 11...Power line, 12...High-temperature superconducting lead, 13...Conducting wire, 14...Thermal anchor.

Claims

1. A superconducting coil placed in an extremely low-temperature region to maintain the superconducting state, A diode is connected in parallel with the superconducting coil to the power supply and bypasses the current flowing through the superconducting coil when a quench occurs in the superconducting coil. A temperature control unit for adjusting the temperature of the diode, Equipped with, At least one of the temperature control units is an insulating unit that insulates the diode from the cryogenic region. Superconducting device.

2. The temperature control unit pre-sets the temperature of the diode to be higher than the temperature in the cryogenic region before the quench occurs. The superconducting device according to claim 1.

3. At least one of the temperature control units is a heater that raises the temperature of the diode. The superconducting device according to claim 1 or claim 2.

4. At least one of the temperature control units is a thermal anchor that transmits heat from outside the cryogenic region to the diode. The superconducting device according to claim 1 or claim 2.

5. The diode's conductor is connected to the power line connecting the power supply and the superconducting coil. The material and diameter of the conductor are designed such that the amount of heat input from the diode to the cryogenic region via the conductor is less than or equal to a specific amount. The superconducting device according to claim 1 or claim 2.

6. The aforementioned conductor is made of a high-temperature superconductor. The superconducting device according to claim 5.

7. A superconducting coil provided in an extremely low temperature region for maintaining a superconducting state, A diode is connected in parallel with the superconducting coil to the power supply and bypasses the current flowing through the superconducting coil when a quench occurs in the superconducting coil. A temperature control unit for adjusting the temperature of the diode, Equipped with, At least one of the temperature control units is a shield that reduces thermal radiation from the high-temperature unit, is provided with the diode, and has the cryogenic region inside. Superconducting device.

8. A superconducting coil provided in an extremely low temperature region for maintaining a superconducting state, A diode is connected in parallel with the superconducting coil to the power supply and bypasses the current flowing through the superconducting coil when a quench occurs in the superconducting coil. A temperature control unit for adjusting the temperature of the diode, The shield reduces thermal radiation from the high-temperature part and is provided with the diode and has the cryogenic region inside. At least one of the temperature control units is a heat insulating unit that insulates the diode from the shield. Superconducting device.

9. A superconducting coil provided in an extremely low temperature region for maintaining a superconducting state, A diode is connected in parallel with the superconducting coil to the power supply and bypasses the current flowing through the superconducting coil when a quench occurs in the superconducting coil. A temperature control unit for adjusting the temperature of the diode, The shield reduces thermal radiation from the high-temperature part and is provided with the diode and has the cryogenic region inside. At least one of the temperature control units is a heater that raises the temperature of the diode. Superconducting device.

10. The temperature control unit raises the temperature of the diode to a temperature higher than the temperature in the cryogenic region before the quench occurs. A superconducting device according to any one of claims 7 to 9.

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