JPH08316021A - Cooler - Google Patents

Abstract

PURPOSE: To prevent quenching or excess thermal stress by effectively supplying refrigerant to a superconducting magnet until the magnet is safely stopped even at the time of disabling to circulate the refrigerant owing to the power source failure or the fault of a refrigerant supply unit. CONSTITUTION: A liquid helium reservoir 7 is provided in a heat insulation vessel 15 containing a superconducting magnet 1, an intermediate pressure vessel 16 in which intermediate pressure helium gas is charged is contained in the reservoir 7, a remote operation valve 18a is opened at the time of disabling to circulate refrigerant to supply the helium gas in the vessel 16 to the magnet 1, and hence the magnet can be safely stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forced cooling type superconducting magnet cooling device in which a forced cooling conductor for flowing supercritical helium in a flow passage for cooling is wound.

[0002]

2. Description of the Related Art Forced cooling type superconducting magnets are used in large-scale superconducting devices such as nuclear fusion experimental devices (reactors) and energy storage devices that require high withstand voltage, high magnetic field, and high current density. As shown in FIG. 6, a cooling device for a forced cooling superconducting magnet for a large-scale superconducting device includes a superconducting magnet 1, a supercritical helium circulation pump 4 for circulating supercritical helium in the superconducting magnet 1, and a heat exchanger 5.
And a supercritical helium supply pipe 6a, a supercritical helium return pipe 6b, a remote control valve 18b for connecting them, the supercritical helium circulation pump 4 and a heat exchanger, and a liquid helium 2 therein. A supercritical helium circulation system 6 is configured with the supercritical helium heat exchanger tank 3, and the supercritical helium circulation system 6 is housed in a heat insulating container 15. The helium freezing liquefaction device 1 is provided outside the heat insulating container 15.
0, a liquid helium storage tank 7 for storing the liquid helium 2 purified here, a recovery and purification system 11 for recovering the evaporated helium gas, which is composed of a gas bag, a recovery compressor, a purification device, and the like. A helium gas filling container 12, a helium compressor 13, a valve 14, a recovery pipe 20, and pipes including a low temperature and high pressure helium supply line 21 are provided. The liquid helium 2 in the liquid helium storage tank 7 is transferred to the supercritical helium heat exchanger tank 3 through the liquid helium transfer pipe 9. The superconducting magnet 1 is excited by a power supply source (not shown) via the current lead 8 and the power supply cable 8a.

Since the cooling device thus constructed must be operated stably and reliably for a long period of time, it is necessary to improve the reliability of the major constituent equipment and to make it a double structure. Further, even if the power supply to these main devices is stopped due to a power failure or the like, it is necessary to take measures such as an uninterruptible power supply so that the refrigerant can be circulated through the superconducting magnet.

[0004]

Since the conventional cooling device is configured as described above, the helium refrigeration liquefaction device 10, the supercritical helium circulation pump 4, valves, etc. are prepared for an emergency such as a power failure. It is desirable to provide a plurality of power supply sources of different types for the operation and control of.
However, the helium refrigeration liquefier 10 of these large-scale superconducting devices requires a refrigerating capacity equivalent to several tens of kilowatts to 100 kilowatts at a temperature of 4.5K, and the energy efficiency of the conventional refrigerator ((refrigerating capacity at 4.5K) / If (actual electric power required at room temperature) is set to about 0.003, a huge number of power supply sources are required. Moreover, it is not always used for driving, but it is provided as an emergency. Therefore, generally, the power supply source for the helium refrigeration liquefaction device 10 is one, and a standby power supply such as an uninterruptible power supply is used only for the operation of the remote control valve 18b and the supercritical helium circulation pump 4 which are essential for safe operation. Will be provided.

However, since these basically the same forms (electricity) of energy are used for operation, when not only the main power source but also the standby power source is disturbed, or the power source and the supercritical helium are used. If a power cable between the circulation pumps 4 is broken, or if a refrigerant supply device such as the helium refrigeration liquefaction device 10 or the supercritical helium circulation pump 4 has a device failure, the supercritical condition will occur. Circulation of helium is disabled, and the superconducting magnet 1 can be operated without being quenched (transition to normal conduction), and it can also be stopped. Generally, when the superconducting magnet 1 is stopped, the exciting current is gradually decreased to suppress the release of large accumulated energy.

Therefore, it is necessary to circulate the refrigerant even when the exciting current is falling. Further, when the refrigerant is lost, the temperature of the superconducting magnet 1 will rise rapidly, but the rapid rise in temperature causes a large thermal stress, and the superconducting magnet 1
There is a risk that the insulation and the soundness of the structure will not be maintained, making it impossible to restart.

Therefore, the present invention has been made to solve the above problems, and its purpose is to provide a highly reliable cooling device capable of reliably circulating the refrigerant through the superconducting magnet even when the power supply is lost or the equipment of the refrigerant supply device fails. To provide.

[0008]

In order to solve the above problems, the invention of claim 1 of the present invention provides a cooling device for cooling superconducting magnets by circulating supercritical helium in a supercritical helium circulation system, A liquid helium storage tank is provided in an insulating container containing a superconducting magnet, a medium pressure container for filling helium gas is stored in the liquid helium storage tank, and one end of the medium pressure container is connected via a remote control valve. The supercritical helium circulation system is characterized in that the other end is connected to a superconducting magnet via a remote control valve.

According to a second aspect of the present invention, in a cooling device for cooling superconducting magnets by circulating supercritical helium in a supercritical helium circulation system, a helium gas is filled in an adiabatic container containing the superconducting magnets. A medium pressure vessel is provided, one end of this medium pressure vessel is connected to the supercritical helium circulation system via a remote control valve, and the other end is connected to a superconducting magnet via a remote control valve, and heat is exchanged in the medium pressure vessel. A heat exchanger is provided, and supercritical helium is allowed to flow through the heat exchanger from the supercritical helium circulation system to cool the helium gas in the medium pressure vessel.

According to a third aspect of the present invention, in a cooling device for cooling a superconducting magnet by circulating supercritical helium in a supercritical helium circulation system, the supercritical helium circulation housed in an adiabatic container containing the superconducting magnet. Inside the supercritical helium heat exchanger tank constituting the system, a medium pressure container for filling helium gas is stored, and one end of the medium pressure container is connected to the supercritical helium circulation system via a remote control valve, The end is connected to a superconducting magnet via a remote control valve.

The invention of claim 4 is the invention of claim 1, claim 2,
In the cooling device according to any one of claims 3 to 6, a flow rate adjusting means for adjusting the flow rate of the helium gas is mounted between the medium pressure container and the superconducting magnet.

According to a fifth aspect of the present invention, in a cooling device for cooling superconducting magnets by circulating supercritical helium in a supercritical helium circulation system, a decompressing container that is decompressed in vacuum is provided in a heat insulating container containing the superconducting magnets. , One end of this decompression container is connected to a superconducting magnet via a remote control valve, and the other end is connected to a recovery and purification system with a vacuum exhaust pipe, and it is branched from the middle of the vacuum exhaust pipe and exhausted via a remote control valve. It is characterized by having a device.

According to a sixth aspect of the present invention, in the cooling device according to the fifth aspect, flow rate adjusting means for adjusting the flow rate of the helium gas is mounted between the superconducting magnet and the decompression container. The invention circulates supercritical helium in a supercritical helium circulation system, in a cooling device for cooling a superconducting magnet, in a heat insulating container containing the superconducting magnet, a liquid helium storage tank provided with a heating means for liquid helium, It is characterized in that the upper portion of the liquid helium storage tank and the superconducting magnet are connected via a remote control valve.

The invention according to claim 8 is characterized in that the liquid helium storage tank of the cooling device according to claim 8 is replaced by a supercritical helium heat exchanger tank constituting a supercritical helium circulation system. According to a ninth aspect of the present invention, in the cooling device according to the fourth or sixth aspect, temperature detecting means for detecting at least one of the temperature of the superconducting magnet and the outlet helium gas from the superconducting magnet, and a signal from the temperature detecting means. It is characterized by comprising a controller for controlling the opening area of the flow rate adjusting means.

[0015]

In the cooling device according to the first aspect, the medium pressure container cooled by the liquid helium stored in the liquid helium storage tank is provided when the refrigerant cannot be circulated due to a loss of power, a device failure of the refrigerant supply device, or the like. Stored medium-pressure low temperature helium gas under 10 atm via remote control valve
Since the superconducting magnet can be supplied with a pressure difference, the refrigerant circulation of the superconducting magnet can be secured and the superconducting magnet can be stopped without quenching, and a rapid temperature rise can be suppressed to reduce the thermal stress generated in the superconducting magnet.

In the cooling device corresponding to claim 2,
Medium pressure helium gas of 10 atm or less stored in the medium pressure vessel is cooled by allowing supercritical helium to flow through the heat exchanger provided in the medium pressure vessel during operation and then cooled. When it is not possible, the low temperature helium gas stored in the medium pressure container can be supplied to the superconducting magnet with a pressure difference via the remote control valve.

In the refrigerant device according to claim 3,
When the refrigerant cannot be circulated as described above, a medium-pressure low-temperature helium gas of 10 atm or less stored in a medium-pressure container, which is cooled by liquid helium contained in a supercritical helium heat exchanger tank, is supplied via a remote control valve. , It can be supplied to the superconducting magnet by the pressure difference.

In the refrigerant device according to claim 4,
The supply flow rate (supply time) can be adjusted to an appropriate value by the flow rate adjusting means installed between the medium pressure container and the superconducting magnet. Therefore, when the medium-pressure low-temperature helium gas stored in the medium-pressure container is supplied to the superconducting magnet with a pressure difference, an appropriate flow rate or supply time can be controlled and supplied, so that the reliability is further improved.

In the cooling device corresponding to claim 5,
When the refrigerant cannot be circulated as described above, the superconducting magnet is cooled by sucking the low-temperature helium gas in the supercritical helium circulation line and the low-temperature high-pressure helium supply line through the remote control valve into the decompression container that has been decompressed in advance by the exhaust device. it can.

In the refrigerant device according to claim 6,
Since the suction flow rate (supply time) can be adjusted to an appropriate value by the flow rate adjusting means installed between the superconducting magnet and the decompression container, the reliability is further improved.

In the cooling device according to the seventh or eighth aspect, when the refrigerant cannot be circulated, the low-temperature helium gas supplied to the superconducting magnet is evaporated by the heating means provided in the liquid helium storage tank. Are generated. Further, since the pressure increase generated when vaporizing can be used also as the driving force for circulating the helium gas, the low temperature helium gas can be supplied to the superconducting magnet with a simpler and more compact structure.

In the refrigerant device according to claim 9,
The temperature of at least one of the superconducting magnet and the outlet helium gas from the superconducting magnet is detected by the temperature detecting means, and the flow rate of the helium gas circulating through the superconducting magnet is adjusted by the flow rate adjusting means in response to the temperature change. Therefore, the low temperature helium gas stored in the medium pressure container can be effectively used. Therefore, the reliability is further improved.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system configuration diagram showing a first embodiment of a cooling device of the present invention. This cooling device has a superconducting magnet 1.
A heat exchanger 5 connected to the discharge side of a supercritical helium circulation pump 4 that circulates supercritical helium, and stored in a supercritical helium heat exchanger tank 3 that stores liquid helium 2, a superconducting magnet 1, and the superconducting magnet 1. Critical helium circulation pump 4
And a supercritical helium return pipe 6b for connecting to and via the remote control valve 18b, and a supercritical helium supply pipe 6a for connecting the superconducting magnet 1 and the heat exchanger 5 via the remote control valve 18b. The circulation system 6 is configured.
A collection pipe 20 and a low temperature high pressure helium supply pipe 21 are connected to the supercritical helium circulation system 6. Further, a liquid helium storage tank 7 is provided in the heat insulating container 15, and a medium pressure container 16 for filling the medium pressure helium gas is housed inside the liquid helium storage tank 7.
9, is connected in parallel to the supercritical helium circulation system 6 via the remote control valve 18a and the flow rate adjusting means 22.
The liquid helium 2 in the liquid helium storage tank 7 is transferred from the supercritical helium heat exchanger tank 3 through the transfer pipe 9a.

Further, a temperature detecting means 27 for detecting the temperature of the outlet helium gas flowing through the superconducting magnet 1 or the supercritical helium return pipe 6b, and a controller for controlling the opening area of the flow rate adjusting means 22 by a signal from the temperature detecting means. 28
Is provided.

Next, the function and effect of the first embodiment will be described. In a steady state in which the refrigerant cannot be circulated due to a loss of power source or equipment failure of the refrigerant supply device, the supercritical helium is boosted to a predetermined pressure by the supercritical helium circulation pump 4, and then the supercritical helium heat exchanger tank 3 In the heat exchanger 5 installed inside, the latent heat of vaporization of liquid helium 2 is used to recool it to a predetermined temperature, and it is supplied to the superconducting magnet 1 via the remote control valve 18b and the supercritical helium supply pipe 6a. . The supercritical helium that has cooled the heat generated in the superconducting magnet 1 returns to the supercritical helium circulation pump 4 again via the supercritical helium return pipe 6b and the remote control valve 18b. At the time of initial cooling or steady cooling of the superconducting magnet 1, supercritical helium is filled in the medium pressure container 16 through the cooling pipe 17b and the check valve 19 to a predetermined pressure. The medium pressure container 16 is constantly cooled by the liquid helium 2 in the liquid helium storage tank 7, and can maintain a low temperature and medium pressure state. On the other hand, when the refrigerant cannot be circulated due to the loss of power source or equipment failure, the remote control valve 18b is closed and the remote control valve 1
Open 8a. It should be noted that this operation is almost instantaneously performed in response to the refrigerant circulation inability signal. This remote control valve 1
By closing 8b, the inside of the superconducting magnet 1 has a predetermined pressure,
Although the supercritical helium circulated at the temperature is stopped, it is released to the recovery and purification system 11 through the line of the recovery pipe 20 without putting the pallet. Further, the low temperature medium pressure (around 10 atm) low temperature helium gas stored in the medium pressure container 16 is opened by the remote control valve 18a, and the low temperature helium pipe 17a is opened.
After being obtained, it is supplied to the superconducting magnet 1. Further, since the supply amount can be adjusted by equipping the flow control means 22 such as an orifice or a flow control valve between the superconducting magnet 1 and the medium pressure container 16, the medium pressure stored in the medium pressure container 16 can be adjusted. When the low-temperature helium gas is supplied to the superconducting magnet 1 with a pressure difference, it can be supplied by controlling an appropriate flow rate or supply time. As a control method of the supply amount, the supply amount is calculated in advance from the relationship between the volume and pressure of the intermediate pressure container 16 and the supercritical helium circulation system 6 including the superconducting magnet 1, and the flow rate adjustment such as the orifice and the flow control valve is performed. Means 22
And the temperature detecting means 27 detects the temperature of the superconducting magnet 1 or the outlet helium gas from the superconducting magnet 1, and a signal from the temperature detecting means 22 is used to control the flow rate control valve via the controller 28. There is a method of controlling the opening area of the flow rate adjusting means 22 such as.

As described above, since the flow rate of the helium gas circulating through the superconducting magnet is adjusted by the flow rate adjusting means 22, the low temperature helium gas stored in the medium pressure container 16 can be effectively used. Therefore, the reliability is further improved.

The low-temperature helium gas that has cooled the superconducting magnet 1 is discharged to the recovery / purification system 11 through the supercritical helium return pipe 6b and the recovery pipe 20. By this operation, supercritical helium can be surely supplied while the superconducting magnet 1 is demagnetized.

Therefore, it is possible to stop the superconducting magnet without quenching by ensuring the circulation of the refrigerant in the superconducting magnet, and to suppress the rapid temperature rise and reduce the thermal stress generated in the superconducting magnet.

Next, a second embodiment of the present invention will be described with reference to FIG. The difference from the first embodiment is the method of cooling the medium pressure helium gas in the medium pressure container 16. In this embodiment,
The medium-pressure helium gas in the medium-pressure vessel 16 is cooled by flowing supercritical helium used for cooling the superconducting magnet 1 into the heat exchanger 5 in the medium-pressure vessel 16 during steady operation. Also, the action and effect when the refrigerant circulation is impossible are similar to those of the first embodiment. Further, according to the present embodiment, the liquid helium storage tank 7 is not required, the apparatus configuration can be made compact, and the liquid helium storage tank 7 is also available.
Since the liquid level control of the liquid helium 2 therein and the adjustment of the supply amount are not necessary, the control system of the cooling device is simplified.

A third embodiment will be described with reference to FIG.
In the present embodiment, the medium pressure vessel 16 is housed in the supercritical helium heat exchanger tank 3, and the medium pressure helium gas in the medium pressure vessel 16 is constantly cooled by the liquid helium 2. It has the same effect as the embodiment.

A fourth embodiment will be described with reference to FIG.
The main structure is the same as that of FIG. 1, but a depressurized container 23 decompressed in a vacuum is placed in a heat insulating container 15 that houses the superconducting magnet 1.
The decompression container 23 has one end connected to the superconducting magnet 1 via the remote control valve 18a, and the other end connected to the recovery pipe 20 via the check valve 19 by the vacuum exhaust pipe 24 and the vacuum exhaust pipe. Remote control valve 18 branching from the middle of 24
An exhaust device 25 is provided via b.

Next, the function and effect of this embodiment will be described. The decompression container 23 is constantly evacuated by the exhaust device 25 installed outside the heat insulating container 15 via the remote control valve 18b and the vacuum exhaust pipe 24. On the other hand, when the refrigerant cannot be circulated due to the loss of power supply or equipment failure, the remote control valve 18b provided in front of the exhaust device 25 is closed in conjunction with the remote control valve 18b provided at the same time. Operating valve 18a
Is opened, the superconducting magnet 1 and the supercritical helium in the supercritical helium circulation system 6 are partially recovered by the piping 2
It is released to the recovery purification system 11 via 0. Next, the remote control valve 18c interposed between the superconducting magnet 1 and the decompression container 23 is opened, and the remaining low temperature helium gas is sucked into the decompression container 23 via the cooling pipe 17 connected to the decompression container 23. As a result, the superconducting magnet 1 can be cooled by utilizing the effect of a kind of Joule-Thomson adiabatic expansion, so that the superconducting magnet 1 can be demagnetized without being quenched. Further, when the low pressure helium gas is filled in the decompression container 23 and the internal pressure rises to the vicinity of the atmospheric pressure, the check valve 19 is actuated to release the helium gas to the recovery purification system 11 via the recovery pipe 20, The decompression container 23 is configured so as not to be abnormally filled with helium gas.

A fifth embodiment will be described with reference to FIG.
The main configuration is the same as that of FIGS. 1 to 4, but in this embodiment, the medium pressure container 16 of the first to third embodiments is used.
Instead of installing the decompression container 23 of the fourth embodiment, the heating means 26 is provided in the liquid helium 2 in the supercritical helium heat exchanger tank 3. As the heating means 26,
For example, an electric heater or a heat exchanger that allows gas at room temperature or high temperature to flow therethrough may be used as long as it can vaporize liquid helium.

Next, the function and effect of this embodiment will be described. When the refrigerant cannot be circulated due to power loss or equipment failure, the supercritical helium heat exchanger tank is heated by the heating means 28 provided in the supercritical helium heat exchanger tank 3 for supplying the low temperature helium gas to the superconducting magnet 1. Liquid helium in 3 is vaporized to generate low temperature helium gas.
Since the pressure increase in the supercritical helium heat exchanger tank 3 that occurs when vaporizing can also be used, low-temperature helium gas can be supplied to the superconducting magnet with a simpler and more compact structure.

Instead of providing the heating means 28 in the supercritical helium heat exchanger tank 3, another liquid helium storage tank 7 may be provided in the heat insulating container 15 and the heating means 28 may be provided therein.

Furthermore, the present invention is not limited to the above-described embodiments, and by using the embodiments in combination, the supply amount of low-temperature helium gas can be increased, and the heat load of the superconducting magnet 1 is large. This is effective when it is desired to extend the supply time of low temperature helium gas.

Further, from the flow rate adjusting means 22 described in the first embodiment, the temperature detecting means 27 for detecting the temperature of at least one of the superconducting magnet 1 and the outlet helium gas from the superconducting magnet, and the temperature detecting means 27. The configuration in which the controller 28 for controlling the opening area of the flow rate adjusting means 22 by the signal of (1) is provided to control the supply amount of the low temperature helium gas to the superconducting magnet 1 can be applied to other embodiments.

[0038]

As described above, according to the present invention, the refrigerant can be surely supplied to the superconducting magnet even when the power is lost or the equipment of the refrigerant supply device is broken, and quenching and generation of excessive thermal stress are avoided. It is possible to provide a highly reliable refrigerant device capable of safely stopping the superconducting magnet.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing a first embodiment of a cooling device of the present invention.

FIG. 2 is a system configuration diagram showing a second embodiment of the cooling device of the present invention.

FIG. 3 is a system configuration diagram showing a third embodiment of the cooling device of the present invention.

FIG. 4 is a system configuration diagram showing a fourth embodiment of the cooling device of the present invention.

FIG. 5 is a system configuration diagram showing a fifth embodiment of the cooling device of the present invention.

FIG. 6 is a system configuration diagram showing an example of a conventional cooling device.

[Explanation of symbols]

 1 ... Superconducting magnet 2 ... Liquid helium 3 ... Supercritical helium heat exchanger tank 4 ... Supercritical helium circulation pump 5 ... Heat exchanger 6 ... Supercritical helium circulation system 6a ... Supercritical helium supply pipe 6b ... Supercritical helium return pipe 7 ... Liquid helium storage tank 8 ... Current lead 9 ... Liquid helium transfer pipe 10 ... Helium refrigeration liquefier 11 ... Recovery and purification system 14 ... Valve 15 ... Insulation container 16 ... Medium pressure container 17a, 17b, 17c ... Low temperature helium pipe 18a, 18b , 18c ... Remote control valve 19 ... Check valve 20 ... Recovery pipe 21 ... Low temperature / high pressure helium pipe 22 ... Flow rate adjusting means 23 ... Decompression container 24 ... Vacuum exhaust pipe 25 ... Exhaust device 26 ... Heating means 27 ... Temperature detecting means 28 ... Controller

Claims (9)

[Claims] 1. A cooling device for cooling a superconducting magnet by circulating supercritical helium in a supercritical helium circulation system, wherein a liquid helium storage tank is provided in an adiabatic container containing the superconducting magnet, and the liquid helium storage tank is provided inside the liquid helium storage tank. ,
A medium pressure container for filling helium gas was housed, one end of the medium pressure container was connected to the supercritical helium circulation system via a remote control valve, and the other end was connected to a superconducting magnet via a remote control valve. Characteristic cooling device. 2. A cooling device for cooling a superconducting magnet by circulating supercritical helium in a supercritical helium circulation system, wherein a heat insulating container containing the superconducting magnet is provided with a medium pressure container for filling helium gas. , One end of this medium pressure vessel is connected to the supercritical helium circulation system via a remote control valve, and the other end is connected to a superconducting magnet via a remote control valve, and a heat exchanger is arranged in the medium pressure vessel. A cooling device, characterized in that supercritical helium is caused to flow through the heat exchanger from a supercritical helium circulation system to cool the helium gas in the medium pressure vessel. 3. A cooling device for cooling a superconducting magnet by circulating supercritical helium in the supercritical helium circulation system, which constitutes a supercritical helium circulation system housed in an adiabatic container containing the superconducting magnet. Inside the helium heat exchanger tank, a medium pressure container for filling helium gas is housed, one end of the medium pressure container is connected to the supercritical helium circulation system via a remote control valve, and the other end is connected to a remote control valve. A cooling device connected to a superconducting magnet via 4. The cooling according to claim 1, wherein a flow rate adjusting means for adjusting the flow rate of helium gas is mounted between the medium pressure container and the superconducting magnet. apparatus. 5. A cooling device for cooling a superconducting magnet by circulating supercritical helium in a supercritical helium circulation system, wherein a vacuum-decompressed decompression container is provided in an adiabatic container containing the superconducting magnet. One end was connected to the superconducting magnet via the remote control valve, the other end was connected to the recovery system with the vacuum exhaust pipe, and the exhaust device was provided by branching from the middle of the vacuum exhaust pipe via the remote control valve. Characteristic cooling device. 6. The cooling device according to claim 5, further comprising a flow rate adjusting means for adjusting the flow rate of the helium gas, which is provided between the superconducting magnet and the decompression container. 7. A cooling device for cooling a superconducting magnet by circulating supercritical helium in a supercritical helium circulation system, wherein a liquid helium storage tank equipped with a heating means for liquid helium is provided in an adiabatic container containing the superconducting magnet. A cooling device, characterized in that an upper part of the liquid helium storage tank is connected to a superconducting magnet via a remote control valve. 8. The cooling device according to claim 7, wherein the liquid helium storage tank is replaced by a supercritical helium heat exchanger tank constituting a supercritical helium circulation system. 9. A temperature detecting means for detecting the temperature of at least one of a superconducting magnet and an outlet helium gas from the superconducting magnet, and a controller for controlling an opening area of a flow rate control valve by a signal from the temperature detecting means. The cooling device according to claim 4, wherein the cooling device is a cooling device.