JP2016211803A - Cryogenic container and superconductive magnet device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cryogenic container and a superconductive magnet device in which a thermal link between a refrigerator cold head cooling part and a part of coolant member is connected at the time of driving the refrigerator to keep a low heat resistance and is separated at the time of stopping the refrigerator to keep a high heat resistance, and a degree of freedom in thermal design is improved.SOLUTION: A cryogenic container 10 cools coolant 12 to be cooled to a cryogenic temperature by a cryogenic refrigerator 14. A refrigerator cold head 15 installed at a heat insulation vacuum container 11 within this cryogenic container has a cold head cooling part 25 extended therein, the refrigerator cold head is constituted in such a way that the cold head cooling part is pressed and contacted with a part of the coolant to be cooled to form a contact part due to a pressure difference between atmospheric pressure outside the heat insulation vacuum container and vacuum in the heat insulated vacuum container. In the refrigerator cold head, the cold head cooling part is separated from a part of the coolant to be cooled at the time of stopped operation of the cryogenic refrigerator and the coolant to be cooled is held at an independent non-contacted state.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a cryogenic container and a superconducting magnet apparatus using a cryogenic refrigerator.

  In recent years, as a means for cooling a superconducting magnet, a cooling apparatus using a cryogenic refrigerator without using a cryogenic refrigerant has been mainstream instead of a cooling apparatus using a cryogenic refrigerant. Cryogenic containers using conventional cryogenic refrigerators, especially superconducting magnet devices that cool superconducting coils as the object to be cooled, cool the superconducting magnets only by operating the cryogenic refrigerator, compared to cooling with cryogenic refrigerants. Because it can be performed, it is being applied to medical, industrial and research applications.

  The cooling device using a cryogenic refrigerator eliminates the need for cryogenic liquid refrigerant and can minimize the heat capacity of the cooling body. The temperature will rise instantly. Among them, the metal superconducting magnet is cooled to a temperature of 4K level, and the specific heat of the metal member is small, so the temperature rise rate is large.

  When the cryogenic refrigerator of the cooling system is abnormal, the time to reach the critical temperature of the superconductor, which is the object to be cooled, is short even with a slight amount of heat entering the cryogenic vessel, and the superconducting coil maintains the superconducting state (Meissner effect). When the temperature becomes higher than the critical temperature at which quenching occurs, quenching occurs, and the superconducting coil cannot maintain the superconducting state.

  Particularly, in the cryogenic refrigerator, when the operation is stopped, the refrigerator constituent member becomes a heat penetration facilitating member that causes heat penetration into the cryogenic container due to heat conduction.

  On the other hand, it is necessary to stop the operation of the cryogenic refrigerator at the time of maintenance of the refrigerator even when the cryogenic refrigerator is not in an abnormal state. Since the cryogenic refrigerator is thermally coupled to the superconducting coil, which is usually the object to be cooled, by a heat transfer member with high thermal conductivity, the temperature of the cryogenic refrigerator is increased to the room temperature after the operation of the cryogenic refrigerator is stopped. Takes several days.

  Moreover, the cryogenic refrigerator has a small refrigerating capacity compared to the cooling by the cryogenic refrigerator, and the initial cooling time from room temperature to a predetermined cooling temperature becomes long. In order to shorten the initial cooling time, there is a method to increase the refrigeration capacity by using a plurality of refrigerators, but after cooling to a predetermined cooling temperature using a plurality of refrigerators, Power consumption will be excessive for the number of units, resulting in poor operating efficiency.

JP 2004-55643 A JP 2002-208511 A JP 2013-130336 A

  As a means of cooling the superconducting magnet, the superconducting magnet of the conduction cooling type can cool the superconducting magnet that is the object to be cooled only by operating the cryogenic refrigerator. There is an advantage that the liquid refrigerant is not necessary, and there is no need to worry about evaporation (consumption) of the cryogenic refrigerant or refilling, and the operation is simplified.

  On the other hand, because the thermal coupling between the cryogenic refrigerator and the superconducting magnet is thermally linked by a heat transfer member with high thermal conductivity, the temperature rise of the refrigerator during maintenance and initial cooling There are problems such as a long period. These problems are solved by providing a thermal switch that can disconnect or connect the thermal link between the cryogenic refrigerator and the superconducting magnet.

  The thermal switch is required to rapidly start a cryogenic refrigerator with a low thermal resistance when the thermal switch is ON, and to reduce the heat intrusion source with a high thermal resistance when the switch is OFF. Cryogenic containers and superconducting magnet devices that require 4K level cryogenic cooling have a strong demand for thermal switches with good characteristics because of their low refrigeration capacity and heat penetration, and strict thermal design.

  The embodiment of the present invention has been made in consideration of the above-described circumstances, and maintains a low thermal resistance by connecting a thermal link between the refrigerator cold head cooling unit and a part of the object to be cooled when the refrigerator is driven. Another object of the present invention is to provide a cryogenic container and a superconducting magnet device that are separated when the refrigerator is stopped to maintain high thermal resistance and to improve the degree of freedom in thermal design.

  In order to solve the above-described problem, the cryogenic container according to the present embodiment includes a heat-insulated vacuum container that houses a body to be cooled, and a refrigerator cold head installed in the heat-insulated vacuum container. The refrigerator cold head has a cold head cooling section extending in the heat insulation vacuum vessel, and the refrigerator cold head is formed by a differential pressure between the atmospheric pressure outside the heat insulation vacuum vessel and the vacuum in the heat insulation vacuum vessel. The cold head cooling unit is pressed and contacted with a part of the object to be cooled at a predetermined surface pressure to form a contact unit, and the refrigerator cold head is configured such that the cold head cooling unit is The present invention provides a cryogenic container that is separated from a part of a body to be cooled and holds the body to be cooled in an independent non-contact state.

  Further, the cryogenic container according to the present embodiment is provided with a refrigerator and a main refrigerator in an adiabatic vacuum container, and a cooled object is stored in a radiation shield container provided in the adiabatic vacuum container, The main refrigerator is installed on the heat transfer plate so as to constantly cool the object to be cooled, and the refrigerator has a cold head cooling part in which the refrigerator cold head extends into the heat insulating vacuum vessel as a part of the object to be cooled. A contact portion that is detachably contacted is configured, and the contact portion of the refrigerator cold head is configured such that the cold head cooling portion is caused by a differential pressure between an atmospheric pressure outside the heat insulating vacuum vessel and a vacuum inside the heat insulating vacuum vessel. A part of the object to be cooled is pressed into contact with a predetermined surface pressure, and the cold head of the refrigerator cold head is separated from a part of the object of cooling when the refrigerator is stopped. Non-contact part of body There is provided a cryogenic vessel, characterized in that to hold the state.

  Furthermore, in the superconducting magnet device according to the present embodiment, the superconducting magnet according to claim 11 or 12, wherein a superconducting coil is housed in a radiation shield container in a heat insulating vacuum container as the object to be cooled. A magnet device is provided.

  In the present invention, the thermal link between the refrigerator cold head cooling unit and a part of the object to be cooled is connected at the time of driving the refrigerator to maintain a low thermal resistance, and disconnected when the refrigerator is stopped to maintain a high thermal resistance. It is possible to provide a cryogenic container and a superconducting magnet device with improved design freedom.

The figure which shows the structure of 1st Embodiment of the cryogenic container or superconducting magnet apparatus at the time of thermal switch ON. The figure which shows the structure of 1st Embodiment of the cryogenic container or superconducting magnet apparatus at the time of thermal switch OFF. The figure which shows the structure of 2nd Embodiment of the cryogenic container or superconducting magnet apparatus at the time of thermal switch ON. The figure which shows the structure of 2nd Embodiment of the cryogenic container or superconducting magnet apparatus at the time of thermal switch OFF. The figure which shows the structure of 3rd Embodiment of the cryogenic container or superconducting magnet apparatus at the time of thermal switch ON. The figure which shows the structure of 3rd Embodiment of the cryogenic container or superconducting magnet apparatus at the time of thermal switch OFF. The figure which shows the structure of 4th Embodiment of the cryogenic container or superconducting magnet apparatus at the time of thermal switch ON. The figure which shows the structure of 4th Embodiment of the cryogenic container or superconducting magnet apparatus at the time of thermal switch OFF.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  The present embodiment relates to a cryogenic container or a superconducting magnet device that cools an object to be cooled to a cryogenic temperature using a cryogenic refrigerator. A cryogenic container that cools an object to be cooled with a cryogenic refrigerator can realize a cryogenic environment without using a cryogenic liquid refrigerant such as liquid helium. It is widely applied to industrial, medical, and research applications such as magnetic levitation trains and MRI devices because it is easy to realize a cryogenic environment by only operating a cryogenic refrigerator.

[First Embodiment]
1 and 2 are schematic configuration diagrams showing a first embodiment of a cryogenic container or a superconducting magnet device. The cryogenic container 10 has a box-shaped heat insulating vacuum container 11 as a cryostat. The adiabatic vacuum vessel 11 can be kept in a vacuum state and is evacuated by a vacuum pump (not shown). A body 12 to be cooled that is operated in a cryogenic cooling environment is stored in the heat insulating vacuum vessel 11. The object to be cooled 12 includes, for example, a superconducting coil, a superconducting element, a SQUID (Superducting Quantum Interference Device) application device, and a device using a cryogenic environment.

  The heat insulating vacuum vessel 11 is provided with a refrigerator cold head 15 constituting a cryogenic refrigerator 14. The refrigerator cold head 15 constitutes a cryogenic refrigerator 14 together with its driving means and a compressor outside the heat insulating vacuum vessel 11, and the cryogenic refrigerator 14 is generally used for a refrigerator cooled superconducting magnet. It is a GM (Gifford-McMahon) type refrigerator. The refrigerator cold head 15 is provided on an installation base 18 that can be raised and lowered via a bellows 17 on a container lid 16 of the heat insulating vacuum container 11. The bellows 17 constitutes a partition wall (vacuum container partition wall) that keeps the inside of the heat insulating vacuum container 11 in a vacuum state, and partitions the heat insulating vacuum container 11 into atmospheric pressure outside the container and vacuum inside the container.

  The refrigerator cold head 15 is connected to a drive current source 21 via a drive cable 20, and the refrigerator cold head 15 is driven by the drive current from the drive current source 21. The drive cable 20 is provided with a power supply detection relay 22, and the power supply detection relay 22 detects whether or not the cryogenic refrigerator 14 is driven. The power supply detection relay 22 controls the motor operation of the cold head vertical control motor 23 provided on the heat insulating vacuum vessel 11.

  On the other hand, the refrigerator cold head 15 installed on the adiabatic vacuum vessel 11 is terminated by a cold head cooling unit 25 constituting a cooling stage extending into the adiabatic vacuum vessel 11. The cold head cooling unit 25 is provided so as to be in thermal contact with the heat transfer plate 27 by a thermal switch 26, and constitutes thermal coupling by a thermal link. The contact portion of the thermal switch 26 constitutes a mechanical or contact thermal switch for bringing the cold head cooling unit 25 into thermal contact with the heat transfer plate 27. The heat transfer plate 27 is made of a metal material having a high thermal conductivity, such as copper or aluminum. The heat transfer plate 27 is formed integrally with the body to be cooled 12 and constitutes a part of the body to be cooled 12. The cryogenic refrigerator 14 cools the cooled object 12 to an extremely low temperature, for example, 4K, from the cold head cooling unit 25 of the refrigerator cold head 15 via the heat switch 26 and the heat transfer plate 27, thereby insulating the cooled object 12. The vacuum vessel 11 is kept at a very low temperature in a vacuum state.

  By the way, the driving state of the cryogenic refrigerator 14 is detected by the power supply detection relay 22, and during driving, the refrigerator cold head 15 is lowered by the cold head vertical control motor 23, and the cold head cooling unit 25 is thermally connected to the heat transfer plate 27. A link is configured to be in thermal contact and thermally coupled. At this time, the thermal switch 26 is kept in the ON state (FIG. 1). Due to the differential pressure between the atmospheric pressure acting outside the container and the vacuum inside the container, the heat insulating vacuum container 11 acts on the refrigerator cold head 15 in the downward direction of FIG. Is pressed downward. Thereby, a surface pressure is applied to the contact portion of the thermal switch 26, and the contact area is increased to reduce the thermal resistance.

  On the other hand, the bellows 17 that expands and contracts while keeping the inside of the heat insulating vacuum vessel 11 airtight has a spring-like elastic function and applies an upward force against the atmospheric pressure to the refrigerator cold head 15, so that the contact portion of the thermal switch 26 It is possible to control the surface pressure acting on the surface.

  FIG. 2 shows a configuration of the cryogenic container 10 or the superconducting magnet device when the thermal switch 26 is OFF. When the cryogenic refrigerator 14 is stopped due to a power failure or the like and is in a non-driven state, the feed detection relay 22 detects that the cryogenic refrigerator 14 is not driven, and the cold head vertical control motor 23 performs the refrigerator. The cold head 15 is pushed up to disconnect the contact part of the thermal switch 26, and the cold head cooling part 25 is kept out of contact with the heat transfer plate 27.

  Specifically, when the cryogenic refrigerator 14 is stopped due to a power failure or the like, the power feeding detection relay 22 detects that the cryogenic refrigerator 14 is not driven, and drives the cold head vertical control motor 23 to drive the cam. The mechanism 28 is cam operated. Due to the cam operation of the cam mechanism 28, the installation base 18 is guided and raised by the guide post 29, and the refrigerator cold head 15 has a downward pressure difference between the gravity and the atmospheric pressure outside the insulated vacuum vessel 11 and the vacuum inside the vessel. Pushed up against. When the cryogenic refrigerator 14 is stopped, the cold head up / down control motor 23 and the cam mechanism 28 constitute an ascending mechanism of the refrigerator cold head 15. When the refrigerator cold head 15 is pushed up, the cold switch 25 is disconnected from the heat transfer plate 27 and the heat switch 26 is brought into a non-contact state. The cold head cooling unit 25 is separated from the heat transfer plate 27 and is in a non-contact state, and the thermal switch 26 is turned off. In place of the cam mechanism 28 operated by driving the cold head vertical control motor 23, the installation table 18 is driven up and down using a lifting device such as a fluid cylinder device or an air cylinder device, and the thermal switch 26 is turned on / off. You may make it operate.

[Operation of First Embodiment]
When the cryogenic refrigerator 14 stops, the power supply detection relay 22 detects the stop of the refrigerator, drives the cold head vertical control motor 23 to operate the cam mechanism 28 and the like, and lifts the refrigerator cold head 15. . The refrigerator cold head 15 moves upward, the cold head cooling unit 25 is separated from the heat transfer plate 27 and rises, and the heat switch 26 is turned off to be in a non-contact state. The heat switch 26 is turned OFF, the heat link from the refrigerator cold head 15 to the cooled object 12 is eliminated, and the heat coupling is interrupted, so that heat intrusion can be suppressed. When the heat switch 26 is turned off and the cold head cooling unit 25 is disconnected from the heat transfer plate 27 and brought into a non-contact state, the thermal coupling from the refrigerator cold head 15 to the cooled object 12 is canceled. The cooled object 12 is held in an independent non-contact state in the heat insulating vacuum vessel 11, and the temperature rise rate of the cooled object 12 can be reduced.

  When the object to be cooled 12 is a superconducting coil wound around a winding frame (not shown), the cryogenic container 10 constitutes a superconducting magnet device. In the superconducting magnet device 10, the heat switch 26 is turned off, the cold head cooling unit 25 is disconnected from the heat transfer plate 27, and the refrigerator cold head 15 is in a non-contact state where the superconducting coil 12 is cut off by thermal coupling. For this reason, although the superconducting coil 12 constituting the superconducting magnet is made of a metal member having a small specific heat and has a small heat capacity, the cold head cooling unit 25 is disconnected from the heat transfer plate 27 and is independent in a non-contact state. Therefore, heat penetration into the superconducting coil 12 can be suppressed. Therefore, it is possible to prevent the temperature of the superconducting coil 12 from rapidly rising to the critical temperature, to prevent the superconducting coil 12 from quenching, and to delay the time until quenching.

[Modification of First Embodiment]
In the cryogenic container 10 or the superconducting magnet apparatus of the first embodiment, the driving state of the cryogenic refrigerator 14 is always detected by the power supply detection relay 22, and the cold head vertical control motor 23 is automatically detected by the power supply detection relay 22. Although an example in which the drive control is performed and the thermal switch 26 is automatically turned on / off has been shown, the thermal switch 26 may be turned on / off manually. Even if the thermal switch 26 is turned ON / OFF by manual operation, the surface pressure is applied to the contact portion of the thermal switch 26 using the differential pressure between the atmospheric pressure outside the heat insulating vacuum vessel 11 and the vacuum inside the vessel. The surface pressure causes the cold head cooling unit 25 to be pressed into contact with a part (heat transfer plate 27) of the body 12 to be cooled, thereby reducing the specific heat resistance and effectively reducing the thermal resistance of the thermal switch contact unit. Can be aimed at.

  1 and 2, the refrigerator cold head 15 has an example including a single-stage cold head cooling unit (cooling stage) 25. However, the refrigerator cold head includes a plurality of stages of cold head cooling units, for example, A cryogenic refrigerator including a two-stage cold head cooling unit (cooling stage) may be used.

  Furthermore, in the first embodiment, an example in which the cryogenic vessel 10 is provided with the bellows 17 to form the vacuum vessel partition wall is shown. However, the refrigerator cold head 15 is replaced with a shaft seal such as an O-ring or the operation instead of the bellows 17. It is good also as a structure which makes the heat insulation vacuum vessel 11 shaft-seal and support the refrigerator cold head 15 by the structure which provided the possible airtight mechanism.

  In addition, the thermal switch 26 brings the cold head cooling unit 25 of the refrigerator cold head 15 into thermal contact (thermal coupling) with a part (heat transfer plate 27) of the object to be cooled 12 so as to switch between the contact state and the non-contact state. In the example, the cold head cooling unit 25 (or the heat transfer plate 27) is supported so as to be movable (movable up and down). And if the contact part of the heat switch 26 is the contact surfaces which gave the plane processing mutually, surface shape restrictions will not be received fundamentally. The contact part of the thermal switch 26 can suppress an increase in contact thermal resistance per unit area in a vacuum caused by a gap due to a difference in flatness by bringing the contact surfaces into pressure contact with each other.

  Furthermore, if the contact surfaces of the contact portion of the thermal switch 26 are subjected to processing for improving surface roughness and flatness such as polishing and mirror processing, for example, mirror finish processing, the contact thermal resistance can be reduced. it can. In addition, a smooth polished surface with reduced surface roughness on one side of the contact surface, and a surface with intentionally increased surface roughness on the other side, when the surfaces are brought into contact with each other, The number of contact points increases, and the contact thermal resistance can be reduced.

  In addition, the heat switch 26 locally heats the contact surface in order to reduce the occurrence of work hardening on the surfaces of the contact surfaces due to multiple ON / OFF operations and an increase in contact thermal resistance, By performing an annealing process for recovery and recrystallization to soften, a contact thermal resistance recovery device can be configured, and the thermal switch 26 with good reproducibility can be obtained.

[Effect of the first embodiment]
In this embodiment, the thermal link between the cold head cooling part of the refrigerator cold head and a part of the cooled object is connected and thermally coupled at the start of the refrigerator to maintain a low thermal resistance, and the refrigerator is stopped. Sometimes the thermal link is disconnected by breaking the thermal link, maintaining a high thermal resistance in a non-contact state, and keeping the object to be cooled in a separate non-contact state in which the thermal coupling is interrupted in a vacuum in an insulated vacuum vessel. The degree of freedom of design can be improved.

  In addition, when the heat switch is turned on, the thermal resistance between the cold head cooling part of the refrigerator cold head and a part of the object to be cooled (heat transfer plate) can be reduced so that the refrigerator cold head can be started up rapidly. When the heat switch is OFF, the cold head cooling part and a part (heat transfer plate) of the object to be cooled can be separated from each other and brought into a non-contact state to increase the thermal resistance and reduce the amount of heat entering the object to be cooled. .

[Second Embodiment]
Next, a second embodiment of the cryogenic container and the superconducting magnet device will be described with reference to FIGS. 3 and 4.

  In describing the cryogenic container or the superconducting magnet apparatus according to the second embodiment, the same components as those of the cryogenic container 10 or the thermoconducting magnet apparatus shown in the first embodiment are denoted by the same reference numerals and overlapped. The explanation is omitted or simplified.

  In the cryogenic container 10A or superconducting magnet apparatus of the second embodiment, a spring / displacement mechanism 30 is provided on the object to be cooled 12 side of the thermal switch 26. The spring / displacement mechanism 30 is provided on a heat transfer plate 27 having excellent heat conductivity, and a coil spring guided by a guide post is interposed between the heat transfer plate 27 and the cold head cooling portion 25 of the refrigerator cold head 15. Is in thermal contact. The superconducting magnet device has a superconducting coil installed as an object to be cooled that is housed in the cryogenic vessel 10.

  If the effect of heat transfer is not sufficient for the spring / displacement mechanism 30 and cannot be expected, the heat transfer plate 33 forms part of the body 12 to be cooled as shown in FIGS. Provided on the plate 27. The flexible heat transfer plate 33 is pressed against the cold head cooling part 25 side of the refrigerator cold head 15 by the spring force of the spring / displacement mechanism 30 to constitute a contact part of the heat switch 26. The thermal switch 26 forms a thermal link between the heat transfer plate 27 and the cold head cooling unit 25, thereby strengthening thermal bonding. The flexible heat transfer plate 33 is made of a metal material having good thermal conductivity, for example, copper or aluminum material.

[Operation of Second Embodiment]
When the cryogenic refrigerator 14 is driven, the power supply detection relay 22 detects the driving state, and the cold head up / down control motor 23 lowers the refrigerator cold head 15, and the contact portion of the thermal switch 26 forms a thermal link. The thermal contact is good and the thermal switch 26 is kept in the ON state (FIG. 3).

  When the contact pressure is applied to the contact portion of the heat switch 26 while the heat switch 26 is in the ON state, the pressing force of the spring / displacement mechanism 30 acts on the flexible heat transfer plate 33 of the heat transfer member. The surface direction of the heat plate 33 is corrected and adjusted so that almost the entire surface comes into contact with the cold head cooling part 25 of the refrigerator cold head 15 in an equal pressure manner.

  As a result, the contact portion of the thermal switch 26 has good thermal contact between the cooling stage, which is the cold head cooling unit 25, and the flexible heat transfer plate 33, and the contact thermal resistance can be reduced. It is cooled to a very low temperature, for example 4K, and kept at a very low temperature.

  Further, when the cryogenic refrigerator 14 is stopped, it is detected that the cryogenic refrigerator 14 is not driven due to a power failure or the like by the power feeding detection relay 22 and the cold head vertical control motor 23 detects that the cryogenic refrigerator 14 is stopped. The cam mechanism 28 and the like are operated to push up the refrigerator cold head 15. As the refrigerator cold head 15 rises, the cold head cooling unit 25 is pushed up, and the cold head cooling unit 25 is disconnected from the flexible heat transfer plate 33 and does not contact the flexible heat transfer plate 33 as shown in FIG. It becomes a contact state.

  When the cryogenic refrigerator 14 is stopped, as shown in FIG. 4, the thermal switch 26 is turned OFF, the contact portion of the thermal switch 26 is disconnected, and the thermal link is eliminated. When the heat switch 26 is turned off, the cold head cooling unit 25 and the flexible heat transfer plate 33 constituting the cooling stage are brought into a non-contact state, and the heat intrusion from the refrigerator cold head 15 to the cooled object 12 is suppressed. it can.

  In the cryogenic container 10 or the cryogenic magnet device of the second embodiment, the example in which the spring / displacement mechanism 30 is provided on the cooled object 12 side has been described, but the spring / displacement mechanism 30 is a cold head of the refrigerator cold head 15. You may provide in the cooling unit 25 side. Specifically, the flexible heat transfer plate 33 has a spring / displacement mechanism 30 attached to the cold head cooling unit 25, and the flexible heat transfer plate 33 and the heat transfer plate 27 constituting a part of the cooled object 12. A thermal switch 26 constituting a thermal link may be provided between the two. Also in this case, the thermal switch 26 is provided between the cold head cooling unit 25 and a part of the cooled object 12.

[Effects of Second Embodiment]
In the cryogenic container 10A or the superconducting magnet apparatus of the second embodiment, in addition to the effects of the first embodiment, when the trouble such as the failure of the contact portion of the thermal switch 26 is taken out, only the cryogenic refrigerator 14 is taken out for maintenance and repair. This makes it possible to improve the maintainability.

[Third Embodiment]
A third embodiment of the cryogenic container and the superconducting magnet apparatus will be described with reference to FIGS. 5 and 6.

  In describing the cryogenic container or the superconducting magnet apparatus according to the third embodiment, the same components as those of the cryogenic container 10 or the superconducting magnet apparatus shown in the first embodiment are denoted by the same reference numerals and redundant descriptions are given. Omit or simplify. The cryogenic container 10B is provided with a cryogenic element, a SQUID application device, or the like as the cooled object 12, and the cooled object 12 provided with a thermoconductive coil constitutes a superconducting magnet device.

  The cryogenic vessel 10B or superconducting magnet device of the third embodiment is basically different in the configuration of the contact portion of the thermal switch 26, and other configurations are substantially different from the cryogenic vessel 10 or superconducting magnet device of the first embodiment. Not different. In the cryogenic container 10B or the superconducting magnet apparatus shown in FIGS. 5 and 6, the contact portion of the thermal switch 26 has one contact surface, and the contact surface of the cold head cooling portion 25 of the refrigerator cold head 15 is one. On the other hand, a plurality of contact surfaces on the cooled object 12 side are provided. A heat transfer plate 27 is provided with a plurality of spring / displacement mechanisms 35 on the contact surface on the cooled object 12 side.

  The spring / displacement mechanism 35 is interposed between the cold head cooling unit 25 and the heat transfer plate 27, and a plurality of coil springs are in elastic contact with each contact surface of the thermal switch 26. Each coil spring is guided by a guide post so as to expand and contract. In the case where the effect of heat transfer cannot be sufficiently expected by the spring / displacement mechanism 35, the flexible heat transfer plate 36 is interposed between the cold head cooling unit 25 and the spring / displacement mechanism 35 of the heat transfer plate 27. Provided. The flexible heat transfer plate 36 is connected to the heat transfer plate 27 in a cantilever shape, and the contact surface on the cooled object 12 side is divided into a plurality of connected states. The plurality of contact surfaces of the flexible heat transfer plate 36 are pressed against and brought into thermal contact with the contact surface of the cold head cooling unit 25 to the spring / displacement mechanism 35, and heat from the refrigerator cold head 15 to the cooled object 12 side. It has good conduction and forms a thermal link by thermal contact.

  The cryogenic container 10B or superconducting magnet device of the third embodiment has one contact surface on the contact part of the thermal switch 26, one contact surface on the refrigerator cold head 15 side, whereas the other contact surface, The to-be-cooled body 12 side contact surface is comprised in multiple. Each of the plurality of contact surfaces on the cooled object 12 side is independently pressed and contacted to the cold head cooling unit 25 side by a spring / displacement mechanism 35 having a variable surface direction. Thus, the thermal switch 26 forms a thermal link by thermal contact.

[Operation of Third Embodiment]
In the third embodiment, in the contact portion of the thermal switch 26, there is one contact surface, that is, one contact surface on the refrigerator cold head 15 side in FIG. 5, whereas the other contact surface is on the cooled object 12 side. A plurality of contact surfaces are provided, and each has a spring / displacement mechanism 35 that can change the surface direction. With this configuration, the contact portions of the thermal switch 26 are formed integrally as a whole because the contact surfaces are small even if the contact surfaces are processed surfaces with relatively low flatness. The spatial gap of the contact portion due to the difference in flatness can be made smaller than the contact surface. If the number of divisions of the contact portion of the thermal switch 26 is N on the same processed surface, the gap between the divided contact surfaces can be reduced by about 1 / N of the gap between the contact surfaces in the integrated configuration. Be expected.

  When the cryogenic refrigerator 14 is driven, the refrigerator cold head 15 is in the driving state shown in FIG. 5, and the cold head cooling unit 25 is a flexible heat transfer plate which is a heat transfer member by the elastic action of each spring / displacement mechanism 35. 36 and a contact state. The thermal switch 26 is turned on with a thermal link formed by thermal contact. When the heat switch 26 is in the ON state, the cold head cooling unit 25 of the refrigerator cold head 15 has a good thermal contact with a part of the cooled object 12, the flexible heat transfer plate 36, and the cooled object 12 is cooled, It is kept in a cryogenic state.

  At that time, unlike the case where the entire contact surface is integrated, the contact portion of the thermal switch 26 is formed with a plurality of contact surfaces on the cooled object 12 side by the flexible heat transfer plate 36, and the plurality of contact surfaces are the cold head cooling portion. The contact surface of the (cooling stage) and the spring / displacement mechanism are individually elastically pressed and contacted. Since the area of each contact surface on the cooled object 12 side is small and each contact surface is pressed and contacted to the cold head cooling unit 25 side by the spring / displacement mechanism 35, the spatial gap of the contact part of the thermal switch 26 is contacted. The surfaces can be made smaller than those formed integrally as a whole, and the thermal resistance can be reduced.

  The contact portion of the thermal switch 26 can reduce the contact thermal resistance per unit area, and can minimize the total surface area of the contact portion.

  When the cryogenic refrigerator 14 is stopped, it is detected that the cryogenic refrigerator 14 is not driven by the power supply detection relay 22 and the cam mechanism 28 is operated by the cold head vertical control motor 23 when the cryogenic refrigerator 14 is stopped. The refrigerator cold head 15 is pushed up through the like. As the refrigerator cold head 15 rises, the cold head cooling unit 25 is pushed up integrally, and the cold head cooling unit 25, which is a cooling stage, is separated from the flexible heat transfer plate 36 and rises, as shown in FIG. The cold head cooling unit 25 is in a non-contact state where it does not contact the flexible heat transfer plate 36. The thermal switch 26 is turned off, and the thermal link between the cold head cooling unit 25 and the flexible heat transfer plate 27 is eliminated.

  Therefore, when the cryogenic refrigerator 14 stops and the refrigerator cold head 15 rises in temperature, the cold head cooling unit 25 rises and is disconnected from the flexible heat transfer plate 36 and is brought into a non-contact state. 26 is OFF.

  Thus, when the cryogenic refrigerator 14 stops and the refrigerator cold head 15 (refrigerator body) rises in temperature, the cold head cooling section 25 that is the refrigerator cooling stage rises and flexible heat transfer is performed. It is separated from the plate 36 and is in a non-contact state. Even if the temperature of the refrigerator cold head 15 rises, the thermal switch 26 is turned off, and the contact portion is in a non-contact state. As the temperature of the refrigerator cold head 15 rises, the amount of heat intrusion due to radiation from the cold head cooling section 25 where the temperature has risen can be reduced, and high thermal resistance can be achieved when the thermal switch 26 is OFF.

[Effect of the third embodiment]
In the third embodiment, in the contact portion of the thermal switch 26, the total contact area is the same as the case where the entire contact surfaces are united as a single body, and if divided closely, the thermal resistance can be reduced by reducing the contact portion gap. Can be planned. When the cryogenic refrigerator 14 is driven, particularly in the case of a contact portion with a large heat flow due to a large-capacity refrigerator, the effect of reducing the thermal resistance by dividing the contact surface of the contact portion is increased.

  In addition, since the contact thermal resistance per unit area is reduced, it is possible to minimize the total surface area of the contact portion, so when the refrigerator cold head 15 rises in temperature when the refrigerator is stopped, The amount of heat intrusion due to radiation can be reduced from the cold head cooling section (refrigerator cooling stage) where the temperature has risen, and high thermal resistance when the heat switch 26 is OFF can be achieved.

[Fourth Embodiment]
A fourth embodiment of the cryogenic container and the superconducting magnet apparatus will be described with reference to FIGS. 7 and 8.

  7 and 8 are schematic configuration diagrams illustrating a fourth embodiment of the cryogenic container 10C. The cryogenic container 10C includes a plurality of cryogenic refrigerators 14A, for example, a main refrigerator 40 and an auxiliary refrigerator 41, in a heat insulating vacuum container 11A as a cryostat, while a radiation shield container 43 is provided in the heat insulating vacuum container 11A. Installed. The object to be cooled 12 is stored in the radiation shield container 43. When the object to be cooled 12 is a super heat transfer coil, the cryogenic container 10C is configured as a superconducting magnet device. The superconducting coil is wound around a winding frame (not shown) and stored.

  In describing the cryogenic container 10C or the superconducting magnet apparatus shown in the fourth embodiment, the same components as those in the cryogenic container 10 or the superconducting magnet apparatus of the first embodiment are denoted by the same reference numerals, and redundant description is given. Omitted or simplified.

  In the cryogenic container 10C or the superconducting magnet apparatus of the fourth embodiment, FIG. 7 is a schematic configuration diagram showing a state where the thermal switch 26 is ON, and FIG. 8 is a schematic configuration diagram showing a state where the thermal switch 26 is OFF. The cryogenic refrigerator 14A installed in the heat insulating vacuum vessel 11A of the cryogenic vessel 10C includes a main refrigerator 40 and an auxiliary refrigerator 41 having a multistage cooling stage. The main refrigerator 40 is installed on the heat transfer plates 27 and 45 so as to constantly cool the cooled object 12. The heat transfer plates 27 and 45 constitute a part of the body 12 to be cooled, and one is connected to the heat transfer plate 27 on which the body 12 to be cooled is mounted by a flexible heat transfer plate 45 in a cantilever shape. .

  The main refrigerator 40 constitutes a multistage cooling stage, and a first cooling stage (cold head cooling section) 46 is connected to the radiation shield container 43 to cool the shield container, while the second stage cooling stage ( The cold head cooling unit (47) is connected to a flexible heat transfer plate 45, and cools the cooled object (superconducting coil) 12 via the heat transfer plate 27 and keeps it at an extremely low temperature.

  The auxiliary refrigerator 41 constitutes a refrigerator cold head and, like the main refrigerator 40, constitutes a multistage cooling stage. The first-stage cold head cooling section 48 is positioned in the heat insulating vacuum container 11A, while the second-stage cold head cooling section 49 extends into the radiation shield container 43 and terminates. The second-stage cold head cooling unit 49 faces the heat transfer plate 27 that is a part of the cooled object 12. A spring / displacement mechanism 30 is provided between the second-stage cold head cooling section 49 and the heat transfer plate 27.

  In the spring / displacement mechanism 30, a coil spring which is guided by a guide post and expands and contracts is interposed between and in contact with the second-stage cold head cooling portion 49 and the heat transfer plate 27. When the heat transfer function of the coil spring of the spring / displacement mechanism 30 is not sufficient, a flexible heat transfer plate 33 is interposed between the heat transfer plate 27 and the second-stage cold head cooling unit 49. The heat transfer plate 33 is configured to be capable of being pressed into contact with the second-stage cold head cooling unit 49 side by the elastic force of the spring / displacement mechanism 30.

  A contact portion of the heat switch 26 is configured between the second-stage cold head cooling portion 49 of the auxiliary refrigerator 41 constituting the refrigerator cold head and the flexible heat transfer plate 33.

  The contact portion of the thermal switch 26 is configured such that the opposing contact surfaces are detachable, and the opposing contact surfaces are in contact when the thermal switch 26 is ON. When the thermal switch 26 is OFF, the opposing contact surfaces are in a non-contact state, and a gap is formed between the opposing contact surfaces.

  When the thermal switch 26 is OFF, a movable radiation shield plate 50 is provided in a gap formed between the contact surfaces facing each other in the contact portion so as to be able to be put in and out. The movable radiation shield plate 50 may be manually inserted and removed by rotating the operation rod 51, or the operation rod 51 may be linked directly to the motor operation of the cold head vertical control motor 23 or via a speed reduction mechanism. . When the cold head vertical control motor 23 is interlocked, when the thermal switch 26 is turned on, an inoperative position retracted from the contact portion of the thermal switch 26 is taken, and when the thermal switch 26 is turned off, between the contact portions of the thermal switch 26 is taken. It is adjusted to take the operating position to enter the gap.

  When the heat switch 26 is OFF, the movable radiation shield plate 50 closes the opening of the radiation shield container 43, seals and shields the inside of the radiation shield container 43, and radiant heat from the cold head cooling units 48 and 49 of the auxiliary refrigerator 41. Is transmitted to the cooled object 12 side.

[Operation of Fourth Embodiment]
In the cryogenic container 10C or the superconducting magnet apparatus shown in the fourth embodiment, when the cryogenic refrigerator 14A is activated, the auxiliary refrigerator 41, which is a refrigerator cold head, is driven as shown in FIG. By operating the auxiliary refrigerator 41, the cold head up / down control motor 23 is operated to lower the auxiliary refrigerator 41, to move the cold head cooling units 48 and 49 downward, and to make the second stage cold head cooling unit 49 flexible. The heat switch 26 is brought into contact with the heat transfer plate 33 and the heat switch 26 is kept in the ON contact state. With this configuration, the inside of the heat insulating vacuum container 11A is rapidly cooled by the main refrigerator 40 and the auxiliary refrigerator 41, and the object to be cooled 12 stored in the radiation shield container 43 is rapidly cooled in the heat insulating vacuum container 11A. It becomes a low-temperature cooling state.

  When the object to be cooled 12 is cooled in the normal state, the thermal switch 26 in FIG. 8 is set to the OFF state. At that time, the auxiliary refrigerator 41 is stopped, and this stop state is detected by the feed detection relay 22 that the auxiliary refrigerator 41 is not driven, and the cam mechanism 28 and the like are operated by the cold head vertical control motor 23. The auxiliary refrigerator 41 is pushed up. As the auxiliary refrigerator 41 is raised, the cold head cooling units 48 and 49 are pushed up and separated from the heat transfer plate 27 and the flexible heat transfer plate 33, and the second stage cold head cooling unit 49 is set to the flexible heat transfer plate 33. Is not in contact with the heat switch 26, and the thermal switch 26 is turned off.

  When the heat switch 26 is turned off, a gap is formed between the contact portions of the heat switch 26, the movable radiation shield plate 50 enters the gap portion, and the radiation shield plate 50 is set to the operating position. . The radiation shield container 43 is shielded by the movable radiation shield plate 50, and the radiation shield container 43 is sealed in the heat insulating vacuum container 11A.

  When the cryogenic refrigerator 14A is cooled by the main refrigerator 40 and the auxiliary refrigerator 41, the movable radiation shield plate 50 is removed from the gap portion of the contact portion of the thermal switch 26, and the thermal switch 26 is removed as shown in FIG. As shown in FIG.

  In the cryogenic container 10C or the superconducting magnet device of the fourth embodiment, the cryogenic refrigerator 14A is configured as shown in FIGS. 7 and 8 without removing the main refrigerator 40 and the auxiliary refrigerator 41. One refrigerator operation and two operation are possible.

  In the cryogenic container 10C or the superconducting magnet apparatus of the fourth embodiment, when the initial cooling of the heavy object to be cooled 12 or the superconducting coil that is the object to be cooled 12 is quenched and the temperature of the superconducting coil rises. In addition, it is possible to simultaneously drive a plurality of refrigerators to shorten the re-cooling time and to shorten the cooling time by the plurality of refrigerators.

  Further, after the cryogenic container 10C or the superconducting magnet device is cooled to a steady state, the heat switch 26 of the left refrigerator of FIGS. 7 and 8 as the auxiliary refrigerator 41 is turned OFF, and the heat switch 26 is contacted. It is possible to shield the radiation shield container 43 by allowing the movable radiation shield plate 50 to enter the gap portion between the portions. By shielding the radiation shield container 43, the amount of radiant heat penetration can be reduced, and the cooled object 12, particularly the superconducting coil, can be cooled stably.

  Furthermore, at the time of steady operation, the cryogenic refrigerator 14A can keep the cooled object 12 in an extremely low temperature state by operating one refrigerator, and can reduce power consumption for efficient operation and operation. Can do.

[Effect of Fourth Embodiment]
In the cryogenic container or superconducting magnet apparatus of the fourth embodiment, the movable auxiliary shield plate 50 causes the (auxiliary) refrigerator 41 to stop and radiate within the heat insulating vacuum container 11A when the cryogenic refrigerator 14A is stopped. The shield container 43 can be shielded to prevent radiant heat from entering from the auxiliary refrigerator 41 whose temperature is rising. In the case where the body 12 to be cooled is a superconducting coil, the cooling temperature can be lowered and the energization characteristics can be improved.

  In addition, when a plurality of refrigerators 40 and 41 are installed in the heat insulating vacuum vessel 11A and the initial cooling of the cooled object 12 and the superconducting coil as the cooled object 12 are quenched, the plurality of refrigerators 40 and 41 are used. Can be driven, the recooling time can be shortened, and the cooling time of the plurality of refrigerators 40 and 41 can be shortened.

  Furthermore, after the cryogenic vessel 10C or the superconducting magnet device is cooled to a steady state, the heat switch 26 as the auxiliary refrigerator 41 is turned off, and the movable radiation shield plate 50 is inserted into the gap portion between the contact portions, By shielding the radiation shield container 43, the amount of radiant heat entering the radiation shield container 43 is reduced, and the superconducting coil that is the object to be cooled 12 can be stably cooled. In addition, power consumption can be reduced for efficient operation and operation for the operation of one refrigerator during steady operation.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10,10A, 10B, 10C ... Cryogenic container (superconducting magnet device), 11, 11A ... Adiabatic vacuum vessel, 12 ... Cooled body (superconducting coil), 14, 14A ... Cryogenic refrigerator, 15 ... Refrigerator cold head , 16 ... Container lid, 17 ... Bellows (partition wall), 18 ... Installation base, 20 ... Drive cable, 21 ... Drive current source, 22 ... Feed detection relay, 23 ... Cold head vertical control motor, 25 ... Cold head cooling section (Cooling stage), 26 ... heat switch, 27 ... heat transfer plate, 28 ... cam mechanism, 29 ... guide post, 30, 35 ... spring / displacement mechanism, 33, 36 ... flexible heat transfer plate, 40 ... main refrigerator , 41 ... auxiliary refrigerator (refrigerator cold head), 43 ... radiation shield container, 45 ... heat transfer plate (flexible heat transfer plate), 46 ... first cooling stage, 47 ... Stage cooling stage, 48 ... first-stage cold head cooling unit (cooling stage), 49 ... 2-stage cold head cooling unit (cooling stage), 50 ... movable radiation shield plate, 51 ... operating rod.

Claims (13)

A heat-insulated vacuum container that houses the object to be cooled;
Having a cold machine cold head installed in this insulated vacuum vessel,
The refrigerator cold head has a cold head cooling section extending in the heat insulating vacuum vessel,
The refrigerator cold head is configured such that the cold head cooling unit presses against a part of the object to be cooled with a predetermined surface pressure due to a differential pressure between the atmospheric pressure outside the heat insulating vacuum vessel and the vacuum inside the heat insulating vacuum vessel. A contact part is formed by contact,
The cryocooler is characterized in that the cold head cooling unit is separated from a part of the cooled body when the refrigerator is stopped, and the cooled body is held in an independent non-contact state. . When the refrigerator is stopped, a force that resists the differential pressure between the atmospheric pressure outside the insulated vacuum vessel and the vacuum inside the insulated vacuum vessel is applied to the refrigerator cold head,
The cryogenic container according to claim 1, wherein a cold head cooling portion of the refrigerator cold head is held in a non-contact state with a part of the object to be cooled. The cryogenic container according to claim 1 or 2, wherein a contact portion where the cold head cooling portion of the refrigerator cold head comes into contact with a part of the object to be cooled is detachably contacted with each other. . A contact part between the cold head cooling part of the refrigerator cold head and a part of the object to be cooled constitutes a thermal switch, and the thermal switch eliminates a difference in flatness between contact surfaces of the contact part. The cryogenic container according to any one of claims 1 to 3, wherein the surface direction of at least one contact surface is changeable and is in surface contact with the other contact surface. The thermal switch is provided with a surface change mechanism for changing a surface direction of the contact surface in a cold head cooling unit of the refrigerator cold head so as to eliminate a gap due to a difference in flatness between contact surfaces of the contact unit,
The cryogenic container according to claim 4, wherein a contact surface of the thermal switch on a cold head cooling part side is connected to the cold head cooling part by a flexible heat transfer member. The cryogenic container according to any one of claims 1 to 5, wherein the contact portions are mirror-finished on both contact surfaces. The cryogenic container according to any one of claims 1 to 5, wherein the contact portion is configured as a contact surface in which one of the contact surfaces is finished to have a larger surface roughness than the other contact surface. The cryogenic container according to any one of claims 1 to 7, wherein at least one of the contact portions is provided with means for locally annealing to soften the work hardened layer on the contact surface in the heat insulating vacuum container. One of the contact portions includes a plurality of contact surfaces,
When the plurality of contact surfaces contact the other contact surface of the contact portion, the surface direction of the plurality of contact surfaces is set so as to eliminate a gap due to a difference in flatness between the contact surfaces of the contact portion. The cryogenic container according to any one of claims 1 to 3, further comprising a surface changing mechanism in surface contact with the other contact surface. 10. The superconducting magnet apparatus according to claim 1, wherein a superconducting coil is stored in the heat insulating vacuum container as the object to be cooled. A refrigerator and a main refrigerator are provided in an insulated vacuum vessel,
The object to be cooled is stored in a radiation shield container provided in the heat insulating vacuum container,
The main refrigerator is installed on a heat transfer plate so as to constantly cool the cooled object,
The refrigerator is configured with a contact portion that allows a cold head cooling portion, in which a refrigerator cold head extends into the heat insulating vacuum vessel, to come into contact with a part of the object to be cooled, so as to be detachable.
The contact portion of the refrigerator cold head is configured so that the cold head cooling unit applies a predetermined surface pressure to a part of the object to be cooled by a differential pressure between an atmospheric pressure outside the heat insulating vacuum vessel and a vacuum inside the heat insulating vacuum vessel. And press contact
The refrigerator cold head has a cryogenic temperature characterized in that when the refrigerator is stopped, the cold head cooling unit is separated from a part of the cooled object, and a part of the cooled object is held in a non-contact state. container. The contact part that contacts the cold head cooling part so as to be detachable from a part of the body to be cooled constitutes a thermal switch,
In the thermal switch, when the contact surfaces of the contact portions are in the non-contact state OFF, the operation position where the radiation shield plate is inserted into the gap between the contact portions of the thermal switch and the contact surfaces of the contact portions are in contact with each other. The cryogenic container according to claim 11, wherein the radiation shield plate is operated so as to be movable between an inoperative position separated from a contact portion of the thermal switch when the power is turned on. The superconducting magnet apparatus according to claim 11 or 12, wherein a superconducting coil is stored as a body to be cooled in a radiation shield container in a heat insulating vacuum container.

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