JP2009146934A - Cryostat for superconducting electromagnet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the blockade of a helium gas exhaust pipe, and to quickly remove the blockade thereof. <P>SOLUTION: A cryostat is provided with a supply pipe 11, which is installed along the pipe route of a helium gas exhaust gas pipe 10 communicated with air side of the outside of a vacuum vessel and can supply helium gas to at least the upstream side, in a direction of exhausting the helium gas out of the helium gas exhaust pipe 10. The supply pipe 11 is provided with a plurality of supply ports 11a-11d for feeding helium gas to the helium gas exhaust pipe 10 at a predetermined spacing in the direction of the pipe route, wherein differential pressure regulating valves 21a-21d are provided at the supply ports 11a-11d, and they are opened, when the differential pressure between the helium gas exhaust pipe 10 and the supply pipe 11 exceeds a predetermined value, and they feed the helium gas to the helium gas exhaust pipe 10 from the supply pipe 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cryostat for a superconducting electromagnet.

A superconducting coil applied to a cryostat for a superconducting electromagnet is cooled with a liquefied refrigerant, such as liquid helium, for cooling it to a critical point or less. The superconducting coil and liquid helium are stored in a liquid helium container, and the liquid helium container is stored in a vacuum container that forms an adiabatic vacuum layer. A heat shield is installed between the liquid helium vessel and the vacuum vessel, and the liquid helium vessel is further insulated and protected by this heat shield.
In addition, the liquid helium container is appropriately provided with an injection tube for injecting liquid helium into the liquid helium container, and a helium gas exhaust pipe for discharging the helium gas in the liquid helium container out of the liquid helium container. Yes.

By the way, when the superconducting coil is energized to generate a magnetic field, a part of the coil conductor of the superconducting coil moves, or a crack occurs in an impregnation material such as an epoxy resin covering the coil conductor. When a mechanical disturbance occurs, this becomes a thermal disturbance, and a temperature of a part of the superconducting coil rises and transitions to normal conduction. When the temperature rise due to such thermal disturbance greatly exceeds the cooling by the surrounding liquid helium, a phenomenon in which the normal conduction transition reaches the entire superconducting coil and the magnetic field disappears, so-called quenching occurs.
When such a quench occurs, the coil temperature rises due to Joule heat generation, and the liquid helium used for cooling is rapidly vaporized to generate a large amount of helium gas, so that the pressure inside the liquid helium container rises rapidly.
Conventionally, in order to suppress the pressure rise inside the liquid helium container, a rupture plate is provided in the helium gas discharge pipe so that helium gas is discharged to the outside of the vacuum container through the helium gas discharge pipe. (See, for example, Patent Document 1).

  The cryostat for a superconducting electromagnet is inhaled when the pressure in the liquid helium container becomes negative with respect to the atmospheric pressure when replenishing liquid helium or replacing the installed refrigerator. In order to avoid this, a structure has been proposed in which a heater is arranged in liquid helium so that the pressure in the liquid helium container is always positive (for example, see Patent Document 2).

JP-A-5-55032 JP 2007-19520 A

  As described above, in the conventional cryostat for a superconducting electromagnet, when the occurrence of a quench, the rupture plate of the helium gas discharge pipe is ruptured, and the pressure increase inside the liquid helium container is suppressed, If the internal pressure of the liquid helium container decreases as helium gas is discharged and becomes negative with respect to the atmospheric pressure, air may be sucked through the helium gas discharge pipe communicated to the atmosphere side. On the side close to the liquid helium container, the helium gas discharge pipe is at a sufficiently low temperature to freeze the air. Therefore, when air is inhaled as described above, the helium gas discharge pipe is frozen in the middle of the helium gas discharge pipe. May cause occlusion.

  In addition, when the refrigerator is operated after quenching, it is possible to vaporize the liquid helium with a heater provided in the liquid helium container and keep the liquid helium container at a positive pressure, but the amount of heat of the heater is insufficient. As helium gas is condensed by cooling and becomes negative pressure, there is a possibility of clogging due to air inhalation.

  When such a blockage occurs, it becomes impossible to discharge the helium gas to be vaporized by heat entering through the power lead when exciting the superconducting coil, or in the liquid helium container when replenishing liquid helium. The helium gas in the gas layer cannot be discharged, which hinders the operation of the superconducting electromagnet.

  From such a viewpoint, the present invention prevents the helium gas discharge pipe from being blocked, and even if a blockage occurs, the blockage can be quickly removed, which hinders the operation of the superconducting electromagnet. It is an object of the present invention to provide a cryostat for a superconducting electromagnet that can be avoided.

  As a means for solving the above-described problems, the present invention provides a supply pipe that is provided along a pipe line of a helium gas discharge pipe and can supply helium gas at least upstream in the helium gas discharge direction of the helium gas discharge pipe. The supply pipe is provided with a plurality of supply ports for supplying helium gas to the helium gas discharge pipe at a predetermined interval in the pipe line direction. A differential pressure valve that opens when the differential pressure between the helium gas discharge pipe and the supply pipe exceeds a predetermined value and allows the supply of helium gas from the supply pipe to the helium gas discharge pipe is provided. It was. As a result, when the differential pressure between the helium gas exhaust pipe and the supply pipe exceeds a predetermined value after quenching or the like, helium gas is supplied from the supply pipe to the helium gas exhaust pipe via each differential pressure valve, and the helium gas exhaust pipe is upstream. Filled with helium gas from the side. In addition, even when clogging occurs, a plurality of supply ports are provided at predetermined intervals in the pipe line direction, so that helium gas can be continuously supplied to the vicinity of the clogging portion, and freezing is thawed. Can eliminate the blockage.

  According to the present invention, it is possible to prevent clogging of the helium gas discharge pipe, and even if clogging occurs, the clogging can be quickly removed so as not to hinder the operation of the superconducting electromagnet. A cryostat for a superconducting electromagnet can be obtained.

Hereinafter, embodiments of the cryostat for a superconducting electromagnet of the present invention will be described in detail with reference to the drawings.
(First embodiment)
As shown in FIG. 1, a cryostat 1 for a superconducting electromagnet according to the first embodiment includes a liquid helium container 4 that houses a superconducting coil 2 together with liquid helium 3, a radiation shield 5 that is formed so as to cover the liquid helium container 4, and a liquid The vacuum vessel 6 includes a helium vessel 4 and a radiation shield 5 and is composed of a vacuum vessel 6 or the like in which the inside is evacuated, and a refrigerator 7 for cooling the liquid helium 3 and the radiation shield 5 is installed in the vacuum vessel 6.

  The liquid helium container 4 is formed of a sealable container and serves as a tank that stores the liquid helium 3. The liquid helium container 4 is connected to a liquid helium injection pipe 13 for injecting the liquid helium 3 into the liquid helium container 4, and the gas phase state inside the liquid helium container 4 is also connected. Helium gas discharge pipe 10 for discharging the helium gas is connected.

  The vacuum container 6 is a container sealed from the atmosphere, and the space between the liquid helium container 4 and the liquid helium container 4 can be evacuated by a vacuum pump. And the liquid helium container 4 is thermally insulated by the vacuum layer which became this vacuum state. Further, the radiation shield 5 is insulated by blocking the radiation heat to the liquid helium container 4, and is installed in the vacuum layer in the vacuum container 6.

  The refrigerator 7 includes a cooling head 7a installed so as to penetrate from the outside of the vacuum vessel 6 to the gas phase of the liquid helium vessel 4, a compressor 7b for compressing the refrigerator refrigerant, and between the cooling head 7a and the compressor 7b. The refrigerant circulation path 7c for circulating the refrigerant for the refrigerator is formed. The cooling head 7a cools and liquefies the helium gas vaporized in the liquid helium container 4, and also cools the radiation shield 5. A heater 8 is installed in the liquid phase of the liquid helium container 4. The heater 8 controls the internal pressure of the liquid helium container 4 by appropriately vaporizing the liquid helium 3 so that the inside of the liquid helium container 4 does not become a negative pressure with respect to the atmospheric pressure due to cooling by the refrigerator 7.

One end side of the liquid helium injection pipe 13 communicates with the liquid helium container 4 and extends to the vicinity of the bottom, and the other end side extends to the outside of the vacuum container 6 and is closed by a valve 14.
The helium gas discharge pipe 10 has one end communicating with the liquid helium container 4 and the other end guided outside the vacuum container 6, for example, outside the chamber (not shown) and communicated with the atmosphere side. The helium gas discharge pipe 10 is arranged so as to meander in the vacuum container 6 so that the pipe length becomes long in order to reduce the amount of heat input to the liquid helium container 4 by conduction.

  The helium gas discharge pipe 10 is provided with a differential pressure valve 15 and a rupturable plate 16 as discharge means in the middle of the pipe line outside the vacuum vessel 6. The differential pressure valve 15 and the rupture plate 16 are opened when the internal pressure of the liquid helium container 4 exceeds a set value (the rupture plate 16 is ruptured), communicate with the pipe line, and discharge the vaporized helium gas to the atmosphere side to form a liquid. It serves to lower the internal pressure of the helium container 4. Therefore, normally, the differential pressure valve 15 and the rupturable plate 16 are closed, and the liquid helium container 4 is held in a sealed state.

The helium gas discharge pipe 10 is provided with a supply pipe 11 for supplying helium gas, which is a characteristic configuration of the present invention.
As shown in FIG. 2, the supply pipe 11 is formed of helium gas from an outer part 10 a of the vacuum vessel 6 (a part at a normal temperature of the helium gas discharge pipe 10) on the downstream side in the helium gas discharge direction in the helium gas discharge pipe 10. It is provided over the vicinity 10b of the connection portion between the liquid helium container 4 and the helium gas discharge pipe 10 on the upstream side in the discharge direction, so that helium gas can be supplied mainly to the upstream side of the helium gas discharge pipe 10. Is provided. In the present embodiment, substantially the entire supply pipe 11 is contained in the helium gas discharge pipe 10.

On the upstream side of the helium gas discharge pipe 10, a plurality of supply ports 11a to 11d for supplying helium gas to the helium gas discharge pipe 10 are provided at predetermined intervals in the pipe line direction. In the present embodiment, supply ports 11 a to 11 d are provided from the vicinity of the connecting portion 10 b to the periphery of the U-shaped folded portion 10 c on the upstream side of the helium gas discharge pipe 10. These supply ports 11a to 11d are respectively provided with differential pressure valves 21 (21a to 21d). The differential pressure valves 21a to 21d are opened when the differential pressure between the helium gas discharge pipe 10 and the supply pipe 11 exceeds a predetermined value, so that the supply of helium gas from the supply pipe 11 to the helium gas discharge pipe 10 is allowed. It has become.
A helium gas cylinder 20 is connected to the end of the supply pipe 11 via a valve 19. That is, normal temperature helium gas is directly supplied to the supply pipe 11 from a helium gas cylinder 20 disposed outside the vacuum vessel 6.

Next, the operation of the thus-configured superconducting electromagnet cryostat 1 will be described.
When the internal pressure of the liquid helium container 4 increases due to the occurrence of a quench or the like and the differential pressure valve 15 or the rupture plate 16 provided in the helium gas discharge pipe 10 is opened, the valve 19 of the supply pipe 11 is opened, Helium gas is supplied from the helium gas cylinder 20 to the supply pipe 11. Thereafter, when the internal pressure of the liquid helium container 4 decreases and the differential pressure between the helium gas discharge pipe 10 and the supply pipe 11 exceeds a predetermined value, the differential pressure valves 21a to 21d are opened, and the helium gas from the supply pipe 11 is opened. Helium gas is supplied to the discharge pipe 10. As a result, the helium gas discharge pipe 10 is filled with the normal-temperature helium gas supplied through the supply pipe 11, and the temperature of the wide area of the pipe line is increased with the supplied helium gas, and the differential pressure valve 15 in the communication state is provided. Further, air can be prevented from entering from the outside air via the rupturable plate 16. This prevents the occurrence of clogging due to freezing in the helium gas discharge pipe 10.

Here, if the clogging due to freezing has occurred in the helium gas discharge pipe 10 before the helium gas is supplied from the helium gas cylinder 20 to the supply pipe 11, the helium gas is supplied to the supply pipe 11. By doing so, the following effects can be obtained.
That is, since the supply ports 11a to 11d are provided at predetermined intervals in the pipe line direction, for example, as shown in FIG. 2, the supply port 11a and the supply port 11b on the upstream side of the helium gas discharge pipe 10 are provided. If the closed portion 12 is caused by freezing, the supply port 11a is located in the closed space upstream of the closed portion 12 with the closed portion 12 as a boundary, and the supply ports 11b to 11d Is located in a space in the helium gas discharge pipe 10 communicating with the atmosphere side downstream of the blocking portion 12. When helium gas is supplied through the supply pipe 11 in this state, the internal pressure increases due to the helium gas supplied through the supply port 11a due to the closed space on the upstream side of the closed portion 12, and the differential pressure valve 21a. Is closed and the supply of helium gas is stopped. However, since it communicates with the atmosphere side downstream of the blocking portion 12, helium gas can be continuously supplied through the supply ports 11b to 11d. Due to the temperature rise effect of the supplied helium gas, the freezing in the closed portion 12 can be melted suitably.

  Assuming that the supply pipe 11 does not have such a plurality of supply ports 11a to 11d but has a structure having only one supply port, for example, the supply port 11a, the blocking portion 12 is connected to the supply port as described above. In the case where it is located on the downstream side of 11a, the space where the supply port 11a is located becomes a space closed by the closing portion 12, so that the amount of helium gas supplied from the supply port 11a is limited. Therefore, the temperature rise effect due to continuous supply cannot be obtained. That is, freezing of the closed portion 12 is difficult to thaw.

  On the other hand, in this embodiment, since the plurality of supply ports 11a to 11d are provided at predetermined intervals in the pipe line direction, even if the blockage part 12 due to freezing occurs in the pipe line, the blockage part The supply port 11b to the supply port 11d are located in a portion communicating with the atmosphere on the downstream side with reference to 12, and helium gas can be continuously supplied through these supply ports 11b to 11d. Therefore, the freezing of the closed portion 12 can be suitably thawed by the temperature rise effect of the supplied helium gas.

Below, the effect acquired in this embodiment is demonstrated.
(1) The helium gas discharge pipe 10 can be filled with normal-temperature helium gas supplied through the supply pipe 11, and air can be prevented from entering the helium gas discharge pipe 10 after quenching or the like.
(2) It is possible to raise the temperature of the helium gas discharge pipe 10 with room temperature helium gas supplied through the supply pipe 11 and to prevent the helium gas discharge pipe 10 from being blocked by freezing. Can do.
(3) Since the plurality of supply ports 11a to 11d are provided at predetermined intervals in the pipe line direction, helium gas is supplied to the helium gas discharge pipe 10 that communicates with the atmosphere side that is downstream from the closed portion 12. It can supply continuously and the freezing of the obstruction | occlusion part 12 can be thawed suitably. Therefore, there is no need for a means for thawing freezing by providing a heater or the like, and wiring for that is unnecessary, and the structure is simplified.
In addition, the helium gas discharge pipe 10 can be heated over a wide range with the helium gas supplied from the supply pipe 11, and the helium gas discharge pipe 10 can be warmed more efficiently than when heating means such as a heater is used. Therefore, it is possible to prevent obstruction due to freezing. In addition, even if the blockage occurs, the temperature in the vicinity of the blockage portion 12 can be efficiently raised and freezing can be quickly eliminated.
(4) Since the differential pressure valves 21a to 21d are provided in the supply ports 11a to 11d, helium gas discharge pipe 10 is preferably connected to helium gas discharge pipe 10 in a state where the internal pressure of helium gas discharge pipe 10 has decreased after quenching or the like. Gas can be supplied. Therefore, it is possible to prevent the occurrence of clogging due to freezing in the helium gas discharge pipe 10 without waste.
(5) Since the supply pipe 11 is included in the helium gas discharge pipe 10, there is no need to provide an insertion hole for the supply pipe 11 in the upper part of the vacuum vessel 6, and there are no pipe connection locations inside the vacuum vessel 6. As a result, the degree of vacuum can be prevented from being reduced.

(Second Embodiment)
As shown in FIG. 3, the superconducting electromagnet cryostat 1 according to the second embodiment has a configuration in which the entire pipeline of the supply pipe 11 </ b> A is disposed outside the helium gas discharge pipe 10. Then, supply ports 11 a to 11 d having differential pressure valves 21 a to 21 d are opened at a predetermined interval in the pipe line direction of the helium gas discharge pipe 10.

  According to the cryostat 1 for a superconducting electromagnet as described above, not only the effects (1) to (4) described in the first embodiment are obtained, but also the supply pipe 11 is provided along the outside of the helium gas discharge pipe 10. Since it should just arrange | position, the effect that construction regarding installation of the supply pipe | tube 11 is comparatively easy is acquired. In addition, since the supply pipe 11 is not exposed to the cryogenic helium gas discharged from the liquid helium container 4, it becomes possible to supply helium gas to the vicinity of the closed portion 12 at a higher temperature. Thereby, it becomes possible to melt | dissolve the freezing of the obstruction | occlusion part 12 rapidly, and to eliminate obstruction | occlusion.

(Third embodiment)
As shown in FIG. 4, the superconducting electromagnet cryostat 1 according to the third embodiment recirculates a portion of the helium gas downstream in the helium gas discharge direction in the helium gas discharge pipe 10 to the upstream side of the helium gas discharge pipe 10. The difference from the first and second embodiments is that a recirculation device 25 for circulation is provided.

  The recirculation device 25 has one end communicating with the downstream helium gas discharge pipe 10 so that helium gas can be introduced and the other end communicating with the supply pipe 11 and the communication pipe 22. A valve 24 and a pump 23 which is provided in the middle of the communication pipe 22 and sends out helium gas introduced from the downstream helium gas discharge pipe 10 toward the supply pipe 11 are provided.

  In such a superconducting electromagnet cryostat 1, when the internal pressure of the liquid helium container 4 rises due to a quench phenomenon or the like and the differential pressure valve 15 or the rupture plate 16 of the helium gas discharge pipe 10 opens, the valve 24 is opened. The pump 23 is operated, and the helium gas heated while passing through the helium gas discharge pipe 10 from the upstream side to the downstream side is supplied to the supply pipe 11 through the communication pipe 22, and the helium gas discharge pipe 10 is supplied from the supply pipe 11. To the upstream side. Thereby, helium gas can be recirculated in the helium gas discharge pipe 10. As a result, the temperature of the wide area of the pipeline can be raised, air can be prevented from entering, and blockage can be prevented from occurring.

  Further, when the blockage occurs, the valve 24 is closed, the pump 23 is stopped, and the valve 19 is opened. Thus, the same effect as that of the first embodiment can be obtained, and normal temperature helium supplied from the helium gas cylinder 20 is obtained. It becomes possible to quickly eliminate the blockage caused by the freezing of the pipeline with the gas.

  As described above, the superconducting electromagnet cryostat 1 according to the present embodiment recirculates the helium gas that has been heated while leaving the liquid helium container 4 and passing through the helium gas discharge pipe 10, thereby increasing the range of the pipeline. It can be heated, and air can be prevented from entering to prevent obstruction. Even if air enters the helium gas discharge pipe 10 and the pipe is closed, helium gas at normal temperature can be continuously supplied to the vicinity of the closed portion 12 as in the first embodiment. In addition, the temperature of the pipe line can be increased, and the freezing can be thawed to eliminate the blockage. Thereby, the cryostat 1 for superconducting electromagnets which does not interfere with the operation of the superconducting electromagnet can be obtained.

(Fourth embodiment)
The cryostat 1 for a superconducting electromagnet of the fourth embodiment includes a control unit 30 for automatically preventing the helium gas discharge pipe 10 from being blocked and eliminating the operation when the helium gas discharge pipe 10 is blocked. This is different from the first to third embodiments.

As shown in FIG. 5, a pump 23, valves 19, 24, a differential pressure valve 15, and a rupturable plate 16 are electrically connected to the control unit 30 via a wiring 31, and the control unit 30 includes a differential pressure valve 15, By detecting the communication state of the rupturable plate 16, the opening / closing operation of the valves 19, 24 and the operation or stop of the pump 23 can be controlled.
More specifically, the control unit 30 controls the operation of the pump 23 and detects the downstream side of the helium gas discharge pipe 10 introduced through the communication pipe 22 when the communication between the differential pressure valve 15 and the rupturable plate 16 is electrically detected, for example. The helium gas is supplied to the supply pipe 11 and recirculated to the upstream side of the helium gas discharge pipe 10.

The superconducting electromagnet cryostat 1 includes a first pressure sensor 32 as a first detection means for detecting the internal pressure of the liquid helium container 4 and a second detection means for detecting the internal pressure of the downstream helium gas discharge pipe 10. As a second pressure sensor 33.
Then, the control unit 30 controls the operation of the valve 19 when a predetermined differential pressure is generated between the pressure P1 detected by the first pressure sensor 32 and the pressure P2 detected by the second pressure sensor 33. The helium gas cylinder 20 as helium supply means is controlled to supply helium gas to the supply pipe 11.

  Next, the operation will be described with reference to the flowchart of FIG. 6 and FIG. When the internal pressure of the liquid helium container 4 rises due to a quench or the like and the differential pressure valve 15 or the rupture disk 16 is opened (open is detected) (Yes in step S1), the control unit 30 opens the valve 24 and the valve 19 Is closed and the pump 23 is operated (step S2), and helium gas heated while passing through the helium gas discharge pipe 10 is supplied to the supply pipe 11 through the communication pipe 22, and the helium gas discharge pipe is supplied from the supply pipe 11 10 to the upstream side. Thereby, helium gas can be recirculated in the helium gas discharge pipe 10. As a result, the temperature of the wide area of the pipeline can be raised, air can be prevented from entering, and blockage can be prevented from occurring.

  Next, the control unit 30 determines whether or not the pressure P1 detected by the first pressure sensor 32 and the pressure P2 detected by the second pressure sensor 33 are the same, and determines that they are the same (step S3). In step S4, it is determined whether or not the pressure P1 of the liquid helium container 4 has been reduced to a pressure that can be sealed. If it is determined in step S4 that the pressure P1 of the liquid helium container 4 has decreased to a pressure that can be sealed (Yes in step S4), the process proceeds to step S5, where the control unit 30 closes the valve 24 and 19 is kept closed, and the pump 23 is controlled to stop. In this state, the liquid helium 3 is replenished through the liquid helium injection pipe 13 (see FIG. 1), and the liquid helium container 4 is sealed to finish.

  If it is determined in step S4 that the pressure P1 of the liquid helium container 4 has not decreased to a pressure that can be sealed (No in step S4), the process returns to step S2 and the following steps S3 and S4 are repeated.

  On the other hand, when the control unit 30 determines in step S3 that the pressure P1 detected by the first pressure sensor 32 and the pressure P2 detected by the second pressure sensor 33 are not the same (No in step S3). Shifts to step S6 to close the valve 24 and open the valve 19 to stop the pump 23. That is, it is determined that the helium gas discharge pipe 10 is clogged, and normal temperature helium gas is supplied from the helium gas cylinder 20 to the helium gas discharge pipe 10 through the supply pipe 11.

  In step S7, the control unit 30 determines whether or not the pressure P1 detected by the first pressure sensor 32 and the pressure P2 detected by the second pressure sensor 33 are the same, and determines that they are the same ( If it is determined in step S7 that the pressure P1 of the liquid helium container 4 has decreased to a pressure that can be sealed, and if it is determined that the pressure has decreased (Yes in step S8), In S5, the valve 19 is closed and the valve 24 is closed and the pump 23 is stopped. Then, the liquid helium 3 is replenished through the liquid helium injection pipe 13 (see FIG. 1), and the liquid helium container 4 is hermetically closed.

  If it is determined in step S7 that the pressure P1 and the pressure P2 are not the same (No in step S7), normal-temperature helium gas is discharged from the helium gas cylinder 20 until the pressure P1 and the pressure P2 are the same. The helium gas discharge pipe 10 is supplied from the supply pipe 11. If it is determined in step S8 that the pressure P1 of the liquid helium container 4 has not decreased to a pressure that can be sealed (No in step S8), steps S7 and S8 are repeated.

  As described above, the superconducting electromagnet cryostat 1 of the present embodiment can prevent the blockage by automatically raising the temperature of the pipe of the helium gas discharge pipe 10 and preventing air from entering even when a quench or the like occurs. it can. Further, even if air enters the helium gas discharge pipe 10 and the pipe line is closed, normal temperature helium gas can be continuously supplied to the vicinity of the closed part 12, and freezing is thawed to block the pipe. Can be resolved. Therefore, a cryostat 1 for a superconducting electromagnet that does not hinder the operation of the superconducting electromagnet can be obtained.

  In the embodiment, the helium gas is configured to be supplied mainly to the upstream side of the helium gas discharge pipe 10 through the supply pipe 11. However, the present invention is not limited to this, and helium disposed in the vacuum vessel 6 is used. You may comprise so that a supply port may be arrange | positioned at the whole gas exhaust pipe 10. FIG.

It is sectional drawing which showed typically schematic structure of the cryostat for superconducting electromagnets concerning 1st Embodiment of this invention. It is the sectional view which expanded the principal part of the cryostat for superconducting electromagnets similarly, and was shown typically. It is sectional drawing which expanded and showed typically the principal part of the cryostat for superconducting electromagnets concerning 2nd Embodiment of this invention. It is sectional drawing which expanded and showed typically the principal part of the cryostat for superconducting electromagnets concerning 3rd Embodiment of this invention. It is sectional drawing which expanded and showed typically the principal part of the cryostat for superconducting electromagnets concerning 4th Embodiment of this invention. It is a flowchart explaining an effect | action.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cryostat for superconducting magnets 2 Superconducting coil 3 Liquid helium 4 Liquid helium container 5 Radiation shield 6 Vacuum container 7 Refrigerator 10 Helium gas discharge pipe 10a Outer part 10b Near part 11 Supply pipe 11A Supply pipe 11a-11d Supply port 12 Blocking part 13 Liquid helium injection pipe 19 Valve 20 Helium gas cylinder 21 (21a to 21d) Differential pressure valve 22 Communication pipe 23 Pump 24 Valve 25 Recirculation device 30 Control unit 32 First pressure sensor 33 Second pressure sensor

Claims (7)

A liquid helium container storing liquid helium for cooling the superconducting coil, a vacuum container containing the liquid helium container for vacuum insulation, one end communicating with the liquid helium container, and the other end of the vacuum container A helium gas exhaust pipe communicating with the outside atmosphere side and a helium gas exhaust pipe outside the vacuum container are provided in the middle of the conduit, and when the internal pressure of the liquid helium container exceeds a set value, the helium gas exhaust pipe is In a cryostat for a superconducting electromagnet having a discharge means for discharging helium gas vaporized in communication to the atmosphere side,
Provided along a pipe line of the helium gas discharge pipe, and provided with a supply pipe capable of supplying helium gas at least upstream in the helium gas discharge direction of the helium gas discharge pipe,
The supply pipe is provided with a plurality of supply ports for supplying helium gas to the helium gas discharge pipe at predetermined intervals in the pipe line direction,
The plurality of supply ports open when the differential pressure between the helium gas discharge pipe and the supply pipe exceeds a predetermined value, and allow a supply of helium gas from the supply pipe to the helium gas discharge pipe. A cryostat for a superconducting electromagnet, which is provided with a pressure valve. The supply pipe is a connection portion between the liquid helium container and the helium gas discharge pipe that are located upstream in the helium gas discharge direction from the outer part of the vacuum container that is located downstream in the helium gas discharge direction in the helium gas discharge pipe. Is attached over the vicinity of
The cryostat for a superconducting electromagnet according to claim 1, wherein the plurality of supply ports are mainly provided on the upstream side.   The superconducting electromagnet cryostat according to claim 1, wherein at least a part of the supply pipe is included in the helium gas discharge pipe.   The superconducting electromagnet cryostat according to claim 1 or 2, wherein the supply pipe is entirely disposed outside the helium gas discharge pipe. A recirculation device for recirculating a part of the helium gas downstream of the helium gas discharge pipe in the helium gas discharge direction to the upstream side of the helium gas discharge pipe;
The recirculation device comprises:
A communication pipe having one end communicating with the helium gas discharge pipe on the downstream side and capable of introducing helium gas, and the other end communicating with the supply pipe;
2. The pump according to claim 1, further comprising: a pump that is provided in the middle of the communication pipe and that sends out helium gas introduced from the helium gas discharge pipe on the downstream side toward the supply pipe. The cryostat for a superconducting electromagnet according to any one of 4. A control unit for controlling the operation of the pump;
The control unit can detect communication of the helium gas discharge pipe by the discharge means, and when the communication is detected, operates the pump to downstream of the helium gas discharge pipe introduced through the communication pipe. 6. The superconducting electromagnet cryostat according to claim 5, wherein the helium gas is controlled to be sent to the supply pipe and recirculated to the upstream side of the helium gas discharge pipe. First detection means for detecting the pressure in the liquid helium container, second detection means for detecting the pressure in the downstream helium gas discharge pipe, and helium connected to the supply path via an opening / closing means A supply means,
The controller controls the operation of the opening / closing means when a predetermined differential pressure is generated between the pressure detected by the first detection means and the pressure detected by the second detection means. The superconducting electromagnet cryostat according to any one of claims 1 to 6, wherein helium gas is controlled to be supplied from the helium supply means to the supply path.

Images