JP2007005552A - Cryostat for superconducting magnet - Google Patents

Cryostat for superconducting magnet Download PDF

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JP2007005552A
JP2007005552A JP2005183613A JP2005183613A JP2007005552A JP 2007005552 A JP2007005552 A JP 2007005552A JP 2005183613 A JP2005183613 A JP 2005183613A JP 2005183613 A JP2005183613 A JP 2005183613A JP 2007005552 A JP2007005552 A JP 2007005552A
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liquid helium
liquid
helium tank
superconducting magnet
tank
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JP4537270B2 (en
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Toshiyuki Shiino
俊之 椎野
Minseok Park
ミンソク 朴
Yoshihide Wadayama
芳英 和田山
Michiya Okada
道哉 岡田
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Hitachi Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a cryostat for a superconducting magnet remarkably reducing the possibility of the discharge of a current lead for the superconducting magnet by a structure in which the current lead is not exposed to saturated steam. <P>SOLUTION: An upward projection is formed at a part of the upper section of a saturated superfluid helium tank 5, and the current lead 15 for the superconducting magnet 14 is introduced into the helium tank 5 from the upper section being a projection. A valve controller 20 controls an exhaust pipe valve 12 and a flow control valve 13 so that the surface of the liquid of saturated superfluid helium is positioned at the specified place of the projection. Accordingly, the possibility of the discharge can be reduced remarkably without exposing the current lead 15 to saturated steam. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、超電導磁石の冷却に用いられるクライオスタットに係り、特に飽和超流動ヘリウムクライオスタットに関する。   The present invention relates to a cryostat used for cooling a superconducting magnet, and more particularly to a saturated superfluid helium cryostat.

大気圧下で４．２Ｋの液体ヘリウムは超電導磁石の冷却用冷媒として用いられる。この液体ヘリウムを排気装置により減圧すると、蒸気圧の降下とともに温度が下がり２．１７Ｋ以下で超流動状態になる。この状態の液体ヘリウムは飽和超流動ヘリウムと呼ばれる。   Under atmospheric pressure, 4.2K liquid helium is used as a cooling refrigerant for the superconducting magnet. When this liquid helium is depressurized by the exhaust device, the temperature decreases with a drop in vapor pressure and becomes superfluid at 2.17K or less. Liquid helium in this state is called saturated superfluid helium.

超電導磁石は運転温度が下がる程高磁界を発生させることがでる。また、超流動状態では４．２Ｋの時よりも熱輸送能力が高くなる。このような理由から、飽和超流動ヘリウムは高磁界発生用超電導磁石の冷媒として用いられてきた。   A superconducting magnet can generate a high magnetic field as the operating temperature decreases. In the superfluid state, the heat transport capability is higher than that at 4.2K. For this reason, saturated superfluid helium has been used as a refrigerant for superconducting magnets for generating high magnetic fields.

飽和超流動ヘリウムの生成装置は、特許文献１の記載のように、断熱真空容器内に４．２Ｋの液体ヘリウムを貯留する槽と飽和超流動ヘリウム槽が設置されていて、その二つの槽がＪＴ弁を介して連結している。４．２Ｋ液体ヘリウム槽から飽和超流動ヘリウム槽へＪＴ弁を介して液体ヘリウムを供給して、それを排気装置で減圧することにより飽和超流動ヘリウムを生成する。また、液面、温度を制御する制御装置を備えている。   As described in Patent Document 1, the saturated superfluid helium generator has a tank for storing 4.2K liquid helium and a saturated superfluid helium tank installed in an adiabatic vacuum vessel. It is connected via a JT valve. The liquid helium is supplied from the 4.2K liquid helium tank to the saturated superfluid helium tank via the JT valve, and the superheated helium is generated by reducing the pressure with an exhaust device. Moreover, the control apparatus which controls a liquid level and temperature is provided.

特許第２７６０８５８号公報Japanese Patent No. 2760858

従来技術による装置には、超電導磁石の電流リードが１．８Ｋ程度の液体ヘリウム飽和蒸気にさらされるために、放電の可能性があり、電流リード自身に放電対策を施さなければならなかった。   In the device according to the prior art, since the current lead of the superconducting magnet is exposed to liquid helium saturated vapor of about 1.8K, there is a possibility of discharge, and it has been necessary to take measures against the discharge of the current lead itself.

本発明の目的は、上記従来技術の問題点に鑑み、超電導磁石の電流リードが飽和蒸気にさらされない構造により、前記放電の可能性を著しく低減した超電導磁石用クライオスタットを提供することにある。   An object of the present invention is to provide a cryostat for a superconducting magnet in which the possibility of discharge is remarkably reduced by a structure in which the current lead of the superconducting magnet is not exposed to saturated vapor in view of the above-mentioned problems of the prior art.

上記課題の解決は、液体ヘリウムを貯留する第一の液体ヘリウム槽と、前記第一の液体ヘリウム槽と断熱真空により仕切られる第二の液体ヘリウム槽と、前記第一の液体ヘリウム槽と前記第二の液体ヘリウム槽を内包する断熱真空容器と、前記第二の液体ヘリウム槽内に設置される超電導磁石と、前記第一の液体ヘリウム槽と前記第二の液体ヘリウム槽とを連通する通路と、前記通路を通過する液体ヘリウムの流量を調節する流量調整弁と、前記第二の液体ヘリウム槽内の蒸発ヘリウムガスを排気する排気管と、前記排気管を通過する前記蒸発ヘリウムガスの流量を調節する排気管弁と、前記蒸発ヘリウムガスを排気する排気装置と、前記超電導磁石に電流を供給するための電流リードと、を有する超電導磁石用クライオスタットにおいて、前記電流リードが前記第二の液体ヘリウム槽に導入される位置が、前記第二の液体ヘリウム槽内にある液体ヘリウム液面よりも低い位置に設けられることを特徴として、達成される。   The solution of the above-mentioned problems includes a first liquid helium tank that stores liquid helium, a second liquid helium tank that is partitioned from the first liquid helium tank by an adiabatic vacuum, the first liquid helium tank, and the first liquid helium tank. A heat-insulating vacuum container containing two liquid helium tanks, a superconducting magnet installed in the second liquid helium tank, a passage communicating the first liquid helium tank and the second liquid helium tank, A flow rate adjusting valve for adjusting a flow rate of liquid helium passing through the passage, an exhaust pipe for exhausting evaporated helium gas in the second liquid helium tank, and a flow rate of the evaporated helium gas passing through the exhaust pipe. In a superconducting magnet cryostat having an exhaust pipe valve to be adjusted, an exhaust device for exhausting the evaporated helium gas, and a current lead for supplying a current to the superconducting magnet, Position whose serial current lead is introduced into the second liquid helium tank, a feature that is provided at a position lower than the liquid helium surface in said second liquid helium tank is achieved.

本発明によれば、電流リードが飽和超流動ヘリウム槽に導入される位置よりも飽和超流動ヘリウム液面を高くすることが可能となるので、電流リードが飽和蒸気にさらされなくなり、放電の可能性を著しく低減でき、放電を起こすことなく高磁界を発生できる。   According to the present invention, since the liquid surface of the saturated superfluid helium can be made higher than the position where the current lead is introduced into the saturated superfluid helium tank, the current lead is not exposed to saturated vapor and can be discharged. And can generate a high magnetic field without causing discharge.

以下、超電導磁石用クライオスタットにおいて、飽和蒸気圧下の超流動ヘリウムの蒸気中に電流リードがさらされない複数の実施形態について、図面を参照しながら詳細に説明する。   Hereinafter, in a cryostat for a superconducting magnet, a plurality of embodiments in which current leads are not exposed to superfluid helium vapor under saturated vapor pressure will be described in detail with reference to the drawings.

図１は実施例１による超電導磁石用クライオスタットの構成図で、飽和超流動ヘリウムクライオスタットを示している。断熱真空容器１の中に、４．２Ｋの液体ヘリウム２を貯留する第一の液体ヘリウム槽３(常流動ヘリウム槽)と、温度が４．２〜１．５Ｋ程度に保たれる飽和蒸気圧下の液体ヘリウム４を貯留する第二の液体ヘリウム槽５が設置されている。第二の液体ヘリウム槽５内に超電導磁石１４が設けられている。   FIG. 1 is a configuration diagram of a superconducting magnet cryostat according to a first embodiment, and shows a saturated superfluid helium cryostat. The first liquid helium tank 3 (normal flow helium tank) that stores 4.2K liquid helium 2 in the adiabatic vacuum vessel 1 and the saturated vapor pressure at which the temperature is maintained at about 4.2 to 1.5K. A second liquid helium tank 5 for storing the liquid helium 4 is installed. A superconducting magnet 14 is provided in the second liquid helium tank 5.

液体ヘリウム槽３，５は輻射等による熱侵入を低減するために、液体窒素容器６に貯留した液体窒素により７７Ｋ程度まで冷却される７７Ｋシールド７に囲まれている。さらに、第一の液体ヘリウム槽３から第二の液体ヘリウム槽５への輻射等による熱侵入を低減するために４．２Ｋに冷却された４．２Ｋシールド８が第二の液体ヘリウム槽５を囲んでいる。さらに熱侵入を減らすために、液体ヘリウム槽３，５や７７Ｋシールド７に断熱材を巻いていることが好ましい。   The liquid helium tanks 3 and 5 are surrounded by a 77K shield 7 which is cooled to about 77K by liquid nitrogen stored in the liquid nitrogen container 6 in order to reduce heat intrusion due to radiation or the like. Further, a 4.2 K shield 8 cooled to 4.2 K in order to reduce heat intrusion due to radiation or the like from the first liquid helium tank 3 to the second liquid helium tank 5 Surrounding. In order to further reduce heat intrusion, it is preferable that a heat insulating material is wound around the liquid helium tanks 3 and 5 and the 77K shield 7.

第一の液体ヘリウム槽３には、液体ヘリウム２を供給したり、蒸発ガスを放出するための管９を連通させている。第二の液体ヘリウム槽５は排気管１０に連通しており、断熱真空容器１の大気圧側で排気装置１１に接続される。第二の液体ヘリウム槽５内の蒸発ヘリウムガスを排気装置１１で減圧排気することにより、第二の液体ヘリウム槽５及び槽内の液体ヘリウム４の温度が１．５Ｋ程度まで下がる。温度が下がり約２．２Ｋ以下では、第二の液体ヘリウム槽５内の液体ヘリウム４は超流動状態になる。この超流動ヘリウムの圧力は飽和蒸気圧であり、飽和超流動ヘリウムと呼ばれる。   The first liquid helium tank 3 is connected with a pipe 9 for supplying liquid helium 2 and discharging evaporated gas. The second liquid helium tank 5 communicates with the exhaust pipe 10 and is connected to the exhaust device 11 on the atmospheric pressure side of the adiabatic vacuum vessel 1. By evaporating the evaporated helium gas in the second liquid helium tank 5 under reduced pressure by the exhaust device 11, the temperature of the second liquid helium tank 5 and the liquid helium 4 in the tank is lowered to about 1.5K. When the temperature drops and is about 2.2 K or less, the liquid helium 4 in the second liquid helium tank 5 becomes superfluid. The pressure of this superfluid helium is a saturated vapor pressure and is called saturated superfluid helium.

室温部から排気管１０を伝わっての第二の液体ヘリウム槽５への熱侵入を低減するために、排気管１０は７７Ｋシールド７と４．２Ｋシールド８に熱接触させる。排気装置１１としては、飽和超流動ヘリウム１．８Ｋの蒸気圧１．６ｋＰａ程度で大きな排気速度を期待できる油回転ポンプやメカニカルブースターポンプが適当である。排気装置１１の排気量は排気管弁１２で調整する。この弁１２としては、流量調整が可能であり、かつ、弁閉止時のシール性のよいベローズシールバルブが好ましい。   In order to reduce heat intrusion into the second liquid helium tank 5 through the exhaust pipe 10 from the room temperature portion, the exhaust pipe 10 is brought into thermal contact with the 77K shield 7 and the 4.2K shield 8. As the exhaust device 11, an oil rotary pump or a mechanical booster pump that can expect a large exhaust speed with a vapor pressure of about 1.6 kPa of saturated superfluid helium 1.8K is suitable. The exhaust amount of the exhaust device 11 is adjusted by the exhaust pipe valve 12. The valve 12 is preferably a bellows seal valve capable of adjusting the flow rate and having good sealing performance when the valve is closed.

第一の液体ヘリウム槽３から第二の液体ヘリウム槽５への液体ヘリウムの供給は流量調整弁１３を介して行われる。流量調整弁１３は、微流量を調整できるニードル弁が好適である。流量調整弁１３は微流量を調整するので通路が狭く、第一の液体ヘリウム槽３内に混入した空気の固体化したものなどの不純物が弁１３を詰まらせる可能性がある。供給口（取り込み口）に、銅粉をプレスしたものや、あるいは、焼結金属をフィルターとして用いることで詰まりを防ぐことができる。この他、流量調整弁１３の最も狭い隙間のまわりにヒーターを巻き、詰まった場合に加熱してもよい。初期冷却時には大量のヘリウムを第二の液体ヘリウム槽５に供給する必要があるので、微流量調整用弁１３と並列に大流量を流せる弁を設置しておけば好ましい。設置が困難な場合は排気管１０から液体ヘリウムを供給することも可能である。   The liquid helium is supplied from the first liquid helium tank 3 to the second liquid helium tank 5 through the flow rate adjusting valve 13. The flow rate adjustment valve 13 is preferably a needle valve capable of adjusting a fine flow rate. Since the flow rate adjusting valve 13 adjusts the minute flow rate, the passage is narrow, and impurities such as solidified air mixed in the first liquid helium tank 3 may clog the valve 13. Clogging can be prevented by pressing copper powder at the supply port (intake port) or using sintered metal as a filter. In addition, a heater may be wound around the narrowest gap of the flow rate adjusting valve 13 and heated when clogged. Since it is necessary to supply a large amount of helium to the second liquid helium tank 5 during the initial cooling, it is preferable to install a valve capable of flowing a large flow rate in parallel with the fine flow rate adjusting valve 13. When installation is difficult, liquid helium can be supplied from the exhaust pipe 10.

断熱真空容器１外から第二の液体ヘリウム槽５内で冷却される超電導磁石１４へ電流を供給する電流リード１５が断熱真空容器１、第一の液体ヘリウム槽３を貫いて、第二の液体ヘリウム槽５内に設置された超電導磁石１４に接続される。それぞれの槽を電流リード１５が貫く場所は気密を保つ必要があり、特に、第二の液体ヘリウム槽５へ導入される場所は、第二の液体ヘリウム槽５内の液体ヘリウム４が超流動状態となることから、耐スーパーリークとならなければならない。   A current lead 15 for supplying a current from the outside of the adiabatic vacuum vessel 1 to the superconducting magnet 14 cooled in the second liquid helium vessel 5 passes through the adiabatic vacuum vessel 1 and the first liquid helium vessel 3, and the second liquid It is connected to a superconducting magnet 14 installed in the helium tank 5. The place where the current lead 15 penetrates each tank needs to be kept airtight. In particular, the place where the current lead 15 is introduced into the second liquid helium tank 5 is in a state where the liquid helium 4 in the second liquid helium tank 5 is superfluid. Therefore, it must be super leak-proof.

超電導磁石１４としてはＮＭＲ、加速器、核融合炉などに用いる冷却チャネルがない高磁場発生用が適している。   The superconducting magnet 14 is suitable for generating a high magnetic field without a cooling channel used for NMR, an accelerator, a nuclear fusion reactor or the like.

図１に示したように、第二の液体ヘリウム槽５の上部の一部が上方に突出しているために、突出部でない部分から電流リード１５が第二の液体ヘリウム槽５に導入される位置は、第二の液体ヘリウム槽５内の液体ヘリウム液面より下部となることが可能となる。これにより、電流リード１５が超流動ヘリウム４の飽和蒸気にさらされることがなくなり、放電の可能性がなくなる。   As shown in FIG. 1, since a part of the upper portion of the second liquid helium tank 5 protrudes upward, the position where the current lead 15 is introduced into the second liquid helium tank 5 from a portion that is not the protrusion. Can be lower than the liquid helium liquid level in the second liquid helium tank 5. As a result, the current lead 15 is not exposed to the saturated vapor of the superfluid helium 4, and the possibility of discharge is eliminated.

電流リード１５が第二の液体ヘリウム槽５に導入される位置は、超電導磁石１４のクエンチ時に大量の液体ヘリウム４が蒸発してしまうので、第二の液体ヘリウム槽５内にある液面と離れていた方がよい。また、安全への配慮から、第二の液体ヘリウム槽５の突出部にある液面の上方に、第二の液体ヘリウム槽５の容積の１０％以上の容積を持つこととする。   The position where the current lead 15 is introduced into the second liquid helium tank 5 is away from the liquid level in the second liquid helium tank 5 because a large amount of liquid helium 4 evaporates when the superconducting magnet 14 is quenched. It is better to have. For safety reasons, the second liquid helium tank 5 has a volume of 10% or more of the volume of the second liquid helium tank 5 above the liquid surface at the protruding portion of the second liquid helium tank 5.

この場合、超電導磁石１４が液体ヘリウム４から露出しないように液面計１６での監視と液面制御が必要である。液面の高さを制御するには、液面計１６により液面の高さを検知し、液面計モニター１９に液面の高さを表示する。そして、液面の高さが所定の高さに位置するように、排気管弁１２と流量調整弁１３を弁制御装置２０により制御する。所定の高さより液面が下がった時には、流量調整弁１３の開度を大きくし、排気管弁１２の開度を小さくする。逆に所定の位置より液面が上がった場合には、流量調整弁１３の開度を小さくし、排気管弁１２の開度を大きくする。流量調整弁１３や排気管弁１２を電磁弁とすれば遠隔操作が可能となる。   In this case, monitoring with the liquid level gauge 16 and liquid level control are necessary so that the superconducting magnet 14 is not exposed from the liquid helium 4. In order to control the height of the liquid level, the height of the liquid level is detected by the liquid level meter 16 and the height of the liquid level is displayed on the liquid level meter monitor 19. The exhaust pipe valve 12 and the flow rate adjusting valve 13 are controlled by the valve control device 20 so that the liquid level is at a predetermined height. When the liquid level falls below a predetermined height, the opening degree of the flow rate adjustment valve 13 is increased and the opening degree of the exhaust pipe valve 12 is decreased. Conversely, when the liquid level rises from a predetermined position, the opening degree of the flow rate adjustment valve 13 is reduced and the opening degree of the exhaust pipe valve 12 is increased. If the flow rate adjustment valve 13 and the exhaust pipe valve 12 are electromagnetic valves, remote operation is possible.

次に、ヒーターによる温度制御について説明する。飽和超流動ヘリウム槽である第二の液体ヘリウム槽５内には、抵抗温度計１７とヒーター１８が設置されている。第二の液体ヘリウム槽５内の温度は、温度計１７と温度計測器２１により測定される。槽内の温度が所定の温度より低い場合は、温度制御装置２２がヒーター１８を制御することにより、所定の温度まで昇温する。槽内の温度が所定の温度より高い場合は、温度制御装置２２と弁制御装置２０により排気管弁１２の開度が大きくなるように制御し、所定の温度となるように制御する。   Next, temperature control by a heater will be described. A resistance thermometer 17 and a heater 18 are installed in the second liquid helium tank 5 which is a saturated superfluid helium tank. The temperature in the second liquid helium tank 5 is measured by the thermometer 17 and the temperature measuring device 21. When the temperature in the tank is lower than the predetermined temperature, the temperature controller 22 controls the heater 18 to raise the temperature to the predetermined temperature. When the temperature in the tank is higher than a predetermined temperature, the temperature control device 22 and the valve control device 20 are used to control the opening degree of the exhaust pipe valve 12 so as to be a predetermined temperature.

温度制御はこの外にも、特許第２７６０８５８号に記載された圧力の入力による制御の方法などがある。   In addition to this, there is a temperature control method described in Japanese Patent No. 2760858.

図２は実施例２による超電導磁石用クライオスタットの構成図で、制御装置については実施例１と同じになるので省略してある。本実施例では、第二の液体ヘリウム槽５の上部の一部が凹部形状を有し、この凹部の底部から電流リード１５を導入している。その他の点は実施例１と同等の構成である。   FIG. 2 is a block diagram of a cryostat for a superconducting magnet according to the second embodiment, and a control device is omitted because it is the same as that of the first embodiment. In this embodiment, a part of the upper portion of the second liquid helium tank 5 has a concave shape, and the current lead 15 is introduced from the bottom of the concave portion. The other points are the same as those in the first embodiment.

第二の液体ヘリウム槽５の凹部では他の位置よりも液面が低くなり、液面が凹部の内面位置より下がらないので、電流リード１５が超流動ヘリウム４の飽和蒸気にさらされることがなくなり、放電の可能性が著しく低減される。   Since the liquid level is lower in the concave portion of the second liquid helium tank 5 than in other positions and the liquid level does not fall below the inner surface position of the concave portion, the current lead 15 is not exposed to the saturated vapor of the superfluid helium 4. , The possibility of discharge is significantly reduced.

図３は図２の変形例である。断熱真空容器１内の電流リード１５を冷却するためには、断熱真空容器１内（液体ヘリウム槽３，５外）での電流リード１５の長さが短い方がよい。図３では、第二の液体ヘリウム槽５の凹部に対応して第一の液体ヘリウム槽３の下部に凸部を設け、この凸部から電流リード１５を取り出すようにして、電流リード１５の冷却を確保している。   FIG. 3 is a modification of FIG. In order to cool the current lead 15 in the heat insulating vacuum vessel 1, it is preferable that the length of the current lead 15 in the heat insulating vacuum vessel 1 (outside the liquid helium tanks 3 and 5) is short. In FIG. 3, a convex portion is provided in the lower portion of the first liquid helium tank 3 corresponding to the concave portion of the second liquid helium tank 5, and the current lead 15 is taken out from the convex portion to cool the current lead 15. Is secured.

図４は実施例３による超電導磁石用クライオスタットの構成図である。図示したように第二の液体ヘリウム槽５に突出部がなく、第一の液体ヘリウム槽３の下部に下方への突出部を設け、この突出部を経て電流リード１５が第二の液体ヘリウム槽５へ導入される。その他の点は実施例１と同等の構成である。   FIG. 4 is a configuration diagram of a cryostat for a superconducting magnet according to a third embodiment. As shown in the drawing, the second liquid helium tank 5 has no protrusion, and a downward protrusion is provided at the lower part of the first liquid helium tank 3, and the current lead 15 passes through the protrusion to the second liquid helium tank 5. 5 is introduced. The other points are the same as those in the first embodiment.

電流リード１５の導入位置が第二の液体ヘリウム槽５の液面よりも低くなるように液面を設定するので、放電の可能性がなくなる。この場合、超電導磁石１４が液体ヘリウム４から露出しないように液面計１６での監視と液面制御が必要である。   Since the liquid level is set so that the introduction position of the current lead 15 is lower than the liquid level of the second liquid helium tank 5, the possibility of discharge is eliminated. In this case, monitoring with the liquid level gauge 16 and liquid level control are necessary so that the superconducting magnet 14 is not exposed from the liquid helium 4.

以上のように、本発明の複数の実施例を示したが、本発明の超電導磁石用クライオスタットは高磁場が必要な高感度ＮＭＲ、ＭＲＩ用超電導磁石の冷却システムに利用できる。   As described above, a plurality of embodiments of the present invention have been shown. However, the cryostat for a superconducting magnet according to the present invention can be used for a cooling system for high-sensitivity NMR and MRI superconducting magnets requiring a high magnetic field.

本発明の実施例１による超電導磁石用クライオスタットの構成図。The block diagram of the cryostat for superconducting magnets by Example 1 of this invention. 実施例２による超電導磁石用クライオスタットの構成図。The block diagram of the cryostat for superconducting magnets by Example 2. FIG. 実施例２の変形例による超電導磁石用クライオスタットの構成図。The block diagram of the cryostat for superconducting magnets by the modification of Example 2. FIG. 実施例３による超電導磁石用クライオスタットの構成図。FIG. 6 is a configuration diagram of a cryostat for a superconducting magnet according to a third embodiment.

符号の説明Explanation of symbols

１…断熱真空容器、２…４．２Ｋ液体ヘリウム、３…第一の液体ヘリウム槽（４．２Ｋ）、４…液体ヘリウム（１．５〜４．２Ｋ）、５…第二の液体ヘリウム槽（１．５〜４．２Ｋ）、６…液体窒素容器、７…７７Ｋシールド、８…４．２Ｋシールド、９…４．２Ｋ液体ヘリウム供給管及び蒸気放出管、１０…排気管、１１…排気装置、１２…排気管弁、１３…流量調整弁、１４…超電導磁石、１５…電流リード、１６…液面計、１７…温度計、１８…ヒーター、１９…液面モニタ、２０…弁制御装置、２１…温度計測器、２２…温度制御装置。   DESCRIPTION OF SYMBOLS 1 ... Adiabatic vacuum vessel, 2 ... 4.2K liquid helium, 3 ... 1st liquid helium tank (4.2K), 4 ... Liquid helium (1.5-4.2K), 5 ... 2nd liquid helium tank (1.5-4.2K), 6 ... liquid nitrogen container, 7 ... 77K shield, 8 ... 4.2K shield, 9 ... 4.2K liquid helium supply pipe and vapor discharge pipe, 10 ... exhaust pipe, 11 ... exhaust Device: 12 ... Exhaust pipe valve, 13 ... Flow control valve, 14 ... Superconducting magnet, 15 ... Current lead, 16 ... Liquid level gauge, 17 ... Thermometer, 18 ... Heater, 19 ... Liquid level monitor, 20 ... Valve control device , 21 ... temperature measuring device, 22 ... temperature controller.

Claims (10)

液体ヘリウムを貯留する第一の液体ヘリウム槽と、前記第一の液体ヘリウム槽と断熱真空により仕切られる第二の液体ヘリウム槽と、前記第一の液体ヘリウム槽と前記第二の液体ヘリウム槽を内包する断熱真空容器と、前記第二の液体ヘリウム槽内に設置される超電導磁石と、前記第一の液体ヘリウム槽と前記第二の液体ヘリウム槽とを連通する通路と、前記通路を通過する液体ヘリウムの流量を調節する流量調整弁と、前記第二の液体ヘリウム槽内の蒸発ヘリウムガスを排気する排気管と、前記排気管を通過する前記蒸発ヘリウムガスの流量を調節する排気管弁と、前記蒸発ヘリウムガスを排気する排気装置と、前記超電導磁石に電流を供給するための電流リードと、を有する超電導磁石用クライオスタットにおいて、
前記電流リードが前記第二の液体ヘリウム槽に導入される位置は、前記第二の液体ヘリウム槽内にある液体ヘリウム液面よりも低い位置に設けられることを特徴とする超電導磁石用クライオスタット。 A first liquid helium tank for storing liquid helium; a second liquid helium tank partitioned from the first liquid helium tank by an adiabatic vacuum; the first liquid helium tank; and the second liquid helium tank. A heat insulating vacuum vessel to be included, a superconducting magnet installed in the second liquid helium tank, a passage communicating the first liquid helium tank and the second liquid helium tank, and the passage. A flow rate adjusting valve for adjusting the flow rate of liquid helium, an exhaust pipe for exhausting the evaporated helium gas in the second liquid helium tank, and an exhaust pipe valve for adjusting the flow rate of the evaporated helium gas passing through the exhaust pipe; A superconducting magnet cryostat having an exhaust device for exhausting the evaporated helium gas and a current lead for supplying a current to the superconducting magnet.
A superconducting magnet cryostat, wherein the current lead is introduced into the second liquid helium tank at a position lower than the liquid helium liquid level in the second liquid helium tank. 前記第二の液体ヘリウム槽の一部分が上方に突出している突出部を有し、前記電流リードが導入される位置は前記突出部以外の前記第二の液体ヘリウム槽の上部であることを特徴とする請求項１記載の超電導磁石用クライオスタット。   A part of the second liquid helium tank has a protruding part protruding upward, and the position where the current lead is introduced is an upper part of the second liquid helium tank other than the protruding part. The cryostat for a superconducting magnet according to claim 1. 前記第二の液体ヘリウム槽の突出部に液体ヘリウムの液面の位置を測定する液面計を有することを特徴とする請求項２記載の超電導磁石用クライオスタット。   The cryostat for a superconducting magnet according to claim 2, further comprising a liquid level gauge for measuring the position of the liquid level of the liquid helium at the protruding portion of the second liquid helium tank. 前記流量調整弁と前記排気管弁とによって、前記第二の液体ヘリウム槽の突出部に液体ヘリウムの液面が位置するように制御することを特徴とする請求項１記載の超電導磁石用クライオスタット。   2. The cryostat for a superconducting magnet according to claim 1, wherein the liquid level of liquid helium is controlled by the flow rate adjusting valve and the exhaust pipe valve so that a liquid surface of the liquid helium is positioned at a protruding portion of the second liquid helium tank. 前記第二の液体ヘリウム槽の突出部にある液体ヘリウムの液面より上方の突出部の空間の容積が、前記第二の液体ヘリウム槽の容積の１０％以上であることを特徴とする請求項１記載の超電導磁石用クライオスタット。   The volume of the space of the protrusion above the liquid level of liquid helium in the protrusion of the second liquid helium tank is 10% or more of the volume of the second liquid helium tank. A cryostat for a superconducting magnet according to 1. 前記第二の液体ヘリウム槽の上部の一部分が凹形状を有し、前記電流リードが導入される位置は前記凹形状の部分であり、前記第二の液体ヘリウム槽内にある液体ヘリウム液面よりも低いことを特徴とする請求項１記載の超電導磁石用クライオスタット。   A part of the upper part of the second liquid helium tank has a concave shape, and the position where the current lead is introduced is the concave part, from the liquid helium level in the second liquid helium tank The cryostat for a superconducting magnet according to claim 1, wherein the cryostat is also low. 前記流量調整弁と前記排気管弁とによって、前記第二の液体ヘリウム槽の前記凹形状部分よりも高い位置に液体ヘリウムの液面が位置するように制御することを特徴とする請求項６記載の超電導磁石用クライオスタット。   The liquid flow rate of the liquid helium is controlled to be higher than the concave portion of the second liquid helium tank by the flow rate adjusting valve and the exhaust pipe valve. Cryostat for superconducting magnet. 前記第二の液体ヘリウム槽内にある液体ヘリウムの液面より上方の空間の容積が、前記第二の液体ヘリウム槽の容積の１０％以上であることを特徴とする請求項６記載の超電導磁石用クライオスタット。   The superconducting magnet according to claim 6, wherein the volume of the space above the liquid level of the liquid helium in the second liquid helium tank is 10% or more of the volume of the second liquid helium tank. For cryostat. 前記第一の液体ヘリウム槽の底部の一部分が下方に突出している突出部を有し、前記突出部の下端は前記第二の液体ヘリウム槽の液体ヘリウムの液面より低い位置にあり、前記電流リードが前記第二の液体ヘリウム槽に導入される位置は、前記突出部を経て前記第二の液体ヘリウム槽内にある液体ヘリウム液面よりも低いことを特徴とする請求項１記載の超電導磁石用クライオスタット。   A portion of the bottom of the first liquid helium tank has a protrusion protruding downward, and the lower end of the protrusion is at a position lower than the liquid helium level of the second liquid helium tank, and the current 2. The superconducting magnet according to claim 1, wherein a position where the lead is introduced into the second liquid helium tank is lower than a liquid helium liquid level in the second liquid helium tank through the protruding portion. For cryostat. 前記流量調整弁と前記排気管弁とによって、前記第二の液体ヘリウム槽に前記電流リードが導入される位置よりも高い位置に液体ヘリウム液面が位置するように制御することを特徴とする請求項９記載の超電導磁石用クライオスタット。   The liquid helium liquid level is controlled to be positioned higher than the position where the current lead is introduced into the second liquid helium tank by the flow rate adjusting valve and the exhaust pipe valve. Item 10. A cryostat for a superconducting magnet according to Item 9.
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