JP3569997B2 - Current leads for superconducting devices - Google Patents

Current leads for superconducting devices Download PDF

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JP3569997B2
JP3569997B2 JP07112095A JP7112095A JP3569997B2 JP 3569997 B2 JP3569997 B2 JP 3569997B2 JP 07112095 A JP07112095 A JP 07112095A JP 7112095 A JP7112095 A JP 7112095A JP 3569997 B2 JP3569997 B2 JP 3569997B2
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lead
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JPH08321416A (en
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敬昭 坊野
雅行 今野
喜善 榊
清 滝田
保川　　幸雄
郁夫 伊藤
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Fuji Electric Co Ltd
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Fuji Electric Systems Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
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Description

【０００１】
【産業上の利用分野】
この発明は、極低温にある超電導コイルに室温にある電源から電流を通流する超電導装置用電流リード、とくに、低温側に高温酸化物超電導体を用いた超電導装置用電流リードに関する。
【０００２】
【従来の技術】
超電導コイルは、液体ヘリウム等の極低温冷媒によって冷却して使用することが必要であり、通常、液体窒素シールドや高真空層で熱の侵入を阻止した真空断熱容器内に設けられた液体ヘリウム容器に液体ヘリウムに浸漬した状態で収納される。電流リードは、極低温に保持された超電導コイルに室温部にある電源から励磁電流を通流するために設けられるものであり、通電に伴うジュール発熱、および常温側から極低温側へ熱伝導により侵入する熱を抑えて液体ヘリウムの蒸発量を低減するために、電流リードの内部に気化した低温のヘリウムガスを流して冷却し、除熱するように構成するのが通例である。電流リードの導体としては、銅または銅合金等の良導電性金属が一般的に用いられるが、断面積を大きくしてジュール発熱を抑えると熱伝導による侵入熱量が増大し、断面積を小さくして熱伝導による侵入熱量を抑えるとジュール発熱が増大するので、低減できる液体ヘリウムの蒸発量には限界がある。これに対し、高温酸化物超電導体を低温側リードの導体に配し、良導電性金属を導体とする高温側リードと直列に接続して構成した超電導装置用電流リード（例えば、特開昭63−292610号公報参照）が液体ヘリウムの蒸発量を飛躍的に低減するものとして注目されている。
【０００３】
図１４は、従来の超電導装置用電流リードを組み込んだ超電導装置を模式的に示した断面図である。超電導コイル１は、真空断熱容器４の液体ヘリウム容器２に液体ヘリウム３に浸漬した状態で収納され、超電導状態に保持される。電流リード１１は、銅または銅合金等の良導電性金属導体からなる高温側リード１３と、高温酸化物超電導導体からなる低温側リード１２とが中間接続部１４で導電接続された直列接続体からなり、低温端子３２が超電導コイル１に連結された低温側接続導体５に接続され、常温端子３３が図示しない電源に接続されることにより、超電導コイル１に電流が供給される。また、電流リード１１は、液体ヘリウム容器２で蒸発し気化した低温のヘリウムガス３Ｇを、低温側リード１２の下端より導入して冷却される。
【０００４】
低温側リード１２の高温酸化物超電導導体として、イットリウム系やビスマス系等のセラミックス系高温超電導体を用いれば、おおよそ液体窒素温度以下で超電導状態となるのでジュール発熱がゼロになり、また、これらの熱伝導率は銅の場合に比べて２〜３桁も小さいので伝導による侵入熱も大幅に低減される。低温側リード１２の導体として適用する場合の形状としては、高温超電導材粉末を圧縮成形し熱処理したバルク型高温酸化物超電導体と、銀あるいはその合金等をシース材として圧縮成形し熱処理したシース型高温酸化物超電導体が知られている。このうちシース型高温酸化物超電導体は、バルク型高温酸化物超電導体よりも臨界電流密度が数十倍も大きく、コンパクト化には有利であるが、シース材として使用している銀あるいはその合金等の熱伝導率が大きいので、高温酸化物超電導体の低熱伝導率という特徴を生かすことができない。したがって、低温側リード１２の導体としてはバルク型高温酸化物超電導体が用いられるのが一般的である。
【０００５】
【発明が解決しようとする課題】
上記のように構成した電流リードでは、低温側リードでのジュール発熱が皆無となり、かつ熱伝導率が極めて小さく伝導による侵入熱も微小となるので、電流リードによる液体ヘリウムの蒸発を微量に抑制でき、超電導装置を極めて効率的なものとすることができる。
【０００６】
しかしながら、このように構成された電流リードにおいても、接続した超電導コイルに通電しているとき、何らかの原因によって低温側リードの高温酸化物超電導導体が超電導状態から常電導状態へ転移すると、常電導状態での電気抵抗は金属の１００倍以上と高いので、多大なジュール発熱を生じて導体の温度が上昇し、通電電流を瞬時に減衰させないと焼損してしまう危険性がある。
【０００７】
一方、一般的な超電導装置では、図１５に励磁回路の基本構成図を示したように、超電導コイル２１を一対の電流リード２２および２２Ａを介して電源２３に接続し励磁する回路において、超電導コイル２１に並列に保護抵抗２４が組み込まれている。超電導コイル２１が何らかの原因によって超電導状態から常電導状態への転移を生じた場合、スイッチ２５を遮断して超電導コイル２１と保護抵抗２４からなる閉回路を形成させ、励磁された超電導コイル２１に蓄積された多大な磁気エネルギーを真空断熱容器２６の外部の室温部分に配置した保護抵抗２４に取り出すことにより、超電導コイル２１および真空断熱容器２６の損傷を防止している。
【０００８】
したがって、上記のように電流リードの低温側リードの高温酸化物超電導導体が超電導状態から常電導状態へ転移したとき、これを検知してスイッチ２５を遮断しても、超電導コイル２１を流れる電流すなわち電流リードを流れる電流は超電導コイル２１のインダクタンスと保護抵抗２４の抵抗値で定まる時定数で減衰することとなり、電流リードの保護を念頭にした瞬時の減衰を行うことはできない。このため高温酸化物超電導導体の温度が急激に上昇し、焼損する可能性が高くなる。電流リードが焼損すると、図１５に示した超電導コイル２１と保護抵抗２４からなる閉回路が、電流リード２２または２２Ａにおいて開放された状態となるので、超電導コイル２１に蓄積されたエネルギーを保護抵抗２４に取り出すことが不可能となり、絶縁破壊等の超電導コイル２１の損傷や、電源２３や真空断熱容器２６に損傷を生じる危険性が高くなる。
【０００９】
この発明は、上記の問題点に鑑みてなされたものであり、その目的は、良導電性金属を導体とする高温側リードと、高温酸化物超電導体を導体とする低温側リードの直列接続体で構成された超電導装置用電流リードにおいて、通電時に高温酸化物超電導体が何らかの原因により常電導状態へ転移することがあっても、異常温度上昇による焼損が防止され、超電導コイル、電源、あるいは断熱真空容器に損傷を生ずることなく、安全に使用できる超電導装置用電流リードを提供することにある。
【００１０】
【課題を解決するための手段】
上記目的を達成するために、この発明においては、
(1) 真空断熱容器の液体ヘリウム容器内に液体ヘリウムに浸漬した状態で収納された超電導コイルに外部電源より電流を通流する超電導装置用電流リードで、良導電性金属を導体とする高温側リードと、高温酸化物超電導体を導体とする低温側リードの直列接続体で構成され、ヘリウムガスを通流して高温酸化物超電導体を超電導状態として用いるものにおいて、低温側リードに並列に電気接続された保護導体を配設するとともに、この保護導体を、例えばブロンズ、ベリリウム銅合金、またはニッケル銅合金等からなる複数の導電性金属導体の線束から形成し、低温側リードを冷却するヘリウムガスの流通路に稠密に配することとし、低温側リードを筒状に形成し、その内面に接する空間に保護導体を稠密に配することとし、さらには、低温側リードを筒状に形成するとともに低温側リードの内部の横断面での中心部に気密な部材よりなる封止部材を配して、この封止部材と低温側リードの内面との間に、低温側リードを冷却するヘリウムガスの流通路となる空間を形成し、この空間に保護導体を稠密に配することとする。
【００１１】
(2) さらに、上記の線束を形成する導電性金属導体の、少なくとも一部の、内部に金属系超電導体、または化合物系超電導体を埋め込むこととする。
(3) また、上記の超電導装置用電流リードに、前記超電導コイルに通流する電流容量をもち良導電性金属を導体とする補助電流リードを付設し、かつこれらの電流リードの低温端子を超電導コイルに連結した低温側接続導体に電気接続することとする。
【００１２】
(4) さらに、上記のごとく超電導装置用電流リードに付設した補助電流リードを、室温部での操作により低温端子部で着脱可能に構成することとする。
【００１３】
【作用】
超電導装置用電流リードを上記(1) のように、保護導体を低温側リードに並列に電気接続して配設させるものとすれば、低温側リードの高温酸化物超電導導体が常電導転移を生じても、高温酸化物超電導導体を流れていた電流は並列接続された保護導体にバイパスされるので、超電導コイルに蓄積されていた磁気エネルギーは外部に設置された保護抵抗で確実に消費されることとなる。したがって、本構成とすれば、超電導コイルや真空断熱容器等の損傷を生じることなく安全に使用できる超電導装置用電流リードとすることができる。
【００１４】
また、保護導体を、例えばブロンズ、ベリリウム銅合金、またはニッケル銅合金等からなる複数の導電性金属導体の線束から形成し、低温側リードを冷却するヘリウムガスの流通路に稠密に配することとし、例えば、低温側リードを筒状に形成しその内面に接する空間に保護導体を稠密に配することとすれば、多数の線束から形成されることによって、保護導体の断面積当たりの表面積が大きくなり、ヘリウムガスの流通路に稠密に配置されることによって均一、かつ効率的に冷却されることとなる。したがって、定常運転時の熱侵入量が少量に抑えられ、また、高温酸化物超電導導体が常電導転移を生じた際には効果的に電流をバイパスさせることができることとなる。
【００１５】
さらに、上記(2) のように、保護導体の線束を形成する導電性金属導体の、少なくとも一部の導体の内部に金属系超電導体、または化合物系超電導体を埋め込むこととすれば、埋め込まれた超電導体の臨界温度以下の部分では保護導体も超電導状態となる。したがって、長時間の使用に伴い、例えば熱サイクルによるクラックの発生等により、低温側リードを構成する高温酸化物超電導体が破損して通電が不能となる事態が生じても、低温側リードの補修を行わずとも保護導体を介して定常運転を持続させることができ、かつ侵入熱の増大を抑制することができることとなる。
【００１６】
また、上記(3)のように、これらの電流リードに、良導電性金属を導体とする補助電流リードを付設し、それぞれの低温端子を超電導コイルに連結された低温側接続導体に電気接続することとすれば、高温酸化物超電導導体が焼損し使用不能となったとき、電源と連結する常温側の接続導体を、破損した電流リードの常温端子から補助電流リードの常温端子につなぎかえることにより、容易に超電導コイルの再励磁を可能とすることができる。
【００１７】
さらに、上記(4)のように、付設した補助電流リードを低温端子部で着脱可能な電流リードとすれば、保護導体を配設した低温側リードを用いての通常の通電操作のときには、付設した補助電流リードを取り外して使用できるので、補助電流リードでの熱伝導による侵入熱量を皆無とすることができる。また、高温酸化物超電導導体が焼損し使用不能となったときには、補助電流リードを装着し、常温側の接続導体をつなぎかえることにより、超電導コイルの再励磁を可能とすることができる。
【００１８】
【実施例】
以下、この発明の実施例および参考例を図面にもとづいて説明する。
図１は、この発明の第１の参考例による超電導装置用電流リードを組み込んだ超電導装置の模式的な縦断面図である。すでに説明した従来例と同一機能を有する構成部品については同一符号を付して、重複した説明は省略する。
【００１９】
この図において、ステンレス鋼材等の金属材料で形成された保護導体１５は、低温側リード１２に並列に電気接続されて配設されている。低温側リード１２を構成する高温酸化物超電導導体は、正常運転の超電導状態では電気抵抗がゼロであるので、電流リード１１Ａを流れる電流は高温酸化物超電導導体を流れ、保護導体１５には流れないが、高温酸化物超電導導体が常電導状態に転移すると、高温酸化物超電導導体はセラミックスであり絶縁体に近い極めて高い電気抵抗率を呈するので、電流リード１１Ａを流れる電流は保護導体１５にバイパスすることとなる。したがって、高温酸化物超電導導体の常電導状態への転移とともに、すでに図１５に示したように、スイッチ２５を遮断することにより超電導コイル２１を電源２３から切り離し、超電導コイル２１に貯えられた磁気エネルギーを保護抵抗２４に取り出すこととすれば、この間低温側リード１２を流れる電流はほぼゼロであるので、過大な温度上昇を生ずることなく安全に装置を停止することができる。なお、仮に低温側リード１２が破損したとしても、磁気エネルギーは保護導体を介して保護抵抗に取り出されるので、超電導コイル、電源、あるいは真空断熱容器を損傷することなく、装置を安全に停止することができる。
【００２０】
保護導体１５は、上記のごとく、超電導装置を構成する超電導コイル２１の保護方式に係わるものであり、その材料、寸法等は、超電導コイル２１の最大蓄積エネルギーや保護抵抗２４の抵抗値、低温側リード１２の正常時の許容侵入熱量、あるいは保護導体１５の許容最高温度等により決められるものである。例えば、銅あるいはその合金、アルミニウムあるいはその合金等は電気抵抗率が小さく通電電流密度が高くとれるので、保護導体１５としての寸法は小さくてすむが、これらは熱伝導率が高いので、正常時の侵入熱量が過大となるおそれがある。その点でステンレス鋼材を用いれば侵入熱量を抑制する点で有効であるが、通電時の温度上昇が過大とならないように配慮する必要がある。
【００２１】
なお、保護導体１５を筒状に形成し、低温端子３２に設けられた図示しない通流溝を通じて保護導体１５の内部へ低温のヘリウムガスを導き、中間接続部１４に設けられた図示しない通流溝を通じて高温側リード１３へと流すこととすれば、低温側リード１２を構成する高温酸化物超電導導体、さらには保護導体１５が効果的に冷却され、定常運転時の侵入熱量が効果的に低減される。
【００２２】
図２は、この発明の第２の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な縦断面図である。本参考例の第１の参考例との相違点は、ステンレス鋼材で形成された保護導体１５が電気接続部に良導電性金属からなる金属膜１７Ａおよび１７Ｂを備えている点にあり、金属膜１７Ａを良導電性金属からなる中間接続体１４に、また金属膜１７Ｂを良導電性金属からなる低温端子３２にハンダ接続することにより、高温酸化物超電導導体からなる低温側リード１２と並列接続となるよう電気接続されている。ステンレス鋼材で形成された保護導体１５を中間接続体１４および低温端子３２へ直接電気接続するには、ハンダ接続は極めて困難であるので、溶接接続を行うことが必要となる。しかしながら、溶接接続を行うと周囲温度が高温となるので、低温側リード１２を構成する高温酸化物超電導導体が組成変化を起こして超電導特性が大幅に低下してしまう可能性が極めて高い。これに対して、本参考例のように、電気接続部に良導電性金属からなる金属膜１７Ａおよび１７Ｂを予め備えた保護導体１５を用いてハンダ接続することとすれば、高温酸化物超電導導体の特性を損なうことなく接続抵抗を微小に抑えて接続することができる。なお、ステンレス鋼材等の金属材料からなる保護導体１５の電気接続部へ良導電性金属からなる金属膜１７Ａおよび１７Ｂを形成する方法としては、めっき処理法、蒸着法、スパッタリング法あるいは溶射法等が用いられる。
【００２３】
図３は、この発明の第３の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な縦断面図である。本参考例の特徴は、保護導体１５Ａが、電気接続部となる両端部に銅あるいは銅合金等からなる良導電性金属１８Ａおよび１８Ｂを配し、中央部にステンレス鋼材等からなる低熱伝導性金属１９を配して接合した直列接続体からなることにある。この構成では、電気接続部に良導電性金属１８Ａおよび１８Ｂが用いられているので、第２の参考例と同様に、中間接続体１４および低温端子３２とハンダ接続により容易に電気接続することができ、かつ中央部に低熱伝導性金属１９を配しているので、保護導体１５Ａを介して低温部へ侵入する熱量を効果的に抑制することができる。なお、良導電性金属１８Ａおよび１８Ｂと低熱伝導性金属１９との異種金属間の接合は、摩擦圧接法や電気圧着法により比較的容易に行うことができる。
【００２４】
図４は、この発明の第４の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な縦断面図である。本参考例の特徴は、保護導体１５Ｂが、ベローズ状に形成された可撓性を保持したステンレス鋼材よりなることである。電流リードを超電導装置に組み込んで使用する際には、電流リードの各部は低温のヘリウムガスにより冷却されるので、構成材料の熱膨張係数ならびに冷却される温度に対応して熱収縮する。低温側リード１２と保護導体１５Ｂの間においても、構成材料の差によって熱収縮量の差が生じて互いに熱応力を及ぼすこととなり、熱応力が過大になると強度の劣る高温酸化物超電導導体からなる低温側リード１２が破損する恐れがある。本参考例の構成においては、保護導体１５Ｂが可撓性を保持するように構成されているので、熱収縮量に差が生じても熱応力が緩和され、上記のごとき低温側リード１２の破損は回避することができる。また、保護導体１５Ｂをベローズ状に形成したことにより、保護導体１５Ｂを介しての熱伝導による熱侵入量がより低減するという効果も得られる。なお、本構成ではステンレス鋼材よりなる保護導体１５Ｂが可撓性を保持したものを例示したが、保護導体１５Ｂが良導電性金属からなるもの、あるいは第３の参考例に示したごとく良導電性金属と低熱伝導性金属を接合した直列接続体からなるものであっても、可撓性を保持した構成とすれば同様な効果が得られることは例示するまでもない。
【００２５】
図５は、この発明の第５の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図で、（ａ）は全体断面図、（ｂ）は（ａ）に用いられる低温側リードの断面図、（ｃ）は（ａ）に用いられる他の低温側リードの断面図である。本参考例においては、（ｂ）に示したようにステンレス鋼製の丸棒状の保護導体１５Ｃ、あるいは（ｃ）に示したようにステンレス鋼製の円筒状の保護導体１５Ｄを埋設した、複数の高温酸化物超電導導体からなる低温側リード１２Ａが、中空管２０の内部に配設され、導入されるヘリウムガスにより冷却されて超電導状態に保持される。本構成においては、保護導体１５Ｃあるいは１５Ｄと低温側リード１２Ａが上端部、下端部のみならず長手方向の全長にわたって電気的に連結されるので、並列接続体として効果的であり、さらに一体に形成されているので、本質的に脆い高温酸化物超電導導体の機械的強度がステンレス鋼製の保護導体１５Ｃあるいは１５Ｄによって補強され、低温側リード１２Ａの機械的損傷が防止される。また、（ｃ）に示した円筒状の保護導体１５Ｄを埋設した低温側リード１２Ａは、外周を流れるヘリウムガスと保護導体１５Ｄの内部を流れるヘリウムガスとにより効果的に冷却されることとなる。
【００２６】
図６は、この発明の第６の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図である。本参考例においては、複数の丸棒状のバルク型の高温酸化物超電導導体からなる低温側リード１２Ｂと、複数のステンレス鋼製の丸棒状の保護導体１５Ｅが、中空管２０Ａの内部に稠密に配設され、長手方向の両端部で電気的、機械的に接続されており、中空管２０Ａの内部の空隙を流れるヘリウムガスにより冷却して超電導状態に保持して使用される。
【００２７】
図７は、この発明の第７の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図である。本参考例の第６の参考例との差は、複数の丸棒状のバルク型の高温酸化物超電導導体からなる低温側リード１２Ｂに代わって、複数の丸棒状のシース型の高温酸化物超電導導体からなる低温側リード１２Ｃが使用されている点にあり、その他は同一である。
【００２８】
上記の第６の参考例および第７の参考例による超電導装置用電流リードにおいては、中空管２０Ａの内部に占める低温側リード１２Ｂ（あるいは１２Ｃ）と保護導体１５Ｅの全断面積の割合が５０％以上に選定されており、導入されるヘリウムガスは均一に分散配置された低温側リード１２Ｂ（あるいは１２Ｃ）と保護導体１５Ｅの空隙にほぼ均一に分布して流れることとなる。したがってヘリウムガスの流量が少量でも流速が高まり、熱伝達率が向上して、効果的に冷却されることとなる。
【００２９】
図８は、この発明の第１の実施例による超電導装置用電流リードの低温側部分の基本構成を拡大して示す模式断面図で、（ａ）は縦断面図、（ｂ）は要部の横断面図である。本構成においては、（ａ）に見られるように、円筒状に形成された低温側リード１２Ｄは高温側を中間接続部１４Ａに、また低温側を低温端子３２Ｂに嵌合され半田付け接続されている。低温側リード１２Ｄの内部の中心部には気密な部材で形成された封止部材４３が配され、封止部材４３と低温側リード１２Ｄの内面との間の空間に多数本のニッケル銅合金からなる保護導体１５Ｆが組み込まれている。保護導体１５Ｆの一端は、高温側接続体４１を介して中間接続部１４Ａに、また他端は、低温側接続体４２を介して低温端子３２Ｂに導電接続されており、保護導体１５Ｆと低温側リード１２Ｄは電気的に並列接続体を構成している。また（ｂ）に見られるように、多数本のニッケル銅合金からなる保護導体１５Ｆは、封止部材４３と低温側リード１２Ｄの内面との間の空間に稠密に挿入、配置されており、（ａ）に図示したごとく低温端子３２Ｂに設けられた通流孔を通して導入され、中間接続部１４Ａに設けられた通流孔を通して高温側リードへと送られるヘリウムガス３Ｇにより冷却され、侵入熱が除去される。本構成では、封止部材４３と低温側リード１２Ｄの内面との間の空間の横断面に占める保護導体１５Ｆの断面積の割合が７０％以上に達しており、ヘリウムガス３Ｇが各部で均一に流れるので、保護導体１５Ｆおよび低温側リード１２Ｄが均一に冷却され、これらを介して低温端子３２Ｂに侵入する伝導熱が低減されることとなる。
【００３０】
図９は、この発明の第８の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図である。本実施例においては、多数本のニッケル銅合金からなる保護導体１５Ｆが、円柱状に形成された低温側リード１２Ｅと外周部のカバー４４との間の空間に稠密に挿入、配置されている。本構成においても、第１の実施例と同様に、低温側リード１２Ｅに並列接続された保護導体１５Ｆがヘリウムガスにより効果的に冷却され、侵入熱が低減されることとなる。また本構成では、低温側リード１２Ｅの外周部に保護導体１５Ｆを配置したのちカバー４４を任意に形成することができるので、保護導体１５Ｆを稠密に挿入、配置するのが容易となる利点がある。
【００３１】
図１０は、この発明の第２の実施例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図である。本実施例では、前述の第１の実施例と同様に、円筒状の低温側リード１２Ｄの内部の封止部材４３との間隙に保護導体１５Ｇを配して構成されている。本実施例の第１の実施例との差異は、保護導体１５Ｇの構成にあり、第１の実施例においては多数本のニッケル銅合金が用いられているのに対して、本実施例では、金属系超電導体の Nb-Ti合金の細線が埋め込まれた多数本のニッケル銅合金が用いられている点にある。本構成では、低温状態において Nb-Ti合金が超電導状態となるので、仮に低温側リード１２Ｄを構成する高温酸化物超電導体が劣化して通電不能となる事態となっても、低温側リード１２Ｄを補修することなく、本保護導体１５Ｇを介して定常的な通電を継続できるという利点がある。
【００３２】
なお、本実施例において、多数本のニッケル銅合金に金属系超電導体の Nb-Ti合金が埋め込まれたものを例示したが、 Nb-Ti合金は多数本のニッケル銅合金のすべてに埋め込まれている必要はなく、通電電流容量に見合って一部のニッケル銅合金にのみ埋め込まれていても同等の効果が得られる。また埋め込まれる超電導体は Nb-Ti合金に限るものではなく、Nb-Ti-Ta 合金等の金属系超電導体や、 Nb3Sn、 Nb3Al等の化合物系超電導体を用いることとしても、その超電導体の臨界温度、通電容量に対応して、同様の効果が得られることとなる。
【００３３】
図１１は、この発明の第９の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図である。本実施例では、二重円筒状に形成された低温側リード１２Ｆの間隙および最内部に、多数本のニッケル銅合金からなる保護導体１５Ｆを稠密に配して構成されている。本構成では、低温側リード１２Ｆおよび保護導体１５Ｆの断面積を相対的に大きく採ることができるので、通電電流容量の大きな超電導装置用電流リード用として効果的である。
【００３４】
なお、上述の図８〜図１１に示した第１〜第２の実施例および第８〜第９の参考例においては、保護導体として多数本のニッケル銅合金を用いることとしているが、ニッケル銅合金に限るものではなく、例えばブロンズ、ベリリウム銅合金等の導電性金属導体であれば、同等の効果が得られることは例示するまでもない。
図１２は、この発明の第３の実施例による超電導装置用電流リードを組み込んだ超電導装置の模式的な縦断面図である。高温側リード１３と低温側リード１２からなり、保護導体１５を低温側リード１２と電気的に並列に接続した電流リード１１Ａに、良導電性金属を導体とする補助電流リード１６が付設されており、それぞれの低温端子が超電導コイル１に連結された低温側接続導体５Ａに電気接続されている。この構成においては、低温側リード１２を構成する高温酸化物超電導導体が焼損し使用不能となったとき、電源と連結する常温側の接続導体を、破損した電流リード１１Ａの常温端子３３から補助電流リード１６の常温端子３３Ａにつなぎかえることにより、超電導コイルの再励磁が可能となる。低温側リード１２を構成する高温酸化物超電導導体が焼損し使用不能となり、これを交換するには、極低温の雰囲気下にある低温端子３２での分離、つなぎ換えが必要となり、そのためには、装置の冷却を停止し、温度を上げて低温端子３２を室温とする必要があり、極めて不経済であるが、補助電流リード１６を付設しておけば、常温側の接続導体を付け替えるだけで容易に再励磁することができる。
【００３５】
なお、補助電流リード１６を付設したことにより、電流リード１１Ａが正常に運転されている際にも、補助電流リード１６を介して熱伝導により極低温部に熱が侵入するが、この際には電流は流れていないので、ジュール発熱はなく、熱伝導による微小分を除去するように、少量の低温ヘリウムガスを流して冷却すればよい。
【００３６】
図１３は、この発明の第４の実施例による超電導装置用電流リードを組み込んだ超電導装置の模式的な縦断面図である。この実施例では、電流リード１１Ａに付設された補助電流リード１６が、着脱可能低温端子３１を用いて室温部での操作により着脱可能として組み込まれている。
超電導コイル１が大規模なものである場合、超電導コイル１が交流損失を伴う場合、あるいは真空断熱容器４の熱侵入量が大きい場合など、液体ヘリウムの蒸発量が多くヘリウムガス量が十分多い場合には、前述の第３の実施例による補助電流リード１６に冷却用ヘリウムガスを流すことができるが、全体的に超電導装置の熱侵入量が少ない場合には、冷却用ヘリウムガスの流量を確保することが困難となる。図１３に示した第４の実施例による超電導装置用電流リードは、このように超電導装置の熱侵入量が少なく、流量の確保が困難な場合に適するものである。
【００３７】
すなわち、この実施例では、補助電流リード１６が、低温部の着脱可能低温端子３１の部分に於いて着脱可能で、図の上部に対応する室温部分から下部へと挿入することによって超電導コイルへの接続導体に接続でき、上部の室温部分へと引き上げることによって、取り外しが可能な構成となっている。正規の運転条件においては、補助電流リード１６は外部へと取り外した状態とする。この状態では補助電流リード１６による極低温部への熱侵入はないので、とくに冷却用のヘリウムガスを流す必要はない。万が一低温側リード１２が損傷した場合、すでに述べた他の実施例および参考例と同様に、保護導体１５を介して電流が流れ、超電導装置は安全に停止される。低温側リード１２が使用不能の場合には、補助電流リード１６を挿入して着脱可能低温端子３１に装着し、常温側の接続導体を常温端子３３Ａにつなぎかえることにより、再び励磁することが可能となる。
なお、図１２および図１３に示した実施例においては、電流リード１１Ａの低温側リード１２に並列接続して組み込む保護導体として、図１の第１の参考例の保護導体１５を例示しているが、図２〜図１１にそれぞれ示した第１〜第２の実施例および第２〜第９の参考例に示した保護導体を用いても、上記と同様の効果が得られることはあらためて説明するまでもなく明らかである。
【００３８】
【発明の効果】
この発明においては、上述のように、
(1) 真空断熱容器の液体ヘリウム容器内に液体ヘリウムに浸漬した状態で収納された超電導コイルに外部電源より電流を通流する超電導装置用電流リードが、良導電性金属を導体とする高温側リードと、高温酸化物超電導体を導体とする低温側リードの直列接続体で構成され、ヘリウムガスを通流して前記高温酸化物超電導体を超電導状態にして用いるものにおいて、保護導体を低温側リードに並列に電気接続して配設させるものとしたので、低温側リードの高温酸化物超電導導体が常電導転移を生じても、あるいは破損に至っても、高温酸化物超電導導体を流れていた電流は並列接続された保護導体にバイパスして流れるので、超電導コイルに蓄積されていた磁気エネルギーは保護抵抗で確実に消費されることになり、超電導コイルや、電源、真空断熱容器等の損傷を生ずることなく、安全に使用できる超電導装置用電流リードが得られることとなった。
【００３９】
また、保護導体を、ニッケル銅合金等からなる複数の導電性金属導体の線束から形成し、低温側リードを冷却するヘリウムガスの流通路に稠密に配することとし、例えば、低温側リードを筒状に形成してその内面に接する空間に保護導体を稠密に配することとすれば、保護導体は均一にかつ効率的に冷却されて、定常運転時の熱侵入量が少量に抑えられることとなる。したがって、超電導装置を損傷することなく安全に使用できる超電導装置用電流リードとして好適である。
【００４０】
(2) さらに、保護導体の線束を形成する導電性金属導体の、少なくとも一部の導体の内部に金属系超電導体、または化合物系超電導体を埋め込むこととすれば、長時間の使用に伴い、低温側リードを構成する高温酸化物超電導体が破損して通電が不能となる事態が生じても、保護導体を介して定常運転を持続させることができることとなるので、超電導装置を損傷することなく安全に使用できる超電導装置用電流リードとして、より好適である。
【００４１】
(3) また、上記のように低温側リードに保護導体を配設した電流リードに、良導電性金属を導体とする補助電流リードを付設し、それぞれの低温端子を超電導コイルに連結した低温側接続導体に電気接続することとすれば、高温酸化物超電導導体が焼損し、低温側リードが使用不能となった場合にあっても、電源と連結する常温側の接続導体を破損した電流リードの常温端子から補助電流リードの常温端子につなぎかえることにより、容易に超電導コイルの再励磁を行うことができるようになるので、超電導装置を損傷することなく安全に使用できる超電導装置用電流リードとしてさらに好適である。
【００４２】
(4) さらに、上記の付設する補助電流リードを、低温端子部で着脱可能な電流リードとすれば、保護導体を配設した低温側リードが正常に動作しているとき、付設した補助電流リードを取り外して使用できるので、補助電流リードでの熱伝導による侵入熱量を皆無として低熱侵入の電流リードの性能を確保し、かつ、高温酸化物超電導導体が焼損し使用不能となった場合においても、補助電流リードを装着し、常温側の接続導体をつなぎかえることにより、容易に超電導コイルの再励磁を行うことができるようになるので、超電導装置を損傷することなく安全に使用できる超電導装置用電流リードとしてさらに好適である。
【図面の簡単な説明】
【図１】この発明の第１の参考例による超電導装置用電流リードを組み込んだ超電導装置の模式的な縦断面図
【図２】この発明の第２の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な縦断面図
【図３】この発明の第３の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な縦断面図
【図４】この発明の第４の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な縦断面図
【図５】この発明の第５の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図で、（ａ）は全体断面図、（ｂ）は（ａ）に用いる低温側リードの断面図、（ｃ）は（ａ）に用いる他の低温側リードの断面図
【図６】この発明の第６の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図
【図７】この発明の第７の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図
【図８】この発明の第１の実施例による超電導装置用電流リードの低温側部分の基本構成を拡大して示す模式断面図で、（ａ）は縦断面図、（ｂ）は要部の横断面図
【図９】この発明の第８の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図
【図１０】この発明の第２の実施例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図
【図１１】この発明の第９の参考例による超電導装置用電流リードの低温側部分を拡大して示す模式的な横断面図
【図１２】この発明の第３の実施例による超電導装置用電流リードを組み込んだ超電導装置の模式的な断面図
【図１３】この発明の第４の実施例による超電導装置用電流リードを組み込んだ超電導装置の模式的な断面図
【図１４】従来の超電導装置用電流リードを組み込んだ超電導装置の模式的な断面図
【図１５】一般的な超電導装置の励磁回路の基本構成図
【符号の説明】
１ 超電導コイル
２ 液体ヘリウム容器
３ 液体ヘリウム
３Ｇ ヘリウムガス
４ 真空断熱容器
５，５Ａ，５Ｂ 低温側接続導体
１１，１１Ａ 電流リード
１２，１２Ａ 低温側リード
１２Ｂ，１２Ｃ 低温側リード
１２Ｄ，１２Ｅ 低温側リード
１２Ｆ 低温側リード
１３ 高温側リード
１４，１４Ａ 中間接続部
１５，１５Ａ 保護導体
１５Ｂ，１５Ｃ 保護導体
１５Ｄ，１５Ｅ 保護導体
１５Ｆ，１５Ｇ 保護導体
１６ 補助電流リード
１７Ａ，１７Ｂ 金属膜
１８Ａ，１８Ｂ 良導電性金属
１９ 低熱伝導性金属
２０，２０Ａ 中空管
３１ 着脱可能低温端子
３２，３２Ａ 低温端子
３２Ｂ 低温端子
３３，３３Ａ 常温端子
４１ 高温側接続体
４２ 低温側接続体
４３ 封止部材
４４ カバー[0001]
[Industrial applications]
The present invention relates to a current lead for a superconducting device for passing a current from a power supply at room temperature to a superconducting coil at a very low temperature, and more particularly to a current lead for a superconducting device using a high-temperature oxide superconductor on the low-temperature side.
[0002]
[Prior art]
The superconducting coil needs to be cooled and used with a cryogenic refrigerant such as liquid helium, and is normally provided in a liquid helium container provided in a liquid nitrogen shield or a vacuum insulated container provided with a high vacuum layer to prevent heat from entering. Is immersed in liquid helium. The current lead is provided to allow the excitation current to flow from the power supply at room temperature to the superconducting coil held at a cryogenic temperature, and is caused by Joule heat accompanying energization and heat conduction from the room temperature side to the cryogenic side. In order to reduce the amount of liquid helium evaporated by suppressing the invading heat, it is customary to flow a low-temperature vaporized helium gas inside the current lead to cool and remove the heat. As the conductor of the current lead, a good conductive metal such as copper or copper alloy is generally used.However, if the cross-sectional area is increased and the Joule heat is suppressed, the amount of heat penetrated by heat conduction increases and the cross-sectional area decreases. If the amount of heat penetrated by heat conduction is suppressed, Joule heat increases, so there is a limit to the amount of liquid helium that can be reduced. On the other hand, a high-temperature oxide superconductor is arranged on the conductor of the low-temperature side lead and connected in series with the high-temperature side lead having a conductor of good conductivity as a conductor. -292610) has attracted attention as a drastic reduction in the amount of evaporation of liquid helium.
[0003]
FIG. 14 is a cross-sectional view schematically showing a superconducting device incorporating a conventional current lead for a superconducting device. The superconducting coil 1 is stored in the liquid helium container 2 of the vacuum heat insulating container 4 in a state of being immersed in the liquid helium 3, and is maintained in a superconducting state. The current lead 11 is formed by a series connection in which a high-temperature side lead 13 made of a good conductive metal conductor such as copper or a copper alloy and a low-temperature side lead 12 made of a high-temperature oxide superconducting conductor are conductively connected at an intermediate connection portion 14. A current is supplied to the superconducting coil 1 by connecting the low-temperature terminal 32 to the low-temperature side connection conductor 5 connected to the superconducting coil 1 and connecting the room-temperature terminal 33 to a power supply (not shown). Further, the current lead 11 is cooled by introducing a low-temperature helium gas 3G evaporated and vaporized in the liquid helium container 2 from the lower end of the low-temperature side lead 12.
[0004]
If a ceramic-based high-temperature superconductor such as an yttrium-based or bismuth-based superconductor is used as the high-temperature oxide superconductor of the low-temperature side lead 12, the superconducting state is obtained at about liquid nitrogen temperature or lower, so that Joule heat is reduced to zero. Since the thermal conductivity is two to three orders of magnitude smaller than that of copper, the heat penetrated by conduction is greatly reduced. When applied as a conductor for the low-temperature side lead 12, the bulk type high-temperature oxide superconductor obtained by compression-molding and heat-treating a high-temperature superconducting material powder and the sheath-type heat-treated by compression-molding silver or an alloy thereof as a sheath material are used. High temperature oxide superconductors are known. Among them, the sheath-type high-temperature oxide superconductor has a critical current density several tens times larger than that of the bulk-type high-temperature oxide superconductor and is advantageous for downsizing, but silver or its alloy used as the sheath material is used. And so on, the high-temperature oxide superconductor cannot take advantage of the low thermal conductivity characteristic. Therefore, a bulk type high temperature oxide superconductor is generally used as the conductor of the low temperature side lead 12.
[0005]
[Problems to be solved by the invention]
In the current lead configured as above, no Joule heat is generated in the low-temperature side lead, and the thermal conductivity is extremely small and the heat penetrated by conduction is also small, so the evaporation of liquid helium by the current lead can be suppressed to a very small amount. Thus, the superconducting device can be made extremely efficient.
[0006]
However, even in the current lead configured as described above, when the connected superconducting coil is energized, if the high-temperature oxide superconducting conductor of the low-temperature side lead transitions from the superconducting state to the normal conducting state for some reason, the normal conducting state may occur. Since the electrical resistance of the conductor is 100 times or more higher than that of a metal, there is a risk that a large amount of Joule heat is generated, the temperature of the conductor rises, and if the current supplied is not instantaneously attenuated, the conductor may burn out.
[0007]
On the other hand, in a general superconducting device, as shown in a basic configuration diagram of an excitation circuit in FIG. 15, a superconducting coil 21 is connected to a power supply 23 via a pair of current leads 22 and 22A to excite the superconducting coil. A protection resistor 24 is incorporated in parallel with 21. When the superconducting coil 21 transitions from the superconducting state to the normal conducting state for some reason, the switch 25 is turned off to form a closed circuit composed of the superconducting coil 21 and the protection resistor 24, and is stored in the excited superconducting coil 21. The superconducting coil 21 and the vacuum heat-insulating container 26 are prevented from being damaged by extracting a large amount of the generated magnetic energy to the protection resistor 24 arranged at the room temperature outside the vacuum heat-insulating container 26.
[0008]
Therefore, when the high-temperature oxide superconducting conductor on the low-temperature side lead of the current lead transitions from the superconducting state to the normal conducting state as described above, even if this is detected and the switch 25 is shut off, the current flowing through the superconducting coil 21, that is, The current flowing through the current lead is attenuated by a time constant determined by the inductance of the superconducting coil 21 and the resistance value of the protection resistor 24, and instantaneous attenuation cannot be performed with the current lead protected. For this reason, the temperature of the high-temperature oxide superconducting conductor rises sharply, and the possibility of burning increases. When the current lead burns out, the closed circuit composed of the superconducting coil 21 and the protection resistor 24 shown in FIG. 15 is opened at the current lead 22 or 22A. And the risk of damage to the superconducting coil 21 such as insulation breakdown and damage to the power supply 23 and the vacuum insulation container 26 increases.
[0009]
The present invention has been made in view of the above problems, and an object thereof is to provide a series connection of a high-temperature side lead using a good conductive metal as a conductor and a low-temperature side lead using a high-temperature oxide superconductor as a conductor. In a current lead for a superconducting device composed of the above, even if the high-temperature oxide superconductor may transition to the normal conducting state for some reason when energized, burning due to abnormal temperature rise is prevented, and the superconducting coil, power supply, or heat insulation An object of the present invention is to provide a current lead for a superconducting device that can be used safely without causing damage to a vacuum vessel.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
(1) A current lead for a superconducting device that allows current to flow from an external power supply to a superconducting coil housed in a liquid helium container in a vacuum insulated container immersed in liquid helium. Composed of a series connection of a lead and a low-temperature lead with a high-temperature oxide superconductor as the conductor, in which helium gas flows and the high-temperature oxide superconductor is used in the superconducting state. Along with disposing the protective conductor, the protective conductor is formed from a bundle of a plurality of conductive metal conductors made of, for example, bronze, beryllium copper alloy, nickel copper alloy, or the like, and helium gas for cooling the low-temperature side lead is used. The low-temperature side lead is formed in a cylindrical shape, and the protective conductor is densely arranged in the space in contact with the inner surface. Forming the side lead in a cylindrical shape and disposing a sealing member made of an airtight member at the center in the cross section inside the low temperature side lead, between the sealing member and the inner surface of the low temperature side lead, A space serving as a helium gas flow path for cooling the low-temperature side lead is formed, and the protective conductor is densely arranged in this space.
[0011]
(2) Further, a metal-based superconductor or a compound-based superconductor is embedded in at least a part of the conductive metal conductor forming the wire bundle.
(3) In addition, the current lead for the superconducting device is provided with an auxiliary current lead having a current capacity to flow through the superconducting coil and made of a good conductive metal as a conductor, and the low-temperature terminals of these current leads are superconductive. It shall be electrically connected to the low-temperature side connection conductor connected to the coil.
[0012]
(4) Further, as described above, the auxiliary current lead attached to the current lead for the superconducting device is configured to be detachable at the low-temperature terminal portion by operating at room temperature.
[0013]
[Action]
Assuming that the current lead for the superconducting device is disposed by electrically connecting the protective conductor in parallel with the low-temperature side lead as described in (1) above, the high-temperature oxide superconducting conductor of the low-temperature side lead causes a normal conduction transition. Even so, the current flowing through the high-temperature oxide superconductor is bypassed to the protection conductor connected in parallel, so the magnetic energy stored in the superconducting coil is reliably consumed by the protection resistor installed outside. It becomes. Therefore, with this configuration, it is possible to provide a current lead for a superconducting device that can be used safely without causing damage to the superconducting coil, the vacuum insulation container, and the like.
[0014]
In addition, the protective conductor is formed from a bundle of a plurality of conductive metal conductors made of, for example, bronze, beryllium copper alloy, nickel copper alloy, or the like, and is densely arranged in the helium gas flow path that cools the low-temperature side lead. For example, if the low-temperature side lead is formed in a cylindrical shape and the protective conductor is densely arranged in a space in contact with the inner surface, by forming the protective conductor from a large number of wire bundles, the surface area per sectional area of the protective conductor is large. That is, by being densely arranged in the helium gas flow passage, uniform and efficient cooling can be achieved. Therefore, the amount of heat penetration during the steady operation is suppressed to a small amount, and the current can be effectively bypassed when the high-temperature oxide superconducting conductor undergoes a normal conduction transition.
[0015]
Furthermore, as described in (2) above, if a metal-based superconductor or a compound-based superconductor is to be embedded inside at least a part of the conductive metal conductor forming the bundle of protective conductors, the embedded conductor may be embedded. The protection conductor is also in a superconducting state in a portion below the critical temperature of the superconductor. Therefore, even if the high-temperature oxide superconductor constituting the low-temperature side lead is damaged due to the occurrence of cracks due to thermal cycling due to prolonged use and the current cannot be supplied, the low-temperature side lead can be repaired. Thus, steady operation can be continued through the protective conductor without increasing the temperature, and an increase in heat intrusion can be suppressed.
[0016]
Also, as described in (3) above, these current leads are provided with auxiliary current leads made of a good conductive metal as conductors, and each low-temperature terminal is electrically connected to the low-temperature side connection conductor connected to the superconducting coil. In other words, when the high-temperature oxide superconductor is burned out and cannot be used, the normal-temperature connection conductor connected to the power supply is connected from the normal-temperature terminal of the damaged current lead to the normal-temperature terminal of the auxiliary current lead. Thus, the superconducting coil can be easily re-excited.
[0017]
Further, if the attached auxiliary current lead is a detachable current lead at the low-temperature terminal portion as described in (4) above, the attached auxiliary current lead can be attached and detached at the time of normal energizing operation using the low-temperature side lead provided with the protective conductor. Since the used auxiliary current lead can be removed and used, the amount of heat penetrated by heat conduction in the auxiliary current lead can be eliminated. Further, when the high-temperature oxide superconducting conductor becomes burnt and becomes unusable, an auxiliary current lead is attached and the connection conductor on the normal temperature side is connected, so that the superconducting coil can be re-excited.
[0018]
【Example】
Hereinafter, embodiments and reference examples of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic longitudinal sectional view of a superconducting device incorporating a current lead for a superconducting device according to a first embodiment of the present invention. Components having the same functions as those of the conventional example described above are denoted by the same reference numerals, and redundant description will be omitted.
[0019]
In this figure, a protective conductor 15 made of a metal material such as stainless steel is electrically connected to the low-temperature side lead 12 in parallel. Since the high-temperature oxide superconducting conductor constituting the low-temperature side lead 12 has zero electric resistance in the superconducting state in normal operation, the current flowing through the current lead 11A flows through the high-temperature oxide superconducting conductor and does not flow through the protective conductor 15. However, when the high-temperature oxide superconducting conductor transitions to the normal conducting state, the high-temperature oxide superconducting conductor is ceramic and exhibits an extremely high electrical resistivity close to that of an insulator, so that the current flowing through the current lead 11A is bypassed to the protective conductor 15. It will be. Therefore, the superconducting coil 21 is separated from the power supply 23 by shutting off the switch 25 as shown in FIG. 15 together with the transition of the high-temperature oxide superconducting conductor to the normal conducting state, and the magnetic energy stored in the superconducting coil 21 is changed. Is taken out to the protection resistor 24, the current flowing through the low-temperature side lead 12 during this time is almost zero, so that the apparatus can be safely stopped without causing an excessive rise in temperature. Even if the low-temperature side lead 12 is damaged, the magnetic energy is taken out to the protection resistor via the protection conductor, so that the device must be safely stopped without damaging the superconducting coil, the power supply, or the vacuum insulation container. Can be.
[0020]
As described above, the protective conductor 15 relates to the method of protecting the superconducting coil 21 constituting the superconducting device, and its material and dimensions are determined by the maximum stored energy of the superconducting coil 21, the resistance value of the protection resistor 24, and the low-temperature side. It is determined by the allowable heat intrusion of the lead 12 in the normal state, the allowable maximum temperature of the protective conductor 15, and the like. For example, copper or its alloy, aluminum or its alloy, etc. have a small electric resistivity and a high current density, so that the size as the protective conductor 15 can be small. However, since these have a high thermal conductivity, they have a high thermal conductivity. There is a possibility that the amount of invading heat becomes excessive. In this respect, the use of a stainless steel material is effective in suppressing the amount of heat that enters, but care must be taken to prevent the temperature rise during energization from becoming excessive.
[0021]
The protection conductor 15 is formed in a cylindrical shape, and a low-temperature helium gas is guided into the protection conductor 15 through a communication groove (not shown) provided in the low-temperature terminal 32, and a flow path (not shown) provided in the intermediate connection portion 14 is provided. If flow is made to the high-temperature side lead 13 through the groove, the high-temperature oxide superconducting conductor constituting the low-temperature side lead 12 and further the protective conductor 15 are effectively cooled, and the amount of heat entering during steady operation is effectively reduced. Is done.
[0022]
FIG. 2 is an enlarged schematic longitudinal sectional view showing a low temperature side portion of a current lead for a superconducting device according to a second reference example of the present invention. The difference between the first embodiment and the first embodiment is that the protective conductor 15 made of stainless steel is provided with metal films 17A and 17B made of a highly conductive metal at the electrical connection part. 17A is connected to the intermediate connector 14 made of a good conductive metal, and the metal film 17B is connected to the low temperature terminal 32 made of a good conductive metal by parallel connection with the low temperature side lead 12 made of a high temperature oxide superconducting conductor. Are electrically connected. In order to electrically connect the protection conductor 15 made of stainless steel directly to the intermediate connector 14 and the low-temperature terminal 32, it is extremely difficult to perform solder connection, so that it is necessary to perform welding connection. However, when the welding connection is performed, the ambient temperature becomes high. Therefore, there is a very high possibility that the high-temperature oxide superconducting conductor constituting the low-temperature side lead 12 undergoes a composition change and the superconducting characteristics are greatly reduced. On the other hand, as in the present embodiment, if the solder connection is made by using the protective conductor 15 provided in advance with the metal films 17A and 17B made of a highly conductive metal at the electric connection portion, the high-temperature oxide superconducting conductor The connection can be made with a small connection resistance without impairing the characteristics of the above. In addition, as a method of forming the metal films 17A and 17B made of a highly conductive metal on the electrical connection portion of the protective conductor 15 made of a metal material such as a stainless steel material, a plating method, a vapor deposition method, a sputtering method, a thermal spraying method, or the like is used. Used.
[0023]
FIG. 3 is a schematic longitudinal sectional view showing, on an enlarged scale, a low temperature side portion of a current lead for a superconducting device according to a third reference example of the present invention. The feature of the present reference example is that the protective conductor 15A has good conductive metals 18A and 18B made of copper or a copper alloy at both ends serving as electrical connection parts, and a low heat conductive metal made of a stainless steel material or the like at the center. 19 in that they are connected in series. In this configuration, since the good conductive metals 18A and 18B are used for the electrical connection portion, the electrical connection can be easily made to the intermediate connector 14 and the low-temperature terminal 32 by solder connection as in the second reference example. Since the low thermal conductive metal 19 is provided at the center, the amount of heat that enters the low-temperature portion via the protective conductor 15A can be effectively suppressed. It should be noted that joining between different metals of the good conductive metals 18A and 18B and the low thermal conductive metal 19 can be relatively easily performed by a friction welding method or an electrocompression bonding method.
[0024]
FIG. 4 is a schematic longitudinal sectional view showing, on an enlarged scale, a low temperature side portion of a current lead for a superconducting device according to a fourth embodiment of the present invention. The feature of this embodiment is that the protection conductor 15B is formed of a stainless steel material having a bellows shape and having flexibility. When the current lead is used by being incorporated in a superconducting device, each part of the current lead is cooled by the low-temperature helium gas, so that it thermally contracts in accordance with the thermal expansion coefficient of the constituent material and the cooling temperature. Even between the low-temperature side lead 12 and the protective conductor 15B, a difference in the amount of heat shrinkage occurs due to a difference in the constituent materials, so that thermal stress is exerted on each other. If the thermal stress is excessive, the high-temperature oxide superconducting conductor having poor strength is used. The low-temperature side lead 12 may be damaged. In the configuration of the present reference example, since the protective conductor 15B is configured to maintain flexibility, even if a difference occurs in the amount of thermal contraction, the thermal stress is reduced, and the low-temperature side lead 12 is damaged as described above. Can be avoided. Further, since the protection conductor 15B is formed in a bellows shape, the effect of further reducing the amount of heat penetration due to heat conduction through the protection conductor 15B can be obtained. In this configuration, the protection conductor 15B made of a stainless steel material is illustrated as having flexibility, but the protection conductor 15B is formed of a good conductive metal, or as shown in the third reference example. It is needless to say that the same effect can be obtained even if it is made of a series-connected body in which a metal and a low heat conductive metal are joined, if the structure is kept flexible.
[0025]
FIGS. 5A and 5B are schematic cross-sectional views showing, on an enlarged scale, a low-temperature side portion of a current lead for a superconducting device according to a fifth reference example of the present invention, wherein FIG. 5A is an overall cross-sectional view, and FIG. (C) is a cross-sectional view of another low-temperature side lead used in (a). In the present reference example, a plurality of stainless steel round bar-shaped protection conductors 15C as shown in (b) or a plurality of stainless steel cylindrical protection conductors 15D as shown in (c) are embedded. A low-temperature side lead 12A made of a high-temperature oxide superconducting conductor is disposed inside the hollow tube 20, cooled by the introduced helium gas, and maintained in a superconducting state. In this configuration, since the protection conductor 15C or 15D and the low-temperature side lead 12A are electrically connected not only at the upper end and lower end but also over the entire length in the longitudinal direction, it is effective as a parallel connection body, and is formed integrally. Therefore, the mechanical strength of the essentially brittle high-temperature oxide superconducting conductor is reinforced by the stainless steel protective conductor 15C or 15D, and the low-temperature side lead 12A is prevented from being mechanically damaged. Further, the low-temperature side lead 12A in which the cylindrical protection conductor 15D is buried as shown in (c) is effectively cooled by the helium gas flowing on the outer periphery and the helium gas flowing inside the protection conductor 15D.
[0026]
FIG. 6 is an enlarged schematic cross-sectional view showing a low-temperature side portion of a current lead for a superconducting device according to a sixth embodiment of the present invention. In the present reference example, a plurality of round bar-shaped bulk type high-temperature oxide superconducting conductors, a low-temperature side lead 12B and a plurality of stainless steel round bar-shaped protective conductors 15E are densely packed inside the hollow tube 20A. The hollow tube 20A is disposed and electrically and mechanically connected at both ends in the longitudinal direction. The hollow tube 20A is cooled by a helium gas flowing through a space inside the hollow tube 20A and used in a superconducting state.
[0027]
FIG. 7 is an enlarged schematic cross-sectional view showing a low-temperature side portion of a current lead for a superconducting device according to a seventh embodiment of the present invention. The difference between the sixth embodiment and the sixth embodiment is that a plurality of round bar-shaped sheathed high-temperature oxide superconductors are used instead of the low-temperature side lead 12B composed of a plurality of round bar-shaped bulk high-temperature oxide superconductors. The low-temperature-side lead 12C is used, and the others are the same.
[0028]
In the current lead for the superconducting device according to the sixth and seventh embodiments, the ratio of the total cross-sectional area of the low-temperature side lead 12B (or 12C) and the protective conductor 15E in the hollow tube 20A is 50%. % Or more, and the helium gas to be introduced flows almost uniformly distributed in the gap between the low-temperature side lead 12B (or 12C) and the protective conductor 15E which are uniformly dispersed. Therefore, even if the flow rate of the helium gas is small, the flow rate is increased, the heat transfer coefficient is improved, and cooling is performed effectively.
[0029]
FIGS. 8A and 8B are schematic sectional views showing, on an enlarged scale, the basic structure of the low-temperature side portion of the current lead for a superconducting device according to the first embodiment of the present invention. FIG. 8A is a longitudinal sectional view, and FIG. FIG. In this configuration, as shown in (a), the low-temperature side lead 12D formed in a cylindrical shape is fitted and soldered to the intermediate connection portion 14A on the high-temperature side and to the low-temperature terminal 32B on the low-temperature side. I have. A sealing member 43 formed of an air-tight member is disposed in the center of the inside of the low-temperature side lead 12D, and a large number of nickel-copper alloys are formed in a space between the sealing member 43 and the inner surface of the low-temperature side lead 12D. Protection conductor 15F is incorporated. One end of the protective conductor 15F is conductively connected to the intermediate connector 14A via the high-temperature side connector 41, and the other end is conductively connected to the low-temperature terminal 32B via the low-temperature connector 42. The lead 12D electrically constitutes a parallel connection body. Further, as can be seen from (b), the protective conductors 15F made of many nickel-copper alloys are densely inserted and arranged in the space between the sealing member 43 and the inner surface of the low-temperature side lead 12D. As shown in a), the helium gas 3G introduced through the through-hole provided in the low-temperature terminal 32B and sent to the high-temperature side lead through the through-hole provided in the intermediate connector 14A removes the invading heat. Is done. In this configuration, the ratio of the cross-sectional area of the protective conductor 15F in the cross section of the space between the sealing member 43 and the inner surface of the low-temperature side lead 12D has reached 70% or more, and the helium gas 3G is uniformly distributed in each part. Since the protection conductor 15F flows, the protection conductor 15F and the low-temperature side lead 12D are uniformly cooled, and the conduction heat that enters the low-temperature terminal 32B through these is reduced.
[0030]
FIG. 9 is an enlarged schematic cross-sectional view showing a low-temperature side portion of a current lead for a superconducting device according to an eighth embodiment of the present invention. In the present embodiment, a large number of protective conductors 15F made of a nickel-copper alloy are densely inserted and arranged in a space between the low-temperature side lead 12E formed in a columnar shape and the outer cover 44. Also in the present configuration, similarly to the first embodiment, the protective conductor 15F connected in parallel to the low-temperature side lead 12E is effectively cooled by the helium gas, and the invasion heat is reduced. Further, in the present configuration, the cover 44 can be formed arbitrarily after disposing the protective conductor 15F on the outer peripheral portion of the low-temperature side lead 12E, so that there is an advantage that it is easy to densely insert and dispose the protective conductor 15F. .
[0031]
FIG. 10 is an enlarged schematic cross-sectional view showing a low-temperature side portion of a current lead for a superconducting device according to a second embodiment of the present invention. In the present embodiment, similarly to the above-described first embodiment, the protection conductor 15G is arranged in the gap between the inside of the cylindrical low-temperature side lead 12D and the sealing member 43. The difference between the first embodiment and the first embodiment lies in the configuration of the protective conductor 15G. In the first embodiment, a large number of nickel copper alloys are used. The point is that a large number of nickel-copper alloys in which Nb-Ti alloy fine wires of a metallic superconductor are embedded are used. In this configuration, since the Nb-Ti alloy is in a superconducting state in a low temperature state, even if the high temperature oxide superconductor constituting the low temperature side lead 12D deteriorates and becomes unable to conduct electricity, the low temperature side lead 12D is There is an advantage that steady energization can be continued via the protective conductor 15G without repair.
[0032]
In the present embodiment, the case where the Nb-Ti alloy of the metal-based superconductor is embedded in a large number of nickel-copper alloys is exemplified, but the Nb-Ti alloy is embedded in all of the many nickel-copper alloys. It is not necessary to provide the same effect, even if only a part of the nickel copper alloy is buried according to the current carrying capacity. The superconductor to be embedded is not limited to the Nb-Ti alloy, but may be a metal-based superconductor such as an Nb-Ti-Ta alloy or Nb-Ti-Ta alloy. Three Sn, Nb Three Even when a compound superconductor such as Al is used, the same effect can be obtained in accordance with the critical temperature and the current carrying capacity of the superconductor.
[0033]
FIG. 11 is an enlarged schematic cross-sectional view showing a low-temperature side portion of a current lead for a superconducting device according to a ninth embodiment of the present invention. In the present embodiment, a large number of protective conductors 15F made of a nickel-copper alloy are densely arranged in the gap and the innermost part of the low-temperature side lead 12F formed in a double cylindrical shape. In this configuration, since the cross-sectional area of the low-temperature side lead 12F and the protective conductor 15F can be relatively large, it is effective as a current lead for a superconducting device having a large current carrying capacity.
[0034]
In the first and second embodiments and the eighth and ninth reference examples shown in FIGS. 8 to 11, a large number of nickel copper alloys are used as the protective conductor. The present invention is not limited to alloys, and it is needless to say that the same effect can be obtained with a conductive metal conductor such as bronze and beryllium copper alloy.
FIG. 12 is a schematic longitudinal sectional view of a superconducting device incorporating a current lead for a superconducting device according to a third embodiment of the present invention. An auxiliary current lead 16 made of a good conductive metal is attached to a current lead 11A comprising a high-temperature side lead 13 and a low-temperature side lead 12 and having a protective conductor 15 electrically connected in parallel with the low-temperature side lead 12. Each of the low-temperature terminals is electrically connected to the low-temperature-side connection conductor 5A connected to the superconducting coil 1. In this configuration, when the high-temperature oxide superconductor constituting the low-temperature side lead 12 is burned and becomes unusable, the normal-temperature side connection conductor connected to the power supply is connected to the auxiliary current from the normal-temperature terminal 33 of the damaged current lead 11A. By reconnecting to the room temperature terminal 33A of the lead 16, re-excitation of the superconducting coil becomes possible. The high-temperature oxide superconducting conductor constituting the low-temperature side lead 12 burns out and becomes unusable. To replace this, it is necessary to separate and reconnect at the low-temperature terminal 32 in an extremely low-temperature atmosphere. It is necessary to stop the cooling of the device and raise the temperature to bring the low-temperature terminal 32 to room temperature, which is extremely uneconomical. However, if the auxiliary current lead 16 is provided, it is easy only by changing the connection conductor on the normal temperature side. Can be re-excited.
[0035]
By providing the auxiliary current lead 16, even when the current lead 11A is operating normally, heat enters the cryogenic part through heat conduction through the auxiliary current lead 16, but in this case, Since no current flows, no Joule heat is generated, and a small amount of low-temperature helium gas may be supplied to cool so as to remove minute components due to heat conduction.
[0036]
FIG. 13 is a schematic longitudinal sectional view of a superconducting device incorporating a current lead for a superconducting device according to a fourth embodiment of the present invention. In this embodiment, the auxiliary current lead 16 attached to the current lead 11A is detachably incorporated by using a detachable low-temperature terminal 31 at a room temperature.
When the amount of evaporation of liquid helium is large and the amount of helium gas is sufficiently large, such as when the superconducting coil 1 is large-scale, when the superconducting coil 1 involves an AC loss, or when the heat infiltration amount of the vacuum insulation container 4 is large. The cooling helium gas can flow through the auxiliary current lead 16 according to the third embodiment described above. However, when the heat penetration of the superconducting device is small as a whole, the flow rate of the cooling helium gas is secured. It will be difficult to do. The current lead for a superconducting device according to the fourth embodiment shown in FIG. 13 is suitable when the amount of heat penetration of the superconducting device is small and it is difficult to secure a flow rate.
[0037]
That is, in this embodiment, the auxiliary current lead 16 is detachable at the detachable low-temperature terminal 31 of the low-temperature portion, and is inserted into the lower portion from the room temperature portion corresponding to the upper portion of the drawing to connect to the superconducting coil. It can be connected to the connection conductor and can be removed by pulling it up to the upper room temperature portion. Under normal operating conditions, the auxiliary current lead 16 is detached to the outside. In this state, there is no heat intrusion into the cryogenic portion by the auxiliary current lead 16, so that it is not necessary to flow helium gas for cooling. Should the low-temperature side lead 12 be damaged, a current flows through the protective conductor 15 and the superconducting device is safely stopped, as in the other embodiments and reference examples already described. When the low-temperature side lead 12 cannot be used, the auxiliary current lead 16 can be inserted and attached to the detachable low-temperature terminal 31, and the connection conductor on the normal temperature side can be connected to the normal-temperature terminal 33A to re-excit. It becomes.
In the embodiment shown in FIGS. 12 and 13, the protective conductor 15 of the first reference example of FIG. 1 is illustrated as a protective conductor connected in parallel to the low-temperature side lead 12 of the current lead 11A. However, it will be described again that the same effect as described above can be obtained by using the protective conductors shown in the first and second embodiments and the second to ninth reference examples shown in FIGS. It is obvious without need.
[0038]
【The invention's effect】
In the present invention, as described above,
(1) The current lead for the superconducting device, which passes current from an external power supply to the superconducting coil housed in the liquid helium container of the vacuum insulated container while immersed in liquid helium, has a high-temperature side with a conductive metal as a conductor. A lead and a series connection of a low-temperature side lead having a high-temperature oxide superconductor as a conductor, wherein the protective conductor is used as a low-temperature side lead when the helium gas flows and the high-temperature oxide superconductor is used in a superconducting state. Even if the high-temperature oxide superconducting conductor of the low-temperature side lead undergoes normal conduction transition or breaks, the current flowing through the high-temperature oxide superconducting conductor is The magnetic flux stored in the superconducting coil is reliably consumed by the protective resistor because it flows by bypassing the parallel-connected protective conductor, and the superconducting coil and power supply Thus, a current lead for a superconducting device which can be used safely without causing damage to a vacuum insulation container or the like can be obtained.
[0039]
Further, the protective conductor is formed from a wire bundle of a plurality of conductive metal conductors made of a nickel copper alloy or the like, and is densely arranged in a helium gas flow path for cooling the low-temperature side lead. If the protective conductors are densely arranged in a space in contact with the inner surface of the protective conductor, the protective conductors are uniformly and efficiently cooled, and the amount of heat penetration during steady operation is suppressed to a small amount. Become. Therefore, it is suitable as a current lead for a superconducting device that can be used safely without damaging the superconducting device.
[0040]
(2) Furthermore, if the metal-based superconductor or the compound-based superconductor is embedded in at least a part of the conductive metal conductor forming the protective conductor wire bundle, with long-term use, Even if the high-temperature oxide superconductor constituting the low-temperature side lead breaks and becomes unable to conduct electricity, steady operation can be continued through the protective conductor, so that the superconducting device is not damaged. It is more suitable as a current lead for a superconducting device that can be used safely.
[0041]
(3) As described above, a current lead having a protective conductor disposed on the low-temperature side lead is provided with an auxiliary current lead having a conductive material of good conductivity as a conductor, and each low-temperature terminal is connected to a superconducting coil. If the high-temperature oxide superconductor is burned out and the low-temperature side lead becomes unusable, the normal-temperature side connection conductor connected to the power supply will be damaged if the current lead is damaged. By switching from the room temperature terminal to the room temperature terminal of the auxiliary current lead, the superconducting coil can be easily re-excited, so that it can be used safely without damaging the superconducting device. It is suitable.
[0042]
(4) Further, if the auxiliary current lead to be attached is a current lead that can be attached to and detached from the low-temperature terminal portion, the auxiliary current lead that is attached when the low-temperature side lead provided with the protective conductor is operating normally. Since it can be used by removing it, there is no penetration heat due to heat conduction in the auxiliary current lead, ensuring the performance of the current lead with low heat penetration, and even when the high-temperature oxide superconductor is burned out and becomes unusable, By mounting the auxiliary current lead and reconnecting the connection conductor on the normal temperature side, the superconducting coil can be easily re-excited, so that the current for the superconducting device can be used safely without damaging the superconducting device. It is more suitable as a lead.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a superconducting device incorporating a current lead for a superconducting device according to a first embodiment of the present invention.
FIG. 2 is an enlarged schematic longitudinal sectional view showing a low temperature side portion of a current lead for a superconducting device according to a second embodiment of the present invention;
FIG. 3 is a schematic longitudinal sectional view showing, on an enlarged scale, a low temperature side portion of a current lead for a superconducting device according to a third embodiment of the present invention;
FIG. 4 is an enlarged schematic longitudinal sectional view showing a low temperature side portion of a current lead for a superconducting device according to a fourth embodiment of the present invention;
FIGS. 5A and 5B are schematic cross-sectional views showing, on an enlarged scale, a low-temperature side portion of a current lead for a superconducting device according to a fifth reference example of the present invention, wherein FIG. 5A is an overall cross-sectional view and FIG. (C) is a cross-sectional view of another low-temperature side lead used in (a).
FIG. 6 is an enlarged schematic cross-sectional view showing a low-temperature side portion of a current lead for a superconducting device according to a sixth embodiment of the present invention;
FIG. 7 is an enlarged schematic cross-sectional view showing a low-temperature side portion of a current lead for a superconducting device according to a seventh embodiment of the present invention;
FIGS. 8A and 8B are enlarged schematic sectional views showing a basic configuration of a low-temperature side portion of a current lead for a superconducting device according to a first embodiment of the present invention, wherein FIG. 8A is a longitudinal sectional view, and FIG. Cross section
FIG. 9 is an enlarged schematic cross-sectional view showing a low-temperature side portion of a current lead for a superconducting device according to an eighth embodiment of the present invention;
FIG. 10 is an enlarged schematic cross-sectional view showing a low temperature side portion of a current lead for a superconducting device according to a second embodiment of the present invention.
FIG. 11 is an enlarged schematic cross-sectional view showing a low-temperature side portion of a current lead for a superconducting device according to a ninth embodiment of the present invention;
FIG. 12 is a schematic sectional view of a superconducting device incorporating a current lead for a superconducting device according to a third embodiment of the present invention.
FIG. 13 is a schematic sectional view of a superconducting device incorporating a current lead for a superconducting device according to a fourth embodiment of the present invention.
FIG. 14 is a schematic cross-sectional view of a superconducting device incorporating a conventional current lead for a superconducting device.
FIG. 15 is a basic configuration diagram of an excitation circuit of a general superconducting device.
[Explanation of symbols]
1 superconducting coil
2 Liquid helium container
3 liquid helium
3G helium gas
4 Vacuum insulated container
5,5A, 5B Low temperature connection conductor
11,11A current lead
12,12A Low temperature side lead
12B, 12C Low temperature side lead
12D, 12E Low temperature lead
12F Low temperature lead
13 High temperature side lead
14, 14A Intermediate connection
15, 15A protective conductor
15B, 15C Protection conductor
15D, 15E Protective conductor
15F, 15G protective conductor
16 Auxiliary current lead
17A, 17B metal film
18A, 18B Good conductive metal
19 Low thermal conductive metal
20,20A hollow tube
31 Removable low-temperature terminal
32,32A low temperature terminal
32B low temperature terminal
33,33A room temperature terminal
41 High-temperature side connector
42 Low temperature connection
43 Sealing member
44 cover

Claims (5)

真空断熱容器の液体ヘリウム容器内に液体ヘリウムに浸漬して収納された超電導コイルに外部電源より電流を通流する超電導装置用電流リードで、良導電性金属を導体とする高温側リードと、高温酸化物超電導体を導体とする低温側リードの直列接続体で構成され、ヘリウムガスを通流して前記高温酸化物超電導体を超電導状態として用いるものにおいて、前記低温側リードに並列に電気接続された保護導体が配設され、かつ、前記低温側リードが筒状に形成されるとともに前記低温側リードの内部の横断面での中心部に気密な部材よりなる封止部材が配されて、この封止部材と前記低温側リードの内面との間に、前記低温側リードを冷却するヘリウムガスの流通路となる空間が形成され、かつ、前記保護導体が複数の導電性金属導体の線束からなるとともに前記空間に稠密に配されてなることを特徴とする超電導装置用電流リード。A current lead for a superconducting device that allows current to flow from an external power supply to a superconducting coil that is immersed in liquid helium in a liquid helium container of a vacuum insulated container. It is composed of a series connection of a low-temperature side lead having an oxide superconductor as a conductor, and is electrically connected in parallel to the low-temperature side lead in the case where the high-temperature oxide superconductor is used in a superconducting state by flowing helium gas. A protective conductor is provided, and the low-temperature side lead is formed in a cylindrical shape, and a sealing member made of an air-tight member is provided at a central portion of a cross section inside the low-temperature side lead. A space is formed between the stop member and the inner surface of the low-temperature side lead as a helium gas flow passage for cooling the low-temperature side lead, and the protective conductor is a bundle of a plurality of conductive metal conductors. Superconducting device for current leads, characterized by comprising been densely disposed in the space together with Ranaru. 請求項１に記載の超電導装置用電流リードにおいて、保護導体をなす前記の線束を形成する複数の導電性金属導体の少なくとも一部が、内部に金属系超電導体、または化合物系超電導体を埋め込んでなることを特徴とする超電導装置用電流リード。2. The current lead for a superconducting device according to claim 1, wherein at least a part of the plurality of conductive metal conductors forming the wire bundle forming the protective conductor has a metal superconductor or a compound superconductor embedded therein. A current lead for a superconducting device, comprising: 請求項１または２のいずれかに記載の超電導装置用電流リードにおいて、保護導体を形成する前記導電性金属導体が、ブロンズ、ベリリウム銅合金、またはニッケル銅合金のうちのいずれか一つからなることを特徴とする超電導装置用電流リード。3. The current lead for a superconducting device according to claim 1, wherein the conductive metal conductor forming the protection conductor is made of one of bronze, beryllium copper alloy, and nickel copper alloy. 4. A current lead for a superconducting device. 請求項１ないし３のいずれかに記載の超電導装置用電流リードにおいて、前記超電導コイルに通流する通電電流容量を有し、良導電性金属を導体とする補助電流リードが付設され、かつ各々の電流リードの低温端子が前記超電導コイルに連結された低温側接続導体に電気的に接続されていることを特徴とする超電導装置用電流リード。The current lead for a superconducting device according to any one of claims 1 to 3, further comprising an auxiliary current lead having a current carrying capacity to flow through the superconducting coil and having a conductive metal as a conductor. A current lead for a superconducting device, wherein a low-temperature terminal of the current lead is electrically connected to a low-temperature side connection conductor connected to the superconducting coil. 請求項４に記載の超電導装置用電流リードにおいて、付設された補助電流リードが、室温部での操作により低温端子部で着脱可能に構成された電流リードであることを特徴とする超電導装置用電流リード。5. The current lead for a superconducting device according to claim 4, wherein the auxiliary current lead attached is a current lead configured to be detachable at a low-temperature terminal portion by operating at a room temperature portion. Lead.
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US20150099640A1 (en) * 2012-05-29 2015-04-09 Furukawa Electric Co., Ltd. Cooling container

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JP2002270913A (en) * 2001-03-09 2002-09-20 Hitachi Ltd Superconductive coil unit and mri device
JP4296270B2 (en) * 2004-01-26 2009-07-15 独立行政法人産業技術総合研究所 Magnetization measuring device using helium-3 refrigerator
JP5230925B2 (en) * 2006-11-02 2013-07-10 新日鐵住金株式会社 Superconducting current-carrying member with excellent deformability
JP2008159828A (en) * 2006-12-25 2008-07-10 Toshiba Corp Current lead, and superconducting device
JP2008251564A (en) * 2007-03-29 2008-10-16 Kyushu Univ High-temperature superconducting current lead and method for increasing critical current density
JP2010283186A (en) * 2009-06-05 2010-12-16 Hitachi Ltd Refrigerator-cooled superconducting magnet
CN102117691B (en) * 2010-01-05 2012-11-28 通用电气公司 Current lead wire system for superconducting magnet

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