JP4012736B2

JP4012736B2 - Current introduction terminal

Info

Publication number: JP4012736B2
Application number: JP2002010628A
Authority: JP
Inventors: 作太郎山口
Original assignee: YYL KK
Current assignee: YYL KK
Priority date: 2002-01-18
Filing date: 2002-01-18
Publication date: 2007-11-21
Anticipated expiration: 2022-01-18
Also published as: CA2397038A1; JP2003217735A; CA2397038C

Description

【０００１】
【発明の属する技術分野】
本発明は、電流導入端子に関し、特に電源と低温側の装置との接続に好適とされる電流導入端子に関する。
【０００２】
【従来の技術】
この種の電流導入端子（current terminal）としては、例えば図４に示すような構成が知られている。図４を参照すると、従来の電流導入端子において電極（２３Ａと２５Ａ、２３Ｂと２５Ｂ）が、例えばセラミックよりなるハウジング２２に収容されており、ハウジング２２には取りつけ用のフランジ２９が設けられており、フランジ２９に設けられた取り付け用の穴３０にネジ等で装置に固定される。図４には２芯の構成が示されているが、１芯構成としては、例えば図５に示すようなソケットコンタクト型のものが知られている。図４及び図５は、日立原町電子工業株式会社製の電流導入端子（製品名C102GL101、C201CK101）を模式的に示す図である。
【０００３】
【発明が解決しようとする課題】
かかる電流導入端子を、常温側の電源に接続される電極から低温側への電流供給に用いた場合、低温側への熱侵入が問題となる。
【０００４】
したがって、本発明が解決しようとする課題は、電源から電流を導入する電流導入端子において、熱侵入を抑止する端子を提供することにある。また本発明が解決しようとする課題は、熱放散を抑止する端子を提供することにある。
【０００５】
【課題を解決するための手段】
前記課題の少なくとも１つを解決するための手段を提供する本発明に係る電流導入端子は、一端の電極から導入された電流を、他端の電極から接続先に供給する導電部材の前記の一端と他端の間に、熱電変換素子を備えている。
【０００６】
本発明の一のアスペクトに係る電流導入端子は、第１の電極と、第２の電極を有し、前記第１の電極から電流を導入し、前記第１の電極から導入した電流を前記第２の電極より接続先に供給する電流導入端子において、前記第１の電極と前記第２の電極とが熱電変換素子を介して接続される。
【０００７】
本発明の他のアスペクトに係る電流導入端子は、第１の電極と、第２の電極を有し、前記第１の電極は、電源に接続され前記電源より電流を導入し、前記第１の電極から導入した電流を、前記第２の電極より電流供給先に供給し、第３の電極と、第４の電極を有し、前記第４の電極が、前記電流供給先から受けた電流を、前記第３の電極より、前記電源に返す構成とされている電流導入端子において、前記第１の電極と前記第２の電極とが、第１の導電型の熱電変換素子を介して接続され、前記第３の電極と前記第４の電極とが、第２の導電型の熱電変換素子を介して接続されている。
【０００８】
本発明において、前記第２の電極と、電流供給先機器との間に高温超伝導素子を備えるか、あるいは、前記第４の電極と、電流供給先機器との間に、高温超伝導素子を備えた構成としてもよい。
【０００９】
本発明においては、電極の間に挿入される前記熱電変換素子を複数段備えた構成としてもよい。
【００１０】
【発明の実施の形態】
本発明の実施の形態について説明する。本発明に係る電流導入端子は、その好ましい実施の形態において、図４又は図５に示した電流導入端子において、一端の電極から導入された電流を、他端の電極から接続先に供給する導電部材の、前記一端と他端の間に、熱電変換素子を配設したものである。より詳細には、図１を参照すると、第１の電極（３Ａ）から電流を導入し第２の電極（５Ａ）より第１の電極（３Ａ）から導入した電流を、電流供給先に対して供給する電流導入端子において、第１の電極（３Ａ）と第２の電極（５Ａ）との間に、第１の熱電変換素子（１Ａ）を備え、第１の電極（３Ａ）と第２の電極（５Ａ）とは第１の熱電変換素子（１Ａ）を介して電気的に接続される。２芯の場合には、上記構成の電極構造を２本備える。すなわち、第３の電極（３Ｂ）と第４の電極（５Ｂ）との間に第２の熱電変換素子（１Ｂ）を備え、第３の電極（３Ｂ）と第４の電極（５Ｂ）とが第２の熱電変換素子（１Ｂ）を介して電気的に接続される。
【００１１】
かかる本発明の実施の形態は、電流導入端子から低温系への熱侵入を熱電変換素子を用いて抑制するものである。例えば、図示されない直流電源の高位側電源端子（＋）を第１の電極（３Ａ）に接続し、直流電源の低位側電源端子（−）を第３の電極（３Ｂ）に接続し、第２の電極（５Ａ）と第４の電極（５Ｂ）に、電流供給先の機器（負荷）を接続すると、ペルチェ効果により、第１の熱電変換素子（１Ａ）では低温側から常温側への吸熱が行われ、第２の熱電変換素子（１Ｂ）では低温側からの熱の常温側への放熱が生じ、低温側の第２、第４の電極側が冷却される。電流の向きを逆向きに変えると、第１、第２の熱電変換素子（１Ａ、１Ｂ）で、低温側への熱の供給が行われる。熱電変換素子としては、好ましくは、熱電半導体素子が用いられる。
【００１２】
計測用の電流導入端子に接続するケーブルは、一例としての下記の仕様からなる。
【００１３】
長さ：１．５ｍ
径：１ φ
材質：銅
電流値：２Ａ（アンペア）
銅の熱伝導率は、常温で、３５０Ｗ／（ｍＫ）程度であり、低温になるにしたがい熱伝導率は高くなり、３０Ｋ程度で１２００Ｗ／（ｍＫ）までに上昇する。ちなみに、ＲＲＲが大きな値の銅であるほど、熱伝導率は高くなり、ＲＲＲ＝１０００で３０Ｋ程度で１２００Ｗ／（ｍＫ）、ＲＲＲ＝１０００では、１０、０００Ｗ／（ｍＫ）に達する。
【００１４】
本発明においては、好ましくは、図４等に示した電流導入端子の電極間に熱電半導体を接続して熱侵入を低減している。熱電半導体としては、例えばビスマス・テレル系（ＢｉＴｅ）を用いる。
【００１５】
長さ：５ｍｍ
太さ：１．８ｍｍ
材質：ビスマス・テレル系（ＢｉＴｅ）
電流値：２Ａ
ビスマス・テレル（ＢｉＴｅ）の熱伝導率は、常温（３００Ｋ）で１．５−０．９Ｗ／（ｍＫ）であり、２００Ｋでもあまり変化しない。そこで、熱伝導率はほぼ一定として扱ってもよい。これは、電気抵抗率の測定、Ｗｉｅｄｍａｎｎ−Ｆｒａｎｚ則によって、電子分の熱伝導率が求められ、フォノンの熱伝導率は通常の半導体の熱伝導率の温度依存性（κはＴの−０．５乗に比例）から、常温から低温までの半導体の熱伝導率の温度依存性が求められる。以下では、非通電時、通電時の熱侵入の見積もりを説明する。
【００１６】
熱抵抗（非通電時）：
銅ワイヤケーブル部分（電流リード）に、電流導入端子の熱電半導体（ビスマス・テレル）を接続した構成において、電流を流さないときの熱侵入の一例について説明する。熱伝導率を４００Ｗ／（ｍＫ）、１．２Ｗ／（ｍＫ）として熱計算する。
【００１７】
銅ワイヤケーブル部分（電流リード）の熱抵抗は、
Ｒ銅＝４．７７×１０^＋３Ｋ／Ｗ
ビスマス・テレル（ＢｉＴｅ）部分の熱抵抗は、
Ｒ_ＢｉＴｅ＝１．６４×１０^＋３Ｋ／Ｗ
１φの銅リード（電流リード）に対して、熱抵抗が３４％増大し、この分、熱侵入が低減する。
【００１８】
通電時の熱侵入：
銅ワイヤケーブル部分（電流リード）に、電流導入端子の熱電半導体（ビスマス・テレル）を接続した構成において、通電時の熱侵入の一例について説明する。通電時の熱侵入は、超伝導コイル等の電流リードの設計と同様に見積もることができる。なお、電流リードに、熱電半導体、高温超伝導体（ＨＴＳ）を組み込み、熱侵入が最小となるように最適化を施した計算例については、文献（K.Sato, H.Okumura, S.Yamaguchi, "Numerical calculation for Peltier current lead designing", Cryogenics, 41(2001) PP.497-503）の記載が参照される。
【００１９】
電流リードの単位電流あたりの熱侵入の計算結果の一例を、図２に示す。図２において、ＴＥは、熱電半導体を利用した場合であり、ＨＴＳは、高温超伝導体であり、Ｃｕは、銅リードを表している。なお、電流の単位はｋＡである。
【００２０】
また図２において、
Ｃｕは、銅で作成された電流リード、
Ｃｕ＋ＴＥは、銅と熱電半導体を組合せた電流リード、
Ｃｕ＋ＨＴＳは、銅リードと高温超伝導体を組合せた電流リード、
Ｃｕ＋ＨＴＳ＋ＴＥは、銅リードと高温超伝導体と熱電半導体を組合せた電流リードをそれぞれ表している。
【００２１】
極低温に配置される超伝導コイルと、常温側の電源端子とを接続する電流リードは、ガス冷却を用いて熱侵入を低減するシステムが採用される場合が多い。この場合、低温ガスとの熱交換率が熱侵入に大きな影響を与える。図２では、冷却ガスとの熱交換率ｆで表している。
【００２２】
計測用の電流リードでは、冷却用ガスが電流リードに沿って流れることはないので、冷却用ガスとの熱交換がない電流リード、すなわちｆ＝０として見積もってよい。なお、図２には、電流リードを構成するそれぞれの材料に対して、熱侵入を最小とするように最適化を施した結果が示されている。
【００２３】
計測用の電流リードについて、図２を着目すると、ＣｕとＣｕ＋ＴＥ（ｆ＝０．０）とが比較対象となり、ヘリウム（４．２Ｋ）に対して、Ｃｕでは、４３．５３、Ｃｕ＋ＴＥでは、３０．４３と、熱侵入はＣｕ＋ＴＥで３０％減少している。
【００２４】
また液体窒素（７７Ｋ）に対して、Ｃｕでは、４２．５１、Ｃｕ＋ＴＥでは、２７．８４と、熱侵入はＣｕ＋ＴＥで３５％減少している。
【００２５】
クライオスタット内部で用いられるＨＴＳとの組合せは、Ｃｕ＋ＨＴＳ＋ＴＥ構成で、熱侵入を低減している。ＨＴＳは、液体窒素ガスで冷却される電流リード（超伝導コイルと電流導入端子を接続するリード）の一部に挿入される。なお、低温側の電流リードに、ＨＴＳを挿入する構成については、特開平０８−１５３５４７号公報等が参照される。
【００２６】
電流リードをなす銅リードの常温端（電流導入端子に接続する端部）を３００Ｋ、低温側を４．２Ｋとした場合の熱侵入を最小化するために、１．５ｍの長さの電流リードに対して、０．８φの銅線（ＲＲＲ＝１００、ｆ＝０．０）が最適とされた断面とされる。このため、径１ φの電流リードは好ましいといえる。また、液体窒素（７７Ｋ）を利用する場合にも、径１φの電流リードが好ましい。
【００２７】
低温側への熱侵入について、まとめると、図３のようになる。電流値が２Ａ（アンペア）の通電であるため、図３（Ａ）の欄の数値を２倍すると、そのときの熱侵入が計算できる。通電時と、非通電時では、約２倍の熱侵入の違いがある。計測用の電流導入端子の場合、計測時以外、通常は通電しないため、熱電半導体によって熱侵入が低減する効果が大となる。
【００２８】
【実施例】
本発明を実施した電流導入端子の具体的な例について説明する。図１は、本発明の一実施例の電流導入端子の構成を示す図である。なお、図１には、二芯の構成が示されているが、単芯の構成にも適用できることは勿論である。
【００２９】
熱電半導体としてはＰ型とＮ型の２種の半導体が用いられる。単芯の構成において、電流導入端子の場合、Ｎ型の熱電半導体、電流を電源側に出力する端子の場合、Ｐ型の熱電半導体が用いられる。
【００３０】
図１において、１Ａ、１ＢはＮ型、Ｐ型熱電半導体であり、２は本体（ハウジング）、３Ａ、３Ｂは電流導入端子の常温側の電極、５Ａ、５Ｂは電流導入端子の低温側の電極である。６は支持部材（サポート）、７は絶縁体（電気的に絶縁、熱伝導体）、８はボルト、９は、電流導入端子取りつけ用のフランジであり、１０は、フランジ９をクライオスタット等（不図示）へ取りつけるためのボルト用の穴である。フランジ９は、空冷フィン又は水冷パイプ等の冷却手段を備え、放熱効果の増大を図るようにしてもよい。
【００３１】
電極５Ａ、５Ｂにゲーブルの一端を接続し、ケーブルの他端を低温側の機器（不図示）に接続する。また電極３Ａ、３Ｂには電源（不図示）の高位側電源端子と低位側電源端子（＋、−）にそれぞれ接続する。電流が常温側から低温側に導入される場合、電極３Ａには、Ｎ型熱電半導体１Ａを接続する。また低温側から常温側に電流が流れる場合、電極３Ｂには、Ｐ型熱電半導体１Ｂを接続する。かかる構成とすることで、低温側への熱侵入を低減する。逆に、電流が導入される電極３Ａに、Ｐ型熱電半導体１Ｂを接続し、電流が流れ出す電極３Ｂに、Ｎ型熱電半導体１Ｂを接続した場合（あるいは図１において電流の流れる向きを逆にした場合）、低温側の機器に熱が多く入るため、電源から電流導入端子を介して電流供給を受ける機器の昇温に有効である。
【００３２】
二つの熱電半導体１Ａ、１Ｂは、二芯の電極のそれぞれに設けられ、導電型（極性）が相違している。熱電半導体１Ａ、１Ｂは、電流２Ａ（アンペア）を流す場合、例えば長さ５ｍｍ、直径１．８ｍｍとされ、電極３Ａと５Ａの間、電極３Ｂと５Ｂの間に配設されている。熱電半導体１Ａ、１Ｂの両端は電気的なコンタクト部材１１Ａ、１２Ａと１１Ｂ、１２Ｂが設けられている。
【００３３】
熱電半導体１Ａ、１Ｂは、長さ５ｍｍにおいて、熱絶縁を行うものであり、運転条件によって変わるが、端部の温度差は、例えば５０℃〜１００℃程度になる。このため、電極低温側が、他の常温部分に接触しないような構成とされる。
【００３４】
電流導入端子において、常温側と、低温側と向き合う表面に、例えばアルミニウムをコーティングすることで、熱輻射を低減する構成としてもよい。アルミニウム板（熱輻射板）をハウジング２内の常温側と低温側の間に設け、電極（３Ａ、３Ｂ、５Ａ、５Ｂ）と電気的に絶縁させて設けてもよい。
【００３５】
また熱電半導体１Ａ、１Ｂは、電極３Ａ、３Ｂ、電極５Ａ、５Ｂに半田付け等で接続するため、接続部分に応力が加わって接続不良とならないように支持される。図１に示す例では、ハウジング２、フランジ９に対して支持ボルト６で固定されるサポート８に設けられた穴に、電極５Ａ、５Ｂが挿通されて支持されている。支持ボルト６としては例えばステンレス、サポート８は、ガラス材等、いずれも、熱伝導率が低く、且つ電気的絶縁部材が用いられる。
【００３６】
常温側に露出する電極３Ｂは、熱電半導体１Ｂによって低温側から熱が運びこまれるため、好ましくは、熱放散を考慮した構造とする。例えば棒状の電極３には、その外周を覆って、電極３Ａ、３Ｂよりも大きな径の電極４Ａ、４Ｂが取り付けられており、熱容量を大きくしている。そして、電極４Ａ、４Ｂは、電極３Ａ、３Ｂより電極４Ａ、４Ｂに伝達された熱をハウジング２に伝え、さらにフランジ９に容易に伝達する構成とされる。
【００３７】
常温側電極（３Ａ、３Ｂ）と低温側電極（５Ａ、５Ｂ）は電気的に絶縁されるため、互いに電気的絶縁物を介して接合され、本体（ハウジング）２（後述するようにアルミよりなる）と間にも、電気的絶縁層７が介在している。この電気的絶縁層７は、ベリリア、窒化アルミニウム等の熱伝導率の良好なセラミック材よりなり、できるだけ薄く設けられている。
【００３８】
フランジ９は、通常はステンレス製とされるが、この実施例では、熱放散を考慮して、熱伝導率の良好なアルミニウムよりなる。あるいは、電気的な絶縁を図る構成として上で、フランジ９は銅で構成してもよい。
【００３９】
上記のような構成により、電流の向きと、熱電半導体との組み合わせにより、熱を常温側に放散させ（冷却作用）、低温側への熱進入を抑制する電流導入端子を実現できた。
【００４０】
また図１において、電流を流す方向を反対とすることで、低温側へ通常よりも多くの熱を運ぶことができ、昇温時間を短縮することができる。
【００４１】
なお、図１では示されていないが、図１の電流導入端子の低温側を、電流リードを介して、超伝導コイルに接続する場合、低温側の電流リードの一部を、高温超伝導体（ＨＴＳ）で構成してもよい。
【００４２】
また図１では、二芯構成の電流導入端子の構成を例に本発明を説明したが、１芯の電極の構成も、同様にして構成される。すなわち、図１において、１対の常温側電極３Ａ、３Ｂと、一対の低温側電極５Ａ、５Ｂの代わりに、一つの常温側電極３Ａと一つの低温側電極５Ａの一芯構造とし、その間に熱電半導体１Ａを備えて構成される。あるいは、一つの常温側電極３Ｂと一つの低温側電極５Ｂで構成し、その間に熱電半導体１Ｂを備えて構成される。フランジ９、サポート８、ボルト６、絶縁物７等は、図１に示した構成と同様とされる。
【００４３】
本発明は、２芯に限定されず、さらに多芯の電極の電流導入端子にも適用可能である。また、熱電半導体はビスマス・テレル系にのみ限定されるものではない。
【００４４】
図６は、本発明の一実施例の変形例を示す図であり、図１（Ｂ）の断面図をよりわかりやすく示すとともに、熱の伝達経路を模式的に示したものである。図６において、電極４Ａ、４Ｂのコンタクト表面側には、セラミクス材料等の絶縁層１５が設けられている。この部在の室温側表面には反射膜をコーティングしてもよい。棒状の電極３Ａ、３Ｂの各一端が、電極３Ａ、３Ｂよりも大きな径の電極４Ａ、４Ｂに接続されており、熱容量を大きくしている。そして、電極４Ａ、４Ｂは、電極３Ａ、３Ｂより電極４Ａ、４Ｂに伝達された熱を、電気的絶縁層７を介してハウジング２に伝え、さらにフランジ９に容易に伝達する構成とされる。すなわち、図６に矢線で示す方向に熱が放散される。
【００４５】
棒状の電極５Ａ、５Ｂの各一端は、支持ボルト６でハウジング２及びフランジ９に固定されるサポート８に設けられた穴に挿通されて支持されている。電極３Ａ、３Ｂは、より大きな径の電極４Ａ、４Ｂを介して熱電半導体１Ａ、１Ｂに接続されており、電極４Ａ、４Ｂは、電極３Ａ、３Ｂより電極４Ａ、４Ｂに伝達された熱をハウジング２に伝え、さらにフランジ９に容易に伝達する構成とされる。図１及び図６の構成において、電流導入端子は真空を保つシール構造（ハーメチックシール構造）とされている。
【００４６】
図７は、本発明のさらに別の実施例の構成を示す図である。この実施例では、熱電半導体を複数段接続して構成したものであり、放熱効果、あるいは発熱効果を高めている。図７を参照すると、常温側と低温側の二つの電極（第１、第２の電極）との間に、複数段（図では２段）のＰ型の熱電変換素子（Ｐ）が配設されており、複数段の第１の導電型の熱電変換素子の端部の熱電変換素子（Ｐ）が低温側の電極に接続されており、さらに、Ｎ型の熱電変換素子（Ｎ）と、別のＰ型の熱電変換素子（Ｐ）と、を備えて第１群の（計４つ）熱電変換素子を構成しており（図７の右側）、複数段のＰ型の熱電変換素子のうちの常温側の端部にある1つの熱電変換素子（Ｐ）とＮ型の熱電変換素子（Ｎ）とを銅電極でπ型に接続して第１の熱電素子対を構成し、第１の熱電素子対を構成するＮ型の熱電変換素子（Ｎ）と別のＰ型の熱電変換素子（Ｐ）とを銅電極でπ型に接続して第２の熱電素子対を構成し、第２の熱電素子対のＰ型の熱電変換素子（Ｐ）のπ接続用の銅電極とは反対側の銅電極が、電源側の電極に接続されている。
【００４７】
さらに常温側と低温側の二つの電極（第３、第４の電極）との間に、複数段（２段）のＮ型の熱電変換素子（Ｎ）が配設されており、複数段のＮ型の熱電変換素子の端部の熱電変換素子（Ｎ）が低温側の電極に接続されており、さらに、Ｐ型の熱電変換素子（Ｐ）と、別のＮ型の熱電変換素子（Ｎ）と、を備えて第２群の（計４つ）熱電変換素子を構成しており（図７の左側）、複数段のＮ型の熱電変換素子のうちの常温側の端部にある1つの熱電変換素子（Ｎ）とＰ型の熱電変換素子（Ｐ）とを銅電極でπ型に接続して第３の熱電素子対を構成し、第３の熱電素子対を構成するＰ型の熱電変換素子（Ｐ）と別のＮ型の熱電変換素子（Ｎ）とを銅電極でπ型に接続して第４の熱電素子対を構成し、第４の熱電素子対のＮ型の熱電変換素子（Ｎ）のπ接続用の銅電極とは反対側の銅電極が、電源側（常温側）の電極に接続されている。第１、第３の熱電素子対の銅電極の表面、第２、第４の熱電素子対の銅電極の表面は、第１、第２のプレート（ＡｌＮＰｌａｔｅ−１、ＡｌＮＰｌａｔｅ−２）で覆われており、電気的に絶縁されている。窒化アルミニウム（ＡｌＮ）は高い電気的絶縁性と熱導電率を有し、ヒートシンクとしての用途を有する。
【００４８】
以上本発明を上記実施例に即して説明したが、本発明は、上記実施例にのみ限定されるものでなく、特許請求の範囲の各請求項の発明の範囲内で当業者であればなし得るであろう各種変形、修正を含むことは勿論である。
【００４９】
【発明の効果】
以上説明したように、本発明によれば、熱電半導体を備えたことにより、低温側への熱進入を抑制するとともに、熱を常温側に放散させる、電流導入端子を実現することができる。
【００５０】
また、本発明によれば、電流を流す方向を反対とすることで、低温側へ通常よりも多くの熱を運ぶことができ、昇温時間を短縮することができる。
【図面の簡単な説明】
【図１】本発明の一実施例の構成を示す図であり、（Ａ）は上面図、（Ｂ）は横断面図である。
【図２】本発明の原理を説明するための図である。
【図３】本発明の原理を説明するための図である。
【図４】従来の電流導入端子の例を示す図である。
【図５】従来の電流導入端子の例を示す図である。
【図６】本発明の一実施例の変形例の構成を示す図である。
【図７】本発明の別の実施例の構成を示す図である。
【符号の説明】
１Ａ、１Ｂ熱電半導体
２本体（ハウジング）
３Ａ、３Ｂ電極（常温側電極）
４Ａ、４Ｂ電極
５Ａ、５Ｂ電極（低温側電極）
６支持ボルト
７絶縁物
８電気絶縁サポート
９フランジ
１０取り付け穴
１１、１２コンタクト部材
１５絶縁部材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a current introduction terminal, and more particularly, to a current introduction terminal suitable for connection between a power source and a low-temperature device.
[0002]
[Prior art]
As this type of current introduction terminal (current terminal), for example, a configuration as shown in FIG. 4 is known. Referring to FIG. 4, electrodes (23A and 25A, 23B and 25B) in a conventional current introduction terminal are accommodated in a housing 22 made of, for example, ceramic, and the housing 22 is provided with a flange 29 for mounting. , And are fixed to the apparatus with screws or the like in mounting holes 30 provided in the flange 29. FIG. 4 shows a two-core configuration. As the one-core configuration, for example, a socket contact type as shown in FIG. 5 is known. 4 and 5 are diagrams schematically showing current introduction terminals (product names C102GL101 and C201CK101) manufactured by Hitachi Haramachi Electronics Co., Ltd. FIG.
[0003]
[Problems to be solved by the invention]
When such a current introduction terminal is used to supply current from the electrode connected to the power supply on the normal temperature side to the low temperature side, heat penetration into the low temperature side becomes a problem.
[0004]
Therefore, the problem to be solved by the present invention is to provide a terminal for suppressing heat intrusion in a current introduction terminal for introducing current from a power source. Another object of the present invention is to provide a terminal that suppresses heat dissipation.
[0005]
[Means for Solving the Problems]
The current introduction terminal according to the present invention, which provides means for solving at least one of the above problems, is characterized in that the one end of the conductive member that supplies the current introduced from the electrode at one end to the connection destination from the electrode at the other end. And a thermoelectric conversion element between the other end.
[0006]
A current introduction terminal according to an aspect of the present invention includes a first electrode and a second electrode, and introduces a current from the first electrode, and introduces the current introduced from the first electrode to the first electrode. In the current introduction terminal supplied from the two electrodes to the connection destination, the first electrode and the second electrode are connected via a thermoelectric conversion element.
[0007]
A current introduction terminal according to another aspect of the present invention includes a first electrode and a second electrode, and the first electrode is connected to a power source and introduces a current from the power source. The current introduced from the electrode is supplied from the second electrode to the current supply destination, and has a third electrode and a fourth electrode, and the fourth electrode receives the current received from the current supply destination. In the current introduction terminal configured to return to the power source from the third electrode, the first electrode and the second electrode are connected via a thermoelectric conversion element of the first conductivity type. The third electrode and the fourth electrode are connected via a thermoelectric conversion element of the second conductivity type.
[0008]
In the present invention, a high temperature superconducting element is provided between the second electrode and the current supply destination device, or a high temperature superconducting element is provided between the fourth electrode and the current supply destination device. It is good also as a structure provided.
[0009]
In the present invention, the thermoelectric conversion element inserted between the electrodes may have a plurality of stages.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described. In a preferred embodiment of the current introduction terminal according to the present invention, the current introduction terminal shown in FIG. 4 or 5 is a conductive material for supplying the current introduced from the electrode at one end to the connection destination from the electrode at the other end. A thermoelectric conversion element is disposed between the one end and the other end of the member. More specifically, referring to FIG. 1, the current introduced from the first electrode (3A) and introduced from the first electrode (3A) from the second electrode (5A) is supplied to the current supply destination. In the current introduction terminal to be supplied, the first thermoelectric conversion element (1A) is provided between the first electrode (3A) and the second electrode (5A), and the first electrode (3A) and the second electrode The electrode (5A) is electrically connected via the first thermoelectric conversion element (1A). In the case of two cores, two electrode structures having the above configuration are provided. That is, the second thermoelectric conversion element (1B) is provided between the third electrode (3B) and the fourth electrode (5B), and the third electrode (3B) and the fourth electrode (5B) are It is electrically connected through the second thermoelectric conversion element (1B).
[0011]
In the embodiment of the present invention, heat penetration from the current introduction terminal to the low temperature system is suppressed using a thermoelectric conversion element. For example, a high-order power supply terminal (+) of a DC power supply (not shown) is connected to the first electrode (3A), a low-order power supply terminal (−) of the DC power supply is connected to the third electrode (3B), and the second When the current supply device (load) is connected to the electrode (5A) and the fourth electrode (5B), the first thermoelectric conversion element (1A) absorbs heat from the low temperature side to the normal temperature side due to the Peltier effect. In the second thermoelectric conversion element (1B), heat from the low temperature side is released to the normal temperature side, and the second and fourth electrode sides on the low temperature side are cooled. When the direction of the current is changed to the opposite direction, the first and second thermoelectric conversion elements (1A, 1B) supply heat to the low temperature side. A thermoelectric semiconductor element is preferably used as the thermoelectric conversion element.
[0012]
The cable connected to the current introduction terminal for measurement has the following specifications as an example.
[0013]
Length: 1.5m
Diameter: 1 φ
Material: Copper current value: 2A (Ampere)
The thermal conductivity of copper is about 350 W / (mK) at room temperature, and the thermal conductivity increases as the temperature decreases, and increases to 1200 W / (mK) at about 30K. Incidentally, the higher the RRR, the higher the thermal conductivity, and the higher the thermal conductivity, the higher the RRR = 1000, the power reaches 1200 W / (mK) at about 30K, and the RRR = 1000 reaches 10,000 W / (mK).
[0014]
In the present invention, preferably, a thermoelectric semiconductor is connected between the electrodes of the current introduction terminal shown in FIG. As the thermoelectric semiconductor, for example, a bismuth-telell system (BiTe) is used.
[0015]
Length: 5mm
Thickness: 1.8mm
Material: Bismuth / Terrel (BiTe)
Current value: 2A
The thermal conductivity of bismuth tellurium (BiTe) is 1.5-0.9 W / (mK) at room temperature (300K), and does not change much even at 200K. Therefore, the thermal conductivity may be treated as being almost constant. This is because the thermal conductivity of electrons is determined by the measurement of electrical resistivity and the Wiedmann-Franz rule, and the thermal conductivity of phonons depends on the temperature dependence of the thermal conductivity of ordinary semiconductors (κ is −0. (Proportional to the fifth power), the temperature dependence of the thermal conductivity of the semiconductor from room temperature to low temperature is required. Below, the estimation of the heat penetration at the time of non-energization and at the time of electricity supply is demonstrated.
[0016]
Thermal resistance (when not energized):
An example of heat intrusion when no current is passed in a configuration in which a thermoelectric semiconductor (bismuth-telell) as a current introduction terminal is connected to a copper wire cable portion (current lead) will be described. Thermal calculation is performed assuming that the thermal conductivity is 400 W / (mK) and 1.2 W / (mK).
[0017]
The thermal resistance of the copper wire cable part (current lead) is
R copper = 4.77 × 10 ⁺³ K / W
The thermal resistance of the bismuth-telell (BiTe) part is
R _BiTe = 1.64 × 10 ⁺³ K / W
The thermal resistance is increased by 34% with respect to a 1φ copper lead (current lead), and the heat penetration is reduced by this amount.
[0018]
Heat penetration during energization:
An example of heat penetration during energization will be described in a configuration in which a thermoelectric semiconductor (bismuth / terer) as a current introduction terminal is connected to a copper wire cable portion (current lead). Heat penetration during energization can be estimated in the same manner as the design of current leads such as superconducting coils. For calculation examples that incorporate thermoelectric semiconductors and high-temperature superconductors (HTS) into the current leads and have been optimized to minimize heat intrusion, see the literature (K.Sato, H.Okumura, S.Yamaguchi , "Numerical calculation for Peltier current lead designing", Cryogenics, 41 (2001) PP.497-503).
[0019]
An example of the calculation result of the heat penetration per unit current of the current lead is shown in FIG. In FIG. 2, TE represents a case where a thermoelectric semiconductor is used, HTS represents a high-temperature superconductor, and Cu represents a copper lead. The unit of current is kA.
[0020]
Also in FIG.
Cu is a current lead made of copper,
Cu + TE is a current lead that combines copper and a thermoelectric semiconductor,
Cu + HTS is a current lead that combines a copper lead and a high-temperature superconductor.
Cu + HTS + TE represents a current lead in which a copper lead, a high-temperature superconductor, and a thermoelectric semiconductor are combined.
[0021]
In many cases, a current lead that connects a superconducting coil arranged at a cryogenic temperature and a power supply terminal on the room temperature side employs a system that reduces heat penetration using gas cooling. In this case, the heat exchange rate with the low temperature gas has a great influence on the heat penetration. In FIG. 2, it represents with the heat exchange rate f with cooling gas.
[0022]
In the measurement current lead, since the cooling gas does not flow along the current lead, it may be estimated that the current lead does not exchange heat with the cooling gas, that is, f = 0. FIG. 2 shows the result of optimization for each material constituting the current lead to minimize heat penetration.
[0023]
With regard to the current lead for measurement, focusing on FIG. 2, Cu and Cu + TE (f = 0.0) are to be compared, and compared to helium (4.2K), Cu is 43.53, and Cu + TE is 30. .43, the heat penetration is reduced by 30% with Cu + TE.
[0024]
In addition, with respect to liquid nitrogen (77K), heat penetration is reduced by 35% for Cu + TE, with 42.51 for Cu and 27.84 for Cu + TE.
[0025]
The combination with the HTS used inside the cryostat is a Cu + HTS + TE configuration, reducing heat penetration. The HTS is inserted into a part of a current lead (a lead connecting the superconducting coil and the current introduction terminal) cooled by liquid nitrogen gas. For a configuration in which an HTS is inserted into a low-temperature current lead, refer to Japanese Patent Application Laid-Open No. 08-153547.
[0026]
In order to minimize heat intrusion when the normal temperature end (the end connected to the current introduction terminal) of the copper lead forming the current lead is 300K and the low temperature side is 4.2K, a 1.5m long current lead On the other hand, a 0.8φ copper wire (RRR = 100, f = 0.0) is the optimum cross section. For this reason, it can be said that a current lead having a diameter of 1φ is preferable. Also, when using liquid nitrogen (77K), a current lead having a diameter of 1φ is preferable.
[0027]
The heat penetration to the low temperature side is summarized as shown in FIG. Since the current value is energization of 2 A (ampere), the heat penetration at that time can be calculated by doubling the numerical value in the column of FIG. There is a difference of about twice as much heat penetration between energized and non-energized. In the case of a current introduction terminal for measurement, since current is not normally supplied except during measurement, the effect of reducing heat penetration by the thermoelectric semiconductor is great.
[0028]
【Example】
A specific example of the current introduction terminal embodying the present invention will be described. FIG. 1 is a diagram showing a configuration of a current introduction terminal according to an embodiment of the present invention. Although FIG. 1 shows a two-core configuration, it is of course applicable to a single-core configuration.
[0029]
Two types of semiconductors, P-type and N-type, are used as thermoelectric semiconductors. In a single-core configuration, an N-type thermoelectric semiconductor is used in the case of a current introduction terminal, and a P-type thermoelectric semiconductor is used in the case of a terminal that outputs current to the power supply side.
[0030]
In FIG. 1, 1A and 1B are N-type and P-type thermoelectric semiconductors, 2 is a main body (housing), 3A and 3B are electrodes on the normal temperature side of the current introduction terminal, and 5A and 5B are electrodes on the low temperature side of the current introduction terminal. It is. 6 is a support member (support), 7 is an insulator (electrically insulated, heat conductor), 8 is a bolt, 9 is a flange for attaching a current introduction terminal, 10 is a flange such as a cryostat, etc. It is a hole for a bolt for attaching to the figure. The flange 9 may be provided with cooling means such as air-cooled fins or water-cooled pipes to increase the heat dissipation effect.
[0031]
One end of the gable is connected to the electrodes 5A and 5B, and the other end of the cable is connected to a low-temperature device (not shown). The electrodes 3A and 3B are respectively connected to a high-order power supply terminal and a low-order power supply terminal (+, −) of a power supply (not shown). When the current is introduced from the normal temperature side to the low temperature side, the N-type thermoelectric semiconductor 1A is connected to the electrode 3A. When current flows from the low temperature side to the normal temperature side, the P-type thermoelectric semiconductor 1B is connected to the electrode 3B. By adopting such a configuration, heat intrusion to the low temperature side is reduced. On the contrary, when the P-type thermoelectric semiconductor 1B is connected to the electrode 3A into which the current is introduced and the N-type thermoelectric semiconductor 1B is connected to the electrode 3B from which the current flows (or the direction in which the current flows is reversed in FIG. 1). In this case, a large amount of heat enters the low temperature side device, which is effective for increasing the temperature of the device that receives current supply from the power source through the current introduction terminal.
[0032]
The two thermoelectric semiconductors 1A and 1B are provided on each of the two-core electrodes and have different conductivity types (polarities). The thermoelectric semiconductors 1A and 1B have, for example, a length of 5 mm and a diameter of 1.8 mm when a current 2A (ampere) flows, and are disposed between the electrodes 3A and 5A and between the electrodes 3B and 5B. Electrical contact members 11A, 12A and 11B, 12B are provided at both ends of the thermoelectric semiconductors 1A, 1B.
[0033]
The thermoelectric semiconductors 1A and 1B perform thermal insulation at a length of 5 mm, and vary depending on operating conditions, but the temperature difference at the end is, for example, about 50 ° C to 100 ° C. For this reason, it is set as the structure where an electrode low temperature side does not contact another normal temperature part.
[0034]
In the current introduction terminal, the surface facing the normal temperature side and the low temperature side may be coated with, for example, aluminum to reduce heat radiation. An aluminum plate (thermal radiation plate) may be provided between the room temperature side and the low temperature side in the housing 2 and electrically insulated from the electrodes (3A, 3B, 5A, 5B).
[0035]
In addition, since the thermoelectric semiconductors 1A and 1B are connected to the electrodes 3A and 3B and the electrodes 5A and 5B by soldering or the like, the thermoelectric semiconductors 1A and 1B are supported so that stress is not applied to the connection portion and connection failure does not occur. In the example shown in FIG. 1, electrodes 5 </ b> A and 5 </ b> B are inserted and supported in holes provided in a support 8 that is fixed to the housing 2 and the flange 9 with support bolts 6. As the support bolt 6, for example, stainless steel and the support 8 are made of a glass material or the like, both of which have low thermal conductivity and an electrically insulating member is used.
[0036]
The electrode 3B exposed to the normal temperature side preferably has a structure in consideration of heat dissipation since heat is carried from the low temperature side by the thermoelectric semiconductor 1B. For example, the rod-like electrode 3 is provided with electrodes 4A and 4B having a diameter larger than that of the electrodes 3A and 3B so as to cover the outer periphery thereof, thereby increasing the heat capacity. The electrodes 4A and 4B are configured to transmit the heat transmitted from the electrodes 3A and 3B to the electrodes 4A and 4B to the housing 2 and further to the flange 9 easily.
[0037]
Since the normal temperature side electrodes (3A, 3B) and the low temperature side electrodes (5A, 5B) are electrically insulated, they are joined to each other via an electrical insulator, and are made of a main body (housing) 2 (made of aluminum as will be described later). ) And an electrical insulating layer 7 are also interposed. The electrical insulating layer 7 is made of a ceramic material having a good thermal conductivity such as beryllia or aluminum nitride and is provided as thin as possible.
[0038]
The flange 9 is usually made of stainless steel, but in this embodiment, it is made of aluminum having good thermal conductivity in consideration of heat dissipation. Alternatively, the flange 9 may be made of copper in order to achieve electrical insulation.
[0039]
With the configuration as described above, a current introduction terminal capable of dissipating heat to the normal temperature side (cooling action) and suppressing heat entry to the low temperature side can be realized by combining the direction of current and the thermoelectric semiconductor.
[0040]
Further, in FIG. 1, by reversing the direction in which the current flows, more heat than usual can be carried to the low temperature side, and the temperature raising time can be shortened.
[0041]
Although not shown in FIG. 1, when the low temperature side of the current introduction terminal in FIG. 1 is connected to the superconducting coil via the current lead, a part of the low temperature side current lead is connected to the high temperature superconductor. (HTS) may be used.
[0042]
In FIG. 1, the present invention has been described by taking the configuration of a current introduction terminal having a two-core configuration as an example, but the configuration of a one-core electrode is configured in the same manner. That is, in FIG. 1, instead of the pair of room temperature side electrodes 3A and 3B and the pair of low temperature side electrodes 5A and 5B, a single core structure of one room temperature side electrode 3A and one low temperature side electrode 5A is provided. A thermoelectric semiconductor 1A is provided. Alternatively, it is configured by one normal temperature side electrode 3B and one low temperature side electrode 5B, and includes a thermoelectric semiconductor 1B therebetween. The flange 9, the support 8, the bolt 6, the insulator 7 and the like are the same as those shown in FIG.
[0043]
The present invention is not limited to two cores, and can also be applied to current introduction terminals of multi-core electrodes. Further, the thermoelectric semiconductor is not limited to the bismuth / tellurium system.
[0044]
FIG. 6 is a view showing a modification of one embodiment of the present invention, showing the cross-sectional view of FIG. 1 (B) in an easy-to-understand manner and schematically showing a heat transfer path. In FIG. 6, an insulating layer 15 made of a ceramic material or the like is provided on the contact surface side of the electrodes 4A and 4B. A reflective film may be coated on the room temperature side surface of this part. One end of each of the rod-shaped electrodes 3A and 3B is connected to electrodes 4A and 4B having a diameter larger than that of the electrodes 3A and 3B, thereby increasing the heat capacity. The electrodes 4A and 4B are configured to transmit the heat transmitted from the electrodes 3A and 3B to the electrodes 4A and 4B to the housing 2 via the electrical insulating layer 7 and further to the flange 9 easily. That is, heat is dissipated in the direction indicated by the arrow in FIG.
[0045]
One end of each of the rod-shaped electrodes 5A and 5B is inserted into and supported by a hole provided in a support 8 fixed to the housing 2 and the flange 9 by a support bolt 6. The electrodes 3A and 3B are connected to the thermoelectric semiconductors 1A and 1B via the electrodes 4A and 4B having larger diameters. The electrodes 4A and 4B housing the heat transferred from the electrodes 3A and 3B to the electrodes 4A and 4B. 2 and further easily transmitted to the flange 9. 1 and 6, the current introduction terminal has a seal structure (hermetic seal structure) that maintains a vacuum.
[0046]
FIG. 7 is a diagram showing the configuration of still another embodiment of the present invention. In this embodiment, a plurality of thermoelectric semiconductors are connected, and the heat dissipation effect or heat generation effect is enhanced. Referring to FIG. 7, a plurality of (two stages in the figure) P-type thermoelectric conversion elements (P) are arranged between two electrodes (first and second electrodes) on the normal temperature side and the low temperature side. The thermoelectric conversion elements (P) at the ends of the first-stage thermoelectric conversion elements of the plurality of stages are connected to the low temperature side electrode, and further, an N-type thermoelectric conversion element (N), Another P-type thermoelectric conversion element (P), and constitutes a first group (four total) of thermoelectric conversion elements (on the right side of FIG. 7). One thermoelectric conversion element (P) and an N-type thermoelectric conversion element (N) at the end of the room temperature side are connected in a π-type with a copper electrode to form a first thermoelectric element pair, An N-type thermoelectric conversion element (N) constituting another thermoelectric element pair and another P-type thermoelectric conversion element (P) are connected in a π-type with a copper electrode to form a second thermoelectric element pair, 2 thermoelectric element pairs The copper electrode for π connection of the P-type thermoelectric conversion element (P) Copper electrode of opposite side is connected to the electrode of the power source side.
[0047]
Further, a plurality of stages (two stages) of N-type thermoelectric conversion elements (N) are disposed between the normal temperature side and the low temperature side electrodes (third and fourth electrodes). The thermoelectric conversion element (N) at the end of the N-type thermoelectric conversion element is connected to the low temperature side electrode, and further, the P-type thermoelectric conversion element (P) and another N-type thermoelectric conversion element (N ) And the second group (four total) of thermoelectric conversion elements (left side in FIG. 7), and is located at the end of the room temperature side of the N-stage thermoelectric conversion elements in a plurality of stages. Two thermoelectric conversion elements (N) and a P-type thermoelectric conversion element (P) are connected in a π-type with a copper electrode to form a third thermoelectric element pair, and a P-type element constituting the third thermoelectric element pair The thermoelectric conversion element (P) and another N-type thermoelectric conversion element (N) are connected in a π-type with a copper electrode to form a fourth thermoelectric element pair, and the N-type thermoelectric of the fourth thermoelectric element pair Conversion element (N) The copper electrode for π connection copper electrode on the opposite side is connected to the electrode of the power supply side (cold side). The surfaces of the copper electrodes of the first and third thermoelectric element pairs and the surfaces of the copper electrodes of the second and fourth thermoelectric element pairs are the first and second plates (AlN Plate-1, AlN Plate-2). Covered and electrically insulated. Aluminum nitride (AlN) has high electrical insulation and thermal conductivity, and has use as a heat sink.
[0048]
The present invention has been described with reference to the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and those skilled in the art are within the scope of the invention of each claim. Needless to say, various modifications and corrections may be obtained.
[0049]
【The invention's effect】
As described above, according to the present invention, by providing the thermoelectric semiconductor, it is possible to realize a current introduction terminal that suppresses heat entry to the low temperature side and dissipates heat to the normal temperature side.
[0050]
Further, according to the present invention, by reversing the direction in which the current flows, more heat than usual can be carried to the low temperature side, and the temperature raising time can be shortened.
[Brief description of the drawings]
1A and 1B are diagrams showing a configuration of an embodiment of the present invention, in which FIG. 1A is a top view and FIG. 1B is a cross-sectional view.
FIG. 2 is a diagram for explaining the principle of the present invention.
FIG. 3 is a diagram for explaining the principle of the present invention.
FIG. 4 is a diagram illustrating an example of a conventional current introduction terminal.
FIG. 5 is a diagram illustrating an example of a conventional current introduction terminal.
FIG. 6 is a diagram showing a configuration of a modification of one embodiment of the present invention.
FIG. 7 is a diagram showing the configuration of another embodiment of the present invention.
[Explanation of symbols]
1A, 1B Thermoelectric semiconductor 2 Body (housing)
3A, 3B electrode (room temperature side electrode)
4A, 4B electrode 5A, 5B electrode (low temperature side electrode)
6 Support bolt 7 Insulator 8 Electrical insulation support 9 Flange 10 Mounting hole 11, 12 Contact member 15 Insulation member

Claims

A current introduction terminal which has a first electrode and a second electrode, introduces a current from the first electrode, and supplies a current introduced from the first electrode to a connection destination from the second electrode; ,
The first electrode and the second electrode are connected via a thermoelectric conversion element ,
The first electrode and the second electrode are both made of rod-shaped members,
A housing for housing at least a part of each of the first electrode and the second electrode in the longitudinal direction;
The first electrode and / or the second electrode is supported in the housing via a support member,
The ends of the first electrode and the second electrode are connected to each other via the thermoelectric conversion element,
The current introduction terminal, wherein the first electrode is configured to have greater heat dissipation characteristics than the second electrode, and conducts heat to the housing on a room temperature side .

The first electrode has a first electrode and a second electrode, and the first electrode is connected to a power source and introduces a current from the power source. The current introduced from the first electrode is obtained from the second electrode. Supply to the current supply destination,
A current introduction terminal having a third electrode and a fourth electrode, wherein the fourth electrode returns the current received from the current supply destination to the power source from the third electrode. In
The first electrode and the second electrode are connected via a thermoelectric conversion element of a first conductivity type,
The third electrode and the fourth electrode are connected via a thermoelectric conversion element of a second conductivity type ,
The first electrode and the second electrode are both made of rod-shaped members,
A housing for housing at least a part of each of the first electrode and the second electrode in the longitudinal direction;
The first electrode and / or the second electrode is supported in the housing via a support member,
The ends of the first electrode and the second electrode are connected to each other via the thermoelectric conversion element ,
The current introduction terminal, wherein the first electrode is configured to have greater heat dissipation characteristics than the second electrode, and conducts heat to the housing on a room temperature side .

The first electrode has a first electrode and a second electrode, and the first electrode is connected to a power source and introduces a current from the power source. The current introduced from the first electrode is obtained from the second electrode. Supply to the current supply destination,
A current introduction terminal having a third electrode and a fourth electrode, wherein the fourth electrode returns the current received from the current supply destination to the power source from the third electrode. In
The first electrode and the second electrode are connected via a thermoelectric conversion element of a first conductivity type,
The third electrode and the fourth electrode are connected via a thermoelectric conversion element of a second conductivity type,
The third electrode and the fourth electrode are both made of rod-shaped members,
A housing for housing at least a part of each of the first electrode and the second electrode in the longitudinal direction;
The third electrode and / or the fourth electrode is supported through a support member in the housing,
The ends of the third electrode and the fourth electrode are connected via a thermoelectric conversion element,
The current introduction terminal, wherein the first electrode is configured to have greater heat dissipation characteristics than the second electrode, and conducts heat to the housing on a room temperature side .

The first electrode is a part of the longitudinal direction, and is connected to an electrode having a larger diameter than the first electrode in order to increase the heat capacity in the housing.
Larger electrode of the diameter, according to the housing of the room temperature side, heat through the member of conduction to and electrically insulating material is connected, it in any one of claims 1 to 3, wherein Current introduction terminal.

The current introduction terminal according to claim 4 , wherein an insulating layer is provided on a connector-side surface of the electrode having a large diameter.

The current introduction terminal according to claim 5 , wherein the insulating layer is made of a ceramic material.

The third electrode, the fourth electrode and compared with heat dissipation characteristics are to become large structure, transferring heat to the housing of the room temperature side, according to claim 3, wherein the cable terminal, characterized in that.

The third electrode is a part of the longitudinal direction, and is connected to an electrode having a larger diameter than the third electrode in order to increase heat capacity in the housing.
4. The current introduction terminal according to claim 3, wherein the large-diameter electrode is connected to the housing on the room temperature side through an insulating member that conducts heat and is electrically connected.

In cable terminal according to any one of claims 1 to 8, having a sealing structure to keep the vacuum current and wherein the feedthrough.

Wherein the housing, cable terminal according to any one of claims 1 to 8 flange for mounting is provided, it is characterized.

The current introducing terminal according to claim 10 , wherein the flange includes cooling means.

The current introduction terminal according to claim 11, wherein the cooling means is an air cooling fin or a water cooling pipe.

The current introduction terminal according to claim 10, wherein the member constituting the flange is made of aluminum or copper.

Wherein the second electrode, made of copper, the current introduction terminal according to any one of claims 1 to 3, characterized in that.

The current introduction terminal according to claim 2 , wherein the fourth electrode is made of copper.

Said first electrode is arranged on the room temperature side, the second electrode is disposed on the low temperature side, the surface facing the room-temperature side and low temperature side, the metal is Kotin grayed, reduces heat radiation, characterized The current introduction terminal according to any one of claims 1 to 3 .

The third electrode is disposed on the room temperature side, the fourth electrode is disposed on the low temperature side, the surface facing the room-temperature side and low temperature side, the metal is Kotin grayed, reduces heat radiation, characterized The current introduction terminal according to claim 2 or 3 .

The thermoelectric conversion elements are solder-connected to the corresponding electrodes, and are provided to support and fix the connection portions between the thermoelectric conversion elements and the electrodes. The current introduction terminal according to any one of claims 1 to 3, wherein the current introduction terminal is made of a relatively low electrical insulating material.

Wherein the second electrode, the current supply destination end, is connected via a high-temperature superconducting device of claim 1, wherein the cable terminal, characterized in that.

4. The current introduction terminal according to claim 2, wherein the fourth electrode is connected to the other end of the current supply destination via a high-temperature superconducting element.

The current introduction terminal according to claim 1, comprising a plurality of stages of the thermoelectric conversion elements.

Wherein between the first electrode and the second electrode, a plurality of stages of thermoelectric conversion elements are arranged, cable terminal according to any one of claims 1 to 3, wherein.

A plurality of first conductivity type thermoelectric conversion elements are disposed between the first electrode and the second electrode,
The current introduction terminal according to claim 2 , wherein a plurality of stages of second-conductivity-type thermoelectric conversion elements are disposed between the third electrode and the fourth electrode.

One or a plurality of stages of first-conductivity-type thermoelectric conversion elements are disposed between the first electrode and the second electrode, and the one or more stages of the first-conductivity-type thermoelectric elements are disposed. A thermoelectric conversion element at an end of the conversion element is connected to one of the first and second electrodes, and further, a second conductivity type thermoelectric conversion element and another first conductivity type thermoelectric conversion element And comprising
One thermoelectric conversion element of the one or more stages of the first conductivity type thermoelectric conversion element and the second conductivity type thermoelectric conversion element are connected to each other in a pi (π) shape by a metal electrode. 1 thermoelectric element pair is formed, the second conductive type thermoelectric conversion element and the other first conductive type thermoelectric conversion element are connected to each other in a pi (π) type by a metal electrode, and the second thermoelectric conversion element is connected. An electrode of the second thermoelectric element pair opposite to the metal electrode of the second thermoelectric element pair is connected to the other of the first and second electrodes. The current introduction terminal according to claim 1 , wherein the current introduction terminal is provided.

One or a plurality of stages of first-conductivity-type thermoelectric conversion elements are disposed between the first electrode and the second electrode, and the one or more stages of the first-conductivity-type thermoelectric elements are disposed. A thermoelectric conversion element at an end of the conversion element is connected to one of the first and second electrodes;
Further, a first group of thermoelectric conversion elements is configured to include a second conductivity type thermoelectric conversion element and another first conductivity type thermoelectric conversion element, and the one or more stages of first conductivity A thermoelectric conversion element of one of the thermoelectric conversion elements of the type and the thermoelectric conversion element of the second conductivity type are connected in a pi (π) form with a metal electrode to form a first thermoelectric element pair, The second conductivity type thermoelectric conversion element and the other first conductivity type thermoelectric conversion element are connected to each other in a pi (π) shape with a metal electrode to form a second thermoelectric element pair, and the second An electrode on the opposite side of the metal electrode of the thermoelectric conversion element of the other first conductivity type of the thermoelectric element pair is connected to the other of the first and second electrodes;
One or a plurality of stages of second conductivity type thermoelectric conversion elements are disposed between the third electrode and the fourth electrode, and the one or more stages of second conductivity type thermoelectric elements. A thermoelectric conversion element at an end of the conversion element is connected to one of the third and fourth electrodes;
Furthermore, a first-conductivity-type thermoelectric conversion element and another second-conductivity-type thermoelectric conversion element are provided to form a second group of thermoelectric conversion elements. One thermoelectric conversion element among the thermoelectric conversion elements of the type and the thermoelectric conversion element of the first conductivity type are connected in a pi (π) form with a metal electrode to form a third thermoelectric element pair, A fourth thermoelectric element pair is formed by connecting a thermoelectric conversion element of the first conductivity type and the thermoelectric conversion element of the second conductivity type to the pi (π) type with a metal electrode, The electrode on the opposite side to the metal electrode of the thermoelectric conversion element of the other second conductivity type of the thermoelectric element pair is connected to the other of the third and fourth electrodes. Item 4. The current introduction terminal according to Item 2 or 3 .