JP4477859B2 - Permanent current switch, superconducting magnet, and magnetic resonance imaging apparatus - Google Patents

Permanent current switch, superconducting magnet, and magnetic resonance imaging apparatus Download PDF

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JP4477859B2
JP4477859B2 JP2003382826A JP2003382826A JP4477859B2 JP 4477859 B2 JP4477859 B2 JP 4477859B2 JP 2003382826 A JP2003382826 A JP 2003382826A JP 2003382826 A JP2003382826 A JP 2003382826A JP 4477859 B2 JP4477859 B2 JP 4477859B2
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芳英 和田山
毅 和久田
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Hitachi Ltd
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本発明は、超電導コイルと永久電流スイッチを備える超電導磁石及びその応用装置に関する。   The present invention relates to a superconducting magnet including a superconducting coil and a permanent current switch, and an application device thereof.

永久電流モードで運転される超電導磁石の要素体である永久電流スイッチには、動作状態における擾乱に対して高い電磁気的な安定性が要求される。特開昭６１−２６９３０１号公報には、高い外部磁場中や、高い運転電流で動作する磁石に使用される永久電流スイッチの動作安定性を向上するための方法として、複数個の永久電流スイッチを電気的に並列接続して１スイッチ当りの電流容量を下げる方法が記載されている。   A permanent current switch which is an element of a superconducting magnet operated in the permanent current mode is required to have high electromagnetic stability against disturbances in an operating state. Japanese Patent Laid-Open No. 61-269301 discloses a plurality of permanent current switches as a method for improving the operational stability of a permanent current switch used in a magnet that operates in a high external magnetic field or at a high operating current. A method for reducing the current capacity per switch by electrically connecting them in parallel is described.

特開昭６１−２６９３０１号公報JP-A 61-269301

永久電流スイッチの動作不安定性は、スイッチがOFF状態（常電動状態）にある時のスイッチの電気抵抗を高くする必要性から、超電導フィラメントを内蔵する金属マトリックスの電気抵抗を高くしていることに起因するものである。つまり、スイッチがON状態（超電導状態）の時、超電導フィラメントに局所的な擾乱が生じると、電流が隣接する他の超電導フィラメントに転流するが、その際に金属マトリックスの発熱が大きく、結果として超電導線材の全域が常電導転移してしまう現象が生じる。従って、スイッチの安定性を確保するために、線材を細くして運転電流を下げる、あるいは永久電流回路に複数個のスイッチを並列配置してスイッチ当りの電流負荷を下げる等の手法がとられていた。   The instability of the permanent current switch is due to the necessity of increasing the electrical resistance of the switch when the switch is in the OFF state (normally driven state). It is due. In other words, when a local disturbance occurs in the superconducting filament when the switch is in the ON state (superconducting state), the current is commutated to other adjacent superconducting filaments, but at that time, the metal matrix generates a large amount of heat, and as a result A phenomenon occurs in which the entire area of the superconducting wire undergoes normal conduction transition. Therefore, in order to ensure the stability of the switch, a method such as reducing the operating current by thinning the wire or reducing the current load per switch by arranging a plurality of switches in parallel in the permanent current circuit is used. It was.

しかし、上記の複数個の永久電流スイッチを用いて高磁場中での使用や大電流運転に対応する方法は、磁石構造のコンパクト化を妨げる。また、電気配線構造に起因して複数のスイッチ間でインダクタンス、あるいは端子部の接続電気抵抗に差異が生じた場合、スイッチに流れる電流値に差異が生じるため、スイッチ全体として均等に電流を分担させることが困難である。   However, the method corresponding to the use in a high magnetic field and the large current operation using the plurality of permanent current switches described above prevents the magnet structure from being made compact. In addition, when there is a difference in inductance or connection electrical resistance between terminals due to the electrical wiring structure, a difference occurs in the current value flowing through the switch, so that the current is shared equally among the entire switch. Is difficult.

本発明は、高い電流負荷においても優れた動作安定性を有する永久電流スイッチ及びそれを組み込んだ超電導磁石を提供することを目的とする。   An object of the present invention is to provide a permanent current switch having excellent operational stability even at a high current load, and a superconducting magnet incorporating the permanent current switch.

上記目的を達成するため、本発明では、安定化金属の内部に複数本の超電導フィラメントが配置された超電導線と、超電導線を加熱するための加熱手段とを備える永久電流スイッチにおいて、超電導線の内部に配置された複数本の超電導フィラメントを、超電導線の長手方向の所定位置において、超電導材料によって相互に電気的に接続した。   To achieve the above object, in the present invention, in a permanent current switch comprising a superconducting wire in which a plurality of superconducting filaments are arranged inside a stabilizing metal, and a heating means for heating the superconducting wire, A plurality of superconducting filaments arranged inside were electrically connected to each other by a superconducting material at a predetermined position in the longitudinal direction of the superconducting wire.

また、安定化金属の内部に複数本の超電導フィラメントが配置された複数本の超電導線と、超電導線を加熱するための加熱手段とを備える永久電流スイッチにおいて、複数本の超電導線を撚線し、撚線内部の超電導フィラメントを、撚線の長手方向の所定位置において、超電導材料によって相互に電気的に接続した。   Further, in a permanent current switch comprising a plurality of superconducting wires in which a plurality of superconducting filaments are arranged inside the stabilizing metal and a heating means for heating the superconducting wires, the plurality of superconducting wires are twisted. The superconducting filaments inside the stranded wire were electrically connected to each other by a superconducting material at a predetermined position in the longitudinal direction of the stranded wire.

本発明によると、動作状態で永久電流スイッチに擾乱が生じた場合でも、常電導転移したフィラメントに流れる電流が速やかに隣接するフィラメントに転流するため大きなジュール発熱が生じることなしに、線材全体が超電導状態に復帰する。これは超電導線内部の超電導フィラメントに流れる電流の再配分に必要な時定数τは、線材両端部のフィラメントの接続抵抗Ｒと、スイッチを構成する線材のインダクタンスＬより、τ＝Ｌ／Ｒで表され、この時定数τを小さくするためにはインダクタンスＬを小さくすれば良いことによる。一般的に永久電流スイッチはそのインダクタンスを小さくするために無誘導巻されることが多く、スイッチのインダクタンスは平行配置された超電導線の長さに依存するため、電流再配分される線材長さを短くすれば時定数低減の効果が得られる。即ち、スイッチを構成する超電導線の長手方向に対して周期的あるいは部分的にフィラメント相互を超電導接続のような極めて低い電気抵抗で接続すれば、電流再配分の時定数が短くなり、結果としてスイッチ全体の動作安定性が確保できることになる。   According to the present invention, even when a disturbance occurs in the permanent current switch in the operating state, the current flowing through the normally conducting filament is quickly commutated to the adjacent filament, so that no large Joule heat is generated and the entire wire is Return to superconducting state. This is because the time constant τ necessary for redistribution of the current flowing in the superconducting filament inside the superconducting wire is expressed as τ = L / R from the connection resistance R of the filament at both ends of the wire and the inductance L of the wire constituting the switch. In order to reduce the time constant τ, the inductance L should be reduced. In general, a permanent current switch is often non-inductively wound in order to reduce its inductance, and the inductance of the switch depends on the length of superconducting wires arranged in parallel. If it is shortened, the effect of reducing the time constant can be obtained. In other words, if the filaments are connected to each other with a very low electrical resistance such as superconducting connection periodically or partially with respect to the longitudinal direction of the superconducting wire constituting the switch, the time constant of current redistribution is shortened. Overall operational stability can be ensured.

なお、超電導フィラメント相互を電気的に接続する個所を複数箇所設ける場合には、線材の長手方向に対して接続箇所の間隔が均等であることが好ましい。即ち、間隔が極度に異なると、最も間隔の長い領域の線材にて不安定性が生じやすくなる。なお、これら、超電導フィラメント相互を電気的に接続する個所の間隔と個数は、任意に設定できる。計算上は永久電流スイッチ用の超電導線の安定化材がＣｕ−Ｎｉであり、電気抵抗が無酸素銅と比較して約１００倍高い場合には、１００分割することが理想であるが、無誘導巻きの折り返し点でフィラメント相互を電気的に接続する場合のように２分割であっても効果が発揮できる。   In addition, when providing the several location which electrically connects superconducting filaments, it is preferable that the space | interval of a connection location is equal with respect to the longitudinal direction of a wire. That is, if the intervals are extremely different, instability is likely to occur in the wire having the longest interval. It should be noted that the interval and the number of locations where these superconducting filaments are electrically connected can be arbitrarily set. In calculation, when the stabilizer for the superconducting wire for the permanent current switch is Cu-Ni and the electric resistance is about 100 times higher than that of oxygen-free copper, it is ideal to divide it into 100. Even when the filaments are divided into two parts as in the case where the filaments are electrically connected at the turning point of the induction winding, the effect can be exhibited.

また超電導線内部のフィラメント相互を局所的に電気接続する手段として、鉛を含有する超電導合金を用いた。Ｐｂ−Ｂｉ等の鉛を含有する超電導合金は、臨界磁界が１Ｔ程度と比較的高く、永久電流スイッチが磁場中に配置されてもフィラメント相互の電気接続を超電導状態に保持できると共に、低融点であるため半田付けで接続処理することが可能となる。適用できるＰｂ合金としては、Ｐｂ−Ｂｉ，Ｐｂ−Ｓｎ，Ｐｂ−Ｉｎ等がある。   Also, a superconducting alloy containing lead was used as means for locally electrically connecting the filaments inside the superconducting wire. A superconducting alloy containing lead such as Pb-Bi has a relatively high critical magnetic field of about 1 T, and can maintain electrical connection between filaments in a superconducting state even when a permanent current switch is placed in the magnetic field, and has a low melting point. Therefore, connection processing can be performed by soldering. Applicable Pb alloys include Pb—Bi, Pb—Sn, Pb—In, and the like.

本発明によると、高い電流負荷においても優れた動作安定性を有する永久電流スイッチが得られる。そして、この永久電流スイッチを超電導コイルと組合せて超電導磁石を構成すると、永久電流回路の安定性が向上し、時間安定性に優れた超電導磁石が得られる。   According to the present invention, a permanent current switch having excellent operational stability even at a high current load can be obtained. When this supercurrent switch is combined with a superconducting coil to form a superconducting magnet, the stability of the permanent current circuit is improved, and a superconducting magnet having excellent time stability can be obtained.

以下、図面を参照して本発明の実施の形態を説明する。理解を容易にするため、以下の図において、同じ機能部分には同一の符号を付して説明する。   Embodiments of the present invention will be described below with reference to the drawings. In order to facilitate understanding, the same functional parts are denoted by the same reference numerals in the following drawings.

図１は、本発明による超電導磁石の電気回路を示す概略図である。この超電導磁石１０は、超電導コイル１１、永久電流スイッチ１３、保護抵抗１４を並列接続した回路に励磁電源１５を接続した構造を有する。図１に破線で示した部分１６は、超電導磁石の構造範囲を表す。永久電流スイッチ１３は、巻線された超電導線１７とこれを加熱するヒータ１８が内蔵された構造を有し、ヒータ電源１９によってヒータ１８をON／OFFすることによって超電導巻線１７の常電導／超電導を制御するものである。超電導磁石１０の励磁回路を永久電流モードにする手順は次の通りである。
(1) 永久電流スイッチ１３のヒータ１８をONとし、永久電流スイッチ１３をOFF（常電導）とする。
(2) 励磁電源１５により超電導コイル１１に通電する。
(3) 永久電流スイッチ１３のヒータ１８をOFFとし、永久電流スイッチ１３をON（超電導）にする。この操作で、超電導コイル１１と永久電流スイッチ１３からなる永久電流回路（閉回路）に電流が流れる。
(4) 励磁電源１５の電流を下げる。 FIG. 1 is a schematic diagram showing an electric circuit of a superconducting magnet according to the present invention. The superconducting magnet 10 has a structure in which an excitation power source 15 is connected to a circuit in which a superconducting coil 11, a permanent current switch 13, and a protective resistor 14 are connected in parallel. A portion 16 indicated by a broken line in FIG. 1 represents a structural range of the superconducting magnet. The permanent current switch 13 has a structure in which a wound superconducting wire 17 and a heater 18 for heating the same are built in, and the heater 18 is turned on / off by a heater power source 19 to thereby perform normal conduction / conduction of the superconducting winding 17. It controls superconductivity. The procedure for setting the exciting circuit of the superconducting magnet 10 to the permanent current mode is as follows.
(1) The heater 18 of the permanent current switch 13 is turned on, and the permanent current switch 13 is turned off (normal conduction).
(2) The superconducting coil 11 is energized by the excitation power supply 15.
(3) Turn off the heater 18 of the permanent current switch 13 and turn on the permanent current switch 13 (superconductivity). By this operation, a current flows through a permanent current circuit (closed circuit) composed of the superconducting coil 11 and the permanent current switch 13.
(4) Lower the current of the excitation power supply 15.

超電導コイル１１への通電速度を早くするためには、並列接続された永久電流スイッチ１３のOFF時の電気抵抗を高くし、永久電流スイッチ１３への分流を小さくする必要があり、永久電流スイッチ用の超電導線１７の安定化材にはＣｕ−Ｎｉが使用されることが多い。しかし、安定化材に高抵抗材を用いることは、動作状態における擾乱に対して電磁気的な安定性が小さくなるトレードオフ関係ある。   In order to increase the energization speed of the superconducting coil 11, it is necessary to increase the electrical resistance when the permanent current switch 13 connected in parallel is turned off, and to reduce the shunt to the permanent current switch 13, and for the permanent current switch. Cu-Ni is often used as a stabilizer for the superconducting wire 17. However, the use of a high-resistance material as the stabilizing material has a trade-off relationship that reduces electromagnetic stability against disturbance in the operating state.

（実施例１）
図２に、本発明による永久電流スイッチの一例の構造概要図を示す。図３は、その配線展開図である。 Example 1
FIG. 2 shows a structural schematic diagram of an example of the permanent current switch according to the present invention. FIG. 3 is an exploded view of the wiring.

永久電流スイッチを構成する超電導線材として、Ｃｕ−３０Ｎｉマトリックス内部に直径１０μｍのＮｂＴｉ超電導フィラメント２１を１０００本、多芯配置した直径０．６ｍｍの超電導線２２を用いた。この超電導線２２を長さ３０ｍ用い、二つ折りしてボビン２３に巻線した無誘導構造の永久電流スイッチ２０を作製した。その後、線材を二つ折りした領域２４のＣｕ−Ｎｉを化学的に溶解除去した後、その溶解除去した箇所に露出したＮｂ−Ｔｉ超電導フィラメントをＰｂ−Ｂｉ合金で半田付けすることで、フィラメント相互を超電導材料（Ｐｂ−Ｂｉ合金）で電気的に接続した。実際の永久電流スイッチには、超電導線２２を加熱する手段としてヒータ線が設けられているが、加熱手段は本発明の本質に係わるものではないため、図の見やすさを考えてヒータ線は図示を省略した。永久電流スイッチ２０の超電導線材の両端部は永久電流スイッチ口出し部２５から引き出され、磁場発生用の超電導コイル１１の超電導線１２の端部と接続部２６ａ，２６ｂで互いに超電導接続される。図３に破線で示した領域２７は、永久電流スイッチ２０の構造範囲を示している。   As a superconducting wire constituting the permanent current switch, a superconducting wire 22 having a diameter of 0.6 mm in which 1000 NbTi superconducting filaments 21 having a diameter of 10 μm and a multicore arrangement are arranged inside a Cu-30Ni matrix was used. Using this superconducting wire 22 having a length of 30 m, a permanent current switch 20 having a non-inductive structure in which the superconducting wire 22 was folded in two and wound around a bobbin 23 was produced. Thereafter, Cu-Ni in the region 24 in which the wire is folded in half is chemically dissolved and removed, and then the Nb-Ti superconducting filament exposed in the dissolved and removed portion is soldered with a Pb-Bi alloy, whereby the filaments are mutually bonded. Electrical connection was made with a superconducting material (Pb-Bi alloy). In an actual permanent current switch, a heater wire is provided as a means for heating the superconducting wire 22, but the heating means is not related to the essence of the present invention. Was omitted. Both ends of the superconducting wire rod of the permanent current switch 20 are drawn out from the permanent current switch lead-out portion 25, and are superconductively connected to each other at the end portions of the superconducting wire 12 of the superconducting coil 11 for magnetic field generation and the connecting portions 26a and 26b. A region 27 indicated by a broken line in FIG. 3 indicates a structural range of the permanent current switch 20.

作製した永久電流スイッチ２０を液体ヘリウムに漬浸した状態で通電試験したところ、スイッチがON状態（超電導状態）で通電できた最大電流は外部磁場が１Ｔの条件下で８００Ａであり、超電導線が本来有する臨界電流特性に近い通電性能を達成することができた。なお、無誘導巻きの折返し部２４のフィラメント相互を超電導材料で接続しない以外は、同一の構造を有する永久電流スイッチを比較用として作成したところ、比較用の永久電流スイッチは動作不安定性を示し、約５００Ａ程度の電流値で常電導転移した。即ち、線材の長手方向に対して局所的にフィラメント相互を接続することによって永久電流スイッチの動作安定性が向上することが実験によっても確認された。   When the manufactured permanent current switch 20 was immersed in liquid helium, an energization test was performed, and the maximum current that could be energized when the switch was in the ON state (superconducting state) was 800 A under the condition that the external magnetic field was 1 T. The current-carrying performance close to the inherent critical current characteristics could be achieved. In addition, when the permanent current switch having the same structure was prepared for comparison except that the filaments of the non-inductive winding part 24 were not connected with a superconducting material, the comparative permanent current switch showed operational instability, Normal conduction transition was made at a current value of about 500A. That is, it has also been confirmed by experiments that the operation stability of the permanent current switch is improved by locally connecting the filaments in the longitudinal direction of the wire.

なお、フィラメント相互を超電導接続する方法として、この例ではＰｂ−Ｂｉ合金による半田付けを用いたが、接続手法に関する制限は特になく、フィラメントの特性に劣化がない範囲でこれらが相互に超電導接続のごとく低電気抵抗で接続されていればよい。また、超電導フィラメント相互を接続する長手方向の間隔及び数は、本例に示したように、永久電流スイッチを構成する超電導フィラメントの全長の中間位置の１箇所に限られるものではない。一般に、超電導フィラメント相互を接続する位置の長手方向の間隔が短いほどその効果が大きいが、スイッチ形状に応じて任意に選択することができる。   In this example, soldering with a Pb-Bi alloy was used as a method for superconducting the filaments. However, there is no particular limitation on the connection method, and these are mutually superconducting as long as the characteristics of the filaments are not deteriorated. As long as it is connected with low electrical resistance. Further, the interval and the number in the longitudinal direction for connecting the superconducting filaments are not limited to one in the middle of the total length of the superconducting filaments constituting the permanent current switch, as shown in this example. In general, the effect is greater as the distance in the longitudinal direction at the position where the superconducting filaments are connected to each other is shorter, but can be arbitrarily selected according to the switch shape.

（実施例２）
図４は、本発明による永久電流スイッチの他の例の配線展開図である。ここでは、永久電流スイッチ４０を構成する超電導線材として実施例１と同様の超電導線材２２を長さ３０ｍ用い、永久電流スイッチとして巻線する前に、次の処理を施した。長手方向の６ｍ毎に、超電導線材２２の銅合金の安定化材を長さ約５ｍｍ除去し、安定化材が除去された領域４１ａ〜４１ｄに露出した超電導フィラメント２１相互をＰｂ−Ｂｉ半田により電気接続した。その後に無誘導巻線して永久電流スイッチ４０を作製した。 (Example 2)
FIG. 4 is a wiring development view of another example of the permanent current switch according to the present invention. Here, a superconducting wire 22 similar to that of Example 1 was used as the superconducting wire constituting the permanent current switch 40 in a length of 30 m, and the following processing was performed before winding as a permanent current switch. Every 6 m in the longitudinal direction, the copper alloy stabilizing material of the superconducting wire 22 is removed by about 5 mm in length, and the superconducting filaments 21 exposed in the regions 41a to 41d from which the stabilizing material has been removed are electrically connected by Pb-Bi solder. Connected. Thereafter, non-inductive winding was performed to produce a permanent current switch 40.

作製された永久電流スイッチを液体ヘリウムに漬浸した状態で通電試験したところ、永久電流スイッチがON状態（超電導状態）で通電できた最大電流は、外部磁場が１Ｔの条件下で８２５Ａであった。本実施例においても、超電導線２２が本来有する臨界電流特性に近い通電性能を達成することができた。即ち、予め超電導線材の長手方向の所定位置で局所的に超電導フィラメント相互を接続した後に永久電流スイッチを作製しても、その動作安定性が向上することが実験によっても確認された。これはＰｂ合金が比較的柔らかく、変形性に優れていることによるものである。   When the manufactured permanent current switch was immersed in liquid helium, an energization test was performed. As a result, the maximum current that could be energized in the ON state (superconducting state) of the permanent current switch was 825 A under the condition that the external magnetic field was 1T. . Also in this example, it was possible to achieve energization performance close to the critical current characteristics inherent to the superconducting wire 22. That is, it has been confirmed by experiments that even if a permanent current switch is manufactured after locally connecting the superconducting filaments at a predetermined position in the longitudinal direction of the superconducting wire, the operation stability is improved. This is because the Pb alloy is relatively soft and has excellent deformability.

（実施例３）
図５は、本発明による永久電流スイッチの他の例の配線展開図である。ここでは、永久電流スイッチ５０を構成する超電導線材として、実施例１と同様の線材を長さ３０ｍに渡って３本撚り合わせた撚線５２を用いた。この撚線５２を二つ折りしてボビンに巻線し、無誘導構造の永久電流スイッチ５０を作製した。その後、線材の二つ折りした領域２４のＣｕ−Ｎｉ合金を硝酸によって化学的に溶解除去し、露出した超電導フィラメントをＰｂ−Ｂｉ合金で半田付けすることで、フィラメント相互を超電導材料で電気的に接続した。 (Example 3)
FIG. 5 is a wiring development view of another example of the permanent current switch according to the present invention. Here, as a superconducting wire constituting the permanent current switch 50, a stranded wire 52 in which three wires similar to those in Example 1 were twisted over a length of 30 m was used. The twisted wire 52 was folded in half and wound around a bobbin to produce a non-inductive permanent current switch 50. Thereafter, the Cu—Ni alloy in the folded region 24 of the wire is chemically dissolved and removed with nitric acid, and the exposed superconducting filament is soldered with a Pb—Bi alloy, thereby electrically connecting the filaments with the superconducting material. did.

作製された永久電流スイッチ５０を液体ヘリウムに漬浸した状態で通電試験したところ、永久電流スイッチがON状態（超電導状態）で通電できた最大電流は外部磁場が１Ｔの条件下で２３００Ａであり、超電導線が本来有する臨界電流特性に近い通電性能を達成することができた。即ち、素線のみならず撚線５２においても、超電導フィラメント相互を長手方向の所定位置において部分的に電気接続することにより、超電導フィラメント間の転流に必要な時定数が短くなり、結果として動作安定性が改善されることが確認された。これは、従来技術のごとく永久電流スイッチを電気的に並列接続することで、ひとつのスイッチ当りの電流分担率を下げるという手法をとることなしに、超電導線を撚線にし、線材自体の電流容量を増加させることでも、優れた動作安定性を有するスイッチが提供できることを示している。   When the energization test was performed with the manufactured permanent current switch 50 immersed in liquid helium, the maximum current that could be energized when the permanent current switch was in the ON state (superconducting state) was 2300 A under the condition that the external magnetic field was 1T. The current-carrying performance close to the critical current characteristics inherent in the superconducting wire was achieved. That is, not only in the strands but also in the stranded wire 52, the superconducting filaments are partially electrically connected to each other at a predetermined position in the longitudinal direction, so that the time constant required for commutation between the superconducting filaments is shortened, resulting in operation. It was confirmed that the stability was improved. This is because, as in the prior art, the permanent current switches are electrically connected in parallel, and the current capacity of the wire itself is made by twisting the superconducting wire without taking the method of reducing the current sharing ratio per switch. It is shown that a switch having excellent operational stability can be provided even by increasing.

（実施例４）
実施例３に示した永久電流スイッチを、永久電流モードで運転される超電導磁石に組み込んで、図４の回路図に示した超電導磁石を作製し、励磁試験を行った。永久電流スイッチ１３がOFF状態（スイッチを加熱し常電導とした状態）で外部の励磁電源１５により超電導コイル１１を励磁した後に、永久電流スイッチ１３をON状態（ヒータ加熱を停止し、超電導状態とする）として永久電流モードとした。 Example 4
The permanent current switch shown in Example 3 was incorporated into a superconducting magnet operated in the permanent current mode to produce the superconducting magnet shown in the circuit diagram of FIG. 4, and an excitation test was performed. After the superconducting coil 11 is excited by the external excitation power source 15 when the permanent current switch 13 is in the OFF state (the switch is heated to normal conduction), the permanent current switch 13 is in the ON state (heater heating is stopped and the superconducting state is The permanent current mode.

永久電流回路に流れる電流は７００Ａで、超電導コイル１１の発生する磁場は、コイル中心で４．０Ｔであった。永久電流スイッチ１３が配置された場所での磁場は約１Ｔであったが、永久電流スイッチ部１３の擾乱によるクエンチは発生せず高安定な特性が得られた。   The current flowing through the permanent current circuit was 700 A, and the magnetic field generated by the superconducting coil 11 was 4.0 T at the coil center. Although the magnetic field at the place where the permanent current switch 13 was disposed was about 1T, quenching due to the disturbance of the permanent current switch portion 13 did not occur, and highly stable characteristics were obtained.

（実施例５）
図６は、本発明による超電導磁石を組み込んだ磁気共鳴イメージング装置の外観図を示す図である。図７はこれら磁気共鳴イメージング装置を構成する機器類の構成ブロック図を示す。 (Example 5)
FIG. 6 is an external view of a magnetic resonance imaging apparatus incorporating a superconducting magnet according to the present invention. FIG. 7 shows a configuration block diagram of the devices constituting these magnetic resonance imaging apparatuses.

実施例４で得られた超電導磁石６１ａ，６１ｂを上下に対向配置し、その間隙部に均一磁場を発生させた。患者（被検体）は、移動テーブル６２に寝た状態で、超電導磁石６１ａ，６１ｂの間の均一磁場発生空間に挿入される。さらに一対の傾斜磁場印加手段、高周波磁場を被検体に対し送信すると共に被検体からの磁気共鳴信号を受信する高周波送受信手段、高周波送受信手段及び傾斜磁場印加手段に接続され高周波磁場と傾斜磁場とを制御すると共に核磁気共鳴信号の取込みを制御し画像処理を行なう制御手段６５を設けることで、図６に示すような磁気共鳴イメージング装置を構成した。なお、傾斜磁場印加手段と高周波送受信手段は、超電導磁石と一体構造である。   The superconducting magnets 61a and 61b obtained in Example 4 were vertically arranged opposite to each other, and a uniform magnetic field was generated in the gap portion. The patient (subject) is inserted into the uniform magnetic field generation space between the superconducting magnets 61 a and 61 b while lying on the moving table 62. Further, a pair of gradient magnetic field applying means, a high frequency transmission / reception means for transmitting a high frequency magnetic field to the subject and receiving a magnetic resonance signal from the subject, a high frequency transmission / reception means and a gradient magnetic field application means are connected to the high frequency magnetic field and the gradient magnetic field. A magnetic resonance imaging apparatus as shown in FIG. 6 is configured by providing control means 65 for controlling and taking in nuclear magnetic resonance signals and performing image processing. Note that the gradient magnetic field applying means and the high-frequency transmitting / receiving means are integrated with the superconducting magnet.

対向配置した一対の超電導磁石６１ａ，６１ｂの中央部の空間に、約２．０Ｔの磁場を永久電流状態でかつ、擾乱に対して高安定に発生し、保持することができた。これにより、磁気共鳴原理を利用したイメージング撮影が繰り返される作業が長期間にわたって安定して実施できるようになった。   A magnetic field of about 2.0 T was generated in a permanent current state and highly stable against disturbance in the space at the center of the pair of superconducting magnets 61a and 61b arranged opposite to each other, and could be held. As a result, it has become possible to stably carry out the operation of repeating imaging photography using the magnetic resonance principle over a long period of time.

本発明による超電導磁石の電気回路を示す概略図。Schematic which shows the electric circuit of the superconducting magnet by this invention. 本発明による永久電流スイッチの一例の構造概要図。1 is a schematic structural diagram of an example of a permanent current switch according to the present invention. 本発明による永久電流スイッチの一例の配線展開図。The wiring expanded view of an example of the permanent current switch by this invention. 本発明による永久電流スイッチの他の例の配線展開図。The wiring expanded view of the other example of the permanent current switch by this invention. 本発明による永久電流スイッチの他の例の配線展開図。The wiring expanded view of the other example of the permanent current switch by this invention. 本発明による超電導磁石を組み込んだ磁気共鳴イメージング装置の外観図。1 is an external view of a magnetic resonance imaging apparatus incorporating a superconducting magnet according to the present invention. 本発明による超電導磁石を組み込んだ磁気共鳴イメージング装置の構成要素ブロック図。1 is a block diagram of components of a magnetic resonance imaging apparatus incorporating a superconducting magnet according to the present invention.

符号の説明Explanation of symbols

１０：超電導磁石、１１：超電導コイル、１２：超電導コイルの超電導線、１３：永久電流スイッチ、１４：保護抵抗、１５：励磁電源、１７：超電導線、１８：ヒータ、１９：ヒータ電源、２０：永久電流スイッチ、２１：超電導フィラメント、２２：超電導線、２３：ボビン、２４：線材を二つ折りした領域、２５：永久電流スイッチ口出し部、２６ａ，２６ｂ：接続部、４０：永久電流スイッチ、４１ａ〜４１ｄ：安定化材が除去された領域、５０：永久電流スイッチ、５２：撚線、６１ａ，６１ｂ：超電導磁石、６２：移動テーブル、６５：制御手段   10: Superconducting magnet, 11: Superconducting coil, 12: Superconducting wire of superconducting coil, 13: Permanent current switch, 14: Protection resistor, 15: Excitation power source, 17: Superconducting wire, 18: Heater, 19: Heater power source, 20: Permanent current switch, 21: Superconducting filament, 22: Superconducting wire, 23: Bobbin, 24: Area where wire rod is folded in half, 25: Permanent current switch opening part, 26a, 26b: Connection part, 40: Permanent current switch, 41a- 41d: Area from which stabilizing material has been removed, 50: Permanent current switch, 52: Twisted wire, 61a, 61b: Superconducting magnet, 62: Moving table, 65: Control means

Claims (8)

安定化金属の内部に複数本の超電導フィラメントが配置された超電導線と、前記超電導線を加熱するための加熱手段とを備える永久電流スイッチにおいて、
前記超電導線の内部に配置された複数本の超電導フィラメントは、当該超電導線の長手方向の所定位置において、超電導材料によって相互に電気的に接続され、
前記超電導線は無誘導巻された構造を有し、前記超電導線の長手方向の所定位置は無誘導巻の線材折り返し位置であることを特徴とする永久電流スイッチ。 In a permanent current switch comprising a superconducting wire in which a plurality of superconducting filaments are arranged inside a stabilizing metal, and heating means for heating the superconducting wire,
A plurality of superconducting filaments arranged inside the superconducting wire are electrically connected to each other by a superconducting material at a predetermined position in the longitudinal direction of the superconducting wire ,
The superconducting wire has a non-inductive winding structure, and the predetermined position in the longitudinal direction of the superconducting wire is a non-inductive winding wire folding position . 安定化金属の内部に複数本の超電導フィラメントが配置された複数本の超電導線と、前記超電導線を加熱するための加熱手段とを備える永久電流スイッチにおいて、
前記複数本の超電導線は撚線され、撚線内部の超電導フィラメントは、当該撚線の長手方向の所定位置において、超電導材料によって相互に電気的に接続され、
前記超電導線は無誘導巻された構造を有し、前記超電導線の長手方向の所定位置は無誘導巻の線材折り返し位置であることを特徴とする永久電流スイッチ。 In a permanent current switch comprising a plurality of superconducting wires in which a plurality of superconducting filaments are arranged inside a stabilizing metal, and heating means for heating the superconducting wires,
The plurality of superconducting wires are stranded, and the superconducting filaments inside the stranded wire are electrically connected to each other by a superconducting material at a predetermined position in the longitudinal direction of the stranded wire ,
The superconducting wire has a non-inductive winding structure, and the predetermined position in the longitudinal direction of the superconducting wire is a non-inductive winding wire folding position . 請求項１又は２記載の永久電流スイッチにおいて、前記超電導フィラメントを相互に電気的に接続する超電導材料は鉛を含有する超電導合金であることを特徴とする永久電流スイッチ。   3. The permanent current switch according to claim 1, wherein the superconducting material for electrically connecting the superconducting filaments to each other is a superconducting alloy containing lead. 請求項１〜３のいずれか１項記載の永久電流スイッチにおいて、前記長手方向の所定位置において前記安定化金属が前記超電導材料によって局所的に置換されていることを特徴とする永久電流スイッチ。 The permanent current switch according to any one of claims 1 to 3 , wherein the stabilizing metal is locally replaced by the superconducting material at a predetermined position in the longitudinal direction. 安定化金属の内部に複数本の超電導フィラメントが配置された超電導線と、前記超電導線を加熱するための加熱手段とを備える永久電流スイッチにおいて、In a permanent current switch comprising a superconducting wire in which a plurality of superconducting filaments are arranged inside a stabilizing metal, and heating means for heating the superconducting wire,
前記超電導線の内部に配置された複数本の超電導フィラメントは、当該超電導線の長手方向の所定位置において、超電導材料によって相互に電気的に接続され、A plurality of superconducting filaments arranged inside the superconducting wire are electrically connected to each other by a superconducting material at a predetermined position in the longitudinal direction of the superconducting wire,
前記長手方向の所定位置において前記安定化金属が前記超電導材料によって局所的に置換されていることを特徴とする永久電流スイッチ。The permanent current switch, wherein the stabilizing metal is locally replaced by the superconducting material at a predetermined position in the longitudinal direction. 安定化金属の内部に複数本の超電導フィラメントが配置された複数本の超電導線と、前記超電導線を加熱するための加熱手段とを備える永久電流スイッチにおいて、
前記複数本の超電導線は撚線され、撚線内部の超電導フィラメントは、当該撚線の長手方向の所定位置において、超電導材料によって相互に電気的に接続され、
前記長手方向の所定位置において前記安定化金属が前記超電導材料によって局所的に置換されていることを特徴とする永久電流スイッチ。 In a permanent current switch comprising a plurality of superconducting wires in which a plurality of superconducting filaments are arranged inside a stabilizing metal, and heating means for heating the superconducting wires ,
The plurality of superconducting wires are stranded, and the superconducting filaments inside the stranded wire are electrically connected to each other by a superconducting material at a predetermined position in the longitudinal direction of the stranded wire,
The permanent current switch, wherein the stabilizing metal is locally replaced by the superconducting material at a predetermined position in the longitudinal direction. 磁場発生用の超電導コイルと、前記超電導コイルと並列に接続された永久電流スイッチとを含む超電導磁石において、
前記永久電流スイッチとして請求項１〜６のいずれか１項記載の永久電流スイッチを備えたことを特徴とする超電導磁石。 In a superconducting magnet including a superconducting coil for generating a magnetic field and a permanent current switch connected in parallel with the superconducting coil,
Superconducting magnet, comprising the persistent current switch of any one of claims 1-6 as the permanent current switch. 磁場を発生するための超電導磁石と、一対の傾斜磁場印加手段と、高周波磁場を被検体に対して送信すると共に被検体からの磁気共鳴信号を受信する高周波送受信手段と、前記高周波送受信手段及び前記傾斜磁場印加手段を制御すると共に前記磁気共鳴信号の取込みを制御し画像処理を行なう手段とを含む磁気共鳴イメージング装置において、
前記超電導磁石として請求項７記載の超電導磁石を備えることを特徴とする磁気共鳴イメージング装置。 A superconducting magnet for generating a magnetic field; a pair of gradient magnetic field applying means; a high frequency transmitting / receiving means for transmitting a high frequency magnetic field to the subject and receiving a magnetic resonance signal from the subject; A magnetic resonance imaging apparatus including means for controlling the gradient magnetic field applying means and controlling the capture of the magnetic resonance signal to perform image processing,
A magnetic resonance imaging apparatus comprising the superconducting magnet according to claim 7 as the superconducting magnet.
JP2003382826A 2003-11-12 2003-11-12 Permanent current switch, superconducting magnet, and magnetic resonance imaging apparatus Expired - Fee Related JP4477859B2 (en)

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