JPH0653558A - Superconducting magnet device - Google Patents

Abstract

PURPOSE:To improve stability of a superconducting magnet by providing slits on a current route of a shielding plate in the same direction as that of a current flowing to a superconducting coil, and reducing its conductivity from that of a current route in a direction perpendicular to it. CONSTITUTION:When slits 7 are formed at a plurality of positions of a current route of a direction perpendicular to a current flowing to a superconducting coil 3 on a surface of a radiation shield 4 corresponding to the coil 3, eddy current 8 induced in the shield 4 does not flow across the slits. A flowing direction of the current 8 becomes perpendicular to a flowing direction of a current I of the coil 3, and since the flowing direction of the current 8 becomes parallel to a direction of a magnetic field formed by the coil 3, an electromagnetic force of a part in which the force becomes largest, if the slits 7, 7 are not provided, is largely reduced. Accordingly, a heat generation rate of the coil due to a vibration of a radiation shielding plate is reduced to suppress a radiation heat transfer rate of the coil by the plate to perform a superconducting magnet device having high stability.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は超電導磁石装置の安定化
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to stabilization of a superconducting magnet device.

【０００２】[0002]

【従来の技術】従来の超電導磁石装置を図２を参照して
説明する。2. Description of the Related Art A conventional superconducting magnet device will be described with reference to FIG.

【０００３】超電導磁石装置１は、冷却用の金属容器で
ある内槽２に入れた超電導コイル３と、この内槽を覆う
輻射シールド４、更にこれらを収容して真空状態に保持
する真空容器の外槽５等から構成されている。The superconducting magnet device 1 is composed of a superconducting coil 3 placed in an inner tank 2 which is a metal container for cooling, a radiation shield 4 for covering the inner tank, and a vacuum container for accommodating them and maintaining a vacuum state. It is composed of the outer tank 5 and the like.

【０００４】超電導コイル３は、入熱によって超電導導
体の温度が上昇して、臨界温度を超えると超伝導導体が
常電導状態に転移し、多大な発熱を生じる。このため、
超電導コイル３を安定に超電導状態に保つためには、超
電導コイル３を収容する内槽２で発生する熱及び内槽外
から侵入する熱を最小に抑えることが要求される。In the superconducting coil 3, the temperature of the superconducting conductor rises due to heat input, and when the temperature exceeds the critical temperature, the superconducting conductor is transformed into the normal conducting state and a great amount of heat is generated. For this reason,
In order to stably maintain the superconducting coil 3 in a superconducting state, it is required to minimize the heat generated in the inner tank 2 housing the superconducting coil 3 and the heat entering from the outside of the inner tank.

【０００５】このため、内槽２は熱伝導による侵入熱を
防ぐため低熱伝導材からなるコイル支持具６によって外
槽に対して宙つりに支持されている。いる。また、対流
熱伝達を防ぐために外槽内は真空に保持され、更に輻射
熱伝達を低減するために、常温の外槽壁と極低温の超電
導コイルを収容している内槽との間に輻射シールド４を
設けている。For this reason, the inner tank 2 is suspended from the outer tank by the coil support 6 made of a low heat conductive material in order to prevent heat from entering due to heat conduction. There is. In addition, a vacuum is maintained inside the outer tank to prevent convective heat transfer, and in order to further reduce radiant heat transfer, a radiation shield is provided between the outer tank wall at room temperature and the inner tank containing the cryogenic superconducting coil. 4 is provided.

【０００６】ところで、超電導磁石装置１に外部から変
動磁界が作用すると、この変動磁界によって外槽５の
壁、輻射シールド４のシールド板に渦電流が誘起され
る。この渦電流と超電導コイル３が作る強い磁界との作
用によって輻射シールド板に電磁力が発生し、この電磁
力によってシールド板が振動し、超電導コイルに発熱が
生じる。When a fluctuating magnetic field acts on the superconducting magnet device 1 from the outside, an eddy current is induced in the wall of the outer tank 5 and the shield plate of the radiation shield 4 by the fluctuating magnetic field. An electromagnetic force is generated in the radiation shield plate by the action of the eddy current and the strong magnetic field generated by the superconducting coil 3, the shield plate vibrates by the electromagnetic force, and heat is generated in the superconducting coil.

【０００７】[0007]

【発明が解決しようとする課題】一般に輻射シールド板
は、熱伝導率が大きく輻射率の小さい金属で構成される
が、一般に熱伝導率の大きな材料は導電率が大きいため
誘起される渦電流が大きくなり、シールド板の振動が大
きくなる問題がある。Generally, the radiation shield plate is made of a metal having a large thermal conductivity and a small emissivity. Generally, a material having a large thermal conductivity has a large electrical conductivity, so that the eddy current induced is large. However, there is a problem that the vibration of the shield plate becomes large.

【０００８】本発明はこの問題を解消するため、輻射シ
ールドの熱伝導を悪化させずに輻射シールドに発生する
振動を削減して、超電導コイルの発生熱、侵入熱を減少
して超電導磁石の安定性の向上を目的とする。In order to solve this problem, the present invention reduces the vibration generated in the radiation shield without deteriorating the heat conduction of the radiation shield, and reduces the heat generated by the superconducting coil and the heat entering the superconducting coil to stabilize the superconducting magnet. The purpose is to improve sex.

【０００９】[0009]

【課題を解決するための手段】超電導磁石コイルを覆う
輻射シールドが超電導磁石コイルの面と向かい合う面に
おいて、超電導コイルに流れる電流と同方向のシールド
板の電流経路にスリットを設けて、そこの導電率をそれ
と直角な方向の電流経路の導電率より小さくなるように
しておく。A radiation shield covering a superconducting magnet coil is provided with a slit in a current path of a shield plate in the same direction as a current flowing through the superconducting coil in a surface facing the surface of the superconducting magnet coil, and the conduction therethrough. The rate is kept smaller than the conductivity of the current path in the direction perpendicular to it.

【００１０】[0010]

【作用】輻射シールドの振動の要因となる輻射シールド
の電磁力は、輻射シールド板に誘起される渦電流と、超
電導コイルによる磁界との積に比例する。特に超電導コ
イル面に対応する輻射シールド面は超電導コイルとの距
離が近いためにその磁界が大きく電磁力も大きくなる。
超電導コイルによる磁界は図３に示すように、概略超電
導コイルに流れる電流Ｉ（矢印）に垂直な方向成分とな
る。したがって、この部分では輻射シールドの電磁力に
影響するのは輻射シールドに誘起する渦電流の内、超電
導コイルに流れる電流Ｉと同方向の成分のみとなる。The electromagnetic force of the radiation shield, which causes vibration of the radiation shield, is proportional to the product of the eddy current induced in the radiation shield plate and the magnetic field generated by the superconducting coil. In particular, the radiation shield surface corresponding to the surface of the superconducting coil has a large magnetic field and a large electromagnetic force because it is close to the superconducting coil.
As shown in FIG. 3, the magnetic field generated by the superconducting coil becomes a directional component substantially perpendicular to the current I (arrow) flowing in the superconducting coil. Therefore, in this portion, only the component in the same direction as the current I flowing through the superconducting coil affects the electromagnetic force of the radiation shield among the eddy currents induced in the radiation shield.

【００１１】本発明においては、この部分において、輻
射シールドの実効的な導電率のうち超電導コイルに流れ
る電流Ｉと同方向の電流経路の導電率をそれと直角な方
向の電流経路の導電率より小さくしているため、この部
分に誘起される渦電流は、超電導コイルに流れる電流と
直角な方向に制限される。この方向はこの部分での超電
導コイルのつくる磁界と同方向であり、ローレンツの法
則より同じ方向の電流と磁界では電磁力が発生しないた
め、結果として輻射シールドに作用する電磁力が低減さ
れることになる。電磁力が低減すれば、輻射シールドの
振動が減少し、輻射シールドと接続されている超電導コ
イルの振動も減少して、結果として超電導コイルの熱負
荷が低減できる。According to the present invention, in this portion, the conductivity of the current path in the same direction as the current I flowing through the superconducting coil, out of the effective conductivity of the radiation shield, is smaller than the conductivity of the current path in the direction perpendicular thereto. Therefore, the eddy current induced in this portion is limited to the direction perpendicular to the current flowing in the superconducting coil. This direction is the same direction as the magnetic field created by the superconducting coil in this part, and according to Lorentz's law, electromagnetic force does not occur in the current and magnetic field in the same direction, so the electromagnetic force acting on the radiation shield is reduced as a result. become. When the electromagnetic force is reduced, the vibration of the radiation shield is reduced, the vibration of the superconducting coil connected to the radiation shield is also reduced, and as a result, the heat load of the superconducting coil can be reduced.

【００１２】[0012]

【実施例】図１〜図４に示す実施例に基づいて本発明を
説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on the embodiments shown in FIGS.

【００１３】輻射シールド４のうち超電導コイル３と対
応する面には、超電導コイル３に流れる電流と直角な方
向の電流経路の複数箇所にスリット７を設ける。On the surface of the radiation shield 4 corresponding to the superconducting coil 3, slits 7 are provided at a plurality of positions in a current path in a direction perpendicular to the current flowing through the superconducting coil 3.

【００１４】輻射シールド４に誘起される渦電流８はこ
のスリットを横切って流れられないため、この部分での
渦電流８の流れる方向は超電導コイル３の電流Ｉの流れ
る方向と直角となる。即ち渦電流８の流れる方向が超電
導コイルのつくる磁界の方向と平行となるため、スリッ
ト７、７…が無ければ最も電磁力の大きくなるこの部分
での電磁力が大幅に削減されることになる。Since the eddy current 8 induced in the radiation shield 4 does not flow across this slit, the direction in which the eddy current 8 flows in this portion is perpendicular to the direction in which the current I in the superconducting coil 3 flows. That is, since the direction in which the eddy current 8 flows is parallel to the direction of the magnetic field created by the superconducting coil, the electromagnetic force in this portion, where the electromagnetic force is greatest without the slits 7, 7, is greatly reduced. .

【００１５】一方、輻射シールド４の熱伝導について
は、この部分での超電導コイル３に流れる方向と直角な
方向については、輻射シールド４を構成する金属材料の
良好な熱伝導率が確保されているため、輻射シールド４
の冷却には何も支障をきたすことはない。On the other hand, regarding the heat conduction of the radiation shield 4, in the direction perpendicular to the direction of flow in the superconducting coil 3 in this portion, good heat conductivity of the metal material forming the radiation shield 4 is secured. Therefore, radiation shield 4
There is nothing wrong with the cooling.

【００１６】[0016]

【発明の効果】本発明により、外部磁界を受ける超電導
磁石において、輻射シールド板に誘起される渦電流に起
因する輻射シールド板の振動により発生する超電導コイ
ルの発熱量を低減し、かつ輻射シールド板により超電導
コイルの輻射電熱量を抑えて安定性の高い超電導磁石を
提供できる。According to the present invention, in the superconducting magnet which receives an external magnetic field, the heat generation amount of the superconducting coil generated by the vibration of the radiation shield plate caused by the eddy current induced in the radiation shield plate is reduced, and the radiation shield plate is reduced. As a result, it is possible to provide a highly stable superconducting magnet by suppressing the amount of radiant heat of the superconducting coil.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明による超電導磁石装置の斜視図、FIG. 1 is a perspective view of a superconducting magnet device according to the present invention,

【図２】図１の断面図、FIG. 2 is a sectional view of FIG.

【図３】図２の機能説明図、3 is a functional explanatory diagram of FIG. 2,

【図４】図１の部分詳細図である。FIG. 4 is a partial detailed view of FIG.

【符号の説明】[Explanation of symbols]

１…超伝導磁石装置 ３…超伝導磁石コイル ４…輻射シールド ７…スリット 1 ... Superconducting magnet device 3 ... Superconducting magnet coil 4 ... Radiation shield 7 ... Slit

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】超電導コイルとこれを収納した内槽、この
内槽を覆う輻射シールド、さらにこれらを収納した真空
容器の外槽などから構成され、外部から変動磁界を受け
る超電導磁石装置において、 前記輻射シールドの前記超電導コイルと対応する面にお
いて、超電導コイル電流の流れる方向と同方向の電流経
路の導電率を、それと直角方向の導電率より小さくなる
ように形成したことを特徴とする超電導磁石装置。1. A superconducting magnet device which comprises a superconducting coil, an inner tank containing the superconducting coil, a radiation shield covering the inner tank, and an outer tank of a vacuum container containing the superconducting coil. A superconducting magnet device, characterized in that, on the surface of the radiation shield corresponding to the superconducting coil, the conductivity of a current path in the same direction as the direction of flow of the superconducting coil is formed to be smaller than the conductivity in the direction orthogonal thereto. . 【請求項２】輻射シールドの超電導コイルと対応する面
の超電導コイル電流の流れる方向に対して直角な方向の
電流経路に、複数のスリットを設けたことを特徴とする
請求項１に記載の超電導磁石装置2. The superconducting device according to claim 1, wherein a plurality of slits are provided in a current path of a surface of the radiation shield corresponding to the superconducting coil in a direction perpendicular to a direction in which the superconducting coil current flows. Magnet device