JPS6388810A - Superconducting magnet - Google Patents
Superconducting magnetInfo
- Publication number
- JPS6388810A JPS6388810A JP61233192A JP23319286A JPS6388810A JP S6388810 A JPS6388810 A JP S6388810A JP 61233192 A JP61233192 A JP 61233192A JP 23319286 A JP23319286 A JP 23319286A JP S6388810 A JPS6388810 A JP S6388810A
- Authority
- JP
- Japan
- Prior art keywords
- superconducting coil
- ground
- superconducting
- coil
- time
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000002085 persistent effect Effects 0.000 claims description 11
- 230000005347 demagnetization Effects 0.000 abstract description 4
- 230000005284 excitation Effects 0.000 abstract description 4
- 230000000694 effects Effects 0.000 description 5
- 230000002159 abnormal effect Effects 0.000 description 4
- 230000015556 catabolic process Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000005481 NMR spectroscopy Methods 0.000 description 1
- 238000002591 computed tomography Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000002887 superconductor Substances 0.000 description 1
Landscapes
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
この発明は、ＮＭＲ−ＣＴ （核磁気共鳴現象を利用し
たコンピュータ断層撮影装置）用超電導マグネット、特
に超電導コイルの対地絶縁破壊を防止すると共にアース
経由の電流の廻り込みを防止する超電導マグネットに関
するものである。[Detailed Description of the Invention] [Industrial Application Field] This invention is a superconducting magnet for NMR-CT (computed tomography apparatus using nuclear magnetic resonance phenomenon), particularly for preventing ground dielectric breakdown of superconducting coils and for grounding. This relates to a superconducting magnet that prevents current from flowing through the magnet.
第２図及び第３図は従来の超電導マグネットの励磁、消
磁時の結線図である。図において、（１）は超電導コイ
ル、（，２）はこの超電導コイル（１）の両端間に接続
され、超電導コイル（１）を永久電流状態で運転するた
めの永久電流スイッチ、（３）はこれら超電導コイル（
１）と永久電流スイッチ（２）を収納する極低温容器、
（りはこの極低温容器（３）のアース、（５）は超電導
コイル（１）をアースするためＫその一端（第３図では
下端）を極低温容器（３）Ｋ接続した導線、（６）は超
電導コイル（１）を励磁または消磁するための電源、（
り）はこの電源（６）のアース、モして（ｇ）は超電導
コイル（１）と電源（６）とを接続し、或は切り離すた
めのコネクターである。FIGS. 2 and 3 are wiring diagrams for excitation and demagnetization of conventional superconducting magnets. In the figure, (1) is a superconducting coil, (,2) is a persistent current switch connected between both ends of this superconducting coil (1) to operate the superconducting coil (1) in a persistent current state, and (3) is a persistent current switch. These superconducting coils (
1) and a cryogenic container containing the persistent current switch (2);
(This is the ground of the cryogenic container (3), (5) is the conductor wire whose one end (lower end in Fig. 3) is connected to the cryogenic container (3) K in order to ground the superconducting coil (1), (6) ) is a power source for exciting or demagnetizing the superconducting coil (1), (
(g) is a connector for connecting or disconnecting the superconducting coil (1) and the power source (6).
従来の超電導マグネットは上記のように構成され、超電
導コイル（１）と電源（Ｘ）とがコネクター（＃）Ｋよ
って接続されている状態において、第一図の場合には、
超電導コイル（１）は、その消磁中又は励磁中（この時
には永久電流スイッチ（，２）はＯＦＦされている）、
コネクター（ｔ）を通じてｔＳ（６）側でアースされて
電位固定されている。A conventional superconducting magnet is constructed as described above, and in the case of Fig. 1, when the superconducting coil (1) and the power source (X) are connected by the connector (#) K,
The superconducting coil (1) is demagnetized or excited (at this time, the persistent current switch (2) is turned off),
The potential is fixed by grounding on the tS (6) side through the connector (t).
しかしながら、超電導コイル（１）を永久電流運転する
ため忙〔この時、永久電流スイッチ（コ〕はＯＮされる
〕超電導コイル（１）と電源（６）との接続をコネクタ
ー（１）で切り離した状態では、超電導コイル（１）側
の電位がアースに対して完全に浮動した状態となる。However, the connection between the superconducting coil (1) and the power source (6) was disconnected using the connector (1) while the superconducting coil (1) was being operated with persistent current (at this time, the persistent current switch was turned on). In this state, the potential on the superconducting coil (1) side is completely floating with respect to ground.
このような電位浮動状態を防止するために、第３図の超
電導マグネットが考えられた。しか［７ながら、超電導
コイル（１）の励磁中又は消磁中、電源（６）側のアー
ス（り）と超電導コイル（１） ９１のアース（りとの
間ＫＩＩＥ位差が発生し、この電位差を両アース（り）
、 （＋）間に存在する抵抗とにより定まる電流が電
源側アース（り）とコイル側アース（りとの間に流れて
しまう。In order to prevent such a potential floating state, the superconducting magnet shown in FIG. 3 was devised. However, during excitation or demagnetization of the superconducting coil (1), a KIIE potential difference occurs between the ground (RI) on the power supply (6) side and the ground (RI) of the superconducting coil (1) 91, and this potential difference Both earths
, (+), and a current determined by the resistance that exists between the terminals (+) flows between the power supply side ground (RI) and the coil side ground (RI).
上記のような従来の超電導マグネットでは、第２図の場
合には、超電導コイル（１）と電源（６）とをコネクタ
ー（１）で切り離した際ｗｍ＊導コ導層イル）の電位が
不安定となシ、超電導コイル（１）はヒ
超電導破壊等によって超電導コイル（１）■極低温容器
（、ｙ）の間に発生される異常電位で対地絶縁破壊して
しまうという問題点があった。又、第３図の場合には、
超電導コイル（１）と電源（６）とをコネク尺ｇ ）で
接続した上で励磁または消磁する際に、コイル側アース
（＜＝）とｔｔｉｉｔ側アース（り）の間に廻り込み電
流が発生してしまうという問題もがあった。In the conventional superconducting magnet as described above, in the case of Fig. 2, when the superconducting coil (1) and power source (6) are separated by the connector (1), the potential of wm However, when it comes to stability, the superconducting coil (1) has a problem in that the abnormal potential generated between the superconducting coil (1) and the cryogenic container (,y) causes dielectric breakdown to the ground due to superconductor breakdown. . Also, in the case of Figure 3,
When the superconducting coil (1) and the power source (6) are connected with a connector g) and then energized or demagnetized, a current flows around between the coil side ground (<=) and the ttiit side ground (ri). There was also the problem of doing so.
この発明は、このような問題点を解決するためＫなされ
たもので、超電導コイルと電源を切り離した状態におい
て、超電導コイルとアース間に発生される異常電圧で超
電導コイルに高い対地間圧が加わることを防止すると共
和、超電導コイルの励磁時又は消磁時における両アース
経由の電流のｍｐ込みを防止する超電導マグネットを得
ることを目的とする。This invention was made to solve these problems, and when the superconducting coil and the power supply are disconnected, high ground pressure is applied to the superconducting coil due to the abnormal voltage generated between the superconducting coil and the ground. It is an object of the present invention to provide a superconducting magnet that prevents current from flowing through both earths during excitation or demagnetization of a superconducting coil.
この発明に係る超電導マグネットは、超電導コイル上の
任意の一点と極低温容器の間に逆並列接続ダイオードを
設けたものである。The superconducting magnet according to the present invention has an anti-parallel connected diode between an arbitrary point on a superconducting coil and a cryogenic container.
この発明においては、通常、極低温時のダイオードの順
方向抵抗（ダイオードのターンオン電圧以下の時大抵抗
となシ、又ターンオン後は＃１ぼ定電流特性を有する）
特性を利用して超電導コイルを抵抗接地している。In this invention, the forward resistance of the diode at extremely low temperatures (the resistance is large when the diode turn-on voltage is lower than that, and after turn-on, the diode has approximately #1 constant current characteristics)
This property is used to ground the superconducting coil with resistance.
第１図はこの発明の一奥施例を示す結線図であり１図に
鉛いて（１）〜（４１） 、 （Ａ）〜（ｒ）は従来例
と同一のものである。（９）は互いに逆並列接続された
ダイオード（極低温でターンオン特性を示す）・ ４’
＋
であり、これは超電導コイル（１）上の任意の一点例え
ば第１図では上端と低温容器（３）とを接続している。FIG. 1 is a wiring diagram showing a further embodiment of the present invention, and as shown in FIG. 1, (1) to (41) and (A) to (r) are the same as the conventional example. (9) are diodes connected in antiparallel to each other (showing turn-on characteristics at extremely low temperatures) 4'
+, which connects an arbitrary point on the superconducting coil (1), for example, the upper end in FIG. 1, and the cryogenic vessel (3).
上記のように構成された超電導マグネツ）においては、
互いに逆並列接続されたダイオード（９）が超電導コイ
ル（１）の−点と極低温容器（３）を接続しているので
、超電導コイル（１）のダイオード接続箇所と極低温容
器（３）との間に発生される電位差は常時逆並列接続ダ
イオード（ｑ）の極低温時の順方向ターンオン電圧（こ
のターンオン電圧はｌθ〔ｖ〕程度以下であシ、ターン
オン後の電圧降下は数ＣＶ）程度になる）以下に保持さ
れる。通常、超電導コイル（１）を励磁又は消磁する（
永久電流スイッチ（コ）はＯＦＦされる）際のｔ源（５
）側電圧を、逆並列接続ダイオード（９）が接続される
超電導コイル（１）の接続箇所と極低温容器（３）との
電位差がダイオードのターンオン電圧以下になるような
値で操作する範囲内においては、電源（６）と超電導コ
イル（１）との間で両アース（り） 、 （４１）間に
廻シ込む電流は発生しない。In the superconducting magnet configured as above,
Diodes (9) connected in antiparallel to each other connect the - point of the superconducting coil (1) and the cryogenic vessel (3), so that the diode connection point of the superconducting coil (1) and the cryogenic vessel (3) are connected. The potential difference generated between them is always about the forward turn-on voltage of the anti-parallel connected diode (q) at extremely low temperatures (this turn-on voltage is about lθ [v] or less, and the voltage drop after turn-on is several CV). (becomes) or less. Usually, the superconducting coil (1) is excited or demagnetized (
When the persistent current switch (k) is turned off, the t source (5
) side voltage is operated at a value such that the potential difference between the connection point of the superconducting coil (1) to which the anti-parallel connected diode (9) is connected and the cryogenic container (3) is equal to or less than the turn-on voltage of the diode. In this case, no current flows between the power supply (6) and the superconducting coil (1) and between the two earths (41).
又、電源（６）と超電導コイル（１）とがコネクタ９Ｃ
ｇ）によって切＃）離される場合の定常運転時（永久電
流スイッチ（コ）はＯＮされる）においては、超電導コ
イル（１）内の電位がダイオードのターンオン電圧以下
に固定されるため、電位浮動による対地放電などは発生
しない。ところで、超電導コイル（１）の超電導破壊な
どＫよる異常電圧発生時においても、アース（ｌＩ）
Ｋ対して超電導コイル（１）の一端の電位が固定されて
いるので、超電導コイル（１）内の各部とアース（ｌＩ
）に対する発生電位差が想定できる。そこでこの電位差
に対応する対地絶縁を施こせば、異常電圧に対拠するこ
とができる。In addition, the power supply (6) and the superconducting coil (1) are connected to the connector 9C.
During steady operation (the persistent current switch (k) is turned on) when the superconducting coil (1) is turned off by g) and released, the potential within the superconducting coil (1) is fixed below the turn-on voltage of the diode, so the potential floats. No ground discharge will occur. By the way, even when an abnormal voltage occurs due to K, such as superconducting breakdown of the superconducting coil (1), the earth (lI)
Since the potential at one end of the superconducting coil (1) is fixed with respect to K, each part in the superconducting coil (1) is connected to the ground (lI
) can be assumed to occur. Therefore, by providing ground insulation that can handle this potential difference, it is possible to protect against abnormal voltages.
なお、この実施例では超電導コイル（１）の上端と極低
温容器（３）とを逆並列接続ダイオードで接続したが、
超電導コイル（１）内の任意の箇所、分割／直列接続超
電導コイルの任意の分割箇所、並列接続超電導コイルの
任意の箇所に逆並列接続ダイオード（９）を接続しても
同様の効果を有する。In addition, in this example, the upper end of the superconducting coil (1) and the cryogenic container (3) were connected with antiparallel connected diodes.
Similar effects can be obtained by connecting an anti-parallel connected diode (9) to any arbitrary location within the superconducting coil (1), any dividing location of the split/series connected superconducting coil, or any arbitrary location of the parallel connected superconducting coil.
接続したことにより、超電導コイルの対地電位差がダイ
オードのターンオン電圧以下に保たれるので、超電導コ
イルに異常に高い対地電圧が加わるのを防止できるとい
う効果と共にコイル側アースと電源側アースとの間に廻
シ込み電流が発生しないという効果を有する。By connecting, the ground potential difference of the superconducting coil is kept below the turn-on voltage of the diode, which has the effect of preventing an abnormally high ground voltage from being applied to the superconducting coil, and also increases the distance between the coil side ground and the power supply side ground. This has the effect that no inflow current is generated.
第１図はこの発明の一実施例を示す結線図、第２図及び
第３図は従来の超電導マグネットを示す結線図である。
図において、（１）は超電導コイル、（コ）は永久電流
スイッチ、（３）は極低温容器、（ｌＩ）はコイル側ア
ース、（Ａ）は電源、（り）は電源側アース、＋ｆｆ）
はコネク’；７ （ｑ）は逆並列接続ダイオードである
。
なお、各図中、同一符号は同−又は相当部分を示す。FIG. 1 is a wiring diagram showing an embodiment of the present invention, and FIGS. 2 and 3 are wiring diagrams showing a conventional superconducting magnet. In the figure, (1) is the superconducting coil, (c) is the persistent current switch, (3) is the cryogenic container, (lI) is the ground on the coil side, (A) is the power supply, (ri) is the ground on the power supply side, +ff)
is a connector'; 7 (q) is an anti-parallel connected diode. In each figure, the same reference numerals indicate the same or corresponding parts.
Claims (3)
容器、 前記超電導コイルを励磁又は消磁しかつアースされてい
る電源、 前記超電導コイルと前記電源とを接続し又は切り離すた
めのコネクタ、及び 前記超電導コイル上の任意の一点と前記極低温容器とを
接続する逆並列接続ダイオード、 を備えたことを特徴とする超電導マグネット。(1) A superconducting coil, a cryogenic container that stores the superconducting coil and is grounded, a power source that excites or demagnetizes the superconducting coil and is grounded, and a device for connecting or disconnecting the superconducting coil and the power source. A superconducting magnet comprising: a connector; and an anti-parallel connection diode connecting an arbitrary point on the superconducting coil to the cryogenic container.
た永久電流スイッチを含むことを特徴とする特許請求の
範囲第１項記載の超電導マグネット。(2) The superconducting magnet according to claim 1, wherein the cryogenic container includes a persistent current switch connected between both ends of the superconducting coil.
ーンオン特性を有することを特徴とする特許請求の範囲
第１項または第２項記載の超電導マグネット。(3) The superconducting magnet according to claim 1 or 2, wherein each of the anti-parallel connected diodes has turn-on characteristics in an extremely low temperature region.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61233192A JPS6388810A (en) | 1986-10-02 | 1986-10-02 | Superconducting magnet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61233192A JPS6388810A (en) | 1986-10-02 | 1986-10-02 | Superconducting magnet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6388810A true JPS6388810A (en) | 1988-04-19 |
Family
ID=16951186
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61233192A Pending JPS6388810A (en) | 1986-10-02 | 1986-10-02 | Superconducting magnet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6388810A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03295280A (en) * | 1990-04-13 | 1991-12-26 | Matsushita Electric Ind Co Ltd | Light emitting diode and manufacture thereof, led array with light emitting diode, and led printer with led array |
| WO2004037081A1 (en) * | 2002-10-24 | 2004-05-06 | Hitachi Medical Corporation | Superconducting magnet device and magnetic resonance imaging system employing it |
-
1986
- 1986-10-02 JP JP61233192A patent/JPS6388810A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03295280A (en) * | 1990-04-13 | 1991-12-26 | Matsushita Electric Ind Co Ltd | Light emitting diode and manufacture thereof, led array with light emitting diode, and led printer with led array |
| WO2004037081A1 (en) * | 2002-10-24 | 2004-05-06 | Hitachi Medical Corporation | Superconducting magnet device and magnetic resonance imaging system employing it |
| US7304478B2 (en) | 2002-10-24 | 2007-12-04 | Hitachi Medical Corporation | Magnetic resonance imaging apparatus provided with means for preventing closed loop circuit formation across and between inside and outside of cryostat |
| CN100413465C (en) * | 2002-10-24 | 2008-08-27 | 株式会社日立医药 | Superconducting magnet device and magnetic resonance imaging system employing it |
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