JPH0345888B2 - - Google Patents
Info
- Publication number
- JPH0345888B2 JPH0345888B2 JP59009714A JP971484A JPH0345888B2 JP H0345888 B2 JPH0345888 B2 JP H0345888B2 JP 59009714 A JP59009714 A JP 59009714A JP 971484 A JP971484 A JP 971484A JP H0345888 B2 JPH0345888 B2 JP H0345888B2
- Authority
- JP
- Japan
- Prior art keywords
- magnetic field
- solenoid
- coil
- current
- bobbin
- 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.)
- Expired - Lifetime
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
- G01R33/389—Field stabilisation, e.g. by field measurements and control means or indirectly by current stabilisation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/06—Electromagnets; Actuators including electromagnets
- H01F7/20—Electromagnets; Actuators including electromagnets without armatures
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Magnetic Resonance Imaging Apparatus (AREA)
Description
【発明の詳細な説明】
本発明は、核磁気共鳴装置に用いられる超伝導
磁石に関し、特に超伝導磁石が発生する磁場の均
一度を改善する装置に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a superconducting magnet used in a nuclear magnetic resonance apparatus, and more particularly to a device for improving the uniformity of a magnetic field generated by a superconducting magnet.
核磁気共鳴装置においては、均一度の高い静磁
場が要求されるが、実用的な大きさの磁石単体で
試料が配置される十分大きな領域にわたつて均一
度の高い磁場を作ることは極めて困難である。そ
のため、静磁場内に補正コイル群を配置し、均一
度の高い領域を拡大せしめることが従来より行わ
れている。 Nuclear magnetic resonance equipment requires a highly homogeneous static magnetic field, but it is extremely difficult to create a highly homogeneous magnetic field over a large enough area for a sample to be placed using a single magnet of a practical size. It is. Therefore, it has been conventional practice to arrange a group of correction coils within a static magnetic field to enlarge a highly uniform region.
第１図ａは、超伝導磁石において、磁場の主軸
（Ｚ軸）方向に補正磁場を発生するために従来用
いられているコイル群を示す。１０は超伝導磁石
の円筒型ソレノイド内に同軸的に挿入される円筒
型組立て体（ボビン）で、その上にリング状コイ
ル１〜７，１′〜７′が巻かれている。各コイル
は、第１図ｂに示すように、ボビン１０の表面に
円周方向に掘られた溝に埋め込むように集中的に
巻かれる。この内直列に接続されたコイルの組
４，４′は１次の軸傾斜補正に、１，５，１′，
５′は２次の軸傾斜補正に２，６，２′，６′は３
次の軸傾斜補正に、３，７，３′，７′は４次の軸
傾斜補正に夫々用いられる。これらのコイルの組
は、夫々電流源９，１０，１１，１２に接続さ
れ、夫々の電流値を加減することにより最適な補
正磁場を得ることができる。これらコイルは、通
常点線で示した超伝導磁石ソレノイドの中心面８
に対して対称になるように配置される。第１図ａ
に示す各リングコイルの中心面８からの距離L1
〜L7は基本的に球面調和関数の解で与えられ、
ボビンの径を与えることによりL1〜L7の値は、
各リングコイルに流すべきアンペアターンの値と
共に一義的に決定される。 FIG. 1a shows a coil group conventionally used in a superconducting magnet to generate a correction magnetic field in the direction of the main axis (Z-axis) of the magnetic field. 10 is a cylindrical assembly (bobbin) inserted coaxially into the cylindrical solenoid of the superconducting magnet, and ring-shaped coils 1-7, 1'-7' are wound thereon. Each coil is wound in a concentrated manner so as to be embedded in a groove circumferentially cut on the surface of the bobbin 10, as shown in FIG. 1b. Of these, coil sets 4, 4' connected in series are used for primary axis tilt correction, 1, 5, 1',
5' is 2, 6, 2', 6' is 3 for secondary axis tilt correction.
In the next shaft tilt correction, 3, 7, 3', and 7' are respectively used for the fourth shaft tilt correction. These coil sets are connected to current sources 9, 10, 11, and 12, respectively, and an optimal correction magnetic field can be obtained by adjusting the respective current values. These coils are usually connected to the center plane 8 of the superconducting magnet solenoid, shown in dotted lines.
arranged symmetrically with respect to Figure 1a
Distance L1 from the center plane 8 of each ring coil shown in
~L7 is basically given by the solution of spherical harmonics,
By giving the diameter of the bobbin, the values of L1 to L7 are:
It is uniquely determined together with the value of ampere turns to be applied to each ring coil.
このような軸傾斜補正磁場発生装置は、(1)比較
的挟い領域しか均一度を高められない、(2)第１図
ｂで示された構造のため放熱性が悪く温度上昇が
激しいため、その放熱効率で最大通電電流（最大
発生磁場）が制約され、大きな補正磁場を発生で
きない、(3)第１図ｂで示された構造のためボビン
の厚みが増し、試料等を配置すべきボビン内部の
有効利用範囲が狭められる、という欠点を持つ。 This type of axial tilt correction magnetic field generator is difficult because (1) uniformity can only be improved in relatively narrow areas, and (2) the structure shown in Figure 1b has poor heat dissipation and causes a rapid temperature rise. (3) Due to the structure shown in Figure 1 b, the thickness of the bobbin increases, and the sample, etc. should be placed in it. This has the disadvantage that the effective range of use inside the bobbin is narrowed.
上記(1)の問題については、特定のコイルの組を
直列接続して特定の次数の補正を受け持たせるの
ではなく、適宜な数のコイルの夫々に独立に電流
を流せるようにしておき、各コイルに流す電流の
比を適宜設定することにより任意の次数の軸傾斜
補正磁場を発生することのできる所謂マトリクス
方式の軸傾斜補正磁場発生装置が提案されてい
る。この提案方式によれば、各コイルの配置に自
由度があり、比較的広い領域の均一度を高めるこ
とができ、前記(1)の問題については改善が期待で
きる。しかしながら、各リングコイルの巻き方は
第１図ｂに示すようなものであり、前述の(2)、(3)
の問題については改善が期待できない。 Regarding problem (1) above, instead of connecting a specific set of coils in series and having them take charge of correction of a specific order, it is possible to make current flow through each of the appropriate number of coils independently. A so-called matrix type axial tilt correction magnetic field generating device has been proposed which can generate an axial tilt correction magnetic field of any order by appropriately setting the ratio of currents flowing through each coil. According to this proposed method, there is a degree of freedom in the arrangement of each coil, and the degree of uniformity in a relatively wide area can be improved, and an improvement can be expected regarding the problem (1) above. However, the winding method of each ring coil is as shown in Figure 1b, and as described in (2) and (3) above.
No improvement can be expected regarding this issue.
本発明は上述した諸点に鑑みてなされたもので
あり、上述した(2)、(3)の問題を解決した軸傾斜補
正磁場発生装置を提供することを目的としてい
る。 The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide an axial tilt correction magnetic field generating device that solves the above-mentioned problems (2) and (3).
本発明の軸傾斜補正磁場発生装置は、円筒型ソ
レノイドの内部に形成される磁場内に円筒型ボビ
ンを挿入し、該ボビンに基準位置を挟んで対称に
複数の区分け境界位置を設定し、各境界位置と境
界位置との間の領域に導線を略均一なピツチで巻
回することにより複数のソレノイドコイルを設
け、該複数のソレノイドコイルの夫々に独立に補
正電流を供給すると共に各ソレノイドコイルへの
電流配分比率を一定に保つたまま各ソレノイドコ
イルへの供給電流を変化させ得る電源手段を設け
たことを特徴としている。以下、図面を用いて本
発明を詳述する。 The axial tilt correction magnetic field generator of the present invention inserts a cylindrical bobbin into a magnetic field formed inside a cylindrical solenoid, sets a plurality of dividing boundary positions symmetrically across a reference position on the bobbin, and sets each division boundary position symmetrically across a reference position. A plurality of solenoid coils are provided by winding a conducting wire at a substantially uniform pitch in the area between the boundary positions, and a correction current is independently supplied to each of the plurality of solenoid coils, and a correction current is supplied to each solenoid coil. The present invention is characterized by the provision of power supply means capable of changing the current supplied to each solenoid coil while keeping the current distribution ratio constant. Hereinafter, the present invention will be explained in detail using the drawings.
第２図ａは本発明を実施した軸傾斜補正磁場発
生装置の一例を示し、同図ｂはその部分断面図を
示す。本発明においては、シムコイルは従来のよ
うに１箇所に集中的に巻かれたリングコイルでは
なく、ある長さを有するソレノイドコイル２１，
２２，２３，２１′，２２′，２３′として均一な
ピツチでボビン１０に巻かれている。ソレノイド
コイル２１と２１′、２２と２２′、２３と２３′
は夫々同じ長さW1、W2、W3を持ち、中心面８
を中心として両側へ向けて２１，２２，２３及び
２１′，２２′，２３′の順で対称に巻かれている。
各ソレノイドコイルには、各ソレノイドコイルの
境界線の部分から第２図ｂに示すように引き出さ
れた引出し線を介して電流源２４〜２９から独立
に補正電流が供給される。 FIG. 2a shows an example of an axial tilt correction magnetic field generator embodying the present invention, and FIG. 2b shows a partial sectional view thereof. In the present invention, the shim coil is not a ring coil wound in one place as in the past, but a solenoid coil 21 having a certain length.
They are wound around the bobbin 10 at uniform pitches as 22, 23, 21', 22', and 23'. Solenoid coils 21 and 21', 22 and 22', 23 and 23'
have the same lengths W1, W2, and W3, respectively, and the central plane 8
It is wound symmetrically in the order of 21, 22, 23 and 21', 22', 23' toward both sides with the center as the center.
Correction currents are independently supplied to each solenoid coil from current sources 24 to 29 via lead wires drawn out from the boundary lines of each solenoid coil as shown in FIG. 2b.
上述の如き構成において、例えばW1＝７mm、
W2＝13mm、W3＝25mmとし、ソレノイドコイル２
１，２１′，２２，２２′，２３，２３′に夫々
4.38ｍＡ、−4.38ｍＡ、2.31ｍＡ、−2.31ｍＡ、19.5
ｍＡ、−19.5ｍＡの電流を各電流源から供給する
ことにより、１次の軸傾斜磁場を発生させること
ができる。この比率を保つたまま各ソレノイドコ
イルの電流を変えれば、１次の軸傾斜磁場の強度
を変化させることができる。又、電流の配分を考
えることにより、２次〜４次の軸傾斜磁場を発生
することができるし、１次の軸傾斜磁場を発生さ
せる電流配分の上に２次あるいは更に高次の軸傾
斜磁場を発生させる電流配分を重畳させれば、１
次と２次あるいは更に高次の軸傾斜磁場を同時に
発生させることができ、この点はマトリクス方式
の特徴がそのまま生かされている。 In the above configuration, for example, W1=7mm,
W2=13mm, W3=25mm, solenoid coil 2
1, 21', 22, 22', 23, 23' respectively
4.38mA, -4.38mA, 2.31mA, -2.31mA, 19.5
By supplying currents of mA and −19.5 mA from each current source, a primary axial gradient magnetic field can be generated. By changing the current in each solenoid coil while maintaining this ratio, the strength of the primary axial gradient magnetic field can be changed. Also, by considering the distribution of current, it is possible to generate a 2nd to 4th order axial gradient magnetic field, and on top of the current distribution that generates a 1st order axial gradient magnetic field, a 2nd or even higher order axial gradient can be generated. If the current distribution that generates the magnetic field is superimposed, 1
It is possible to generate the next and second-order or even higher-order axial gradient magnetic fields simultaneously, and in this point the feature of the matrix method is utilized as is.
更に本発明においては、シムコイルが従来のよ
うに集中的に巻かれているのではなく、ソレノイ
ドコイルとして巻かれているため、ターン数を従
来よりもはるかに多くすることができるし放熱効
率も極めて良好である。従つて、従来よりも大き
な電流をターン数の多いコイルに流すことが可能
になるため、強度の大きな軸傾斜補正磁場を発生
することが可能となる。又、ボビンに溝を掘つて
集中的に埋めこむような必要がないため、装置を
極めて肉薄の円筒状に形成でき、ボビン内部の空
間を広く有効に利用することができる。 Furthermore, in the present invention, the shim coil is not wound in a concentrated manner as in the past, but is wound as a solenoid coil, so the number of turns can be much greater than in the past, and the heat dissipation efficiency is also extremely high. In good condition. Therefore, it becomes possible to flow a larger current through a coil with a larger number of turns than in the past, and it becomes possible to generate a strong axial tilt correction magnetic field. Furthermore, since there is no need to dig a groove in the bobbin and bury it intensively, the device can be formed into an extremely thin cylindrical shape, and the space inside the bobbin can be widely and effectively utilized.
第１図は従来の軸傾斜補正磁場発生装置を説明
するための図、第２図は本発明を実施した軸傾斜
補正磁場発生装置の構成を示す図である。
１０：ボビン、２１〜２３，２１′〜２３′：ソ
レノイドコイル、２４〜２９：電流源。
FIG. 1 is a diagram for explaining a conventional axis tilt correction magnetic field generation device, and FIG. 2 is a diagram showing the configuration of the axis tilt correction magnetic field generation device in which the present invention is implemented. 10: Bobbin, 21-23, 21'-23': Solenoid coil, 24-29: Current source.
Claims (1)
に円筒型ボビンを挿入し、該ボビンに基準位置を
挟んで対称に複数の区分け境界位置を設定し、各
境界位置と境界位置との間の領域に導線を略均一
なピツチで巻回することにより複数のソレノイド
コイルを設け、該複数のソレノイドコイルの夫々
に独立に補正電流を供給すると共に各ソレノイド
コイルへの電流配分比率を一定に保つたまま各ソ
レノイドコイルへの供給電流を変化させ得る電源
手段を設けたことを特徴とする軸傾斜補正磁場発
生装置。1. Insert a cylindrical bobbin into the magnetic field formed inside the cylindrical solenoid, set a plurality of dividing boundary positions symmetrically across the reference position on the bobbin, and define the area between each boundary position. A plurality of solenoid coils are provided by winding a conducting wire at a substantially uniform pitch, and a correction current is supplied to each of the plurality of solenoid coils independently, while the current distribution ratio to each solenoid coil is kept constant. An axial gradient correction magnetic field generating device characterized in that it is provided with a power supply means that can change the current supplied to each solenoid coil.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59009714A JPS60153111A (en) | 1984-01-23 | 1984-01-23 | Magnetic-field uniformity correcting device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59009714A JPS60153111A (en) | 1984-01-23 | 1984-01-23 | Magnetic-field uniformity correcting device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60153111A JPS60153111A (en) | 1985-08-12 |
| JPH0345888B2 true JPH0345888B2 (en) | 1991-07-12 |
Family
ID=11727928
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59009714A Granted JPS60153111A (en) | 1984-01-23 | 1984-01-23 | Magnetic-field uniformity correcting device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60153111A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0236789A1 (en) * | 1986-02-28 | 1987-09-16 | Siemens Aktiengesellschaft | Non-orthogonal Shim coil system for the correction of magnetic-field inhomogeneities in nuclear magnetic resonance apparatuses |
| US8487729B2 (en) * | 2009-02-02 | 2013-07-16 | Northrop Grumman Guidance & Electronics | Magnetic solenoid for generating a substantially uniform magnetic field |
| DE102018200098B3 (en) | 2018-01-04 | 2019-01-03 | Bruker Biospin Ag | NMR shim system, coil body for a shim system and method for producing a shim system |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57172238A (en) * | 1981-04-17 | 1982-10-23 | Hitachi Ltd | Magnetic field correcting device |
-
1984
- 1984-01-23 JP JP59009714A patent/JPS60153111A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60153111A (en) | 1985-08-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |