WO2004095046A1

WO2004095046A1 - Nuclear magnetic resonance analyzer and magnet for nuclear magnetic resonance apparatus

Info

Publication number: WO2004095046A1
Application number: PCT/JP2004/002908
Authority: WO
Inventors: Tomomi Kikuta; Tsuyoshi Wakuda; Koji Maki; Shigeru Kakugawa
Original assignee: Hitachi, Ltd.
Priority date: 2003-04-24
Filing date: 2004-03-05
Publication date: 2004-11-04
Also published as: JP4034224B2; JP2004325252A

Abstract

3. A magnetic resonance apparatus comprising a superconducting coil, a cryogenic container for containing the superconducting coil and refrigerant for cooling it, a permanent current switch connected with the superconducting coil, a space surrounded by the superconducting coil and being inserted with a sample to be measured, and a probe coil disposed in the center of a magnetic field within that space and receiving the sample internally, the superconducting coil comprising a first coil group constituted of a plurality of coils wound around some axis as a common central axis and a second coil group constituted of a plurality of coils wound around that central axis as a common central axis, with the first coil group and the second coil group being disposed oppositely across some space, characterized in that at least one coil, out of the coils constituting the first and second coil groups other than the coil having a largest winding radius, is a reverse current coil which is defined as being supplied with a current in the direction for generating a magnetic field oppositely to a main magnetic field.

Description

Description Nuclear magnetic resonance analyzer and magnet for nuclear magnetic resonance equipment

The present invention relates to a nuclear magnetic resonance analyzer for analyzing organic molecules such as proteins, substrates interacting with proteins, ligands, and the like, and a magnet for a nuclear magnetic resonance apparatus for generating a uniform magnetic field. Background art

FIG. 14 is a schematic cross-sectional view of a conventional NMR (Nuclear Magnetic Resonance) analyzer.

The superconducting coils 81, 82, 83, and 84 are made of a material with a higher superconducting critical magnetic field as the inside is closer to the sample. The superconducting coils 81, 82, 83, and 84 constituting the superconducting magnet are wound in a solenoid shape around a vertical axis, and are connected by superconducting connections 89, respectively. Is protected. The superconducting magnet is maintained in a permanent current mode by a permanent current switch 91.

Furthermore, the superconducting magnet is constituted by a low-temperature container that is immersed in liquid helium 87 and is kept at a low temperature, and has a double structure in which the outside is covered with liquid nitrogen 88, thereby saving helium consumption. This cryogenic container is supported by vibration-proof support legs 86 so that external vibrations are not transmitted into the container. A protein sample solution sample 92 is inserted into the center of the magnetic field from the top of the device and placed vertically. ing. The probe is inserted into the center of the magnetic field from the lower part of the apparatus, and a copper saddle-shaped or birdcage-shaped probe coil 85 kept at room temperature is used. It is.

In this way, a vertical magnetic field is applied to the sample placed in the vertical direction by the solenoid type superconducting magnet, and the force of detecting the NMR signal using the saddle type or bird cage type probe coil 85. , A conventional NMR analyzer.

Analytical methods for organic substances using NMR (nuclear magnetic resonance) have been making rapid progress in recent years. In particular, the combination with powerful superconducting magnet technology has made it possible to efficiently analyze the structure of organic compounds such as proteins having complex molecular structures at the atomic level.

The subject of the present invention is an NMR spectrometer required for analyzing the atomic level structure and interaction of protein molecules in an aqueous solution in which a trace amount of protein is dissolved. In medical MRI diagnostic imaging equipment for tomography of the human body that requires millimeter-level image resolution, the magnetic field strength is higher by at least one order of magnitude, the magnetic field uniformity is four orders of magnitude, and the stability is three orders of magnitude higher. It is a special type of energy spectroscopy that requires a completely different design technology and device manufacturing technology.

Details of the conventional high-resolution nuclear magnetic resonance spectrometer are described in Yoji Arata, "Protein NMRJ Kyoritsu Shuppan, 1996 (Non-Patent Document 1). A typical example of using NMR for protein analysis. As a recent invention related to a typical device configuration, Japanese Patent Application Laid-Open No. 2000-147082 (Patent Document 1) discloses a typical configuration of a multilayer air-core solenoid coil as an invention relating to a superconducting magnet. As an invention related to the signal detection technology, US Pat. No. 6,121,776 (Tokukura No. 2), which discloses a birdcage-type superconducting detection coil, and a signal detection technology using a conventional saddle-type coil or birdcage-type coil. As disclosed examples, Japanese Patent Application Laid-Open No. 2000-266830 (Patent Document 3) and Japanese Patent Application Laid-Open No. 6-237912 (Patent Document 4) are disclosed.

According to these reports, conventional sensitive NMR analysis for protein analysis The device uses a superconducting magnet device composed of a combination of solenoid coils that generate a vertical magnetic field, irradiates the sample with an electromagnetic wave of 400 to 900 MHz, and converts the resonance wave emitted from the sample into a saddle or bird cage type. Detection is performed using the detection coil.

In addition, as in the example of Patent Document 2, in order to reduce thermal noise at the time of reception, there are cases where a device cooled at low temperature is used to improve the SZN sensitivity ratio. .

Historically, high-sensitivity NMR systems have improved sensitivity by increasing the central magnetic field strength of the superconducting magnet, while keeping the basic configuration of the system, such as the antenna and magnet, the same.

Therefore, the highest NMR measurement sensitivity reported to date can be obtained with a 900 MHz NMR apparatus.For example, as shown in Fig. 8, a large superconducting magnet with a central magnetic field of 21.1 Tesla is used. The basic configuration of the device is not different from the prior art as in Patent Document 1 described above. In protein analysis using solutions, improving the central magnetic field has the effect of improving sensitivity and clarifying the separation of chemical shifts.

As described in Yuji Arata's Yoji Arata, NMR book J2000, Maruzen, p326 (Patent Document 2), the sensitivity improvement effect of the detection coil shape, if a solenoid coil is conventionally used as the detection coil, It has been known that there are various advantages compared to the mold or bird cage type, for example, it is superior in terms of impedance controllability, filling factor, RF magnetic field efficiency, etc. .

According to the authors, the conventional superconducting magnet configuration requires a sample placed vertically with respect to the magnetic field when importance is placed on the measurement of proteins dissolved in a small amount in an aqueous solution. It is practically impossible to wrap a solenoid coil around a tube and it is not commonly used. In particular, exceptionally, It may be used only when measuring with high sensitivity using a sample solution, and a method of measuring with a special probe using a specially designed micro sample tube has been known.

As a special case, a method of magnetizing a high-temperature superconducting bulk magnet in a horizontal direction and detecting an NMR signal with a solenoid coil has recently been disclosed in Japanese Patent Application Laid-Open No. 11-24881◦ (Patent Document 5). Has been devised.

Also, Japanese Patent Application Laid-Open No. 7-240310 (Patent Document 6) discloses a method of configuring a superconducting magnet and a cooling vessel suitable for general NMR applications for removing restrictions on the ceiling height of the apparatus. However, it is not known how to improve the detection sensitivity necessary for protein analysis, nor how to deal with the magnetic field homogeneity and the time stability of the magnetic field.

In recent years, with the growing need for protein research, the need to analyze samples with low solubility of proteins in water has increased, and it has been necessary to improve the measurement sensitivity of NMR. To adapt NMR analyzers to these needs, it is necessary to improve the measurement sensitivity while maintaining the same sample space as before, and to ensure the stability of the superconducting magnetic field during long data integration times. Is also mandatory.

Improvement of measurement sensitivity is not only shortening the measurement time but also reducing the amount of sample as long as the sample has the same level of solubility. .

Therefore, NMR analyzers used for protein analysis require extremely superior detection sensitivity and stability compared to conventional NMR analyzers, and are accurate over a long period of one week or more. Stable NMR signal detection is required. This is because if the magnetic field fluctuates during the measurement, the peak of the NMR signal shifts.In particular, in the measurement of the interaction, the peak shift is due to the interaction or due to the instability of the magnetic field. What to do Is no longer possible.

In addition, if the magnetic field is non-uniform, desired peaks overlap, which causes problems such as difficulty in determining the interaction. Therefore, it is important to note that future NMR techniques for the various analyzes of proteins will require new technology development beyond the simple extension of conventional general NMR analyzers. There is a need.

As an example, the specification of the magnetic field uniformity of a general NMR instrument is 0.01 ppm in the sample space and 0.01 ppm / h in the time stability. Converting this to 600 MHz proton NMR for general use gives a 6 Hz tolerance.

In the case of the protein interaction analysis described above, a space of at least 1.0 Hz or less and a time resolution are required, and preferably 0.5 Hz or less.

It is necessary to optimally configure the superconducting magnet and the detection coil in a way that can achieve the uniformity of the magnetic field and the temporal stability of the magnetic field. Therefore, the performance of NMR spectrometers generally used in the past is insufficient, and stability and magnetic field homogeneity higher by one order of magnitude or more than before are required.

In the conventional technology, the sensitivity has been improved mainly by improving the magnetic field strength, so the equipment has become larger, and due to the problems of the leakage magnetic field and the floor strength, a special building is required. occured. In addition, there were problems such as an increase in the cost of superconducting magnets. In addition, the sensitivity improvement by this method is limited by the critical magnetic field of the superconducting material, and almost reaches the upper limit of 21 Tesla (T). To improve sensitivity further, a new method that does not rely on the magnetic field strength is used. Techniques for improving detection sensitivity by means have been desired.

As described above, the high-sensitivity measurement method using a solenoid coil can be used with a very small amount of a special sample tube and a special detection probe. Could not be applied to Also, as in the example of Patent Document 5, in the method of generating a magnetic field in the horizontal direction by a strong magnet and detecting an NMR signal by a solenoid coil, a magnetic field of less than 1 OT is generated on the surface of the high-temperature superconductor. The magnetic field of the sample part is only about several T at most, and a magnetic field of 11 T or more required for protein analysis, preferably 14.1 T or more, is generated in the desired sample space. This was not possible with this method.

Also, with this method, it was practically difficult to achieve the time stability of less than 1.0 Hz / hour required for protein analysis due to the effect of magnetic flux creep of high-temperature superconductors.

Regarding the magnetic field homogeneity required for protein analysis, achieving a magnetic field homogeneity within 1.0 OHz at the proton nuclear magnetic resonance frequency in a space of 1 Qmm in diameter and 20 mm in length requires a high-temperature superconducting bulge. This was difficult due to the heterogeneity caused by the material manufacturing process.

As described above, while the conventional technology has been required to develop a breakthrough technology to meet the needs of protein analysis, now that the limit of sensitivity improvement by magnetic fields has been reached, A new solution was sought.

Efficient and high-precision analysis of the interaction between proteins and small molecules such as substrates and ligands in solutions, for which needs are expected to increase in the future, is empirically determined to be 600-900 MHz and a central magnetic field. Therefore, it is desirable to be able to measure with an appropriate sample amount at about 14 to 21 T, and it is desired to improve the measurement sensitivity and to increase the throughput from the current state.

In general, a device operating at 800 MHz or higher is operated under reduced pressure of 4.2K liquid helium and supercooled to 1.8K in order to utilize the superconductivity to the utmost. For this reason, in addition to increasing the complexity of operation of the apparatus, maintenance is also difficult. In addition, since the size of the magnet device is large, the leakage magnetic field is large. Need things. In particular, from the viewpoint of installability of the device, in the conventional method, the leakage magnetic field increases in the vertical direction as the center magnetic field increases. For this reason, for example, in a 900 MHz class device, a leakage magnetic field of as much as 5 m is generated in the height direction, and a building having a higher ceiling height is required, and there is a problem that the building cost increases. As described in I EEE. Transactions on Applied Superconductivity, Vol. 11, No. 1, p2438 (Non-Patent Document 3), only the size of the magnet part has a width of 1 86 m and a height of several meters. Become. Disclosure of the invention

The present invention relates to: 3. a superconducting coil, a low-temperature container containing the superconducting coil and a refrigerant for cooling the superconducting coil, a permanent current switch connected to the superconducting coil, and a measurement target surrounded by the superconducting coil. It has a space in which a sample is inserted, and a probe coil installed in the center of the magnetic field in the space and having the sample installed therein. The superconducting coil is wound so that a certain axis becomes a common central axis. A first coil group composed of a plurality of coils, and a second coil group composed of a plurality of coils wound around the central axis as a common central axis. The second coil group is disposed so as to face each other with a certain space therebetween.If a coil that is energized in a direction that generates a magnetic field in a direction opposite to the main magnetic field is defined as a reverse current coil, the first coil group and the second coil group Configure the second coil group The present invention provides a nuclear magnetic resonance magnet characterized in that at least one coil is a reverse current coil except for the coil having the largest winding radius among the coils having the maximum winding radius. A new NMR analysis method that uses a sample tube with a diameter of approximately 30 mm and fills the sample solution with a height of approximately 30 mm, increasing the measurement sensitivity of NMR signals by about 40% or more at about 600 MHz (14.1 T). An object of the present invention is to provide a superconducting magnet which can constitute a device. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic sectional view of an NMR apparatus using the split magnet of the present invention.

FIG. 2 is a coordinate diagram showing a positional relationship between a current and a magnetic field.

Fig. 3 is a coordinate diagram showing the relationship between the angle of the coil and the z-axis.

FIG. 4 is a perspective view related to the arrangement of the coils of the split magnet according to the second embodiment.

FIG. 5 is a sectional view of an arrangement configuration of coils of a split magnet according to a third embodiment.

FIG. 6 is a cross-sectional view relating to the coil arrangement of the split magnet according to the fourth embodiment.

FIG. 7 is a cross-sectional view illustrating a coil arrangement of a split magnet according to a fifth embodiment.

FIG. 8 is a sectional view of a coil arrangement configuration of a split magnet according to a sixth embodiment.

FIG. 9 is a sectional view of a coil arrangement configuration of the split magnet according to the seventh embodiment.

FIG. 10 is a cross-sectional view of a coil arrangement of a split type magnet and a coil arrangement for leakage magnetic field shielding according to an eighth embodiment.

FIG. 11 is a cross-sectional view of a coil arrangement of a split type magnet and a ferromagnetic material for leakage magnetic field shielding according to a ninth embodiment.

FIG. 12 is a sectional view of the split type magnet coil, the leakage magnetic field shielding ferromagnetic material, and the leakage magnetic field shielding coil arrangement according to the tenth embodiment. FIG. 13 is a cross-sectional view of the coil arrangement of the split magnet, the ferromagnetic material for the leakage magnetic field shield, and the coil arrangement for the leakage magnetic field shield according to Example 11; FIG. 14 is a schematic sectional view of a conventional NMR apparatus.

FIG. 15 is a perspective view of a coil wound around a pobin of the split magnet according to the second embodiment.

FIG. 16 is a sectional view of a coil arrangement of the split magnet according to the second embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

This high-sensitivity NMR apparatus needs to be configured not with a conventional solenoid magnet but with a pair of split magnets divided into right and left with a facing space. As described above, a magnet for an NMR apparatus needs to generate a very uniform magnetic field in the order of ppb in the space where the sample is measured.

With a 14.1 T class high-field split magnet, it is difficult to obtain magnetic field uniformity compared to a solenoid magnet, and no method has been found to achieve this magnetic field uniformity. This is because, in a split magnet, the facing space is provided between the left and right magnets, which limits the space available for generating a magnetic field, and is disadvantageous for generating a magnetic field and achieving uniformity.

In the present invention, the operating temperature of the system is not set to 4.2K. It is also possible to aim for the ultimate performance by applying the present invention.In some applications, the conventional magnetic field limit of 21, 1, that is, operation at 1.8 MHz at 900 MHz is possible. There may be. In this case, the sensitivity can be improved by 40% compared to the conventional method, and the detection sensitivity limit due to the magnetic field strength, which was impossible in the past, can be greatly reduced.

The present inventors have studied the problems common to current nuclear magnetic resonance apparatuses and the countermeasures therefor.

In the current NMR system, a solution sample is placed in the center of a multilayer air-core solenoid coil with excellent magnetic field uniformity, and a saddle or bird It has been developed by a method of detecting with a cage type antenna. Historically, as NMR has progressed from low magnetic fields below 400 MHz due to advances in measurement technology and analysis methods, measurement sensitivity has been improved by increasing the central magnetic field while maintaining this basic format. .

Recently, an example of using a superconducting birdcage antenna to reduce thermal noise has been reported.

The inventors of the present invention have intensively studied a method of significantly increasing the signal strength while maintaining the same magnetic field strength. As a result, they found that the new method described below can solve this problem.

The point is that a solution space with a diameter of 5 to 1 Omm and a height of 20 mm

A magnetic field of 400MHz or more suitable for MR, preferably <6.0 to 900MHz, and the detection coil can be used as it is for a sample tube for ordinary NMR research.

~ 1 Omm 0 X The sensitivity is improved by applying a solenoid type detection coil with a height of about 20 mm.

In principle, at least 1.4 (2) times higher sensitivity can be expected due to the difference in the shape factors of the detection coils, and further improvements can be expected due to other factors, so the data integration time is less than 1/2. Can be shortened to The solution sample is placed in a sample tube with a diameter of 5 to 1 Omm at a height of about 20 to 30 mm and inserted vertically from above. To detect NMR signals with high sensitivity using a solenoid coil with a vertical axis as the winding axis, the magnetic field generated by the superconducting magnet is arranged horizontally, and a solution sample that can be easily attached and detached is arranged at the center of the magnetic field. There is a need.

Therefore, the configuration of the superconducting magnet is different from a conventional simple solenoid magnet, and it is necessary to configure the superconducting magnet with a pair of split magnets divided into right and left.

As described above, a magnet for NMR equipment needs to generate a very uniform magnetic field on the order of ppb in the space where the sample is measured. No method has been found in U.S. Pat.

In the present invention, two sets of coil groups consisting of a plurality of coils are arranged at opposing split magnets at a certain interval, and at least one coil that carries a current in a direction opposite to the direction in which the main magnetic field is generated is provided. By providing it near the position where the main magnetic field is generated, the disadvantage due to the spatial limitation of the split magnet is eliminated, and a uniform magnetic field equivalent to that of a conventional solenoid magnet is obtained.

Hereinafter, a method of generating a uniform magnetic field will be described. Polar coordinate (r, theta, 0) represented by the magnetic field B _z in the z-direction of a space, generally r, theta, expressed by [Equation 1] as a function of ų.

[Equation 1]

In _{_{_{^{B 2 = r n P n m}}}} (cos ^) (A n m sinm0 + B n m cosm0) ... [Equation 1] Thus magnetic field shape obtained by multiplying the coefficients in the function r ⁿ P _n ^m which is determined by the position expressed. η is the sum of 0 to ∞, and the coefficient when π = 0 is the 0th order coefficient, η

The coefficient when = 2 is defined as the second-order coefficient and used below.

In the following, the properties of the π-order coefficient of the magnetic field generated by the ring current of magnitude I are explained.

Figure 2 shows a coordinate diagram of the current and the magnetic field. It is assumed that a circular current I in a direction in which a magnetic field is generated in the z-axis direction, that is, a plus direction, is flowing through the conductor 11 at a distance f from the origin and an angle between the f-axis and the z-axis. Here, the current that creates a magnetic field in the z-axis direction is called the plus current, and the opposite current is called the minus current.

When the current is flowing through the coil, not the ring current, the center axis of the coil is assumed to be approximately the z-axis, the distance from the origin to the coil center is f, and the straight line connecting the coil center and the origin is the center axis. The angle between Hereinafter, the angle between the straight line connecting the coil center and the origin and the center axis of the coil is defined as. When the magnetic field created by this circular current at the position represented by the curved coordinates (r, Θ, ø) is obtained in the curved coordinate system, The axially symmetric component of the magnetic field B _z is expressed by the following equation. [Equation 2]

P ^x _{n + 1} (cos) P _n (cos0)

I

··· [Equation 2] As shown in the above equation, the magnetic field is represented by the sum of n. Let this be the nth order magnetic field, respectively. Hereinafter, the magnetic field as are all B _z, write an order n B _z and B _n. The central magnetic field required for NMR measurement is B 0, and the other magnetic field B _π is called the η-order irregular magnetic field because it is a magnetic field that disturbs the uniformity.

The part of _{η η} independent of と

[Equation 3]

μ olsinct P ¹ _Ji +! (cos a)

An =… (Equation 3)

2 f ^{n + 1} , which is called the n-th order expansion coefficient. When n = 2, the second order expansion coefficient A ₂ is A ₂ ocP ₃ ¹ (GOSQ.

^{Pa 1 (cosa) = (3/2} 1 -cos than ² a ^(5cos a- 1) ··· [Equation 4], ₃ [rho 0 rather cos <1 (become GOSQ = 0 is, or <arccos (1 / ^/ V "5) = 63.43 °. The sign of the second order expansion coefficient is determined by the angle at which the positive current is arranged, and A ₂ > 0 and 63.43 ° at 0 and 63.43 ° ( At ττ / 2), A ₂ becomes 0.

FIG. 3 is a coordinate diagram showing the relationship between the angle of the coil and the Z axis. In Fig. 3, 15 is the coil, and the straight line 13 is the angle with the z axis. Qf2 = arccos (1 / V "5) = 63.43 ° represents a straight line.

Similarly the coefficient A ₄ of fourth order field A ₄ ocP ₅ ¹ (cos), and the sign of A ₄ is Decisive round the sign of P 5 ¹ (cos).

[Equation 5]

P _B ¹ (cosa) = (l 5/8> 1 -cos ² a (2 lcos ^{4 a-} 14 cos ² a + 1)

... than [Equation 5], rather than 0 rather cos "! In the P ₅ ¹

or = arccosV "((7-l-2) V" 7)) / 21 = 40.09 °, 73.43 °.

Thus the fourth order exhibition ϋ coefficient code is 0 <shed <40.09 ° in Α _4> 0,40.09. At 73.43 °, Α ₄ <0, and at 90 ° 73.43 °, Α ₄ > 〇.

In Figure 3, the angle 1 that the straight line 12 makes with the ζ axis is

»1 = arccos ^ ((7 + 2) V" 7)) / 21 = 40.09 ° represents a straight line, and the angle 3 that the straight line 14 makes with the z-axis is

^ 3 = arccosV "((7-2) ^ 7)) X21 = 73.43 ° represents a straight line.In Fig. 3, the explanation of the irregular magnetic field created by the coil 15 placed at an angle from the z axis I do.

The coil 15 is assumed to be energized in the plus direction, and creates a magnetic field in the direction of the main magnetic field for NMR measurement. The angle between the z-axis and the straight line 12 is or 1, the angle between the z-axis and the straight line 13 is 2, and the angle between the z-axis and the straight line 14 is or 3.

The straight line 13 indicates the position where the second-order irregular magnetic field created by the coil 15 having a positive current becomes zero.In the region between the straight line 13 and the z-axis, the second-order irregular magnetic field becomes positive, In the region between 13 and the X axis, the second-order irregular magnetic field becomes negative. Lines 12 and 14 indicate the positions where the fourth-order irregular magnetic field created by the coil 15 having a positive current becomes zero, and the region sandwiched between the z-axis and the line 12, and The fourth-order irregular magnetic field is positive in the region between the straight line 14 and the x-axis, and the fourth-order irregular magnetic field is negative in the region between the straight lines 12 and 14.

As described above, the split-type superconducting magnet is more difficult to obtain the magnetic field homogeneity required for protein structure analysis than the conventional solenoid-type superconducting magnet.

Because a gap is provided across the X axis, a coil energized in the plus direction is placed in the space between the straight line 13 and the X axis, and the resulting negative secondary magnetic field component generation amount, Also, the amount of the positive fourth-order magnetic field component obtained by arranging the coil energized in the plus direction in the space between the straight line 14 and the X axis is limited.

Therefore, a negative secondary magnetic field component is generated when a coil energized in the plus direction is generated, and a negative fourth magnetic field component is generated when a coil energized in the positive direction is arranged. By placing a coil that is energized in the direction, a negative second-order magnetic field component and a positive fourth-order magnetic field component are generated.

As a result, even in the split type superconducting magnet, it is possible to generate a very uniform magnetic field equal to or more than that of the conventional multilayer solenoid.

Next, the optimal arrangement of each coil will be described. In order to obtain the uniformity of the magnetic field required for protein analysis while maintaining the central magnetic field, a central magnetic field is generated by a coil constituting the relatively outer side of the coil layer. It is efficient to correct the magnetic field using a coil that forms a relatively inner part of the coil layer.

This is because, from the above [Equation 1], since the higher-order magnetic field becomes larger as the distance f between the origin and the coil center becomes smaller, it is possible to correct even a coil having a small amount of current. In addition, by dividing the coil layer near the center axis into multiple coils, the direction and magnitude of coil current, coil arrangement, etc. can be adjusted in a region where f is relatively small. Since the degree of freedom of the combination of the magnetic field increases, the magnetic field can be adjusted more accurately with a small amount of current. As the number of coils increases, the time and effort required for fabrication increases, and the cost also increases.

Next, consider a coil arrangement that can reduce the number of coils while obtaining the uniformity of the magnetic field required for protein analysis.

According to the above [Equation 1], the coil is preferably arranged at a position somewhat away from the origin force so as not to generate an extra high-order magnetic field. In order to keep a certain distance from the origin to the coil, when viewed on a cross-section passing through the center axis of the coil, the center of the cross-section of the coil that is energized in the minus direction will have a circular or elliptical shape. Deploy.

From [Equation 1], the magnetic field has a property that depends on the straight line connecting the origin and the coil center, and the angle α between the straight line and the z-axis. Angle α from ζ axis α force If there are multiple coils placed at approximately the same position, the magnetic field generated by those coils is determined only by the combination of the distance f from the origin, so the magnetic field generated by the combination of coils Adjustment becomes easier. As a result, when viewed on a cross-section passing through the center axis of the coil, the center of the cross-section of the coil energized in the negative direction is arranged in a circle or an ellipse, and the outside of the circle or the ellipse in the radial direction, or Arrange so that the cross section of the coil that is energized in the positive direction comes to a position that has the same degree as the coil that is energized in the negative direction on the outside and the inside. '' As a result, when viewed in a cross-section passing through the central axis, the coil was energized in the positive or negative direction outside or inside and outside the circle or ellipse where the cross-section of the coil was energized in the negative direction. By arranging the cross section of the coil in a circular or elliptical shape, it becomes possible to efficiently cancel high-order magnetic fields with a small number of coils.

In addition, a coil that is energized in the negative direction creates a magnetic field that is opposite to the central magnetic field. Therefore, if a coil that is energized in the negative direction is used to obtain uniformity, the main magnetic field for NMR measurement is canceled, and a positive current coil is used to capture it. The size of the magnet must be increased, which increases the size of the entire magnet.

Using a coil that is energized in the negative direction, it obtains the homogeneity required for protein structural analysis, and minimizes the magnetic field in the opposite direction to the central magnetic field created by the coil that is energized in the negative direction. In order to reduce the size of the coil, the coils energized in the minus direction are concentrated near the position where the magnetic field is generated.

This will be described using equation (1). Distance from the origin f, and the magnetic field of zero order in the z direction in which the coil is energized to the current one I generated, the magnetic field B ₂ of the second-order z-direction, respectively Re its Re is expressed by the following equation.

[Equation 6]

Bo = — (z. I sina> / 2) P! ^ Cos) P _o (cos0) (1 / f) "· [Equation 6]

B ₂ =-(O Isina) / 2) P ₃ ¹ (cos a) P ₃ (cos) (r Vf ³ )

... [Equation 7] Here, the coil of the distance 2f from the origin to generate the same second-order magnetic field B _2. The amount of current required for that is

[Equation 7]

— (/ I. Sina) / 2) P ₃ ¹ (cosa) P ₂ (cos0> (r ² / <2i) ³ )

=-(jti ₀ Isina) / 2) P ₃ ¹ (cosa) P ₂ (cos0) (rf ⁸ )

… [Equation 8]

I '= 8 I, which means that when the distance from the origin is doubled, eight times the current is needed to create the same magnetic field B ₂ . At this time, a magnetic field B in the opposite direction to the central magnetic field created by this coil. ' [Equation 8]

B ₀ '= — (.8 Isina) / 2) P ₁ ¹ (cos) P _o (cos0) (1/2 f) = 4Β _β

… [Equation 9], and the magnitude of the magnetic field in the direction opposite to the central magnetic field created by the coil whose distance from the origin is 2f is 4 times the magnitude of the magnetic field in the direction opposite to the central magnetic field created by the coil at the distance f from the origin. Double.

Therefore, in order to reduce the amount of current of the coil that is energized in the minus direction, and to reduce the magnetic field in the direction opposite to the central magnetic field and reduce the size of the entire magnet, the coil that is energized in the minus direction should be as close to the origin as possible. Place it near.

In order to generate a strong magnetic field of 1 OT or more with a uniformity of the order of 1 ppb in a space with a coil diameter of about 1 cm to 2 cm as described above, it is most suitable due to the properties of the magnetic field. It is suitable for the coil arrangement of the magnet for nuclear magnetic resonance.

(Example 1)

FIG. 1 is a schematic sectional view of an NMR apparatus using a split type magnet. A solenoid type superconducting magnet 1 is placed in the horizontal direction, inserted from the top of the apparatus, and a magnetic field is applied to the solution sample 9 of the protein sample placed in the vertical direction from the lateral direction.

For the detection of the NMR signal, a copper solenoid type probe coil 8 kept at room temperature or a Y type or MgB ₂ solenoid type probe coil 8 cooled to 5 to 20K is used.

The superconducting magnet 1 is maintained in the persistent current mode by the persistent current switch 5, and the respective coils forming the superconducting magnet 1 are connected by the superconducting connection 6 and protected by the protection circuit 4 from burning out during quenching. Protected. The superconducting magnet 1 is immersed in liquid helium 3 as a cooling means, is kept at a low temperature, and has a double structure covered with liquid nitrogen 2 and is constituted by a low-temperature container for saving helium consumption. In addition, the anti-vibration support leg 7 prevents external vibration from being transmitted to the superconducting magnet 1.

(Example 21

FIG. 15 is a perspective view of a coil wound around a bobbin of the split magnet according to the present embodiment. The superconducting coils 93 to 100 are wound around pobins, respectively. The space in the center of the pobin is called a bore, and a small-diameter pobin is placed in the pore of a large-diameter pobin, and a nested structure with a smaller-diameter pobin is placed in the pore. The coils maintain their position. FIG. 4 is a perspective view showing a superconducting coil without a pobin.

A group of a plurality of superconducting coils 16, 17, 18, 19, 20, 21, and 22, wound around the center axis 23 of the magnet substantially at the center, is separated by a gap. They are arranged so as to be almost mirror-symmetric. A uniform transverse magnetic field is formed at the intersection of the gap and the pore.

FIG. 16 is a cross-sectional view taken along the center axis of FIG. The superconducting coils 107 and 108 are arranged such that the windings overlap in the central axis direction. The superconducting coils 20, 22 and the reverse current coils that form this magnet.

By using the reverse current coil in this way, a uniform magnetic field can be obtained efficiently, the number of coils in the entire magnet can be reduced, and the size of each coil can be reduced. Equipment can be provided at low cost.

When the coil section is viewed on a section passing through the center axis 23 of the magnet, the angle between the center axis and the straight line connecting the center of the section of the superconducting coil and the origin is defined as α. 2 or 1 is located at 2 position and another superconducting coil creates a secondary irregular magnetic field or other superconducting It cancels out the second and fourth order magnetic fields created by the coil.

With such a configuration, it is possible to generate a very uniform magnetic field equal to or more than that of the conventional solenoid type magnet even with the split type magnet. In the first and second embodiments, an outline of a magnet-based NMR system using the split coil configuration according to the present invention and a magnet are shown. In the following example

An embodiment in which only a method of configuring a superconducting coil in an NMR system is disclosed using a cross-sectional view passing through a center axis of a magnet.

(Example 3)

FIG. 5 is a schematic cross-sectional view showing the arrangement of the cross-section of the superconducting coil as viewed on a cross-section passing through the central axis in the present embodiment.

The superconducting coils 24 to 34 and 24 'to 34' are arranged substantially concentrically with respect to the central axis 35 of the horizontal magnet, and the left and right coil groups are wound around a substantially common central axis, and It is arranged almost mirror-symmetrical with respect to the central plane.

Two or more superconducting coils 28 to 34 (28 'to 34') are arranged so that the coils close to the central axis of the left and right superconducting coil groups overlap each other in the central axis direction. In this way, a coil located at a position close to the uniform magnetic field space is finely divided and its position and size are adjusted, so that a uniform magnetic field can be easily obtained. The superconducting coils 32 and 34 are reverse current coils, which are arranged at positions of or 2 and 1 and α, respectively, so that the second-order irregular magnetic field generated by the other superconducting coils or other It cancels out the second and fourth order magnetic fields created by the superconducting coil.

At least one of the superconducting coils 27, 28, 29, 30, and 31 is arranged in a region of <1, and cancels the fourth-order irregular magnetic field created by the other superconducting coils.

This makes it possible to efficiently cancel the irregular magnetic field of the entire magnet, A uniform magnetic field is formed at the order of 1 ppb at the center of the nucleic acid, which makes it possible to clearly measure weak nuclear magnetic resonance signals, enabling the analysis of protein structure.

(Example 4)

FIG. 6 is a schematic cross-sectional view showing the arrangement of the cross-section of the superconducting coil as viewed on a cross-section passing through the center axis in the present embodiment.

The superconducting coillets 36 to 43 and 36 'to 43' are arranged almost concentrically with respect to the horizontal center axis, and the left and right coil groups are wound around a substantially common center axis. They are arranged almost mirror-symmetric with respect to the plane.

The coils close to the central axis of the left and right superconducting coil groups are arranged so that the windings overlap in the central axis direction, and each is composed of two or more superconducting coils 39 to 43. The superconducting coils 39, 40 are divided in the direction of the central axis in order to easily obtain a uniform magnetic field.

Of these, superconducting coils 41 and 42 are reverse current coils, which are located at or or 2 or 1 <<2, respectively, and the secondary irregular magnetic field created by other superconducting coils or other superconducting coils It cancels out the second and fourth order magnetic fields created by the coil.

In addition, at least one of the superconducting coils 39, 40, and 43 is arranged in the first region, and cancels the fourth-order irregular magnetic field created by the other superconducting coils. Efficient cancellation is possible, and a uniform magnetic field of 1 ppb order is formed at the center of the coil.

Further, when viewed in a cross section passing through the center axis of the coil, the cross sections of the coils 41, 41 and 42, 42 are arranged so as to overlap a common circular or elliptical arc. By maintaining a certain distance from the magnetic field generation position in this way, the generation of extra high-order irregular magnetic fields is prevented. Also, the superconducting coil 43 arranged in the area inside the circle or ellipse in which the coil cross sections of the coils 41, 41 'and 42, 42' are arranged corrects higher-order magnetic fields. . With such an arrangement, it is possible to generate a uniform magnetic field efficiently.

(Example 5)

This embodiment focuses on the properties of the magnetic field, and shows a coil arrangement for efficiently obtaining a uniform magnetic field. FIG. 7 is a schematic cross-sectional view showing the arrangement of the cross section of the superconducting coil as viewed on a cross section passing through the central axis of the split magnet in this embodiment.The superconducting coils 44 to 52 and 44 'to 52' The coils are arranged substantially concentrically with respect to the central axis, and the left and right coil groups are wound with respect to a substantially common central axis, and are arranged substantially mirror-symmetrically with a gap interposed between the central planes. ing.

The coil close to the central axis of the left and right superconducting coil groups is composed of a plurality of superconducting coils 48 to 52 arranged so that the windings overlap in the central axis direction. , 50 ′ are reverse current coils, which are arranged in the order of 2 or 1 <2.

This cancels out the second-order irregular magnetic field created by other superconducting coils, or the second and fourth-order irregular magnetic fields created by other superconducting coils. At least one of the superconducting coils 47, 48, 51, and 52 is located in one area, and cancels the fourth-order irregular magnetic field created by the other superconducting coils. As a result, the irregular magnetic field of the entire magnet can be effectively canceled, and a uniform magnetic field is formed at the coil center position on the order of 1 ppb.

Also, when the cross section of the coil is viewed along a cross section passing through the center axis of the coil, the cross section of the superconducting jir 49, 49 ', 50, 50' is arranged so as to overlap a common circular or elliptical arc. I have. And the superconducting coil 46, outside the circle or ellipse 46 ', 47, 47', 48, 48 'sectional force The superconducting coils 51, 51', 52, 52 'are arranged so as to overlap with the arc of a circle or ellipse. It is arranged to overlap the arc of the ellipse.

In this way, the superconducting coils whose coil cross sections are arranged in a circle or an ellipse on a cross section passing through the central axis are alternately arranged in the radial direction of the circle or the ellipse so that the directions of the flowing currents are opposite to each other. By arranging them, it is possible to efficiently cancel even higher-order magnetic fields, and a uniform magnetic field can be generated. A strong magnetic field of 10T or more with a uniformity of the order of 1 ppb required for nuclear magnetic resonance measurement, with a diameter of 1 err! Such an arrangement is suitable for efficient generation in a space of about 2 cm due to the nature of the magnetic field.

(Example 6)

In the present embodiment, a coil arrangement for obtaining a uniform magnetic field efficiently and with a very small number of coils is shown to facilitate the manufacture of the magnet. FIG. 8 is a schematic cross-sectional view showing the arrangement of the cross-section of the superconducting coil as viewed on a cross-section passing through the central axis in the present embodiment.

The superconducting coils 53 to 59 and 53 'to 59' are arranged almost concentrically with respect to the center axis in the horizontal direction, and the left and right coil groups are wound around a substantially common center axis. On the other hand, they are arranged almost mirror-symmetrically with a gap in between.

The superconducting coils 57, 58 of the left and right superconducting coil groups are arranged such that the windings overlap along the central axis. The superconducting coils 58 and 59 are reverse current coils, which are respectively arranged in the second and / or first two, and the second irregular magnetic field generated by the other superconducting coils or other superconducting coils. It cancels out the second and fourth order magnetic fields created by the coil.

In addition, at least one of the superconducting coils 56 and 57 is arranged in a vibrating << 1 to cancel the fourth-order irregular magnetic field created by the other superconducting coils. This (4) The irregular magnetic field of the entire magnet can be effectively canceled, and a uniform magnetic field of the order of 1 ppb is formed at the center of the coil.

Also, when the cross section of the coil is viewed along a cross-section passing through the center axis of the coil, the cross sections of the superconducting coils 58, 58 'and 59, 59' are arranged so as to overlap a common circular or elliptical arc. Puru. In addition, the cross section of the superconducting coil 55, 55 ', 56, 56', 57, 57 'on the ffl is arranged so as to overlap the arc of a certain circle or ellipse. As a result, the irregular magnetic field of the entire magnet is efficiently canceled with a smaller number of coils.

The reverse current coils 58 and 59 are located closer to the magnetic field generation position than the other superconducting coils. Thus, the magnitude of the magnetic field in the direction opposite to the central magnetic field created by the reverse current coil can be reduced, and the size of the entire magnet can be reduced.

With such an arrangement, even with a small number of coils, a uniform magnetic field can be formed at the coil center position on the order of 1 ppb, and the size of the magnet can be further reduced.

(Example 7)

In the present embodiment, the coil arrangement is shown in order to obtain a uniform magnetic field efficiently and with the smallest number of coils in order to obtain the most feasible and easy to manufacture magnets. FIG. 9 is a schematic cross-sectional view showing the arrangement of the cross-section of the superconducting coil as viewed on a cross-section passing through the central axis in the present embodiment.

The superconducting coils 60-66 and 60'-66 'are arranged almost concentrically with respect to the horizontal center axis, and the left and right coil groups are wound around a substantially common center axis. On the other hand, the superconducting coils 64 and 65 of the left and right superconducting coil groups, which are arranged almost mirror-symmetrically with a gap therebetween, are arranged so that the winding portions overlap each other along the central axis. Superconducting coils 65 and 66 are reverse current coils Are located at or <2 or 1 and <2, respectively, and the second-order irregular magnetic field created by another superconducting coil, or the second-order irregular magnetic field created by another superconducting coil and the fourth-order It cancels out the irregular magnetic field.

In addition, at least one of the superconducting coils 63 and 64 is arranged at <1, thereby canceling the fourth-order irregular magnetic field created by the other superconducting coils. Also, on a cross section passing through the center axis of the coil, the cross sections of the superconducting coils 65, 65 'and 66, 66' are arranged so as to overlap a common circular or elliptical arc.

In this way, by maintaining a certain distance from the uniform magnetic field space, the generation of extra high-order irregular magnetic fields is prevented. The cross section of the superconducting coils 62, 62 ', 63, 63', 64, 64 'is arranged outside thereof so as to overlap a certain circle or ellipse arc.

As a result, the irregular magnetic field of the entire magnet can be efficiently canceled with a smaller number of coils, and a uniform magnetic field is formed at the coil center position on the order of 1 ppb.

The reverse current coils 65 and 66 are located closer to the magnetic field generation position than the other superconducting coils. As a result, the magnitude of the central magnetic field generated by the reverse current coil and the magnitude of the magnetic field in the opposite direction can be reduced, and the size of the entire magnet can be reduced.

Also, the superconducting coil 60, which is far from the center axis of the coil, creates a magnetic field in the same direction as the main magnetic field, and is arranged at 2 or α or 3 so that the secondary It cancels out the irregular magnetic field of, or the secondary and tertiary magnetic fields created by other superconducting coils.

By arranging the superconducting coil 60 in this manner, the coil has the same function as a coil that is energized in the negative direction near the position where the magnetic field is generated, so that the amount of current in the negative direction can be reduced. Therefore, the magnetic field in the opposite direction to the central magnetic field generated by the negative current can be reduced, and the size of the magnet is reduced. be able to.

(Example 8)

It is desirable that the NMR apparatus has a small leakage magnetic field. Therefore, an embodiment of the present invention including the method of shielding the leakage magnetic field will be described below. FIG. 10 is a schematic cross-sectional view showing an arrangement of a cross section of the superconducting coil as viewed on a cross section passing through the central axis in the present embodiment.

The superconducting coils 160 to 166 generate a uniform magnetic field at the center of the magnet. In the present embodiment, the superconducting coils 165 and 166 are << reverse current coils, and generate a uniform magnetic field of the order of I ppb over the entire magnet. The superconducting coils 1 67 and 16 7 ′ are active shield coils, which minimize the leakage of the magnetic field to the outside.

(Example 9)

FIG. 11 is a schematic cross-sectional view showing the arrangement of the cross-section of the superconducting coil and the ferromagnetic material for the leakage magnetic field shield as viewed on a cross-section passing through the central axis in the present embodiment. The superconducting coils 173 to 179 generate a uniform magnetic field at the center of the magnet. In this embodiment, the superconducting coils 178 and 179 are << reverse current coils.

The cylindrical ferromagnetic material 171 and the disk-shaped ferromagnetic material 172 form a magnetic path, and suppress the leakage of the magnetic field generated by the superconducting coil group to the outside.

(Example 10)

FIG. 12 is a schematic cross-sectional view showing the arrangement of the cross-sections of the superconducting coil as viewed on a cross-section passing through the central axis and a ferromagnetic material for a leakage magnetic field shield in the present embodiment. The superconducting coils 184-188 generate a uniform magnetic field at the center of the magnet. The superconducting coil 188 closest to the uniform magnetic field space is a reverse current coil. The smaller the number of reverse current coils, the less the cancellation of the central magnetic field, and the smaller the size of the magnet as a whole. The superconducting coils 186 and 187 are split for adjusting the magnetic field. The superconducting coils 183, 182 prevent the magnetic field from leaking outward in the radial direction, and the disc-shaped ferromagnetic material 181 suppresses the magnetic field from leaking in the axial direction. (Example 11)

FIG. 13 is a schematic cross-sectional view showing a superconducting coil cross-sectional arrangement viewed on a cross-section passing through a central axis and a ferromagnetic material for a leakage magnetic field shield in the present embodiment. The superconducting magnets 194 to 200 generate a uniform magnetic field at the center of the magnet. Superconducting coil 1 99 and 200 force << reverse current coil. 196 and 197 are split for magnetic field adjustment.

The superconducting coils 192 and 193 prevent the magnetic field from leaking in the axial direction, and the cylindrical ferromagnetic material 191 suppresses the magnetic field from leaking in the radial direction.

The present invention has been described based on the embodiments. In each of the above-described embodiments, the coils inside the magnet are all superconducting coils. The present invention is not limited to only superconducting coils, and may be, for example, coils using copper wires or the like. Any material may be used as long as it can carry current.

Further, a permanent magnet may be used as the magnetomotive force source of the static magnetic field generation source. A shim coil for correcting magnetic field disturbance due to manufacturing errors or installation errors may be provided. The left and right coil groups of the split magnet are arranged almost mirror-symmetrically. In order to obtain better uniformity, it is desirable to arrange them in mirror symmetry. According to the above embodiment of the present invention, a uniform magnetic field of the order of 1 ppb is generated in the measurement space of the NMR analyzer for solution analysis using a split magnet, and the solenoid is utilized in this region by utilizing the split gap of the magnet. You can import a type of probe coil. For example, even with an 800 MHz device, measurement with SN sensitivity equivalent to that of a conventional 1 GHz class NMR device can be performed.

Furthermore, since the central magnetic field strength is relatively low, it is possible to shield the leaked magnetic field, and the installability is greatly improved. Industrial applicability

The nuclear magnetic resonance apparatus of the present invention and the superconducting magnet used therein can generate a uniform magnetic field of 1 ppb or less in the measurement magnetic field space, and can perform measurement with a high S / N ratio.

Claims

The scope of the claims

1. A nuclear magnetic resonance analyzer comprising a split-type magnet, wherein at least one of the coils constituting the split-type magnet is a reverse current coil for generating a magnetic field in a direction opposite to that of another coil. .

2. The nuclear magnetic resonance analyzer according to claim 1, wherein the magnetic field uniformity is in the order of 1 ppb, preferably 1 to 2 ppb, where the order of 1 ppb is defined as a single digit.

3. A superconducting coil, a cryogenic container containing the superconducting coil and a refrigerant for cooling the same, a permanent current switch connected to the superconducting coil, and a sample to be measured surrounded by the superconducting coil. It has a space to be inserted, and a probe coil installed at the center of the magnetic field in the space and having the sample placed inside, and the superconducting coil is wound so that a certain axis becomes a common central axis. There is a first coil group composed of a plurality of coils, and a second coil group composed of a plurality of coils wound around the central axis as a common central axis. The second coil group is disposed so as to oppose with a certain space therebetween, and if a coil that is energized in a direction that generates a magnetic field in the opposite direction to the main magnetic field is defined as a reverse current coil, the first coil group And the coils that make up the second coil group Except a coil having a maximum winding radius, nuclear magnetic resonance apparatus, characterized in that at least one coil is a reverse current coil.

4. A first coil group composed of a plurality of coils wound around a certain axis as a common central axis, and a plurality of coils wound around the central axis as a common central axis A first coil group and a second coil group are disposed so as to face each other with a certain space therebetween, and a nuclear magnetic resonance having a measurement area formed in the space. When a coil that is energized in a direction that generates a magnetic field in a direction opposite to the main magnetic field and is defined as a reverse current coil is a device magnet, of the coils forming the first coil group and the second coil group, A magnet for a nuclear magnetic resonance apparatus, wherein at least one coil is a reverse current coil except for a coil having a maximum winding radius.

5. The nuclear magnetic resonance apparatus according to claim 4, comprising a coil group arranged in a central axis direction such that winding portions overlap each other when the first coil group or the second coil group is viewed from the central axis direction. For magnet.

6. The magnet for a nuclear magnetic resonance apparatus according to claim 5, wherein the coil group in which the winding portions are arranged so as to overlap with each other is arranged in a region near a central axis.

7. The magnet for a nuclear magnetic resonance apparatus according to claim 6, wherein at least one of the coils arranged in the central axis direction such that the winding portions overlap each other is formed of a reverse current coil.

8. When a group of coils arranged so that the windings overlap each other is defined as a layer, a layer containing the first reverse current coil is formed on the center axis side, and a second reverse current coil is formed outside the layer. Wherein the second reverse current coil is located at a position closer to the gap than the first reverse current coil.

9. When observing the coil cross section on the cross section passing through the central axis, define the measurement space where the uniform magnetic field is formed as the origin, and define the angle between the straight line connecting the center of the coil cross section and the origin and the central axis. 6. The magnet for a nuclear magnetic resonance apparatus according to claim 1, wherein the reverse current coil is disposed at a position where the cross section of the reverse current coil is approximately 63.43 °.

10 0. When the coil section is viewed on a section passing through the center axis, at least one of the reverse current coils among the coils located close to the center axis is positioned at a position where the angle is 40.09 °. The magnet for a nuclear magnetic resonance device according to any one of claims 4 to 9, wherein:

1 1. When the coil cross section is viewed on a cross section passing through the center axis, the cross section of the reverse current coil is arranged so as to overlap a common circular or elliptical arc. A magnet for a nuclear magnetic resonance apparatus according to claim 4.

1 2. When the cross section of the coil is viewed on a cross section passing through the central axis, all cross sections of the reverse current coil are positioned inside and outside or outside the circle or ellipse where the main magnetic field is located. 12. The magnet for a nuclear magnetic resonance apparatus according to claim 11, wherein the cross sections of the coils generating the magnetic field in the same direction are arranged so as to overlap a common circular or elliptical arc.

1 3. The nuclear magnetic resonance according to any one of claims 4 to 9, wherein the reverse current coil is arranged at a position closer to a magnetic field generation position than a coil that generates a magnetic field in the same direction as other main magnetic fields. Magnet for equipment.

1 4. Any one of claims 4 to 9, wherein at least one of the coils that generate a magnetic field in the same direction as the main magnetic field in a coil far from the central axis is located at a position of> 73.43 ° A magnet for a nuclear magnetic resonance apparatus according to the above item.

1 5. The magnet for a nuclear magnetic resonance apparatus according to any one of claims 4 to 9, wherein the first and second multilayer coil groups are arranged mirror-symmetrically on opposing surfaces.

10. The magnet for a nuclear magnetic resonance apparatus according to any one of claims 4 to 9, further comprising a shield coil for shielding a leakage magnetic field and a ferromagnetic material for shielding a leakage magnetic field.

17. The magnet for a nuclear magnetic resonance apparatus according to claim 16, wherein a cylindrical ferromagnetic material and a shield coil are used.

18. The magnet for a nuclear magnetic resonance apparatus according to claim 17, wherein a disc-shaped ferromagnetic material and a shield coil are used.

1 9. The nuclear magnetic resonance apparatus according to any one of claims 4 to 9, wherein a steam coil for correcting disturbance of a uniform magnetic field due to a manufacturing error or an installation error is provided inside or inside and outside. magnet.

20. The coil according to claim 4, wherein the coil is made of a material having superconducting properties, and the coil has cooling means for cooling the coil to a temperature lower than the temperature at which the coil exhibits superconducting properties. The magnet for a nuclear magnetic resonance apparatus according to any one of the above.