JPH0318450B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sample coil used in a probe of a nuclear magnetic resonance (NMR) device, and particularly relates to a coil structure that can detect NMR signals with high sensitivity up to high frequencies. be.

[Prior art] In an NMR device, a probe containing a sample is placed in a uniform static magnetic field, and a high-frequency magnetic field for excitation is irradiated from a sample coil placed in the probe close to the sample. The resonance signal from the sample coil is received by the sample coil, sent to the computer via the receiving circuit, and processed by Fourier transformation.
Obtaining NMR spectra. At this time, great attention is paid to the shape and structure of the coil, as the quality of the coupling between the coil and the resonator of the sample greatly affects the sensitivity of the NMR device. Using superconducting magnets
In the case of an NMR apparatus, a cylindrical saddle-shaped coil as shown in FIG. 4, for example, has been commonly used. In the saddle-shaped coil shown in Fig. 4, two spirally wound coil parts 1 and 2 are arranged symmetrically around the cylindrical axis Z around a cylindrical region of radius R in which a sample tube containing a sample is arranged. has been done. This spiral winding coil part is
Linear parts 1A, 2A parallel to the cylinder axis Z, and arcuate parts 1B, 2B in a plane perpendicular to the cylinder axis Z.
It consists of. FIG. 5 shows a cross-sectional view of the linear portion A taken along a plane perpendicular to the cylindrical axis Z,
Linear parts 1A and 2A are arranged symmetrically on the circumference of a radius R with the Y plane in between, and by this coil
A high frequency magnetic field is generated in the direction.

[Problems to be solved by the invention] The common idea of the conventional coils as described above is that
This means that two spirally wound coil parts 1 and 2 with the same shape are arranged facing each other from both sides with a cylindrical area in between, and therefore the number of turns of the coil is an even number of turns such as 2, 4, 8, etc. become.

By the way, in recent years it has become possible to obtain strong static magnetic fields using superconducting magnets, and along with this, the observation frequency is also being raised from about 400MHz to 500MHz or 600MHz. In order to increase the observation frequency in this way, the sample coil must have a small inductance, a high tuning frequency, and a Q
High quality is required.

In such cases, conventionally, a two-turn coil as shown in FIG. 5 has been used because it has the least number of turns and can minimize inductance. However, even if such a coil is used, the inductance cannot be made sufficiently small, and conventionally, this coil has been used even though it is known that it is undesirable.

The present invention has been made in view of this point, and provides a one-turn coil by arranging the winding wire on the Y plane, which would never be arranged based on the conventional concept described above, and thereby reducing the inductance. The purpose is to provide a small coil and a coil with extremely high sensitivity.

[Means for solving the problem] In order to achieve this objective, the present invention
The NMR probe coil is a coil that is wound around a cylindrical sample area and generates a high-frequency magnetic field in a direction perpendicular to the axis of the cylinder, and extends in a direction parallel to the cylinder axis. a pair of linear conductive pieces arranged approximately symmetrically with each other;
a first arcuate conductive piece for connecting the ends of a pair of linear conductive pieces to form a coil; and a first arcuate conductive piece that is substantially symmetrical with respect to the center of the sample area. a second arc-shaped electrically conductive piece arranged to have a conductive property, the second arc-shaped electrically conductive piece is composed of a plurality of arc-shaped electrically conductive pieces, and the plurality of arc-shaped electrically conductive pieces are
a second arc-shaped conductive piece connected to the other end of the straight conductive piece so as not to connect the pair of straight conductive pieces; a pair of leads connected to said pair of linear conductive pieces or a second arcuate conductive piece for flowing through one arcuate conductive piece to the other linear conductive piece; It is characterized by having the following.

It is characterized by

[Example] Hereinafter, an example of the present invention will be described in detail using the drawings.

FIG. 1 shows an example of a coil embodying the present invention, in which a shows the shape when it is punched out from a conductor plate, and b shows the state when it is formed into a cylindrical shape. In FIGS. 1a and 1b, the coil consists of linear conductors L1, L2 parallel to the cylindrical axis Z, and linear conductors L1, L2 parallel to the cylindrical axis Z.
Arc-shaped conductors L3 and L4 for connecting L2 in series to form a coil, second arc-shaped conductors L5 to L8 for compensation, and leads L9 and L10 for connecting the coil to an external circuit. It consists of

When the arc-shaped conductor L4 is punched out from the conductor plate, it is divided into two parts, and when formed into a cylindrical shape as shown in Fig. 1b, they are slightly overlapped, and the overlapping parts are connected by, for example, soldering. It has been unified.

Further, the second arc-shaped conductors L5 to L8 do not have the role of a coil, as can be seen from the fact that they are not connected to each other, and the second arc-shaped conductors L5 to L8 do not have the role of a coil, and are located at the first arc-shaped conductor L5 to L8, with the center origin O of the cylindrical region where the sample is placed. This is provided for the purpose of compensating for disturbances in the uniformity of the static magnetic field by arranging a conductor of substantially the same shape at a position symmetrical to the arc-shaped conductor. Therefore, the widths of the first and second arc-shaped conductors are set to be equal to each other.

Figure 2 shows the coil in Figure 1 at the center of the cylindrical area O.
A sectional view taken along an XY plane perpendicular to the cylinder axis Z is shown in FIG. As can be seen from this figure, the linear conductors L1 and L2 are arranged on an axis (Y-axis) perpendicular to the axis of the high-frequency magnetic field (X-axis), and a one-turn coil is realized. Therefore, according to the present invention, the conventional two
1 with smaller inductance than a turn coil
A coil of turns is realized.

Moreover, the high-frequency magnetic field strength that a straight conductor placed at this position (on the Y plane) generates in the X-axis direction at the center origin O of the cylindrical area placed on the sample is different from that at any other position of the straight conductor. Since it is stronger than when it is placed, it has a high Q as a coil. Therefore, according to the present invention, it is possible to irradiate a sample with a strong high-frequency magnetic field using a highly efficient coil with a high Q, and to efficiently detect a strong resonance signal derived from the strong high-frequency magnetic field irradiation. This synergistic effect significantly increases the sensitivity of the NMR device.

In the above embodiment, the linear conductors L1 and L2 are
Connected in parallel with two arc-shaped conductors L3 and L4,
Since only one connection is required, it is not necessarily necessary to electrically connect the two halves of the arc-shaped conductor L4, and they may be left separated with a slight interval between them. However, it is not preferable to completely eliminate the arc-shaped conductor L4 because the presence of the conductor becomes asymmetrical.

FIG. 3 shows an example in which this point is taken into consideration and the lead extraction position is moved closer. Figure a shows the state in which it has been punched out from the conductor plate, and figure b shows the state in which it has been formed into a cylindrical shape.

The coil of the present invention can be formed by pasting a conductor wire onto a bobbin, by forming it by vapor deposition technology on the surface of the bobbin, in addition to being punched out from the conductor plate as described above, or by forming a printed circuit on a substrate with or without flexibility. It can be manufactured by forming it as. If the conductor has sufficient strength, it is not necessary to support it with another support such as a bobbin, and the conductor can stand alone.

In the above embodiment, the linear conductors are arranged exactly symmetrically with respect to the Z axis, but the linear conductors only need to be arranged substantially symmetrically, and a slight deviation is allowed.

[Effects of the Invention] As described in detail above, according to the present invention, an NMR probe coil with small inductance can be realized with one turn, so that it can sufficiently cope with an increase in observation frequency. Moreover, since the coil of the present invention has a high Q, it is possible to improve the sensitivity of the NMR apparatus.

[Brief explanation of drawings]

1 and 3 are diagrams each showing an example of a coil embodying the present invention, FIG. 2 is a diagram for explaining the arrangement of linear conductors around the Z axis in the coil of FIG. 1, and FIG. 5 and 5 are diagrams for explaining a conventional saddle-shaped coil. L1, L2: straight conductors, L3 to L10: arc conductors.

Claims (1)

[Scope of Claims] 1. A coil that is wound around a cylindrical sample region and that generates a high-frequency magnetic field in a direction perpendicular to the axis of the cylinder, and that extends in a direction parallel to the cylindrical axis. a pair of linear conductive pieces arranged substantially symmetrically across the pair of linear conductive pieces; and a first arc-shaped conductive piece for connecting the tips of the pair of linear conductive pieces to form a coil. a second arcuate conductive piece arranged so as to be substantially symmetrical with the first arcuate conductive piece with respect to the center of the sample region, the second arcuate conductive piece comprising a plurality of arcuate conductive pieces; a second arcuate conductive piece, the second arcuate conductive piece being connected to the other end of the linear conductive piece such that the plurality of arcuate conductive pieces do not connect the pair of linear conductive pieces; a conductive piece;
said pair of linear electrically conductive segments or a second arcuate electrically conductive segment to allow current to flow from one linear electrically conductive segment through the first arcuate electrically conductive segment to the other linear electrically conductive segment.
A coil for an NMR probe, comprising a pair of leads connected to the arc-shaped conductive piece. 2. The NMR probe coil according to claim 1, wherein the conductive piece is a conductive wire with a circular cross section. 3. The NMR probe coil according to claim 1, wherein the conductive piece is formed of a plate-shaped conductor. 4. The NMR probe coil according to any one of claims 1 to 3, wherein the coil is supported by a hollow cylindrical bobbin. 5. The NMR probe coil according to claim 4, wherein the coil is formed on the bobbin by vapor deposition. 6. The coil for an NMR probe according to claim 1, wherein the coil comprises a circuit and a circuit supported by an insulating substrate. 7. The NMR probe coil according to claim 6, wherein the insulating substrate has flexibility and is bendable. 8. The coil according to any one of claims 1 to 3, wherein the coil has strength to maintain itself.
Coil for NMR probe.