JPH088917B2 - High frequency probe for NMR - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a high-frequency probe for NMR (nuclear magnetic resonance),
In particular, the present invention relates to a high-frequency probe for NMR that does not cause magnetic interference with a low-frequency pulsed magnetic field used at the same time.

[Conventional technology]

FIG. 3 shows, for example, “Journal of Magnetic Resonanc”.
e) ”, Vol. 36, pp. 447 to 451 (1979), which is a perspective view showing a conventional high-frequency probe for NMR. In the figure, (1) is a coil in which a pair of H-shaped conductor plates, for example, copper plates are arranged so as to form a hollow cylindrical body, and a non-protruding portion (1a) called a vertical band (vertical band). ) And a wing (1b). (2) is a fixed capacitor that is inserted between the adjacent protrusions (1b) and soldered to the protrusions (1b). (3) is a pair of conductor rings for electric field shielding that are arranged inside the protrusion (1b) via an insulating layer (not shown), and one conductor ring (3a) is a tob guard ring. And the other conductor ring (3b) is called the bottom guard ring.

The conventional high frequency probe for NMR is configured as described above, and the coil (1), the fixed capacitor (2), and the conductor ring (3) form a three-dimensional circuit equivalently acting as an LC series resonance circuit. The conductor ring (3) is used for the electric field shield as described above, that is, for reducing the dielectric loss in the measurement target due to the generated electric field when the measurement target is installed in the high frequency probe for NMR. In fact, when an NMR image is obtained using this high-frequency probe for NMR, a known gradient magnetic field pulse is simultaneously applied to the sample.

[Problems to be solved by the invention]

In the conventional high-frequency probe for NMR, an eddy current flows through the non-protruding portion (1a) with the application of the gradient magnetic field pulse, which causes a problem that waveform distortion or phase distortion occurs in the gradient magnetic field pulse.

The present invention has been made to solve such a problem, and an object thereof is to obtain a high-frequency probe for NMR that does not cause waveform distortion or phase distortion in a gradient magnetic field pulse.

[Means for solving problems]

In the high frequency probe for NMR according to the present invention, the non-protruding portion in the conventional device is composed of a plurality of conductive segments, and a capacitor is inserted in at least a part of the conductive segments.

[Action]

In the present invention, the capacitor inserted in the conductive segment turns on or off the eddy current.

〔Example〕

FIG. 1 is a perspective view showing an embodiment of the present invention,
(2) and (3) are exactly the same as in the conventional device. (11) is a coil arranged so as to form a hollow cylindrical body such as a cylinder or an elliptic cylinder, and the coil (11) includes two pairs of conductor plates such as copper plates (11a) and (11b).
And the upper and lower conductor plates (11a and 11b) are connected to each other to form a plurality of H-shaped conductive segments (11c). Each conductive segment (11c) is, for example, a thin conductor plate, conductor wire or conductor pipe. The upper conductor plates (11a) are bent and then joined by a fixed capacitor (2). Similarly, the lower conductor plates (11b) are also bent and then fixed capacitor (2). They are joined together to form the hollow cylindrical body described above. Furthermore, capacitors (12) are individually inserted in the conductive segments (11c), and the capacitance C of these capacitors (12) is set to, for example, about 0.1 μF to 0.01 μF. As a result, the impedance of this capacitor (12) is 1600Ω at 1KHz.
It is ~ 16000Ω and 0.03Ω ~ 0.3Ω at 60MHz.

Further, the frequency of the gradient magnetic field pulse is about 1 KHz, and the frequency of the NMR signal is, for example, about 60 MHz. Therefore, the capacitor (1
The presence of 2) does not affect the operation of the high-frequency probe of 60 MHz, for example, because the impedance is small.

However, the resistance of the eddy current due to the gradient magnetic field is 1 KΩ or more, so the eddy current can be turned off or turned off.

In FIG. 2, the path of the eddy current when there is no capacitor (12) is shown by an arrow.

In the above embodiment, all the conductive segments (11
The capacitor (12) was inserted in c), but the capacitor (1
There may be a conductive segment (11c) in which 2) is not inserted.

Further, in the above embodiment, the hollow cylindrical body is a cylinder, but it may be an elliptic cylinder.

Further, although two pairs of conductor plates (11a) and (11b) are used, four or more pairs of conductor plates can be used by dividing each conductor plate into two or more.

In addition to the copper pipe, the conductive segment may be a copper plate having a narrow copper wire width.

〔The invention's effect〕

As described above, according to the present invention, the non-protruding portion in the conventional device is composed of a plurality of conductive segments, and the capacitor is inserted in at least a part of the conductive segments.
There is an effect that a high-frequency probe for NMR that does not cause waveform distortion or phase distortion in the gradient magnetic field pulse can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a view showing an eddy current path, and FIG. 3 is a perspective view showing a conventional high frequency probe for NMR. In the figure, (11) is a coil, (11a) and (11b) are conductor plates, (11c) is a conductive segment, (2) is a fixed capacitor, (3) is a conductor ring, and (12) is a capacitor. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (6)

[Claims] 1. A coil arranged to form a hollow cylindrical body by two or more pairs of conductor plates and a plurality of conductive segments connecting upper and lower conductor plates, and conductor plates on the same plane. For NMR, characterized in that it comprises a fixed capacitor for connecting, a conductor ring concentrically installed inside the conductor plate on the same plane, and a capacitor inserted in at least a part of the conductive segment. High frequency probe. 2. The high frequency probe for NMR as set forth in claim 1, wherein the hollow cylindrical body is a cylinder. 3. The high-frequency probe for NMR as set forth in claim 1, wherein the hollow cylindrical body is an elliptic cylinder. 4. The high frequency probe for NMR as set forth in claim 1, wherein the conductive segment is a thin conductor plate. 5. The high frequency probe for NMR as set forth in claim 1, wherein the conductive segment is a conductive wire. 6. A high-frequency probe for NMR use according to claim 1, wherein the conductive segment is a conductor pipe.