JPH09127224A - Magic Angle PFG probe - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide a magic angle P in a nuclear magnetic resonance apparatus.
Obtain a probe with a simple configuration for FG measurement. SOLUTION: The magnetic field strength in the static magnetic field direction generated by the magnetic field generation coil in the static magnetic field direction and the magnetic field strength in the direction orthogonal to the static magnetic field generated by the magnetic field generation coil in the direction perpendicular to the static magnetic field are represented by vectors. In this case, a magic angle PFG probe in which a static magnetic field direction coil and a static magnetic field orthogonal direction coil are conductively connected in series so that a combined vector of the two vectors forms a magic angle direction when the same current is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear magnetic resonance apparatus, and more particularly to an apparatus for applying a magnetic field in a magic angle direction to a sample in a static magnetic field, and more particularly to a magic angle PFG (Pulsed Field).
d Gradient) to a sample.

[0002]

2. Description of the Related Art In a nuclear magnetic resonance apparatus, a PFG (P
A known method is to use pulsed gradients (ie, pulsed gradients of magnetic field strength in the static magnetic field direction) to reliably separate signals in close proximity to the sample and remove unwanted signals.

In order to carry out PFG measurement, a PFG coil is provided in a magnet that forms a highly stable static magnetic field.
The strength of a static magnetic field applied to a sample is changed. FIG. 1 is a diagram for explaining the PFG measurement, in which the static magnetic field + Δ and the static magnetic field −Δ are represented by the change in the magnetic field strength by the density.
The gradient of the magnetic field strength in the range is given in a pulse form.

In the NMR apparatus, a static magnetic field is widely formed by using a coil wound in a solenoid type such as a superconducting magnet. In order to enhance the measuring ability of the apparatus,
In order to obtain a higher static magnetic field, the diameter of the solenoid is reduced to increase the strength of the magnetic field.

On the other hand, in a nuclear magnetic resonance apparatus for measuring a solid sample, there is known a method of eliminating the mutual influence between a plurality of nuclei by inclining the solid sample with the magnetic field direction at an angle of 54 ° 44 '. And such an angle is called a magic angle.

It is known that the signal of light water in a liquid sample can be eliminated by the magic angle PFG measurement in which the PFG is tilted by the magic angle developed for measuring a solid sample and is given to the sample.

In order to perform the magic angle PFG measurement, it is necessary to tilt the PFG coil in the direction of the magic angle in a static magnetic field. However, when the diameter of the static magnetic field generating solenoid becomes smaller, there is no space in the solenoid for tilting the PFG generating coil in the magic angle direction. Therefore,
In order to apply the PFG in the magic angle direction in a limited space, a PFG coil is provided as shown in FIG.
The normal static magnetic field direction PFG coil 1 and the static magnetic field orthogonal direction coil 2 of FIG. 2B are wound on a cylindrical bobbin, one of which generates PFG in the static magnetic field direction 3 and the other of which generates a static magnetic field. Magic angle PFG measurement is realized by generating PFG in the orthogonal direction 4. As shown in FIG. 3 as a vector of intensity in the magnetic field direction, the magic angle PFG from the magnetic field by the PFG in the static magnetic field direction and the direction perpendicular to the static magnetic field
The magnetic field strengths formed by both coils are adjusted so that The magnetic field of the coil is adjusted by connecting the static magnetic field direction PFG power supply 5 to the static magnetic field direction PFG power supply 5 and connecting the static magnetic field direction PFG power supply 5 to the static magnetic field orthogonal direction as described in FIG. A PFG power supply 6 for the static magnetic field orthogonal direction is connected to the PFG coil 2, and the current supplied from both power supplies to both coils is adjusted to generate a PFG in the magic angle direction.

As described above, in the case where the measurement is performed by the magic angle PFG, the conventional apparatus shown in FIG.
Like the conductive connection relation of the coil of the power supply shown in Fig. 2, two power supplies for supplying current to the two coils in the static magnetic field direction and in the direction orthogonal to the static magnetic field are required. Therefore, the circuit for controlling the power supply is also required. Two pieces are required, and a control program for generating the PFG is also required for both coils, so that the measurement of the magic angle PFG has a problem that the device configuration and the measurement method are complicated.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a device having a simple structure capable of measuring a magic angle PFG with a single power supply device.

[0010]

The present invention provides a magic angle PFG probe for nuclear magnetic resonance measurement,
When the magnetic field strength in the static magnetic field direction generated by the magnetic field generation coil in the static magnetic field direction and the magnetic field strength in the direction orthogonal to the static magnetic field generated by the magnetic field generation coil in the direction orthogonal to the static magnetic field are expressed as vectors, respectively, Is a magic-angle PFG probe having a static magnetic field direction coil and a static magnetic field orthogonal direction coil that form a magic angle direction when the same current is applied.

Further, the above-mentioned magic angle PFG probe in which a static magnetic field direction coil and a static magnetic field orthogonal direction coil are conductively connected in series.

[0012]

Embodiments of the present invention will be described below.

Since the strength of the magnetic field generated by the coil is proportional to the electric current that flows, when the magnetic field strength of the magnetic field generating coil in the direction of the static magnetic field and the magnetic field strength in the direction orthogonal to the static magnetic field are represented by vectors, It was found that the combined vector of the two obtained when the same current is applied to the coil always holds a constant direction regardless of the magnitude of the current, and the same current is applied to the coil in the static magnetic field direction and the coil in the static magnetic field orthogonal direction. When a current is applied to the probe, a coil whose combined vector of the magnetic fields of the two forms a magnetic field in the magic angle direction is attached to the probe, the two are conductively connected in series, and the current is supplied from a single power source.

FIG. 5 shows the magic angle PFG of the present invention.
It is a figure explaining the connection relation of a coil and a power supply. Each coil is a coil that is set in advance so that the combined vector of the magnetic field strength in the static magnetic field direction and the magnetic field strength in the static magnetic field orthogonal direction obtained when the same current is applied is in the magic angle direction. The coils are connected in series. Therefore, since the same current is always applied to both coils, the magnetic field synthesized by both coils is always a magnetic field in the magic angle direction regardless of the magnitude of the applied current, and the magic angle PFG measurement is simply performed by changing the applied current. , Magic angle direction PFG
Can be realized.

The coil used in the magic angle PFG of the present invention has the same coil diameter and number of turns as the ordinary coil design, depending on the required magnetic field strengths in the static magnetic field direction and in the direction perpendicular to the static magnetic field. It can be designed and manufactured by defining the above.

[0016]

[Effects of the Invention] A coil in which the combined vector of the magnetic field strength of the static magnetic field direction magnetic field generating coil and the vector representing the static magnetic field orthogonal direction magnetic field strength when the same current is applied is in the magic angle direction is prepared and attached to the probe. Since the conductive connection is made in series, the PFG measuring device can be obtained with only a single power supply device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating PFG measurement.

FIG. 2 is a diagram illustrating a coil that provides a PFG in a magic angle direction.

FIG. 3 is a diagram illustrating a relationship between a vector of magnetic field strength in a static magnetic field direction and a vector of magnetic field strength in a direction orthogonal to the static magnetic field and a magic angle.

FIG. 4 is a diagram illustrating a connection relationship between a power supply and a coil for measuring a conventional magic angle PFG.

FIG. 5 is a diagram illustrating a connection relationship between a magic angle PFG coil and a power source according to the present invention.

[Explanation of symbols]

1 ... PFG coil for static magnetic field direction, 2 ... Coil for static magnetic field orthogonal direction, 3 ... Static magnetic field direction, 4 ... Static magnetic field orthogonal direction, 5 ... Static magnetic field direction PFG, 6 ... Static magnetic field orthogonal direction PFG power supply,
7 ... PFG power supply

Claims (2)

[Claims] 1. In a magic angle PFG probe for nuclear magnetic resonance measurement, a magnetic field strength in a static magnetic field direction generated by a magnetic field generation coil in a static magnetic field direction and a static magnetic field generated in a magnetic field generation coil in a direction orthogonal to the static magnetic field are measured. When the magnetic field strength in the orthogonal direction is expressed by a vector, the combined vector of the two vectors forms a static magnetic field direction coil and a static magnetic field orthogonal direction coil that form a magic angle direction when the same current is applied. A magic angle PFG probe having. 2. A static magnetic field direction coil and a static magnetic field orthogonal direction coil are electrically conductively connected in series.
The Magic Angle PFG probe described.