JPH04125407U - ESR device - Google Patents

Abstract

(57) [Summary] [Purpose] In a magnetic circuit in which a permanent magnet is sandwiched between a pair of yokes, the uniformity of the magnetic field strength within the air gap is good, and the magnetic field strength is continuously maintained while maintaining high uniformity. To provide an ESR device having a small and lightweight magnetic circuit, which can change the magnetic field strength in the Z-axis direction within an air gap with a high degree of uniformity, and which can be changed with high accuracy. [Structure] A magnetic pole piece 5 is attached to one end of a pair of plate yokes 1 and 2.
6 is fixed, and permanent magnets 3 and 4 are placed opposite each other at the other end.
A plate-shaped magnetic resistance adjustment member 7 is arranged between the permanent magnets 3 and 4 so that it can be inserted and removed in a direction perpendicular to the magnetic path, and the magnetic resistance of the magnetic path is continuously variable to continuously and continuously increase the magnetic field strength. Change in precision.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This idea uses a permanent magnet magnetic circuit as a magnetic field generator to receive and receive microwaves. Regarding an electron spin resonance device (hereinafter referred to as an ESR device) that combines a A magnetic circuit with a permanent magnet sandwiched between yokes continuously adjusts the magnetic field strength within the required air gap. Therefore, for example, a permanent magnet can be divided and a magnet that can be inserted and removed between the magnets in a direction perpendicular to the magnetic path. The magnetic resistance adjustment member is arranged to make the magnetic resistance continuously variable, and the magnetic circuit is assembled. ES that improves the symmetry of the magnetic field uniformity in the Z-axis direction of the air gap, which is extremely difficult to adjust after Regarding the R device.

0002

[Conventional technology]

ESR devices are widely used in the fields of research and development for chemical analysis. Also, E The SR device can detect unpaired electrons due to natural radiation damage to the measured object. Recently, archaeology, which can accurately measure the age of artifacts, geological minerals, and fossils, It is also used in the fields of science and earth science.

0003 The ESR device used for such purposes consists of a magnetic field generator and a microwave connected to it. Consisting of a receiving and transmitting device, it continuously transmits the highly accurate and uniform magnetic field generated during measurement. In order to measure the magnetic field strength that causes magnetic resonance by changing it, conventional magnetic field generators , the generation of a magnetic field within the required air gap and the continuous change in the magnetic field strength, and the current applied to the electromagnet. An electromagnetic magnetic circuit was used, which could be easily implemented by continuously varying it.

0004 Since the ESR device using an electromagnetic magnetic circuit is large, a small one using a permanent magnet is required. A lightweight ESR device was required, but the opposing distance (gap length) between a pair of permanent magnets In a configuration where the magnetic field strength is changed by changing the magnetic field strength, the uniformity of the magnetic field deteriorates. A configuration has been proposed that changes the magnetic field strength required for measurement with the required high precision uniformity. Therefore, ESR devices using permanent magnet magnetic circuits had not been put into practical use.

[0005] Therefore, the applicant has considered a configuration that continuously changes the magnetic field strength within the required air gap. Previously, we proposed an ESR device using a permanent magnet magnetic circuit. In other words, a permanent magnet is placed on each opposing surface of a pair of yokes that are placed opposite each other with a gap in between. Place the yoke on at least one of the pair of yokes, attach a magnetic pole piece to the surface facing the magnet, and A movable yoke is arranged to continuously change the distance between the opposing surfaces, and the permanent magnet The magnetic resistance of the magnetic path formed by the yoke and the movable yoke can be adjusted by operating the movable yoke. We proposed a configuration in which the magnetic field strength within the air gap can be continuously varied and continuously adjusted. -104574).

[0006]

[Problem that the idea aims to solve]

In a permanent magnet magnetic circuit, it is possible to continuously change the magnetic field strength while maintaining uniformity. Although it is difficult to The configuration uses a movable yoke to change the magnetic field strength while maintaining high uniformity. The degree can be changed.

[0007] However, in order to change the distance between the opposing surfaces of the yoke by moving the movable yoke, it is necessary to A relatively large force is required, and the movement of the movable yoke destroys the symmetry of the magnetic path, causing There were problems affecting the uniformity of the magnetic field strength within the gap. In particular, the uniformity of the magnetic field strength within the air gap must be uniform in the X, Y, and Z axes. Conventionally, the magnetic field strength was adjusted after assembling the magnetic circuit, but Adjustment in the direction, ie, the Z-axis direction, was extremely difficult. In addition, the above movable yoke is a magnetic circuit in which a permanent magnet is sandwiched between a pair of yokes. I can not use it.

[0008] This idea is based on a magnetic circuit in which a permanent magnet is sandwiched between a pair of yokes. Good uniformity of magnetic field strength, and continuous magnetic field strength while maintaining high uniformity The magnetic field strength can be changed with high precision, especially the uniformity of the magnetic field strength in the Z-axis direction within the air gap. The aim is to provide an ESR device with a compact and lightweight magnetic circuit that has a highly flexible configuration. are doing.

[0009]

[Means to solve the problem]

This idea is A permanent magnet is sandwiched between one end of a pair of yokes, and each magnetic pole is placed at the other end of the yoke through an air gap. It consists of a magnetic circuit with a permanent magnet, a yoke, and a magnetic pole piece attached to form a magnetic path. Insert/extract the magnet between the permanent magnets or into the hole provided in the permanent magnet in a direction perpendicular to the magnetic path. This is an ESR device characterized in that a magnetic resistance adjusting member is optionally arranged.

0010

[Effect]

The magnetic circuit based on this idea consists of dividing or perforating the permanent magnet sandwiched between the yokes. By arranging a magnetic resistance adjustment member that can be inserted and extracted in a direction perpendicular to the magnetic path, , formed by a permanent magnet, a yoke, and a magnetic pole piece by changing the insertion amount of the magnetic resistance adjustment member. The magnetic resistance of the magnetic path can be changed continuously, and the magnetic pole pieces can be placed in the air gap facing each other. A continuously changing magnetic field can be created.

[0011] In this invention, the magnetic resistance adjusting member is arranged between a pair of divided permanent magnets or The permanent magnet is penetrated or has a hole of the required depth in the direction perpendicular to the magnetic path, and the magnetic path is Any shape may be used as long as it is suitable for insertion and removal in orthogonal directions. The shape and dimensions may be determined depending on the required amount of change in the magnetic field within the air gap. For example, a pair of plate-shaped yokes with magnetic pole pieces attached to opposing surfaces and placed facing each other with a gap in between. When sandwiching a permanent magnet, place the magnetic resistance adjustment member on the center cross section between the opposing magnetic pole pieces. A simple structure in which a certain permanent magnet is divided and placed between them allows magnetic pole pieces to be aligned in opposite directions. A symmetrical magnetic path can be formed. In addition, the permanent magnet was divided into multiple parts and magnetic resistance adjustment members were placed according to the number of divisions. By drilling a through hole in the required part of the permanent magnet, it is possible to insert and insert a bar with a similar shape to the hole. or by creating a hole that does not pass through and inserting and extracting a rod-shaped magnetic resistance adjustment member. Various configurations can be adopted, such as arranging the By arranging one or more magnetic resistance adjustment members, the length, amount, and shape of the magnetic path can be adjusted. It is desirable to consider not to damage the symmetry of any magnetic path. The material for the magnetic resistance adjustment member is the same as the yoke, or a different material can be selected as appropriate. In addition, it is not necessary that the magnetic resistance adjustment member and the permanent magnet come into contact with each other, and the embodiment It is also possible to provide a gap suitable for insertion and removal, as shown in FIG. In addition, since the magnetic resistance adjustment member is configured to be inserted and removed in a direction perpendicular to the magnetic path, It has the advantage that less force is required to change the insertion amount.

0012 In this invention, the pair of yokes that sandwich the permanent magnet are shaped like the permanent magnet, such as a rectangular plate shape. It can be arbitrarily selected depending on the shape, magnetic properties, etc. Also, a magnetic pole piece is placed on the opposing surface. Magnetic pole piece, such as sandwiching a permanent magnet between a pair of plate-shaped yokes that are installed and placed opposite each other with a gap in between. Any shape may be used as long as it can form a magnetic path symmetrical in the opposing direction.

[0013] Permanent magnets that generate magnetic fields include rare earth magnets, ferrite magnets, etc. Select a known material and its shape depending on the magnetic field strength, the size of the device, etc. This is desirable. In particular, R is a resource-rich light rare earth mainly containing Nd and Pr. extremely high energy product of 30 MGOe or more with B and Fe as the main components. By using Fe-B-R permanent magnets that generate I can do that.

[0014] The magnetic pole pieces are effective in improving the magnetic field homogeneity within the air gap. as a magnetic pole piece Various known configurations can be adopted, but in particular, a trapezoidal or trapezoidal cross-section can be used at the periphery of the disc-shaped magnetic pole piece. A configuration in which an annular protrusion such as a rectangular or rectangular protrusion is provided is desirable.

[0015] Note that the ESR device applies a modulated magnetic field to the above-mentioned magnetic circuit within the air gap. A sweep magnetic field application that applies a sweep magnetic field to the applying coil and/or the air gap. an application coil and a cavity resonator placed in the gap into which the sample to be measured can be inserted. A configuration that includes a microwave oscillator and a microwave detector attached to the cavity resonator. Consisting of

[0016]

【Example】 Example 1 The magnetic circuit for the ESR device according to this invention shown in FIG. 1A consists of a pair of plate yokes 1 , 2, plate-shaped permanent magnets 3 and 4 are arranged on opposing surfaces of one end of the magnets 3 and 2, respectively, with different magnetic poles facing each other. Further, magnetic pole pieces 5 and 6 are fixed to the other end of each opposing surface and are opposed to each other.

[0017] Further, a plate-shaped magnetic resistance adjustment member 7 is provided between the pair of permanent magnets 3 and 4 that are arranged opposite to each other. In other words, the center crossing between the opposing magnetic pole pieces 5 and 6 on the surface, directly along the magnetic path formed by the permanent magnet, yoke, and magnetic pole piece (shown by the broken line in Figure 1). Platy magnetic resistance adjustment members 7 having a required thickness are slidably arranged in the intersecting directions, and the opposite A required air gap 8 is formed between the magnetic pole pieces 5 and 6.

[0018] BH (max) on permanent magnets 3 and 4 (166mm x 160mm x 29.5mm) Using a Fe-B-Nd magnet with 40 MGOe, the outer diameter of the magnetic pole pieces 5 and 6 was 52 mm. , the distance between the magnetic pole pieces 5 and 6 (air gap 8) was set to 22.4 mm, and the magnetic resistance adjustment section Using a plate with a thickness of 166 mm x 160 mm x 8 mm as the material 7, attach the permanent magnet 3, Insert and remove the magnetic resistance adjusting member 7 between the gaps 8 and 4 to examine the change in magnetic flux density at the center of the air gap 8. Ta. The results are shown in FIG.

[0019] In addition, the above condition with the magnetic resistance adjustment member 7 completely inserted between the permanent magnets 3 and 4 Changes in the magnetic flux density in the X, Y, and Z directions at the center of the air gap 8 of the magnetic circuit were investigated. The result Shown in Figure 3. In addition, the curve plotted with ○ in Figure 3 is in the X direction, and the curve plotted with △ The plotted curve shows the Y direction, and the curve plotted with an x mark shows the Z direction.

[0020] Insert and remove the magnetic resistance adjusting member 7 between a pair of permanent magnets 3 and 4 in a direction perpendicular to the magnetic path. By making this possible, the magnetic resistance of the magnetic path can be changed continuously, and the As shown in 2, the magnetic flux density within the air gap can be freely changed by inserting and removing the magnetic resistance adjustment member. As shown in Figure 3, the distribution of magnetic flux density within the air gap changes after assembly. It can be seen that the magnetic field is symmetrical in the Z-axis direction, where it is difficult to adjust the magnetic field. Furthermore, by adjusting the magnetic fields in the X-axis and Y-axis directions, the X, Y, A magnetic circuit that generates a magnetic field that is uniform and directionally symmetrical in both Z-axis directions can be obtained. It will be done.

[0021] Example 2 The magnetic circuit for another ESR device according to this invention shown in FIG. 1B is the same as that in Example 1. A permanent magnet 10 is arranged between one end of a pair of plate-shaped yokes 1 and 2, and Magnetic pole pieces 5 and 6 are fixed to the other end and are opposed to each other to form a gap. A hole is provided in the center of the permanent magnet 10 in the direction of the air gap, and a prismatic magnetic field is formed. A resistance adjustment section 11 is arranged so as to be insertable and removable in a direction perpendicular to the magnetic path.

[0022] BH (max) is 40M for permanent magnet 10 (60mm x 160mm x 40mm) Using GOe's Fe-B-Nd magnet, the outer diameter of the magnetic pole pieces is 52 mm, and the distance between the magnetic pole pieces is 52 mm. (air gap) is set to 22.4 mm, and the magnetic resistance adjustment member 11 is set to 60 mm x 39 mm. The magnetic resistance adjustment member 1 is placed inside the permanent magnet 10 using a bar material with a thickness of mm x 18 mm. 1 was inserted and extracted, and changes in magnetic flux density at the center of the gap were investigated. The results are shown in Figure 4. . In addition, the above-mentioned magnetic resistance adjustment member 11 is completely inserted into the permanent magnet. Changes in magnetic flux density in the X, Y, and Z directions at the center of the air gap in the circuit were investigated. The results are shown in Figure 5. show.

[0023] The magnetic resistance adjusting member 11 can be inserted into and removed from the permanent magnet 10 in a direction perpendicular to the magnetic path. By doing this, it is possible to continuously change the magnetic resistance of the magnetic path, as shown in Figure 4. The magnetic flux density within the air gap can be freely changed by inserting and removing the magnetic resistance adjusting member. As shown in Figure 5, the distribution of magnetic flux density within the air gap is Generates a magnetic field that is extremely uniform in all directions and has excellent directional symmetry. A dynamic magnetic circuit was obtained.

[0024]

[Effect of the idea]

The magnetic circuit based on this idea splits the permanent magnet sandwiched between the yoke or A magnetic resistance adjusting member that can be inserted and removed in a direction perpendicular to the magnetic path is placed in the hole provided in the Due to the simple configuration, the magnetic field strength within the air gap maintains good uniformity and high uniformity. At the same time, the magnetic resistance of the magnetic path is continuously variable, and the magnetic field strength can be adjusted continuously and with high precision. The air gap Z can be changed and is extremely difficult to adjust after assembling the magnetic circuit. By improving the symmetry of the magnetic field uniformity in the axial direction, it is possible to simplify the configuration and make it ultra-compact. It is ideal for ESR equipment.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a magnetic circuit for an ESR device according to the present invention, where A is a front longitudinal explanatory view and B is a side explanatory view showing the configuration of another magnetic circuit.

FIG. 2 is a graph showing the relationship between the insertion amount of the magnetic resistance adjusting member and the center magnetic flux density of the air gap.

FIG. 3 is a graph showing the relationship between distance from the center of the air gap and magnetic flux density.

FIG. 4 is a graph showing the relationship between the insertion amount of the magnetic resistance adjusting member and the center magnetic flux density of the air gap.

FIG. 5 is a graph showing the relationship between distance from the center of the air gap and magnetic flux density.

[Explanation of symbols]

1,2 Plate yoke 3,4,10 Permanent magnet 5,6 Magnetic pole piece 7,11 Magnetic resistance adjustment member 8 void

Claims (1)

[Scope of utility model registration request] Claim 1: A permanent magnet is sandwiched between one end of a pair of yokes,
It consists of a magnetic circuit in which a magnetic pole piece is attached to the other end of the yoke through a gap, and a magnetic path is formed between the permanent magnet, the yoke, and the magnetic pole piece, and a hole is formed between the divided permanent magnets or in the permanent magnet. An ESR device, characterized in that a magnetic resistance adjustment member is arranged in the section so as to be insertable and retractable in a direction perpendicular to a magnetic path.