JP2001110598A - Inserting light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce processing cost and assembling cost of a short cycle length inserting light source having cycle length less than 10 mm. SOLUTION: Gaps 6a are provided cyclically on the magnet block 1. Gaps 6b provided cyclically on the magnet block 9 having vertical magnetizing direction to the magnet block 1. These are assembled to obtain a compound magnet block 19. These magnet blocks are assembled to form a insert light source having cycle length of less than 10 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact insertion light source having a short period length and a large number of periods, which is inserted into a linear portion of an electron accelerator or an electron storage ring to generate high-luminance radiation.

[0002]

2. Description of the Related Art An insertion light source (see FIG. 4A) composed of a permanent magnet or a permanent magnet and a magnetic material (iron or iron-cobalt alloy) is inserted into a linear portion of an electron accelerator (or electron storage ring). It is useful as a device for generating strong radiation. An undulator, which is a typical example of the insertion light source, generates a sine-curve periodic magnetic field in the gap between the magnet rows (see FIGS. 4B and 4C). As shown in FIG. 5, general planar undulators include a hullback type (a) composed of only permanent magnets and a hybrid type (b) composed of permanent magnets and magnetic poles. In the present invention, the direction of the opposing magnet rows is called the air gap direction, and the direction of the electron orbit is called the axial direction.

[0003]

When the period length of the insertion light source becomes short and the thickness of the magnet becomes thin, various problems occur. For example, assuming a hull-back type insertion light source having a cycle length of 10 mm, the thickness of one magnet is as thin as 2.5 mm. In an insertion light source application, variations in the magnetic properties of individual permanent magnets cause large disturbances in the trajectories of the accelerated electrons. Therefore, it is necessary to minimize the variation in the residual magnetization and the variation in the angle of the permanent magnet. However, in the case of a magnet having a small thickness, several factors are superimposed, and the variation in magnetic characteristics becomes larger than before. These factors are as follows: 1) the relative variance of the magnet dimensional accuracy with respect to the thickness increases; 2) the volume ratio of the surface-degraded layer due to the magnet processing increases relatively; 3) the relative thickness variance of the corrosion-resistant coating increases. And so on. Problems also arise in terms of assembly accuracy. In the insertion light source, the gap distance between the opposed magnets is generally set to about half of the cycle length. In the case of an insertion light source having a cycle length of 10 mm, the gap distance is used at around 5 mm. Magnet dimensional accuracy is usually ± 0.05
Although it is about mm, there is a possibility that a magnetic field intensity variation of 2% width is given in the gap direction at the assembly stage, and an integrated magnetic field variation of about 4% is given in the electron traveling direction. Therefore, the dimensional accuracy of the magnet used in the short-period insertion light source of the present invention must be manufactured with a variation of 1/2 to 1/3 or less as compared with an insertion light source having a normal period length (30 mm or more). . In view of the above, in order to realize a short-period insertion light source having a period length of 10 mm or less, extension or improvement of the conventional method is not sufficient, and a proposal of a new technique is desired.

The inventor of the present invention solves this problem by, for example, periodically forming a cut in the magnet block 24 as shown in FIG. 6 and having a magnetization direction perpendicular to the original magnet block 24 at the cut. A short-period insertion light source has been proposed in which a plurality of composite magnets each including the magnets 30 and 50 are opposed to each other (Japanese Patent Application No. 9-095542). This feature is that thickness errors in the axial direction of the magnet are not easily accumulated. Because
Since a gap is formed by grinding and the position of the magnet in the gap direction and the position of the magnet in the axial direction are determined, even if the cycle length becomes short, the error of each magnet is not accumulated. However, the magnets to be inserted into these cuts are very thin and require a large number of magnets. Processing and assembly must be performed for each magnet, and it is strongly desired to improve such points. Was desired.

[0005]

The present inventors have conducted various studies to solve the above-mentioned problems. As a result, instead of inserting a large number of thin magnets at the breaks as described above, the present inventors periodically performed the breaks. The present invention was completed by combining a plurality of magnet blocks provided with. That is, the present invention
In an insertion light source having a period length of 10 mm or less, a cut is periodically provided in a magnet block, a magnet block having a magnetization direction perpendicular to the magnet block is periodically provided with a cut, and a composite magnet block obtained by combining these is provided. Are opposed to each other.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention realizes a short cycle length of 10 mm or less. Hereinafter, the production of the magnet block of the insertion light source of the present invention will be described in detail with reference to the drawings. 1A and 1B show an example of a magnet block of a planar undulator according to the present invention, wherein FIG. 1A is a top view, and FIG. 1B is a side view from the axial direction. The magnet blocks 1 and 9 correspond to one or more periods of the insertion light source. In FIG. 1, the magnet block 1 is in the gap directions 2 and 4, and the magnet block 9 is in the axial directions 3 and 5. It has an easy axis of magnetization. The magnet block 1 is formed by periodically forming a plurality of cuts (hereinafter, referred to as slits) 6a on a rectangular parallelepiped magnet block using a grinding wheel with a machine such as a forming grinder, and cutting the back side with a step 7a. . The magnet block 9 is provided with a slit 6b from the rectangular parallelepiped magnet block so as to engage with the slit 6a of the magnet block 1, and the step 7b is changed to the step 7a.
It is provided to engage with. After the comb-shaped teeth of the magnet blocks 1 and 9 are magnetized so that the N pole and the S pole are alternately formed, the magnet block 1 and the magnet block 9 are combined to form the composite magnet 19 of FIG. . This composite magnet constitutes a part of the insertion light source, and the composite magnet of FIG. 2 has five periods on one side of the insertion light source magnet row. A plurality of the composite magnets are opposed to each other and combined to form a magnet arrangement of the hull-back type insertion light source as shown in FIG.

At the time of manufacturing the composite magnet 19, the magnet block 1 already magnetized by a static magnetic field or a pulse magnetic field,
The magnet block 9 may be assembled with magnetized magnets,
Further, the unmagnetized magnet block 1 and the magnet block 9 are temporarily assembled into a composite magnet, and this is combined with a pulsed magnetic field.
It may be magnetized every time. The magnetized composite magnet 19 is inserted and held in a magnet cassette, and a plurality of these are combined to form an insertion light source. The magnetization of the composite magnet 19 may be performed before or after assembly. In the case where the magnetization is not assembled, it is necessary to incorporate the magnet block 9 having the magnetization perpendicular to the magnets 2 and 4 into the slit portion of the magnet block 1 while receiving the attraction or repulsion. On the other hand, when the magnetization is performed after the assembly, the non-magnetized magnet is magnetized after the composite magnet. In this case, a magnetizing magnetic field is applied in the direction of the gap magnetized magnet. At this time, the magnetized magnetic flux passes through the axial magnetized magnet to form a closed magnetic path. The magnetized magnet is also magnetized at the same time. Also, as already described, the magnets 3 and 5 of the slit portion are adjacent magnet portions 2 and 4.
In order to receive more attractive or repulsive force, the magnetized composite magnet block 19 is formed, and at the same time, positioning in the gap direction is performed by itself.

The peak intensity of the magnetizing magnetic field is 1.19 kA / m (15 kO / m
e) It is almost magnetized if above, but preferably 1.43kA / m
(18 kOe) is better. When magnetizing with a pulsed magnetic field, the width may be 500 μsec or more, preferably 2 msec.
It is better to have it. Of course, similar magnetization can be performed by an electromagnet that generates a static magnetic field, but the power supply becomes large-scale, which is not desirable.

The depth of the slit should be at least twice as large as the width of the comb-shaped magnet portions 2 and 3 of the magnet block, and more preferably three times as deep as the width.

If the material of the permanent magnet is a rare earth sintered magnet, a strong magnetic field can be formed in the air gap.
Any type of system (R is a rare earth element, the same applies hereinafter) may be used. However, when magnetizing after assembling with a pulse magnetic field, the RFeB system, which is easy to magnetize, is preferable.

Since the magnet block has a thickness of one cycle or more, there is no problem in holding the magnet by the cassette method as in the conventional case. As long as the cassette is non-magnetic, any of Al-based, SUS, brass, etc. may be used. Desirably, SUS having high sliding resistance is better.

When a short cycle length undulator is manufactured by combining a plurality of the magnet blocks, assuming a cycle length of 10 mm, 100 cycles can be obtained with a length of 1 m. Since the radiation light intensity of the undulator is ideally proportional to the square of the period number N, it is possible to generate very strong light with a compact accelerator ring.

[0013]

Next, an embodiment of the present invention will be described. [Example] An NdFeB-based sintered magnet block (Shin-Etsu Chemical Co., Ltd., N42H, magnetization direction 14 mm height direction) having a size of 40 mm x 25 mm x 14 mm was manufactured by a known method, and the magnet block was cut by 2 mm with an outer peripheral cutting machine. A magnet block 1 is provided with a gap of 2 mm in thickness, 10 mm in depth and a step of 15 mm at intervals.
Forty were produced. An NdFeB-based sintered magnet block of the same shape (manufactured by Shin-Etsu Chemical Co., Ltd., supra, magnetization direction 25 mm axial direction) is manufactured by a known method. A magnet block 9 was prepared by providing a slit having a thickness of 2 mm, a depth of 10 mm and a step of 15 mm.

A magnetizing head having magnetizing teeth for five periods was manufactured so that these magnet blocks could be magnetized by pulse at a time. The yoke was formed by laminating punched thin plates of pure iron having a thickness of 0.5 mm, and was wound. This magnetizing head is brought into contact with and facing the surface of the magnet block, and 4000V × 5000μF
This magnet block was pulse-magnetized by connecting it to a capacitor bank, but the peak magnetic field at this time was 1.59 kA / m
(20 kOe). A composite magnet 19 is formed by combining these magnet blocks 1 and 9 with SUS.
This composite magnet is housed in a non-magnetic cassette made of 316L material, 20 magnet cassettes are arranged, and a pair of magnet rows are opposed to each other. Was prepared. When the gap between the opposing magnet rows was set to 4 mm and the magnetic field distribution in the gap was measured with a small-area Hall element, it was confirmed that the peak magnetic field distribution was within 1.5% without adjusting the magnetic field. It was found that a magnetic field distribution was obtained.

[0015]

According to the present invention, in a short-period insertion light source having a period length of 10 mm or less, it is possible to reduce processing costs and assembly costs while maintaining magnetic field accuracy and magnet position accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic view of a magnet block of an insertion light source according to the present invention. (A) is a top view. (B) is a side view from the axial direction.

FIG. 2 is a schematic perspective view of a composite magnet of the insertion light source of the present invention.

FIG. 3 is a schematic side view of the insertion light source of the present invention.

FIG. 4A is a schematic perspective view of an undulator. (B) is the periodic magnetic field of (a). (C) is (a)
Electron orbit.

FIG. 5 is a schematic view of a basic magnet arrangement of a planar undulator, wherein (a) is a hullback type. (B) is a hybrid type.

FIG. 6 is an example of a magnet block of a conventional short cycle length undulator.

[Description of References] 1, 9 ‥‥‥‥ Magnet block 2, 4 ‥‥‥‥ Air-gap magnetized permanent magnet 3, 5 ‥‥‥‥ Axial magnetized permanent magnet 6a, 6b {Slit 7a, 7b} {Step 19} Composite magnet 20, 40} Air gap magnetized permanent magnet 24} Magnet block 30, 50} Axial magnetized permanent magnet 32} Pole piece

Claims (1)

[Claims] 1. An insertion light source having a period length of 10 mm or less,
It is characterized in that a cut is periodically formed in a magnet block, a cut is periodically formed in a magnet block having a magnetization direction perpendicular to the magnet block, and a plurality of composite magnet blocks obtained by combining these are opposed to each other. And insert light source.