JPH09320800A - Fixing method for magnet for insertion of light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely fix an inserting light source magnet of short periodic length to enhance position accuracy by directly fixing the insertion light source magnet of short periodic length to a yoke, and specifying the position in the stacking direction of the magnet by the position of the yoke. SOLUTION: An insertion light source magnet 20 is formed by alternately stacking magnets 21, 21a, 21b, having vertical magnetizing direction (Y-direction) and magnets 22 having horizontal magnetizing direction (Z-direction) on the space surface. The width of the vertical magnetizing magnets 21, 21a, 21b is larger than the width of the horizontal magnetizing magnet 22, step difference 35 is formed in a magnet fixing yoke 30 according to the width, and the magnet 20 is fixed to the fixing yoke 30 and a base plate 40. Even if the periodic length is short, 4-20mm, the magnet is fixed by varying the step difference 35 of the magnet fixing yoke 30. Three magnets are fixed to a frame stopper 50, so that the magnet 20 does not extend out into the space side of the fixing yoke 30. As a result, the insertion light source magnet 20 having 4-20mm periodic length is surely fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fixing a magnet for an insertion light source.

[0002]

2. Description of the Related Art An insertion light source composed of a permanent magnet or a permanent magnet and a magnetic material (iron or iron-cobalt alloy) (FIG. 2 (a))
Is inserted into the linear portion of the electron accelerator (or the electron storage ring) so as to sandwich the vacuum chamber, and generates a sinusoidal periodic magnetic field in the space between the magnet rows (see FIG. 2).
(B)). As shown in FIG. 2 (c), high-speed electrons moving in the accelerator make a meandering motion by the periodic magnetic field and generate synchrotron radiation from each meandering point (Halbach, Nuclear Instrument).
s and Method 187, (1981), page 109). There are wiggler mode and undulator mode depending on the degree of meandering. In the Wiggler mode, the emitted light generated from each meandering point is superposed, and the emitted light with a power 10 to 1000 times higher than that emitted from the deflecting electromagnet is obtained. On the other hand, in the undulator mode, the synchrotron radiation generated by each meandering motion interferes with each other, and the fundamental wave and its higher-order light are more volatile than the wiggler light.
A strong light can be obtained about 10 to 1000 times. Wiggler mode or undulator mode can be classified by a parameter called K value. When the K value is around 1 or less, the undulator mode is set, and when the K value is higher, the wiggler mode is set. In the present invention, these are collectively referred to as an undulator or an insertion light source.

As shown in FIG. 3, the insertion light source is roughly divided into a hull back type (see FIG.
There are two types, (a)) and a hybrid type (FIG. 3B) composed of a permanent magnet and magnetic poles. Both show almost the same magnetic field strength and distribution, and there is no big difference. However, in general, the weight of the magnet used in the hybrid type is often smaller. At the initial stage of the development of the insertion light source, the angle and characteristics of the permanent magnet varied greatly, so the magnetic field strength of the hybrid type was easier than that of the hullback type. Recently, the variation of permanent magnets is small and the characteristics are uniform, and the method of recombination of magnet pairs has been introduced and improved. Therefore, almost the same magnetic field distribution can be obtained by either method. The deviation of the electron orbit when the air gap is changed is small because the Halbach type has almost linearity, but the hybrid type is non-linear, so the deviation easily occurs.

The insertion light source as shown in FIG. 3 is of a general type called a plane undulator. In order to fix the magnet of the planar undulator (Hullback type / hybrid type) shown in FIG. 3, the magnet / cassette shape as shown in FIG. 4 is generally used, and the cassette 60 is mechanically or adhesively used, or The magnet 20 is fixed by using both of them together. Basically, the magnet can be mechanically fixed, which is a highly reliable fixing method. Further, the magnetic field can be adjusted by providing the adjustment hole 70 on the side surface or the bottom surface of the cassette. Since the cassette can be processed with a milling machine or a lathe, dimensional accuracy is relatively easy to obtain. Although the positioning accuracy of the magnet in the stacking direction is important, the positioning accuracy can be obtained by ensuring the accuracy of the cassette and the stop hole. For this reason, a fixing method using a cassette is generally used.

[0005]

However, when the cycle length becomes shorter and the magnet thickness becomes thinner, the cassette fixing method becomes difficult. This is because the width of the top stopper 50 that suppresses the magnet 20 from jumping out in FIG. 4 becomes smaller, and only a small screw for fixing this to the cassette can be used. For example, in a Hullback type insertion light source with a cycle length of 20 mm,
The thickness of one magnet is 5 mm, and the thickness of the cassette that houses the magnet is also 5 mm. With a thickness of 5 mm, only M3 bolts can be used at most for fixing the top to fix the magnet, and M2 bolts are preferable in consideration of machining and the size of the bolt head.
However, since the attraction force between the opposing magnets is large, the bolt of M2 cannot stop the magnet sufficiently. Here, although it is possible to stop the magnets directly on the base without using a cassette, a repulsion / rotational force acts between the magnets, so when the magnets are stacked, a gap is likely to be formed between the magnets. Therefore, the positioning of the magnet in the stacking direction is not sufficient, and an error is likely to occur in the magnetic field strength distribution of the air gap. From the above points, there has been a demand for a magnet fixing method in which magnets are surely fixed by an undulator having a short cycle length and the laminated magnets are easily positioned.

[0006]

The present invention has a cycle length of 4 to 4.
It is intended to provide a magnet fixing method for reliably fixing a magnet of an undulator having a short cycle length of 20 mm to improve position accuracy. That is, the present invention provides a method for fixing a magnet for an insertion light source having a period length of 4 to 20 mm, in which a magnet or a magnetic material is directly fixed to a magnet fixing yoke or a drive frame, and the position of the magnet in the stacking direction is fixed to the magnet. The gist of the invention is a method of fixing a magnet for an insertion light source, which is determined by the position of the use yoke or the mount. This will be described in more detail below.

[0007]

Embodiments of the present invention will be described below. As mentioned above, the conventional non-magnetic cassette 1
One magnet was placed in each piece, and the magnets were laminated by fixing the cassette. However, in the present invention, the magnet or the magnetic material is directly fixed to the mounting yoke or the pedestal for the inserted light source having the period length of 4 to 20 mm, and the cassette for each magnet is not used.

An example of an embodiment of the present invention will be described with reference to FIG. 1 by taking a hull back type as an example. FIG. 1A is a schematic view of the Hullback type undulator viewed from the Z-axis direction, and FIG. 1B is a schematic view of the Halbach-type undulator. The magnet 20 has a magnet 21 having a vertical magnetization direction (Y direction) and a magnet 22 having a horizontal magnetization direction (Z direction) alternately stacked on the void surface. In FIG. 1B, the width of the vertically magnetized magnet 21 (width in the X-axis direction of the surface where the magnets are in contact with each other) is larger than the width of the horizontally magnetized magnet 22, and accordingly, the step 3 is formed on the magnet fixing yoke 30.
5 is provided, and the magnet 20 is provided as shown in FIG.
Are fixed to the fixed yoke 30 and the base plate 40. FIG.
Since the cycle length is 20 mm, the steps 35 are every 5 mm. The left and right fixed yokes 31 and 32 are provided with a step for each magnet thickness according to the magnet width.
It should be about mm.

Since the stacking position of the magnet 20 is determined by the step 35, the position irregularity does not overlap when the magnets are stacked, and the stacking positioning is performed within the variation range of the magnet thickness and the machining / assembly accuracy of the fixed yoke. . Therefore, even if the cycle length is short and 4 to 20 mm, the step 35 of the magnet fixing yoke 30 may be changed, and there is no problem in positioning in the stacking direction. It is possible to provide a step for each magnet on the base plate 40, and the same effect as providing a step on the fixed yoke 30 can be expected, and each step may be performed alone or in combination.

Further, the top stopper 50 for fixing the magnet 20 so that the magnet 20 does not jump out from the fixed yoke 30 toward the air gap side suppresses three magnets in FIG. The width of the frame stopper is effectively equivalent to the thickness of two magnets, but both ends are magnets 21a, 2
Since it hangs half on 1b, 3 magnets 22, 2
1a and 21b are suppressed. This makes it possible to use the top stopper 50 having a width of two magnets, and the M51 bolt 51 or larger. Therefore, even if the thickness of the magnet is reduced, the magnet can be sufficiently fixed. In FIG. 1, only the vertically magnetized magnets 21 are extracted, and it is intended to insert a magnet or a magnetic material at the bottom and adjust the magnetic field. Therefore, by removing the pair of left and right top stops 50, the horizontally magnetized magnets 22 on both sides are removed. It is possible to pull out the perpendicular magnetizing magnet 21 while being fixed by the adjacent frame stopper. In FIG. 1B, three magnets are suppressed by one top stopper 50, but in the present invention, two or more magnets may be fixed.

By combining the yoke / coma fixing structure and the magnet as described above, the positioning in the stacking direction can be reliably performed even when the cycle length is short, and the magnet can be securely pressed. According to the magnet fixing method of the present invention, the cycle length is 2
An insertion light source of 0 mm or less is possible, and a fixing method of the present invention can be realized up to a cycle length of about 4 mm. At a cycle length of 4 mm or less, the magnet thickness is 1 mm or less, which causes difficulties in magnet manufacturing. Below this, it is practical to consider a different fixing method together with the magnet manufacturing method. Is.

[0012]

According to the present invention, in an undulator having a small magnet thickness and a short cycle length, the magnet can be securely fixed and assembled.

[Brief description of drawings]

FIG. 1 is a schematic view of a method of fixing a magnet for an insertion light source according to the present invention, in which (a) is a view seen from the Z-axis direction and (b) is a view seen from the Y-axis direction.

FIG. 2 is a schematic view of an insertion light source used in the present invention,
(A) is an insertion light source of an undulator structure, (b) is a periodic magnetic field in (a), (c) is a schematic diagram of the electron orbit in (b).

FIG. 3 is a schematic diagram of a magnetic circuit structure of an undulator. (A) is a hull back type, (b) is a hybrid type.

FIG. 4 is a schematic diagram of a method of fixing a magnet by stopping a frame in an undulator.

[Explanation of symbols]

 20 permanent magnets 21, 21a, 21b vertical (Y direction) magnetizing magnets 22 horizontal (Z direction) magnetizing magnets 30, 31, 32 yokes 35 yoke step 40 base plate 50 frame stopper 51 bolts 60 cassette 70 adjustment hole

Claims (3)

[Claims] 1. A method of fixing a magnet for an insertion light source having a period length of 4 to 20 mm, wherein a magnet or a magnetic material is directly fixed to a magnet fixing yoke or a drive frame, and the position of the magnet in the stacking direction is fixed to the magnet. Method for fixing an insertion light source magnet, characterized in that it is determined by the position of the mounting yoke or the mount. 2. The magnet or magnetic material having a magnetization parallel to the magnet stacking direction and the magnet or magnetic material having a magnetization perpendicular to the magnet stacking direction have different widths, and the fixed yoke is fitted to the magnet or the magnetic material. The method for fixing the magnet for the insertion light source according to claim 1, wherein the magnet for the insertion light source is installed so as to restrain the magnet width direction and restrain the magnet or magnetic material protrusion in the air gap direction. 3. Two pieces are provided by one frame stopper on the fixed yoke.
The method for fixing a magnet for an insertion light source according to claim 1 or 2, wherein at least one magnet is constrained.