JP3260079B2 - How to fix the insertion light source magnet - Google Patents

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 comprising a permanent magnet or a permanent magnet and a magnetic material (iron or iron-cobalt alloy) (FIG. 2A)
2) is inserted into the linear portion of the electron accelerator (or electron storage ring) with the vacuum chamber interposed therebetween, and generates a sine-curve periodic magnetic field in the gap between the magnet rows (FIG. 2).
(B)). As shown in FIG. 2 (c), the high-speed electrons rotating in the accelerator make a meandering motion by the periodic magnetic field, and emit light from each meandering point (Halbach, Nuclear Instrument).
s and Method 187, (1981), p. 109). There are wiggler mode and undulator mode depending on the degree of meandering. In the wiggler mode, the radiated light generated from each meandering point is superimposed, and the radiated light from the bending electromagnet is 10 to 100
Emission light having 0 times higher power is obtained. On the other hand, in the undulator mode, the radiated light generated from each meandering motion interferes with each other, and the fundamental wave and its higher-order light can obtain light that is about 10 to 1000 times stronger than the wiggler light. The wiggler mode or the undulator mode can be classified by a parameter called a K value. When the K value is around 1 or less, the undulator mode is set. When the K value is more than 1, the wiggler mode is set. In the present invention,
These are collectively called an undulator or an insertion light source.

As shown in FIG. 3, the insertion light source can be roughly classified into a hull-back type (FIG. 3) comprising only permanent magnets.
(A)) and a hybrid type (FIG. 3 (b)) composed of permanent magnets and magnetic poles. Both show almost the same magnetic field strength and distribution, and there is no significant difference. However, in general, the hybrid type often uses less magnet weight. In the initial stage of the development of the insertion light source, the angle of the permanent magnets and the variation in characteristics were large, so that the hybrid type was easier to align the magnetic field intensity than the Halbach type. In recent years, the dispersion of the permanent magnets is small, the characteristics are uniform, and the method of rearranging the magnet pairs has been introduced and improved, so that almost the same magnetic field distribution can be obtained by either method. The displacement of the electron orbit when the air gap is changed is small in the Halbach type because the linearity is almost satisfied, but is likely to occur in the hybrid type due to the non-linearity.

An 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 (Halbach type / hybrid type) shown in FIG. 3, a magnet / cassette shape as shown in FIG. 4 is generally used, and the cassette 60 is mechanically or adhesively bonded, or The magnet 20 is fixed by using both of them. This is a highly reliable fixing method because the magnet can be basically fixed mechanically. Further, by providing the adjustment holes 70 on the side and bottom surfaces of the cassette, it is possible to adjust the magnetic field. Since the cassette can be processed by a milling machine or a lathe, dimensional accuracy is relatively easily obtained. In particular, the positioning accuracy of the magnets in the stacking direction is important, but the positioning accuracy can be obtained by securing the cassette and the stop hole accuracy. For this reason, a fixing method using a cassette is generally used.

[0005]

However, as the cycle length becomes shorter and the magnet thickness becomes thinner, difficulties arise in the cassette fixing method. This is because the width of the frame stopper 50 for suppressing the protrusion of the magnet 20 in FIG. 4 is reduced, and only a small screw for fixing this to the cassette can be used. For example, in a hull-back type insertion light source having a cycle length of 20 mm, the thickness of one magnet is 5 mm, and the thickness of a cassette for accommodating the magnet is also 5 mm. With a thickness of 5 mm, only M3 bolts can be used for fixing the magnet at the top, and M2 bolts are better in consideration of machining and the size of the bolt head. However, since the attraction force between the opposing magnets is large, the magnet is not sufficiently stopped with the M2 bolt. Here, it is possible to stop the magnet directly on the base without using a cassette, but since repulsion and rotational force act between the magnets, a gap is easily formed between the magnets when the magnets are stacked.
Therefore, the positioning of the magnet in the stacking direction is not sufficient, and an error is easily caused in the magnetic field intensity distribution in the air gap. In view of the above, it is an object of the present invention to provide a magnet fixing method in which a magnet is securely fixed by an undulator having a short cycle length and the positioning of the stacked magnets is easy.

[0006]

According to the method for fixing a hull-back type insertion light source magnet of the present invention, a method for fixing an insertion light source magnet having a period length of 4 to 20 mm, wherein the magnet is mounted on a magnet fixing yoke or a driving base. Directly fixed and the position of the magnet in the stacking direction is determined by the position of the magnet fixing yoke or the gantry, and one magnet on the fixed yoke restrains three magnets, one of which is completely restrained. The remaining two are restrained in half. Of the magnets fixed by frame stop, the magnetization direction of one magnet completely constrained is parallel to the electron trajectory, and the magnetization directions of two magnets constrained in half are perpendicular to the electron trajectory. It is preferred that

[0007]

Embodiments of the present invention will be described below. As described above, the conventional non-magnetic cassette 1
One magnet was placed in each piece, and the cassettes were fixed to each other to stack the magnets. However, in the present invention, 4 to 20 mm
For the insertion light source having a periodic length, a magnet is fixed directly to a mounting yoke or a mount, and a cassette for each magnet is not used.

Referring to FIG. 1, an example of an embodiment of the present invention will be described. FIG. 1A is a schematic diagram of the hullback undulator as viewed from the Z-axis direction, and FIG. The magnet 20 has a magnetizing direction (Y direction) perpendicular to the gap plane and a magnetizing direction (Z direction) parallel to the electron orbit.
Direction) are alternately stacked. FIG.
In (b), the width of the perpendicular magnetized magnet 21 (the width in the X-axis direction of the surface where the magnets are in contact with each other) is smaller than the width of the horizontal magnetized magnet 22, and a step 35 is provided on the magnet fixed yoke 30 in accordance with this. As shown in FIG. 1A, the magnet 20 is fixed to the fixed yoke 30 and the base plate 40. In FIG. 1, since the cycle length is 20 mm, the steps 35 are every 5 mm. The left and right fixed yokes 31, 32 are provided with a step for each magnet thickness in accordance with the magnet width, and the step is 1 m.
m is sufficient.

Since the position of lamination of the magnets 20 is determined by the step 35, when the magnets are laminated, irregularities in the positions do not overlap, and the lamination positioning is performed within the range of variation in the magnet thickness and the processing and 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 also possible to provide a step for each magnet on the base plate 40, and the same effect as providing a step for the fixed yoke 30 can be expected. Each step may be performed alone or used in combination.

The frame stopper 50 for fixing the magnet 20 so as not to protrude from the fixed yoke 30 to the gap side suppresses three magnets in FIG. The width of the stop is effectively equivalent to the thickness of the two magnets, but both ends are magnets 21a and 2a.
1b, three magnets 22, 2
1a and 21b are suppressed. This makes it possible to use a stop 50 having a width of two magnets, and a bolt 51 of M5 or more can be used. Therefore, the magnet can be sufficiently fixed even when the magnet thickness is reduced. If it is intended to adjust the magnetic field by extracting only the horizontal magnetized magnet 22 and inserting a magnet or magnetic material at the bottom, the pair of left and right vertical magnetized magnets 21 can be removed by removing the pair of left and right frame stoppers 50. The horizontal magnetized magnet 22 can be extracted while being fixed by the stopper. In this case, since the horizontal magnetized magnet receives a force from the surrounding magnets in the direction of pressing against the base plate in the assembled state, it does not jump out even if the frame stopper 50 is removed. Conversely, when the magnetic field is adjusted by extracting the perpendicular magnet 21, the pair of left and right frame stoppers 50 are removed, and the horizontal magnet 22 to which the ejecting force is not applied is pressed by an appropriate method so as not to eject. Above, by removing the adjacent frame stopper (for example, 51), the perpendicular magnetized magnet 21a can be safely taken out.

By the combination of the yoke / frame stopper structure and the magnet as described above, the positioning in the stacking direction can be reliably performed even if the period length is short, and the magnet can be reliably pressed. According to the magnet fixing method of the present invention, the period length is 2
An insertion light source of 0 mm or less is possible, and a period length of about 4 mm can be realized by the fixing method of the present invention. If the cycle length is 4 mm or less, the magnet thickness will be 1 mm or less, which causes difficulties in magnet fabrication. Below this, it is practical to consider another fixing method together with the magnet fabrication method. It is.

[0012]

According to the present invention, it is possible to reliably fix and assemble a magnet in an undulator having a small magnet thickness and a short period length.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic views of a method of fixing a magnet for an insertion light source according to the present invention, wherein FIG. 1A is a view seen from a Z-axis direction, and FIG.

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

FIG. 3 is a schematic diagram of a magnetic circuit structure of an undulator. (A) is a hullback type, and (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]

 DESCRIPTION OF SYMBOLS 20 Permanent magnet 21, 21a, 21b Vertical (Y direction) magnetized magnet 22 Horizontal (Z direction) magnetized magnet 30, 31, 32 Yoke 35 Yoke step 40 Base plate 50 Top stop 51 Bolt 60 Cassette 70 Adjustment hole

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-116238 (JP, A) JP-A-9-213499 (JP, A) JP-A-6-68400 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) H05H 13/04

Claims (2)

(57) [Claims] 1. A method for fixing a magnet for an insertion light source having a period length of 4 to 20 mm, wherein the magnet is directly fixed to a magnet fixing yoke or a drive base, and the position of the magnet in the stacking direction is set to the magnet fixing yoke or Determined by the position of the stand,
One stop on the fixed yoke restrains three magnets, one of which is completely restrained, and the other two are half and half.
A method for fixing a magnet for a hull-back type insertion light source, wherein the magnet is constrained. 2. A magnet fixed by frame stop,
Claim the magnetization direction of the one magnet is completely constraints Ri parallel der the electron orbit, the magnetization direction of two magnets that are constrained by half characterized in that it is a direction perpendicular to the electron orbitals 2. The method for fixing the hull-back type insertion light source magnet according to item 1.