JP2002246199A - Insertion-type polarization generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insertion-type polarization generator which solves the problem of thermal demagnetization, caused by a magnet line being heated accompanying the passage of electron beams. SOLUTION: This insertion-type polarization generator is equipped with a first magnet line 2, in which many magnets are arranged in a line; a second magnet line 3 in which many magnets are arranged in a line, installed opposite to the first magnet line 2; a gap space through which electron beams are passed, formed between the first magnet line 2 and the second magnet line 3; and a vacuum tank 1 vacuum sealing the first magnet line 2 and the second magnet line 3. A foil 25 of high thermal conductivity is fit to each facing surface of the first magnet line 2 and the second magnet line 3 for radiating heat generated in the magnet lines 2, 3. The foil 25 is preferably formed in a double-layer structure of copper and nickel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insertion type polarization generator in which opposing magnet arrays are vacuum-sealed in a vacuum chamber.

[0002]

2. Description of the Related Art When an electron beam accelerated to near the speed of light in a vacuum is bent in a magnetic field, it emits radiated light in the tangential direction of the movement trajectory of the electron beam, which is called synchrotron radiation. A light source that generates such synchrotron radiation light is installed on a straight line portion of an electron storage ring (electron beam storage ring), and various technologies utilizing characteristics such as high directivity, high intensity, and high deflection are put to practical use. Research is being carried out for conversion. Today's electron storage rings are equipped with an insertion type undulator which is a high intensity light source with higher beam current and smaller beam cross section.

This insertion type polarization generator has a first magnet row in which a large number of magnets are arranged in a row, and a first magnet row provided in opposition to the first magnet row, and a large number of magnets arranged in a row. Two magnet rows, a gap space for passing an electron beam formed between the first magnet row and the second magnet row, and vacuum sealing the first magnet row and the second magnet row And a vacuum chamber. When the electron beam passes through the vacuum gap space, the synchrotron radiation light described above is generated.

[0004]

However, there is a problem that the magnet array is heated as the electron beam passes. When the magnet is heated and heat is stored, the magnetic properties are degraded due to thermal demagnetization. When the magnetic properties deteriorate,
The state of the magnetic field in the gap space also deteriorates, and there is a possibility that desired synchrotron radiation cannot be obtained.

There is also known an insertion type polarization generator in which only a gap space is covered with a vacuum chamber and a magnet row opposed to the gap space is disposed in the atmosphere. In such a configuration, the problem of thermal demagnetization does not occur so much. But,
In the case of a configuration in which the magnet rows facing each other are also sealed in a vacuum chamber,
Since the gap space is set narrow, the problem of thermal demagnetization cannot be ignored.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to solve the problem of thermal demagnetization caused by heating of a magnet array with the passage of an electron beam. It is to provide a device.

According to the present invention, there is provided an insertion type polarized light generator comprising: a first magnet row in which a number of magnets are arranged in a row; and a first magnet row opposed to the first magnet row. A second magnet row in which a number of magnets are arranged in a row, a gap space for passing an electron beam formed between the first magnet row and the second magnet row, A vacuum chamber for vacuum-sealing the first magnet row and the second magnet row, and a sheet material having good thermal conductivity is attached to each of the opposing surfaces of the first magnet row and the second magnet row. , Wherein the heat generated in each of the magnet rows is released. According to this configuration, the first
A sheet material having good thermal conductivity is attached to each of the opposing surfaces (the side facing the gap space) of the magnet row and the second magnet row. Even when the magnet is heated by the passage of the electron beam, the heat is transmitted through the sheet material and escapes. Therefore, the heat does not accumulate in the magnet and the magnetic characteristics do not deteriorate. as a result,
It is possible to provide an insertion-type polarization generator that can solve the problem of thermal demagnetization due to heating of a magnet row as an electron beam passes.

In a preferred embodiment of the present invention, the sheet material is formed of copper.
Copper is a material having good thermal conductivity, and can efficiently release the heat accumulated in the magnet.

In another preferred embodiment of the present invention, the sheet material is formed in a two-layer structure of copper and nickel. The sheet material is preferably in close contact with the surface of the magnet row. If the gap between the gaps is set to be small and the sheet-like material floats from the surface of the magnet row, the electron beam may collide with the sheet-like material, which is not preferable. Therefore, when the sheet material has a two-layer structure of copper and nickel, nickel can be attached in a state of being in close contact with the surface of the magnet row because nickel is a magnetic material. Thereby, it is possible to prevent the sheet-like material from rising from the magnet surface.

[0009] In still another preferred embodiment of the present invention,
An example is provided in which an adjusting mechanism for adjusting the tension when attaching the sheet material is provided. As described above, the sheet-like material needs to be in close contact with the surface of the magnet row. Therefore, by providing an adjusting mechanism for adjusting the tension at the time of attaching the sheet-like material, it is possible to attach the sheet-like material in a state where it is taut with an appropriate tension.

[0010] In still another preferred embodiment of the present invention,
A fixing member for fixing a longitudinal end of the sheet material is provided, and the tension is adjusted by moving the fixing member along the longitudinal direction. Even when the sheet-like material is pulled, it is preferable that the sheet-like material can be uniformly pulled. Thus, by fixing the longitudinal end portion of the sheet material by a fixing member and moving the fixing member along the longitudinal direction, the sheet material can be pulled uniformly over the entire region in the width direction. Thereby, appropriate tension can be applied to the entire sheet material.

[0011] In still another preferred embodiment of the present invention,
The magnet may be an Nd-Fe-B-based rare earth magnet.

Nd-Fe-B rare earth magnets have excellent magnetic properties and are suitable for a magnetic circuit for obtaining synchrotron radiation. However, there is an aspect that it is weak to heat. Therefore, when the above-mentioned magnet is used, it can be said that the configuration according to the present invention is particularly suitable.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <Structure of undulator> A preferred embodiment of a vacuum-sealed undulator (insertion type polarization generator) according to the present invention will be described with reference to the drawings. Figure 1
FIG. 3 is a cross-sectional view of the undulator.

A first magnet row 2 and a second magnet row 3 face each other inside a vacuum chamber 1 with a gap space G interposed therebetween. The gap space G is a passage through which the electron beam B passes,
The electron beam B travels in a direction perpendicular to the paper. The first and second magnet rows 2 and 3 also have a large number of magnets arranged side by side along the direction perpendicular to the plane of the drawing. First and second magnet rows 2,
3 are both sealed inside the vacuum chamber 1. A vacuum pump (not shown) is connected to the vacuum chamber 1. Each magnet row 2, 3 is mounted and supported by a magnet row support 4, and this magnet row support 4 is mounted and supported on an I-beam 7 via a lifting shaft 5 or the like. This I-beam 7
The first and second magnet rows 2 and 3 can be moved up and down by a vertically moving mechanism (not shown). That is, the gap interval of the gap space G can be adjusted. The mechanism for supporting and driving the first magnet row 2 and the mechanism for supporting and driving the second magnet row 3 are the same.

<Structure of Magnet Unit> FIG. 2 is a view showing the structure of a magnet unit 20 which is a structural unit of each of the magnet rows 2 and 3. This magnet unit 20 includes a permanent magnet 21 and
It comprises a holder 22 for holding a permanent magnet 21, a permanent magnet holding member 23, and a foil holding member 24. A concave portion 22a is formed in the holder 22, and the permanent magnet 21 is placed in the concave portion 22a.
The permanent magnet 21 is fixed to the holder by the third holding claw 23a. The permanent magnet holding member 23 can be fixed to the holder 22 by pulling it from the back side of the holder 22 with a bolt (not shown).

As the permanent magnet, an Nd-Fe-B rare earth magnet is preferably used. For example, US Pat.
Rare earth magnets disclosed in U.S. Pat. Nos. 0,723 and 4,792,368 can be used. The holder 22 is preferably made of oxygen-free copper. A foil 25 is attached to the surface of the permanent magnet 21 and a foil holding member 24 for holding both sides in the width direction of the foil 25 is provided. This will be described later. <Mounting Support Structure for Magnet Row> Next, the mounting support structure for the magnet row will be described. FIG. 3 shows the second magnet row 3 (the same applies to the first magnet row 2, so hereinafter simply referred to as “magnet row”).
That. FIG. 2 is a perspective view of FIG. FIG. 4 is a perspective view of the magnet row support 4 that supports the magnet rows, as viewed from the back side (the opposite side that does not face the gap space). FIG.
FIG. 3 is a front view of the magnet row mounting structure as viewed from the traveling direction of the electron beam. FIG. 6 is a side view of the magnet row mounting structure.

As shown in FIG. 3 and the like, in order to form the magnet rows 3 along the traveling direction of the electron beam, a large number of magnet units 20 shown in FIG. 2 are arranged in the traveling direction of the electron beam. The magnet unit 20 is fixed to a magnet mounting beam 40 having a horizontal H-shaped cross section. Each magnet unit 20 is attached to a mounting surface 40 a by two bolts 41.
It is fixed to be attracted to. The magnet mounting beam 40 constitutes the magnet row support 4, but is not limited to the illustrated structure. For example, the magnet array support 4 may be configured by combining a plurality of members. In addition, what is necessary is just to employ | adopt a well-known structure about the magnetization direction of each magnet which comprises the magnet row 3, For example, the magnetization direction of the main magnet row disclosed in Unexamined-Japanese-Patent No. 2000-206296 by the present applicant. May be the same as

A foil 25 (corresponding to a sheet-like material) is attached to the surface of the magnet row 3 (the surface facing the gap space). However, no adhesive is used to attach the foil 25. This foil 25
Is for releasing the heat accumulated in the magnet as the electron beam passes through the gap space. Foil 2
5 is formed of a material having good thermal conductivity, the base is copper,
It has a two-layer structure with nickel plating on it. Note that nickel cladding may be used instead of nickel plating. Copper is a material with good thermal conductivity, which allows heat to escape quickly. Of course, a material having good thermal conductivity other than copper (for example, having a thermal conductivity of 1 W / cm · de)
g or more). Further, by providing the nickel layer, the adhesion to the surface of the magnet row 3 can be improved. That is, in the two-layer structure, the foil 25 is attached so that the nickel layer is on the surface side of the magnet row 3 and the copper layer is on the gap space side.

As a preferable material for forming a permanent magnet, an Nd-Fe-B-based rare earth magnet has been described. However, this magnet has an advantage that its magnetic properties are superior to other types of magnets. However, it has a disadvantage that it is weak to heat as compared with other magnets. Therefore, the magnetic characteristics can be maintained by dissipating heat by the foil 25.

The thickness of the foil 25 is 50 μm to 100 μm.
m is preferable. If the thickness is 50 μm or less, the film may be cut when tension is applied. Also, 10
If the thickness exceeds 0 μm, heat in the magnet cannot be quickly radiated.

The foil 25 is formed in a longitudinal shape extending in the traveling direction of the electron beam, one end of which is fixed,
The other end is configured to be adjustable by the adjustment mechanism 10 (see FIG. 4). The adjusting mechanism 10 is provided for adjusting the tension at the time of attaching the foil 25 to be appropriate. As shown in FIGS.
Is bent at 90 ° at the end of the magnet array 3 at the position of the magnet unit 20, and closely adheres to the side end surface 40 b of the magnet attachment beam 40, and further, the magnet attachment beam 4.
It is bent again by 90 ° toward the back side of 0. The ends of the foil 25 are the first fixing member 11 and the second fixing member 1.
2 fixed. That is, the end of the foil 25 is sandwiched between the first fixing member 11 and the second fixing member 12, and is fixed by screwing the second fixing member 12 to the first fixing member 11 with the bolt 13. You. The fixing members 11 and 12 are configured to be movable in the direction of arrow A in FIG. 4 (along the longitudinal direction of the foil 25).
The mechanism for this will be described. Magnet mounting beam 4
An adjustment table 14 is fixedly attached to the back surface of the unit 0 with two bolts 15. The fixing members 11 and 12 can be moved in the direction of arrow A by rotating two adjustment screws 16 provided on the adjustment table 14. Elongated holes 17 are formed at both ends of the first fixing member 11 along the moving direction.
8 are provided. Thereby, the fixing members 11 and 12
Can be moved smoothly.

By providing the adjusting mechanism 10 as described above, the foil 25 can be attached to the magnet surface with an appropriate tension. The reason why the adhesion between the foil 25 and the magnet surface is improved is that if the foil 25 is lifted off the magnet surface, the foil 25 may collide with the electron beam and cause a problem. Further, when the foil 25 is pulled, the foil 25 is pulled via the fixing members 11 and 12, so that the foil 25 can be pulled with a uniform tension over the entire area in the width direction of the foil 25. By bringing the foil 25 into close contact with the magnet surface,
It is possible to reduce the gap interval (for example, about several mm).

As shown in FIG. 3, both ends in the width direction of the foil 25 are pressed by a foil pressing member 24. This foil holding member 24 is also a magnet unit 2
0 is fixed to the magnet unit 20 so as to be attracted by bolts (not shown) from the back surface side. This makes it possible to prevent the foil 25 from rising at both ends in the width direction. As shown in FIG. 3, the number of the provided foil holding members 24 is sufficient for every few magnet units 20. As shown in FIG. 5, a pipe 42 for flowing hot water
The pipe 42 is attached to the magnet attachment beam 40 by a holding member 43 and a bolt 44. One end of the foil 25 can be adjusted by the adjusting mechanism 10 as shown in FIG. 4, but the other end (not shown) need not be provided with an adjusting mechanism and may be fixed. As for the way of fixing, it can be fixed by a method of providing a fixing member as shown in FIG.

<Assembly Procedure> First, the magnet units 20 are sequentially mounted on the magnet mounting beam 40. Next, one end of the foil 25 is fixed. The foil 25 is attached along the surface of the magnet row 3. In this attaching step, it is preferable to use a holding jig for pressing the foil 25 against the magnet surface. By using this holding jig, the foil 25 can be attached in order from the end so that the foil 25 does not rise. In this attaching step, both sides of the foil 25 are appropriately pressed by the foil pressing member 24. Further, the other end of the foil 25 is attached by the adjusting mechanism 10 while adjusting the tension. When the pressing by the foil pressing member 24 is completed for the entire area through which the electron beam passes, the attaching step is completed. According to the present invention, as shown in FIGS. 3 and 4, the side end face 40b has only a thin foil, so that the undulators manufactured according to the present invention can be joined in a row. For example, undulators having a length of 5 m are connected in a row, and 2
A long undulator of 0 m or more can be manufactured.

When combining several magnet rows,
By adhering the foil 25 as shown in FIG. 3, the magnet rows can be arranged without gaps. That is, since the foil 25 is brought into close contact with the side end surface 40b and is turned to the back surface, the magnet rows can be closely arranged.

<Another Embodiment> The magnet unit and the support mechanism of the magnet unit are not limited to the configuration of the present embodiment. The shape of the sheet material is not limited to that of the present embodiment.

In the present embodiment, the adjusting mechanism is provided only at one end of the sheet material, but the adjusting mechanism may be provided at both ends of the sheet material.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of an undulator.

FIG. 2 is a diagram showing a configuration of a magnet unit.

FIG. 3 is a perspective view of the magnet array viewed from above.

FIG. 4 is a perspective view of the magnet row support as viewed from the back side.

FIG. 5 is a front view of the magnet row mounting structure viewed from a traveling direction of an electron beam.

FIG. 6 is a side view of the magnet row mounting structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum tank 2 1st magnet row 3 2nd magnet row 4 Magnet row support 10 Adjustment mechanism 11 1st fixing member 12 2nd fixing member 20 Magnet unit 21 Permanent magnet 40 Magnet mounting beam G Gap space B Electron beam

Claims (6)

[Claims] A first magnet row in which a number of magnets are arranged in a row; a second magnet row provided in opposition to the first magnet row and in which a number of magnets are arranged in a row; A gap space through which an electron beam formed between the first magnet row and the second magnet row passes, and a vacuum chamber for vacuum-sealing the first magnet row and the second magnet row. An insert characterized in that a sheet-like material having good thermal conductivity is attached to each of the opposing surfaces of the first magnet row and the second magnet row, and heat generated in each magnet row is released. Type polarization generator. 2. The insertion type polarization generator according to claim 1, wherein the sheet-like material is formed of copper. 3. The insertion type polarization generator according to claim 1, wherein the sheet-like material has a two-layer structure of copper and nickel. 4. The insertion type polarization generator according to claim 1, further comprising an adjusting mechanism for adjusting a tension when attaching the sheet material. 5. A fixing member for fixing a longitudinal end portion of the sheet-shaped material, wherein tension is adjusted by moving the fixing member along the longitudinal direction. Item 5. An insertion type polarization generator according to Item 4. 6. The insertion type polarization generator according to claim 1, wherein the magnet is an Nd—Fe—B-based rare earth magnet.