JPH0737700A - Synchrotron radiation mirror - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent the radiation mirror from warping or distorting due to thermal expansion. [Structure] A groove 21 for absorbing thermal expansion in the surface layer portion is formed in a reflecting surface 20a that reflects reflected light, and the thermal expansion amount in the surface layer portion is equal to the thermal expansion amount in the back surface side. Close.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchrotron radiation mirror provided in a beam line of a particle accelerator.

[0002]

2. Description of the Related Art In recent years, SOR light (synchrotron radiation light) emitted from a particle accelerator such as a synchrotron is taken out and used as a light source, for example, in the manufacture of VLSI, diagnosis in the medical field, molecular analysis, structural analysis, etc. There is momentum to use it in various fields, and facilities for it are being developed.

FIG. 4 shows an outline of a small synchrotron for utilizing SOR light. In this synchrotron, electrons generated by an electron generator 1 such as an electron gun are accelerated by a linear accelerator (linac) 2 to near the speed of light, deflected by a deflection electromagnet 3, and accumulated by an incident path 4 through an inflector 5. It is incident on the ring 6. The electrons that have entered the storage ring 6 are converged by the converging electromagnet 8 while being given energy by the high-frequency acceleration cavity 7, are deflected by the deflection electromagnet 9, and continue to orbit the storage ring 6. Then, when deflected by the deflecting electromagnet 9, SOR light is emitted in the tangential direction thereof, and the SOR light is emitted to, for example, the exposure device 11 via the beam line 10 which is a light extraction line for use.

The beam line 10 is provided with a radiation mirror 12 as shown in FIG. 5, which is a mirror for condensing SOR light extracted through the beam line 10 and cutting unnecessary SOR light. There is. A plane mirror or a curved mirror is used as the synchrotron radiation mirror 12, silicon is used as a base material, and a reflecting surface 12a made of silicon carbide is used on the surface thereof.
What has formed is generally adopted. Symbol S in FIG.
The portion indicated by indicates the irradiation range of SOR light.

[0005]

By the way, since the SOR light extracted through the beam line 10 has large thermal energy, the synchrotron radiation mirror 1 as described above is used.
2 is irradiated with SOR light, the emission mirror 12 emits SO
It receives the heat energy of the R light and rises in temperature, causing thermal expansion. In this case, the temperature of the surface layer portion of the reflecting surface 12a, which is directly irradiated with the SOR light, greatly rises, but the temperature of the back surface side of the radiation light mirror 12 does not rise as much as that of the front surface side. The front surface side of the reflective surface 1 has a larger thermal expansion than the back surface side and is warped as shown in FIG.
2a may be distorted. Then, when such warpage or distortion occurs, the reflection direction is changed, or the wavelength of the SOR light to be reflected is shifted, so that an effective improvement measure capable of preventing such a situation is demanded. Was there.

[0006]

In view of the above circumstances, the present invention relates to a synchrotron radiation mirror that is provided in a beam line of a particle accelerator and reflects radiant light extracted through the beam line. The reflective surface is formed with a groove for absorbing the deformation of the surface layer of the reflective surface when the surface layer is thermally expanded.

[0007]

By forming the groove on the reflecting surface, the thermal expansion generated in the surface layer portion of the reflecting surface is absorbed by the groove, and the deformation of the entire reflecting surface due to the thermal expansion is reduced. Therefore, by setting the dimensions of the groove in consideration of the difference between the amount of thermal expansion on the reflection surface and the amount of thermal expansion on the back surface, the difference in the amount of thermal expansion between the two is eliminated, which causes warpage and distortion. Prevent.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The synchrotron radiation mirror 20 of the present embodiment is provided in the beam line 10 of the synchrotron for reflecting SOR light, similarly to the conventional one described above, and its shape and dimensions are basically shown in FIG. Although it is the same as the conventional synchrotron radiation mirror 12 shown in FIG. 2, the synchrotron radiation mirror 20 of the present embodiment is different from the conventional one.
The groove 21 for absorbing the thermal expansion is formed in.

That is, on the reflecting surface 20a of the radiation mirror 20 of this embodiment, the irradiation range S of the SOR light to be reflected is S.
A total of four grooves 21 ... Are formed vertically and horizontally, two at each side edge and both ends. The size, the number, the position, etc. of the grooves 21 are determined in consideration of the size of each part of the radiation mirror 20, the coefficient of thermal expansion of the material, the degree of temperature rise when SOR light is irradiated, and the like.
It is determined so as to prevent the thermal expansion amount at 0a from becoming larger than the thermal expansion amount at the back surface side.

Specifically, for example, the total value of the width dimensions of the two grooves 21 formed along the length direction is the thermal expansion amount in the width direction in the surface layer portion of the reflecting surface 20a and the width in the back surface side. Set to be equal to or larger than the difference in the amount of thermal expansion in the direction. That is, a part of the surface layer portion that expands more than the back surface side is cut off in advance as the groove 21 by at least the amount corresponding to the difference in the thermal expansion amount, whereby the thermal expansion amount in the surface layer portion and the back surface portion are reduced. The difference with the amount of thermal expansion on the side is eliminated. The width dimensions of the two grooves 21 formed along the width direction are also set in the same manner. Further, the depth dimension of each groove 21 is set within a range from the surface of the reflecting surface 20a to a position where the temperature rise is particularly remarkable.

By providing the groove 21 as described above,
When the reflecting surface 20a rises in temperature and thermally expands, the groove 21 is deformed so as to be crushed as shown in FIG. 3, whereby the thermal expansion in the surface layer portion of the reflecting surface 20a is absorbed. Then, by setting the dimensions of the groove 21 as described above, the thermal expansion amount of the entire reflecting surface 20a can be made approximately the same as the back surface side, and as a result, the difference in the thermal expansion amount between the surface layer portion and the back surface side can be reduced. It is possible to prevent the occurrence of warpage or distortion caused by it, to keep the reflection surface 20a always flat, and to prevent the reflection direction from changing or the wavelength of the SOR light to be reflected from shifting. obtain.

[0012]

As described above, the synchrotron radiation mirror of the present invention has a groove formed on the reflecting surface for absorbing thermal expansion of its surface layer, and therefore, when radiated by radiant light. It is possible to equalize the surface layer portion where the temperature greatly rises and the thermal expansion amount on the back surface side where the temperature does not rise so much, and therefore warpage and strain caused by the difference in the thermal expansion amount can be prevented. It has an excellent effect that it can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a perspective view showing a synchrotron radiation mirror that is an embodiment of the present invention.

FIG. 2 is a sectional view of the synchrotron radiation mirror.

FIG. 3 is a cross-sectional view showing a state where the radiation mirror is thermally expanded.

FIG. 4 is a plan view showing an outline of a small synchrotron.

FIG. 5 is a perspective view showing a conventional general synchrotron radiation mirror provided in a beam line of the synchrotron.

FIG. 6 is a cross-sectional view showing a state in which the radiation mirror is thermally expanded and warped.

[Explanation of symbols]

 10 Beamline 20 Synchrotron Mirror 20a Reflective Surface 21 Groove.

Claims (1)

[Claims] 1. A synchrotron radiation mirror provided on a beamline of a particle accelerator for reflecting radiant light extracted through the beamline, wherein a reflecting surface for reflecting the radiant light has a surface layer portion which is a heat source. A synchrotron radiation mirror for a particle accelerator, characterized in that a groove is formed to absorb the deformation when expanded.