JPH0676996A - Deflection chamber in particle accelerator - Google Patents

Abstract

(57) [Summary] [Structure] Orbital portion 20a in the shape of an arc around which charged particles orbit.
And a take-out portion 20b for radiating light radiated tangentially outward from the track portion are integrally formed, and the front wall surface 2 of the take-out portion is formed.
Beam line 9 is connected to 0c. Then, in a portion near the front wall surface, an extraction chamber 22 is provided, which is separated from other portions by a thin film 21 of beryllium or the like that allows transmission of radiated light. [Effect] The emitted light passes through the thin film, enters the extraction chamber, passes through the inside thereof, and is extracted without any trouble. Then, the gas released from the front wall is blocked by the thin film and stays in the extraction chamber, so that it does not diffuse to the orbital part of the charged particles, thus preventing the life of the charged particles from being shortened. it can.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection chamber in a particle accelerator such as a synchrotron.

[0002]

2. Description of the Related Art In recent years, a synchrotron is being developed as a relatively small particle accelerator having a diameter of 10 m or less,
By using synchrotron radiation (SOR light) which is radiation emitted from such synchrotron, for example, various fields such as manufacturing of VLSI circuits, diagnosis in the medical field, molecular analysis, structural analysis, etc. Expected to be applied.

FIG. 3 shows an outline of the synchrotron. In this synchrotron, an electron beam generated by an electron generator 1 such as an electron gun is accelerated by a linear accelerator (linac) 2 to near the speed of light, deflected by a deflecting electromagnet 3 and then stored in a storage ring 5 via an inflector 4. Incident. The electron beam incident on the storage ring 5 is converged by the converging electromagnets 7 ... While being given energy by the high-frequency acceleration cavity 6 and is deflected by the deflection electromagnets 8 ... Then, when the SOR light is deflected by the deflection electromagnet 8, the SOR light is emitted and emitted to, for example, the exposure device 10 via the beam line 9 which is a light extraction line for use.

A deflection chamber 11 (see FIG. 4) for taking out SOR light emitted from the deflection portion of the synchrotron, that is, the arc-shaped portion of the storage ring 5 provided with the deflection electromagnet 8 is provided. Has been.
The deflection chamber 11 is an arc-shaped orbit portion 11a in which the electron beam orbits and becomes a part of the storage ring 5, and an extraction portion for guiding the SOR light radiated outward from the orbit portion 11a to the beam line 9. 11b and the beam line 9 (three in the illustrated example) via the extraction port 12 on the front wall surface 11c of the extraction portion 11b.
Are connected. The internal space of the deflection chamber 11 is maintained in an ultrahigh vacuum equivalent to that in the storage ring 5.

[0005]

By the way, in the above-mentioned conventional deflection chamber 11, as shown in FIG. 4, the front wall surface 11c, which is the mounting surface of the beam line 9, has an SO.
It is inevitable that part of the R light will be emitted,
Gas is released not only from the surface layer portion but also from the deep portion from the portion irradiated with the SOR light by the so-called photodegassing action and thermal excitation action. The gas released therefrom may diffuse not only to the extraction portion 11b but also to the orbit portion 11a. In that case, the electron beam circulating around the orbit portion 11a collides with the emitted gas. The problem that the beam life is shortened remarkably occurs, and it has been demanded to provide effective improvement measures.

[0006]

SUMMARY OF THE INVENTION The present invention is a deflection chamber provided in a deflecting portion for charged particles in a particle accelerator such as a synchrotron and for extracting radiation emitted from the deflecting portion to a beam line. , An arc-shaped orbital portion in which charged particles circulate in a continuous manner with a storage ring, and an extraction portion for radiated light emitted tangentially outward from the orbital portion are integrally formed, and the front wall surface of the extraction portion is A beam line is connected, and an extraction chamber, which is partitioned from other portions by a thin film of beryllium or the like that allows transmission of radiated light, is provided in a portion near the front wall surface in the extraction portion. It is a thing.

[0007]

In the deflection chamber of the present invention, the charged particles are deflected as they pass through the arcuate orbital portion, and the emitted light is emitted tangentially outside the orbital portion, and the emitted light is emitted from the orbital portion to the extraction portion. The light is emitted, penetrates the thin film, enters the extraction chamber, passes through the inside thereof, and is extracted from the beam line. that time,
Part of the synchrotron radiation is irradiated to the front wall of the extraction chamber, and gas is released from it, but the released gas is blocked by the thin film and remains in the extraction chamber, where it may diffuse to the orbit. Absent.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 is a plan view of a deflection chamber that is an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II--II in FIG.

The deflection chamber 20 of this embodiment, like the conventional one, has an arc-shaped orbit portion 20a in which an electron beam (charged particles) circulates in series with the storage ring 5, and a tangentially outer side from the orbit portion 20a. Is formed integrally with the extraction portion 20b of the SOR light emitted to the
The three beam lines 9 are connected to the front wall surface 20c of the vehicle through the take-out port 12, and a portion near the front wall surface 20c is separated from the other portion by the thin film 21. A chamber 22 is provided. Take-out room 22
A beryllium thin film having a thickness of about several μm that allows the transmission of SOR light is used as the thin film 21 partitioning the thin film 21, and the thin film 21 is supported at its peripheral edge by the frame 23 as shown in FIG. Therefore, it is attached inside the take-out portion 20b.

Further, the exhaust port 2 is provided on the bottom of the take-out chamber 22.
4 is provided, and the inside of the extraction chamber 22 is maintained at a vacuum by evacuation via an exhaust port 24 by an exhaust device (not shown). However, the degree of vacuum is different from that of the deflection chamber 20. It is not necessary to make an ultra-high vacuum like the part of (1), the released gas from the front wall surface 20c can be quickly exhausted as described later, and the thin film 21 is not destroyed by the differential pressure generated on both sides thereof. It should be set to a degree.

A water cooling jacket 25, through which cooling water flows, is provided outside the front wall surface 20c.
The front wall surface 20c has a water-cooled double wall structure. Further, a water-cooling jacket 26 is provided on the wall surface of the chamber 20 outside the mounting position of the thin film 21 over the entire circumference. The thin film 21 is cooled via the wall surface and the frame 23.

In the deflection chamber 20 having the above structure, the electron beam is deflected when passing through the arc-shaped orbit portion 20a, and the SOR light is radiated tangentially outside the orbit portion 20a. The SOR light is emitted from the orbit portion 20a to the extraction portion 20b, passes through the beryllium thin film 21 and enters the extraction chamber 22, passes through the inside thereof, and is extracted from the beam line 9. At that time, a part of the SOR light is irradiated to the front wall surface 20c of the extraction chamber 22, and gas is released from the surface layer and the deep portion of the front wall surface 20c, but the released gas is blocked by the thin film 21. Since it is captured and stays in the extraction chamber 22 and is exhausted through the exhaust port 24, the released gas does not diffuse to the track portion 20a unlike the conventional case. Therefore, it is possible to prevent the electron beam circulating in the orbit portion 20a from colliding with the emitted gas and scattering, and it is possible to avoid shortening the life of the electron beam.

The front wall surface 20c has a water cooling jacket 25.
Since it has a double wall structure, the front wall surface 20c
There is an advantage that the temperature rise of the front wall surface 20c due to the irradiation of the SOR light is suppressed, and thereby the amount of gas released from the front wall surface 20c itself is reduced.

Further, since the SOR light passes through the thin film 21, gas is also released from the thin film 21, and the thin film 2
Although the temperature of No. 1 also rises, the thickness of the thin film 21 is extremely thin, and the thin film 21 is cooled by the water cooling jacket 26 via the wall surface of the chamber 20 and the frame 23, and the temperature rise is also suppressed. Therefore, the gas is released from the thin film 21 only slightly at the beginning of the operation, and the gas is not released to the extent that the life of the electron beam is adversely affected.

The position and shape of the take-out chamber 22 are changed by changing the installation position of the thin film 21, but at the installation position of the thin film 21, the gas released from the front wall surface 20c is guided to the track portion 20a. Can prevent diffusion and S
The OR light may be arbitrarily changed as long as it can pass the OR light without any trouble.
It is also possible to install the thin film 21 parallel to c or install the thin film 21 along the boundary between the track portion 20a and the take-out portion 20b to make the entire take-out portion 20b as the take-out chamber 22. Needless to say, the material and thickness of the thin film 21 may be set appropriately in consideration of its shape, required strength, and the like.

[0016]

As described above, according to the deflection chamber of the present invention, the portion in the vicinity of the front wall surface to which the beam line is connected is partitioned by a thin film of beryllium or the like which allows transmission of radiated light. Since the extraction chamber is provided, the emitted light can be taken out without any trouble, and the gas emitted by the irradiation of the front wall with the emitted light remains in the extraction chamber and the orbital portion of the charged particles. Therefore, it is possible to prevent the charged particles from diffusing even further, and thus it is possible to prevent the charged particles from colliding with the emitted gas and shortening its life.

[Brief description of drawings]

FIG. 1 is a plan view showing a schematic configuration of a deflection chamber that is an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a diagram showing an outline of a synchrotron.

FIG. 4 is a plan view showing a schematic configuration of a conventional deflection chamber.

[Explanation of symbols]

 5 Storage ring 9 Beam line 20 Deflection chamber 20a Track part 20b Extraction part 20c Front wall surface 21 Thin film 22 Extraction chamber

Claims (1)

[Claims] 1. A deflection chamber provided in a deflecting part of a charged particle in a particle accelerator such as a synchrotron for extracting radiation emitted from the deflecting part to a beam line, the charged particle being connected to a storage ring. A circular arc-shaped orbit part that circulates, and an extraction part of the emitted light radiated tangentially outward from the orbit part are integrally formed, and the beam line is connected to the front wall surface of the extraction part, and A deflection chamber in a particle accelerator, characterized in that, in a portion in the vicinity of the front wall surface in the extraction portion, an extraction chamber is provided which is partitioned from another portion by a thin film of beryllium or the like that allows transmission of radiant light.