JPH097799A - Vacuum vessel for electron accumulating ring - Google Patents

Abstract

PURPOSE: To reduce the discharge gas in the whole body of a vacuum vessel, by generating a specific electromagnetic field in the vacuum vessel, so that a synchrotron radiating light is radiated concentratively to a beam damper where the gas radiation is little. CONSTITUTION: The charged particles 14 are deflected along a specific peripheral track in a vacuum vessel 11 and run by the electromagnetic field formed by a pair of deflection electromagnets 17 provided up and down in the vacuum tub 11, and at the same time, they produces an SOR light 18 in the tangent direction of the peripheral track. This SOR light 18 advances straightly in the vacuum vessel 11, and strikes concentratively to a beam damper 20 fixed and arranged along the inner wall 19 at the side surface of the second space 15. This beam damper 20 is formed of a material with little gas discharge, fixed through an insulating substance, and biased to the positive potential by a bias power source. The optical electrons 23 generated by the SOR light 18 are absorbed there. In such a way, the beam damper 20 can be formed of a material with little gas discharge, regardless of the material of the vacuum vessel 11, and the discharge gas in the whole body of the vacuum vessel 11 can be reduced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a charged particle device, and more particularly to a vacuum container used in an electron storage ring.

[0002]

2. Description of the Related Art Conventionally, in a charged particle device for accelerating or accumulating charged particles, such as an electron storage ring such as a synchrotron, charged particles such as electrons and protons are superposed on a predetermined orbit determined by a deflection electromagnetic field. Orbit at high speed. In order to orbit the charged particles at an ultra-high speed for a long time, the orbit of the charged particles needs to be maintained in an ultravacuum of, for example, 1 × 10 ⁻⁹ Torr or less.

FIG. 3 is a partially cutaway perspective view showing an example of a conventional vacuum chamber. An ion pump 32 is housed in a part of the vacuum chamber 31, and a space 35 in which charged particles 34 circulate is formed through a partition 33 having a large number of through holes. In the side wall of the space 35 opposite to the partition wall 33, a water passage 36 through which cooling water flows and a heater 37 are provided.

[0004]

However, when synchrotron radiation light (hereinafter referred to as SOR light) generated when charged particles orbit the deflection electromagnetic field is applied to the inner wall surface of the vacuum chamber, the synchrotron radiation light is emitted from the synchrotron radiation light. Since a large amount of gas is released, it is difficult to keep the charged particle orbital space in an ultra-vacuum. That is, in the conventional device, the degree of vacuum during the generation of the SOR light was reduced by one digit or more as compared with the time when the SOR light was not generated.

As a countermeasure against such gas emission by SOR light, the following several methods have been tried in the conventional electron storage ring.

First, a material that releases less gas is used as the material of the vacuum chamber. Secondly, the inner surface of the vacuum chamber is subjected to surface treatment such as electrolytic polishing. Thirdly, a large capacity vacuum pump is installed for a large amount of outgassing. Fourth, it utilizes the so-called withering effect, which is to operate the device for several years and wait for the emission gas to decrease.

However, the first method has a drawback that the material forming the vacuum chamber is limited and the second method complicates the manufacturing process. Further, the third method has a drawback that the device becomes large in size, and the fourth method lacks immediateness.

Accordingly, an object of the present invention is to provide a vacuum tank for an electron storage ring which eliminates all the drawbacks of the above conventional method and can reduce the gas emission due to the SOR light with a simple structure.

[0009]

According to the present invention, a vacuum chamber in which charged particles circulate, and a deflection provided outside the vacuum chamber so as to generate a predetermined electromagnetic field in the vacuum layer. Electron storage comprising an electromagnet and a beam damper having a U-shaped cross section provided on the inner wall surface of the vacuum chamber, which is irradiated with synchrotron radiation generated when the charged particles orbit. A vacuum chamber for rings is obtained.

Further, according to the present invention, in the electron storage ring vacuum chamber, the beam damper is fixed to the inner wall surface of the vacuum chamber via an insulator, and the beam damper has a predetermined size with respect to the vacuum chamber. A vacuum chamber device for an electron storage ring, which is characterized in that a bias potential is applied, is obtained.

[0011]

In the above vacuum chamber for the electron storage ring, the synchrotron radiation generated when the charged particles circulate is radiated to the beam damper having a U-shaped cross section provided on the inner wall surface of the vacuum chamber, Gas release is suppressed by the material. Since this beam damper is applied with a predetermined bias potential with respect to the vacuum chamber, this also further suppresses gas release.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vacuum chamber for an electron storage ring according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of the electron storage ring vacuum chamber of the present invention.

The vacuum chamber 11 is composed of a first space 13 for accommodating the vacuum pump 12 at its end and a second space 15 in which charged particles 14 circulate. The first space 13 and the second space 15 are separated by a partition wall 16 having a through hole. The charged particles 14 are deflected along a predetermined orbit in the vacuum chamber 11 by a pair of deflection electromagnets 17, 17 arranged above and below the vacuum chamber 11, and travel at high speed. That is, when the charged particles 14 travel in a direction perpendicular to the paper surface of FIG. 1, the charged particles 14 are circularly deflected by an electromagnetic field directed in the vertical direction parallel to the paper surface, and the tangential direction of the circular orbit (FIG.
SOR light 18 is generated in the direction of arrow). The second space 15 in which the SOR light 18 travels straight in the vacuum chamber 11 and collides with it.
The beam damper 2 with a U-shaped cross section is formed on the inner wall 19 of the side surface of the
0 is fixedly arranged along the inner side wall 19 of the vacuum chamber 11. The beam damper 20 is made of a material that is different from the vacuum chamber 11 and emits little gas, and the length of each side of the U-shaped beam absorbing portion is about 5 mm.

The beam damper 20 is fixed to the inner wall 19 of the vacuum chamber 11 via an insulator 21 as shown in the enlarged view of the main part of FIG. Is biased to a predetermined bias potential, for example, a positive potential. By applying such a bias, the SO emitted to the beam damper 20
The photoelectrons 23 generated by the R light are absorbed by the U-shaped beam absorbing portion 24 of the beam damper 20, and the amount of gas release can be controlled. A pipe 25 for cooling is fixed to the beam damper 20 by soldering or silver brazing.

According to the electron storage ring vacuum chamber of the present invention as described above, the high energy direct light is actually radiated on the rear surface 24-a of the beam absorbing portion 24 to which the SOR light is radiated. It is a portion within 1 mm from the orbital horizontal plane 26. Therefore, the photoelectrons emitted by the irradiation of the SOR light are emitted from the rear surface 24-a in all directions and collide with the upper surface 24-b or the lower surface 24-c of the beam absorbing section 24 having a U-shaped cross section, or It advances into the vacuum chamber 11 from the beam-shaped beam absorbing portion 24. However, the probability that the deflected electromagnets 17, 17 are deflected by the vertical electromagnetic field to collide with the lower surface 24-c of the beam absorbing portion 24 and return to the vacuum chamber 11 is extremely small. This action is further promoted by the bias potential applied to the beam damper 20, as described above. Therefore, according to the present invention, SO
The collision of the photoelectrons 23 caused by the R light is caused by the beam damper 20.
It is limited to the inside of the beam absorbing part 24 having a U-shaped cross section.

[0017]

According to the present invention, since the beam damper irradiated with SOR light can employ a unit structure independent of the vacuum chamber, the characteristics of the beam damper as a structural material of the vacuum chamber must be taken into consideration. However, the selection can be limited to only the performance in which gas emission due to SOR light is small.

Further, according to the present invention, the beam damper which emits less gas is intensively irradiated with the SOR light, and as a result, the gas emitted from the entire vacuum chamber is reduced.

Further, the number of collisions of photoelectrons in the beam damper section is remarkably increased as compared with the conventional vacuum chamber, so that the effect of reducing the gas release amount with time (dead effect) can be promoted.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of a vacuum tank for an electron storage ring according to the present invention.

FIG. 2 is an enlarged view of a main part showing the configuration of a vacuum tank for an electron storage ring according to the present invention.

FIG. 3 is a partially cutaway perspective view showing the configuration of a conventional vacuum tank for an electron storage ring.

[Explanation of symbols]

 11 Vacuum Tank 12 Vacuum Pump 13 First Space 14 Charged Particles 15 Second Space 16 Partition Wall 17 Deflection Magnet 18 SOR Light 20 Beam Damper 21 Insulator 22 Bias Power Supply 23 Photoelectron 24 Beam Absorption Part 25 Piping 26 Orbital Horizontal Plane

Claims (2)

[Claims] 1. A vacuum chamber in which charged particles circulate inside, a deflection electromagnet provided outside the vacuum chamber so as to generate a predetermined electromagnetic field in the vacuum layer, and when the charged particles circulate. A vacuum chamber for an electron storage ring, comprising: a beam damper having a U-shaped cross section, which is provided on an inner wall surface of the vacuum chamber to which the synchrotron radiation generated in the above is irradiated. 2. The vacuum chamber for an electron storage ring according to claim 1, wherein the beam damper is fixed to an inner wall surface of the vacuum chamber via an insulator, and a predetermined bias potential is applied to the vacuum chamber. A vacuum tank for an electron storage ring, which is provided.