JP4031798B2 - Vacuum chamber of charged particle accelerator - Google Patents

Description

  The present invention relates to a vacuum chamber of a charged particle accelerator that accelerates charged particles such as electrons, positrons, and ions to a high energy state.

  Charged particle accelerators are charged particles by accelerating the charged particles such as electrons, positrons, and ions in a linear or annular vacuum chamber with an ultra-high vacuum inside by a magnetic field and accelerating to near the speed of light by an electric field. It is a device that imparts high energy.

  In such a charged particle accelerator, when high-energy charged particles close to the speed of light pass through the magnetic field and the orbit bends, radiated light is generated in the tangential direction of the charged particle's orbit, and this radiated light is emitted from the vacuum chamber. Irradiate the radially inner wall surface. As a result, the inner wall surface is overheated and not only a great heat load is applied to the vacuum chamber, but also a photoelectron is emitted from the inner wall surface due to the photoelectric effect associated with the irradiation of the radiated light, which becomes an obstacle to the surrounding charged particles. There was a problem.

  For this reason, an ante portion is formed on the outer side in the radial direction of the vacuum chamber of the circular channel beam channel around which the charged particles of the vacuum chamber circulate so as to be separated from the orbit of the charged particles (around the axis of the beam channel), Various types of cooling channels are provided in which cooling water is circulated so as to be adjacent to the radially inner wall surface of the vacuum chamber irradiated with the radiation light of the antenna portion.

  With such a configuration, the distance from the orbit of the charged particle to the inner wall surface of the antenna portion is increased, and accordingly, the distance between the photoelectrons emitted from the inner wall surface and the surrounding charged particle is also increased. As a result, the thermal load applied to the vacuum chamber with the irradiation of the radiated light is suppressed, and the circular orbit of the charged particles on which the photoelectrons emitted with the irradiation of the radiated light travel cannot be easily reached.

  The vacuum chamber of the conventional charged particle accelerator described above is disclosed in Non-Patent Document 1, for example.

Y.Suetsugu, 11 others, “R & D OF COPPER BEAM DUCT WITH ANTECHAMBER SCHEME FOR CURRENT ACCELERATORS”, Internet <http://www-lib.kek.jp/cgi-bin/kiss prepri? KN = 200427053 & 0F = 8.>

  However, in the conventional charged particle accelerator vacuum chamber, a groove-shaped (U-shaped) pump channel is joined to form a pump chamber for evacuating the chamber body, and this pump channel is drawn. Therefore, the ratio of machining is increased, leading to an increase in manufacturing cost.

  Further, in charged particle acceleration in recent years, the energy of charged particles has been further increased, and the heat load applied to the vacuum chamber due to the irradiation of radiation is increased accordingly. If the vacuum chamber is held at a high temperature, not only will the degree of vacuum be reduced, but the material may extend and the vacuum chamber may be thermally deformed. For this reason, although the heat resistance of a vacuum chamber, ie, the improvement of cooling performance, is calculated | required, in the vacuum chamber of the conventional charged particle accelerator, cooling performance was not enough. As described above, some vacuum chambers with insufficient cooling performance are provided with a new cooling channel on the outer peripheral surface of the beam channel, but the structure becomes complicated and the machining ratio increases. This led to an increase in manufacturing costs.

  Therefore, the present invention solves the above-mentioned problem, and a charged particle accelerator capable of reducing the machining ratio and reducing the manufacturing cost with a simple configuration and having high cooling performance. An object is to provide a vacuum chamber.

The vacuum chamber of the charged particle accelerator according to the first invention for solving the above-described problem is
A beam channel that circulates charged particles;
Ante portion that communicates with the beam channel on the outside thereof, and through which the radiated light radiated in the tangential direction with the circulation of the charged particles passes ,
Photoelectrons generated when the inner wall is irradiated with the radiated light passing through the ante portion and extending to be substantially perpendicular to the radiation direction of the radiated light and communicating with the ante portion on the outside thereof. A pocket to stay inside ,
A cooling channel for circulating cooling water between the outer surface of the pocket portion , and
A pump plate that is formed in a plate shape and forms a pump chamber that houses a pump for evacuating the beam channel, the antenna portion, and the outer surface of the pocket portion ;
One end of the pump plate is joined to the beam channel, and the other end of the pump plate is joined to the pocket portion.

The vacuum chamber of the charged particle accelerator according to the second invention for solving the above-mentioned problems is as follows.
In the vacuum chamber of the charged particle accelerator according to the first invention,
One end of the pump plate is joined to a mounting seat formed on the beam channel, and the other end of the pump plate is joined to a mounting seat formed on the pocket portion.

A vacuum chamber of a charged particle accelerator according to a third invention for solving the above-described problem is
In the vacuum chamber of the charged particle accelerator according to the first or second invention,
The cooling channel is formed in a groove shape having an opening on the inside, and is joined so that the opening of the cooling channel is fitted into a step formed in the pocket.

A vacuum chamber of a charged particle accelerator according to a fourth invention for solving the above-described problem is
In the vacuum chamber of the charged particle accelerator according to any one of the first to third inventions,
The beam channel, the antenna portion, the pocket portion, the cooling channel, and the pump plate are made of oxygen-free copper.

According to the vacuum chamber of the charged particle accelerator according to the first aspect of the invention, the beam channel for circulating the charged particles, the beam channel communicated with the outside of the beam channel, and the emitted light radiated in the tangential direction as the charged particles circulate The ante part through which the antenna passes and the antenna part communicate with the outside of the ante part and extend so as to be substantially orthogonal to the radiation direction of the emitted light, and the inner wall is irradiated with the emitted light that has passed through the ante part. A pocket portion that retains photoelectrons generated when the inside, a cooling channel that circulates cooling water between the outer surface of the pocket portion, a plate-like shape, the beam channel, the antenna portion, and the pocket keep between the outer parts and a pump plate which forms a pump chamber for housing the pump to these vacuum, one end of said pump plate By joining the beam channel and the other end of the pump plate to the pocket portion, the vacuum chamber has a simple configuration, the ratio of machining such as drawing is reduced, and the manufacturing cost is reduced. And can have high cooling performance.

  According to the vacuum chamber of the charged particle accelerator according to the second invention, in the vacuum chamber of the charged particle accelerator according to the first invention, one end of the pump plate is joined to the mounting seat formed in the beam channel, Since both ends of the pump plate are fixed by joining the other end of the pump plate to a mounting seat formed in the pocket portion, workability at the time of joining can be improved.

According to the vacuum chamber of the charged particle accelerator according to the third invention, in the vacuum chamber of the charged particle accelerator according to the first or second invention, the cooling channel is formed in a groove shape having an opening inside, and the pocket The cooling channel can be easily joined by joining so as to fit the opening of the cooling channel into the step formed in the part.

  According to the vacuum chamber of the charged particle accelerator according to the fourth invention, in the vacuum chamber of the charged particle accelerator according to any one of the first to third inventions, the beam channel, the antenna portion, the pocket portion, and the cooling channel. In addition, by forming the pump plate with oxygen-free copper, the thermal conductivity is improved, and a sufficient cooling effect can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view of a charged particle accelerator including a vacuum chamber according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. The arrows shown in FIG. 2 indicate the vertical direction and radial direction of the charged particle accelerator 1 and the vacuum chamber 3.

  As shown in FIG. 1, the charged particle accelerator 1 is configured in a ring shape as a whole by connecting a large number of linear vacuum chambers 2 and arcuate vacuum chambers 3. Between the vacuum chamber 2 and the adjacent vacuum chamber 3, a bellows 4 conforming to a cross section of the vacuum chamber 2 described later is interposed, and between the vacuum chamber 3 and another adjacent vacuum chamber 3. Is provided with a bellows 5 adapted to a transverse section of a vacuum chamber 3 to be described later. That is, flanges 2a and 3a are provided at both ends of vacuum chambers 2 and 3, while flanges 4a and 5a are provided at both ends of bellows 4 and 5, and vacuum chambers 2 and 3 are connected to flanges 2a and 3a and bellows 4 respectively. , 5 are connected by being joined to the flanges 4a, 5a. By being configured in this way, the charged particle accelerator 1 circulates charged particles such as electrons, positrons, ions, etc. by a magnetic field in the vacuum chambers 2 and 3 having an ultrahigh vacuum inside, and accelerates them to near the speed of light. High energy can be imparted to the charged particles.

  Here, by applying a periodic magnetic field along the trajectory of the charged particles to the vacuum chamber 2, the charged particles are deflected and meandered, and thereby a wiggler called an insertion light source for taking out light of a specific wavelength. (Not shown) is provided. The wiggler is provided along the longitudinal direction of the vacuum chamber 2 on the top and bottom of the vacuum chamber 2 (in the direction of the arrow shown in FIG. 2). The magnet is configured to generate a magnetic flux that vertically penetrates the vacuum chamber 2 and reverses its direction alternately. Therefore, in the vacuum chamber 2 equipped with a wiggler, a periodic magnetic field is applied to the charged particles passing therethrough, that is, in a direction perpendicular to the magnetic flux, that is, in the horizontal direction (the radial direction of the charged particle accelerator 1: the arrow direction shown in FIG. 2). The charged particles meander, and radiant light is emitted in the tangential direction during the meandering.

  On the other hand, the wiggler as described above is not provided in the vacuum chamber 3, and therefore, charged particles circulate along the axial direction of the vacuum chamber 3 in the vacuum chamber 3. Radiated light is emitted in the tangential direction.

  That is, in the charged particle accelerator 1, the radiated light is radiated to the inner wall surfaces inside and outside in the radial direction of the charged particle accelerator 1 in the vacuum chamber 2, and the charged particle accelerator 1 (vacuum chamber 1) in the vacuum chamber 3. Radiation light is radiated to the radially inner wall surface of 3).

  Next, the configuration of the vacuum chamber 3 will be described with reference to FIG.

  As shown in FIG. 2, the vacuum chamber 3 includes a chamber body 11, a cooling channel 12, and NEG plates 13 and 14 that extend in the axial direction of the vacuum chamber 3 and are formed of oxygen-free copper.

  The chamber body 11 is formed by integrally forming the beam channel 15, the antenna portion 16 and the pocket portion 17. The cross section of the beam channel 15 is formed in a substantially circular shape, and the periphery of the axis is a circular orbit of charged particles. The ante portion 16 extends in the radiation direction (radial direction of the charged particle accelerator 1 or radial direction of the vacuum chamber 3) of the radiated light radiated in the tangential direction as the charged particles circulate, and has a rectangular cross section. Is formed. The pocket portion 17 is provided outside the antenna portion 16 and extends in a substantially vertical direction with respect to the radiation direction of the emitted light.

  Further, mounting seats 18 and 19 are formed in the beam channel 15, and exhaust slits 20 and 21 are opened in the antenna portion 16. And the mounting seats 22 and 23 are formed inside the pocket part 17, and the step part 24 is formed outside.

  The cooling channel 12 is formed in a groove shape (U shape) in cross section, and is joined to a step portion 24 formed in the pocket portion 17 so as to fit the opening of the cooling channel 12. Thereby, the cooling water channel 25 is formed by the outer surface of the pocket portion 17 and the inner surface of the cooling channel 12.

  The NEG plates 13 and 14 are formed in a plate shape, and one end thereof is joined to the mounting seats 18 and 19 of the beam channel 15, and the other end is joined to the mounting seats 22 and 23 of the pocket portion 17. Thus, pump chambers 26 and 27 are formed by the chamber body 11 and the NEG plates 13 and 14. The pump chambers 26 and 27 are provided with NEG (Non Evaporable Getter) pumps 28 on the exhaust slits 20 and 21.

  That is, by driving the NEG pump 28, the inside of the beam channel 15, the antenna portion 16 and the pocket portion 17 are brought into an ultrahigh vacuum, and when charged particles circulate around the axis of the beam channel 15, Synchrotron radiation is emitted in the tangential direction as it goes around. The radiated light passes through the antenna portion 16 and then irradiates the inner wall surface outside the pocket portion 17. At this time, the inner wall surface is heated, but is cooled by the cooling water flowing in the cooling water passage 25.

  Accordingly, by forming the NEG plates 13 and 14 in a plate shape by the above-described configuration, the drawing process can be easily performed, or the plate material can be used as it is. Further, by joining one end of the NEG plates 13 and 14 to the mounting seats 18 and 19 of the beam channel 15 and joining the other end to the mounting seats 22 and 23 of the pocket portion 17, it is easy to join the chamber body 11. Work efficiency can be improved. Further, when the pocket portion 17 is formed outside the antenna portion 16 so as to extend in a direction substantially perpendicular to the radiation direction of the radiated light, when the radiated light irradiates the inner wall surface outside the pocket portion 17. The generated photoelectrons can be retained in the pocket portion 17, and the charged particles circulating around the axis of the beam channel 15 are not adversely affected. Further, the cooling channel 12 can be easily joined by being joined so as to be fitted into the stepped portion 24 of the pocket portion 17.

  And since the pocket part 17 is extended in the substantially perpendicular | vertical direction with respect to the radiation direction of radiated light, the contact length with the cooling water channel 25 can be lengthened, and the chamber main body 11 can be cooled efficiently. it can. Thereby, it is only necessary to provide the cooling channel 12, and it is not necessary to newly provide a cooling channel in the beam channel as in the conventional vacuum chamber, and the configuration of the vacuum chamber 3 can be simplified. Further, by forming the chamber main body 11, the cooling channel 12, and the NEG angles 13, 14 with oxygen-free copper, the thermal conductivity is improved and a sufficient cooling effect can be obtained.

  Note that the above-described configuration and joining method of the vacuum chamber 3 can also be applied to the vacuum chamber 2 having the antenna portions on both sides of the beam channel, like a conventional vacuum chamber having a wiggler.

Therefore, according to the vacuum chamber of the charged particle accelerator of the present invention, the beam channel 15 that circulates the charged particles, the beam channel 15 communicates with the outside of the beam channel, and the radiated light radiated in the tangential direction as the charged particles circulate. The ante part 16 through which the antenna passes, and the antenna part 16 communicate with the outside thereof and extend so as to be substantially orthogonal to the radiation direction of the radiated light, and the radiated light that has passed through the ante part 16 has its inner wall Are formed in the shape of a plate , a cooling channel 12 for circulating cooling water between the outer surface of the pocket 17 and the beam channel 15 and the antenna 16. and NEG play to form a pump chamber 26, 27 for accommodating the NEG pump 28 for them to vacuum keep between the outer surface of the pocket portion 17 13 and 14, one end of the NEG plates 13, 14 is joined to the beam channel 15, and the other end of the NEG plates 13, 14 is joined to the pocket portion 17, whereby the vacuum chamber 3 has a simple configuration. The ratio of machining (drawing) of the NEG plates 13 and 14 is reduced, and the manufacturing cost can be reduced. And since the contact area of the cooling water channel 25 is expanded, it can have high cooling performance.

  Further, one end of the NEG plates 13 and 14 is joined to mounting seats 18 and 19 formed on the beam channel 15, while the other end of the NEG plates 13 and 14 is joined to mounting seats 23 and 24 formed on the pocket portion 17. By doing so, both ends of the NEG plates 13 and 14 are fixed, so that workability at the time of joining the NEG plates 13 and 14 can be improved.

In addition, the cooling channel 12 can be easily formed by forming the cooling channel 12 into a groove shape having an opening on the inside and joining the step 24 formed in the pocket portion 17 so that the opening of the cooling channel 12 is fitted. Can be joined.

  Furthermore, by forming the chamber body 11, the cooling channel 12, and the NEG angles 13 and 14 with oxygen-free copper, the thermal conductivity is improved, and a sufficient cooling effect can be obtained.

  The present invention can be applied to a charged particle accelerator that circulates and accelerates charged particles.

It is a top view of the charged particle accelerator provided with the vacuum chamber which concerns on one Example of this invention. It is AA arrow sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charged particle accelerator 2, 3 Vacuum chamber 2a, 3a Flange 4, 5 Bellows 4a, 5a Flange 11 Chamber main body 12 Cooling channel 13, 14 NEG plate 15 Beam channel 16 Ante part 17 Pocket part 18, 19, 22, 23 Mounting seat 20, 21 Exhaust slit 24 Step 25 Cooling channel 26, 27 Pump chamber 28 NEG pump

Claims (4)

A beam channel that circulates charged particles;
Ante portion that communicates with the beam channel on the outside thereof, and through which the radiated light radiated in the tangential direction with the circulation of the charged particles passes ,
Photoelectrons generated when the inner wall is irradiated with the radiated light passing through the ante portion and extending to be substantially perpendicular to the radiation direction of the radiated light and communicating with the ante portion on the outside thereof. A pocket to stay inside ,
A cooling channel for circulating cooling water between the outer surface of the pocket portion , and
A pump plate that is formed in a plate shape and forms a pump chamber that houses a pump for evacuating the beam channel, the antenna portion, and the outer surface of the pocket portion ;
One end of the pump plate is joined to the beam channel, and the other end of the pump plate is joined to the pocket portion. A vacuum chamber for a charged particle accelerator, wherein: In the vacuum chamber of the charged particle accelerator according to claim 1,
One end of the pump plate is joined to a mounting seat formed in the beam channel, and the other end of the pump plate is joined to a mounting seat formed in the pocket portion. . In the vacuum chamber of the charged particle accelerator according to claim 1 or 2,
A vacuum for a charged particle accelerator, wherein the cooling channel is formed in a groove shape having an opening on the inside, and is joined so as to fit the opening of the cooling channel into a step formed in the pocket. Chamber. In the vacuum chamber of the charged particle accelerator according to any one of claims 1 to 3,
The beam channel, the antenna portion, the pocket portion, the cooling channel , and the pump plate are made of oxygen-free copper.

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