JP2001254678A - Cryopump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cryopump 10 to decrease the generation of a radiation heat to chevron baffle 220 and reduce an equipment cost and a maintenance cost mainly through simple constitution. SOLUTION: A cryopump is provided with a chevron baffle 220, an activated carbon panel 240, and a shield container 230 to contain the chevron baffle 220 and the activated carbon panel 240 and comprises a cryopanel 210 incorporated in a vacuum vessel 300, a first refrigerator 260A to cool an activated carbon panel 210, and a second refrigerator 260B to cooled the chevron baffle 220. A shield plate 20 to shield a radiation heat radiated from an inner wall surface 300a of the vacuum vessel 300 is arranged between the chevron baffle 220 and the inner wall surface 300a of the vacuum tank 300, and a small helium refrigerator is used as the second refrigerator 260B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a cryopump mainly used as a vacuum device for an electron storage ring, and to an electron storage ring provided with the cryopump as a vacuum device.

[0002]

2. Description of the Related Art In an electron storage ring, a cryopump has conventionally been used as a vacuum device for maintaining a high vacuum in a beam duct for storing an electron beam in an orbit. Hereinafter, the basic configuration of the electron storage ring will be briefly described, and the configuration and basic operation of the cryopump will be described in detail.

[0003] Electrons (including positrons) moving at high energies, when their orbits are forcibly changed, emit synchrotron radiation (hereinafter, referred to as bremsstrahlung) in the tangential direction.
Called "SR". ) Is released. By utilizing this property, a small electron storage ring intended for use as an SR light source having a desired wavelength and intensity has been put to practical use. The basic principle of the small electron storage ring is described in detail in Japanese Patent Application No. 11-227051, and in this specification, the basic configuration will be simply described with reference to FIG.

FIG. 2 shows an example of a small electron storage ring.
1 shows a plan view of a racetrack type electron storage ring 100. FIG. In this type of electron storage ring 100, as shown in FIG.
B is opposed to the beam duct 130 maintained at a high vacuum.
The septum electromagnet 12
Electrons (hereinafter, also referred to as “electron beams”) incident through a zero are accumulated at a desired energy by a deflecting action of a magnetic field in a circular design orbit in a horizontal plane.

[0005] Further, other main components of the electron storage ring 100 include quadrupole electromagnets 150A and 150B for converging an electron beam in a design trajectory, a high-frequency accelerating cavity 160 for supplying energy to the stored electron beam, and an electron. Electromagnet 17 that forms an incident trajectory at the time of incidence
0, a beam position monitor 180 for monitoring whether or not the electron beam is accumulated as designed on the circuit design orbit in the beam duct 130.

The electron storage ring 100 shown in FIG. 2 is a typical electron accelerator developed mainly as a light source for SR. The current of the electron beam to be stored is large, the radius of curvature of the bending electromagnet is reduced in a strong magnetic field, and the critical wavelength of SR is shortened to the relatively high energy X-ray region. In particular, used as a small light source for X-ray lithography It is intended to be.

Next, referring to FIG. 3 and FIG. 2, a cryopump 20 which is a vacuum device of the electron storage ring 100 will be described.
0 will be described. FIG. 3 shows a conventional cryopump 200 used as a vacuum device for the electron storage ring 100.
It is a longitudinal side view which shows schematic structure of.

The bending electromagnets 110A and 110B shown in FIG.
In the section, as shown in FIG. 3, the beam duct 130 has a gap G formed on the radiation side of the SR in order to utilize the SR radiated when deflected. Therefore, in order to prevent the vacuum from breaking from the gap G, the beam duct 130 itself is housed in the vacuum chamber 300. In the beam duct 130, electrons orbit around the orbit at almost the speed of light. Therefore, in order to prevent a situation in which electrons are lost due to interaction with ions or the like, it is necessary to maintain a high vacuum state. There is. By keeping the vacuum chamber 300 at a high vacuum, the inside of the beam duct 130 can be made a high vacuum.

A cryopump 200 is used as a vacuum device for maintaining a high vacuum in the vacuum chamber 300. The basic configuration of the cryopump 200 will be described with reference to FIG.

The main components of the cryopump are a cryopanel 210, a small helium refrigerator 260 serving as a first refrigerator, and a liquid nitrogen refrigerator 280 serving as a second refrigerator.
It is. The cryopanel 210 is, as shown in FIG.
A chevron baffle 220 serving as a gas suction port,
It has a box-shaped shield container 230 for blocking radiant heat from the inner wall surface 300a of the vacuum chamber 300, and an activated carbon panel 240 supported and attached to the inside of the container 230 by a heat insulating material. It is.

In the conventional cryopump 200, the activated carbon panel 240 is cooled to an absolute temperature of 4 to 10K by a small helium refrigerator 260 as a first refrigerator using helium gas circulating in a cooling pipe 262 as a refrigerant. I have. The chevron baffle 220 is cooled by a liquid nitrogen type refrigerator 280 as a second refrigerator.
Liquid nitrogen circulating as a refrigerant, the absolute temperature of 80 to 90
Cooled to about K.

The function of the cryopump 200 as a vacuum device is such that moisture is adsorbed by the chevron baffle 220 and the shield container 230, and other gases are passed through the chevron baffle 220 and adsorbed by the activated carbon panel 240 to act. ing.

In order to maintain the gas adsorption efficiency of the activated carbon panel 240, it is necessary to keep the temperature of the activated carbon panel 240 low. However, the reflected light of SR emitted from the gap G exists inside the vacuum chamber 300, and there is a problem of radiant heat from the inner wall surface 300a of the vacuum chamber 300 at room temperature. On the other hand, the cooling capacity of the small helium refrigerator 260 is not so large, and it is necessary to shield the activated carbon panel 240 therefrom.

As shown in FIG. 3, in the conventional cryopump 200, an activated carbon panel 240 is housed in a box-shaped shield container 230 via a heat insulating material, and shields radiant heat and reflection SR from above and from the side. Below, a chevron baffle 220 is arranged to prevent radiant heat and reflection SR.

Accordingly, the chevron baffle 220 has a structure in which a black chrome plating is applied to an aluminum material, the cross section is formed in a substantially "C" shape as shown in FIG. 3, and a large number of baffle plates 222 for passing gas are arranged. ing. Accordingly, the chevron baffle 220 absorbs the reflected light of the SR from below and the radiant heat from the inner wall surface 300a of the vacuum chamber 300, and can always cool the activated carbon panel 240 to a very low temperature level, thereby maintaining the adsorption capacity. it can.

Accordingly, as described above, since the surface of the chevron baffle 220 is made black and absorbs SR and radiant heat, the second refrigerator for cooling the chevron baffle 220 is provided with a liquid nitrogen type having a large cooling capacity. A refrigerator 280 is used. In addition, the shielding container 230 is also particularly,
Liquid nitrogen type refrigerator 2 because there is no need to cool to extremely low temperatures
Cooled at 80.

FIG. 3 shows the first and second refrigerators.
A supplementary explanation will be given using. First, a small helium refrigerator 2
As shown in FIG. 3, reference numeral 60 denotes a configuration in which the helium gas is cooled by the refrigerator main body 264 and the helium gas is circulated through the cooling pipe 262. As described above, the first cooling the activated carbon panel 240 is performed. It is used as a refrigerator and has a small cooling capacity.

On the other hand, the liquid nitrogen type refrigerator 280 has a liquid nitrogen tank 284 installed outside the building containing the electron storage ring 100 shown in FIG. 2, an adjustment valve 285 for adjusting the supply amount of liquid nitrogen, The configuration is provided with a gas-liquid separator 286 for preventing gas nitrogen from being mixed into the cooling pipe 282 to lower the cooling capacity, and a heater 288 for heating the nitrogen that has cooled the chevron baffle 220. As described above, this liquid nitrogen type refrigerator 280
30 is used as a second refrigerator for cooling the chevron baffle 220 and has a large cooling capacity.

[0019]

As described above, as described above, radiant heat radiated from the inner wall surface of the vacuum chamber at room temperature,
In conventional cryopumps, the reflected cryopump is mainly absorbed by a chevron baffle in order to minimize the heat absorption of the activated carbon panel.To cool the chevron baffle, a liquid nitrogen type refrigerator with a large cooling capacity is used. I have to use it.

However, the liquid nitrogen refrigerator has the following problems. (1) First, the liquid nitrogen type refrigerator consumes a large amount of liquid nitrogen as a refrigerant. For example, the type used for an electron storage ring costs several million yen per year, and the maintenance cost is low. It is too big. (2) Next, as described above, the liquid nitrogen type refrigerator includes:
Equipment such as a tank for liquid nitrogen, a pipe connecting the inside and outside of the building, a gas-liquid separator, and the like is required, and the equipment cost is excessive, and a space for installing them is required. (3) In the handling of liquid nitrogen, the person in charge of production and safety is required to manage the product under the High Pressure Gas Control Law, and the management burden is excessive.

The present invention solves the above-mentioned problems (problems) and reduces the radiant heat to the chevron baffle with a simple configuration, and also improves the cooling efficiency of the chevron baffle to reduce equipment and maintenance costs. It is an object of the present invention to provide a reduced cryopump and an electron storage ring provided with the cryopump to reduce equipment costs.

[0022]

According to a first aspect of the present invention, there is provided a cryopump comprising a chevron baffle, an activated carbon panel, and a shield container for accommodating the chevron baffle and the activated carbon panel. In a cryopump comprising a cryopanel incorporated therein, a first refrigerator for cooling the activated carbon panel, and a second refrigerator for cooling the chevron baffle, inner walls of the chevron baffle and the vacuum chamber Between
It was configured to provide a shield plate for blocking radiant heat radiated from the inner wall surface of the vacuum chamber.

With this configuration, the radiant heat radiated from the inner wall surface of the vacuum chamber and the SR reflected from the inner wall surface can be shielded, so that the cooling efficiency of the chevron baffle can be improved and the maintenance cost of the cryopump can be reduced. it can.

In the cryopump according to a second aspect, the second refrigerator for cooling the chevron baffle includes:
It was configured to use a small helium refrigerator.

As a result of reducing the cooling capacity of the chevron baffle, such a configuration becomes possible, and the use of a liquid nitrogen type refrigerator is not required, so that equipment costs and maintenance costs can be reduced, and cryopump management becomes easier. .
In addition, the cooling temperature of the chevron baffle can be reduced to a temperature very low, the efficiency of adsorbing moisture and the like is improved, and the performance of the cryopump is improved.

In the cryopump according to the third aspect,
The shield plate was formed so as to have an L-shaped cross section.

With this configuration, it is possible to shield the radiation heat and the reflection of SR from the inner wall surface of the side surface of the vacuum chamber, thereby improving the cooling efficiency of the chevron baffle and further reducing the maintenance cost.

In the cryopump according to the fourth aspect, the shield plate is formed by using aluminum as a material of the shield plate and plating the aluminum material with silver.

With this configuration, the radiation efficiency of the shield plate and the reflection efficiency of SR are increased, and the cooling efficiency of the chevron baffle is further improved.

In the cryopump according to the fifth aspect, the shield plate is supported by the shield container via a support member formed by plating a heat conductive material such as copper with silver.

With this configuration, since the shield plate can be cooled together with the shield container, radiant heat from the shield plate is almost eliminated, the cooling efficiency of the chevron baffle is further improved, and the maintenance cost of the cryopump can be further reduced. .

In the electron storage ring according to the present invention, the electron storage ring includes a plurality of bending electromagnets, and stores an electron (including positron) beam at a desired energy in a closed orbit. Claims 1 to 5
The cryopump according to any one of the above.

With this configuration, the configuration of the cryopump itself is simplified, and the building in which the electron storage ring is installed can be saved in space, and the equipment cost and maintenance cost of the electron storage ring can be significantly reduced. it can.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a cryopump according to the present invention will be described with reference to FIG. FIG. 1 is a vertical sectional side view for explaining an embodiment of a cryopump 10 of the present invention. In FIG. 1, the same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.

First, the cryopump 10 according to the present embodiment
Will be described. The main configuration of the cryopump 10 of the present embodiment is similar to that of the conventional cryopump 200 shown in FIG.
0, a box-shaped shield container 230 for blocking radiant heat from the inner wall 300a of the vacuum chamber 300, and an activated carbon panel 24 supported and attached inside the container 230 by a heat insulating material.
0 is a cryopanel 210. As the first refrigerator for cooling the activated carbon panel 240, a small helium refrigerator 260A is used.

On the other hand, the cryopump 10 of this embodiment
As shown in FIG. 1, the configurational feature between the chevron baffle 220 and the inner wall surface 300 a of the vacuum chamber 300 is
That is, a shield plate 20 for shielding radiant heat from the inner wall surface 300a of the vacuum chamber 300 and reflected light of the SR is attached. Further, as a second refrigerator for cooling the chevron baffle 220, a small helium refrigerator 260
B is used.

In the cryopump 10 of the present embodiment,
By attaching the shield plate 20 for shielding the radiant heat from the inner wall surface 300a of the vacuum chamber 300, the radiant heat can be blocked, so that the cooling efficiency of the chevron baffle 220 is improved and the cryopanel 21
0, the amount of heat absorbed by the entire helium refrigerator 2 is reduced without using a liquid nitrogen refrigerator having a large refrigeration capacity.
Even at 60B, it can be cooled sufficiently.

Thus, the conventional cryopump 200
In addition to reducing the equipment cost and maintenance cost, which have been problems, the management of the second refrigerator 260B becomes easier. In addition, since the cooling is performed by the small helium refrigerator 260B, the cooling temperature of the chevron baffle 220 decreases, the adsorption capacity of the cryopump 10 improves, and the performance as a vacuum device improves.

The cryopump 10 according to the present embodiment
In this example, as shown in FIG. 1, aluminum was used as the material of the shield plate 20, and the aluminum material was plated with silver, and the cross-sectional shape was formed in an L-shape. When the shield plate 20 is formed in an L-shaped cross section, not only radiant heat from the bottom inner wall surface 300a of the vacuum chamber 300 but also radiant heat from the side inner wall surface 300a can be shielded. Also, by plating the shield plate 20 with silver on an aluminum material,
The weight reduction, the reduction of heat capacity, the improvement of the reflection efficiency of radiant heat, and the cooling efficiency of the chevron baffle 220 are further improved.

Further, the cryopump 10 according to the present embodiment
Then, as shown in FIG. 1, a shield plate 20 is provided via a support member 30 formed by silver plating copper, which is a heat conductive material.
It is supported by the chevron baffle 220. In this way, as the chevron baffle 220 is cooled, the shield plate 20 itself is also cooled, so that a situation in which the temperature of the shield plate 20 rises and radiation heat is emitted can be prevented. In addition, heat absorption of the support member 30 can be prevented by plating the support member 30 with silver. Accordingly, the cooling efficiency of the chevron baffle 220 is further improved, and the cryopump 1
0 is further improved.

In the cryopump 10 of the present embodiment,
By attaching the shield plate 20, the cooling efficiency of the chevron baffle 220 is improved, and the cryopanel 210
A qualitative explanation of the decrease in the total amount of absorbed heat is as follows. The amount of radiated heat emitted from the inner wall surface 300a of the vacuum chamber 300 to the cryopanel 210 is unchanged, but the radiated heat reflected by the shield plate 20 having a large reflectivity. Is increased and the radiant heat directly incident on the black chevron baffle 220 is reduced, so that the amount of heat absorbed by the cryopanel 210 is reduced as a whole.

As described above, it can be qualitatively predicted that the heat absorption in the cryopanel 210 can be considerably prevented.
In the cryopump 10 of the present invention, a strict simulation is performed for a specific configuration. Hereinafter, a calculation result by the simulation will be described with reference to FIG.

Actually, each parameter of the vacuum chamber 300, the cryopanel 210, the chevron baffle 220 and the like using the cryopump 10 is shown in Table 1. Table 1 Parameter Symbol Numerical value Surface area inside vacuum chamber S _H ... 2.48 m ² cryopanel outer surface area S _L … 1.597 m ² Chevron baffle surface area S _LS … 0.65 m ² Vacuum chamber surface radiation ε _H ・ ・ ・ 0.1 Cryopanel surface radiation ε _L ・ ・ ・ 0.018 Chevron baffle surface radiation ε _LS・ ・ ・ 1.0 Vacuum chamber inner wall surface temperature _TH ・ ・ ・ 300 K Cryopanel surface temperature T _L ... 70 K

On the other hand, the amount of heat absorbed by radiant heat is generally given by equation (1).

(Equation 1)

First, in the conventional cryopump 200, the radiation heat absorbed by the chevron baffle 220 when the shield plate 20 is not attached is calculated.
By substituting the above parameters into equation (1), the total amount of radiant heat Q ′ incident on the entire surface of cryopanel 210
_S becomes Q ′ _S = 107.6 W.

As described above, the surface of the chevron baffle 220 is plated with black chrome. Therefore, assuming that all the radiant heat incident on the chevron baffle 220 is absorbed by the chevron baffle 220, the radiation ε _LS is set to ε _LS = 1.0 as shown in Table 1 above, and the chevron baffle 220 absorbs the radiation ε _LS. heat Q _S which is the area ratio, the equation (2) can be calculated as Q _S = 43.8W. Q _S = Q ′ _S × (S _LS / S _L ) (2)

Similarly, the amount of heat Q ′ _L absorbed by the surface of the cryopanel 210 other than the chevron baffle 220 is as follows. The surface of the shield container 230 is silver-plated, the reflection efficiency is high, and the radiation ε ′ _L of the surface is shown in Table 1. As shown, ε ' _L =
Since it is set to 0.018, it is substituted into equation (1),
Q ′ _L = 7.07 W. Therefore, the total amount of heat Q ′ absorbed by the entire conventional cryopanel 210 from the radiant heat of the inner wall surface 300 a of the vacuum chamber 300 is: Q ′ = 50.87 W
Becomes As described above, in the conventional cryopump 200, the liquid nitrogen type refrigerator 28 serving as the second refrigerator is used.
It was cooled at zero.

Next, the total amount of heat Q absorbed by the cryopanel 210 when the shield plate 20 is attached is calculated. First, the amount of heat Q _L which cryopanel 210 and the shield plate 20 is absorbed, into Equation (1), Q _L = 13.8
W. Here, since the shield container 230 and the shield plate 20 are silver-plated, the surface radiation ε ′ _L is set to ε ′ _L = 0.018 as shown in Table 1.
It is shown that the attachment of the high-reflectance shield plate 20 significantly reduces the absorption of radiant heat.

Meanwhile, the radiant heat Q ₁₂ coming through the opening of the shield plate 20 needs to be considered. Shield plate 20
Is set to be F = 0.5 even if the incidence coefficient F is large, and considering that there are two openings, Q ₁₂ is calculated to be 4.9 W. it can. However, the calculation was performed according to the following equation (3). ^{_{Q 12 = 5.67 × 10 -8 ·}} ε H · ε L · F · S H (T H 4 -T L 4) (3) Therefore, the cryopanel 210 overall and the shield plate when fitted with a shield plate 20 Total heat Q absorbed by 20
Becomes Q = Q _L + Q ₁₂ = 18.7 W. That is, the total heat quantity Q ′ absorbed by the entire conventional cryopanel 210 =
It can be seen that compared to 50.87 W, it is suppressed to about 1/3.

That is, as compared with the amount of heat absorbed by the cryopanel 210 by the conventional cryopump 200, the amount of heat absorbed by the cryopanel 210 of the present embodiment includes the amount of heat absorbed by the shield plate 20. Significant reduction is shown. Therefore, it is understood that a small helium refrigerator 260B can be sufficiently used as the second refrigerator for cooling the chevron baffle 220, the shield container 230, and the shield plate 20.

In the above simulation, the influence of the SR reflected light is not taken into account. SR also shield plate 2
0, the cooling efficiency of the chevron baffle 220 is
It is easily anticipated that it will be further improved by attaching. Therefore, the cryopump 10 of the present embodiment
Then, the amount of heat absorbed greatly decreases, so the shield container 2
It is understood that even if the cooling capacity of the refrigerator that cools the 30, the shield plate 20, and the chevron baffle 220 is small, it is possible to sufficiently cope with it.

By the way, in the above simulation, the cryopump 10 of the present invention uses the cryopanel 21
The structure of 0 itself has not changed. Therefore, the heat quantity absorbed by the activated carbon panel 240 is not considered.
However, since the radiant heat incident on the chevron baffle 220 can be significantly reduced by attaching the shield plate 20, it can be easily expected that the radiant heat reaching the activated carbon panel 240 through the chevron baffle 220 can also be significantly reduced. Therefore, the activated carbon panel 240
Helium refrigerator 26, which is the first refrigerator for cooling water
The burden of 0A is also reduced, and the maintenance cost can be further reduced.

The cryopump of the present invention is not limited to the above-described embodiment, but can be variously modified. For example, the material and shape of the shield plate are not limited to those described in the above embodiment. Further, the refrigerator for cooling the chevron baffle is, of course, not limited to the small helium refrigerator.

Finally, an electron storage ring using the cryopump of the present invention will be briefly described. With the conventional electron storage ring using a cryopump, a liquid nitrogen tank is installed outside the building that houses the electron storage ring,
A cooling pipe connecting the outside and the inside had to be installed, and space for installing equipment such as a gas-liquid separator had to be secured, and initial investment including the structure of the building was excessive. Further, as described above, the maintenance and management costs of the liquid nitrogen type refrigerator were too large. Therefore, by using the cryopump of the present invention, the initial construction cost and the running cost of the electron storage ring can be reduced.

[0055]

The cryopump or the electron storage ring according to the present invention has the following excellent effects because it is configured as described above. (1) In the cryopump of the present invention, a shield plate is provided between the chevron baffle and the inner wall surface of the vacuum chamber to block radiant heat radiated from the inner wall surface of the vacuum chamber. Then, since the radiant heat radiated from the inner wall surface of the vacuum chamber and the SR reflected from the inner wall surface can be shielded, the cooling efficiency of the chevron baffle is improved and the maintenance cost of the cryopump can be reduced.

(2) As described in claim 2, if a small helium refrigerator is used as the second refrigerator for cooling the chevron baffle, a liquid nitrogen type refrigerator is not required, so that the equipment can be used. Cost and maintenance costs can be reduced, and cryopump management becomes easier. (3) In addition, the cooling temperature of the chevron baffle can be lowered to a temperature very low, the efficiency of adsorbing moisture and the like is improved, and the performance of the cryopump is improved.

(4) As described in claim 3, when the shield plate is formed to have an L-shaped cross section, radiant heat from the inner wall surface of the side surface of the vacuum chamber and reflection of SR can be shielded. The cooling efficiency of the chevron baffle is improved, further contributing to a reduction in maintenance costs.

(5) As described in claim 4, aluminum is used as the material of the shield plate, and the aluminum plate is plated with silver to form the shield plate. The reflection efficiency of SR is increased, and the cooling efficiency of the chevron baffle is further improved.

(6) As described in claim 5, when the shield plate is supported by a shield container via a support member formed by plating a heat conductive material such as copper with silver, the shield plate is formed. Since cooling can be performed together with the chevron baffle, it is not necessary to consider the radiant heat from the shield plate, so that the cooling efficiency of the chevron baffle is further improved, and the maintenance cost of the cryopump can be further reduced.

(7) The electron storage ring according to the present invention is provided with a plurality of bending electromagnets so as to store an electron (including positron) beam with a desired energy in a closed orbit. When the cryopump according to any one of claims 1 to 5 is provided as a vacuum device in the electron storage ring, the configuration itself of the cryopump is simplified, and a space where the electron storage ring is installed is reduced in space. This makes it possible to significantly reduce the equipment cost and maintenance cost of the electron storage ring.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing an embodiment of a cryopump of the present invention.

FIG. 2 is a plan view showing a basic configuration of an electron storage ring to which the cryopump of the present invention is attached.

FIG. 3 is a vertical sectional side view showing a structure of a conventional cryopump.

[Explanation of symbols]

10: cryopump 20: shield plate 30: support material 210: cryopanel 220: chevron baffle 240: activated carbon panel 260, 260A: small helium refrigerator (first refrigerator) 260B: small helium refrigerator (second refrigerator) Machine) 300: vacuum chamber 300a: inner wall of vacuum chamber

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G085 AA13 BD06 BD07 BE02 BE06 BE07 EA01 3H076 AA26 AA27 BB43 BB45 CC54 CC55

Claims (6)

[Claims] 1. A cryopanel including a chevron baffle, an activated carbon panel, a shield container accommodating the chevron baffle and the activated carbon panel, and incorporated in a vacuum chamber, and a first refrigerator for cooling the activated carbon panel. A cryopump provided with a second refrigerator for cooling the chevron baffle, wherein a shield plate for shielding radiant heat radiated from the inner wall surface of the vacuum vessel is provided between the chevron baffle and the inner wall face of the vacuum vessel. A cryopump characterized by being provided. 2. A second cooling device for cooling the chevron baffle.
The cryopump according to claim 1, wherein a small helium refrigerator is used as the refrigerator. 3. The cryopump according to claim 1, wherein the shield plate has an L-shaped cross section. 4. The shield plate according to claim 1, wherein said shield plate is formed by using aluminum as a material of said shield plate and plating said aluminum material with silver. Cryopump. 5. The shield plate is supported by the shield container via a support member formed by plating a thermally conductive material such as copper with silver.
A cryopump according to any one of the above. 6. An electron storage ring comprising a plurality of bending electromagnets for storing an electron (including positron) beam at a desired energy in a closed orbit, as a vacuum device. An electron storage ring comprising the cryopump described in (1).