JPH04194377A - Cryopump - Google Patents

Abstract

PURPOSE:To improve the extent of exhausting velocity by installing a cryopanel at the rear side of the cryopanel set up orthogonally with a gas molecule inflow port face, where only the conventional heat shield has so far been set up, in parallel with the gas molecule inflow port. CONSTITUTION:A gas molecule flows in an arrow direction from a gap between front shield plates 1. A cryopanel 2 is installed in the back of the front shield plate 1 almost perpendicular to a gas molecule port face. Another cryopanel 3 is installed in parallel with a gas inflow port, and two groups of louvers 5 and chevrons 6 are installed in these cryopanels 2, 3. Thus, a cryopanel surface is increased and thereby a gas exhausting velocity is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a structure in which the pumping speed is increased by optimizing the placement position of the cryopanel in a louver-blind cryopump.

[Prior Art] As described in Japanese Unexamined Patent Publication No. 169682/1982, a conventional device uses a cryopanel that has been cooled to an extremely low temperature with liquid helium or the like, at a angle almost perpendicular to the plane of the gas molecule inlet. In addition, multiple sheets are arranged at regular intervals.

[Problem to be solved by the invention] In conventional cryopumps, the placement of cryopanels is not optimized in consideration of the movement of incident gas particles, resulting in a problem that the pumping speed per unit volume of the cryopump is small. was there.

However, the neutral particle injection device used in recent large-scale nuclear fusion experimental devices requires a cryopump with a large pumping capacity of hydrogen 9 deuterium. On the other hand, the neutral particle injection device
Since it is constructed from a vacuum container, the aperture area and volume of the beam facing surface of the cryopump installed inside are reduced. That is, it is important to reduce the manufacturing cost by making the vacuum container smaller by achieving high performance and miniaturization.

An object of the present invention is to increase the pump pumping speed by optimizing the arrangement of cryopanels that serve as pumping surfaces within a cryopump having the same volume.

[Means for Solving the Problems] In order to achieve the above-mentioned goals, the present invention provides gas molecules at the rear side of the cryopanel, which is arranged perpendicularly to the gas molecule inlet face, where only a heat shield was installed. A cryopanel was installed parallel to the inlet surface.

[Operation] Gas particles that enter from the gas molecule inlet surface hit the heat shield plate and are reflected repeatedly, and are condensed and exhausted by the cryopanel only when they enter the cryopanel at an angle of incidence that allows them to pass through the heat shield plate. Ru. Therefore, for example, gas particles that are incident at an incident angle that is close to a right angle to the gas molecule inlet surface will be reflected by the heat shield and exit the cryopump as is, which is one of the reasons why the pumping speed is not improved. There is. Therefore, by installing a cryopanel parallel to the gas molecule inlet surface on the rear side of the cryopanel placed at right angles to the gas molecule inlet surface, The pumping speed is improved by reducing the number of particles that are reflected by the heat shield plate and exit the cryopump without being absorbed by the cryopanel.

[Example] Hereinafter, an example of the present invention will be described with reference to FIG. Low-temperature front heat shield plate 1 placed on the front of the cryopump
Gas molecules to be evacuated flow into the cryopump from between the two in the direction of the dashed arrow. An extremely low-temperature cryopanel 2 is installed behind the front heat shield plate 1 almost perpendicular to the cryopump gas molecule inlet surface, and a cryopanel 3 is installed parallel to the cryopump gas molecule inlet surface. It is installed in front of the rear heat shield plate 4 and behind the cryopanel 2. A group of low-temperature louvers 5 tilted at an angle α are provided on the left and right sides of the cryopanel 2. Further, a chevron group 6 is provided on the cryopump gas molecule inlet side of the cryopanel 3.

The extremely low temperature cryopanels 2 and 3 are arranged so as not to be directly visible from the direction of the cryopump gas inlet. Conventionally, gas molecules that flowed into the cryopump from the inlet would repeatedly collide with the louver 5 and the rear heat shield plate 4, and some gas molecules would flow out from the inlet, but by providing the cryopanel 3, Therefore, among the gas molecules that conventionally flowed out of the cryopump by impact and reflection on the rear heat shield plate 4, those that were able to pass through the chevrons 6 can be solidified and adsorbed on the cryopump 3.

The proportion of gas molecules flowing out can be reduced. Therefore, according to this embodiment, the gas pumping speed can be increased compared to the conventional louver-blind cryopump.

Figure 2 shows a conventional louver-blind type CLA bomb.

FIG. 3 shows another embodiment of the present invention, in which the heat shield installed on the gas inlet side of the cryopanel 3 is changed from the chevron type shown in FIG. 1 to a louver type. In this embodiment as well, there are gas molecules adsorbed to the cryopanel 3, so a similar effect can be obtained.

FIG. 4 shows another embodiment of the present invention.
The difference from FIG. 3 is that the cryopump 3 is not separated between the cryopanels 2 and has approximately the same width as the rear heat shield plate 4. According to this structure, since the cryopanel 3 is not separated, there is an advantage that the structure is simple.

〔Effect of the invention〕

According to the present invention, since the cryopanel can be installed parallel to the gas inlet of the rear heat shield plate, the cryopanel surface can be increased and the gas exhaust speed can be increased.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a cryopump explaining an embodiment of the present invention, FIG. 2 is a sectional view of a conventional louver blind type cryopump, and FIGS. 3 and 4 are sectional views of a cryopump according to other examples. FIG. 3 is a sectional view of the pump. ■...Front heat shield plate, 2...Cryopanel,
3... Cryopanel, 4... Rear heat shield plate,
5... Figure 1 Figure 2 Figure 31 Cow Figure 4 -

Claims (1)

[Claims] 1. A cryopump consisting of a cryopanel cooled to an extremely low temperature for condensing and adsorbing gas molecules, and a heat shield plate cooled to a low temperature to protect the cryopanel from high-temperature radiant heat. , A cryopanel is installed parallel to the gas molecule inlet surface on the rear side of the cryopanel in which the cryopanel is arranged at right angles to the gas molecule inlet surface and at right angles to the gas molecule inlet surface. pump.