JPS63183280A - Cryopump - Google Patents

Abstract

PURPOSE:To improve the constitution of a means for cooling a first gas introducing piping path for improving the efficiency of cooling when the condensed layer of first gas as an adsorbing medium acting on the exhaust surface cooled to extremely low temperature in vacuum is condensed and a second gas is adsorbed to the condensed layer to be exhausted. CONSTITUTION:Exhausted gas introduced from a exhausted vacuum container through an intake port 45 reaches an exhaust surface 1 through respective baffles 32, 21. Since this exhaust surface 1 together with a shepron type baffle 21 is cooled by liquid helium in a liquid helium reservoir 2, components such as hydrogen or the like other than helium are exhausted by the condensing action in the baffle 21 and helium is exhausted by the adsorbing action of a condensed argon layer sprayed on the exhaust surface 1 from argon jetting pipes 12..., cooled and condensed. Then, a support member 53 integral with a manifold 13 connected to the argon jetting pipes 12... is supported by a radiation shield 33 cooled to the boiling point of liquid nitrogen through respective adiabatic support members 51, 52 and a support member 54.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention has an adsorption medium cooled to an extremely low temperature that exhausts a second gas such as hydrogen or helium by an adsorption action or a cryotrapping action. Regarding a cryopump, particularly in one in which the adsorption medium is a first gas condensation layer condensed on a surface cooled to an extremely low temperature, the configuration of a cooling means for a first gas introduction piping route forming the gas condensation layer. Regarding the improved cryopump.

(Prior Art) An example will be explained in which a gas condensation layer that is formed on a cryogenic surface and acts as an adsorption medium is formed using argon, which is a first gas.

Conventionally, argon is condensed on a metal surface cooled by liquid helium, and the helium is exhausted by the adsorption effect or cryotrapping effect of this argon condensation layer, as described in one document (T, H, Batzer, R.

E, PaLr1ck, and Ii, R, Ca1
1. Vac, Sci.

Technol, Vil 18 Na 3. Ap
An example is shown in Fig. 1 of Ril, pH 25, 1981). Fi on page 1126J of the above document,
FIG. 8 schematically shows a vertical cross-sectional view of a cryopump that exhausts helium or hydrogen by the adsorption action or cryotrapping action of the argon condensation layer shown as 1.

In Figure 8, (1) is the exhaust surface that forms a condensed layer of argon and exhausts helium, (2) is the liquid helium reservoir that cools the exhaust surface (1), and (4) is the liquid in the liquid helium reservoir. Helium population. An outlet for gaseous helium evaporated from the liquid helium reservoir is not shown.

(12) is an argon blow-off pipe that blows argon onto the exhaust surface (1) (the argon blow-off hole is not shown); (13)
is the manifold of the argon outlet pipe (12), (14)
(17) is an argon inlet pipe that supplies argon from outside the vacuum vessel to the manifold, and (17) is an argon inlet connected to an argon introduction device (not shown).

(18) is a heater attached to the manifold (13). (20) is a support that is connected to the argon outlet pipe (12) and the radiation shield (33) (described later) so as to have good thermal contact and supports the argon outlet pipe (12) and the manifold (13). It is a member. (21)
is a chevron-shaped baffle cooled by a liquid helium reservoir (2), and (23) is a gas-liquid separator for the liquid helium reservoir.

(25) is the liquid helium inlet of the gas-liquid separator (23) (the gas helium inlet of the gas-liquid separator (23) is not shown)
. (:12) is a louver blind baffle, (3
3) is a radiation shield, and (34) is a liquid nitrogen reservoir. The louver blind baffle (32), the radiation shield (33), and the liquid nitrogen reservoir (34) are coupled in good thermal contact and are each cooled to near the boiling point temperature of liquid nitrogen. (41) is the cryopump container, (
42) is the lid that suspends the entire cryopump, (4
3) is the auxiliary vacuum exhaust port of the cryopump (the auxiliary vacuum exhaust device is not shown), (45) is the inlet port of the cryopump that connects the vacuum container to be evacuated (the vacuum container is not shown), (46) is the exhaust gas inlet of the cryopump.

The evacuated lambda body that has entered the evacuated gas inlet (46) from the vacuum container (not shown) through the inlet port (45) passes through the louver blind baffle (32) and the chevron baffle (21) to the exhaust surface (1). reach. In this process, components other than helium, such as hydrogen, are mainly exhausted into the chevron-shaped baffle (21) by condensation.

Helium is mainly exhausted onto the exhaust surface (1) by adsorption or cryotrapping. The exhaust surface (1) I-1 was distinguished from the adsorption action or cryotrapping action.
- The case where other gases are adsorbed without continuously forming a condensed layer consisting of an adsorption medium is called adsorption action, and the case where another gas is adsorbed by continuously forming a condensed layer is called cryotrapping action. This is because there is a custom of calling

In FIG. 8 showing the above-mentioned conventional technology, as described in the 6th to 10th lines from the top of the right column of the literature page 1126, the manifold (13) of the argon blow-off pipe is cooled with liquid nitrogen. A heater (18) is mounted which is supported in good thermal contact with the radiation shield (33) and which controls the temperature inside this manifold. The temperature of this manifold (13) is
3), so that it is cooled to approximately the boiling point temperature of liquid nitrogen by the radiation shield (33).

Also, the first gas (in this case, argon) introduced is heated to an appropriate temperature by a heater. According to this configuration, the heated argon is cooled and condensed on the cryogenic surface, so it is possible to reduce the thermal load on the cryogenic cooling surface compared to the case where the argon is directly condensed from room temperature. However, in this configuration, the radiation shield (33) cooled with liquid nitrogen is connected to the heater (
18), so the radiation shield (33)
The disadvantage was that the amount of liquid nitrogen consumed for cooling increased.

There was also the fear that the temperature of the radiation shield would rise, increasing the amount of liquid helium consumed.

(Problems to be Solved by the Invention) A cryopump that exhausts helium or hydrogen by the adsorption action or cryotrapping action of a gas condensation layer is designed to adjust the temperature of the gas introduced to form the gas condensation layer to the same temperature as that of the gas condensation layer. It is necessary to cool the exhaust surface (1), which has been cooled to an extremely low temperature, to reduce the heat load. For this reason, the inlet pipe for the gas to be used as an adsorption medium is cooled by being coupled to the radiation shield (33) of the cryopump so as to have good thermal contact. However, according to this method, the gas may be cooled too much and liquefied, so it was necessary to heat the introduction pipe (14) with a heater (18). Therefore, the radiation shield (33) is subjected to a thermal load due to the heat generated by the heater (18), and the radiation shield (33)
), which increases the consumption of liquid nitrogen for cooling the radiation shield (33). There is also a problem that the temperature of the radiation shield (33) may rise and the amount of liquid helium consumed may increase.

In view of the above-mentioned circumstances, the present invention allows a first gas condensation layer condensed on an exhaust surface cooled to an extremely low temperature to act as an adsorption medium, and uses the adsorption action or cryotrapping action of the adsorption medium to separate a second gas condensation layer from the adsorption medium. In a cryopump that exhausts the second gas, in order to introduce the first gas for forming a gas condensation layer without liquefying it, the first gas is cooled with liquid nitrogen, radiant heat from the cryopump container, The purpose of this invention is to cool the first gas to a temperature slightly higher than the boiling point of liquid nitrogen by heat conduction through the introduction piping route, reduce the heat load applied to the cryopump, and provide an efficient cryopump.

[Structure of the invention]

(Means for Solving the Problems) In the present invention, a condensation layer condenses a first gas acting as an adsorption medium on an exhaust surface cooled to an extremely low temperature in a vacuum, and a condensation layer of the first gas acts as an adsorption medium. In a cryopump that exhausts a second gas to be exhausted into the medium or onto a condensation layer by adsorption or cryotrapping, the introduction pipe for introducing the first gas into the exhaust surface has a temperature approximately equal to the boiling point temperature of liquid nitrogen. The first gas temperature is made to be slightly higher than the boiling point of liquid nitrogen. be.

(Function) According to the present invention, even if the first gas is cooled with liquid nitrogen,
The temperature of the first gas is set in advance to a temperature slightly higher than the boiling point of liquid nitrogen by receiving heat radiation from the cryopump container and heat conduction from the introduction piping route, so the first gas is blown out to the exhaust surface. This prevents the liquid from liquefying in the blow-out pipe and making it impossible to blow out, but instead ensures that it is blown onto the exhaust surface and condensed, which increases the heat load on the cryopump.
Improve efficiency.

(Examples) Example 1 A first example of the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 11121 and FIG. 2, members having the same functions as those in FIG. 8 are given the same reference numerals, and explanations thereof will be omitted. (51) is a first heat insulating support member that thermally isolates the manifold (13) and the radiation shield (33); (52) is the radiation shield (33) connected by bolts (55) and nuts (56) for connection; and the manifold (13) from being thermally coupled; (53) is the second heat insulating support member for coupling the manifold (13) to the radiation shield (33) with bolts and nuts; The first support member (54) is a second support member fixed to the radiation shield (33). Manifold (13)
is the first support member (53) with bolts (55) and nuts (
56), the first support member (54) is fixed to the radiation shield (33). A second heat insulating support member (51).

(52) and is supported by the radiation seal torch 33). The aluminum blowout pipe (12) provided in the manifold (13) is connected to the third heat insulating support member (57).
Supported by.

Next, the operation of this first embodiment will be explained.

The manifold ' (13) is radiantly cooled by a radiation shield (33) that is cooled to approximately the boiling point temperature of liquid nitrogen, and the first. Second. Third PII thermal support member (51), (52
) and (57), it is cooled almost adiabatically, although it is slightly warmed by leakage cooling from (57). The manifold (13) is also placed in the cryopump container (4) at room temperature.
1) Heat is penetrated by radiation heating from the wall and heat transfer from the room-temperature inlet pipe (14). At this time, each heat insulating member (51)
.

The leakage cooling from (52) and (57) becomes moderately effective, and the temperature of the first gas that acts as an adsorption medium, that is, argon gas, can be cooled to a temperature slightly higher than the boiling point of liquid nitrogen without heating it with a heater. The argon blow-off pipe (1
2) It does not liquefy until it is blown out. The argon gas blown onto the exhaust surface (1) cooled to an extremely low temperature by liquid helium forms a condensation layer, acts as an adsorption medium, and removes the hydrogen and helium remaining in the cryopump container (41). Gas is exhausted by adsorption or cryotrapping. Therefore, an efficient cryopump with reduced heat load and no need for a heater can be obtained.

Example 2 A second example will be explained with reference to FIG. In Figure 3, the first
Components having the same functions as those in FIGS. 2, 2, and 8 are designated by the same reference numerals, and explanations thereof will be omitted. In Fig. 3, (19) is an argon cooling introduction pipe fixed to the radiation shield (33) for good thermal contact, and (61) is an argon cooling introduction pipe (14) and the argon cooling introduction pipe. A flexible tube (62) connects the argon cooling introduction pipe (19) and the manifold (33). The rest is the same as in Example 1.

With this configuration, the introduction piping route can be thermally anchored to the radiation shield (33), which is cooled to approximately the boiling point temperature of liquid nitrogen, which has the advantage of shortening the cooling time of the manifold (13). . In addition, the flexible tubes (61) and (62) have the advantage of reducing the heat load due to heat conduction and making it possible to adjust the cooling temperature of the manifold (33), and the same effects as in Example 1 can be obtained. .

Example 3 The third example is explained in Figure 4.6 In Figure 4, the first example is explained.
2, 2, 3, and 8 are given the same reference numerals, but the shapes are different, so the main parts will be explained again. In FIG. 4, (1) is an exhaust surface, (2) is a liquid helium reservoir that cools the exhaust surface (1), and (3) is a gas-liquid separator for the liquid helium reservoir (2).

(4) is the liquid helium inlet of the gas-liquid separator (3), (5)
is the evaporated gaseous helium outlet in the gas-liquid separator (3). (11) is a blowout hole for argon, which is the first gas.

(12) is an argon blow-off pipe, (13) is a manifold for saving argon blow-off, and (14) is a manifold (13).
), and (19) is an argon cooling introduction pipe piped in good thermal contact with the radiation shield (33) for introducing argon into the external manifold (15). It is. (17) is the inlet for argon gas. (21) is a chevron-shaped baffle, (2
2) is liquid helium 1, cooling pipe, (23) is liquid helium 1
1 cooling pipe (22), (25) is the liquid helium inlet of the gas-liquid separator (23), and (26) is the gaseous helium outlet evaporated from the gas-liquid separator (23). (3
1) is a chevron-shaped baffle cooled with liquid nitrogen, (
33) is a radiation shield cooled with liquid nitrogen, (34
) is the liquid nitrogen reservoir, (35) is the liquid nitrogen population, (36) is the gaseous nitrogen outlet, (41) is the cryopump container, (4
2) is the lid, (43) is the auxiliary evacuation port, (44) is the auxiliary evacuation device, (45) is the inlet of the cryopump, (46) is the inlet of the gas to be evacuated, and (47) is the evacuated gas. It is a vacuum container. (51) is a heat insulating support member for the external manifold (15), and (53) is a support member.

(57) is a heat insulating support member for the portion where the introduction pipe (14) penetrates the radiation shield (33).

The effect of such a configuration will be described. The external manifold (15) is connected to the radiation shield (33) by sandwiching the first support member (53) and the first heat insulation support member (51) and fastening it to the radiation shield (33) with bolts and nuts.
Supported by The bolts/nuts and the heat insulating support members for the bolts/nuts are connected to an external manifold (6) (not shown).
) is thermally isolated from the radiation shield (33) by a first heat insulating support member (51) with low thermal conductivity and a heat insulating support member of bolts and nuts (not shown).

This support configuration allows the manifold (15) to be cooled by radiation cooling by the radiation shield (33) and to maintain a temperature between the radiation shield (33), which is cooled to approximately the boiling point temperature of liquid nitrogen, and the wall of the cryopump container (41), which is at room temperature. Cooling of heat insulating support member (51) of No. 1 and room temperature wall (41)
It is maintained by radiant heating. Argon gas, which acts as an adsorption medium to form a condensation layer on the exhaust surface (1), is introduced through this manifold (15) and blown out, so that it is cooled to approximately the same temperature as the manifold (15). According to this third embodiment, when a liquid cooling medium reservoir is provided inside, since the baffles (21) and (23) are arranged vertically, it is easy to install the intake port (45) horizontally. , it has the advantage of reducing the installation space.

Embodiment 4 A fourth embodiment will be explained with reference to FIG. 4 in Figure 5
Components having the same functions as those in the figures are given the same reference numerals and explanations will be omitted. In FIG. 5, since the chevron-shaped baffle (21) cooled by liquid helium shown in FIG. 4 is not provided, helium, hydrogen, and other gases to be exhausted are simultaneously exhausted onto the exhaust surface (1). When there is no particular need to distinguish the helium exhaust surface (1) from the gas exhaust surface other than helium, the structure has the advantage of being fi15QL.

Embodiment 5 A fifth embodiment will be explained with reference to FIG. FIG. 6 shows a case where a helium refrigerator is used to cool the gas exhaust surface (1).6 In FIG. 6, members having the same functions as those in FIG. In Figure 6, (7I) is a helium refrigerator, (72) is the first stage cooling section of the helium refrigerator that is cooled to approximately the boiling point temperature of liquid nitrogen, and (73) is the helium refrigerator that is cooled to approximately 20K. The second stage cooling section (74) is the third stage cooling section of the helium refrigerator which is cooled to approximately the boiling point temperature of liquid helium. (Compressor, heat exchanger, JT valve, etc. are not shown). (75) is the third
A cooling plate fixed in good thermal contact with the stage cooling section, (
1) is the exhaust surface cooled by the third stage cooling section, (77) is the first radiation shield cooled by the third stage cooling section, (78)
is a chevron-shaped baffle cooled in the third stage cooling section, (
79) is a second radiation shield cooled by the first stage cooling section, and (80) is a chevron-shaped baffle cooled by the first stage cooling section. In this way, a gas condensation layer is formed on the exhaust surface (1), which acts as an adsorption medium. Gases other than helium to be exhausted are mainly handled by chevron-shaped baffles (
80) Exhausted to the top.

According to this embodiment, it is possible to construct a cryopump without using liquefied gas as a refrigerant, so there is an advantage that handling becomes easier.

Embodiment 6 A sixth embodiment will be explained with reference to FIG. FIG. 7 shows a configuration in which the chevron-shaped baffle (78), which is cooled to approximately the liquid helium temperature, is omitted when a helium refrigerator is used as a means for cooling the exhaust surface (1) shown in FIG. 6. In FIG. 7, members having the same functions as those in FIG. 4 are given the same reference numerals and their explanations are omitted.6 Embodiment 6 shown in FIG. 7 does not have a chevron-shaped baffle that is cooled to approximately the liquid helium temperature. When the first gas is argon gas, helium, hydrogen, and other gases are simultaneously exhausted to the exhaust surface (1)-H. There is an advantage that the configuration becomes simple when there is no need to distinguish the helium exhaust surface from the exhaust surface of other gases.

In each of the above embodiments, argon was used as the gas in the adsorption medium cylinder 1, but other gases such as nitrogen may also be used.

〔Effect of the invention〕

As described above, according to the present invention, the introduction tube for the first gas acting as an adsorption medium is inserted into the vacuum space between the member cooled to approximately the boiling point temperature of liquid nitrogen and the member at approximately room temperature. Since it is adiabatically supported from a member that is cooled to the boiling point temperature of nitrogen, the second gas to be adsorbed has a temperature slightly higher than the boiling point of liquid nitrogen, and the gas can be properly absorbed without increasing the thermal load on the cryopump. It is now possible to cool down. Therefore, an efficient cryopump with reduced heat load can be provided.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing a first embodiment of the cryopump of the present invention, FIG. 2 is an enlarged view showing the adiabatic support portion of FIG. 1, and FIGS. FIG. 8 is a longitudinal sectional view showing a conventional cryopump. Explanation of symbols ■... Helium exhaust surface, 2... Liquid helium reservoir, 3... Gas-liquid separator, 4... Liquid helium inlet. 5... Liquid helium outlet, 11... Argon blow-off hole, 12... Argon blow-off pipe, 13... Manifold. 14... Argon introduction pipe, 15... External manifold, 17... Argon inlet, 18...
・Heater, 19... Cooling introduction pipe, 20.
...Support member, 21...Chevron-shaped baffle made of liquid helium. 22... Liquid helium cooling pipe, 23... Gas-liquid separator, 24... Support member, 25... Liquid helium inlet, 26... Gas helium outlet. 31...Chevron-shaped baffle with liquid nitrogen, 33
...Radiation shield using liquid helium, 34...Liquid nitrogen reservoir, 35...Liquid nitrogen inlet. 36... Gaseous nitrogen outlet, 41... Talio pump container, 42... Lid, 43
... Auxiliary vacuum exhaust port, 44 ... Auxiliary V (air exhaust device), 45 ... Intake [ ], 46 ... Exhausted gas inlet, 47 ... Vacuum container. 51 ... First Heat insulation support member, 52... Second heat insulation support member. 53... First support member, 54... Second support member, 55... Bolt, 56... Nut, 57...
...Third heat insulation support member, 61...Flexible tube. 62... Flexible tube, 71... Helium refrigerator, 72... First stage cooling section, 73...
Second stage cooling section, 74... Third stage cooling section, 75... Cooling plate, 77... First radiation shield, 78... Chevron shaped baffle. 79...Second radiation shield, 80...Chevron-shaped baffle 7 Agent Patent attorney Inoue --- Rikizutsu 2-

Claims (4)

[Claims] (1) A condensation layer condenses a first gas that acts as an adsorption medium on an exhaust surface cooled to an extremely low temperature in a vacuum, and a second gas that is to be evacuated into or on the condensation layer of the first gas. In a cryopump that exhausts gas by adsorption action or cryotrapping action, the introduction pipe for introducing the first gas into the exhaust surface has an adiabatic support part that is cooled to approximately the boiling point temperature of liquid nitrogen, and an adiabatic support part that is cooled to approximately the boiling point temperature of liquid nitrogen. and a part that receives heat radiation in vacuum from the cryopump container, and
A cryopump characterized by having a gas temperature slightly higher than the boiling point of liquid nitrogen. (2) The first gas is cooled by a radiation shield for reducing heat radiation from a room temperature section to an exhaust surface that is cooled to approximately the boiling point temperature of liquid helium. Cryopump described in section. (3) The cryopump according to claim 2, wherein the first gas introduction pipe is provided with a manifold that is slightly adiabatically supported by the radiation shield. (4) The cryopump according to any one of claims 1 to 3, wherein the first gas is argon.