JPS5941270B2 - Electric discharge cleaning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge cleaning device that performs discharge cleaning of a wall surface of a vacuum apparatus using PIG discharge.

Conventionally, when realizing an ultra-high vacuum device, the wall surface of a vacuum container is generally heated, and the adsorbed molecules are desorbed from the wall surface and discharged outside the vacuum container or accumulated in an accumulation type pump inside the vacuum container. A so-called paying process is performed.

However, in this paking process, it is very difficult to desorb adsorbed molecules whose desorption activation energy is large from the wall surface of the vacuum vessel, and therefore, it was not possible to perform a sufficient degassing process.

Furthermore, in nuclear fusion devices, particle accelerators, and the like, even after pacing processing, a large amount of residual molecules are released due to high-energy particle irradiation.

Furthermore, there are cases in which the above-mentioned paking process cannot be performed due to the material, structure, handling technique, etc. of the vacuum container (for example, a torus container).

Therefore, in recent years, discharge cleaning using low pressure gas discharge, high frequency discharge, etc. has been performed.

This discharge cleaning uses electrodes placed opposite to the inner wall surface of the vacuum container to generate a discharge between the inner wall surface and the electrodes to degas the inner wall surface, and is relatively simple and sufficient. Degassing treatment can be performed.

However, this type of discharge cleaning apparatus has a problem in that the particle flux incident on the wall surface of the vacuum vessel becomes non-uniform due to the characteristics of the generated plasma, resulting in uneven discharge cleaning.

Furthermore, in order to generate plasma, it was necessary to raise the pressure of the working gas to a low vacuum region, and as a result, there was a risk that the vacuum surface would be contaminated by the moving gas.

Furthermore, since the energy possessed by the particles incident on the wall surface of the vacuum container is a part of the energy consumed in the discharge, there is a drawback that the energy efficiency is very poor.

The present invention was made in consideration of these circumstances, and its purpose is to uniformly and stably discharge the vacuum surface of ultra-high vacuum equipment such as nuclear fusion devices and particle accelerators using PIG discharge. It is an object of the present invention to provide a discharge device that can be cleaned and that can perform the discharge cleaning with high energy efficiency.

First, the present invention will be explained in detail.

This invention provides for a discharge to be generated between an anode provided inside a magnetic field generator and having an opening extending through the magnetic field generator in the direction of magnetic field generation, and a cathode spaced apart and facing each other at openings at both ends of the anode. The magnetic field generating device is housed in an airtight container suitable for use in an ultra-high vacuum, and the magnetic field generating device is By cooling with cooling water, etc., P can be removed without disturbing the ultra-high vacuum.
A strong magnetic field necessary for IG discharge is generated, and an opening extending outward from the center of the opening of the anode provided at one cathode of the PIG electrode placed in the strong magnetic field is connected to the inner wall surface of the vacuum container, etc. By irradiating the inner wall surface of the vacuum container with a particle beam by the PIG discharge, the inner wall surface of the vacuum container can be stably discharge cleaned.

Furthermore, the magnetic field generator and the PIG electrode are mutually fixed and integrated, and the structure is such that they can be moved arbitrarily within the vacuum container, thereby making it possible to perform the discharge cleaning evenly and efficiently. .

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the schematic structure of the same embodiment.

In the figure, reference numeral 1 denotes an annular container having a U-shaped cross section, and a hollow disc-shaped lid 2 is airtightly attached to one end opening of the container 1. As shown in FIG.

The container 1 and lid 2 are each made of non-magnetic stainless steel suitable for use in an ultra-high vacuum, and the container 1 and lid 2 form an airtight container.

This airtight container 3 houses a magnetic field generating device 4, which will be described later.

Further, a disk-shaped first cathode 5 is airtightly attached to the inner circumferential surface of the airtight container near one end (lid 2 side).

This first cathode 5 is made of non-magnetic stainless steel or the like,
The central portion is made of a high melting point metal 5a such as molybdenum, and the cathode 5 and the high melting point metal 5a are airtightly fixed.

A cooling water flow path 6 communicating with the inside of the airtight container J is formed in a space surrounded by the cathode 5, the container 1, and the lid 2.

Further, an annular second cathode 7 is airtightly attached to the inner peripheral surface of the other end of each of the airtight containers.

This second cathode 7 is made of non-magnetic stainless steel or the like, and has a central portion made of a high melting point metal 7a such as molybdenum.

Further, a cylindrical insulating tube 8 made of alumina porcelain is attached between the first and second cathodes 5 and 7 on the inner peripheral surface of the airtight container.

This insulating tube 8 prevents an inverted magnetron type parasitic discharge that is parasitic to a PIG discharge, which will be described later.

On the other hand, in the inner space of each pre-packed airtight container, that is, in the space surrounded by the outer wall of the container 1, a cylindrical anode 9 made of non-magnetic stainless steel or the like is installed coaxially with the airtight container product. .

The anode 9 is connected to one end of a current lead member 10 inserted through each through hole of the lid 2 and the first cathode 5.

The current lead member 10 is composed of an insulating tube 11 made of alumina porcelain and a conductor wire 12 passing through the inside of the insulating tube 11. The outer peripheral surface of the insulating tube 11 is connected to the cover body 2 and It is attached to each through hole of the first cathode 5.

Further, one end of the current lead member 10 is firmly fixed to the anode 9 by a conductive connecting member 14.

By attaching the Kovar ring 13 and the connecting member 14, the anode 9 is positioned and fixed.

Note that the terminal 15 on the other end side of the current lead member 10 is connected to a power feeding section (not shown).

Further, on one side near the outer periphery of the lid body 2, one end side of a support leg 24 (the metal plate 21) consisting of an ultra-high vacuum compatible metal plate 21, a rod body 22, and a flange 23 whose length is adjusted.
is attached.

The other end side of this support leg 24 (the above-mentioned flange 23)
is inserted from the wall of the vacuum device and fixed to a vacuum guide device or the like that moves freely within the vacuum device.

Further, one end of a cooling water pipe 31 made of non-magnetic stainless steel is airtightly attached to the hollow portion of the lid 2.

This cooling water pipe 31 is communicated with the cooling water flow path 6.

Further, the other end of the cooling water pipe 31 is airtightly attached to the vacuum guide device etc. via an ultra-high vacuum flange 32,
Cooling water is supplied from a cooler or the like (not shown).

Furthermore, on one side near the outer periphery of the dream body 2, a cooling water pipe 34 made of non-magnetic stainless steel and having a bellows pipe 33 is provided.
One end of the is attached airtight.

This cooling water pipe 34 is communicated with each of the airtight containers.

The other end of the cooling water pipe 34 is airtightly attached to the vacuum guide device or the like via an ultra-high vacuum flange 35.

The cooling water that is supplied to each of the airtight containers through the cooling water piping 31 and the cooling water flow path 6 and that has flowed through the airtight container 1 is discharged.

Now, the magnetic field generating device 4 is composed of, for example, a winding container 41, an air-core electromagnet 42, an epoxy resin, and the like.

The winding container 41 includes a plurality of containers 41a, 41 having different diameters.
b and 41c, each of which is housed in the container 1 sequentially from the inside to the outside.

Moreover, each of the containers 41a and 41b. 41c is made of annular non-magnetic stainless steel and each has a rectangular cross section.

Conductor windings 42a, 42b, and 42c are wound and accommodated in each of the containers 41a, 41b, and 41c, respectively.

The air-core electromagnet 42 is formed by connecting these conductor windings 42a, 42b, and 42c in series.

The lead end of this electromagnet 42 is insulated with an alumina porcelain insulating tube, and connected to terminals 43a and 43b, respectively, through a current lead member that airtightly connects the insulating tube and the lid 2 with a Kovar ring. ing.

The electromagnet 42 is excited via the terminals 43a and 43b, and a magnetic field is formed in the direction from the first cathode 5 to the second cathode 7.

Note that the winding containers 41 a and 4 l b. 41c
Each of the insides is filled with epoxy resin, and the lead ends of the electromagnet 42 are integrally molded with epoxy resin.

Thus, the air-core electromagnet 42 of the magnetic field generator 4 inside the airtight container is electrically insulated from the cooling water and cooled by the cooling water.

According to the device configured in this way, the terminal 43a
, 43bl/ic excitation power source and a discharge power source between the anode 9 and the first and second cathodes 5 and 7, the direction from the first cathode 5 to the second cathode 7 is A magnetic field is generated between the anode 9 and the first and second cathodes 5.
, 7 can generate a 1cPIG discharge.

For this reason, if the second cathode 7 is placed close to the wall surface of the vacuum chamber using a vacuum guide device or the like, the particle beam is irradiated onto the wall surface through the opening of the second cathode 7 due to the PIG discharge. .

Therefore, discharge cleaning of the wall surface of the vacuum container can be performed.

In this case, unlike conventional discharge cleaning equipment, a discharge is generated between the anode 9 and the cathodes 5 and 7, without using the wall surface of the vacuum chamber to be cleaned as an electrode for discharge, and the particle beam generated by this discharge is generated. Since it is introduced into a vacuum container and the wall surface of the container is cleaned, there are advantages such as the electric power required for discharge can be significantly reduced and the amount of working gas can be extremely reduced.

In addition, since the PIG discharge is stable in ultra-high vacuum or high-vacuum microelectrode, it is possible to perform discharge cleaning very stably and with good quality compared to conventional discharge cleaning using G7-discharge or high-frequency discharge. A clean surface can be obtained.

Furthermore, in PIG discharge, most of the energy consumed in discharge can be used to accelerate ions, so the proportion of energy involved in discharge cleaning, that is, energy efficiency, can be increased.

Further, since the magnetic field generating device 4 is cooled by cooling water and insulated from the cooling water, it can stably generate the magnetic field necessary for PIG discharge.

Furthermore, since all the vacuum surfaces exposed in the vacuum are formed of materials compatible with ultra-high vacuum, there are advantages such as being suitable for use in ultra-high vacuum or high vacuum.

FIG. 2 is a sectional view showing a schematic structure of another embodiment.

This embodiment differs from the first embodiment described above as follows:
The wall of the airtight container housing the magnetic field generator is used as an anode, and the cathode is insulated from the vacuum container.

That is, the airtight container i containing the magnetic field generating device 4 is formed in an annular shape with an opening extending toward one end.

On this airtight container i, on the other end side, there is a first cylindrical body 5 whose one end is attached to a hollow disk-shaped ultra-high vacuum flange 52.
The other end of 3 is attached and fixed.

The first cylindrical body 53 has an outer diameter that is the same as the outer diameter of the airtight container 11, and is made of non-magnetic stainless steel.

Therefore, the airtight container i has the same potential as the flange 52.

Then, the wall surface of the opening of the airtight container i is used as the anode 51a.

Further, on the other end side of the airtight container i, there are a current lead member 54 of the magnetic field generator (and two cooling water supply and discharge pipes 55).
is attached.

On the other hand, the first cathode 56 is disposed close to and opposite to the opening surface of the other end of the airtight container i.

The first cathode 56 has a concave portion at one end (above the container i) and a through hole in the center. A high melting point metal 56a is fitted and fixed.

A pipe 57 made of non-magnetic stainless steel is attached to the other end of the first cathode 56.

This piping 57 is connected to a fluid supply pipe or the like via an ultra-high vacuum flange 58.

The discharge operating gas is introduced into the opening of the airtight container 51 through the pipe 57, the through hole of the cathode 56, and the groove 56b of the high melting point metal 56a.

The first cathode 56 is connected to the first piping 5 attached to the other end of the airtight container 51 via a Kovar ring 59, an alumina porcelain insulating tube 60, and a Kovar ring 61.
It is attached and fixed to a second pipe 62 having a diameter smaller than that of the second pipe 62 .

Further, the second cathode 63 is disposed close to and opposite to the opening surface of one end of the airtight container 51.

The refractory metal 63a on the inner peripheral surface of the second cathode 63 is provided with an opening having a smaller diameter on the upper side of the container i.

The second cathode 63 is attached and fixed to one end of a current lead member 64 passing through the flange 52.

The current lead member 64 has its outer peripheral surface insulated with an alumina porcelain insulating tube or the like, and the flange 5
2 is insulated.

Thus, the second cathode 63 is insulated from the airtight container 51.

According to such a configuration, since the anode 51a has the same potential as the wall surface of the vacuum chamber, etc., by connecting a discharge power source between the wall surface of the vacuum chamber and the flange 58 and the current lead member 64, , a PIG discharge can be generated between the anode 51a and the first and second cathodes 56 and 63.

Then, by irradiating the wall surface of the vacuum chamber with a particle beam by this PIG discharge, the wall surface can be discharge-cleaned.

Therefore, the same effect as the previous embodiment is achieved.

In addition, the pipe 57 and the through hole 56b of the high melting point metal 56a
Since the discharge working gas is supplied into the discharge space through the discharge working gas, contamination of the wall surface to be discharge cleaned by the discharge working gas can be reduced.

Furthermore, the magnetic field generator A housed in the airtight container 511C can generate a half-mirror-shaped magnetic field to effectively guide ions formed by discharge to the outside.

Therefore, the energy efficiency of discharge cleaning can be further improved.

Further, since the wall surface of the airtight container 51 is used as the anode 51a, there is an advantage that there is no need to provide a special anode and the structure can be simplified.

Note that this invention is not limited to the embodiments described above.

For example, the magnetic field generator housed in the airtight container is
Any material may be used as long as it is electrically insulated from the cooling water flowing through the container and has high thermal conductivity with the cooling water.

Furthermore, it goes without saying that the shapes of the anode, cathode, etc. may be adjusted as appropriate depending on the specifications.

Furthermore, each member can be changed as appropriate as long as it is suitable for use in an ultra-high vacuum.

In short, this invention can be implemented with various modifications without departing from its gist.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a schematic structure of an embodiment of the present invention;
FIG. 2 is a sectional view showing a schematic structure of another embodiment. DESCRIPTION OF SYMBOLS 1... Airtight container, (... Magnetic field generator, 5... First cathode, 7... Second cathode, 9... Anode, 41...
...Winding container, 42...Air core electromagnet.

Claims (1)

[Scope of Claims] 1. A magnetic field generating device housed in a vacuum container to be discharge cleaned, forcedly water cooled and energized, and an opening provided inside the magnetic field generating device and penetrating in the magnetic field generation direction of the magnetic field generating device. the anode, and a plurality of cathodes that are spaced apart and opposed to each other at both end openings of the anode, and at least one of which has an opening extending outward from the center of the opening of the anode. . A discharge cleaning device, characterized in that the inner wall surface of the vacuum container is cleaned by irradiating a particle beam generated by the PIG discharge between the anode and the cathode. 2. The magnetic field generator is housed in an airtight container whose outer peripheral surface is suitable for use in an ultra-high vacuum, and is electrically insulated from the cooling water in the airtight container. The discharge cleaning device according to scope 1. 3. The discharge cleaning device according to claim 2, wherein the anode is formed integrally with the wall surface of the airtight container. 4. The discharge cleaning device according to claim 1, wherein the cathode is made of a high melting point metal.