JPS5854466B2 - Magnetic field discharge device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a magnetic field discharge device.

The conventional configuration and problems of a crossed field discharge device, which is one type of magnetic field discharge device, will be described using a PIG discharge device, which is one type of crossed field discharge device, as an example.

FIG. 1 is a longitudinal sectional view of a conventional PIG discharge device, in which numeral 1 denotes an anode and has a cylindrical hollow portion 2. As shown in FIG.

Reference numeral 3 designates a set of two plate-shaped cathodes that are disposed close to and apart from each of the open ends of the anode 1.

4 is a tube that is part of a vacuum container that houses the anode 1 and the cathode 3; the anode 1 is held in the tube 4 and electrically connected to the flange 5 through the tube 4 and the flange 5; Connected to the vacuum vessel of the vacuum device and grounded.

Reference numeral 6 denotes a conductor column insulated from the outside, which fixes the two cathodes together and electrically connects them.

7 is a conductor column, one of which is fixed to the power supply terminal 8;
Others are fixed to the insulating support member 9.

The other end of each conductor column 7 is fixed to one of the cathodes 3 to hold the cathode 3, and the power supply terminal 8 and the conductor column 7 fixed thereto form a power supply path to the cathode 3, not shown. The negative high voltage output of the power supply is applied to the feed terminal 8 and the cathode 3
A voltage is applied between the anode 1 and the anode 1.

A magnet 10 applies a magnetic field substantially parallel to the axis of the hollow part 2 of the anode.

The PIG discharge device configured as described above is used as an ion pump, a vacuum gauge pressure sensitive section, etc., but a common problem with these devices is deformation of the anode hollow portion due to sputtering of the cathode material.

To explain this based on FIG. 2 which explains the PIG discharge state, a group of electrons is generated in the hollow part 2 of the anode due to the magnetic field indicated by arrow B and the potential difference given between the anode 1 and the cathode 3 by the DC power supply 13. is captured and the discharge is maintained.

Molecules that fly into the discharge space formed in the hollow part 2 of the anode are ionized by the electrons of the electron group, forming an ion stream I, which impacts the cathode 3 and sputters the cathode material, creating a sputtered atomic stream. produces S.

The sputtered atoms collide with the surface of the cathode 3 or the inner surface of the anode 1 and are captured, and the molecules adsorbed on the captured surface are embedded and deposited to form a deposited layer C.

As the discharge progresses, the thickness of the deposited layer C increases, and the hollow part 2 of the anode shrinks and deforms.

The shrinkage of the hollow part 2 of the anode has the negative effect of changing the electric field in the discharge space and changing the discharge state from the desired one, and the thickened deposited layer is bombarded by electrons in the discharge space and detached. Interaction with isoelectronic groups also has the adverse effect of making the discharge unstable.

The present invention has been made in order to improve the above-mentioned conventional drawbacks, and aims to provide a cross-field discharge device in which changes in discharge conditions and discharge instability caused by the formation of a deposited layer are suppressed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A PIG discharge device which is an embodiment of the present invention will be described below based on the drawings.

3 is a front sectional view, and FIG. 4 is a sectional view taken along the line L--L in FIG. 3, in which the same parts as in FIG. 1 are given the same numbers.

The anode 1 includes a tubular base body 11 having a hollow portion passing through it, twelve wing pieces 12 that are fixed to the base body 11 and extend toward the axis of the hollow portion of the base body and do not contact each other, and the wings. Piece 1
The connecting member 14 electrically connects all of the different wing pieces to a part on a surface that connects the parts of the surface closest to the axis of the hollow part of each of the two base bodies 11.

A pair of plate-shaped cathodes 3 are disposed close to and apart from each of the open ends of the anode 1.

Reference numeral 15 is a conductor column that fixes the two cathodes 3 to each other and electrically connects them. An insulating layer is formed on the outside of the conductor column, and the shielding plate 15a protects the protective layer.

Reference numeral 16 is a conductor column that supports the cathode 3 and forms a power supply path for feeding power to the cathode 3, so that a voltage can be applied between the anode 1 and the cathode 3.

A magnet 10 generates a magnetic field substantially parallel to the axis of the hollow part 2 formed by the anode 1.

Next, the operation of the above device will be explained.

When the voltage between anode and cathode and the strength of the magnetic field are appropriate, the connecting member 14
The lines of magnetic force that intersect with the inner surfaces of the two cathodes 3 and the surfaces of the two cathodes 3 on the anode 1 side form a cylinder, and the electron group that maintains the discharge exists only within the cylinder.

Electrons that enter between adjacent blades 12 collide with the connecting member 14 along the magnetic field and are absorbed, so they are surrounded in three directions by the blades 12 and the base 11, and the other direction is surrounded by the hollow of the anode. No discharge is generated in the space facing the cylinder of part 2.

Gas molecules are ionized by the electrons of the electron group existing within the cylinder, and the generated ions collide with either of the two cathodes 3.

A part of the cathode material sputtered by ion bombardment collides with the facing cathode surface and is captured, and the remaining part of the sputtered cathode material collides with the surface of the anode 1 and is captured and deposited, forming a deposited layer. Form.

Due to the configuration of the anode of the present invention, the capture of cathode material is achieved by the substrate 11.
, the side surface of the blade 12 and the end surface facing the axis of the hollow section 2 of the anode, the side surface of the connecting member 14 and the inner cylinder facing the axis of the hollow section 2 of the anode.

As is clear from the above configuration, most of the cathode material is captured on the inner surface of the base 11 and the side surfaces of the blades 12 that are not in contact with the electron group that maintains the discharge.

Therefore, the interaction between the electron group and the deposited layer is significantly suppressed, and the effect of suppressing the occurrence of discharge instability due to the interaction is obtained.

Furthermore, some of the cathode material deposited on the end surfaces of the blades 12 and the inner surface of the connecting member 14 is re-emitted into space by the electron group.
Since most of the re-emitted material is captured on the inner surface of the anode substrate 11 or on the side surfaces of the winglets 12,
The deposition of the cathode material on the end face of the connecting member 14 and the inner surface of the connecting member 14 can be suppressed, and changes in the discharge state due to the formation of a deposited layer can be suppressed.

As described above, the connecting member 14 has the effect of suppressing the occurrence of parasitic discharge in the space surrounded on three sides by the wing pieces 12 and the base body 11.

This effect may not be achieved with the connecting member 14 shown in the figure, depending on the voltage between the anode and cathode and the strength of the magnetic field.

In that case, the connecting member 14 can have a portion that substantially completely covers the space created by the blades and the base in a plane perpendicular to the axis of the anode, thereby suppressing the generation of parasitic discharge. .

Note that the present invention is not limited to the PIG discharge device shown in the figure, but is also applicable to other types of crossed field discharge devices.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of a conventional PIG discharge device, and Figure 2 is a PIG discharge device.
FIG. 3 is a cross-sectional view of a PIG discharge device showing an embodiment of the present invention, and FIG. 4 is a diagram for explaining the IG discharge state.
It is a sectional view taken along the L line. 1... Anode, 2... Hollow part of the anode, 3
...Cathode, 11...Substrate, 12...
... Wing piece, 14 ... Connection member, 15.16.
...Conductor column, B...Magnetic field, ■...
- Ion flow, S... Atomic flow, C... Deposition layer, 10... Magnet, 13... DC power supply.

Claims (1)

[Claims] 1. A base body having a penetrating hollow part, a plurality of wing pieces fixed to the base body, extending toward the axis of the hollow part of the base body and not in contact with each other, and a hollow part of each of the wing pieces of the base body. an anode comprising a connecting member that electrically connects different blades on at least a portion of a surface connecting the surface portions closest to the axis of the anode; a cathode having a set of two plate-shaped parts disposed close to each other; a means for applying a voltage between the anode and the cathode; 1. A magnetic field discharge device comprising means for generating a magnetic field.