JPS6131185B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a magnetic field discharge device in which crossed field discharge is performed.

Background technology and its problems In recent years, efforts have been made to generate and confine high-temperature, high-density plasma in order to realize nuclear fusion. Magnetic field confinement devices are seen as promising as nuclear fusion devices, but one problem that must be urgently solved with these devices is the need to suppress impurities supplied to the plasma. In recent years, it has been found that when the first wall of a tokamak is vapor-deposited with titanium, impurity supply is significantly suppressed. Titanium deposition is performed by heating and vaporizing titanium when the tokamak discharge is stopped.

When titanium is vapor-deposited over a long period of time, there is a problem that the titanium film peels off from the object on which it is deposited, and in nuclear fusion devices, the peeled-off titanium mixes with the plasma and becomes an impurity. Therefore, it has been desired to develop a method and apparatus for forming a titanium film that is stronger than a vapor-deposited film formed by heating and evaporating titanium.

On the other hand, regarding plasma impurities in nuclear fusion devices, atomic ions with large atomic weights have a significant negative effect, while atomic ions with small atomic weights have a lower degree of negative effect, so a method of coating the wall surface with a substance with small atomic weight has been proposed. It was hoped that a proposed and practical device would emerge.

Purpose of the Invention The present invention was made in view of the above circumstances, and its first purpose is to provide an apparatus that can form a strong film with good adhesion on the surface of an object to be coated. providing the configuration;
The second object is to provide an apparatus configuration that can coat a wall surface even with a substance having a very low vapor pressure.

Summary of the Invention By arranging positive and negative poles in a magnetic field, a cross-field discharge of low working gas pressure and high electric pressure is generated and maintained, and high-energy ions generated by the cross-field discharge are efficiently generated. The sputtered atoms are guided to the outside of the discharge device through a gap provided to the anode so as not to impair the stability of the discharge. A shielding body is provided to prevent insulation defects from being contaminated by sputtered atoms, and the crossed field discharge device is detachable from the vacuum vessel, allowing sputtering coating to be applied to the walls of the vacuum vessel, and preventing sputtering. During the period when you are not using it, you can move it to a designated location.
Achieved the purpose.

Embodiment of the Invention FIGS. 1 and 2 are an external view and a sectional view of a magnetic field discharge device showing an embodiment of the present invention. In the cross-sectional view of FIG. 1, the portions of the electrically conductive path that are insulated from the vacuum chamber by an insulating member and that penetrate the wall of the vacuum chamber are shown as cross-sections of the respective portions showing their respective configurations, and the other portions are shown as cross-sections of the respective portions. In the outline drawing of the figure, chain line A-A
The figure shows a cross section along the plane indicated by .

Reference numeral 1a designates two anode end members, and eight blade bodies 1b are fixed between them, and the two anode end members 1a and the eight blade bodies 1b together cover 1 of the external surface area of the tube wall. A tube having a gap of 2/2 or more is formed, and the tube is used as the anode 1. Reference numeral 2a denotes two plate-shaped end hats, which constitute the cathode 2 together with a center electrode 2b fixed between the end hats 2a. The end hats 2a constituting the cathode 2 are disposed close to and covering both open ends of the tube, which is the anode 1, respectively. When a discharge is caused, the axis of the tube of the anode 1 is parallel to the direction of the magnetic field. When a predetermined voltage is applied between the anode 1 and the cathode 2 while a magnetic field is applied, a magnetron discharge is generated and maintained at the portion formed by the inner surface of the tube of the anode 1 and the anode side surface of the cathode 2. Ru.

Reference numeral 3 denotes four anode supports that also serve as power supply paths, and are fixed to two frames 4 that also serve as power supply paths and are fixed to the end members 1a of each anode. 5 serves as a power supply path 4
The main cathode supports are fixed to a frame 7 which also serves as two power feeding paths and which are fixed to two of each of the four pillars 6 which also serve as power feeding paths, two of which are fixed to each end hat 2a.

Reference numeral 8 denotes eight hollow cylindrical insulating members, each of which has connection fittings 9 and 10 fixed to both open ends thereof in an airtight manner and insulated from each other.
It is hermetically connected to a flange 11 at the same potential as a vacuum vessel (not shown) which is normally used at ground potential. 1
2 is a bellows, one end of which is hermetically connected to the flange 11. A flange 13 is used while being airtightly connected to a flange of a vacuum container (not shown) in which the magnetic field discharge device of the present invention is used. Reference numeral 14 denotes a tube, and the tube 14 and the bellows 12 are hermetically connected to each other by a member not shown at a portion not shown. Reference numeral 15 denotes a rod for moving the flange 11 between predetermined positions relative to the flange 13 and for fixedly supporting the flange 11. A shield 16 is attached to each of the pillars 3 and 5, and the pillars 3 and 5 pass through the shield 16 in an airtight manner, and the pillar 3 is kept insulated from the flange 11 so that its vacuum is maintained. A terminal 17 is formed on the outer side of the flange 11 to connect to the power supply cable, and the support column 5 has a terminal 18 formed on the side outside the vacuum of the flange 11 to be connected to the power supply cable. All the shields 16 are hermetically fixed to the connecting fittings 10 facing each other. In this way, the anode 1 and the cathode 2 are supported in a variable position with respect to the vacuum container (not shown) that houses them without changing their mutual positional relationship, and in this embodiment, the anode 1 and the cathode 2 are both insulating members 8
A core flange 1 which is insulated with respect to the vacuum vessel (not shown) and forms a part of the vacuum vessel wall.
It has a power supply path that passes through 1. All of the shields 16 are connected to the inner surface of the tube, which is the anode 1, and the anode of the cathode 2, from all points on the vacuum side surface of the nuclear insulating member 8, each of which is fixed via the connection fitting 10. It is made in such a shape and size that the portion formed by the shaped surface cannot be seen through, and is disposed between the insulating member 8 and the anode 1 and the nuclear cathode 2.

The operation of the present invention will be explained with reference to the embodiments shown in FIGS. 1 and 2. Although the present invention does not limit the type of vacuum vessel used, Taking a type of tokamak as an example, the effect of coating the first wall facing the plasma of the tokamak will be explained. Only a toroidal magnetic field is generated without tokamak discharge. Since the length of the tube of the anode 1 is sufficiently small compared to the large radius of the tokamak, the axis of the tube can be substantially parallel to the toroidal magnetic field, and it is used with such arrangement. . The strength of the magnetic field may be smaller than that in a tokamak discharge, e.g.
0.5 Tesla is fine. When a high voltage is applied between the nuclear anode and the cathode, a magnetron discharge is generated in a portion formed by the inner surface of the tube, which is the nuclear anode 1, and the anode side surface of the nuclear cathode, and is self-sustaining. The voltage between the anode and cathode may be determined depending on the type and pressure of the gas near the electrodes and the type of substance used for coating, and may be, for example, 10 kV.

The surface of the central electrode 2b of the nuclear cathode 2 is formed of a material to be coated, such as titanium, and ions generated by magnetron discharge collide with the nuclear central electrode 2b with high energy, coating the surface material such as titanium. Splash efficiently. A large portion of the sputtered material passes through the gap in the nuclear anode 1 and is ejected to the outside of the nuclear anode 1, and is deposited on a solid surface around the anode 1 and the cathode 2, such as the first wall of a tokamak. , a coating of a nuclear sputtered material, for example titanium, is applied. As is well known, a coating made of a material sputtered by magnetron discharge forms a strong film with better adhesion than that made by vapor deposition. This is the first effect of the present invention, which is the first objective of the present invention, which is that a strong film with good adhesion can be formed on the surface of the object to be coated. In the present invention, since the coating is performed by sputtering, the second objective of the present invention, which is to be able to coat the wall surface even with a substance having a very low vapor pressure, is achieved.

Note that the cathode does not need to have a center electrode. The discharge in this case is a PIG discharge, and an effect similar to the first magnetron discharge can be obtained.

Effects of the Invention The present invention is designed to perform so-called in-situ coating, and the anode and the cathode can be moved in position with respect to the vacuum container housing them without changing their mutual positional relationship. When the magnetic field discharge device of the present invention is not in use, for example after the coating of the first wall of the tokamak is completed, it can be moved to another location for storage, etc. By storing it behind the first wall, it does not interfere with tokamak discharge. Furthermore, the shield prevents the vacuum side surface of the insulating member from being contaminated with sputtered substances and causing insulation defects, so the present magnetic field discharge device can be used for a long period of time.

[Brief explanation of the drawing]

FIGS. 1 and 2 are an external view and a sectional view of a magnetic field discharge device showing an embodiment of the present invention. 1...Anode, 1a...Anode end member, 1b...Blade body, 2...Cathode, 2a...End hat, 2b...
...Central electrode, 3, 5, 6... Support that also serves as a power feeding path, 4, 7... Frame that also serves as a power feeding path, 8... Insulating member, 9, 10... Connection fittings, 11, 13...
Flange, 12...Bellows, 14...Pipe, 15
... Rod, 16 ... Shielding body, 17, 18 ... Terminal.

Claims (1)

[Scope of Claims] 1. A vacuum vessel that is detachably attached to the vacuum vessel in order to cause cross-field discharge to occur in the vacuum vessel where a magnetic field exists, including a base that is detachable from the vacuum vessel, and an insulating base on the base. A discharge section is constructed by installing a support that also serves as a power supply path and is installed through a member, and an anode and a cathode that perform the cross-field discharge on this support. visible from all positions on the surface facing the vacuum side,
A magnetic field discharge device, further comprising: a shield provided apart from other members and provided between the insulating member and the discharge section. 2 Claim 1, characterized in that the surface of the anode is configured with a void of 1/2 or more.
The magnetic field discharge device described in Section 1. 3. The magnetic field discharge device according to claim 1, wherein the anode is cylindrical, and a center electrode is provided at the center of the axis of the cylindrical anode.