JPH0610959B2 - Magnetron - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetron.

[Conventional technology]

FIG. 3 shows an example of a conventional magnetron. Both ends of the filament 1 are supported by filament supports 4 and 5 through end shields 2 and 3, and the magnetron supports 4 and 5 form a vacuum container. It penetrates the insulator 6 and is brazed to the insulator 6 via a metal washer 7. Further, around the filament 1, an anode composed of a plurality of vanes 8 arranged radially and an anode cylinder 9 holding them is arranged. The vanes 8 are electrically connected to each other by strap rings 10 and 11. An output conductor 12 is connected to one of the vanes 8 so that the microwave energy generated in the working space is radiated to the load circuit through the output radiation window 13. Magnetic poles 14 and 15 for supplying a focusing magnetic field to the working space are fixed to the upper and lower ends of the anode cylinder 9,
Further, the magnetic poles 14 and 15 are brazed and sealed to the output radiation window 13 and the insulator 6 via the rings 16 and 17, respectively, to form a vacuum container.

The conventional example as described above is disclosed in, for example, JP-A-53-90752.
Etc.

By the way, the filament 1 is made of tungsten containing thorium whose surface layer is carbonized because stable electron emission is easily obtained, and the operating temperature is 1700 to 18
It is a high temperature of 00 ° C. Therefore, the end shields 2 and 3 that support the filament 1 and the filament supports 4 and 5 also need to be made of a material that can be used at high temperatures, and molybdenum (Mo) is generally used.
Further, since it is difficult to braze the filament supports 4 and 5 made of Mo to the insulator 6 made of ceramic with high reliability, the metal washer 7 has a Kovar (cobalt) expansion coefficient close to that of the ceramic insulator. F
e-Ni-Co alloy) is used.

[Problems to be Solved by the Invention]

Thus, since the filament supports 4 and 5 are formed to penetrate the insulator 6 for a long time, a large amount of expensive refractory metal such as Mo is required. Further, Mo has poor wettability with silver brazing, making it difficult to braze with high reliability. Further, since Mo is a brittle material, defects are likely to occur on the surface and inside when it is processed into a rod shape or a linear shape. If the filament supports 4 and 5 penetrate inside and outside the vacuum container as described above, the defects cause a vacuum. Easy to leak. Further, the metal washer 7 must use an expensive and uncommon metal such as Fe-Ni-Co. Furthermore, since the insulator 6 and the washer 7, and the washer 7 and the filament supports 4 and 5 are brazed to each other, a large amount of expensive silver brazing material is required, and the sealing structure becomes complicated and a vacuum leak occurs. It has various drawbacks such as being easy.

Another problem of the prior art is that the ring 17 forming the metal envelope, the sealing surface with the insulator 6, and the sealing surface with the filament support 4 and the insulator are different from each other. Therefore, there is a problem in that the step of performing pretreatment for sealing on the insulator becomes complicated and the manufacturing cost increases.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide an economical and highly reliable magnetron.

[Means for Solving the Problems]

In order to improve the reliability of the sealing portion between the filament supports 4 and 5 and the insulator 6, which is the first problem, the auxiliary sealing material is used to connect to the filament, and the auxiliary sealing material The problem can be solved by sealing the insulator 6.

Since the sealing surface is formed on both sides of the insulator 6, which is the second problem, the pretreatment for sealing the metal with the insulator must be performed on both sides of the insulator. The problem can be solved by forming the filament support or the sealing surface between the auxiliary sealing body and the insulator inside the vacuum container.

[Action]

Since the auxiliary sealing body used for solving the first problem is not limited to the heat-resistant metal material, a material having a good sealing property with the insulator can be selected, so that the reliability of the sealing section can be improved. it can.

By using the above means for solving the second problem, the sealing surface between the filament support or the auxiliary sealing body and the insulator is sealed with the metal constituting the vacuum envelope and the insulator. It can be formed on the same side as the landing surface.

Hereinafter, the present invention will be described with reference to the illustrated embodiments.

〔Example〕

In order to solve the above problems, a cross-sectional view of a magnetron devised by the present inventor is shown in FIG. The same members in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. The filament supports 20 and 21 are formed to have a short length that does not penetrate the ceramic insulator 6.
An auxiliary sealing body 22 made of an Fe material penetrating the insulator 6 is fixed to the end portion of 21 by plasma welding, butting resistance welding or the like. The auxiliary sealing body 22 has a flange portion 22a.
Is formed on the flange portion 22a.
A cup-shaped portion 22b having a thin surface having a surface of about 0.4 mm is formed by integral plastic working. The tip of the cup-shaped portion 22b is brazed to the metallized alumina ceramic insulator 6.

Now, although the operating temperature of the filament 1 is high, the filament supports 20 and 21 have a temperature gradient that decreases toward the outside of the tube, and since the temperature in the vicinity of the insulator 6 is sufficiently low, the auxiliary sealing is performed. As the material of the body 22, a metal having a low melting point such as Fe can be used. Although the expansion coefficient of the ceramic insulator 6 is different from that of the auxiliary sealing body 22 made of Fe, the sealing portion of the auxiliary sealing body 22 has a thin cup-shaped portion 2
By adopting 2b, stress relaxation due to plasticity can be performed.

As described above, since the filament supports 20 and 21 have a short length that does not penetrate the insulator 6, it is possible to reduce the amount of expensive refractory metal such as Mo used. Further, since the auxiliary sealing body 22 is made of inexpensive iron, it can be integrally processed into a shape that is easily plastically worked and easily sealed, and the expensive and high melting point washer 7 in FIG. Further, the malleability is superior to that of Mo, and the surface and the inside are free from defects during processing, and the reliability of vacuum sealing is improved. Also filament support 20,
Since the 21 and the auxiliary sealing body 22 can be fixed to each other by welding or the like, the work is easy and an expensive brazing material is not required.

However, in the above structure, since the brazing surfaces are provided on both sides of the insulator 6, the pretreatment process is increased.

FIG. 2 is a cross-sectional view of essential parts showing an embodiment of the magnetron according to the present invention. In FIG. 1, the auxiliary sealing body 22 is sealed on the outside of the insulator 6, but in this embodiment, the auxiliary sealing body 22 is sealed on the inside. In this way, the auxiliary sealing body 22 and the ring 17 are
It becomes possible to seal and on the same side with respect to the insulator 6. Therefore, the pretreatment process for sealing the insulator 6 and the metal, which is performed on the insulator 6, can be simplified. In addition, as shown in FIG.
If the ring 17 and the ring 17 are made of an insulating material and their brazing surfaces are formed on the same plane, the pretreatment step can be further simplified.

Although the above description has been made on the assumption that the auxiliary sealing body and the insulating material are sealed, the same effect can be obtained when the filament support and the insulating material are sealed as in the conventional case without using the auxiliary sealing material. Of course, you have.

In the above embodiment, the material of the auxiliary sealing body 22 is F
Although the case of e has been described, it is not particularly limited as long as it is a metal having a melting point lower than that of Mo and can withstand the temperature around the insulator 6, and may be, for example, a Fe—Ni alloy. If the expansion coefficient between the auxiliary sealing body 22 and the insulator 6 is large, the thin cup-shaped portion 22b is formed on the auxiliary sealing body 22 as described above.
However, when the Fe-Ni alloy is used for the auxiliary sealing body 22, the cup-shaped portion 22b is not provided and only the flat flange portion 22a is formed. The part 22a may be sealed. Further, in the above embodiment, the filament support 2 is formed by connecting the filament 1 through the engine shields 2 and 3.
Although it was supported by 0 and 21, the tip end of the filament support may be bent and the filament may be directly supported by this bent portion.

〔The invention's effect〕

According to the present invention, it is possible to manufacture a magnetron with a highly reliable sealing portion and a low manufacturing cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the magnetron according to the present invention, FIG. 2 is a sectional view showing a main portion of another embodiment of the magnetron according to the present invention, and FIG. 3 is a sectional view of a conventional magnetron. is there. 1 ... Filament, 2, 3 ... End shield, 6 ...
... Insulator, 17 ... Ring, 20, 21 ... Filament support, 22 ... Auxiliary sealing body, 22a ... Flange portion, 22b ... Cup-shaped portion.

Claims (1)

[Claims] 1. A vacuum container is composed of at least a ring and an insulating material, the insulating material and the ring are sealed at a first sealing surface, and both ends of a filament constituting a cathode are end shielded. In a magnetron supported by a filament support made of Mo material through the filament support, the filament support has its end portion in the vacuum container, and is separated from the insulator by an auxiliary sealing body made of Fe material. The auxiliary sealing body has one end that penetrates the insulator to reach the outside of the vacuum container and the other end that is inside the vacuum container and that is connected to the insulator. 2 has a thin cup-shaped flange extending on the sealing surface, and further has the first sealing surface and the second sealing surface.
The sealing surface of the magnetron is formed in the vacuum container on the same side of the insulator and on the same plane as the insulator.