JPS6129156Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetron, and particularly to an output section of a magnetron.

FIG. 1 is a partially sectional view showing a conventional magnetron. In the figure, reference numeral 1 denotes a cylindrical anode, and inside the anode 1 there is provided a plate vane 2 that protrudes toward the center of the anode 1, and the anode 1 and the vane 2 form a resonant cavity. 3 is a cathode located at the center inside the anode 1, and the cathode 3 and the vane 2 form a working space.
Magnetic pole pieces 4 and 5 are airtightly fixed to both ends of the anode 1 by brazing, arcing, etc., and the magnetic pole pieces 4 and 5 serve to concentrate the magnetic flux of an external magnet (not shown) in the working space. . A stem 6 is hermetically fixed to the magnetic pole piece 4 via a sealing metal 7, and the stem 6 supports the cathode 3. Reference numeral 8 denotes a cylindrical output-side insulator fixed to the air window through a reporting metal 9 made of Kovar or the like to the magnetic pole piece 5. The output-side insulator 8 is made of ceramic, glass, or the like. Reference numeral 10 denotes an exhaust pipe made of copper that is hermetically fixed to the upper end of the output side insulator 8, and the exhaust pipe 10 also functions as an output radiation antenna. 11 has one end connected to one of the vanes 2, passes through a hole 12 provided in the magnetic pole piece 5, and has the other end fixed to the exhaust pipe 10.
Antenna conductor wire pressure welded to 13, exhaust pipe 1
The metal cover 13 is a cylindrical metal cover with a bottom that is fitted with the exhaust pipe 10 and the antenna conductor 11. The metal cover 13 protects the welded part of the exhaust pipe 10 and the antenna conductor 11, and the electric field concentrates on the welded part and sparks are generated. It also serves as a high-frequency antenna.

FIG. 2 is a diagram showing details of the portion where the output side insulator 8 is fixed to the sealing metal 9 of the conventional magnetron shown in FIG. 1. As shown in the figure, in order to fix the output side insulator 8 to the sealing metal 9, first sinter Mo on the lower end surface of the output side insulator 8, and then plate it with Ni to form a metallized layer 14. The sealing metal 8 is brazed with a brazing material 15 such as an Ag-Cu alloy or an Au-Cu alloy through the metallized layer 14. In this case, when forming the metallized layer 14 on the lower end face of the output side insulator 8, Mo is sintered and metallized on the lower part of the inner peripheral surface of the output side insulator 8 depending on the surface condition of the output side insulator 8. It may be done. In this case, when a large microwave voltage difference occurs between the relatively large convex portion 14a of the metallized layer 14 formed on the side surface and the antenna conducting wire 11, concentration of the microwave electric field occurs, so the convex portion 14a The surrounding area is locally heated. For this reason, gas may be released and the vacuum inside the magnetron may become defective, or the brazing material 15 may have flowed into the convex portion 14a.
There were problems in that the output side insulator 8 would sputter and the output side insulator 8 would crack.

FIG. 3 is a sectional view showing the output section of the magnetron according to the present invention. In the figure, sealing metal 9
has a protrusion 9a that protrudes further inward than the inner diameter of the output side insulator 8.

In the magnetron configured in this way,
Since the protruding portion 9a of the sealing metal 9 protrudes further inward than the inner diameter of the output side insulator 8, it is close to the antenna conductor 11 and becomes a concentration point of the electric field, so that the metallized layer of the output side insulator 8 14 and its convex portion 14a are electrically shielded, and the concentration of electric field is significantly alleviated. Therefore, even if a large microwave voltage difference occurs between the metallized layer 14 and the antenna conducting wire 11, a portion of the output side insulator 8 will not be locally heated. In this case, since the protrusion 9a of the sealing metal 9 is close to the antenna conducting wire, the microwave electric field tends to concentrate, but the surface of the protrusion 9a can be treated by tumbling, pickling, electrolytic polishing, sandblast, etc. If it is made smooth, the degree of electric field concentration will be reduced, so that the protrusion 9a will not be locally heated.
In addition, even if spatter occurs during the exhaust process or during use, since the protrusion 9a of the sealing metal 9 is present, spatter is less likely to adhere to the output side insulator 8, so the output side insulator 8 heats up significantly. It will not be done. Further, when the length of the protrusion 9a of the sealing metal 9 in the axial direction of the protrusion 14a of the metallized layer 14 (see FIG. 2) is, for example, about 0.2 mm, the protrusion length is desirably several times that length. In experiments, the above-mentioned effect was obtained with a thickness of about 1 mm. Therefore, the protrusion length of the sealing metal may be set depending on the axial length of the protrusion of the metallized layer.

As explained above, in the magnetron according to the present invention, even if a large microwave voltage difference occurs between the metallized layer 14 and the antenna conducting wire 11, local heating does not occur, and the output side insulator 8
Since it does not heat up significantly, there are no gas emissions, sparks, or spatters even during overload operation, and the output side insulation does not crack, resulting in a long life. There is.

In the above embodiment, the exhaust pipe 10 was provided at the upper end of the output side insulator 8, but the exhaust pipe 10 was not provided at the upper end of the output side insulator 8, and the antenna conductor 11 was simply used to maintain airtightness. It goes without saying that the present invention can be applied to a magnetron provided with a metal material for support and provided at any other location on the exhaust pipe. Furthermore, it goes without saying that the present invention can be applied to a magnetron in which the antenna conducting wire 11 is bent and fixed directly to the upper end of the output side insulator 8. In this case, the output side insulator 8 may have a dome shape.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view showing a conventional magnetron, Fig. 2 is a view showing a portion where an output side insulator is fixed to the crimping metal, and Fig. 3 is a cross-sectional view showing the output part of the magnetron according to the present invention. It is a diagram. 1... Anode, 2... Vane, 3... Cathode, 4, 5... Magnetic pole piece, 6... Stem, 7, 9...
... Sealing metal, 8 ... Output side insulator, 10 ... Exhaust pipe, 11 ... Antenna conductor wire, 13 ... Metal cover, 14 ... Metallized layer, 15 ... Brazing material.

Claims (1)

[Scope of utility model registration request] an anode, a plurality of vanes provided in the anode for forming a resonant space, an antenna conducting wire having one end connected to the vane, a sealing fitting welded and fixed to the anode, and a metal fitting attached to the wear metal. In a magnetron having an output-side insulator that is hermetically sealed by brazing through a metallized layer and that surrounds a part of the antenna conductor wire in a cylindrical shape, the output-side insulator and the sealing metal are connected together. A magnetron characterized in that the inner circumferential edge of the sealing metal in the brazing portion itself protrudes further in the radial direction than the inner circumferential edge of the output side insulator.