JPS583337B2 - Magnetronno Seizouhouhou - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing magnetons.

As is well known, the oscillating section of a magnetron has a structure as shown in FIG.

That is, in the figure, numeral 11 is a cylindrical anode body, 12 is a vane, and 13 is a cylindrical anode body.
14 and 15 are output antennas, 14 and 15 are magnetic pole pieces, 16 is a cathode filament, 17 and 18 are end hats, 19 is a cathode stem, 20 and 21 are a pair of supports that support the cathode, and are a center support rod and a cathode support cylinder, respectively. 22 represents an output antenna end cap.

By the way, the getter of the magnetron is sometimes attached to the end hat 17, 1B because it needs to operate in a high temperature state. Especially, immediately after the magnetron starts operating, the electron emission of the cathode filament becomes unstable due to the gas released from the electrode parts, and the power source becomes unstable. In order to prevent abnormal surge voltage from occurring in the circuit and resulting in unstable operation, ring-shaped bulk getters 23 and 24 are attached to the cathode filament 16 side of the end hats 17 and 18, as shown in FIG.

The pair of end hats has an outer diameter that is sufficiently larger than the diameter of the filament, thereby preventing electrons emitted from the filament from escaping in the direction of the magnetic pole pieces.

A magnetron having such a structure has conventionally been assembled as shown in FIGS. 2 to 5.

That is, first, as shown in FIG. 2, a cylindrical part made of molybdenum Mo and having an integrally formed cathode stem side end hat 18 is assembled with a support cylinder 21, and then they are arc welded together as shown by the cross mark and arrow a. stick.

Next, the center support rod 20 is inserted and sealed and fixed together with the magnetic pole piece 15 at the cathode stem portion.

Next, as shown in FIG. 3, a cathode filament 16 made of tungsten W wound into a coil is inserted, and
The other end hat 17 is fitted to the tip of the end hat 17, and the position indicated by the arrow a is arc welded.

Then, the filament and the protrusion that will become the filament connection part of each end hat are soldered with platinum brazing.

This cathode assembly is placed in a carburizing device, and the cathode filament is carbonized.

And finally, zirconium (Zr) as shown in Figure 4.
a horseshoe-shaped bulk getter 23 having a notch 25;
24 is inserted and brought into contact with the filament side surfaces of the end hats 17 and 18 as shown in FIG. 5, and electrical resistance welding is performed as shown by arrow b.

This spot welding is done at several points to prevent peeling.

Such conventional assembly manufacturing methods have the following drawbacks.

In other words, if carbonization is performed with end hats fixed to both sides of the filament, the hydrogen and benzol mixed gas flow for carburizing is blocked by the end hats and tends to be diluted near the ends of the filament. Non-uniformity is likely to occur.

In addition, a carbonized layer is formed on the surface of the end hat, making it brittle.
When welding the getter to this end hat later, we were unable to obtain sufficient welding strength.

This is particularly noticeable in the upper end hat 17 shown fixed to the tip of the center support rod 20, which tends to become hot.

Furthermore, the shape of the getter used is limited to one with a notch as shown in Figure 4, making it impossible to increase the volume of the getter material, and the area around the notch may swell and deform significantly during long-term operation of the magnetron. This tends to cause defects such as discharge and contact between electrodes.

The present invention is a method that improves the drawbacks of the conventional methods as described above, and embodiments thereof will be explained with reference to the drawings.

Note that the same parts as in FIGS. 1 to 5 are given the same reference numerals.

First, as shown in FIG.
The mark and the joint portion indicated by the arrow l1 are fixed by laser welding.

This cylindrical component 21a is formed integrally with the end hat 18 and a filament connecting portion 18a that projects slightly upward.

The support tube 21 and the cylindrical component 21a constitute a first cathode support that supports the filament.

Next, as shown in FIG. 7, the center support rod 20 is coaxially inserted inside the support tube 21 and the cylindrical part 21a, and a stepped filament fixing device with a central hole is inserted at the tip of the support rod 20. The cylindrical block 25 is fitted, and the fitted portion is laser welded as shown by arrow l2.

Of course, this may be formed integrally with the center support rod in advance.

In this way, the center support rod 20 and the cylindrical block 25 are
It constitutes the cathode support.

Then, without fixing the end hat to the second cathode support, insert the tungsten fiber filament 16 from above, and connect the filament connecting portion 18a of the cylindrical part 21a with the first end hunt 18 on the lower side of the figure and the upper side of the cylindrical part 21a. Both ends of the filament are laser welded to the filament connection portion, that is, the cylindrical block 25, as shown by the arrow 13 to electrically connect them.

In addition, the first and second electrodes extending parallel to each other in the cathode stem portion
The cathode support is sealed and fixed, and the magnetic pole piece 15 is also sealed and fixed.

Next, the filament is carbonized in this state. On the other hand, as shown in FIG. 8A, the upper second end hat part 17 is made of ring-shaped zirconium (Zr
) A bulk getter 26 formed of a plate is fixed by laser welding at several locations as indicated by arrow l4.

Next, after carbonizing the filament, as shown in Figure 8, a ring-shaped bulk getter 27 without a notch is inserted into the lower first end hat 18 from the upper end of the filament as shown by the dotted line, and 15《Weld and fix at several points using a laser.

Both getters 26, 27 are therefore attached to the filament side of the end hat.

Then, as shown in FIG. 9, the getter 26 is
The upper second end hat 17 to which is fixed is fitted into the cylindrical block 25 at the tip of the center support rod, and fixed by laser welding as shown by arrow 16.

According to the magnetron manufacturing method of the present invention, the filament can be carbonized uniformly.

In other words, for example, the 10th cathode support is attached with no second end hat attached to the tip of the second cathode support, which is further extended than the tip of the first cathode support with the first end hat. As shown in the figure, a filament structure 32 is installed in a carbonization treatment device 31 such as a Pelger, hydrogen and benzene gas are sealed in from the upper inlet as shown by the arrow 33, and the filament is heated to a high temperature of about 2000°K to form a carburized layer. When generated, the gas spreads even more throughout the filament without being hindered by the absence of the second end hat, and a more uniform carburized layer is formed over the entire filament.

In addition, since the second upper end hat is carbonized without being fixed and the getter is attached, a ring-shaped getter without a notch can be used when welding the getter to either the upper or lower end hat. Since the method of the present invention has fewer restrictions on assembly and manufacturing that exist in the conventional method of carbonizing with both end hats attached and then attaching the getter material, it is possible to use a relatively arbitrary getter shape and sufficient getter In addition to being able to provide volume, there is no problem of significant local swelling or deformation even during long-term operation of the magnetron.

Furthermore, a getter material is fixed in advance to a second end hat that is fixed to the tip of the center support rod that constitutes the second cathode support, and after the filament is carbonized, this end hat is fixed to the center support rod. According to this method, the surface of this second end hat remains clean because no carbide is attached to it, and since this second end hat can be handled as a single unit, the means for fixing the getter or the number of welding points can be adjusted arbitrarily. You can easily fix the getter with ease.

Since the getter fixed to the second end hat, which tends to reach a high temperature during the carbonization process, does not undergo the filament carbonization process, it can be passed through the magnetron manufacturing process in good quality.

Furthermore, after the filament is carbonized, the first cathode support, which has already been fixed to the cathode stem side,
According to the method of fixing the getter material to the end hat, in the same way as described above, a ring-shaped getter without a notch is attached as shown in FIG. This allows for sufficient getter volume to be secured, and also to suppress swelling and deformation during operation.

Also, during the carbonization process, the temperature of the second end hat is maintained at a relatively low temperature due to the heat generated in the support tube, so that a carbonized layer is hardly generated on the surface, and the welding strength is hardly impaired.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing the structure of a magnetron, FIGS. 2 to 5 are views showing conventional assembly methods, FIG. 4 is a perspective view showing a getter, and FIGS. 6 to 9 are views of the present invention. FIG. 10 is a schematic view for explaining the operation and effect of the present invention. 19... Cathode stem, 18... First end hat, 17... Second end hat, 16
...Filament, 21 and 21a...
・・Support cylinder and cylindrical parts constituting the first cathode support,
20 and 25... Central support rod and cylindrical block constituting the second cathode support, 26, 27...
・Getter.

Claims (1)

[Claims] 1 A pair of first and second cathode supports are extended parallel to each other with cathode stems separated, and both ends of a tungsten cathode filament are electrically connected to the tips of each of the cathode supports separated by a predetermined distance. In the method for manufacturing a magnetron in which a pair of first and second end hats are provided at each of these filament connection portions, the filament connection portion of the first cathode support having a first end hat close to the cathode stem; The above-mentioned filament is disposed between the filament connection part of the second cathode support with the second end hat not fixed so as to coaxially surround the second cathode support, and the filament of each support is A step of electrically connecting and fixing the filament ends to the connecting portions, a step of carbonizing the cathode filament after this step, and a step of fixing a second end hat to the second cathode support after this step. A method for manufacturing a magnetron, comprising: