JP3410878B2 - Output structure of magnetron - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output structure of a magnetron used in a radar device.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing an example of an output structure of a conventional vane strap type magnetron. Reference numeral 1 denotes an anode, and a plurality of anode pieces (vanes) extending from the inner circumference of the anode shell 1a toward a cathode (not shown) arranged in the center thereof form a small cavity each of which is a resonator. Normally, adjacent small cavities are formed so as to operate in a π mode having a phase difference of π radian, and in order to stabilize this π mode operation, every other anode piece has the same potential by the strap ring 1c. Are linked together. Two
Is an output antenna, which is formed of a metal such as nickel or copper, has one end formed into a loop in one small cavity 1d, and the tip thereof is brazed to one anode piece 1b. On the other hand, the other end is fitted to the output ceramics 4 via the side wall of the anode shell 1a. Reference numeral 4 is an output ceramics made of alumina or the like, which is brazed and fixed to the end surface of the flange 8 via a brazing material washer 9 so as to cover the hollow portion of the flange 8 communicating with the inside of the anode 1 so as to maintain a vacuum in the anode 1. Has become a vacuum wall. Reference numeral 5 denotes a waveguide, which outputs the microwave radiated from the output antenna 2 through the output ceramics 4 to the outside. Reference numeral 8 denotes a flange, which is a tubular body joined by brazing between the anode 1 and the output ceramics 4 and serves as a vacuum wall like the output ceramics 4. As the operation of this example, the anode 1
The microwave oscillated in 1 is transmitted from the output antenna 2 to the waveguide 5 through the output ceramics 4 and is output from the waveguide 5 to the outside.

[0003]

In the magnetron having the above-mentioned output structure, since the output ceramics and the output antenna are only fixed by fitting, the output antenna vibrates when an external vibration is applied, and the oscillation frequency. There was a problem that the output power fluctuates due to the influence of vibration. When metalizing the output ceramics and brazing the output antenna so that the output antenna does not vibrate due to external vibrations, both ends of the output antenna will be completely fixed by brazing. When the temperature rises in the exhaust process or the exhaust process, the output antenna may be deformed or broken in the middle due to the difference in thermal expansion coefficient between the metal output antenna and the ceramics. Further, if the dimensional tolerances of the output ceramics and the output antenna are made strict and the fitting is made tight in order to suppress the vibration, the unit price of the parts is significantly increased, and the fitting between the output antenna 2 and the output ceramic 4 becomes strict. Therefore, assembly becomes difficult. Further, since the output antenna fits closely to the inner diameter of the output ceramic, the output ceramic is cracked due to the difference in the coefficient of thermal expansion when the temperature rises in the evacuation process or the like. It is also possible to add elasticity to the output antenna by slitting or bending it, and press the output antenna against the output ceramics with the force of the spring to fix it, but when brazing the output antenna When the temperature rises in the exhaust process or the exhaust process, the metal loses the spring property due to the creep phenomenon, and therefore it is impossible to reliably fix the metal even by this method. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a stable magnetron in which fluctuations in oscillation frequency and output power are small with respect to vibration and shock during operation.

[0004]

In order to achieve the above object, the present invention is characterized in that the output ceramics and the anode are hermetically bonded to each other via a hollow cylindrical body fixed to the anode shell and communicating with the inside of the anode. In the output structure of the magnetron, one end of which is joined to the anode piece in the anode, the other end of which penetrates through the hollow portion of the tubular body and the other end of which is fitted to the output ceramics is provided. A metal material having a melting point lower than that of the metal of the output antenna filled in the fitting gap with the output antenna, the metal material is not fixed to the output ceramics, but is fixed to the output antennas, and The output antenna is fitted in a sliding state. Further, a fitting gap between the output antenna and the output ceramic may be 0.03 mm to 0.2 mm. Further, the amount of the metal material is 50% to 10% of the total volume of the space formed by the fitting gap between the output antenna and the output ceramics.
It may be 0%. The present invention is, for example, 0.03 at room temperature so that an appropriate fitting gap is formed between the output antenna and the output ceramics at high temperature during brazing.
After the fitting gap of mm to 0.2 mm is provided, the output antenna is fixed by pouring a metal material having a lower melting point than the output antenna into the fitting gap to solidify.

With this configuration, when heat is applied to the output antenna, the output antenna is not fixed to the output ceramics, so that external force as a reaction due to thermal expansion is not applied. In addition, since a metal material is embedded in the fitting gap between the output antenna and the output ceramics,
There is no space for the output antenna to shake even when vibration is applied from the outside.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing an output structure of a magnetron according to the present invention, and the same reference numerals as those in FIG. 3 denote the same or corresponding ones. In the figure, reference numeral 3 denotes a brazing material that has flowed into the fitting gap between the output antenna and the output ceramics and solidified. With this configuration, the output antenna 2 is securely fixed, so that the output power and the oscillation frequency do not change even when external vibration or shock is applied. The operation of the present invention is similar to that of the conventional example. FIG. 2 is an enlarged view of the output antenna and the output ceramics in the output structure shown in FIG. In FIG. 2 as well, the same reference numerals as those in FIG. 1 indicate the same or corresponding ones.

To assemble the output structure of the magnetron according to the present invention, first, the output antenna 2 is fixed to the anode piece 1b by caulking or the like, and a brazing material is placed there (not shown). Next, the output antenna 2 is provided with 6 or 7 shown in FIG.
At this position, the brazing material is assembled, the parts such as the output ceramics 4, the flange 8 and the like are assembled, the brazing material is placed at each joint, placed in a hydrogen furnace, etc. .

At the location before the melting of the brazing material embedded in the fitting gap between the output antenna 2 and the output ceramics 4,
Whether to select the location of reference numeral 6 or 7 is selected depending on the direction of the output antenna at the time of brazing. That is, the brazing material flows due to gravity and the output antenna 2
It is advisable to make a selection such that the fitting gap between the output ceramics 4 and the output ceramics 4 is entered. When the output antenna is a nickel round bar with a diameter of 1.7 mm, the output ceramic is alumina, and the brazing material is a brazing material containing silver as a main component, the brazing is performed by heating at 850 ° C. for 15 minutes in a hydrogen furnace and brazing. Good results could be obtained when the gap was 0.03 mm to 0.2 mm. 0.03 mm to 0.2 mm is the difference between the diameter of the output antenna and the diameter of the hole of the output ceramic to which it is fitted. In addition, the reason for being 0.03 mm to 0.2 mm is that the brazing material does not enter the fitting gap when it is narrower than 0.03 mm, and when it exceeds 0.2 mm, the brazing filler metal is not in the portion other than the fitting gap. This is because the brazing filler metal may run off. Further, the amount of brazing material should be appropriately selected through experiments and the like, but the suitable amount experimentally determined in the completion process of the present invention is formed by the fitting gap between the output antenna and the output ceramics. 50% to 100% of the total volume of the space
Is.

Output ceramics 4 due to the difference in coefficient of thermal expansion
In order to prevent the destruction of the output ceramics, it is sufficient to allow the output ceramics 4 and the output antenna 2 to have a proper fit.
However, this cannot reliably fix the output antenna. Therefore, in the present invention, as shown in FIG. 2, the fitting gap is set to 0.03 mm to 0.2 mm, and the brazing material is placed at the position of 6 or 7 and assembled. Then,
At the time of brazing, these brazing materials flow into the fitting gap to fix the output antenna. Moreover, in this example, the slight difference in coefficient of thermal expansion between the brazing material and the output ceramics 4 can be utilized to form an appropriate gap without fail, so that the output ceramics will crack when the temperature rises. No trouble occurs. That is, at the time of brazing at a high temperature, the brazing material flows between the output ceramics 4 and the output antenna 2 (for example, nickel) so as to fill the fitting gap exactly. The expansion coefficient is 15 to 20 × 10 ⁻⁶ / ° C.,
Since it is larger than 7 to 8 × 10 ^-6 / ° C of ceramics, when the temperature decreases and the shrinkage occurs, the brazing material and the output antenna shrink more greatly than the output ceramics, and the output antenna 2 and the output antenna must be output. A very small gap is generated between the ceramics 4. Furthermore, output ceramics 4
Since no metallization is applied to the output antenna 2, the output antenna 2 is not completely adhered to the output ceramics 4. Therefore, even if the output antenna 2 expands due to a temperature rise, the output antenna 2 may expand without receiving an external force. it can. Therefore, the output antenna 2 is not deformed or broken unlike when the output antenna 2 and the output ceramics 4 are brazed and fixed.

Although the above description has been made in consideration of the magnetron, it is easily inferred that the electron tube having the same output shape can be applied to the cross field amplifier (CFA) and the TWT. .
Further, in the above description, the brazing material is filled in the fitting gap between the output antenna and the output ceramics, but another metal material instead of the brazing material may be used. However, for convenience of manufacturing, the metal material is
It has a lower melting point than the metal of the output antenna. The table below shows the results of comparison of the oscillation frequency and the rate of change in output power in the vibration test between the conventional magnetron shown in the conventional example and the magnetron according to the present invention. In addition,
Both have a mating gap of 0.1 mm and an output antenna diameter of 1.7.
In the vibration test, a sine wave of up to 3 G was applied at a frequency of 20 to 200 Hz. As shown in the table below, in the magnetron according to the present invention, the change rate of the oscillation frequency by the vibration test is 1/8 of the conventional one,
The rate of change in output power by the vibration test was reduced to 1/10.

[0011]

[Table 1]

[0012]

As described above, since the metal material is embedded in the fitting gap, the output antenna can be reliably fixed to the output ceramics, and even if external vibration is applied, The output antenna will not vibrate. Further, since the output antenna is not completely fixed to the output ceramics, even if the output antenna expands due to temperature rise, the output antenna can be extended without receiving external force. Therefore, the output antenna is not deformed or broken. In general, it is possible to provide a stable magnetron with no change in oscillation frequency or output power.

[Brief description of drawings]

FIG. 1 is a sectional view showing an outline of an output structure of a magnetron of the present invention.

FIG. 2 is an enlarged view of an output antenna portion of the output structure of the magnetron shown in FIG.

FIG. 3 is a sectional view showing an outline of an example of an output structure of a conventional magnetron.

[Explanation of symbols] 1 anode 2 output antenna 3 brazing material 4 output ceramics 5 Waveguide 6, 7 Brazing material mounting position 8 flange 9 wax washer

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01J 23/40

Claims (2)

(57) [Claims] 1. An output ceramic and an anode are airtightly bonded to each other through a hollow cylindrical body that is fixed to an anode shell and communicates with the inside of the anode, and one end of the output ceramics and the anode are bonded to the anode piece. In a magnetron output structure having a metal output antenna that penetrates through a hollow part of a body and has the other end fitted to the output ceramics, the output antenna buried in a fitting gap between the output ceramics and the output antenna. Has a metal material with a melting point lower than that of
An output structure of a magnetron, wherein the metal material is not fixed to the output ceramics but fixed to the output antenna, and the ceramics and the output antenna are fitted in a sliding state. 2. The magnetron output structure according to claim 1, wherein a fitting gap between the output antenna and the output ceramics is 0.03 mm to 0.2 mm.