JP3503595B2 - Output window and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a traveling wave tube,
It relates to an electron tube such as a klystron, or an output window provided between a vacuum section and an external waveguide or a device in a device such as a heating device or an accelerating tube that uses electric power of microwave or millimeter wave of these electron tubes. .

[0002]

Electron tubes such as traveling-wave tubes, klystrons or gyrotrons, gyro-klystrons are
An electron gun that emits an electron beam, a collector that supplements the electron beam, and a microwave amplification unit that amplifies microwaves (the same applies to millimeter waves and high frequencies; the same applies to millimeter waves and high frequencies below) due to interaction with the electron beam. , An input / output coupling section which is a connection section between the microwave amplification section and the external waveguide. In this input / output coupling section, an output window is used for maintaining the airtightness inside the electron tube and for transmitting the microwave without loss. In order to transmit the microwave without reflecting it, the impedance matching of the output window needs to be taken. Figure 9
Is a conventional general output window described in, for example, Japanese Patent Laid-Open No. 4-272637. In the figure, 1 is a circular waveguide, 2 is a ceramic disk, 4 is a flange, and 5 is a rectangular waveguide. The ceramic disc 2 is hermetically brazed in the middle of the circular waveguide 1. Generally, in such an output window a circular waveguide 1 and a ceramic disc 2
Is used because the cross-sectional area of the waveguide is large, the electric field strength is relaxed, and the allowable microwave power becomes large.

[0003]

However, when a high-power microwave is passed through the conventional output window as described above, the ceramic disk 2 is broken and the airtightness becomes insufficient. there were. Such destruction is caused by the material itself of the ceramic disc 2 that is destroyed by internal discharge due to lack of dielectric strength or heat generation due to dielectric loss, and local destruction of the ceramic disc 2 due to multipactor discharge or the like. There are some caused by the characteristics of the surface of the ceramic disk 2, such as cracks generated by various temperature rises and pin holes caused by melting. Among them, the destruction due to the material itself of the ceramic disc 2 can be improved by using aluminum ceramic having a high dielectric strength.

On the other hand, the destruction due to the characteristics of the surface of the ceramic disk 2 is about 1 to 2 nm, which is a thin film of titanium nitride, titanium oxide, chromium oxide or the like having a low secondary electron emission coefficient on the surface of the ceramic disk 2. It can be considerably improved by forming a coating film. What is multipactor discharge?
This phenomenon occurs when electrons are incident on a dielectric material with a high secondary electron emission coefficient, and the generated secondary electrons are again incident on the dielectric material under the high electric field of microwaves and are amplified like an avalanche. Is. Secondary electrons are likely to be generated in the output window in the central portion of the ceramic disc 2 having a high electric field and the outer peripheral portion of the ceramic disc 2 which is hermetically sealed. Especially the outer periphery,
As shown in FIG. 10, a ceramic disc 2 and a circular waveguide 1
And a brazing filler metal 6 and is called a triple junction 7. In order to suppress the multipactor discharge and the like, it is desirable that the coating film be sufficiently thick, but if the coating film is too thick, microwaves are reflected and the characteristics as an output window deteriorate.

The coating film is formed by a DC sputtering device, an RF sputtering device, or the like. In these devices, the central portion of the ceramic disk 2 usually tends to be thicker than the outer peripheral portion. However, it was difficult to form a uniform thickness. The electric field of microwaves passing through the output window is larger in the central portion, and the conventional coating film having a thick central portion is inconvenient. That is, when the coating film having an appropriate thickness is formed in the central portion, the thickness of the coating film is insufficient in the outer peripheral portion, and secondary electrons are easily generated. On the other hand, if a coating film having an appropriate thickness is formed on the outer peripheral portion, the thickness of the coating film at the central portion becomes too thick, so that there is a problem that microwaves are reflected.

The present invention has been made in order to solve the above problems, has a small influence on the reflection of microwaves, and sufficiently suppresses secondary electron emission from the surface of a ceramic disk and MacTipactor discharge. It is an object of the present invention to provide a highly reliable and high performance output window and a method for manufacturing the same.

[0007]

In an output window according to the present invention, a ceramic disc is arranged in the middle of a circular waveguide, and the outer peripheral portion of the ceramic disc and the inner wall surface of the circular waveguide are made of brazing material. In the output window hermetically sealed via the film, the film thickness of the central part is the film thickness of the joining part between the outer peripheral part of the ceramic disk and the inner wall surface of the circular waveguide via the brazing material on the surface of the ceramic disk. The coating film is formed to be thicker than the thickness. The coating film is made of titanium nitride, titanium oxide, or chromium oxide.

Further, in the method for manufacturing an output window according to the present invention, a ceramic disc is arranged in the middle of the circular waveguide, and the outer peripheral portion of the ceramic disc and the inner wall surface of the circular waveguide are brazing material. In the manufacturing process of the output window hermetically sealed via the center of the film thickness of the joint between the outer peripheral part of the ceramic disk and the inner wall surface of the circular waveguide on the surface of the ceramic disk via the brazing material. It is a method of forming a coating film so that it is thicker than the film thickness of the part, the process of forming the coating film on the entire surface of the ceramic disc, and covering the central part of the ceramic disc with a mask, and only the outer peripheral part. It is manufactured so as to include a step of forming a coating film. Also, the step of installing a desired target in the sputtering device, the step of installing the ceramic disk in the sputtering device by shifting the central axis of the ceramic disk by an arbitrary distance from the central axis of the target, and placing the ceramic disk in the center It is manufactured so as to include a step of forming a coating film on the surface of the ceramic disk while rotating around the axis. Further, the manufacturing is performed by including a step of installing a desired target having a hole in the center of the sputtering apparatus and a step of forming a coating film on the surface of the ceramic disk.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an output window according to the first embodiment of the present invention. In the figure, 10 is an output window in the present embodiment,
Reference numeral 1 is a circular waveguide, 2 is a ceramic disk arranged in the middle of the circular waveguide 1, and 3 is a thin film of titanium nitride, titanium oxide, chromium oxide or the like uniformly coated on the surface of the ceramic disk 2. Coating films 5 indicate rectangular waveguides provided on both sides of the circular waveguide 2, respectively. In the present embodiment, the ceramic disc 2 is arranged in the middle of the circular waveguide 1, and in the output window hermetically sealed by the circumferential portion of the ceramic disc 2 and the inner wall surface of the circular waveguide 1, the ceramic disc 2 A thin film of titanium nitride, titanium oxide, chromium oxide or the like is uniformly coated on the surface of the disc 2, and a coating film 3 having a uniform thickness is formed on the entire surface of the ceramic disc 2. The thickness of the coating film 3 is set to about 1 to 2 nm, which can sufficiently reduce the secondary electron emission coefficient and does not cause microwave reflection.

A method of manufacturing an output window according to the present embodiment,
That is, a method for uniformly forming the coating film 3 of titanium nitride, titanium oxide, chromium oxide or the like on the surface of the ceramic disk 2 with a sputtering device or the like will be described in Embodiments 3 to 5 below, and here, Will be omitted. According to the present embodiment, since the coating film 3 on the surface of the ceramic disc 2 has a uniform thickness over the entire surface, the secondary electron emission coefficient at the central portion and the outer peripheral portion of the ceramic disc 2, especially at the triple junction, is reduced, It is possible to suppress multipactor discharge. Further, since the coating film 3 has an appropriate film thickness on the entire surface of the ceramic disk 2, reflection of microwave does not occur, and a highly reliable and high performance output window can be obtained.

Embodiment 2. FIG. 2 is a sectional view showing an output window according to the second embodiment of the present invention. In the figure,
Reference numeral 10a denotes an output window in the present embodiment, 3a denotes a coating film made of a thin film of titanium nitride, titanium oxide, chromium oxide or the like coated on the surface of the ceramic disk 2. It is formed to be thicker than the central portion. In the drawings, the same or corresponding parts are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 3, the coating film 3a on the surface of the ceramic disk 2 in the present embodiment is formed such that the film thickness of the outer peripheral portion of the ceramic disk 2 is thicker than the film thickness of the central portion thereof. Thereby, the secondary electron emission coefficient at the outer peripheral portion of the ceramic disk 2 can be further reduced. Further, since the electric field at the outer peripheral portion of the ceramic disk 2 is significantly smaller than that at the central portion, the reflection of microwaves caused by the thick film of the coating film 3a is negligible. In addition, the manufacturing method of the output window in the present embodiment,
This will be described in Embodiments 3 to 5 below, and will be omitted here.

FIG. 4 is a diagram comparing the amounts of heat generated when microwaves pass through the output window according to the present embodiment and the conventional output window. In the figure, A indicates the heat generation amount of the output window according to the present embodiment, and B indicates the heat generation amount of the conventional output window. The output window in the present embodiment has a smaller heat generation amount than the conventional product,
The effect of this embodiment can be confirmed. According to the present embodiment, the coating film 3a on the surface of the ceramic disk 2 is formed so that the film thickness at the outer peripheral portion is larger than the film thickness at the central portion. It is possible to reduce the secondary electron emission coefficient at the triple junction and suppress the multipactor discharge, and it is possible to obtain a highly reliable and high-performance output window.

The present embodiment and the above-mentioned first embodiment
In the output window in, the secondary electron emission coefficient in the triple junction is obtained by using the circular waveguide 1 which is mirror-finished by electropolishing or the like, or which has no C chamfer normally provided on the outer peripheral portion of the ceramic disk 2. Can be further lowered. Further, in the present embodiment and the above-described first embodiment, the case of microwaves has been described as an example, but similar effects can be obtained for millimeter waves and high frequencies, and the present invention is effective.

FIG. 5 shows an example in which the output window in this embodiment and the first embodiment is applied to a device using microwaves.
Shown in. In the figure, 20 is an electron tube, 30 is a device that uses microwaves, and the output window 10a (or 10) is attached to the device 30. Output window 10a (or 1
0) transmits the microwave from the electron tube 20 to the device 30, and also serves to divide the electron tube 20 and the device 30. As described above, the output window 10a (or 10) in the present embodiment and the first embodiment is not only the electron tube that generates microwaves, but also a heating device, an accelerator, or a processing device that uses microwave or millimeter-wave power. Widely used for etc.

Embodiment 3. FIG. 6 is a diagram showing a method for manufacturing an output window according to the third embodiment of the present invention, showing the inside of a sputtering apparatus when a thin film of titanium nitride, titanium oxide, chromium oxide or the like is coated on the surface of a ceramic disc. ing. In the figure, 2 is a ceramic disc, 8
Is a target for forming a desired thin film, and 9 is a mask. In the present embodiment, in the manufacturing process of the output window in which the ceramic disc 2 is arranged in the middle of the circular waveguide, a thin film of titanium nitride, titanium oxide, chromium oxide or the like is formed on the surface of the ceramic disc 2 by a sputtering device. The coating method includes a step A of forming a thin film on the entire surface of the ceramic disk 2 and a step B of covering the central part of the ceramic disk 2 with a mask 9 and forming a thin film only on the outer peripheral part. Is. In the sputtering apparatus, generally, in the case of the step A of forming a thin film on the entire surface of the ceramic disc 2, the central portion of the ceramic disc 2 tends to have a larger film thickness than the outer peripheral portion. According to the manufacturing method of the embodiment, since the thin film is formed only in the outer peripheral portion in the step B, the uniform coating film 3 (FIG. 1) shown in the first embodiment or the outer periphery shown in the second embodiment. It is possible to form the coating film 3a (FIG. 2) in which the film thickness of the part is thicker than the film thickness of the central part.
The lift-off method may be performed by changing the order of step A and step B. First, the central portion of the ceramic disk 2 is covered with the mask 9 to form a thin film only on the outer peripheral portion, and then the mask 9 is formed.
Even if the film is removed and a thin film is formed on the entire surface of the ceramic disk 2, the same coating film 3 (or 3a) can be formed.

Fourth Embodiment FIG. 7 is a diagram showing a method of manufacturing an output window according to the fourth embodiment of the present invention, showing the inside of a sputtering apparatus when coating the surface of a ceramic disk with a thin film of titanium nitride, titanium oxide, chromium oxide or the like. ing. In the figure, 2 is a ceramic disk, 2
Reference symbol a denotes a central axis of the ceramic disk 2, 8 denotes a target for forming a desired thin film, and 8a denotes a central axis of the target 8. In the present embodiment, in the manufacturing process of the output window in which the ceramic disc 2 is arranged in the middle of the circular waveguide, a thin film of titanium nitride, titanium oxide, chromium oxide or the like is formed on the surface of the ceramic disc 2 by a sputtering device. As a coating method, a step of installing a desired target 8 in a sputtering apparatus and a method of installing the ceramic disk 2 in the sputtering apparatus by displacing the central axis 2a of the ceramic disk 2 from the central axis 8a of the target 8 by an arbitrary distance r And the step of forming a thin film on the surface of the ceramic disk 2 while rotating the ceramic disk 2 about its center as an axis. In the sputtering apparatus, generally, when the ceramic disk 2 and the target 8 are coaxially installed, the central part of the ceramic disk 2 tends to have a larger film thickness than the outer peripheral part. However, in the present embodiment, According to the manufacturing method, the ceramic disc 2
By disposing the center axis 2a of the target 8 and the center axis 8a of the target 8 so as to be displaced from each other, the coating film 3 (FIG. 1) having the entire surface uniform shown in FIG. It is possible to form the coating film 3a (FIG. 2) whose thickness is thicker than that of the central portion.

Embodiment 5. FIG. 8 is a diagram showing a method of manufacturing an output window according to a fifth embodiment of the present invention, showing the inside of a sputtering apparatus when coating a thin film of titanium nitride, titanium oxide, chromium oxide or the like on the surface of a ceramic disk. ing. In the figure, 2 is a ceramic disc, 8
Reference numeral 8 indicates a target, and reference numeral 88a indicates a hole provided in the center of the target 88. In the present embodiment, in the manufacturing process of the output window in which the ceramic disc 2 is arranged in the middle of the circular waveguide, a thin film of titanium nitride, titanium oxide, chromium oxide or the like is formed on the surface of the ceramic disc 2 by a sputtering device. The coating method includes a step of installing a desired target 88 having a hole 88a in the center of the sputtering apparatus, and a step of forming a thin film on the surface of the ceramic disk 2. In the sputtering apparatus, when the ceramic disk 2 and a normal target are coaxially installed, the central part of the ceramic disk 2 tends to have a larger film thickness than the outer peripheral part. According to the method, there is a hole 88a in the center.
By using the open target 88, the amount of thin film material reaching the outer peripheral portion of the ceramic disk 2 increases, so that the coating film 3 having the entire surface uniform shown in the first embodiment is formed.
(FIG. 1) or the coating film 3a shown in the second embodiment in which the film thickness of the outer peripheral portion is thicker than the film thickness of the central portion (FIG. 2).
Can be formed.

[0018]

As is evident from the foregoing description, according to the present invention, the ceramic disc is positioned in the middle of the circular waveguide, hermetically sealed with the inner wall surface of the outer peripheral portion and the circular waveguide of the ceramic disc in the output window has, on the surface of the ceramic disc, co as the thickness of the outer peripheral portion of the ceramic disc is thicker than the thickness of the central portion
By forming the computing film, ceramic disc entirely, particularly the secondary electron emission and Makuchipakuta over <br/> from the outer peripheral portion can be sufficiently suppressed, high performance output window reliability obtained .

Further, according to the manufacturing method of the output window in the present invention, the surface of the ceramic disc, quotes as the thickness of the outer peripheral portion of the ceramic disc is thicker than the thickness of the central portion
Since the wing film can be formed , it is possible to manufacture an inexpensive, reliable and high-performance output window.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an output window according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing an output window according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a film thickness distribution of a coating film of an output window according to the second embodiment of the present invention.

FIG. 4 is a diagram comparing the heat generation amounts of the output window in the second embodiment of the present invention and the conventional output window.

FIG. 5 is a diagram showing an application example of an output window in the first and second embodiments of the present invention.

FIG. 6 is a cross-sectional view showing the method of manufacturing the output window according to the third embodiment of the present invention.

FIG. 7 is a cross-sectional view showing the method of manufacturing the output window in the fourth embodiment of the present invention.

FIG. 8 is a cross-sectional view showing the method of manufacturing the output window in the fifth embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a conventional output window.

FIG. 10 is a partially enlarged sectional view showing a triple junction of an output window.

[Explanation of symbols]

1 circular waveguide, 2 ceramic disc, 2a ceramic disc central axis, 3a coating film, 4 flange, 5 rectangular waveguide, 6 brazing material, 7 triple junction, 8 target, 8a target central axis,
9 masks, 10 and 10a output window, 20 electron tubes, 3
0 instrument, 88 target, 88a hole.

Claims (5)

(57) [Claims] 1. An output window in which a ceramic disk is arranged in the middle of a circular waveguide, and an outer peripheral portion of the ceramic disk and an inner wall surface of the circular waveguide are hermetically sealed by a brazing material , On the surface of the ceramic disc, the brazing material between the outer peripheral portion of the ceramic disc and the inner wall surface of the circular waveguide is interposed.
An output window, wherein the coating film is formed so that the thickness of the bonded portion is larger than the thickness of the central portion. 2. The output window according to claim 1, wherein the coating film is made of titanium nitride, titanium oxide, or chromium oxide. 3. A ceramic disc is arranged in the middle of the circular waveguide, and the outer periphery of the ceramic disc and the circular waveguide.
In the manufacturing process of the output window whose inner wall surface is hermetically sealed by a brazing material, the outer peripheral portion of the ceramic disk and the inner wall surface of the circular waveguide are formed on the surface of the ceramic disk.
A method of forming a coating film so that the thickness of a joint portion via a corrugated material is thicker than the thickness of a central portion, the method comprising forming the coating film on the entire surface of the ceramic disc, A method of manufacturing an output window, comprising a step of covering a central portion of a ceramic disk with a mask and forming the coating film only on an outer peripheral portion. 4. A manufacturing process of an output window in which a ceramic disc is arranged in the middle of a circular waveguide, wherein the film thickness of the outer peripheral portion of the ceramic disc is controlled by a sputtering device on the surface of the ceramic disc. A method of forming a coating film to be thicker than the film thickness, the step of installing a desired target in the sputtering device, and the center axis of the ceramic disk in the sputtering device is arbitrary from the center axis of the target. And the step of forming the coating film on the surface of the ceramic disc while rotating the ceramic disc around its center as an axis. Window manufacturing method. 5. A manufacturing method of an output window in which a ceramic disc is arranged in the middle of a circular waveguide, wherein the film thickness of the outer peripheral portion of the ceramic disc is centered by a sputtering device on the surface of the ceramic disc. A method of forming a coating film so as to be thicker than the film thickness of, the step of setting a desired target having a hole in the center of the sputtering device, and the coating film on the surface of the ceramic disk. A method of manufacturing an output window, comprising the step of forming an output window.