JP6674175B2 - Airtight window structure for microwave electron tube - Google Patents

Description

  Embodiments of the present invention generally relate to a hermetic window structure for a microwave electron tube used for a microwave electron tube.

  A microwave electron tube such as a klystron for amplifying a microwave outputs a microwave to the outside while keeping the inside in a vacuum, and thus has an airtight window structure for a microwave electron tube at an output portion thereof.

  The hermetic window structure for a microwave electron tube includes a first waveguide provided with a first flange at an end, a common output transmission line together with the first waveguide, and a second flange provided at an end. A second waveguide provided, a ceramic window that airtightly partitions the inside of the third waveguide between the first flange and the second flange, and transmits microwaves, and a ceramic window for fastening the waveguides, for example. It is composed of a fastening body such as a screw. The ceramic window is, for example, alumina and is joined to the third waveguide made of a metal such as copper, for example, by brazing.

  Conventionally, the hermetic window structure for a microwave electron tube is fastened by a fastening body such as a screw penetrating both the first flange and the second flange. When such a fastening method is employed, since the entire third waveguide receives a compressive force, a force is also applied to the periphery of the ceramic window, and a stress concentration occurs at a joint between the third waveguide and the ceramic window. Easy to occur.

  Further, after assembling, the microwave electron tube is evacuated while being heated in order to evacuate the inside. At this time, the hermetic window structure for the microwave electron tube is exposed to a high temperature of, for example, 400 degrees or more. The material of the ceramic window and the third waveguide made of metal have different coefficients of thermal expansion. Therefore, further stress concentration due to thermal stress occurs at the joint between the third waveguide and the ceramic window due to the temperature change. As a result, cracks sometimes occur toward the inside of the ceramic window starting from the end of the joint surface between the third waveguide and the ceramic window. When the crack penetrates the ceramic window, there is a problem that the airtightness of the microwave electron tube cannot be maintained.

JP-A-11-186802

  The problem to be solved by the present invention is to provide a hermetic window structure for a microwave electron tube in which stress concentration does not easily occur in a ceramic window during assembly.

The hermetic window structure for a microwave electron tube of the present embodiment forms a microwave transmission path, a first waveguide having a first flange provided at an end portion, and a microwave transmission path together with the first waveguide. A second waveguide having a second flange provided at an end thereof, a first waveguide and a second waveguide having a thick wall portion having the same outer diameter as the first flange and the second flange around the second waveguide; And a third waveguide having a ceramic window through which microwaves are transmitted and airtightly separated from each other. The first waveguide has a first groove portion provided annularly on an end face of the first flange. The second waveguide has a second groove provided annularly on the end face of the second flange. The third waveguide is provided at both ends of the first flange and the second flange opposed to the end faces, and has annular projections respectively fitted into the first groove of the first flange and the second groove of the second flange. It has internal threads provided at both ends of the thick portion facing the end faces of the flange and the second flange, respectively. With the first groove of the first flange, the second groove of the second flange, and the protrusion of the third waveguide fitted respectively, the end faces of the first and second flanges and the end face of the third waveguide are Bolts each having a gap between the first and second flanges are screwed into female threads of the third waveguide, respectively. the third waveguide are separately fastened respectively.

It is sectional drawing of the airtight window structure for microwave electron tubes which shows 1st Embodiment. It is sectional drawing of the microwave electron tube using the said airtight window structure for microwave electron tubes. It is sectional drawing of the airtight window structure for microwave electron tubes which shows 2nd Embodiment.

  Hereinafter, the first embodiment will be described with reference to FIGS.

  First, FIG. 2 is a cross-sectional view of a microwave electron tube using the hermetic window structure for a microwave electron tube. The microwave electron tube 10 is, for example, a klystron. The microwave electron tube 10 includes an electron gun unit 11. The electron gun unit 11 includes a cathode 13a for generating an electron beam 12, and an anode 13b for accelerating the electron beam 12.

  A high-frequency interaction section 14 is provided in front of the electron gun section 11 with respect to the traveling direction of the electron beam 12. The high-frequency interaction unit 14 includes, for example, five resonance cavities 15a to 15e arranged in the traveling direction of the electron beam 12.

  A collector 16 for capturing the electron beam 12 is provided further in front of the high-frequency interaction unit 14.

  Of the plurality of resonance cavities 15a to 15e constituting the high-frequency interaction unit 14, the resonance cavity 15a located on the electron gun unit 11 side is connected to a high-frequency signal input unit 17, for example, a coaxial line. An amplified high-frequency output section 18, for example, a waveguide 19, is connected to the resonance cavity 15e located on the collector 16 side. The waveguide 19 is provided with a microwave electron tube hermetic window structure 20 for outputting a high frequency to the outside while keeping the inside of the microwave electron tube 10 at a vacuum.

  The drift tube 21 connects between the electron gun unit 11 and the high-frequency interaction unit 14, between the plurality of resonance cavities 15a to 15e, and between the high-frequency interaction unit 14 and the collector 16.

  FIG. 1 is a sectional view of a hermetic window structure 20 for a microwave electron tube. The hermetic window structure 20 for a microwave electron tube includes a first waveguide 31, a second waveguide 32, and a third waveguide 33. The first waveguide 31, the second waveguide 32, and the third waveguide 33 are made of a metal such as copper, for example.

  Each of the first waveguide 31 and the second waveguide 32 forms a series of microwave transmission paths 34 for transmitting microwaves, and is connected to the microwave electron tube 10. A first flange 31a and a second flange 32a are provided at ends of the first waveguide 31 and the second waveguide 32, respectively.

  The third waveguide 33 is disposed between the first waveguide 31 and the second waveguide 32. At both ends of the third waveguide 33, third flanges 33a for connecting to the first flange 31a and the second flange 32a, respectively, are provided. Note that the third flange 33a may not have the same shape at both ends as long as it is connected to the first flange 31a and the second flange 32a, respectively.

  The cross-sectional area of the third waveguide 33 is provided larger than the cross-sectional areas of the first waveguide 31 and the second waveguide 32. Inside the third waveguide 33, there is provided a ceramic window 35 that keeps airtight and transmits microwaves. For the ceramic window 35, for example, a material such as alumina is used.

  The first flange 31a and the third flange 33a, and the second flange 32a and the third flange 33a are separately fastened by fasteners 36, respectively. The fastener 36 includes, for example, a bolt 36a and a nut 36b.

  By the way, when assembling the hermetic window structure 20 for a microwave electron tube, when the third waveguide 33 is structured to be compressed from both sides, a force is also applied to the periphery of the ceramic window 35 and the third waveguide 33 is Stress concentration will occur at the joint with the ceramic window 35. After assembling, the microwave electron tube 10 is evacuated while being heated to evacuate the inside. At this time, the hermetic window structure for microwave electron tube 20 is exposed to a high temperature of, for example, 400 degrees or more. Since the coefficient of thermal expansion of the material is different between the ceramic window 35 and the third waveguide 33 made of metal, stress concentration is further caused by thermal stress at the junction between the third waveguide 33 and the ceramic window 35 due to a temperature change. . As a result, cracks may be generated from the end of the joint surface between the third waveguide 33 and the ceramic window 35 toward the inside of the ceramic window 35. When the crack penetrates through the ceramic window 35, the microwave electronic tube 10 cannot be kept airtight.

  In the hermetic window structure 20 for a microwave electron tube according to the first embodiment, the first flange 31a and the third waveguide 33 and the second flange 32a and the third waveguide 33 are separately fastened. As a result, the third waveguide 33 is not compressed as a whole, reduces stress concentration occurring at the joint between the third waveguide 33 and the ceramic window 35, and is less likely to crack in the ceramic window 35. It is possible to do.

  Further, since the third waveguide 33 is provided with the flange 33a for fastening to the first flange 31a and the second flange 32a, the first flange 31a, the flange 33a of the third waveguide 33, and the third The second flange 32a and the flange 33a of the third waveguide 33 can be individually fastened.

  Next, a hermetic window structure 20 for a microwave electron tube according to a second embodiment will be described with reference to FIG. Note that the same components as those of the first embodiment are denoted by the same reference numerals, and the description of the configurations and the functions and effects is omitted.

  FIG. 3 is a cross-sectional view of the hermetic window structure 20 for a microwave electron tube according to the second embodiment.

  The first flange 31a and the second flange 32a are formed in a circular shape, and are provided with annular first groove portions 31b and second groove portions 32b on the end surfaces, respectively.

  The third waveguide 33 is a cylindrical waveguide. The cross-sectional area of the third waveguide 33 is provided larger than the cross-sectional areas of the first waveguide 31 and the second waveguide 32. At both ends of the third waveguide 33, there are provided annular projections 33b respectively fitted into the first groove 31b of the first flange 31a and the second groove 32b of the second flange 32a.

  Around the third waveguide 33, a thick portion 33c having a thickness equal to or larger than the first flange 31a or the second flange 32a is provided. The thick portion 33c is provided with a female screw 33d to which a bolt 36a of a fastener 36 inserted through the first flange 31a and the second flange 32a is screwed.

  In the hermetic window structure 20 for a microwave electron tube according to the second embodiment, the first flange 31a and the third waveguide 33 and the second flange 32a and the third waveguide 33 are separately fastened. As a result, the third waveguide 33 is not compressed as a whole, reduces stress concentration occurring at the joint between the third waveguide 33 and the ceramic window 35, and is less likely to crack in the ceramic window 35. It is possible to do.

  In addition, in the second embodiment, the first waveguide 31 and the second waveguide 32 are directly fastened by the screws 36a screwed to the female threads 33d of the third waveguide 33, respectively. The number of components used can be reduced.

  In the second embodiment, when the thick portion 33c extends over half of the entire length of the third waveguide 33, the mechanical strength of the third waveguide 33 increases, and the deformation of the third waveguide 33 is reduced. Can be smaller.

  Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These new embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and their equivalents.

20 Airtight window structure for microwave electron tube
31 First waveguide
31a 1st flange
31b first groove
32 Second waveguide
32a Second flange
32b second groove
33 Third waveguide
33b protrusion
33c thick part
33d female screw
34 Microwave transmission line
35 ceramic windows
36a bolt

Claims (1)

A first waveguide having a microwave transmission path and a first flange provided at an end; and a first waveguide having the microwave transmission path together with the first waveguide and having a second flange provided at an end. A second waveguide, and a thick wall portion having the same outer diameter as the first flange and the second flange around the waveguide, and hermetically partitioning the first waveguide and the second waveguide therein. A third waveguide having a ceramic window that transmits microwaves, the hermetic window structure for a microwave electron tube ,
The first waveguide has a first groove portion provided annularly on an end surface of the first flange,
The second waveguide has a second groove portion provided in an annular shape on an end surface of the second flange,
The third waveguide is provided at both ends of the first and second flanges facing the end faces of the first and second flanges, and is annularly fitted into the first groove of the first flange and the second groove of the second flange, respectively. And a female screw provided at each end of the thick portion facing the end face of the first flange and the second flange,
With the first groove of the first flange and the second groove of the second flange and the protrusion of the third waveguide fitted respectively, the end faces of the first and second flanges and A gap is provided between the first waveguide and the end face of the third waveguide, and bolts that respectively penetrate the first flange and the second flange are screwed into the female threads of the third waveguide, respectively . flange and the third waveguide, and the second flange and the third microwave electron tube for airtight window assembly, wherein the waveguide is separately fastened respectively.

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