JP2016081648A - High frequency transmission window structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency transmission window structure which hardly generates clacks in the vicinity of a joint area of the high frequency transmission window.SOLUTION: The high frequency transmission window structure 20 includes a high frequency transmission window 30 and a sleeve 31. The high frequency transmission window 30 is formed of a ceramic and has a joint area 34 on an outer periphery. The sleeve 31 constitutes a high frequency transmission path and has a joint area 37 with a joint area 34 of the high frequency transmission window 30 which is joined to the inner peripheral surface by soldering, and a groove 38 which is formed along the side of the part 37 and a part of the joint area 34 is opposed thereto.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a high-frequency transmission window structure used for high-frequency output.

  Conventionally, a microwave electron tube such as a klystron that amplifies a high frequency (microwave) is provided with a high frequency transmission window structure in an output waveguide in order to output a high frequency to the outside while keeping the inside vacuum.

  The high-frequency transmission window structure includes a high-frequency transmission window that is air-tight and transmits high-frequency waves, and a metal sleeve such as copper that forms a transmission path for a high-frequency signal by joining the outer periphery of the high-frequency transmission window by brazing. For example, ceramic such as alumina is used as the material of the high-frequency transmission window. The high-frequency transmission window has a metallized layer which is a thin metal layer on the joint surface with the sleeve, and is joined to the sleeve by brazing via the metallized layer.

  The high-frequency transmission window structure is exposed to a high temperature of, for example, 1000 degrees or more when assembled by brazing. In addition, the high-frequency transmission window structure is also exposed to a high temperature of, for example, 400 ° C. or higher for heating even during exhaust for vacuuming the inside after assembling the tube of the microwave electron tube.

  The thermal expansion coefficient of the material differs between the ceramic high-frequency transmission window and the metal sleeve. Therefore, a tensile stress is generated in the high-frequency transmission window at the joint between the high-frequency transmission window and the sleeve due to a temperature change when the temperature increases from room temperature to a high temperature state or when the temperature decreases from the high temperature state to room temperature. In particular, stress concentration tends to occur in the high-frequency transmission window at the end in the width direction of the joint surface of the high-frequency transmission window. As a result, cracks may occur toward the inside of the high frequency transmission window starting from the end of the joint surface of the high frequency transmission window. When this crack penetrates the high-frequency transmission window, there is a problem that the airtightness of the microwave electron tube cannot be maintained.

JP-A-9-63490

  The problem to be solved by the present invention is to provide a high-frequency transmission window structure in which cracks are unlikely to occur in the vicinity of the joint surface of the high-frequency transmission window.

  The high-frequency transmission window structure of the present embodiment includes a high-frequency transmission window and a sleeve. The high-frequency transmission window is made of ceramic and has a joint surface on the outer periphery. The sleeve constitutes a high-frequency transmission line, and has a joint portion on the inner peripheral surface where the joint surface of the high-frequency transmission window is joined by brazing, and is provided along a side portion of the joint portion. Have opposite groove portions.

It is a sectional view of a part of the high frequency transmission window structure showing the first embodiment. It is sectional drawing which shows schematic structure of a high frequency transmission window structure same as the above. It is sectional drawing of the microwave electron tube using a high frequency transmission window structure same as the above. It is sectional drawing of a part of high frequency transmission window structure which shows 2nd Embodiment.

  Hereinafter, a first embodiment will be described with reference to FIGS. 1 to 3.

  FIG. 3 is a cross-sectional view of a microwave electron tube using a high-frequency transmission window structure. 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 13 a that generates an electron beam 12 and an anode 13 b that accelerates the electron beam 12.

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

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

  Among the plurality of resonance cavities 15a to 15e constituting the high frequency interaction unit 14, a high frequency signal input unit 17, for example, a coaxial line, is connected to the resonance cavity 15a located on the electron gun unit 11 side. 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 high-frequency transmission window structure 20 for outputting a high frequency to the outside while keeping the inside of the microwave electron tube 10 in a vacuum.

  A drift tube 21 having the same diameter is connected 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 partial cross-sectional view of the high-frequency transmission window assembly 20, and FIG. 2 is a cross-sectional view showing a schematic structure of the high-frequency transmission window assembly 20. The high-frequency transmission window structure 20 includes a high-frequency transmission window 30 that is airtight and transmits high frequencies, a sleeve 31 that constitutes a high-frequency transmission path, and a wire 32 that is wound around the sleeve 31 where the high-frequency transmission window 30 is brazed. It has.

  As a material of the high-frequency transmission window 30, for example, ceramic such as alumina is used. The high frequency transmission window 30 is formed in a disc shape. A joint surface 34 to be joined to the sleeve 31 is formed on the outer peripheral surface of the high-frequency transmission window 30. The high-frequency transmission window 30 has a metallized layer, which is a thin metal layer, on the joining surface 34, and melts a plate-like brazing material inserted between the high-frequency transmission window 30 and the sleeve 31 at a high temperature, thereby allowing the sleeve 31 to Joined with. At both ends of the joint surface 34 of the high-frequency transmission window 30, that is, the corners on both sides in the width direction of the high-frequency transmission window 30, inclined surfaces (chamfered portions) 35 that are obliquely cut are formed. The width W of the bonding surface 34 is smaller than the thickness dimension of the high-frequency transmission window 30 in the width direction.

  As the material of the sleeve 31, for example, a metal such as copper is used. The sleeve 31 is formed in a cylindrical shape. A joint portion 37 that joins the joint surface 34 of the high-frequency transmission window 30 is formed on the inner peripheral surface of the sleeve 31, and two groove portions 38 are formed along both side portions of the joint portion 37. The joint portion 37 and the two groove portions 38 are formed over the entire circumference of the inner peripheral surface of the sleeve 31. The groove portion 38 has inner side surfaces 39 on both sides and a groove bottom surface 40 on the back side of the groove, and an opening portion 41 that opens to the inner peripheral surface of the sleeve 31 is formed on the groove inlet side. The cross-sectional shape of the groove portion 38 in this embodiment is formed in a rectangular shape in which the inner side surfaces 39 on both sides are orthogonal to the central axis of the sleeve 31.

  An interval X between the two groove portions 38 (width X of the joint portion 37) is smaller than the width W of the joint surface 34 of the high-frequency transmission window 30. The high frequency transmission window 30 is installed inside the sleeve 31 so that both end portions of the joint surface 34 of the high frequency transmission window 30 face the groove portions 38.

  The sleeve 31 may have only one groove portion 38. In this case, the high frequency transmission window 30 may be installed so that the joint surface 34 of the high frequency transmission window 30 faces the groove portion 38.

  At the time of brazing, the wire 32 is wound around the outside of the sleeve 31 where the high-frequency transmission window 30 is brazed, and serves to fix the position of the high-frequency transmission window 30 and the sleeve 31. The wire 32 is formed of a metal material such as molybdenum having a smaller coefficient of thermal expansion than the sleeve 31. The number of windings of the wire 32 around the sleeve 31 is arbitrary.

  The high-frequency transmission window structure 20 joins the high-frequency transmission window 30 and the sleeve 31 by brazing. At the time of brazing, the high frequency transmission window 30 and the sleeve 31 are joined by melting a plate-like brazing material inserted between the high frequency transmission window 30 and the sleeve 31 at a high temperature.

  At this time, since the sleeve 31 includes the groove portion 38, the meniscus 44 of the brazing material 43 is formed between the end portion of the joint surface 34 of the high-frequency transmission window 30 and the inner side surface 39 of the groove portion 38.

  By the way, the high-frequency transmission window structure 20 is exposed to a high temperature of, for example, 1000 degrees or more during assembly by brazing. In addition, the high-frequency transmission window assembly 20 is exposed to a high temperature of, for example, 400 ° C. or higher for heating even during exhaust for vacuuming the inside after assembling the tube of the microwave electron tube 10. The thermal expansion coefficient of the material differs between the ceramic high-frequency transmission window 30 and the copper sleeve 31, for example. Therefore, a tensile stress is generated in the high-frequency transmission window 30 at the joint portion between the high-frequency transmission window 30 and the sleeve 31 due to a temperature change from the room temperature to the high temperature state or a temperature change at the time of the temperature decrease from the high temperature state to the room temperature. Then, stress concentration tends to occur in the high frequency transmission window 30 at the end portion of the joint surface 34 of the high frequency transmission window 30. As a result, cracks may occur toward the inside of the high frequency transmission window 30 starting from the end of the joint surface 34 of the high frequency transmission window 30. If this crack penetrates the high-frequency transmission window 30, the microwave electron tube 10 cannot be kept airtight.

  According to the high frequency transmission window assembly 20 of the first embodiment, the meniscus 44 of the brazing material 43 is formed at the joint portion between the high frequency transmission window 30 and the sleeve 31, so that stress concentration that tends to occur in the high frequency transmission window 30 is increased. It is mitigated and it becomes possible to make the high frequency transmission window 30 less likely to crack.

  Further, the sleeve 31 has two groove portions 38 along both side portions of the joint portion 37, and the interval X between the two groove portions 38 is smaller than the width W of the joint surface 34 of the high-frequency transmission window 30. Both end portions of the joining surface 34 of the transmission window 30 face the groove 38, stress concentration is mitigated at both ends of the joining surface 34 of the high-frequency transmission window 30, and cracks are less likely to occur in the high-frequency transmission window 30. It becomes.

  Next, FIG. 4 shows a second embodiment. In addition, the same code | symbol is used about the same structure as 1st Embodiment, and the description about the structure and effect is abbreviate | omitted.

  The cross-sectional shape of the groove portion 38 of the sleeve 31 is formed in a trapezoidal shape. The trapezoid refers to a shape connecting the four corner points of the cross section of the groove 38. That is, the groove 38 is formed in a trapezoidal shape so that the width of the opening 41 is wider than the width of the groove bottom 40 and the inner side surfaces 39 on both sides expand from the groove bottom 40 toward the opening 41. The angle θ formed by the joint surface 34 of the high-frequency transmission window 30 and the inner side surface 39 of the groove 38 that intersects the joint surface 34 is smaller than 90 degrees.

  Since the sleeve 31 includes the groove portion 38, the meniscus 44 of the brazing material 43 is formed between the end portion of the joint surface 34 of the high-frequency transmission window 30 and the inner side surface 39 of the groove portion 38.

  According to the high-frequency transmission window assembly 20 of the second embodiment, the meniscus 44 of the brazing material 43 is formed at the joint between the high-frequency transmission window 30 and the sleeve 31, so that stress concentration that tends to occur in the high-frequency transmission window 30 is increased. It is mitigated and it becomes possible to make the high frequency transmission window 30 less likely to crack.

  In addition, since the inner side surface 39 of the groove portion 38 is inclined at an angle θ smaller than 90 degrees, the area where the brazing material 43 forming the meniscus 44 is in contact with the sleeve 31 can be easily increased, and the bonding strength can be increased. it can.

  According to the high-frequency transmission window structure 20 of at least one embodiment described above, the meniscus 44 of the brazing material 43 is formed at the joint portion between the high-frequency transmission window 30 and the sleeve 31, and thus easily occurs in the high-frequency transmission window 30. The stress concentration is relaxed, and it is possible to make it difficult for the high-frequency transmission window 30 to crack.

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

20 High-frequency transmission window structure
30 High-frequency transmission window
31 sleeve
34 Joint surface
37 joints
38 Groove

Claims (3)

A ceramic high-frequency transmission window having a joint surface on the outer periphery;
A high-frequency transmission line is configured, and an inner peripheral surface has a joint portion where the joint surface of the high-frequency transmission window is joined by brazing, and is provided along a side portion of the joint portion. A high-frequency transmission window structure, comprising: a sleeve having groove portions facing each other. 2. The high-frequency transmission window structure according to claim 1, wherein the sleeve has two groove portions along both side portions of the joint portion, and an interval between the two groove portions is smaller than a width of the joint surface. . 3. The high-frequency transmission window structure according to claim 1, wherein an angle formed between the joint surface and an inner surface of the groove portion intersecting the joint surface is smaller than 90 degrees.

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