Klystron

Abstract

To provide stable klystron.SOLUTION: A klystron includes a plurality of cavity resonators arranged side by side on a coaxial line, and the cavity resonator includes a cylinder, one drift tube and the other drift tube respectively provided on both end sides of the cylinder, one and the other support respectively supporting the drift tubes at the respective ends of the cylinder, and gap adjustment means that adjusts the spacing between the one and the other drift tubes, the cylinder has a projection protruding from one end face in parallel with the axis, one of the supports is provided in contact with the projection, and the gap adjustment means presses one of the supports toward the projection to plastically deform the projection to adjust the gap between the one drift tube and the other drift tube.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present invention relates to a klystron. [Background technology]

[0002] The klystron has multiple cavity resonators arranged on a coaxial line, and by passing the electron beam extracted from the electron gun through these cavity resonators, DC power is converted into high-frequency power through the interaction between the electron beam and the cavity resonators, and stable microwave amplification is achieved. The cavity resonators are adjusted to a resonant frequency suitable for interacting with the electron beam. On the other hand, some cavity resonators are composed of a cylinder, drift tubes provided on both ends of the cylinder, and disks (supports) that support the drift tubes at each end of the cylinder. In such a cavity resonator, the opposing drift tubes are held at a specified distance from each other, but in order to adjust the distance between the drift tubes, a thin-walled portion is provided on the disk (support) so as to surround the drift tube, and the position of the drift tube can be adjusted by plastically deforming the thin-walled portion surrounding the drift tube. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-113498 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the cavity resonator, the passing electron beam is subjected to velocity modulation and density modulation by the cavity, so that when the electron beam with density variations passes through the drift tube, a current is induced on the inner wall of the drift tube. Thus, when the klystron is operated, the inner wall of the drift tube generates losses due to the induced current, which are converted into heat and diffused to the surroundings. However, when the support has a thin wall, the thin wall can impede thermal diffusion from the inner wall of the drift tube, preventing sufficient thermal conduction in the circumferential direction of the disk, which can cause the drift tube to become very hot. If the temperature of the drift tube changes significantly, the dimensions change due to thermal expansion, which in turn changes the resonant frequency. As a result, the interaction between the cavity resonator and the electron beam is affected, causing the klystron to become unstable.

[0005] The present embodiment aims to provide a klystron that can operate stably. [Means for solving the problem]

[0006] One embodiment is a klystron comprising a plurality of cavity resonators arranged side by side on a coaxial line, the cavity resonators comprising a cylindrical body, one and another drift tubes provided on both ends of the cylindrical body, one and another supports supporting the drift tubes at each end of the cylindrical body, respectively, and a gap adjustment means for adjusting the gap between the one and another drift tubes, the cylindrical body having a protrusion protruding parallel to the axis from one end face, the one support being provided in contact with the protrusion, and the gap adjustment means adjusting the gap between the one and another drift tubes by pressing the one support toward the protrusion, thereby plastically deforming the protrusion. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic structure of a klystron according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view, partly cut away, showing a cavity resonator used in the klystron according to the embodiment. [Diagram 3] FIG. 3 is a perspective view showing a portion of the protrusion shown in FIG. 2 in a cutaway view. [Figure 4] 4(a) and (b) are cross-sectional views showing modified examples of the protrusions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment will be described in detail below with reference to the drawings. In addition, in order to clarify the description, the width, thickness, shape, etc. of each part may be shown in a schematic manner compared to the actual embodiment, but this is merely an example and does not limit the interpretation of the present invention. In this specification and each drawing, components that perform the same or similar functions as those described above with respect to the previous drawings are given the same reference numerals, and duplicate detailed descriptions may be omitted as appropriate.

[0009] First, an embodiment will be described with reference to FIGS. 1 to 3. FIG. As shown in FIG. 1, the klystron 1 according to the embodiment includes an electron gun 3, an input cavity 5, an output cavity 7, and a collector 9, which are arranged coaxially with respect to an axis K. Between the input cavity 5 and the output cavity 7, a plurality of cavity resonators 11 according to the embodiment (see FIG. 2) are provided adjacent to each other on the axis K. The electron gun 3 is provided with a cathode 3a. The input cavity 5 is provided with an input window 5a for radio frequency power (RF), and the output cavity 7 is provided with an output window 7a for radio frequency power (RF). In each of the cavities 5, 7, 11, a drift tube 13 is disposed so as to coincide with an axis K thereof. Then, the electron beam extracted from the electron gun 3 is passed through the input cavity 5 and a plurality of cavity resonators 11 (described later), whereby DC power is converted into radio frequency power due to the interaction between the electron beam and the cavity resonators 11, and the amplified radio frequency power (RF) is extracted from the output window 7a of the output cavity 7.

[0010] As shown in FIG. 2, the cavity resonator 11 comprises a cylinder 15, one drift tube 13a provided at one end of the cylinder 15, the other drift tube 13b provided at the other end of the cylinder 15, one support 17a supporting the one drift tube 13a, the other support 17b supporting the other drift tube 13b, and a gap adjustment means 19.

[0011] The cylindrical body 15 has a protrusion 21 that protrudes outward from one end face 15a in a direction parallel to the axis K. The protrusion 21 protrudes continuously from an inner peripheral surface 15c of the cylindrical body 15 and is continuous over the entire circumferential direction of the cylindrical body 15. As shown in FIG. 3, the vertical cross section of the projection 21 is substantially rectangular. As shown in FIG. 2, the cylindrical body 15 is provided with a flange 23 on the outer periphery on the side of one end face 15a, over the circumferential direction.

[0012] One drift tube 13a and the other drift tube 13b each have a cylindrical shape, with their ends facing each other and disposed at an interval of a drift tube gap d. The resonant frequency is adjusted by adjusting this drift tube gap d. One support 17a supporting one drift tube 13a and the other support 17b supporting the other drift tube 13b are each in the form of a disk with a hole formed in the center, and the disks are formed to a uniform thickness. The drift tube 13a and the drift tube 13b are inserted and fixed in the central holes of the support 17a and the support 17b, respectively. One of the supports 17 a is provided on one end surface 15 a side of the cylindrical body 15 , and is disposed so that its outer periphery abuts against the projection 21 . The other support 17b is provided on the other end face 15b side of the cylindrical body 15, and its outer periphery is closely attached to the other end face 15b and fixed thereto by brazing or the like.

[0013] Here, one end surface 15a of the cylindrical body 15 and the outer periphery of one support 17a will be described in more detail. One end surface 15a of the cylindrical body 15 is formed with a step portion 25 which rises continuously from the outer circumferential surface and forms a step with respect to the one end surface 15a. An abutment piece 29 is provided on the outer periphery of one support 17a, which is continuous with an abutment surface 27a with the projection 21 and projects in the outer periphery direction from an opposite surface 27b, and abuts against the step portion 25. The abutment piece 29 is formed over the entire circumferential direction of one support 17a. An outer peripheral end 29a of the abutment piece 29 is engaged with the inner peripheral surface of the step portion 25 and is fixed thereto by brazing or the like. An airtight space S1 surrounded by the projection 21, the step portion 25 and the abutment piece 29 is formed between the outer peripheral surface 31 of one support member 17a and one end surface 15a of the cylindrical body 15. As shown in FIG. 3, the projection 21 has communication holes 33 that communicate with the airtight space S1 and the inner space S0 of the cylindrical body 15 formed at predetermined intervals in the circumferential direction.

[0014] The gap adjusting means 19 presses one of the supports 17a towards the projection 21 to plastically deform the projection 21, thereby adjusting the drift tube gap d. The gap adjustment means 19 includes a support abutment member 35 that abuts against a surface 27b of one support 17a opposite to the projection 21, and a screw member 37 that screws into the support abutment member 35. The support abutment member 35 is formed with a pressing portion 35a that presses one of the supports 17a and a screwed portion 35b into which the screw member 37 is screwed, and the pressing portion 35a and the screwed portion 35b form a generally L-shaped cross section. The pressing portion 35a is provided at a position corresponding to the protrusion 21, and presses only the outer periphery of the one of the supports 17a. The screw member 37 is a bolt, and has a head 37 a engaged with the flange 23 and a shaft 37 b inserted through the flange 23 and screwed into the support member abutment member 35 . By screwing the screw member 37, the pressing portion 35a of the support abutment member 35 presses one of the supports 17a toward the protrusion 21, and the protrusion 21 undergoes plastic deformation, moving the one of the supports 17a toward the other support 17b, narrowing the drift tube gap d.

[0015] Next, the effects of the klystron 1 according to this embodiment will be described. In the cavity resonator 11, when the drift tube gap d is to be reduced, the screw member 37 is tightened so that one support 17a is pressed by the pressing portion 35a of the support abutment member 35, and the protrusion 21 of the cylinder 15 is plastically deformed and crushed. As a result, one drift tube 13a fixed to one support 17a approaches the other drift tube 13b, thereby reducing the drift tube gap d.

[0016] When the klystron is operated, the current loss induced by the voltage change on the inner walls of the drift tubes 13a and 13b is converted into heat and diffused to the surroundings. The one and other supports 17a, 17b have a uniform thickness and do not have thin-walled portions as in the prior art, so that the thermal diffusion of the one and other drift tubes 13a, 13b is not impeded and the heat is conducted uniformly in the circumferential direction, and is diffused throughout the one and other supports 17a, 17b and the cylinder 15. This prevents the drift tubes 13a, 13b from becoming too hot, reduces dimensional changes due to thermal expansion, and prevents changes in the resonant frequency, thereby stabilizing the operation of the klystron.

[0017] The gap adjustment means 19 has a simple structure because it is made up of the support abutment member 35 and the screw member 37 that screws into the support abutment member 35. In addition, the drift tube gap can be easily adjusted by screwing the screw member 37. The support abutment member 35 has a generally L-shaped cross section formed by the pressing portion 35a and the screwed portion 35b, and thus has a small and compact shape. Since the pressing portion 35a is located in a position corresponding to the protrusion 21, the force that crushes the protrusion 21 (the force that plastically deforms the protrusion 21) is easily transmitted.

[0018] An airtight space S1 surrounded by the protrusion 21, step 25, and abutment piece 29 is formed between the outer peripheral surface 31 of one support 17a and one end face 15a of the cylindrical body 15, and is connected to the inner space S0 within the cylindrical body 15. Therefore, even if one support 17a is displaced, the abutment piece 29 can plastically deform to follow, thereby maintaining the vacuum in the airtight space S1. The airtight space S1 and the inner space S0 can be easily communicated with each other through the communication hole 33 formed in the projection 21.

[0019] The above-described embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims.

[0020] For example, the shape of the protrusion 21 is not limited to a rectangular cross section, but may be a wedge cross section as shown in FIG. 4(a) or a semicircular cross section as shown in FIG. 4(b). Furthermore, the pressing portions 35a provided on the support-body contact member 35 do not necessarily have to be continuous in the circumferential direction, and may be provided at intervals. [Explanation of symbols]

[0021] 1...klystron, 11...cavity resonator, 13a...one drift tube, 13b...other drift tube, 17a...one support, 17b...other support, 19...gap adjustment means, 21...projection, 25...step portion, 29...abutment piece, 33...communicating hole, 35...support abutment member, 35a...pressure portion, 37...screw member, d...distance between drift tubes (drift tube gap), K...axis.

Claims

1. A plurality of cavity resonators are arranged side by side on a coaxial line, the cavity resonator comprises a cylinder, one and the other drift tubes provided on both ends of the cylinder, one and the other supports supporting the drift tubes at each end of the cylinder, and a gap adjusting means for adjusting the gap between the one and the other drift tubes, the cylindrical body has a protrusion protruding from one end surface in parallel with the axis, and the one support body is provided in contact with the protrusion, the gap adjusting means adjusts the gap between the one and the other drift tubes by pressing the one support member against the protrusion to plastically deform the protrusion.

2. 2. The klystron according to claim 1, wherein the gap adjustment means comprises a support abutment member that abuts against the one of the supports, and a screw member that screws into the support abutment member, and the support abutment member presses the one of the supports toward the protrusion by screwing the screw member.

3. 3. The klystron according to claim 2, wherein the support abutment member has a pressing portion protruding toward the one support at a position corresponding to the protrusion.

4. 2. The klystron according to claim 1, wherein the one end face of the cylindrical body has a step portion facing an outer peripheral surface of the one support on the outer peripheral side of the protrusion, the outer peripheral surface of the one support has an abutment piece abutting the step portion, and an airtight space surrounded by the protrusion, the step portion, and the abutment piece is formed between the outer peripheral surface of the one support and the one end face of the cylindrical body.

5. 5. The klystron according to claim 4, wherein the projection is formed with a communication hole communicating with an inner space of the cylindrical body.

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