JP2018106977A - Multi-beam klystron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-beam klystron capable of making electric field intensity uniform at respective positions that respective electron beams of a nose pass.SOLUTION: A multi-beam klystron comprises a cavity 20 to which a port 39 for inputting or outputting a high frequency is connected. The cavity 20 comprises a cavity body 30, a nose 31, a plurality of beam holes 32, and a slit 33. The cavity body 30 has an outer peripheral wall 35 formed cylindrically having a center axis 12 of the cavity 20 as the center, and the port 39 is connected to the outer peripheral wall 35. The nose 31 projects from an end face side of the cavity body 30 into the cavity body 30 along on a circumference having the center axis 12 as the center. The plurality of beam holes 32 are provided for the nose 31 to be arranged respectively on the circumference having the center axis 12 as the center, and electron beams pass through them. The slit 33 is made in the nose 31.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a multi-beam klystron having a cavity.

  There are multi-beam klystrons that use multiple electron beams. This multi-beam klystron has a plurality of cavities. This cavity has an input cavity that modulates the velocity of the electrons with the input high frequency, an intermediate cavity that increases the high frequency component by bunching the electron beam with the high frequency component of the electrons given by the input cavity, and the increase There is an output cavity that converts the high-frequency component into RF and extracts the RF to the outside.

  The cavity is cylindrical, and a plurality of noses each having a beam hole project from the both end faces in the axial direction of the cavity on the circumference centering on the center axis of the cavity, and face each other. And a plurality of electron beams passing through the beam hole through gaps between the noses.

  The intermediate cavity has an axisymmetric structure around the central axis, but the input and output cavities have an axisymmetric structure around the central axis because ports for inputting and outputting high frequencies are connected. is not.

  For this reason, in the cavity to which the port is not connected, the electromagnetic field distribution is axisymmetric, and the electric field strength of each nose gap has the same value.

  On the other hand, in the cavity to which the port is connected, the electric field leaks from the port, and the electric field strength of each nose gap may vary. In a multi-beam klystron in which a plurality of nose gaps are arranged on the circumference, this tendency becomes more prominent as the gap arrangement circumference increases. If the electric field strength of each nose gap is not the same, variations in the acceleration and deceleration of electrons occur, and an efficient high-frequency amplification operation cannot be expected.

  Therefore, in the cavity to which the port is connected, the inner surface of the outer peripheral wall of the cavity is decentered from the center axis of the cavity in the direction away from the port, and the electric field strength of each nose gap is corrected and made uniform. Structure is adopted.

  However, with the structure in which the inner surface of the outer peripheral wall of the cavity is decentered from the center axis of the cavity in the direction away from the port, lathe machining with concentric cores cannot be performed when parts are processed, and the machining process becomes complicated. Cost. Therefore, it is desirable to make the electric field strength of each nose gap uniform without decentering the inner surface of the outer peripheral wall of the cavity.

JP 2008-147027 A

  The problem to be solved by the present invention is to provide a multi-beam klystron capable of equalizing the electric field intensity at each position through which each electron beam of the nose passes.

  The multi-beam klystron of this embodiment includes a cavity to which a port for inputting or outputting a high frequency is connected. The cavity includes a cavity body, a nose, a plurality of beam holes and a slit. The cavity body has an outer peripheral wall formed in a cylindrical shape centered on the central axis of the cavity, and a port is connected to the outer peripheral wall. The nose projects from the end face side of the cavity body into the cavity body along a circumference centered on the central axis. The plurality of beam holes are provided in the nose so as to be arranged on a circumference centered on the central axis, and the electron beam passes therethrough. The slit is provided in the nose.

It is sectional drawing of FIG. 2A-A view of the cavity of the multi-beam klystron which shows 1st Embodiment. It is sectional drawing of FIG. 3B-B view of a cavity same as the above. It is a top view of a cavity same as the above. It is sectional drawing of a multi-beam klystron same as the above. It is a graph which shows the relationship between the position of the nose of a cavity same as the above, and electric field strength. It is a graph which shows the relationship between the position of the independent nose of a cavity, and electric field strength in the comparative example which has a several independent nose in a cavity and does not decenter the inner surface of the outer peripheral wall of a cavity. It is a graph which shows the passage characteristic of S parameter in a comparative example with a plurality of independent noses in a cavity. It is a graph which shows the passage characteristic of S parameter in a comparative example with one nose in a cavity. It is sectional drawing of the cavity which shows 2nd Embodiment.

  Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 8.

  FIG. 4 shows a multi-beam klystron 10.

  The multi-beam klystron 10 includes a klystron body 11 and a focusing magnetic field device (not shown) that is disposed around the klystron body 11 and focuses an electron beam in the klystron body 11. In FIG. 4, reference numeral 12 denotes the central axis of the multi-beam klystron 10.

  The klystron body 11 includes an electron gun unit 14 that generates a plurality of electron beams 13 on the circumference of a predetermined radius from the central axis 12, and a high-frequency interaction that amplifies high-frequency power by the interaction between the electron beam 13 and a high-frequency electric field. Unit 15, an input unit 16 for inputting high-frequency power to the high-frequency interaction unit 15, an output unit 17 for outputting high-frequency power from the high-frequency interaction unit 15, a collector unit 18 for capturing the electron beam 13 that has passed through the high-frequency interaction unit 15 It has.

  The high-frequency interaction unit 15 is arranged on a circumference having a predetermined radius from the central axis 12, and a plurality of drift tubes 19 through which the respective electron beams 13 pass, and the drift tubes 19 extend along the traveling direction of the electron beam 13. It has a plurality of connected cavities 20. The cavity 20 includes an input cavity 21 connected to the input unit 16, a plurality of intermediate cavities 22, and an output cavity 23 connected to the output unit 17.

  Next, FIGS. 1 to 3 show the cavity 20. The cavity 20 is an output cavity 23.

  The cavity 20 is provided in a cavity body 30, a nose 31 protruding into the cavity body 30 from the end face side of the cavity body 30, a plurality of beam holes 32 provided in the nose 31, and a nose 31. Provided with slits 33 and the like.

  The cavity body 30 is made of a metal material having good conductivity, such as copper, and is formed in a cylindrical shape with the central axis 12 as the center. The cavity main body 30 has an outer peripheral wall 35, an inner peripheral wall 36, and axial end face walls 37, and a cylindrical space portion 38 forming the cavity 20 is formed inside the cavity main body 30 by these. Yes. The outer surface and inner surface of the outer peripheral wall 35 and the outer surface and inner surface of the inner peripheral wall 36 are formed concentrically around the central axis 12, and therefore the cavity 20 is a coaxial cavity. A port 39 of the output unit 17 is connected to the outer peripheral wall 35.

  The noses 31 protrude from the both end surface walls 37 of the cavity main body 30 toward the inside (space portion 38) of the cavity main body 30, respectively. These noses 31 protrude between the outer peripheral wall 35 and the inner peripheral wall 36 along a circumference with a predetermined radius centered on the central axis 12. These noses 31 are divided into two by a slit 33 and have a pair of semi-ring-shaped integrated noses 41. A gap 42 having a predetermined interval is formed between the noses 31 facing each other. A position where each beam hole 32 of the nose 31 is provided is referred to as a nose portion 43.

  Each of the plurality of beam holes 32 communicates with the drift tube 19 and the electron beam 13 passes therethrough. Each beam hole 32 is provided in the nose 31 so as to be disposed on the circumference of a predetermined radius centered on the central axis 12. The number of beam holes 32 is six, for example, arranged at equal intervals on the circumference, an intermediate portion of adjacent beam holes 32 is arranged so as to face the port 39, and opposite to the port 39 An intermediate portion of adjacent beam holes 32 is also arranged on the side.

  The slit 33 is provided at an intermediate portion of the adjacent beam hole 32 (nose portion 43) of the nose 31. The slit 33 has a first slit 45 provided on the port 39 side of the nose 31 and a second slit 46 provided on the opposite side to the port 39 side of the nose 31. The interval w1 between the first slits 45 and the interval w2 between the second slits 46 are arbitrarily set in order to make the electric field strength in the gap 42 of the nose 31 uniform. In the present embodiment, the distance w1 between the first slits 45 is wider than the distance w2 between the second slits 46. Further, the interval w1 between the first slits 45 is smaller than the opening width of the port 39. The slit 33 divides the nose 31 provided along the circumference into a pair of integrated noses 41.

  The cavity 20 is configured to be coupled to a plurality of electron beams 13 passing through a plurality of beam holes 32 through gaps 42 between nose 31 facing each other.

  FIG. 6 is a graph showing the relationship between the position of the independent nose of the cavity and the electric field strength in a comparative example in which the cavity has a plurality of independent noses and the inner surface of the outer peripheral wall of the cavity is not decentered. . The plurality of independent noses are not provided in an integrated form like the integrated nose 41, but are independent from each other. The horizontal axis of FIG. 6 represents the distance of each independent nose from the central axis of the cavity, and the vertical axis represents the electric field strength at the gap of each independent nose. In FIG. 6, C is the electric field strength at the gap of the independent nose closest to the port, D is the electric field strength at the gap of the independent nose between the position closest to the port and the far position, and E is the highest from the port. It is the electric field strength at the gap of the independent nose at a far position. As can be seen from FIG. 6, in the cavity connected to the port, when the inner surface of the outer peripheral wall of the cavity is not decentered due to the influence of the electric field leaking from the port, the electric field strength C at the gap of each independent nose, Variations occur in D and E.

  On the other hand, FIG. 5 shows a graph representing the relationship between the position of the nose 31 of the cavity 20 and the electric field strength in the present embodiment.

  A nose 31 (integrated nose 41) projects along a circumference of a predetermined radius centered on the central axis 12, and the nose 31 (integrated nose 41) is provided with a plurality of beam holes 32 and slits. Since 33 is provided, the electric field strengths C, D, and E in the gaps 42 at the positions of the respective beam holes 32 (the respective nose portions 43) of the nose 31 are made substantially uniform.

  The electric field distribution in the cavity 20 is adjusted by the slit 33 provided in the nose 31 so that the electric field strengths C, D, and E can be made substantially uniform. In addition, since the slit 33 includes the first slit 45 provided on the port 39 side of the nose 31 and the second slit 46 provided on the opposite side to the port 39 side of the nose 31, the first slit 45 is provided. By separately adjusting the interval w1 of the slits 45 and the interval w2 of the second slits 46, the electric field strengths C, D and E at the gaps 42 at the positions of the respective beam holes 32 (each nose portion 43) of the nose 31 can be obtained. It can be arbitrarily adjusted, and the electric field strengths C, D, and E can be made substantially uniform.

  Then, as a result of the adjustment test of the interval w1 between the first slits 45 and the interval w2 between the second slits 46, the electric field strength is obtained when the interval w1 between the first slits 45 is wider than the interval w2 between the second slits 46. C, D, and E were confirmed to be substantially uniform.

  FIG. 7 is a graph showing the S parameter pass characteristics in a comparative example having a plurality of independent noses in the cavity. In this case, if the interval between the plurality of independent noses on the circumference is wide, resonance points may be formed in the vicinity of the operating frequency by the number of independent noses in one cavity. On the other hand, when there is one independent nose in one cavity, as shown in FIG. 8, there is one resonance point near the operating frequency. In the state of FIG. 7, the phases other than the zero mode do not match, and the electric field intensity peak values are different even in the zero mode. As a result, the conversion efficiency to high frequency is reduced. Therefore, it is important that the electric field strengths of the gaps have the same value, and as shown in FIG. 8, it is necessary to have one resonance point near the operating frequency.

  In the present embodiment, a nose 31 (integrated nose 41) projects along a circumference of a predetermined radius centered on the central axis 12, and a plurality of beam holes 32 are provided in the nose 31 (integrated nose 41). Therefore, as shown in FIG. 8, one resonance point in the vicinity of the operating frequency can be provided, and as a result, the conversion efficiency to high frequency can be improved.

  According to the multi-beam klystron 10 of the present embodiment, the nose 31 (integrated nose 41) is projected along the circumference of a predetermined radius around the central axis 12, and the nose 31 (integrated nose) Since the nose 41) is provided with a plurality of beam holes 32 and slits 33, the inner surface of the outer peripheral wall 35 of the cavity 20 is not decentered at each position where each electron beam 13 of the nose 31 passes. The electric field strength can be made uniform.

  Since it is not necessary to decenter the inner surface of the outer peripheral wall 35 of the cavity 20, it is possible to perform lathe processing with concentric cores when machining parts, simplify the machining process, and reduce costs.

  Further, the slit 33 has a first slit 45 provided on the port 39 side of the nose 31 and a second slit 46 provided on the opposite side to the port 39 side of the nose 31, so that these first By separately adjusting the interval w1 between the slits 45 and the interval w2 between the second slits 46, the electric field strength at each position through which each electron beam 13 of the nose 31 passes can be arbitrarily adjusted. The strength can be made substantially uniform.

  Next, FIG. 9 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 nose 31 has a nose protrusion 49 that protrudes from the peripheral edge of each beam hole 32 on the tip surface side of the nose 31, that is, on the tip surface side facing the gap 42 of the integrated nose 41. Since the electric field concentrates on the tip end side of the nose 31, the nose projection 49 can reduce the area and reduce the discharge risk.

  In the above-described embodiment, the output cavity 23 to which the port 39 of the output unit 17 is connected has been described. However, the same applies to the input cavity 21 to which the port of the input unit 16 is connected.

  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.

10 Multi-beam klystron
12 Center axis
13 Electron beam
20 Cavity
30 Cavity body
31 Nose
32 Beam Hall
33 Slit
35 outer wall
39 ports
45 First slit
46 Second slit
49 Nose protrusion

Claims (3)

In a multi-beam klystron with a cavity to which a port for inputting or outputting high frequency is connected,
The cavity is
An outer peripheral wall is formed in a cylindrical shape centered on the central axis of the cavity, and a cavity body to which the port is connected to the outer peripheral wall;
A nose protruding along the circumference centered on the central axis in the cavity body from the end face side of the cavity body;
A plurality of beam holes provided in the nose so as to be arranged on a circumference around the central axis, respectively, through which an electron beam passes;
A multi-beam klystron comprising a slit provided in the nose. The said slit has the 1st slit provided in the said port side of the said nose, and the 2nd slit provided in the opposite side with respect to the said port side of the said nose. The described multi-beam klystron. 3. The multi-beam klystron according to claim 1, wherein the nose has a nose protrusion that protrudes from a peripheral edge portion of the beam hole on a tip surface side of the nose.

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