JP2007257990A - Microwave tube, and method of manufacturing anode pole piece electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein, although the electron beam orbit in an interaction part of an electron beam 10 emitted from a cathode electrode 1 is kept by a cyclic magnetic circuit comprising a permanent magnet 6 and a pole piece 7, then the beam is excessively narrowed down to increase repulsive force between electrons because generation of the magnetic field by the cyclic magnetic circuit is rapid, and the beam orbit is not stabilized, whereby the electron beam is resultantly increased in waving compared to a desired electron beam orbit and in beam diameter. <P>SOLUTION: An anode electrode is integrated with a pole piece to form an anode pole piece electrode 3, and the outer peripheral side and the inner peripheral side of the anode pole piece are formed of a magnetic material and a nonmagnetic material, respectively, whereby an immersion magnetic field to the side of an electron gun is intensified to smoothly focus the electron beam. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a microwave tube such as a traveling wave tube, particularly to a microwave tube in which focusing of an electron beam emitted from an electron gun unit is stabilized, and a method of manufacturing an anode pole piece electrode used in the microwave tube It is.

  In general, a microwave tube typified by a klystron or traveling wave tube (TWT) is such that an electron beam emitted from a cathode electrode of an electron gun is focused by an electric field generated by an anode electrode, a grid electrode, etc. Amplify or oscillate and extract microwave from output window. In addition, the electron beam that has finished the interaction is collected by the collector unit. At this time, a magnetic circuit is formed by a permanent magnet or an electromagnet between the electron gun portion and the collector portion so that the electron beam does not diverge and passes through the interaction portion in a desired beam trajectory. For example, in a traveling wave tube using a permanent magnet, an electron beam radiated from a cathode electrode is focused by an electric field generated by a grid electrode and an anode electrode, and further, a periodic magnetic field circuit composed of a pole piece and a permanent magnet is used in an interaction section. The electron beam trajectory is maintained.

  However, since the periodic magnetic field generated by the periodic magnetic field circuit consisting of a pole piece and a permanent magnet is steep, the electron beam is narrowed down too much and the repulsive force between electrons becomes strong, and the beam trajectory is not stable and the wave of the electron beam is large. There is a problem that the electron beam has a large beam diameter. An electron beam with an unstable trajectory has a higher probability of colliding with the interaction circuit at the interaction section, and lowers the efficiency of the microwave tube. In addition, if the allowable heat capacity of the interaction circuit is small, the interaction circuit may be damaged and the microwave tube may be damaged.

  Conventionally, as means for solving this problem, the amount of magnetization of the permanent magnet is adjusted so as to gradually increase the magnetic flux density in the periodic magnetic field circuit, or the magnetic flux density of the magnetic field circuit is adjusted by attaching an iron piece to the periodic magnetic field circuit. Or, in Patent Document 1, in the first to several pole pieces near the electron gun side of the periodic magnetic field circuit, a non-magnetic material called a guide ring is provided on the inner peripheral side of the pole piece, and an effective pole piece radius is set. A method is also known in which the electron beam focusing is stabilized by increasing the magnetic flux density on the central axis in the first part of the magnetic field circuit.

As described above, conventionally, the generation of the periodic magnetic field by the periodic magnetic field circuit is prevented from being steep, and the electron beam is stabilized.
Japanese Patent Laid-Open No. 06-5209

However, in the conventional method, the magnetic field is completely blocked from leaking to the electron gun portion, and until the electron beam enters the magnetic circuit, the electron beam is controlled only by the electric field by the grid electrode and the anode electrode. . Therefore, there is a problem that the ripple (swell) of the electron beam remains somewhat.
The present invention relates to a microwave tube that does not require adjustment of magnetic flux density and has a small electron beam ripple (swell), and that can achieve stable electron beam focusing, and a method of manufacturing an anode pole piece electrode used in the microwave tube The purpose is to obtain.

  A microwave tube according to the present invention includes an electron gun unit having a cathode electrode and an anode electrode, a periodic magnetic field circuit including a plurality of pole pieces and a plurality of magnets for focusing an electron beam emitted from the electron gun unit, An anode pole piece electrode in which a pole piece located at the boundary between the electron gun unit and the periodic magnetic field circuit and the anode electrode is integrated in a device having a collector that captures an electron beam focused by a magnetic field circuit. The material of the anode pole piece electrode is a magnetic body on the outer peripheral side and a non-magnetic body on the inner peripheral side.

  Further, the present invention provides an anode pole piece electrode manufacturing method in which a pole piece and an anode electrode, which are located at the boundary between an electron gun part and a periodic magnetic field circuit, are integrated. First and second non-magnetic bodies having an inner peripheral side divided into two in the axial direction, the first non-magnetic body on the periodic magnetic field circuit side and the magnetic body on the outer peripheral side of the anode pole piece electrode are joined by brazing, The mating surface of the brazed member with the second nonmagnetic material on the electron gun side is machined, and the machined brazed member and the second nonmagnetic material on the electron gun side are subjected to beam welding. Are joined together.

In the microwave tube of the present invention, the material of the anode pole piece electrode is made a magnetic body on the outer peripheral side, and the inner peripheral side is made nonmagnetic, and the electron beam is controlled by letting an immersion magnetic field leak into the electron gun section. Since the control is performed by the electric field and the magnetic field, stable electron beam focusing with less ripple (undulation) of the electron beam is obtained, and adjustment of the magnetic flux density of the magnetic field circuit becomes unnecessary.
In the anode pole piece electrode manufacturing method according to the present invention, the magnetic body on the outer peripheral side and the first nonmagnetic body on the inner peripheral side are machined after brazing and then beam-welded with the second nonmagnetic body. Therefore, the material on the outer peripheral side and the material on the inner peripheral side are joined with high accuracy without generating a gap, and the ultra-high vacuum necessary for the microwave tube is maintained. This provides stable electron beam focusing as calculated.

Embodiment 1
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional structural view of a microwave tube showing Embodiment 1 of the present invention. FIG. 2 is an enlarged cross-sectional view of an anode port piece electrode integrated to share the anode electrode and pole piece in FIG.
In the microwave tube of FIG. 1, the electron gun portion is composed of a cathode electrode 1, a grid electrode 2, and an anode electrode. However, since the anode electrode is shared with a part of a pole piece of a periodic magnetic circuit described later in the present invention, the anode electrode and the pole piece are integrated to constitute an anode pole piece electrode 3.

  Between the anode pole piece electrode 3 and a collector 9 which will be described later, an interaction circuit 5 of a high-frequency circuit made of a metal having a spiral shape or a ring shape is disposed along the radiation direction of the electron beam 10. The interaction circuit 5 is made of a metal such as molybdenum or tungsten, and amplifies and transmits an electron beam microwave. The interaction circuit 5 is held by an insulating support 4 made of BN (boron nitride) or BeO (beryllium oxide). A periodic magnetic field circuit composed of a plurality of cylindrical permanent magnets 6 and a plurality of cylindrical pole pieces 7 which are magnetized in the axial direction to a saturated state is disposed on the outer periphery of the insulating support 4. Yes. The permanent magnet 6 is supported by the insulating support 4 via the spacer 8. A collector 9 for capturing an electron beam focused by a periodic magnetic field circuit is disposed on the opposite side of the electron gun unit.

  In FIG. 2, the anode pole piece electrode 3 is a pole piece located at the boundary between the electron gun section and the periodic magnetic field circuit, that is, among the plurality of pole pieces of the periodic magnetic field circuit, the pole piece adjacent to the electron gun section is the anode electrode. They are integrated into a cylindrical shape. Further, the material of the anode pole piece electrode 3 is configured such that the outer peripheral side 31 is made of a magnetic material such as iron and the inner peripheral side is divided into two in the axial direction, so that the first nonmagnetic material 32 and the second nonmagnetic material are divided. The body 33 is made of a nonmagnetic material such as copper or copper-nickel alloy. The anode pole piece electrode 3 is set to the same potential as the ground.

Next, a method for manufacturing the anode pole piece electrode 3 will be described. The microwave tube must be joined to the outside air without any gap in order to keep the inside in an ultra-high vacuum. Therefore, first, the first nonmagnetic body 32 on the periodic magnetic field circuit side, that is, on the interaction circuit 5 side, is integrated with the magnetic body 31 on the outer peripheral side by brazing. Next, since the second non-magnetic body 33 on the electron gun side plays a role of focusing the electron beam by an electric field, the brazed outer peripheral-side magnetic body 31 and the first non-magnetic body 32 are more accurate. Must be joined. If there is dripping or the like due to a brazing material on the joint surface, which is a mating surface between the second nonmagnetic body 33 and the brazed outer peripheral side magnetic body 31 and the first nonmagnetic body 32, the second nonmagnetic body Since 33 cannot be bonded to the outer peripheral side magnetic body 31 and the first non-magnetic body 32 with high accuracy, the electron beam cannot be focused as calculated. Therefore, the outer peripheral side magnetic body 31 brazed and the second nonmagnetic body 33 of the first nonmagnetic body 32 and the second nonmagnetic body 33 are brazed to the second nonmagnetic body 33 by machining the shaving. The accuracy of the joint surface between the outer peripheral side magnetic body 31 and the first non-magnetic body 32 is increased. After that, the outer peripheral side magnetic body 31 and the first nonmagnetic body 32 brazed to the second nonmagnetic body 33 are joined by beam welding.
As described above, while satisfying the two conditions of the vacuum sealing and the accuracy of the joint surface, a part of the anode pole piece electrode 3 is made of a non-magnetic material, and the immersion magnetic field on the electron gun side is made larger than before, Stabilize the beam trajectory.

  Next, the operation of the microwave tube shown in FIGS. 1 and 2 will be described. By applying a voltage to the grid electrode 2 and the anode pole piece electrode 3, an electric field for extracting the electron beam 10 is generated, and the electron beam 10 is emitted from the cathode electrode 1. The electron beam 10 radiated from the cathode electrode 1 is focused by an electric field formed by the grid electrode 2 and the anode pole piece electrode 3, and is formed by a periodic magnetic field circuit composed of a permanent magnet 6 and a pole piece 7. Electron divergence is prevented by the magnetic lens action of the periodic magnetic field. Further, the electron beam 10 is amplified or oscillated by the high frequency power by the interaction circuit 5 of the high frequency circuit, and takes out the microwave from the output window. After the interaction, the electron beam 10 is captured by the collector 9.

  Here, by applying a voltage to the grid electrode 2 and the anode pole piece electrode 3, the electron beam emitted from the cathode electrode 1 is partly non-magnetic as described above. The electron beam is focused as an electron beam having a desired beam diameter with few undulations by being influenced by the magnetic field due to the periodic magnetic field circuit and the two electric fields due to the anode pole piece electrode 3. By doing so, the electron beam focusing can be performed more smoothly than the current situation.

FIG. 3 shows a comparison of the change in the magnetic field distribution due to the difference in material of the anode pole piece electrode 3, and A shows the case where a part of the anode pole piece electrode 3 is made of a non-magnetic material as in the present invention. B represents the magnetic flux density distribution of the periodic magnetic field circuit, and B represents the magnetic flux density distribution of the periodic magnetic field circuit when the anode pole piece electrodes 3 are all magnetic. In FIG. 3, the horizontal axis represents the axial distance Z (mm) of the microwave tube, and the vertical axis represents the magnetic flux density Bz (gauss).
As can be seen from FIG. 3, when the anode pole piece electrode 3 is all a magnetic material, the magnetic field is blocked so that the influence of the periodic magnetic field circuit does not reach the electron gun side, so that the generation of the magnetic field by the magnetic field circuit becomes steep. . For this reason, the convergence of the electron beam becomes steep, and the wave of the electron beam becomes large. On the other hand, when a part of the anode pole piece electrode 3 is made of a non-magnetic material, the influence of the magnetic flux density due to the periodic magnetic field is exerted on the electron gun side, and the fluctuation of the magnetic field becomes moderate. As a result, the force for converging the electron beam is gradually applied, so that the variation in the radial direction of the electron beam trajectory can be reduced and the undulation is reduced.

FIG. 4 shows the electron beam trajectory calculation results when the anode pole piece electrode 3 is all magnetic, and FIG. 5 shows the case where a part of the anode pole piece electrode 3 is made nonmagnetic as in the present invention. The electron beam trajectory calculation results are shown. As apparent from FIGS. 4 and 5, by applying a voltage to the grid electrode 2 and the anode pole piece electrode 3, the electron beam 10 radiated from the cathode electrode 1 is converted into the anode pole piece as in the present invention. When part of the electrode 3 is made of a non-magnetic material (FIG. 5), it can be seen that the wave of the electron beam 10 is small and the radius of the electron beam 10 is small.
There is no dimensional difference between FIGS. 4 and 5, and the only difference is the material of the anode pole piece electrode 3. In the model in which a part of the anode pole piece electrode is a non-magnetic material, the wave of the electron beam is smaller and the electron beam diameter is also smaller.

Here, the relationship between the magnetic flux density Bz shown in FIG. 3 and the electron beam radius R shown in FIGS. 4 and 5 will be examined a little. The electron beam 10 performs a spiral motion by the Lorentz force due to the magnetic flux density Bz. At this time, when only one electron is considered, the radius of rotation r of the electron is
r = mv / eBz (Formula 1)
However, m is the electron mass, v is the radial velocity of the electron, e is the elementary amount of electrons. Therefore, the radius of rotation r of the electron is smaller as the magnetic flux density Bz is larger. However, in an electron beam formed by collecting electrons, if the radius is too small, repulsion occurs due to repulsion between electrons. Therefore, if the magnetic flux density Bz is too large, the electron beam radius becomes large.
In FIG. 4, when Z = 10 to 15 mm, the magnetic flux density Bz is increased too rapidly, so that the electron beam is too narrowed and repulsion occurs due to repulsion between electrons, and the electron beam is rippled (swelled). Has occurred. On the other hand, in FIG. 5, since the magnetic flux density Bz at Z = 10 to 15 mm is suppressed to be smaller than that of FIG. 4, ripple (swell) is also reduced, and the electron beam diameter can be reduced.

FIG. 6 shows an enlarged and contrasted radius of the electron beam trajectory shown in FIGS. 4 and 5. The horizontal axis represents the axial distance Z (mm) of the microwave tube, and the vertical axis represents the electron beam radius. R (mm). In FIG. 6, C is the radius of the electron beam trajectory when a part of the anode pole piece electrode 3 is made nonmagnetic as in the present invention, and D is the electron when the anode pole piece electrode 3 is entirely magnetic. Indicates the radius of the beam trajectory.
As can be seen from FIG. 6, the electron beam undulation is smaller and the electron beam diameter is smaller in the model in which a part of the anode pole piece electrode is a non-magnetic material.
Therefore, according to the present invention, it is not necessary to adjust the magnetic flux density of the magnetic field circuit, and stable electron beam focusing can be obtained with less electron beam ripple.

Sectional drawing of the microwave tube by Embodiment 1 of this invention. The expanded sectional view of the anode pole piece electrode shown in Embodiment 1 of this invention. The figure which compares and shows the periodic magnetic field distribution of the microwave tube at the time of comprising Embodiment 1 of this invention and all the anode pole piece electrodes with a magnetic body. The figure which shows the electron beam orbit calculation result at the time of comprising all the anode pole piece electrodes with a magnetic body. The figure which shows the electron beam orbit calculation result in Embodiment 1 of this invention. The figure which compares and shows the electron beam orbit radius of the microwave tube at the time of comprising Embodiment 1 of this invention and all the anode pole piece electrodes with a magnetic body.

Explanation of symbols

1: cathode electrode 2: grid electrode 3: anode pole piece electrode 4: insulating support 5: interaction circuit 6: permanent magnet 7: pole piece 8: spacer 9: collector 10: electron beam 31: outer periphery of anode pole piece electrode Side 32: Inner peripheral side of anode pole piece electrode (first nonmagnetic material)
33: Inner peripheral side of anode pole piece electrode (second non-magnetic material)

Claims (5)

  An electron gun section having a cathode electrode and an anode electrode, a periodic magnetic field circuit composed of a plurality of pole pieces and a plurality of magnets for focusing an electron beam emitted from the electron gun section, and an electron beam focused by the periodic magnetic field circuit In a microwave tube having a collector for capturing, an anode pole piece electrode in which the pole piece located at the boundary between the electron gun section and the periodic magnetic field circuit and the anode electrode are integrated, and the material of the anode pole piece electrode is an outer periphery. A microwave tube characterized in that the side is a magnetic body and the inner peripheral side is a non-magnetic body.   The first and second nonmagnetic materials obtained by dividing the inner peripheral side of the anode pole piece electrode in the axial direction into two parts, and the first nonmagnetic material on the periodic magnetic field circuit side and the magnetic material on the outer peripheral side of the anode pole piece electrode are brazed 2. The microwave tube according to claim 1, wherein the second non-magnetic material on the electron gun side is joined to the joined member by beam welding.   The microwave tube according to claim 2, wherein the outer peripheral side magnetic body and the first nonmagnetic body that are joined by brazing are formed by machining the mating surface of the second nonmagnetic body 33.   The magnetic material on the outer peripheral side of the anode pole piece electrode is made of iron, and the non-magnetic material on the inner peripheral side is made of copper or a copper nickel alloy. A microwave tube as described.   In the anode pole piece electrode manufacturing method in which the pole piece located at the boundary between the electron gun section and the periodic magnetic field circuit and the anode electrode are integrated, the anode pole piece electrode is made of a magnetic material on the outer peripheral side and the inner peripheral side is the axis. Joining the first nonmagnetic body on the side of the periodic magnetic field circuit and the magnetic body on the outer periphery side of the anode pole piece electrode by brazing; Machining the mating surface of the prepared member with the second non-magnetic body on the electron gun side, and beam welding the machined brazing member and the second non-magnetic body on the electron gun side A method of manufacturing an anode pole piece electrode comprising the steps of bonding.

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