JPH08138563A - Electron gun for traveling-wave tube - Google Patents

Abstract

PURPOSE: To establish a method for assembling an electron gun, with which it is practicable to secure effectively the vibration resistance and durability of the gun even if it is constructed small. CONSTITUTION: An electron gun for a traveling-wave tube is equipped with a cylindrical support 1 to support a Wehnelt electrode 3 by the farther end 1B and an encapsulation tray member 2 which supports one end 1A of the support 1 while it is fitted in a cylindrical protrusion part 2A. One-side end face 1Aa of the support 1 is arranged flush with the protrusive end face 2Aa of the protrusion part 2A of the tray member 2, and a plurality of through holes 10 are provided at the peripheral side face of the fit part of these two members, support 1 and tray 2, and their end faces in joint are laser welded at the one-side end face 1Aa and the through holes 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for a traveling wave tube which is a microwave tube, and more particularly to an electron gun for a traveling wave tube having enhanced vibration resistance.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a traveling wave tube which has been used relatively often in the past. Traveling wave tube 5 shown in FIG.
1 includes a high frequency circuit 53 formed in a spiral shape, an electron gun section 52 coaxially mounted on the high frequency circuit 53, and a metal vacuum envelope (case) 51A accommodating these. .

6 to 7 show the electron gun unit 5 in FIG.
It is the perspective view and sectional drawing which partially expanded the case part of 2. In the traveling wave tube 51 shown in FIG. 5, an electron beam is formed by an electron gun unit 52 (not shown), and the high frequency wave and the electron beam introduced through an input line 56 while passing through a high frequency circuit (helix) 53. Interact with each other to amplify high frequencies. The amplified high frequency is taken out from the output line 57, and the interacted electron beam is captured by the collector 54. Reference numeral 55 is a focusing magnetic field device for focusing the electron beam in the center and allowing it to stably pass through the high frequency circuit (helix) 53.

In the electron gun section 52, reference numerals 58,
Reference numerals 59, 60 and 61 denote ceramic insulating cylinders. The ceramic insulating cylinders 58 to 61 form a vacuum envelope 51A portion of the electron gun portion 52, and one electrode (anode electrode) 62 made of metal is provided at both ends along the central axis.
The other electrode 64 is sealed by brazing so as to maintain vacuum tightness.

Here, reference numeral 65 indicates a Wehnelt electrode that narrows down the electrons emitted from the cathode electrode 67 into a narrow electron beam, and reference numeral 66 is a cylindrical support that supports the Wehnelt electrode 65 via the enclosing dish member 63. . Further, the anode electrode 62 controls the amount of electron beam by changing the potential between the anode electrode 62 and the cathode electrode 67. Further, reference numeral 71 indicates an exhaust pipe.

The inside of the traveling wave tube 51 is evacuated to a high vacuum level of about 10 ^-9 Torr through the exhaust pipe 71 during the manufacturing process, and then the exhaust pipe 71 is pressure-bonded and sealed. .

Further, in order to operate the traveling wave tube 51,
A voltage of several KV higher than the filament voltage of several V for heating the cathode electrode 67 and the cathode potential is applied to the anode electrode 62 and the helix 53. A potential lower than the helix potential by several KV is applied to the collector 54 in order to reduce power consumption. Here, since the case 51A has the same potential as the helix 53, it is common to operate the potential of the helix 53 as the ground potential. Therefore, the potentials of the cathode 67 and the collector 54 have a high negative potential with respect to the case 51A. Also, reference numeral 7
Reference numerals 2 and 73 denote insulating members such as silicon rubber for insulating the high voltage of the electron gun unit 52 and the collector 54.

In the structure of the traveling wave tube 51 of this type, in particular, the structure in which the electrodes of the electron gun section 52 are sandwiched by a plurality of ceramic insulating cylinders 58 to 61 to be brazed and sealed is as follows:
It has excellent vibration resistance and vacuum tightness, and has been used comparatively often from the past.

On the other hand, in response to the recent demand for downsizing, it is difficult for the electron gun section 52 to perform brazing work for downsizing. Therefore, downsizing is attempted while maintaining vibration resistance. Was one of the important issues.

6 to 7 show the electron gun unit 5 in FIG.
2 shows a conventional support structure for the Wehnelt electrode 65 inside. Here, the inner and outer diameters of the ceramic insulating cylinders 58 to 61 for downsizing the electron gun portion 52 are suppressed to be small, and as a result, the cylindrical support body 66 that supports the enclosing dish member 63 and the Wehnelt electrode 65 is reduced. Laser welding is used for welding. That is, if there is a spatial margin in the welded portion, resistance welding is used in which the welded portion is sandwiched by tweezers. However, since the electron gun portion 52 is downsized and there is no spatial margin, a laser is used. Welding is used. Reference numeral 74 is a laser welding nugget showing a welded portion by laser welding.

[0011]

However, in the joining by the laser welding, since the joining dish member 63 and the cylindrical support body 66 can be joined only at the end faces, the welding strength is insufficient and the vibration resistance is difficult. It was As a countermeasure for this, a method of increasing the laser output to increase the weld joint strength is conceivable, but there is a limit to increase the laser output because the thin member to be welded is melted.

A method for solving such inconvenience is disclosed in Japanese Unexamined Patent Publication
-82207 is disclosed. The essential points are shown in FIGS.

In FIG. 8, a plurality of recesses 85, 85 are formed around the joint, and the recesses 85 are irradiated with a laser, whereby the melted regions of the members 81, 82 to be welded are increased. , The welding strength can be improved.

In the conventional example of FIG. 9, the recess 85 in FIG.
An example is shown in which the is cut into a square shape.

However, in such a conventional example,
The wall thickness of the welded member must be thick enough to provide a recess. Therefore, when welding a thin welded member having a thickness of 0.3 [mm] or less, it is practically impossible to carry out the welding. It is possible.

For this reason, the cylindrical support body 66 has been reduced in size.
In the case of laser welding of a portion, the joining strength becomes insufficient in the above-described conventional example, and therefore, the laser welding portion is likely to be cracked by vibration or impact, and the cylindrical support body 66 for supporting the Wehnelt electrode is the traveling wave tube. A situation occurs in which the pipe axis is tilted. When such a situation occurs,
The electron beam emitted from the cathode 67 collides with the high frequency circuit section (helix) 53 to heat the high frequency circuit section. The heating of this high frequency circuit section (helix) 53
This causes the generation of gas, which causes a deterioration in the degree of vacuum in the sphere inside the traveling wave tube, which causes a problem that the function of the traveling wave tube is stopped. That is, there is an inconvenience that the durability is reduced due to the miniaturization.

[0017]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electron gun for a traveling wave tube, which is capable of improving the inconvenience of the conventional example, and effectively ensuring the vibration resistance and durability of the electron gun even if the electron gun is downsized. To aim.

[0018]

According to a first aspect of the present invention, a cathode electrode that emits electrons, a Wehnelt electrode that forms electrons emitted from the cathode electrode into a narrow electron beam, and electrons extracted from the cathode electrode are used. An anode electrode for controlling the amount is provided, and the Wehnelt electrode is supported by a cylindrical support body, and the cylindrical support body is equipped with an enclosing dish member for supporting the cylindrical support body in a cylindrical protruding portion in a fitted state. In the electron gun, the one end surface of the cylindrical support and the protruding end surface of the enclosing tray are set on the same plane, and a plurality of through holes are provided on the side surface of the fitting portion of the cylindrical support and the enclosing tray. A configuration is adopted in which one end surface of each of these cylindrical supports and the joint end surface of the plurality of through-hole portions with the enclosing tray are welded by laser welding.

According to a second aspect of the invention, a cathode electrode that emits electrons, a Wehnelt electrode that forms electrons emitted from the cathode electrode into a narrow electron beam, and an anode electrode that controls the amount of electrons extracted from the cathode electrode And a Weinert electrode is supported by a cylindrical support member, and the cylindrical support member is fitted in a cylindrical protruding portion at a central portion of the cylindrical support member. The one end surface of the convex support and the projecting end surface of the enclosing tray are formed by the same concave and convex end surface in which relatively large irregularities are continuous, and the cylindrical support at each peak and each valley bottom of the same concave and convex end surface. The encapsulation dish and the enclosing plate are welded by laser welding.

According to the third aspect of the present invention, the concavo-convex identical end surface is a sinusoidal concavo-convex identical end surface.

This aims to achieve the above-mentioned object.

[0022]

[Operation] A cylindrical support member that supports the Wehnelt electrode at the other end, and an enclosing dish member that supports one end of the cylindrical support member by fitting them in a cylindrical protrusion formed in the center in advance. Since the fixing point of is fixed in two places along the central axis, unlike the case of fixing only the end face in the conventional example, it sufficiently responds to vibration from any direction. be able to.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

1 and 2, reference numeral 1 indicates a cylindrical support, and reference numeral 2 indicates an enclosing dish member. The cylindrical support 1 and the enclosing dish member 2 are the improved versions of the cylindrical support 66 and enclosing dish member 63 disclosed in FIGS. 5 to 6 in the above-mentioned conventional example.

This will be described in more detail. Cylindrical support 1
Has a function of holding the Wehnelt electrode 3 forming a part of the electron gun at the other end 1B. This cylindrical support 1
Is connected to the enclosing dish member 2 with one end thereof fitted in the central portion of the enclosing dish member 2. The enclosing dish member 2 is formed in a disc shape, and has a cylindrical protruding portion 2A that fits and supports one end of the cylindrical support 1 described above in a central portion thereof. Further, the periphery of the enclosing dish member 2 is supported by a ceramic insulating cylinder forming an electron gun.

One end face 1Aa of the cylindrical support 1 and the projecting end face 2Aa of the cylindrical projecting portion 2A of the enclosing tray member 2 are set to be flush with each other. The cylindrical support 1 and the enclosing dish member 2
On the side surface of the fitting portion of the
Is provided.

Then, one end portion 1 of these cylindrical supports 1
The joint end faces of the plurality of through holes 10 of A with the enclosing dish member 2 are welded by laser welding at predetermined intervals. At the one end face 1Aa of the cylindrical support 1,
It is welded to the enclosing dish member 2 at 10 places. Also,
At four peripheral through-holes 10 provided on the side surface of the fitting portion between the cylindrical support 1 and the enclosing tray member 2, the arrow A in FIG.
Laser light for welding is irradiated from the direction, and the irradiated portion is welded.

Since laser welding can be performed even in a narrow space where conventional welding tweezers for resistance welding cannot be inserted, it can be effectively used for integrating members in miniaturization. In the present embodiment, welding is performed by irradiating the end face joint portion of the cylindrical support 1 and the joint portion exposed on the cylindrical side surface with laser from the tube axis direction. Reference numeral 14 represents a nugget formed by laser welding. The plate thickness of the cylindrical support 1 and the enclosing dish member 2 is about 0.3 mm, and the size of the nugget 14 depends on the laser output. It is set to about 0.6 mmφ).

As described above, according to this embodiment, the end face 1Aa of the one end of the cylindrical support 1 is laser-welded to the enclosing tray member 2 in the same manner as in the conventional example, and particularly, the cylindrical support 1 is used. Laser welding will also be carried out at four surrounding through-holes 10 provided on the side surface of the fitting portion of the enclosing dish member 2. Therefore, both fixing points are four surrounding points and two fixing points along the central axis. Since it is set by dividing into two, it is possible to sufficiently cope with vibration from any direction unlike the case of only the end face in the conventional example, and because it uses laser welding, it is compact Therefore, according to this embodiment, even when the electron gun is downsized, the vibration resistance and durability of the electron gun can be improved more than in the conventional case. Equipment The electron gun can be obtained.

Next, another embodiment will be described with reference to FIGS.

In another embodiment shown in FIGS. 3 to 4, the end face (end face) of one end 11A of the cylindrical support 11 is formed.
1Aa and the projecting end surface 12Aa of the cylindrical projecting portion 12A of the enclosing dish member 12 are formed with a relatively large undulating continuous same end surface 20, and each peak 21 and each valley bottom 22 of this uneven same end surface. The present invention is characterized in that the cylindrical support 11 and the enclosing dish member 12 are welded by laser welding.

In this case, in this embodiment, the concavo-convex identical end surface 20 is formed by a sinusoidal concavo-convex identical end surface. Further, in this embodiment, the fixing by laser welding at the valley bottoms of the same concavo-convex end face 20 functions in the same manner as the fixing by laser welding at the four through-hole portions in the surroundings in the embodiment of FIG. 1 described above. It has become. The other structure is the same as that of the embodiment shown in FIG.

In this way as well, in addition to the same effects as the embodiment of FIG. 1 described above, the fitting portion between the cylindrical support 11 and the enclosing tray member 12 is particularly short and laser welding can be performed. This is effective when a through-hole having the same size is not provided.

[0034]

As described above, according to the present invention, compared with the conventional laser welding only in the circumferential direction in the plane, the laser welding points are provided in a dispersed manner in the tube axis direction. The stress is dispersed and the vibration resistance is improved against the impact and vibration in the direction perpendicular to. As a result, the Wehnelt electrode is not tilted or decentered with respect to the tube axis even if shock or vibration is applied to the traveling wave tube, so that a stable beam transmission characteristic can be obtained, which is an unprecedented excellent electron gun for a traveling wave tube. Can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing a joint portion between a cylindrical support for supporting Wehnelt electrodes and an enclosing dish member in an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a joint portion between the cylindrical support body and the enclosing dish member disclosed in FIG.

FIG. 3 is a perspective view showing a joint portion between a cylindrical support for supporting Wehnelt electrodes and an enclosing dish member in another embodiment of the present invention.

FIG. 4 is a partial cross-sectional view showing a joint portion between the cylindrical support member and the enclosing dish member disclosed in FIG.

FIG. 5 is a partially omitted sectional view showing an example of a traveling wave tube incorporating an electron gun in a conventional example.

FIG. 6 is a perspective view showing a joint portion between a cylindrical support member for supporting Wehnelt electrodes and an enclosing dish member in the conventional example shown in FIG.

FIG. 7 is a cross-sectional view showing a joint portion between a cylindrical support member and an enclosing dish member in the conventional example disclosed in FIG.

8A and 8B are explanatory views showing a joining portion between a cylindrical support for supporting a Wehnelt electrode and its supporting member in another conventional example, FIG. 8A being a sectional view thereof, and FIG. (A)
FIG.

FIG. 9 is a cross-sectional view showing a modified example of FIG. 8A in a conventional example.

[Explanation of Codes] 1 Cylindrical support 1A One end 1Aa One end face 1B Other end 2 Encapsulation dish member 2A Cylindrical protrusion 2Aa Projection end face 3 Wehnelt electrode 10 Through hole 62 Anode electrode 65 Wehnelt electrode 67 Cathode electrode

Claims (3)

[Claims] 1. A cathode electrode for emitting electrons, a Wehnelt electrode for forming electrons into a narrow electron beam emitted from the cathode electrode, an anode electrode for controlling the amount of electrons taken out from the cathode electrode, and the Wehnelt. A traveling wave equipped with a cylindrical support member that supports the electrode at the other end, and an enclosing dish member that fits and supports one end of the cylindrical support member in a cylindrical protrusion formed in the center in advance. In a tube electron gun, one end face of the cylindrical support and the projecting end face of the cylindrical protruding portion of the enclosing dish member are set on the same plane, and the fitting portion between the cylindrical supporting body and the enclosing dish member is set. A plurality of through-holes are provided on the peripheral side surface of the cylindrical support body, and thereafter, one end portion end surface portion of these cylindrical support members and a joint end surface portion of the plurality of through-hole portions with the enclosing dish member are welded by laser welding. Features and Electron gun for a traveling wave tube. 2. A cathode electrode for emitting electrons, a Wehnelt electrode for forming electrons into a narrow electron beam emitted from the cathode electrode, an anode electrode for controlling the amount of electrons taken out from the cathode electrode, and the Wehnelt. A traveling wave equipped with a cylindrical support member that supports the electrode at the other end, and an enclosing dish member that fits and supports one end of the cylindrical support member in a cylindrical protrusion formed in the center in advance. In the electron gun for a tube, the end surface of one end of the cylindrical support is aligned with the projecting end surface of the cylindrical protruding portion of the enclosing dish member, and each end surface is made into a concavo-convex identical end surface formed by concavo-convex. An electron gun for a traveling wave tube, characterized in that the cylindrical support member and the enclosing dish member at each peak and each valley bottom of the same end surface of the concavo-convex shape are welded by laser welding. 3. The electron gun for a traveling-wave tube according to claim 2, wherein the concavo-convex identical end surface is a sinusoidal concavo-convex identical end surface.