JPH04255642A - Microwave tube - Google Patents

Abstract

PURPOSE:To increase creeping discharge start voltage on the surface of a cylindrical ceramic. CONSTITUTION:At least one projection is formed on the vacuum side wall of a cylindrical ceramic 2 along the peripheral surface thereof between the anode electrode 4 and cathode Wehnelt electrode 5 of a stack type electron gun. In addition, a metal shield section 8 is so provided as to face the high voltage side of the aforesaid projection.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave tube, and more particularly to the structure of an insulating part of a stacked electron gun.

0002

2. Description of the Related Art In a conventional microwave tube stack type electron gun, as shown in FIG. and a cylindrical ceramic component 11 which also serves as an insulator are joined by brazing and constitute a part of the vacuum envelope.

[0003] The vacuum side wall surface of the cylindrical ceramic component 11 is provided with a protrusion on the circumference as shown in the figure. These protrusions are used to control creeping discharge that occurs along the ceramic surface by increasing the creeping length of the cylindrical ceramic component 11. In this figure, three protrusions are provided; Naturally, the dimensions and number of protrusions change depending on the potential difference between them.

0004

[Problems to be Solved by the Invention] In such a conventional structure, as the potential difference between the anode electrode 4 and the cathode-Wehnelt electrode 5 increases, the protrusion length l of the cylindrical ceramic component 11 is increased. Alternatively, it was necessary to increase the creepage length by increasing the number of protrusions. Therefore, there is a problem in that the size of the cylindrical ceramic component 11 increases as the anode voltage increases due to the large cathode current required as the power of the microwave tube increases.

[0005]

[Means for Solving the Problems] The microwave tube stack type electron gun of the present invention has a vacuum side wall surface of a cylindrical ceramic which serves as insulation between electrodes and a vacuum envelope at least along the circumference. It has a structure in which at least one metal shield component having one protrusion and a surface opposite to the high voltage side surface of the protrusion is installed on the low voltage side electrode.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a sectional view of a first embodiment of the invention. Cylindrical ceramics 1, 2, 3, anode electrode 4, cathode
Wehnelt electrodes 5 are alternately stacked and joined by brazing. In particular, one protrusion is provided on the circumference of the vacuum side wall surface of the cylindrical ceramic 2. A metal shield component 8 having a surface opposite to the high voltage side of this protrusion, that is, the surface on the anode electrode 4 side.
is brazed or welded to the Wehnelt support 9. As a result, the shield component 8 has the same potential as the cathode Wehnelt electrode 5.

[0007] Therefore, since the vicinity of the protruding surface of the cylindrical ceramic 2 has a value very close to the cathode potential,
The electric field strength at the brazed portion and the protruding portion between the cylindrical ceramic 2 and the cathode/Wehnelt electrode 5 is determined by the shield component 8.
It is much smaller than without it. Therefore, even if a potential difference that would cause a creeping discharge is applied between the cathode and the anode in the absence of the shield component 8, the electric field emission of electrons, which would cause the creeping discharge, from the brazed part is greatly reduced. Can be suppressed.

Furthermore, even if electrons are field-emitted from the brazed part, the electrons traveling along the protruding surface of the cylindrical ceramic 2 have low energy because the accelerating electric field is sufficiently weak, and when they collide with the ceramic surface, The emission ratio of the secondary electrons generated is less than 1, and the electrons spontaneously disappear as they travel along the surface of the protrusion, so they do not develop into creeping discharge.

FIG. 2 is a sectional view showing a second embodiment of the present invention. In this embodiment, a metal shield component 10
is brazed or welded to the cathode/Wehnelt electrode 5, and the effect is the same as that of the first embodiment shown in FIG.

FIG. 3 is a cross-sectional view of a third embodiment of the invention. In this embodiment, there are three protrusions of the cylindrical ceramic 11, and one metal shield component 8 corresponds to each of the two recesses between the protrusions.
It is brazed or welded to the Wehnelt support 9. The structure of this embodiment has the effect of increasing the individuality of the protrusion of the ceramic surface and increasing the number of shield parts 8 compared to the first and second embodiments.
It can be used up to even higher potential differences.

[0011]

Effects of the Invention As explained above, the present invention has a protrusion of the vacuum side wall surface of a cylindrical ceramic which serves as insulation and a vacuum envelope of a stacked electron gun of a microwave tube, and a metal structure connected to a low voltage electrode. By combining shield components, there is an effect that the starting voltage of creeping discharge can be increased by several tens of percent or more compared to a conventional example without a shield component, just by protruding the ceramic surface.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a first embodiment of the invention.

FIG. 2 is a sectional view of a second embodiment of the invention.

FIG. 3 is a sectional view of a third embodiment of the invention.

FIG. 4 is a sectional view of a conventional example.

[Explanation of symbols] 1, 2, 3, 11 Cylindrical ceramics 4
Anode electrode 5 Cathode/Wehnelt electrode 6 Wehnelt 7 Cathode 8, 10 Shield part 9 Wehnelt support

Claims (1)

[Claims] Claim 1: In a microwave tube having a stacked electric gun in which metal electrodes and cylindrical ceramics, which serve as insulation between the electrodes and a vacuum envelope, are alternately stacked and brazed, The vacuum side wall surface has at least one protrusion along its circumference, and
A microwave tube characterized in that at least one metal shield component having a surface opposite to the protruding high voltage side surface is fixedly provided on the low voltage side electrode.