JPS6028137A - Microwave tube - Google Patents

Abstract

PURPOSE:To obtain a microwave tube with an electron gun that can prevent the high disturbance of an electric orbit and can obtain a stable beam in the dual mode operation by dividing a current control grid into two or more grids that can apply various types of potential and arranging them on the same sphere. CONSTITUTION:A current control grid 3 and a screening grid 2 are formed with pyrolytic graphite and are spaced at intervals using insulator boron nitride 8. In addition, a cathode 1 and the screening grid 2 are insulated with boron nitride 9 and are spaced at intervals. Furthermore, an insulated layer 10 on the surface of the screening grid 2 and the control grid 3 is used to reduce the secondary electrons from the grids. The current control grid 3 is divided into 3a and 3b in the circumferential direction and potential can be applied to them independently. The dual mode operation is achieved by varying this divided control grid potential and the fine adjustment of the beam shape, diameter and current is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure of a grid electrode in a grid-equipped electron gun of a microwave electron tube.

A microwave electron tube consists of an electron gun section that injects and forms an electron/electron beam, a high-frequency circuit section that interacts with the electron beam and amplifies high-frequency power, a collector section that captures all of the electron beams after interaction, and a focusing section for the electron beam. A major component is the focusing device that maintains the

2 Normal to perform two types of output operation (dual mode) in which the microwave electron tube is operated in pulses.

A method is adopted in which a grid electrode is installed in front of the cathode to completely control the radiation current from the cathode. In recent years, microwave tubes and electron tubes have been required to obtain high-power, high-efficiency high-frequency electric radiation, and therefore require electron beams with high current density.Puerh mode operation type tubes are no exception to this. In an electron gun with a grid, when a positive potential is applied to the grid cage that controls the cathode surface placed close to the electron emitting surface of the cathode (all cathodes), some of the emitted electrons from the cathode are transferred to the grid. Collision results in heat loss. In order to reduce heat loss in this grid electrode, another grid gold film is placed between the current control grid and the cathode, which is kept at the same potential as the cathode in the operating state to prevent electrons from directly flowing into the current control grid. Also,
There is also a method in which these grids are covered with an insulator and placed directly on the cathode surface.

When designing a Puar mode electron tube, it is common practice to determine operating conditions such as beam voltage, beam current, and grid potential based on all standards for high-power operation, and then to determine the shape of each electrode. Normal Puar mode operation is realized by changing the potential between the cathode lattices and changing the current from the cathode by 1.

Therefore, in an operating state other than the operating mode set as a reference at the time of design, an electrostatic lens is formed due to the potential of the grid electrode, causing disturbance of electron trajectories. This disturbance in the electron trajectory causes a thermal problem when it collides with the body electrode and the high-frequency circuit near the high-frequency circuit, which also affects the stability of the tube.

An object of the present invention is to provide an electrode structure in which the grid of a grid-equipped electron gun of a dual-mode microwave tube can be arbitrarily divided and different potentials can be applied to each grid, and the electron emission area of the cathode can be controlled for each divided grid. It is to be.

According to the present invention, there is obtained a microwave electron tube equipped with an electron gun characterized in that the current control grid is divided into a plurality of parts that can apply different potentials and are arranged on the same spherical surface.

Examples will be explained below using figures.

Figure 1 shows the structure of a grid-equipped electron gun that integrates a jamb/grid and a current control grid. Further, FIG. 2 is a partially enlarged view of the cathode and grid in FIG. 1. Current control grid 3
The shield lattice 2 is made of pyrolytic graphite, and the spacing between the control grid 3 and the shield lattice 2 is made of polon nitride, which is an insulator. Ride 9 insulates and maintains spacing. Also, the insulating layer lO on the surfaces of the jamming grating 2 and the control grating 3 serves to reduce secondary electrons from the grating. A cross-sectional view of the control grid 3 at this time is shown in FIG.

In order to change the high frequency output with the electrode structure shown in Fig. 1, the potential of h1 control grid 3 is changed.
Lower the chamber height and reduce the beam current.

However, in this case, the shapes of the shielding grid 2 and the control grid 3 are usually designed based on high output.

The trajectory of the electron beam during the IJII force is disturbed by the electrostatic lens formed between the cathode 1 and the control grid 3. This turbulent electron beam collides with the body electrode 5 and the high frequency circuit 7, causing thermal problems such as heat loss and reducing the stability and efficiency of the tube. Especially when the high frequency Ial path is helix 7.

The helix may melt due to heat loss, so collision of the electron beam with the high-frequency circuit must be avoided at all costs.

Conventionally, in order to prevent this disordered electron beam from colliding with the Hesox circuit, an electrode 6 for shaping the disordered electron beam has been provided at the entrance of the helix circuit.

The beam shaping electrode 6 has an inner diameter smaller than the inner diameter of the helical and y-axis 7, and its length is determined by the degree of beam disturbance. If the beam disturbance is large, the length of the beam shaping electrode 6 and the tube 9 will naturally be long, and sufficient heat countermeasures must be taken.

An entire embodiment of a current control grid 3 according to the invention is shown in FIG.

The current control grid 3 is divided into two parts 3a and 3b in the circumferential direction so that a potential can be applied independently to each part. Puar mode operation.

This is achieved by changing the divided control grid potential. That is, during high output operation, a common potential is applied to the two control grids 3a and 3'b. On the other hand, during low output operation, the potential of the inner control grid 3b is discharged, and the potential of the outer control grid 3a is kept unchanged from that during high output.

Therefore, the electron beam during low power operation becomes a hollow beam on the cathode surface. According to this method,
The extraction of current from the cathode can be controlled only by the inner control grid potential, and a complete electron gun with a grid can be provided that can prevent large disturbances in electron trajectories and obtain a stable beam in Puar mode operation. The division of the control grid 3 is designed according to the magnitude of the low output.

By virtue of the invention, different potentials can be applied to each control grid 3, making it easy to finely adjust the beam shape, beam diameter, and beam current.

In addition, although the high frequency circuit is shown as a helix as an example, the invention is not limited to this and can be applied to other high frequency circuits. Furthermore, the number of grid divisions and the division method may be any number of divisions, such as nine divisions, depending on the shape of the base of the control grid.

[Brief explanation of drawings]

1] Fig. 1 is an axial sectional view of the electron gun with a grating, Fig. 2 is a perspective axial sectional view of the cathode and the lattice when the lattice of the electron gun with a lattice is made of pyrolytic graphite, and Fig. 3 is a cross-sectional view of a conventional lattice. FIG. 4 is a cross-section of blood and meat according to an embodiment of the present invention. 1... Cathode, 2... Shielding grating, 3... Control grid, 4... Beam forming electrode, 5... Body as pole, 6... Beam shaping electrode, 7-... Helix, 8...
・Insulating boron nitride for shielding grid and control grid,
9...Insulating boron nitride for cathode and shielding grid, 10...Insulating boron nitride for control grid. h? -Kuniichi 17ζ-

Claims (1)

[Claims] Electron gun, high frequency circuit, collector. In a microwave tube composed of an electron beam focusing device, a grid on the cathode surface of the electron gun that controls the radiation current from the cathode is divided into a plurality of parts to which different potentials can be applied, all of which are arranged on the same spherical surface. A microwave tube that makes things t￥f＠.