Oval sheet beam electron gun

Abstract

The invention belongs to an oval sheet beam electron gun, which is used with a travelling wave tube, a backward wave tube and the like. The oval sheet beam electron gun comprises a shell, an electric heating wire in the shell, a cathode component, a focusing electrode component and an anode, wherein an emitting surface of a cathode head of the cathode component is a plane, the focusing electrode component comprises a pyramidal focusing hole, and the anode is positioned at an output port of the shell and provided with an anode hole which is a cylindroid hole. The cathode head is made of lanthanum hexaboride, the emitting surface of the cathode head is modified into a plane, a pyramidal hole with a rectangular axial section is used as the focusing hole, and the cylindroid hole is used as the anode hole, so that the oval sheet beam electron gun has the advantages that the oval sheet beam electron gun is simple in structure and convenient in processing, the precision is easy to be guaranteed, devices are easy to be miniaturized, the production cost is low, current emitted by the cathode head is high in density, operation frequency of the devices and current density of electron beams can be improved effectively, the electron gun is high in output efficiency and long in service life, and the like. The defects of complex structure, low current density and unevenness of the electron beams, high evaporativity and short service life of the cathode in operation at high temperature, and the like in the prior art can be overcome.

Description

technical field [0001] The invention belongs to the field of vacuum electronic devices, in particular to an elliptical strip-shaped injection electron gun, which is especially suitable for matching with traveling wave tubes, return wave tubes and the like. Background technique [0002] With the development of vacuum electronic technology, when the traditional "O" type vacuum electronic device develops to millimeter wave and higher wave band, due to the increase of operating frequency, the size of the device will become smaller and smaller, and the processing will change accordingly. In addition, due to the limitation of the space charge effect, the increase of the current density of such devices is restricted, and their power capacity is bound to be limited, which leads to a sharp decline in the overall performance of the device as the operating frequency increases. Compared with the traditional "O" type vacuum electronic devices, the ribbon injection vacuum electronic devic...

AI Technical Summary

Problems solved by technology

Although this electron gun has the advantages of high power output, small size and compact structure in the W wave band when it is used for the strip injection klystron, it also has the following: one. The strip injection electron gun of this invention adopts the Pierce method design The emitting surface of the cathode is a concave cylindrical surface, so when the size of the cathode is small, the current density of the electron beam generated by the concave cylindrical cathode will become uneven; second. To match the concave cylindrical cathode, The elliptical gradient focusing pole adopted not only has a complex structure, but also when it is used for focusing the electron beams emitted by the small-sized cathode, the trajectories of the edges of the electron beams will cross, resulting in poor laminar flow; third. As the frequency increases, the size of the electron gun becomes smaller. The electron gun has higher requirements on the accuracy of the cathode emitting surface, the focusing pole and the elliptical cone hole of the anode head. The processing of the ellipse cone hole is difficult, which is not conducive to the miniaturization and Increase in working frequency; Fourth, this type of electron gun usually uses barium and tungsten materials as cathodes, which not only emit low current densities, such as: the operating temperature of tungsten (W) cathodes is 2500K-2700K, and the emission current density is 0.26-1.5A / cm 2 ; The working temperature of the oxide cathode ((Ba·Sr·Ca)O) is 900K~1000K, and the emission current density is 0.81~5.0A / cm 2 ; The working temperature of impregnated barium tungsten cathode (BaO-W) is 1000K~1200K, and the emission current density is 0.33~5.1A / cm 2 , and this kind of cathode works under high temperature conditions, the evaporation rate of the cathode is high, and the service life is short

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