Elliptical ribbon beam electron gun

Abstract

The invention belongs to an elliptical ribbon beam electron gun matched with a traveling wave tube, a backward wave tube and the like. The elliptical ribbon beam electron gun comprises a housing, a heating wire disposed in the housing, a cathode module having a planar cathode head emitting surface, a focusing electrode module comprising a rectangular pyramid focusing hole and an anode located at the output port of the housing and having an anode hole being a cylindroid hole. The lanthanum hexaboride is taken as the cathode head, the cathode head emitting surface is changed to a plane, the rectangular pyramid hole having a rectangular shaft section is taken as a focusing hole, and the cylindroid hole is taken as an anode hole. The elliptical ribbon beam electron gun is simple in structure,convenient to process, easy to ensure precision, easy to miniaturize the device, low in production cost and high in current density emitted by the cathode head, can effectively improve the working frequency of the device and the current density of the electron beam, is high in output power of the electron gun and long in service life, and overcomes the defects that the structure is complex, the current density of the electron beam is not uniform, the evaporation rate of the operating cathode is high in a high-temperature condition and the service life is short.

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...

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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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