A slow-wave structure suitable for multi-electron injector return-wave tubes in the millimeter-wave terahertz band

Abstract

The invention provides a slow-wave structure suitable for a multi-electron injection return wave tube in the millimeter-wave terahertz frequency band. The slow-wave structure can be applicable to the millimeter-wave terahertz frequency band, and belongs to the field of microwave vacuum electronic devices. The structure of the present invention uses two fixedly connected metal grid teeth to form a unit ridge, and a plurality of unit ridges are periodically arranged to form a slow wave structure formed by ridges and rectangular waveguides. This structure combines the structural characteristics of ridge waveguides, rectangular waveguides and trapezoidal lines to form a A new type of slow wave structure. The parallel structure of this slow-wave structure is similar to the multi-conductor slow-wave structure. Its advantage is that the coupling impedance is easy to adjust. Through appropriate parameter design, a larger coupling impedance can be achieved; the coupling impedance decays faster in the direction away from the grid surface. The lower the electron beam, the larger the area of ​​the electron beam can be realized, and the higher output power can be realized, and its lateral size is not limited by the wavelength, and can be expanded arbitrarily.

Description

technical field [0001] The invention belongs to the field of microwave vacuum electronic devices, and in particular relates to a slow-wave structure suitable for a multi-electron injector return-wave tube in the millimeter-wave terahertz frequency band. The slow-wave structure can use a plurality of strip electron beams to work. Background technique [0002] As the core component of the Cherenkov electric vacuum device, the slow wave structure is an important place for the interaction between the electron beam and the electromagnetic wave. Because of the size co-transition effect, when the operating frequency of the device rises to the millimeter wave and terahertz frequency bands, the geometric size of the slow wave structure will decrease sharply, which greatly reduces the available current of the slow wave structure and makes processing difficult. Coupled with the reduction of coupling impedance and the shortening of wavelength, the effective charge amount of cluster clus...

AI Technical Summary

Problems solved by technology

Among them, the ridge waveguide slow wave structure such as figure 1 As shown, its bandwidth is wide, but the coupling impedance is low. The schematic diagram of the slow wave structure with two ridge waveguide units connected in parallel is shown in Figure 5 As shown, its structural dispersion curve is shown as Image 6 As shown, the upper cut-off frequency of the working mode Mode2 is the same as that of the non-working mode Mode1, and the lower cut-off frequency is different. Working between 180° and 280° phase shift per cycle will cause strong mode competition

It can be seen that when the ridge waveguide slow wave structure is connected in parallel, there will be many high-order strong competition modes, and the tube cannot work stably

Solving the mode competition requires shifting the operating frequency band in the direction of increasing phase shift per cycle, which results in smaller structures that cannot be processed

The schematic diagram of a rectangular single gate structure is shown in figure 2 As shown, it is the slow wave structure commonly used in millimeter-wave terahertz return wave tubes. Its coupling impedance attenuates sharply after leaving the grid surface. It can only work effectively when the electron beam is very close to the grid surface, and its lateral size is limited by the wavelength. , cannot be expanded arbitrarily, so cannot work in parallel

The schematic diagram of the trapezoidal line slow wave structure is shown in image 3 As shown, the front view of the multi-conductor slow-wave structure is as follows Figure 4 As shown, the coupling impedance of the two is high. After parallel connection, the existing modes are complex, and the basic characteristics of the dispersion of the parallel structure are similar to those of the ridge waveguide. The competition between the modes is strong, and it is impossible to work stably with multiple injections.

Therefore, the parallel connection of existing slow-wave structures either has low coupling degree or serious mode competition

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