The Research Of An X-Band Novel Slow-wave Structure For The High Power Traveling-wave Tube

The traveling-wave tubes(TWTs) are kinds of important electronic devices. These are microwave amplifiers that are used immensely in satellite communications and military radar systems. TWTs mainly include coupled-cavity traveling-wave tubes(CC-TWTs) and helix TWTs. Though the traveling wave tubes based on coupled-cavity slow wave structure have much smaller bandwidth than the helix TWT, however, for many radar applications, they are absolutely sufficient. Coupled-cavity slow-wave structure(SWS) is made of metal. They have a lot of advantages such as strong strucyural and good heat dissipation. Due to the excellent performance in power capacity, the high power coupled-cavity TWT are still very interesting research subjects.In this paper, we present the design of a high power SWS: X-band CC-TWT with a novel ridge-loaded staggered single-slot rectangular slow wave structure. Compared with the traditional Hughes-type circular coupled cavity TWT, a series of rectangular coupled cavity TWT were investigated because they have the advantage of easy fabrication and assembly, which is considerably practical in design of millimeter wave TWT. Compared with the existing double-slot rectangular coupled cavity TWT, our designed TWT has the advantage in coupled impedance and electron efficiency, which has the potential of miniaturization in CC-TWT. In this paper, the main work are as follows:1. The dispersion and coupling impedance of the new SWS has been simulated so that the influence of various structural dimensions of high-frequency characteristics can be summarized. The simulation model of the X-band CC-TWT with input and output ports, including two transition waveguides and several severs. The severs are used to suppress the oscillations caused by reflected waves, therefore simulation results show that the entire high-frequency characteristics of voltage standing wave ratio(VSWR) less than 1.6 in the operating frequency range.2. We show the simulation result by using 3-D PIC code in Computer Simulation Technology(CST) particle studio to investigate the interaction of beam and wave in the CC-TWT. The number of cells that we used in CST particle studio is 1065672 and the number of particles involved in the simulation is 340136. The simulation results show that it can produces output power over 20 kW and its gain over 38 dB when the beam current is set to 5 A and the beam voltage is adjusted from 25.95 to 26.95 kV. Meanwhile, its electronic efficiency is up to 17 percent at the 8.6-9.5 GHz frequency range.3. we fabricated the X-band CC-TWT including the slow-wave line, the input and output structure, the window according to results of the study process. its cold test results show that VSWR of the entire high frequency structures is less than 2 at the working frequency range of 8.6-9.5 GHz.