Study On Terahertz Two-stage Staggered Slow-Wave Structure

Recently, the terahertz (THz) science and technology has drawn much attention and many demonstrated application, because of infinite potential in application of science, such as in communication, radar, remote imaging, electronic warfare, nondestructive testing and other fields. However, the lack of high power terahertz radiation source and the simple structure, the practical application of terahertz technology was limited. In recent years, vacuum electronic devices have rapid development, and with micro-fabrication technology combining with micro vacuum electronic devices, the operating frequency is close to even to 1THz. Compared with the terahertz semiconductor devices, vacuum terahertz radiation source has the advantages of high efficiency.In order to improve the interaction efficiency and output power, a novel type of two-stage slow wave structure(SWS), based on half-period-staggered double grating arrays, has been proposed for terahertz oscillator. The slow wave structure has two-dimensional structure with the same focusing system.First, dispersive characteristics of slow-wave structure was simulated and the output property of the BWO and TWT were calculated by numerical method. Secondly, the transition structure and the connecting waveguide between the two SWS were designed, and the principle of operation was analyzed. The transmission losses of the whole RF structure S21>-10.5dB and the reflection parameter S11<-16dB are achieved in 295GHz-320GHz. Finally, the process of the beam-wave interaction of structure was simulated with two-electron beam, and the voltage parameters were optimized using PIC software. The results show that the output power may reach 14.6W with 18mA operating current. Because of relative high efficiency, the RF structure shows the application potential for terahertz vacuum electronic sources.