The Research Of Short Millimeter-Wave Traveling Wave Tube With High Harmonic

THz wave is electromagnetic wave which is between short millimeter and infrared wave. Terahertz sciencetechnology has been widely used in military,communications,detection and other fields because its band has a unique advantage. However, the application of THz technology is limited by lacking terahertz source with miniaturization size and high power.In this paper, according to the theory of unrelativistic electron beam can produce high harmonic wave, we designed a new type of terahertz source--high harmonic traveling wave tube. The feature of the device is that electron beam modulated by the input signal and then the space phase of electronics will be form clusters by folding,and it also can select and amplify specific high harmonic signal while suppress other harmonic signals. This device driven by mature millimeter-wave signal source. High harmonic signal is amplified in the radiation section and inspired by high harmonic current.The study of the main content in this paper as follows:1. We studied high frequency and loss characteristic of the folded waveguide slow wave structure. One-dimensional nonlinear theory of the folded waveguide was introduced. We designed modulation and radiation section and analyzed the beam-wave interaction in this two section.2. The input/output devices and attenuator of the folded waveguide structure was researched. The Voltage standing wave ratio of Transitional waveguide and input/output window was simulated with HFSS simulation software.3. We studied by theoretical and simulated the short millimeter-wave traveling wave tube with high harmonic by using simulation software. Finally,we has assembled the whole tube.Simulated high frequency characteristic of the modulation and radiation section by HFSS simulation software,and obtained the structure parameter of the slow-wave structure. On this basis,we continued to simulate calculation about loss characteristic of slow-wave structure. To simulate the whole tube by using PIC model of CST electromagnetic simulation software,to optimize the best beam working voltage and the most appropriate length of the modulation and drift tube. The simulation result show that:the working voltage of the beam is 18.4k V,current is 120 m A,the frequency of the input signal is 46 GHz and input power is 300 m W,the output signal in radiation section is 138 GHz and the output power is 144.5W. The output signal is 3 times of the input signal,and the output spectrum is very pure,and there is no other harmonic or oscillation signal component. Proving that high harmonic traveling wave tube can produce high harmonic and amplify it, and also instruction that the tube is a promising source of terahertz devices.