A Terahertz Backward Wave Oscillator Based On The Metal Wire Slow-wave Structure

Terahertz radiation refers to electromagnetic radiation,whose frequency range is from 0.1 to 10 THz and the wavelength range is from 3 um to 3 mm.The frequency of terahertz wave is between the millimeter wave and infrared,radio wave and light wave.As a new frontier science,terahertz technology has been used in many fields,such as the security check,environment monitoring,aerospace,terahertz communication,nondestructive testing,materials science,medical imaging,researching extensively by scientists around the world.As a precondition of the exploitation of THz frequency band,how to efficiently generate a stable THz signal is a critical factor that has limited evolution of THz device.At present,the backward wave tube,also known as backward wave oscillator,is considered as the most promising device to produce THz radiation wave,having the characteristics of miniaturization,wide electronic tuning and low cost.And slow-wave structure is the core part of the backward wave oscillator,whose main function is exchange the energy between the electrons in electron beam and the electromagnetic field,which is the most important part that influent the performance of backward wave tube and various parameters.Therefore,a suitable slow-wave structure is very critical for high frequency system of backward wave tube.In this paper,we design a kind of backward wave oscillator with new metal wrap-wire slow-wave structure,operating at 0.3 THz,make its have the novel structure on the whole,the characteristics of low cost,easy to assemble,in performance with high output power and coupling impedance work,low voltage and low current density,etc.This paper also introduces in detail the structure of the design process.In order to reflect the winding back wave tube of good performance,this article also designed the output and the matching of the backward wave pipe structure,after using 3-D electromagnetic Simulation software CST(Computer Simulation Technology)to the overall structure of the Simulation,and gets the optimal by optimizing the test parameters of hot and cold cavity.In cold-chamber simulation,we obtained the typical parameter,such as dispersion curve,coupling impedance,the strength and distribution of electric field and S-parameters.And in terms of heat-chamber,the heat-parameters,such as the output power and energy change trend are obtained.In addition,the backward wave tube can also be applied to different ways of electron emission,such as the traditional hot-cathode electron gun and pseudo-spark discharge,and the influence of different current density on the output power was analyzed in this paper.Finally,with the electrical condition of operating voltage of 1.2 k V,current density of 94 A/cm2 and the current size of 50 mA,the novel backward wave tube with the wire-wrap slow-wave structure can product output power over 154 mW and electronic tuning bandwidth more than 24 GHZ,operating at 335 GHZ.The research result for the development of terahertz source device has potential application value.