S-band Left-handed Material Oscillator

The left-handed material is an artificially designed,subwavelength composite material based on a metal resonating element and has unique characteristics(for example,complex permittivity,negative magnetic permeability,negative refractive index,etc.)that are different from conventional materials.Since the birth of left-handed materials in 2000,the development of left-handed materials has been irrevocably led to major technological changes in areas such as information technology.Left-handed material has achieved significant achievements so far and was named by Materials Today as one of the 10 major breakthroughs of the past 50 years.According to these characteristics of left-handed materials,it has been widely used in the field of plane mirror imaging,electromagnetic stealth,vacuum electronic devices and other fields.In the field of electronic vacuum devices,foreignr esearchers have developed new types of oscillators based on left-handed materials,resistance wall amplifiers,and new ribbon-shaped radiation sources.These devices have shown higher power and efficiency than conventional devices.The advantages of vacuum devices,but a common disadvantage of these devices is the large size and the external power required is large,that is not conducive to implementation.In the face of ever-increasing demands,there is an urgent need to develop an electric vacuum device that is small-sized and can ensure higher power and efficiency.In this thesis,a left-handed material-based oscillator is proposed.Using the characteristics of strong resonance and high coupling impedance of the left-handed metal element,a slow-wave structure of the metal element is proposed.The longitudinal length of the device is reduced by filling dielectric and adjusting cycle length,and the miniaturization of the device is realized,and high power and high electron conversion efficiency are also guaranteed.The innovation of this thesis has the following aspects:1.The properties of negative permittivity of this metal unit structure are verified by using the S parameter extraction method.The HFSS simulation software is used to simulate the high frequency characteristics of the slow wave structure unit of left-handed materials.The results show that the system has high coupling impedance.2.By filling the dielectric,the phase velocity of the high-frequency field is reduced,thereby reducing the acceleration voltage of the electron injection,which reduces the volume of the external power supply required by the device,making the assembly of the device simpler.3.Applying this new type of slow-wave structure to the oscillator,the number of cycles and the coupling output structure are optimized,and the longitudinal length of the entire tube is maintained at about 140 mm,which is greatly reduced compared with the conventional oscillator.4.Design three kinds of different coupling the output of the oscillator,respectively for the rectangular waveguide output,the output coaxial magnetic coupling,the coaxial electric coupling output,including rectangular waveguide coupling output power,the biggest can reach 90 kW,electronic conversion efficiency of 37.5%;The output power of the oscillator with coaxial coupling output can reach 40-50 kW,the efficiency is 27%,and the electronic efficiency is lower than the rectangular waveguide coupling,but its transverse volume is smaller,which is more conductive to the miniatinization of the device.Paper finally also attempts to the phase velocity gradient method to improve the efficiency of the coaxial line coupling output oscillator,the simulation of peak power output increased from 40 kW to 48 kW,electronic conversion efficiency increased from 26.7% to 32.2%.