| The coaxial resonant cavity has the characteristics of small size and high Q value,which can make the electric field concentrated and thus achieve rapid local heating or low-temperature plasma generation at low power,and has a wide range of applications in the fields of（microwave）ignition of automobile engines,microwave plasma torches and microwave drills.In this thesis,based on the coaxial microwave heating structure,the multi-physics field simulation optimization design of microwave drill bit and small microwave plasma torch is completed by using HFSS and COMSOL simulation software,and the preliminary experimental verification is realized.The research includes electro-magnetic optimization design of coaxial heating structure with high electric field strength at low power;multi-physics field coupling simulation of electromagnetic field and tem-perature field during micro-zone heating and microwave plasma excitation;experimental verification of coaxial resonant cavity microwave drill and microwave plasma based on low power microwave solid state source.Specific contents include:（1）Electromagnetic simulation design of coaxial microwave heating structure.The mi-crowave drilling cavity was designed based on the principle of quarter-wavelength coaxial resonant cavity,and the inner conductor with conical structure was used to optimize the size of the inner and outer conductors of the cavity and the coupling structure to improve the tip field strength of the coaxial microwave heating struc-ture.（2）Multi-physics field simulation of coaxial microwave heating structures.Simulation and analysis of electromagnetic thermal phenomena in microwave drilling process using COMSOL Multiphysics software to predict its temperature distribution.（3）Coaxial resonant cavity microwave drilling experimental study.After determining the model for processing and testing,the cavity reached S11of-15d B at a resonant frequency of 2.45GHz;the experimental platform was built to drill objects such as soda lime glass,edible chicken leg bone and duck skull,and the experimental results were good.In response to the impedance mismatch found in the experiment,the experimental setup is modified using a frequency-adaptive microwave solid-state source,which provides a new idea to simplify and promote the integration of microwave drilling devices.Finally,the potential possibility of applying microwave drilling to surgical procedures is explored and verified by simulation calculations of electromagnetic radiation and temperature fields.（4）Experimental study of coaxial resonant cavity microwave plasma torch.Firstly,the cavity structure of the microwave plasma torch was simulated for electromagnetic and fluid fields,and the electromagnetic characteristics of the three-tube double res-onance and the flow direction and flow rate of the working gas entering the cavity were analyzed;the experimental platform was built and the whole,skim milk and goat milk were pretreated using the microwave plasma torch,and the experimen-tal results showed that this approach is expected to detect more information in the spectral detection. |
