Study On Characteristics Of Low Power Microwave Micro-plasma Array Source

Microwave micro-plasma refers to the micro-plasma generated by low microwave power,and its discharge size is on the order of millimeters or micrometers.Micro-plasma has the advantages of good stability,high electron density and long life.The size of the microwave micro-plasma excited by a single resonator is too small to meet the larger area plasma applications.Therefore,it is of great significance to further research on the microwave micro-plasma array source.The microwave micro-plasma array source based on the microstrip resonators at2.45GHz and its characteristics are studied in this thesis.Firstly,according to the principle of microstrip resonator,a unit structure of microwave micro-plasma array source and a 13-unit linear array structure are designed using HFSS simulation software.Based on the coupled mode theory,the relevant structural parameters are optimized to obtain the S parameters,resonant frequency,field structure distribution of one-unit and13-unit microwave micro-plasma array source.Secondly,the 13-unit microwave micro-plasma linear array source was fabricated,and its S parameters were tested.Finally,an experimental system was established to study the influence of gas pressure and input power on the micro-plasma excitation,discharge intensity,discharge area,emission spectrum of the microwave micro-plasma array source under air and argon conditions.The electron temperature and electron density of the microwave micro-plasma array source are calculated with the double-line method and stark broadening method based on the optical emission spectrum.And the frequency spectrum of microwave micro-plasma array source before and after micro-plasma excitation are detected by a broadband double-ridged horn antenna and a spectrum analyzer.The simulated and experimental results show that the microwave micro-plasma array source has multimode resonant frequencies.In addition to the domain resonant frequency of 2.45GHz,there are other resonant frequencies of 5.65GHz,9.61GHz,11.8GHz,15.84GHz and 17.68GHz between 0Hz and 20GHz.Under the condition of argon,when the input power is 27.02W,2 units of the microwave micro-plasma array source are ignited;when the input power is 29.22W,5 units of the microwave micro-plasma array are ignited;when the input power is 32.28W,11 units of the microwave micro-plasma array are ignited;when the input power is reduced to 23.9W,the microwave micro-plasma array is extinguished.Based on the optical emission spectrum,the electron temperature is 0.6727e V（7803.51K）and the electron density is5.692×10¹⁷cm^-3.The detected frequency spectrum shows that the maximum power spectrum before and after the excitation of the microwave micro-plasma array source is 2.4715GHz and 2.221GHz respectively,which means that the frequency shifts250.5MHz.The work provides a reference for further research on the characteristics of microwave micro-plasma array source.