In this work, experiment investigations and simulation studies of a waveguide-based microwave plasma source operated at 2.45 GHz in atmospheric pressure helium gas are presented. The plasma source has been designed in...In this work, experiment investigations and simulation studies of a waveguide-based microwave plasma source operated at 2.45 GHz in atmospheric pressure helium gas are presented. The plasma source has been designed in conjunction with a gas spectrograph as a speciation analysis tool. Emitted He spectra are observed for gas flow rates between （0.2-1） L/min and microwave power in the range （15-150） W. The results obtained demonstrate maximum excitation temperature of about 3800 K and gas temperature of about 2000 K. Mixtures containing small amounts of mercury atoms are considered and the resonant emission of Hg atoms at 253.56 nm is detected. The spectroscopic measurements are completed with a collisional radiative model delivering the electron density and temperature, the amplitude of the electric microwave field, and the population of the excited atomic states for a given absorbed power and gas temperature, The electromagnetic field distribution in the plasma source is obtained by solving Maxwell＇s equations. Electric field strength of several 10^5 V/m is obtained that agrees well with the results of the collisional radiative model. The calculated and measured line intensity ratios of He spectral lines agree within 300/0-40%.展开更多
文摘In this work, experiment investigations and simulation studies of a waveguide-based microwave plasma source operated at 2.45 GHz in atmospheric pressure helium gas are presented. The plasma source has been designed in conjunction with a gas spectrograph as a speciation analysis tool. Emitted He spectra are observed for gas flow rates between （0.2-1） L/min and microwave power in the range （15-150） W. The results obtained demonstrate maximum excitation temperature of about 3800 K and gas temperature of about 2000 K. Mixtures containing small amounts of mercury atoms are considered and the resonant emission of Hg atoms at 253.56 nm is detected. The spectroscopic measurements are completed with a collisional radiative model delivering the electron density and temperature, the amplitude of the electric microwave field, and the population of the excited atomic states for a given absorbed power and gas temperature, The electromagnetic field distribution in the plasma source is obtained by solving Maxwell＇s equations. Electric field strength of several 10^5 V/m is obtained that agrees well with the results of the collisional radiative model. The calculated and measured line intensity ratios of He spectral lines agree within 300/0-40%.
