Characterization of atmospheric pressure microwave plasma in N_2/O_2/H_2O

摘要

A coaxial microwave plasma source operated at 2.45 GHz in atmospheric pressure N_2/O_2/H_2O mixtures has been studied. A global kinetic model provides the electron density and temperature, the amplitude of the electric field and population densities for a given absorbed power and gas temperature. A two-dimensional model of the plasma source based on Maxwell's equations has been applied to obtain the distribution of the electric field and the absorbed microwave power density for given plasma density estimated from the global model and experimental findings. Optical emission spectroscopy has been applied to observe the OH (A-X, 309 nm) emission intensity. The measured OH intensity at increasing H_2O admixture agrees qualitatively with the calculated change of the OH density. The rotational temperature has been determined from simulated spectra of the N_2~+ first negative system to be in the range 6500 ± 1000 K.