Optical study of OH radical in a needle-plate DC corona discharge

摘要

In this study, the emission spectra of OH (A(2)Sigma -> X-2 Pi, 0-0) and N-2 ( C-3 Pi(u) -> B-3 Pi(g)) emitted from the high-voltage DC (direct-current) corona discharge of N-2 and H2O mixture gas in a needleplate reactor are successfully recorded at one atmosphere. The relative vibrational populations and the vibrational temperature of N-2 (C, v ') in negative DC corona discharge are determined. The effects of discharge voltage, input power and added oxygen on the relative populations of OH (A(2)Sigma) radicals and N-2 ( C-3 Pi(u)) molecules in negative DC corona discharge are investigated. It is found that the relative populations of OH (A(2)Sigma) radicals and N2 ( C-3 Pi(u)) molecules increase with increasing the discharge voltage and the input power and decrease with increasing the added oxygen. The emission spectra produced by positive DC corona discharge are also studied for comparing with negative DC corona discharge. However, the emission spectrum of OH ( A(2)Sigma -> X-2 Pi, 0-0) is not obtained in positive DC corona discharge, only the emission spectrum of N-2 (C-3 Pi(u) -> B-3 Pi g) is observed. The effects of discharge voltage and input power on the relative populations of N-2 (C-3 Pi u) molecules in positive DC corona discharge are also investigated. The relative populations of N-2 (C-3 Pi(u)) molecules increase with increasing the discharge voltage and the input power. The main involved physicochemical processes have been discussed.