The Generation And Spectroscopic Measurement Of OH In Plasma

Plasma is widely used in various fields such as waste gas treatment,surface modification,medical sterilization and biological breeding.Plasma diagnostics are the basis for understanding plasma properties and optimizing plasma applications.Spectroscopy is the main method of plasma diagnosis.Hydroxyl(OH)radical spectroscopy is often used to diagnose atmospheric plasma.The concentration of OH and its changes are important basis for monitoring the generation and evolution of atmospheric plasma.In this paper,the atmosphere,water vapor and mixed gas of water vapor are used as parent molecules,and the parent molecules are excited by glow discharge and ultrashort laser pulse filament to generate plasma.Plasma emission spectroscopy and midinfrared laser absorption spectroscopy are used to study plasma Generation and evolution of OH radicals.In glow discharge plasma,high-energy electron collision and dissociation of water vapor molecules is the main way to generate OH.When the OH concentration is low,the change trend of OH concentration measured by emission spectroscopy and absorption spectroscopy is consistent.When the concentration of OH in the discharge plasma is relatively high,the chemical reaction of OH with other components leads to obvious differences in the evolution trends of the emission spectrum and absorption spectrum intensities.In laser-induced atmospheric plasma,the OH emission spectrum intensity first increases and then decreases with the increase of atmospheric pressure due to the combined influence of the OH generation mechanism and the laser-induced atmospheric chemical reaction.Limited by the chemical activity of OH radicals,no absorption spectra of OH radicals were observed in laser-induced atmospheric plasma.In this paper,the generation of OH radicals in atmospheric plasma was studied by using multi-component parent molecules,variable gas pressure,and various excitation methods,and the evolution of OH radicals was monitored by collaborative emission spectroscopy and absorption spectroscopy,and the formation of OH radicals was preliminarily obtained.and evolution mechanism to provide a reference for the generation and diagnosis of atmospheric plasma based on OH radical spectroscopy.