Spectroscopy Diagnosis Of OH Radical In Ar/H₂O Discharge Plasma

In this paper,the emission spectra of OH radical in ultraviolet band?A²?⁺?X²??and near infrared band?Vibration rotational absorption transition of the first overtone??”=0??'=2??have been studied by means of emission spectroscopy and cavity ring-down spectroscopy.,respectively,and the spectral intensity,number density and rotation temperature of OH radical under different discharge conditions have been discussed.In the first part,the spectrum of OH radical produced in the discharge of Ar/H₂O plasma jet is studied by means of emission spectroscopy.The rotation temperature is estimated with the help of Lifbase spectrum simulation software.It is concluded that if the operating gas and carrier gas flow rates velocity are invariant.With the increase of discharge voltage,the spectral intensity of OH radical increases gradually,and when the discharge voltage and gas flow rate are constant,the peak value of the spectral line strength of OH radical appears near 2100 ppm when the H₂O content in the discharge system increases,and then decreases continuously.The rotation temperature of OH radical increases with the increase of discharge voltage or discharge frequency,while the rotation temperature decreases with the increase of working gas velocity.In the second part,the spectrum of the ground state transition of OH radical produced in Ar/H₂O plasma dielectric barrier discharge plasma is studied by cavity ring-down spectroscopy.Considering the wavelength range of the diode laser and the intensity of OH radical,four lines of P₂?5.5?f and P₂?6.5?f in X²?_1/2 and P₁?5.5?e and P₁?6.5?e in X²?_3/2 were selected.Under the condition of high reflectivity of 99.974%,it is found that the number density of OH number increases with the increase of discharge voltage or frequency.The number density of OH number increases first and then decreases with the increase of gas pressure.The rotation temperature of OH radical is determined by Boltzmann diagram method,and it is found that the rotation temperature increases with the increase of discharge voltage.