Measurements of Ar* and OH Number Densities in a High-Pressure Nanosecond Pulse Discharge

摘要

This work presents the results of temperature measurements and absolute, time-resolved number density measurements of excited metastable Ar atoms and OH radicals in mixtures of H_2, O_2, C_2H_4, C_4H_(10), and C_5H_(12) with argon excited by a repetitive nanosecond pulse discharge. The measurements have been made in a diffuse, double dielectric barrier discharge, plasma sustained between two liquid metal electrodes fully encapsulated within quartz. These reservoirs were placed on the top and bottom of the flow reactor channel, at initial temperature of 500 K and pressures ranging from 300 Torr to 700 Torr. Metastable Ar atom number density distributions in the discharge afterglow are measured by Tunable Diode Laser Absorption Spectroscopy (TDLAS), and used to characterize discharge uniformity. Temperature in the discharge-excited reacting flow is measured by Rayleigh scattering, and OH number density generated in the plasma is measured by Laser Induced Fluorescence (LIF). Two-photon Absorption Laser Induced Fluorescence (TALIF) is used to detect H atoms generated in the plasma, and TALIF measurements of absolute H atom number densities are underway. The results are compared with predictions of a kinetic model which is being developed for analysis of radical reaction kinetics at low temperatures and high pressures, for plasma assisted combustion applications.