Optical emission spectroscopy measurements of quiescent atmospheric plasmas created via dielectric barrier discharge actuators

Generating an atmospheric plasma as a form of flow control is a relatively novel technique for controlling boundary layer losses, reducing drag, and increasing overall airflow efficiency of immersed bodies in fluids. One method for achieving flow control through the use of atmospheric plasma is via a pulsed-dc dielectric barrier plasma actuator. The goal of this work is to measure and calculate the plasma temperature and electron density of the atmospheric plasma generated via a pulsed-dc actuator and using optical emission spectroscopy (OES) in quiescent air conditions. Through the course of this research, a method to measure and characterize dielectric barrier discharge plasmas was developed and used to quantify them through an experimental test stand, Spectroscopic Shadowgraphic Atmospheric Plasma Experiment (SeSAmE). Through testing of the plasma actuators with optical measurement techniques such as spectrometry and shadowgraphy, the necessary data is obtained and used in calculating plasma parameters such as electron temperature and electron density and values consistent with those expected in the literature. The spectra were analyzed using the relative line method and an absolute intensity transition method to compute electron temperatures and number densities, mainly through use of the N2 second positive set of transitions. Electron temperatures are found to be on the order of 0.25eV with number densities on the order of 1.1x1017 /m3. These data are also used to compare with a, first principles, multi-physics code coupling a fluid model, a chemistry model, and an electrostatics model.