Date of Award

12-2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Engineering Physics

First Advisor

Glen P. Perram, PhD

Abstract

Optical Emission Spectroscopy (OES) is an increasingly relevant technique in plasma diagnostics due to its inherent non-invasive nature and simple application relative to other popular techniques. In this work, common OES techniques are combined with novel methods, developed here, in an effort to provide comprehensive OES techniques for stationary and supersonic air microwave discharges. To this end, a detailed collisional-radiative model for strong atomic oxygen lines has been developed and used to identify the importance of often overlooked mechanisms including cascade emission and metastable excitation. Using these results, a combined argon actinometry technique was developed which makes use of the two strong oxygen triplets (777 nm and 844 nm) as well as the common N2/N2+ method in order to make simultaneous experimental estimates of gas temperature, dissociation fraction, electron temperature and electron density in a medium pressure synthetic air microwave discharge. Finally, a similar technique is proposed and tested in a supersonic flowing air microwave discharge which shows promise for rapid spatial imaging of electron temperature and ionization fraction in high Mach plasma flows.

AFIT Designator

AFIT-ENP-DS-20-D-016

DTIC Accession Number

AD1124111

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