Design and preliminary characterization of the magnetically stabilized gliding arc discharge

Abstract

Supersonic combustion is characterized by high flow speeds and consequently, short residence times for ignition, flame stabilization and reaction completion. Hydrocarbon fuels that are of major interest due to their high density and endothermic decomposition properties have longer ignition and combustion times than that of hydrogen. Hence, there is a crucial need to dramatically shorten the ignition time and to enhance the combustion and flame stabilization. From the viewpoint of chemical kinetics, combustion is a chain process with two limiting reactions: chain-initiation and chain-continuation. Plasma as a source of free radicals and ions can significantly reduce the chain initiation time.The best plasma discharge system should generate non-equilibrium plasma with high concentration of active species and intermediate (better adjustable) temperature, high enough to support chain continuation reaction. The discharge that suits the above description is the Gliding arc (GA) plasma discharge. This unique discharge has relatively high plasma density (1012-1014 cm-3), power and operating pressure in comparison with other non-equilibrium discharges; higher electron temperature (> 1 eV), relatively low gas temperature (< 3000K) and good chemical selectivity in comparison with thermal discharges.The GA discharge however, can be very unstable for study purposes. Hence, we develop a novel gliding arc system that is driven and stabilized by a magnetic field. In this thesis, we discuss the design and preliminary characterization of the stabilized magnetic gliding arc (MGA) discharge. It is confirmed from our measurements and estimations that the MGA is a non-equilibrium GA discharge that can be coupled with a counter flow burner for ignition and combustion studies.%%%%M.S., Mechanical Engineering – Drexel University, 2007