Reactive Oxygen And Hydrogen Species Generation In Radio Frequency Atmospheric Pressure Plasmas PDF Download

This thesis presents a novel, asymmetrical atmospheric pressure plasma jet, that uses air as its working gas, operating in the kilohertz range. The plasma system is designed to be mobile, easily set-up in many environments and has variable controllability, such as voltage, airflow and electrode position. The initial body of work presented in the thesis relates to the design and development of the atmospheric pressure plasma jet used throughout the bulk of the thesis. The key components of the atmospheric plasma jet are introduced. Electrical measurements of the plasma were also preformed and showed that the plasma operated electrically in two modes, the so called noisy and quiet modes. Optical emission spectroscopy was preformed on the plasma jet and showed that the emission spectrum of the jet was complex, containing emissions from many species, both molecular and atomic. These species included but were not limited to atomic species of nitrogen, oxygen and hydrogen and molecular emissions from N2, O2 and OH. In addition to this, it is possible to control the emission intensities from these species by varying the control parameters of the plasma jet such as voltage, airflow and electrode distance. The observed emission spectra were noticed to be lacking in any optical features due to emissions from nitric oxide, while it was believed to be the case that the plasma jet should produce nitric oxide. To test this hypothesis the experimental method laser induced fluorescence was chosen as a means to probe or nitric oxide in the plume region of the plasma. Experimentally it was found that nitric oxide was present within the plume. In addition by again varying the control parameters of the plasma jet the absolute number density of nitric oxide within the plume of the plasma could be varied. Finally, two-photon absorption laser induced fluorescence is used to probe for atomic oxygen in the plume region of the atmospheric pressure plasma jet. Two photon absorption differs from the single photon method in that two photons are simultaneously absorbed by and used to excite the species under investigation, opening up the possibility to probe species with excitation energies that are difficult to reach using conventional lasers systems. Like, the case for nitric oxide, atomic oxygen was confirmed to be present within the plume, although it was not possible to determine an absolute number density. Likewise, by varying the control parameters a change in the trend in the intensity of the fluorescence was observed.