Laser Induced Fluorescence Characterization of Cusped Field Plasma Thrusters

Download or read book Laser Induced Fluorescence Characterization of Cusped Field Plasma Thrusters written by Natalia Adrienne MacDonald and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cusped field plasma thrusters are a recent development in electrostatic propulsion, aimed at improving operation in the low power regime. Several diagnostic techniques have been employed to characterize these discharges. The present study focuses on the use of laser induced fluorescence to map ion velocities throughout the plumes of several cusped field thruster variants. Laser induced fluorescence provides the opportunity to probe small plasma sources with high spatial resolution, and is particularly useful for studying plasma propulsion devices where hot, energetic and highly non-uniform environments can adversely affect intrusive probes. The first half of this thesis focuses on time-averaged laser induced fluorescence velocimetry for three cusped-field thrusters. While a time-averaged velocity diagnostic is adequate in determining overall performance, it cannot resolve the dynamics seen in oscillatory modes of thruster operation. The second half of this research focuses on the development of an advanced CW laser induced fluorescence diagnostic technique, capable of correlating high frequency current fluctuations to the resulting fluorescence excitation lineshapes. This method is validated using simulations and a 60 Hz xenon spectral lamp. It is then applied to an oscillatory mode of the diverging cusped field thruster. Results show that the positions of the ionization and peak acceleration regions in the thruster vary over the course of a discharge current oscillation, causing the ion velocities to fluctuate in time. This new method of time-synchronized CW laser-induced fluorescence will be invaluable for better understanding the dynamics of thruster operation as well as other quasi-periodic oscillatory discharges, in fields from combustion to materials processing, among others.