| This work examined the effect of ignition on thruster performance characteristics of a capillary discharge device. Early tests of the presented device, incorporating an exploding wire ignition, showed a strong dependence on the initial plasma conditions. The literature supported these findings for more basic laboratory capillaries, but the effect on a thruster device was unknown. An in-depth investigation of different ignition systems were conducted for a capillary discharge based pulsed plasma thruster. In addition to conventional wires, capillary discharges were ignited with low pressure gas and several different types of spark igniters. These methods were compared with each other and with newly developed computer models.;The viability of a capillary discharge based electrothermal pulsed plasma thruster as an in-space propulsion system was examined. Thruster performance levels, and their ability to fill a desired niche, which has historically shown rather poor efficiencies, have been explored. This work contains a background literature study, experimental setup and testing of a capillary design, and a comparison to performance models created by others. New techniques have been coupled with proven plasma diagnostics to investigate the internal plasma properties of the device. Visible-light spectroscopy techniques were developed to examine the time-resolved electron number densities at the exit. These measurements indicated that there may be a slower rate for recombination than previous expected. Novel thrust stand techniques were demonstrated, measuring thruster performance characteristics with a high degree of accuracy. It was found the ignition method plays a very small role in discharge characteristics. Electrode erosions was investigated and largely eliminated from the device. The research conducted here has not only increased the understanding of ignition effects, but also the basic physics, of capillary devices. |
