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An adapted capacitance manometer is a sensor composed of one fixed plate and one movable plate that is able to make accurate pressure measurements in a low pressure environment. Using detection circuitry, a change in capacitance between the two plates can be measured and correlated to a differential pressure. First, a high sensitivity manometer is produced that exhibits a measurable change in capacitance when experiencing a pressure differential in a low pressure space environment. Second, an accurate and precise detection circuit is identified to measure the change in capacitance. Both, the manometer and the detection circuitry, are tested separately and together to confirm accurate measurements when experiencing small pressure differentials. The manometer shows low sensitivity at the desired differential pressure range but reacts predictably when compared to simulations. The manometer also shows an unexpected correlation in capacitance change to temperature change. / Master of Science

Prior to launch, space craft instruments need to be tested in a relevant environment to prove operational functionality. Thus, we have developed an ion source to stimulate thermal plasma instruments in a vacuum chamber. This dissertation presents the mechanical design of the source, simulations of the potentials and charged particle trajectories in and around the source, and vacuum chamber measurements of the emitted ion beam. Once the ion source is understood, it is successfully used to test a typical ion instrument. Further aspects of the ion source, efficiency, thermionic filament emission, and collision frequencies are also discussed. / Doctor of Philosophy / Satellites have become a critical resource for business and governments. The study of the high edge of the earth’s atmosphere, where satellites operate, is difficult because the physics of this region is so complex. More measurements of the upper atmosphere are needed to understand exactly how it works and improve the computer models simulating the atmosphere. The instruments used to measure this region need to be validated before they are launched. This dissertation describes the design and testing of an ion source device that can produce charged particles in a very low pressure environment, such as a vacuum chamber, to create conditions similar to those an instrument would encounter in orbit. Computer simulations and physical tests of the source are presented, compared, and found to match. Finally, an actual satellite instrument is successfully validated with the source.