Date of Award
Doctor of Philosophy (PhD)
Electrical and Computer Engineering
Z. A. Pour
Space stations., Solar cells., Space plasmas.
The International Space Station (ISS) has proven to be a great resource for observing spacecraft floating potential variations related to high voltage solar array operations in low Earth orbit (LEO). Measurements of the ionospheric electron density and temperature along the ISS orbit and variations in the ISS floating potential are obtained from the Floating Potential Measurement Unit (FPMU) suite of four plasma instruments (two Langmuir probes, a Floating Potential Probe, and a Plasma Impedance Probe) on the ISS. Recent data from the FPMU has revealed floating potential transients that occur during certain high voltage solar array operations. These transient variations are not reproduced by existing models and require further study to understand the underlying physical processes. In this work, a new model is developed, which incorporates the important plasma interactions with dielectric surfaces that are believed to be the cause of these transients. Lumped element modeling and particle-in-cell simulations are used to model the plasma interactions with the ISS surfaces, and an initial validation of the model is performed using FPMU data. The new model is successful at reproducing the behavior of the transient fluctuations, indicating that these transients can be attributed to spacecraft-plasma interactions.
Willis, Emily M., "Temporal evolution of the plasma sheath surrounding solar cells in low earth orbit and its effect on spacecraft charge collection" (2018). Dissertations. 159.