Date of Award:
Doctor of Philosophy (PhD)
J. R. Dennison
J. R. Dennison
D. Mark Riffe
Eric D. Held
Jan J. Sojka
James S. Dyer
The charging of multilayer materials as related to the charging of spacecraft is one of the primary concerns related to activities in the space environment. To understand how multilayer materials undergoing electron bombardment charge, an in-depth study of energy-dependent material properties must be undertaken. These properties include the electron penetration depth, secondary electron emission, charge transport and electrostatic discharge. By using energy dependent models of these properties, along with the geometry of the system, multilayer models can be developed to predict the time evolution of the internal charge distribution. Using these models, the net surface potential and the measurement of electrode currents can be used to extrapolate information about the internal charge distribution.
The Utah State University Materials Physics Group, with the funding of NASA James Webb Space Telescope project, performed several tests to understand the charging of multilayer dielectrics in various configurations. By using the Surface Voltage Probe to measure the net surface potential, along with measured electrode currents, the internal charge distribution can be inferred by using the developed theory for multilayer materials.
Because each scenario requires a unique analysis, the theory of multilayer charging for a multilayer dielectric is outlined for four configurations defined as (i) surface layer deposition with grounded conductive layer, (ii) surface deposition with ungrounded conductive layer, (iii) conductive layer deposition with grounded conductive layer, and (iv) conductive layer deposition with ungrounded conductive layer. The results for these tests are outlined along with the fits given by the predictive models. The results of the tests show that knowledge of the energy-dependent electronic properties of the material, the energy of the incident electrons and the geometry of the system are all vital to predict the outcome of the given scenario. It is shown that for multilayer materials with an ungrounded conductive layer, electrostatic discharge occurs after the material charges past the breakdown limits of the material. These results can help to design, construct, and model already deployed spacecraft to mitigate and prevent detrimental spacecraft charging effects.
Wilson, Gregory, "The Internal Charge Evolution of Multilayered Materials Undergoing Mono-Energetic Electron Bombardment" (2021). All Graduate Theses and Dissertations. 8244.
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