Date of Award:
12-2022
Document Type:
Dissertation
Degree Name:
Doctor of Philosophy (PhD)
Department:
Physics
Committee Chair(s)
JR Dennison
Committee
JR Dennison
Committee
Jan Sojka
Committee
David Peak
Committee
Lee Pearson
Committee
Reyhan Baktur
Abstract
Radiation Induced Conductivity (RIC) is the change in conductivity of a material due to bombardment from incident high energy radiation. RIC has consistently been found to follow a standard power law relation, ππ πΌπΆ(π) = ππ πΌπΆ(π)αΈβ(π), between conductivity, ππ πΌπΆ and adsorbed dose rate, αΈ. ππ πΌπΆ(π) and β(π) are material dependent parameters. Previous RIC models were developed in the π β 0 limit. Now expanded models are developed in the low temperature limit (within a few ππ΅π of the effective Fermi level) by approximating the Fermi-Dirac equation within a few ππ΅π of the effective Fermi level. Derivations are based on seven density of states (DOS) models for highly disordered insulating materials: three monotonically decreasing models within the bandgap (exponential, power law, and linear) and two symmetric peaked models within the bandgap (Gaussian and delta function), plus a limiting case with a uniform DOS for each type.
In addition, temperature dependent RIC data is compiled from literature for five polymeric materials used commonly in spacecraft: KaptonTM (polyimide or PI), polyethylenes (PE, low density polyethylene or LDPE, high density polyethylene or HDPE), TeflonTM (polytetrafluoroethylene or PTFE), MylarTM (polyethylene terephthalate or PET), and fluorinated ethylene propylene (FEP). Comparisons are made between compiled data from the literature and Utah State University RIC data, along with pertinent discussion of the results with a focus on the relevance of structural phase transition temperatures on measured RIC values. The second part of this work addresses the serious dearth of pertinent RIC data available needed to make critical design decisions for spacecraft, namely for the current NASA Europa Clipper and Lander missions.
Checksum
ceda3cb9d7180c77856d170f276a2d15
Recommended Citation
Gillespie, Jodie, "Temperature Dependent Density of States Models and Compiled Data for Radiation Induced Conductivity" (2022). All Graduate Theses and Dissertations, Spring 1920 to Summer 2023. 8629.
https://digitalcommons.usu.edu/etd/8629
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