Date Approved

9-27-2022

Embargo Period

9-29-2022

Document Type

Thesis

Degree Name

M.S Electrical and Computer Engineering

Department

Electrical and Computer Engineering

College

Henry M. Rowan College of Engineering

Advisor

Robert Krchnavek, Ph.D., P.E.

Committee Member 1

Wei Xue, Ph.D.

Committee Member 2

John Schmalzel, Ph.D., P.E.

Committee Member 3

Jie Li, Ph.D.

Keywords

dielectric, superconductor

Subject(s)

Electric lines--Superconducting

Disciplines

Electrical and Computer Engineering

Abstract

Gaseous helium is often considered as an alternative to liquid nitrogen to cool modern high-temperature superconducting cables in support of increased power capacity and/or reduction of required cable size. However, the small size of helium molecules and relatively poor dielectric strength of helium gas create challenges which limit the usefulness of modern cable dielectrics. Continuous dielectric coatings have been considered as an alternative to traditional lapped tape dielectrics to support gaseous helium refrigerants, but unmatched thermal contraction between the coating and cable components would induce failures due to mechanical stress. Composite materials have been considered as a means of matching rates of thermal expansion to that of superconducting cables while retaining excellent withstanding against strong electric fields. Polyimide/silicon dioxide nanocomposites are a promising candidate for this application and are examined as such in this work. Nanocomposite films of various filler concentrations up to 7% were produced and tested for their dielectric strength at both room temperature and approximately 90 K. Despite a slight reduction in dielectric strength with increased nanoparticle concentrations at room temperature, the results suggest that polyimide provides ample dielectric strength as a composite matrix in superconducting cable dielectrics.

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