Electrical and Computer Engineering ETDs

Publication Date

Summer 7-28-2026

Abstract

Photoionization is a key mechanism governing the formation and propagation of streamer discharges in air by generating electron-ion pairs ahead of the streamer front. Accurate and computationally efficient modeling of this non-local process is essential for reliable plasma simulations. However, the widely used Zheleznyak photoionization model relies on empirical assumptions and requires computationally expensive domain-wide integration.

This dissertation advances photoionization modeling in three ways. First, the classical integral model is enhanced by incorporating experimentally measured vacuum ultraviolet (VUV) emission spectra together with photoabsorption and photoionization cross-section data, enabling direct calculation of the photoionization source term as a function of pressure while reducing empirical assumptions. Second, a Fast Fourier Transform (FFT)-based spectral method is developed to solve the Helmholtz representation of the photoionization model in cylindrical coordinates using Discrete Cosine and Discrete Sine Transforms to satisfy physical boundary conditions. The proposed method maintains high accuracy while achieving speed improvements of approximately two orders of magnitude over conventional solvers. Finally, the spectral solver is incorporated into a finite-volume drift-diffusion plasma model for streamer discharge simulations, providing an efficient and physically grounded framework for large-scale, high-resolution plasma modeling.

Keywords

Photoionization, Photon, Absorption cross-section, Streamer, Positive Streamer, Spectral Methods, Discharge

Project Sponsors

U.S. Department of Energy

Document Type

Dissertation

Language

English

Degree Name

Electrical Engineering

Level of Degree

Doctoral

Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Mark Gilmore

Second Committee Member

Jane Lehr

Third Committee Member

Andrew Fierro

Fourth Committee Member

Jacob Stephens

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