Masters Theses

Abstract

"Flashover voltage, lifetimes, and switch performance of insulators utilizing thin and thick film electrodes were examined to determine the viability of using thin electrodes for reliable surface discharge switching. Gold, silver, and platinum were sputtered and screen printed onto AI2O3, TiO2, and a modified BaTiO3 (MBT), then tested at 1atm, 10-3 torr, and an insulating fluid, SF2. DC surface flashover results in air across all three insulators indicate a linear relationship between flashover voltage and electrode gap spacing between 0.5 and 3mm. Delay times of approximately 20ns with a corresponding jitter of 6ns were observed across all three insulators under triggered flashover. Insulators in air with sputtered electrodes had lifetimes of approximately 5 for DC flashover and 40 for triggered flashover. Screen printed TiO2 and MBT had DC flashover lifetimes of approximately 10 in air, and 3 in vacuum and SF2. Screen printed TiO2 and MBT had triggered flashover lifetimes of greater than 200 in air, and less than 3 in vacuum an SF2. Screen printed AI2O3 had DC and triggered flashover lifetimes of greater than 200 in air, vacuum and SF2. Insulator failure during DC flashover was determined to be due the formation of a conductive channel between the anode and cathode. Formation of the channel was attributed to insulator thermal and dielectric properties and the presence of vaporized electrode species in the gap region during flashover"--Abstract, page 2.

"This paper presents a method for enhancing the switched charge in ferroelectric cathodes through the application of internal metal electrodes. Electric field and potential distributions of the internal electrode configuration are presented and correlated to the observed enhancements of switched charge. Electrostatic modeling predicts an enhancement of over 450% in the switched charge with optimal placement of the internal electrodes. Initial experiments qualitatively validate the model, and modeling of a ferroelectric cathode with large grid spacing to dielectric thickness ratios (a/d) indicates that charge densities comparable to conventional ferroelectric cathodes with a/d ratios of 1 are possible"--Abstract, page 44.

Advisor(s)

Huebner, Wayne

Committee Member(s)

Anderson, H. U. (Harlan U.)
Waddill, George Daniel

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Ceramic Engineering

Publisher

University of Missouri--Rolla

Publication Date

Fall 2000

Journal article titles appearing in thesis/dissertation

  • Surface Switching Characteristics of Variable Permittivity Dielectrics with Thin Electrodes
  • Method for the Enhancement of Switched Polarization in Ferroelectrics

Pagination

ix, 73 pages

Note about bibliography

Includes bibliographical references.

Rights

© 2000 Eric Joseph Carleton, All rights reserved.

Document Type

Thesis - Restricted Access

File Type

text

Language

English

Thesis Number

T 7811

Print OCLC #

45687511

Electronic OCLC #

1079364902

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