Electrical and Computer Engineering ETDs

Publication Date

5-2004

Abstract

An experimental system has been set up that allows for the measurement of secondary electron yield (S.E.Y.) values as a function of time and beam energy. In these experiments, measured S.E.Y. values vs. incident electron beam energy of Poco Graphite, Titanium, and Copper varied greatly with time and energy. However, measured S.E.Y. values were still within the range of values given in the published literature.

Published values of S.E.Y. for materials of interest vary greatly from source to source. The discrepancy in this data appears to be due to various factors including the following: surface conditions, surface contamination, i.e. oxidation layers and adsorbed gases, measurements techniques, cleaning processes. and primary electron beam currents.

It is hypothesized that thermal energy deposited to the samples by the electron beam affects S.E.Y by heating the surface locally. thereby changing the local surface condition (e.g. adsobates, oxide layer, etc). This thermal effect appears to vary somewhat from material to material. New temporally resolved S.E.Y measurements over a range of energies for various materials, as well as data on the effects of baking, are presented.

This thermal transient could possible be another source for discrepancies m S.E.Y. values found in the literature. These new S.E.Y. measurements show that yield is time dependent and that one value for yield at a specif1c energy is unrealistic.

Sponsors

AFOSR grant number F49620-02-1-0067

Document Type

Thesis

Language

English

Degree Name

Electrical Engineering

Level of Degree

Masters

Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Mark Gilmore

Second Committee Member

John Gaudet

Third Committee Member

Edl Schamiloglu

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