Award Date

1-1-2007

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical and Computer Engineering

First Committee Member

Robert A. Schill, Jr.

Number of Pages

165

Abstract

This Thesis reports theoretical and experimental evaluations of the critical components of the UNLV secondary electron emissions test stand. These components include: (1) a source of electrons, an electron gun, (2)methods and instrumentation to obtain a direct measure of electron current supplied by the electron gun, and (3) a position sensitive particle detector that is capable of detecting single electrons and that provides the spatial and temporal distribution of secondary electrons. The overall objective of this project is to study the properties of secondary electron emission and the conservation of charge in the secondary electron emission test stand. Secondary electron emission (SEE) can potentially lead to beam instabilities, material degradation and r.f. breakdown. The part SEE studios have deduced secondary electron yield by invoking a conservation of charge without the need to experimentally account for all measurables. In the spatial distribution studies of SEE, one may not invoke conservation of charge without some knowledge leading to all loss effects. An electron gun in the SEE test stand at UNLV directs the primary electron beam through a beam drift tube piercing the center of a particle position detector with controlling grid towards the sample under test. Secondary electrons emitted by the sample either drift freely or are drawn by a grid potential to the particle position detector. The particle position detector records the number of electrons and the locations of electron impact. Low primary beam currents are necessary in order to perform these measurements within the resolution of the detector. Because the detector surface is flat and finite in dimension, some loss to the chamber walls will result. Consequential SEE loss to the walls is not measurable in a noise environment even if the experimental apparatus (the SEE test stand) is isolated from the earth ground. A Faraday cup is used to monitor the primary beam current. The beam drift tube, grid, and sample currents are monitored and integrated to yield the number of charges collected by each component over rime. Each component of the detector assembly, such as grid, microchannel plates and the data acquisition card will be studied in detail in order to achieve an absolute measurement of the secondary electron emission.

Keywords

Charge; Conservation; Electron; Emission; Secondary; Stand; Test

Controlled Subject

Electrical engineering

File Format

pdf

File Size

2949.12 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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