Electrical and Computer Engineering ETDs

Publication Date

2-29-1968

Abstract

A neutron source which produces high density pulses is useful, for example, in the simulation of an atomic blast or in neutron activation chemical analysis. Rather than forming pulses by deflecting the deuteron beam emitted from a continuous source of deuterons onto and off of a tritium target, it was decided to investigate the possibility of transient deuteron production. Proton sources were studied in place of deuteron sources because of the availability of hydrogen gas for experimentation. An experimental system was set up in which transient electrical discharges through hydrogen could take place. It was hoped that discharges could be induced which would provide information on proton current density. Such discharges demanded independent charge behavior and no secondary charge production. Experiment showed, however, that no data on proton behavior could be obtained with the existing system. In order to explain the outcome of these experiments and to lay a foundation for the study of pulse mode proton sources, several theoretical models of gaseous conduction were examined. Because it was desired to approximate the experimental configuration, the theoretical discharges considered were restricted to those involving one-dimensional charged particle flow between two plane-parallel electrodes at low pressure (1 torr). These models included inertia-limited conduction, several variations of mobility-limited conduction, plasma conduction, sheath-limited conduction, the glow discharge, and the arc discharge. In each case, an attempt was made to describe the transient behavior of the protons in the region of the cathode and to arrive at some estimate of maximum proton current density and pulse duration. The current in the external circuit was also derived so that the "efficiency" of the source in terms of proton current versus external current was indicated. The theoretical study indicated that the experimental discharges were probably copper vapor arcs instead of the necessary type of hydrogen discharges. Such arcs violate the assumptions on which the experiments were based and explain the nature of the experimental results. Comparison of the results obtained from the various models suggested that only the sheath-limited conduction model and the arc discharge appeared capable of providing high proton current densities (i.e., greater than a fraction of an ampere per square centimeter). The arc, however, is an even more prolific source of electrons than protons. Separation of the protons and electrons in an arc would again involve the space charge limitations inherent in the sheath-limited conduction model.

Document Type

Thesis

Language

English

Degree Name

Electrical Engineering

Level of Degree

Masters

Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Wayne Willis Grannemann

Second Committee Member

Ronald Rutt Mohler

Third Committee Member

Harold Dean Southward

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