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Proceedings Paper

Characteristics Of A Pulsed, Liquid-Metal Field Emission Source For Use In Fast High-Current Switches
Author(s): Michael J. Coggiola; Steve E. Young
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Paper Abstract

Liquid metal ion sources (LMIS) of the type used for ion beam lithography can also be used to produce large pulses of electrons via field emission. These sources typically consist of a small capillary through which a liquid metal is forced. The application of a voltage between this capillary and an extraction anode causes the liquid metal to form a sharp cone. When the intense field at the tip exceeds the threshold for field emission, a large electron current flows from the tip to the anode. The production of this electron pulse results in the rapid heating of the liquid-metal tip, leading to an explosive pressure increase, and a collapse of the tip. As the field is restored, the tip reforms, with a resultant self-pulsing mode of operation. The pulse repetition rate, the average current, and the current per pulse are all functions of the metal composition, emitter geometry, and applied diode voltage. These characteristics are reported for a variety of conditions, and show that a single emitter tip can produce current pulses in excess of 50 amperes, with a rise time of a few nsec, and a width of 5-50 nsec. Repetition rates vary between 10 Hz and 20 kHz. In addition to the observed electron emission, optical radiation is also produced. The dispersed visible spectrum shows predominantly emission from neutral, atomic species presumably excited by electron impact in the gas phase.

Paper Details

Date Published: 6 April 1988
PDF: 8 pages
Proc. SPIE 0871, Space Structures, Power, and Power Conditioning, (6 April 1988); doi: 10.1117/12.943649
Show Author Affiliations
Michael J. Coggiola, SRI International (United States)
Steve E. Young, SRI International (United States)

Published in SPIE Proceedings Vol. 0871:
Space Structures, Power, and Power Conditioning
Raymond F. Askew, Editor(s)

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