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Proceedings Paper

Inhomogeneous charging characteristics of polycrystalline alumina surfaces
Author(s): T. Asokan; Tangali S. Sudarshan
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Paper Abstract

Electron-induced surface charging characteristics of sintered alumina were studied in relation to the polycrystalline features, such as (a) grain boundaries, (b) non-uniform distribution of grain size, and (c) orientation of grains, by adopting the scanning electron microscope `electrostatic mirror technique.' Significant variation in the charging characteristics of grains and grain boundary regions were not observed for bombardment with low energy (< 8 keV) electrons corresponding to secondary electron yield ((delta) ) > 1. Interestingly, for higher energies (> 8 keV) corresponding to (delta) < 1, the grain boundary regions were found to charge more negatively than the grains. The electrostatic mirror studies reveal that (1) the mirror image formation is not possible at high density defect zones, (2) the size of the mirror images, formed at one location varies significantly from that formed at another location, due primarily to the variation in the defect prone grain boundary volumes and, (3) the size of the image, formed on the grain, varies from that formed on another, due to variation in the crystallographic orientation of the grains. The results suggest that alumina undergoes inhomogeneous charging under electron bombardment.

Paper Details

Date Published: 1 May 1994
PDF: 4 pages
Proc. SPIE 2259, XVI International Symposium on Discharges and Electrical Insulation in Vacuum, (1 May 1994); doi: 10.1117/12.174669
Show Author Affiliations
T. Asokan, Univ. of South Carolina (United States)
Tangali S. Sudarshan, Univ. of South Carolina (United States)


Published in SPIE Proceedings Vol. 2259:
XVI International Symposium on Discharges and Electrical Insulation in Vacuum
Gennady A. Mesyats, Editor(s)

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