The use of SEM to investigate the effect of an electron beam on the optically-visible flashover treeing of MgO ceramic
This paper introduces the use of a scanning electron microscope (SEM) to evaluate the insulation property of insulators under electron bombardment. An SEM may be used not only to observe a surface image but also to provide a fine electron beam for charging an insulator surface simultaneously. The di...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Springer Science+Business Media
2007
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/8676/1/AGUS_-_Journal_of_Materials_Science_2007.pdf http://irep.iium.edu.my/8676/ |
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| Summary: | This paper introduces the use of a scanning electron microscope (SEM) to evaluate the insulation property of insulators under electron bombardment. An SEM may be used not only to observe a surface image but also to provide a fine electron beam for charging an insulator surface simultaneously. The distribution of electric field created by the surface charging can be developed by a simple model. The increase of electric field at the surface may exceed a critical value to experience a surface breakdown/optically-visible flashover. The insulation property is evaluated by measuring the period of charging/ electron bombardment, which is needed to initiate a treeing- formation (hereinafter time to flashover treeing/TTF). In this paper, under a 25 keV primary electron beam energy and for a magnification of 5000·, a 99.95% purity polycrystalline MgO specimen resulted in 7 min TTF. It was also observed that increasing the primary beam energy and the SEM’s magnification decreased the TTF. Therefore, at for a given energy and magnification, this method can be used to evaluate the insulation property of insulators under an electron beam environment. |
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