Study on pre-fire phenomenon for multiplex high-energy spark gap switches with graphite electrodes

In a high-power laser facility with multiplex power modules, the dispersion of self-breakdown voltages of spark gap switches might result in a so-called pre-fire problem. Pre-fire probability of spark gap switches with graphite electrodes must be constrained at extremely low level. In this paper, Pe...

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Bibliographic Details
Published in:IEEE transactions on dielectrics and electrical insulation 2012-06, Vol.19 (3), p.886-892
Main Authors: Li, Lee, Xiangdong, Qi, Li, Cai, Fuchang, Lin
Format: Article
Language:English
Subjects:
Constants
Discharges
Dispersions
Electrodes
Equations
Graphite
graphite electrode
Mathematical model
Mathematical models
Multiplexing
Probability distribution
self-breakdown
Spark gap switches
Spark gaps
Sparks
Studies
Surface discharges
Switches
Weibull distribution
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Summary:In a high-power laser facility with multiplex power modules, the dispersion of self-breakdown voltages of spark gap switches might result in a so-called pre-fire problem. Pre-fire probability of spark gap switches with graphite electrodes must be constrained at extremely low level. In this paper, Pedersen model was used to explain the causes of pre-fire. The microscopic surface roughness of worn graphite electrodes had a major impact on pre-fire. And this paper had deduced the cumulative probability distribution of pre-fire, and given a relevant Weibull distribution equation. Several typical graphite materials were tested too. The experimental results revealed that electrodes should use graphite with higher hardness, smaller particle size and greater flexural strength. This was consistent with the analysis of Pedersen model. More significantly, based on the experiments of typical graphite materials, two Weibull constants of the cumulative probability distribution of pre-fire were obtained by a graphing method. Therefore, it is possible to calculate, reduce or control the occurrence of pre-fire in a facility with many gas switches. Via optimizing the operating under-voltage ratio of multiplex switches, the expectable pre-fire probability can be achieved.
ISSN:1070-9878
1558-4135
DOI:10.1109/TDEI.2012.6215091