A comment on the methods of calculation of corona onset voltage

Abstract
Two methods of calculating corona onset voltage (cov) in nonuniform air gaps are studied. The variation of number of electrons (or positive ions) in primary and secondary electron avalanches for short (⩽20 cm) as well as long (2–10 m) positive point‐to‐plane air gaps is obtained. Several conclusions regarding critical charge carrier numbers are drawn from this study.