Abstract
In this paper, streamer discharge in dielectric liquids which have various molecular structure, such as a double bond or a triple bond in molecular formula, is observed in detail for positive point polarity, under the application of an impulse voltage to the point electrode. As test liquids, four kinds of straight - chain hydrocarbon liquids such as n-hexane, n-heptane, n-octane and n-decane are selected and also the influence of a double bond or a triple bond included in their molecular formula on the propagation of positive streamers in these hydrocarbon liquids is investigated in detail by using a high-speed schlieren method and a current measurement system by LED, simultaneously. As a result, there are some differences in the mean propagation velocity and the propagation shape of positive streamers are seen obviously. Their shape is mainly filamentary in test liquids including a double bond or a triple bond. Also, in their liquids, positive streamer propagation are promoted. It is thought that this is due to the effect of π bond which has smaller bond energy than σ bond.
