Problems in design of ignition test cells for use with pulsed radar sources

The results of a detailed study of breakdown phenomena and flammable gas ignition in a fixed-gap ignition cell fed by a pulsed radar source are presented. It is reasoned that the large electrode gap widths that are necessary with hydrocarbon fuels lead to a situation where any spark that occurs is certain to cause ignition, and the probability of ignition is determined by the probability of occurrence of a spark. This is, in turn, largely determined by statistical time lag, which approaches infinity as the input power is reduced. It is concluded that a `breakflash´ type of ignition cell may give more consistent results than a fixed-gap design, although the rate of occurrence of breaksparks in current designs is excessively low