Interaction of the `Trichel' current pulses of a pair of negative coronas

The interaction of Trichel current pulses of neighbouring negative needle coronas is investigated. As the needles are brought together and the strength of the coulomb interaction increases, the experiments show that (i) the pulse frequencies decrease, (ii) the frequencies converge, and (iii) the relative phase of the pulses approaches π. A coupled circuit model of the interaction between the charge clouds is presented which shows that these observations are dictated by energy considerations. Localized Trichel corona spots also occur on negative corona wires, and the behaviour of these discrete discharge spots is explained by experiments and analysis.