Electrical discharges from and between clouds of charged aerosols

Charged aerosol clouds emerging from supersonic nozzles have been used to induce electrical breakdown from large falling drops of water. As expected, it is shown that only positive streamers are produced independently of the polarity of the aerosol. These streamers are not suppressed by spray from the drop, and their propagation is enhanced through negative aerosols. Two interacting jets have been used to produce very high concentrations of aerosol space charge in a region far removed from any electrodes. For positive charge this region behaves like a positive corona discharge. For negative charge the local negative streamer breakdown produced invokes either positive streamers or actual sparks from nearby regions depending on the charge density of the aerosol. The physical mechanism required for the explanation of the results obtained completely agrees with, and supports, Loeb's recent theory for the formation of stepped leaders in lightning discharges. It is shown that breakdown between positive and negative aerosols can also be obtained by means of interacting jets.