Corona discharge from a grounded needle electrode inserted into a charged droplet cloud

Abstract

The discharge occurring in a space-charge cloud was investigated by using a cloud of charged droplets. To produce a charged cloud with a definite space charge density and to cause a reproducible discharge, droplets ejected from an airless nozzle were induction charged and transported by air flow. The transportation of charged droplets by air flow was found to be quite effective in increasing the charge on the droplets and the charge density. Corona discharge was observed at a grounded needle electrode inserted into a charged droplet cloud with a charge density not exceeding 13 μC/m3. In negatively charged droplets, positive streamer coronas occurred. As the charge density of the cloud increased, the time interval of streamer pulses decreased and the discharge shifted to a glow corona. In positively charged droplets, the height and frequency of negative corona pulses increased with the charge density and the velocity of the charged droplet cloud. © 1998 Scripta Technica. Electr Eng Jpn, 122(4): 1–7, 1998