Studies of electrostatic surface discharges on corona-charged polymer surfaces

Electrostatic surface discharge phenomena on corona-charged thin polymer films such as FEP or PTFE teflon, whose surface potentials were from 1 to 5 kV in both polarities, were studied. A grounded sphere electrode 5 mm in diameter was moved toward the charged surface by a computer-controlled step motor until the surface discharge occurred. Discharge-current waveforms with risetimes of a few nanoseconds were observed and were related to the lengths (5-30 cm) or type (single wire or plain mesh) of ground line used. The length gap between the film surface and the grounded electrode at discharge were calculated and shown to be strongly dependent on the polarity of the surface charge. The values diverged widely, indicating a complicated surface-discharge mechanism.<>