Time and frequency-resolved surface currents on insulators

The movement of charges deposited from a corona discharge on insulator surfaces was measured using sweeping potential difference V_s applied between electrodes placed on the surface. It is shown that surface charges are relatively highly mobile, provided their density Q_d is sufficiently high, and increase rapidly with Q_d. The collected surface charge Q _s increases rapidly from very low values at low V _s and tends towards Q_d, signifying complete removal. The lateral current i(t) as function of time after the application of V_s is nonexponential, tending to a t^-n dependence, where n<1. The flow of current becomes filamentary at sufficiently high Q_d and V_s