Electrostatic force measurements in positive unipolar wire-to-plane corona discharges in air

Measurements of electrostatic force generated in the drift region of a positive unipolar wire-to-plane corona discharge in air are compared with numerical simulations. The generated force does not depend on the ion mobilities, preventing the influence of uncertainty and variation of these parameters. A method is described to simulate the voltage and charge distribution for a wire-to-plane set-up. This method enables the determination of the transition between unipolar and bipolar discharges. In the experimental set-up breakdown electric field of air reduces with increasing discharge current.