  Measurements of force generated by a positive unipolar wire-to-plane corona
discharge in air are compared with numerical simulations. The generated force
does not depend on the ion or electron 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.
