D.C. corona on smooth conductors in air. Steady-state analysis of the ionisation layer

A theoretical analysis of the electric-field distribution in the ionisation layer of a d.c. corona discharge under equivalent steady-state conditions is presented for both positive and negative polarities of the conductor. Using available experimental data on ionisation and attachment coefficients in air, the condition for corona onset is analysed on the basis of the Townsend theory. Subsequently, the field distribution in the corona layer is determined for different values of total equivalent steady-state corona current.