Production of Monopolar Ions from Streamer Coronas Induced by Very Short Pulse Voltage

The initial and time-dependent concentration of ions in the streamer coronas produced by very short pulse voltages with a half-tail of 100-500 as are measured under the condition that a dc bias voltage is applied between the corona and plate electrodes. The waveform of the corona current of both positive and negative polarities indicates that, although the plasma formation is made in a very short time of about 10 ns, the ionic current flowing across the electrode gap has a very long duration time of 1-3 ms. This is due to the slow processes of ion recombination and migration. The theoretical model of the ion separation process for production of monopolar ionic current is presented and confirmed by the experimental results. The initial ion concentration in these streamer coronas amounts to (5-6) x 109 ion paires/cm3 for both negative and positive streamers.