Precisely balanced ionizer using atmospheric pressure glow discharge in air

Ion balance of an ionizer previously developed has been improved, using an atmospheric pressure glow discharge in air as a bipolar ion source. Although the glow ionizer itself has had good performance in ion balance, further we have investigated the possibility of precise control of the ion balance by controlling the discharge itself or the ion flow from the discharge to the object to be neutralized. To control the discharge, we have adjusted the voltage waveform to produce the glow discharge: a dc bias voltage superimposed on a sinusoidal waveform or widths of positive and negative rectangular pulses. Also an adjustable potential of a grid electrode additionally arranged has been employed to control the ion flow. By controlling any of them, we have succeeded in precisely controlling the ion balance of the glow ionizer.