Continuously balanced pulse-DC ioniser to minimise the offset voltage

•A theory for minimising the offset voltage is applied to a pulse-DC ioniser.•Reversing and non-reversing square-wave needles attain continuously balanced ions.•The continuous emission of quasi-neutralised ions can minimise the offset voltage.•Such emission can also transport ions effectively, resulting in faster charge decays.

In our previous work, the AC type of ionisers was employed to demonstrate a prospective theory obtained by numerical simulations in which continuously emitting quasi-neutralised positive and negative ions from corona ionisers can transport ions effectively to a charged object and yield zero offset voltage. In this paper, we show that this can also be applied to pulse-DC ionisers, resulting in significant improvements in the offset voltage as well as charge-decay times. In addition, we present an implementation method with an electronic circuit design to create such an ion emission from a pulse-DC ioniser.

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