The mobility coefficients provide the mean value of mobility for the ion swarm of a certain species and not of individual ions. The distance traversed by an ion swarm in an electric field can be estimated by using the ion’s mobility value and the expected electric field magnitude. At 30 kHz, the time available for charge carriers to cross the air gap is 16.6 μs (the duration of the half-cycle at that frequency). The strongest electric field calculated (breakdown voltage divided by gap length) in the present experiments was 22.5 kVrms/cm. This was obtained for a 4 mm gap. Using this field strength, the mean distance traversed by O3-, O2- and O- ions can be estimated as 9.5, 8 and 12 mm in a half cycle of 30 kHz, respectively. These distances are comparable to the gap lengths evaluated in this project.