title: Nature of charge carriers in negative coronas.
abstract: Mass spectrometric studies of ionic species formed in negative corona discharges in air and pure oxygen have been carried out at total pressures ranging from 5 Torr to 760 Torr. In air, the importance of trace amount of carbon dioxide is demonstrated by the dominant presence CO(3)(-) ion at pressures above 50 Torr. This ion comprises over 90% of the total ionic species which reach the anode at atmospheric pressure. At relative humidities of 20-50%, the contributions of the hydrated species such as CO(3)(-)(H(2)O), O(-)(H(2)O), and O(3)(-)(H(2)O)) are less than 10%. In pure oxygen the two important ionic species appear to be O(3)(-) and O(-) with the contribution of the former increasing with pressure. Trace impurities of carbon dioxide in oxygen, however, convert the carriers to CO(3)(-) which makes the dominant contribution to the total current.
authors.forename: M M
authors.initials: MM
authors.lastname: Shahin