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Effect of negative ions on electrical breakdown in a nonuniform air gap between a wire and a plane

Electrical breakdown of an axisymmetric, atmospheric pressure air gap between a wire and a plane has been investigated for a gap length of 0.5 mm. O− and O−2 have been identified as the negative ions affecting the discharge development in air, besides electrons and positive ions, and have been included in the electrical breakdown model. Five coupled two‐dimensional transient partial differential equations describing the discharge evolution in the air gap have been solved using a finite difference algorithm developed earlier. Temporal development of the charged particle number densities, electrostatic potential, electric field, and current at both the electrodes is presented when the wire is negatively biased at 2500 V. The impact of negative ions on gap breakdown has been assessed by comparing the results of analyses with and without negative ions. It is concluded that the negative ions have negligible effect during the early stages of the discharge development. However, as the discharge evolves, the nega...