Initial Phases of Negative Point-to-Plane Breakdown in N₂ and N₂+10%CH₄: Verification of Morrow's Theory

Measurements have been made of initial phases of breakdown in a short negative point-to-plane gap in nitrogen and in a N 2 +10%CH 4 mixture at pressures of 25∼100 Torr in order to verify Morrow's theory of stepped pulses in negative corona discharges. This theory explains the step observed on the current growth (Trichel pulse) wavefront in terms of independent photon and ion secondary processes at the cathode. The comparison of current growth waveforms in N 2 and in a N 2 +10%CH 4 mixture, where photoemission is suppressed, shows good qualitative agreement with Morrow's theory.