Secondary ionization mechanisms in the electrical breakdown of neon

The formative time lags for nickel electrodes in neon have been measured over the reduced-pressure range 20-60 torr (reduced to 0°C) and the E/N range (field per unit concentration) from 4·3 × 10 -16 to 7·5 × 10 -16 v cm 2 . A temporal growth theory by Davidson, with adjustable parameters, was used to calculate theoretical formative time lags to fit the experimental results, providing values of the secondary ionization coefficients. At low values of E/N the predominant secondary ionization process was electron emission from the cathode by delayed photons released from metastable states by collisions with gas molecules. As E/N was increased, electron emission by positive ions and undelayed photons became more important.