Verification of positive streamer mechanism for negative corona Trichel pulses in O2/H2 mixtures

• The first negative corona pulses in O2 + H2 at sub atmospheric pressures were studied.
• The results confirm the positive-streamer mechanism for Trichel pulse formation.
• The role of secondary photoemission processes from cathode was confirmed.
• The hydrogen in oxygen causes the decrease of attachment coefficient.

Current waveforms of the first negative corona pulses have been measured in O2 + H2 mixtures at a pressure range from 27 kPa to 50 kPa. It was observed that the hydrogen admixtures less than 4% do not change significantly the pulse current waveforms. Effects of changing cathode secondary electron emission were studied using a copper cathode coated by CuI and graphite. The results obtained support the theory of the cathode-directed streamer formation during the negative corona pulse rise.