Transient spark in air at atmospheric pressure

We have investigated a novel type of streamer-to-spark transition discharge in air at atmospheric pressure, named the transient spark (TS). Despite the DC applied voltage, TS has a pulsed character with very short (<100 ns) high current (>1 A) pulses, with repetitive frequencies of a few kHz. The emission of N
₂
2
^nd
and 1
^st
positive, N
₂

⁺
1
^st
negative, and of the atomic N and O lines, was detected. The non-equilibrium character of TS was confirmed by calculated vibrational (3000-5000 K) and rotational (500-1500 K) temperatures. Additionally, temporal emission profiles were obtained using PMT measurements.