Transient spark in air at atmospheric pressure
Janda M., Machala Z., Stancu G.D., Pai D., Lacoste D., Laux C.O.
XVII International Conference on Gas Discharges and their Applications, Cardiff, UK, September 7-12, p. 349-352 (2008)
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Abstrakt: We investigated a novel type of streamer-to-spark transition
discharge in air and N2/CO2/H2O mixtures at atmospheric pressure,
named transient spark. Despite DC applied voltage it has a pulsed
character with very short (~100 ns) high current (~1 A) pulses with
repetitive frequencies of some kHz. Thanks to the very short spark
pulse duration given by the small internal capacity of the discharge
system and the limiting series resistor, the plasma cannot reach LTE
conditions. The electrical and optical properties of transient spark
were studied as functions of the frequency and the gas composition
by oscilloscopic measurements, ICCD camera imaging and optical
emission spectroscopy with high temporal and spectral resolution.
Depending on the gas used, the emission of N2 2nd and 1st positive,
N2+ 1st negative, CN violet and red, OH (A-X) and NH (A-X) systems,
as well as atomic N, O, H, and C lines were detected.
Its non-equilibrium character was confirmed by calculated
vibrational (3000-4000 K) and rotational (500-1000 K) temperatures.
Transient spark provides a potential and was examined for various
applications, such as bio-decontamination or flue-gas cleaning (in air),
or CO2 decomposition followed by the synthesis of organic species
(in N2/CO2/H2O mixtures).
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