Transient spark in N2-CO2 mixture above water surface at atmospheric pressure
Janda M., Machala Z., Hensel K., Morvová M.
Acta Phys.. Univ. Comenian. LIII, 15-25 (2016)
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Abstract: The paper demonstrates several ways of use of the UV-VIS optical emission spectroscopy of medium resolution for the diagnostics of atmospheric pressure air and nitrogen plasmas relevant to bio-medical and environmental applications. Plasmas generated by DC discharges (streamer corona, transient spark, and glow discharge), AC microdischarges in porous ceramics, as well as microwave plasma were investigated. Molecular (OH, NO, CN) and atomic (H, O, N) radicals and other active species (e.g. N2 (C, B, A), N2+ (B)) were identified. The composition of emission spectra gives insight in the ongoing plasma chemistry. Rotational, i.e. gas, and vibrational temperatures were evaluated by fitting experimental with simulated spectra. Streamer corona, transient spark and microdischarges generate cold, strongly nonequilibrium plasmas (300-550 K), glow discharge plasma is hotter, yet nonequilibrium (1900 K), and microwave plasma is very hot and thermal (~3000-4000 K). Electronic excitation temperature and OH radical concentration were estimated in the glow discharge assuming the Boltzmann distribution (9800 K, 3e16 cm-3). Optical emission also provided the measurement of active plasma size of the glow discharge, and enabled calculating the electron number density (10e12 cm-3).
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