SMuK 2021 – scientific programme
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P: Fachverband Plasmaphysik
P 1: Low Pressure Plasma Sources I
P 1.2: Talk
Monday, August 30, 2021, 11:30–11:45, H5
Spectroscopic determination of rotational and vibrational temperatures in nitrogen microwave discharges from low to atmospheric pressure — •David Rauner1, Alistair Brydon2, Ante Hecimovic2, and Ursel Fantz1,2 — 1AG Experimentelle Plasmaphysik, Universität Augsburg, 86135 Augsburg — 2Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching
Microwave (MW) discharges allow to cover a large pressure range: from the low-pressure, non-equilibrium regime of several Pa up to atmospheric conditions where heavy particle collisions play a dominant role and (partial) thermal equilibrium can typically be observed.
To demonstrate the transition between these low- and high-pressure regimes in MW plasmas, nitrogen discharges are excellently suited: via high-resolution optical emission spectroscopy and molecular spectra simulation, rotational and vibrational temperatures of different excited molecular species (N2(B, C), N2 +(B)) can be assessed. To cover the required large pressure range experimentally, two laboratory microwave plasmas driven at 2.45 GHz are utilized: a surface wave discharge (surfaguide) for the pressure range between 3 Pa and 2000 Pa and a microwave plasma torch, capable to operate at higher pressures up to atmospheric conditions. By assessing almost six orders of magnitude in pressure, a gradual equilibration of rotational and vibrational distributions is clearly seen and discussed in this contribution.