Hannover 2020 – scientific programme

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P: Fachverband Plasmaphysik

P 7: Atmospheric-pressure plasma and applications 2

P 7.6: Talk

Tuesday, March 10, 2020, 12:30–12:45, b305

Ro-vibrational distribution measurements in transient atmospheric pressure plasmas by coherent anti-Stokes Raman scattering — •Jan Kuhfeld, Dirk Luggenhölscher, and Uwe Czarnetzki — Institute for Plasma and Atomic Physics, Ruhr University Bochum, Germany

Ro-vibrational excited molecules govern the plasma wall interaction and the chemical reactions in atmospheric pressure plasmas. Excitation of a molecule can occur by an energetic electron or by collisional transfer from an already excited molecule. One of the key goals in discharge design is optimizing these excitation processes in order to achieve maximum energy efficiency in chemical conversion, e.g. CO₂ into CO. The experimental approach for investigating these processes introduced here is based on a particular coherent anti-Stokes Raman scattering (CARS) scheme. This single shot dual pump CARS scheme provides information on the ro-vibrational population of two molecular species simultaneously, here N₂ and CO₂. Additionally, one of the laser beams for the CARS technique is used to perform electric field measurements via E-FISH (electric field induced second harmonic generation). Excited molecules are created by two separate ns-pulsed APPJ with effluents intercepting. Space and time resolutions are determined by the interaction volume of the lasers and the pulse length respectively. Those are in the order of 100 µm and 10 ns. Here, first measurements of the electric field and the vibrational excitation of Nitrogen in a Helium-Nitrogen mixture are presented.