The understanding of the ro-vibrational dynamics in molecular (near)-atmospheric pressure plasmas is essential to investigate the influence of vibrational excited molecules on the discharge properties. In a companion paper Kuhfeld et al (2021 J. Phys. D: Appl. Phys. 54 305204), results of ro-vibrational coherent anti-Stokes Raman scattering (CARS) measurements for a nanosecond pulsed plasma jet consisting of two conducting molybdenum electrodes with a gap of 1 mm in nitrogen at 200 mbar are presented. Here, those results are discussed and compared to theoretical predictions based on rate coefficients for the relevant processes found in the literature. It is found, that during the discharge the measured vibrational excitation agrees well with predictions obtained from the rates for resonant electron collisions calculated by Laporta et al (2014 Plasma Sources Sci. Technol. 23 065002). The predictions are based on the electric field during the discharge, measured by electric field induced second harmonic generation Kuhfeld et al (2021 J. Phys. D: Appl. Phys. 54 305204), Lepikhin et al (2020 J. Phys. D: Appl. Phys. 54 055201) and the electron density, which is deduced from the field and mobility data calculated with Bolsig+ Hagelaar and Pitchford (2005 Plasma Sources Sci. Technol. 14 722–33). In the afterglow a simple kinetic simulation for the vibrational subsystem of nitrogen is performed and it is found, that the populations of vibrational excited states develop according to vibrational-vibrational transfer on timescales of a few microseconds, while the development on timescales of some hundred microseconds is determined by the losses at the walls. No significant influence of electronically excited states on the populations of the vibrational states visible in the CARS measurements (v < 7) was observed.
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|Plasma Source Specification|
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The applied voltage by the DC high voltage generator is 3 or 4 kV with a voltage pulse length of 200-250 ns and a repetition rate of 1 kHz.
English (United States)
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pure nitrogen, flow rate: 20 sccm, pressure: 200mbar
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Data and Resources
- Fig. 6, electron densitycsv
Bulk electron density deduced from the electric field (EFISH) and the...
- Fig. 8/A1/A2csv
Simulation data in figures 8, A1 and A2.
- Fig. 7, Rhcsv
Model data in fig. 7.
- Fig. 3, excitation temperature, theorycsv
Data of the surface plot in fig. 3. Temperature of the newly excited...
- Fig.4, vib. excitation rate, theorycsv
Data of the surface plot in fig. 4. Effective excitation rate (for...