Grundlegende Untersuchungen zur Plasmachemie an mit Luft-Wasserdampf-Mischungen betriebenen dielektrisch behinderten Entladungen unterhalb Atmosphärendruck
Zusammenfassung der Projektergebnisse
The project dealt with the investigation of the fundamental plasma-chemical reaction mechanisms leading to the controlled generation of reactive oxygen and nitrogen species (RONS) in dielectric barrier discharges (DBDs) operating with mixtures of argon, air, and water vapour. A novel type of sub-atmospheric-pressure, low-temperature dielectric barrier discharge was employed, which is termed Venturi-Vapour DBD (VV-DBD). It uses a Venturi pump to transfer the plasma-generated RONS from the plasma zone to atmospheric pressure. Two main device versions of the VV-DBD plasma source were established during the project. The VV-DBD in-situ device was used for the analysis of the electrical characteristics as well as for absorption and emission spectroscopic investigations of discharges in rare gases. The VV-DBD planar device was employed as technological basis for investigations using dry air and mixtures of air and water vapour. The analysis comprised Fourier-transform infrared (FTIR) spectroscopy measurements of several RONS species in the downstream region outside the plasma source in combination with time-dependent global modelling involving extended plasma-chemical schemes for dry and humidified air. Using the VV-DBD in-situ device operated with argon, results of time-dependent, spatially one-dimensional modelling studies were validated by measurements of the discharge current, of the absolute number density of the metastable Ar[1s5 ] atoms, and of the phase-resolved optical emission of Ar[2p1 ] atoms for a larger range of pressure, voltage amplitude, and frequency. Using the VV-DBD planar device operated with dry air and air with a relative humidity of up to 84 %, the number densities of O3 , NO, NO2 , N2 O, H2 O2 , HNO2 , and HNO3 in the downstream region outside the VV-DBD obtained by FTIR measurements and model calculations showed generally fair agreement for the parameter range of pressure and power considered. The analysis showed that the gas temperature and the relative humidity have a remarkable influence on the composition of the RONS. They can be used to tune the operation from an O3 to an NOx dominated mode, where an increasing number density of H2 O2 , HNO2 , and HNO3 is found for growing relative humidity. The analysis showed as well that a larger residence time of the plasma in the discharge region is favourable for larger number densities of the desired RONS outside the plasma source. These findings are directly relevant for the optimisation of the VV-DBD concept as a tool to improve the efficacy and efficiency of practical applications in plasma medicine and for decontamination. Selected results were published in four articles in peer-reviewed journals so far.
Projektbezogene Publikationen (Auswahl)
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Monitoring of a dielectric barrier discharge-based process using the gas gap voltage. Plasma Sources Science and Technology, 28(2), 025002.
Bansemer, Robert; Schmidt-Bleker, Ansgar; van Rienen, Ursula & Weltmann, Klaus-Dieter
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Influence of surface parameters on dielectric-barrier discharges in argon at subatmospheric pressure. Plasma Sources Science and Technology, 29(12), 125009.
Stankov, M.; Becker, M. M.; Bansemer, R.; Weltmann, K.-D. & Loffhagen, D.
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On the Ar(1s 5 ) density distribution in a flow-driven DBD at intermediate pressure. Plasma Sources Science and Technology, 29(3), 035026.
Bansemer, Robert; Winter, Jörn; Schmidt-Bleker, Ansgar & Weltmann, Klaus-Dieter
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Spectroscopic investigation of a neon-operated DBD at atmospheric and intermediate pressure. Plasma Research Express, 2(3), 035011.
Bansemer, Robert; Scholten, Laura Vilardell; Winter, Jörn & Weltmann, Klaus-Dieter
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“Computer assisted development and optimization of a variable dielectric barrier discharge”, PhD thesis, University of Rostock
R. Bansemer
