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P: Fachverband Plasmaphysik

P 16: Poster Session Plasma Physics

P 16.57: Poster

Donnerstag, 19. März 2026, 13:45–15:45, Redoutensaal

Electron densities and temperatures of a microsecond pulsed plasma in water — •Oliver Krettek, Pia-Victoria Pottkämper, Neil Unteregge, Sven Weller, Nils Huber, and Achim von Keudell — Experimental Physics II, Ruhr-Universität Bochum, 44801 Bochum, Germany

Plasma ignition in liquids enables a wide range of applications, including the production of hydrogen peroxide, nanoparticle formation in solution and on surfaces, and plasma-assisted electrolysis, for example in the reactivation of copper catalysts for electrochemical reduction of CO₂. While nanosecond pulsed plasmas typically generate higher yields of reactive species, microsecond pulsed plasmas offer the advantage of easier integration into electrolysis cells. To better understand the behavior of such plasmas prior to their use in an electrochemical system, key plasma characteristics must be determined. In this study, optical emission spectroscopy is applied to investigate the H-alpha and O 777 nm emission lines of a microsecond pulsed plasma in water. By fitting the measured line profiles with a model incorporating Stark, van der Waals, and Doppler broadening, electron densities of up to 10²²   m⁻³ and electron temperatures around 2500 K are obtained for different ignition voltages and pulse frequencies. Additionally, the ignition behavior as a function of electrode distance is examined. Experimental ignition thresholds for varying electrode gaps and voltages are compared with a simulation, showing very good agreement. Remaining discrepancies in the observed slopes may be related to transient bubble formation caused by Joule heating during ignition.

Keywords: Microsecond pulsed plasma; Plasma in liquid