Bochum 2015 – scientific programme

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P: Fachverband Plasmaphysik

P 9: Diagnostics I

P 9.6: Talk

Tuesday, March 3, 2015, 12:20–12:35, HZO 30

Laser-spectroscopic electric field measurements in near atmospheric ns-pulsed microplasmas in hydrogen and nitrogen — •Patrick Böhm¹, Ben Goldberg², Igor Adamovich², Walter Lempert², Dirk Luggenhölscher¹, and Uwe Czarnetzki¹ — ¹Institute for Plasma and Atomic Physics, Ruhr-Universität Bochum, Bochum, Germany — ²Department of Mechanical and Aerospace Engineering, the Ohio State Universiy, Columbus, Ohio, USA

This work focuses on laser-spectroscopic electric field measurements in a fast ionization wave amongst other near atmospheric pressure ns-pulsed discharges in hydrogen and nitrogen. The laser technique for the electric field measurements is based on a four-wave mixing process similar to CARS (Coherent anti-Stokes Raman Scattering). This technique works in diatomic gases like hydrogen or nitrogen at higher pressures. The electric field can be calculated from the ratio of the generated signals without the necessity of knowing e.g. the gas density or any further parameters. A calibration measurement has to be applied to achieve absolute values for the electric field. Depending on the pulse width of the utilized laser system a high temporal resolution up to approximately 150 ps can be achieved. A sensitivity of around 50 - 100 V/mm in a pressure-range of 0.3 * 1 bar in pure nitrogen is achieved. The performance of Hydrogen is even better with sensitivities of up to 3 V/mm in 1 bar of pure Hydrogen. This made temporally and spatially resolved electric field measurements in a fast ionization wave in pure hydrogen possible. It also enables the use of Hydrogen as a tracer gas in non-Hydrogen discharges.