Section Days abstract book 2010.indd - RUB Research School ...

NSE_12
LASER ELECTRIC FIELD MEASUREMENTS
IN MICRODISCHARGES
Sarah Müller, Dirk Luggenhölscher and Uwe Czarnetzki
Institute for Plasma and Atomic Physics
Ruhr-Universität Bochum, 44780 Bochum, Germany
email: sarah.mueller@rub.de
Electric field induced coherent Raman scattering (E-CRS) measurement is a promising
technique for measuring electric fields in high-pressure environments and was first
demonstrated with hydrogen molecules by Ochkin and Tskhai in 1995. The technique is ideal
for the investigations of microdischarges at atmospheric pressures. The frequencies of two
focussed laser beams in the visible are tuned to match the energy difference between the two
lowest virational levels in hydrogen. The presence of a static electric field then leads to the
emission of coherent IR radiation at this difference frequency. The signal intensity scales with
the square of the static electric field strength. In parallel to this process also anti-Stokes
radiation in the UV by the standard CARS process is generated. Normalization of the IR
signal by the UV signal provides a population independent measurement quantity.
No further knowledge of other gas/plasma parameters such as the gas density is required for
the measurement.
Further details on the measurement technique as well as measurement results in
microdischarges will be presented.