Erlangen 2018 – scientific programme

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P: Fachverband Plasmaphysik

P 6: Codes and Modelling

P 6.1: Invited Talk

Monday, March 5, 2018, 16:15–16:45, KI 1.174

Collisionless damping in the spectra of active plasma resonance spectroscopic probes — •Jens Oberrath — Institute of Product and Process Innovation, Leuphana University Lüneburg, Germany

Different designs of probes, which are based on the concept of active plasma resonance spectroscopy, were invented since the early sixties of last century. Within the last decade improved designs gained new interest as possible devices for industrial plasma diagnostics. Therefore, a mathematical model to determine simple relations between plasma and resonance parameters is needed. A suitable choice to derive a simple model is based on a fluid description of the plasma. However, in low pressure plasmas a fluid model can only predict the resonance frequency, which is related to the electron density. To measure also the electron temperature simultaneously in one measurement, a relation to a second resonance parameter is needed. Such a parameter is given by the half width of the peak, which is related to the damping of the system. In low pressure plasmas not only collisional damping takes place, but also collisionless, which has to be determined kinetically. Within this work, spectra of different probe designs are compared, some are determined by a fluid and others by a kinetic model. It will be shown, that a broadening of the resonance is caused by kinetic effects. Furthermore, good agreement of the spectra can be reached, if the collisionless damping is added to the collisional damping in the fluid calculations.
The author acknowledges the financial support by internal funding of Leuphana University and the German Research Foundation (DFG) via the project OB 469/1-1.