Berlin 2014 – scientific programme

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P: Fachverband Plasmaphysik

P 13: Poster Session - Diagnostics

P 13.16: Poster

Tuesday, March 18, 2014, 16:30–18:30, SPA Foyer

Detection limit of the interferometric hook method for absolute species density measurements at atmospheric pressure plasmas — •Torsten Gerling, Mathias Andrasch, René Bussiahn, Christian Wilke, and Klaus-Dieter Weltmann — INP Greifswald

Measurements of absolute densities in atmospheric pressure plasmas still prove to be challenging. Therefore, the hook method is applied to test the chances of measuring these absolute values. When a background light source passes the plasma in the spectral region of a transition, anomalous dispersion appears. The width of the anomalous dispersion depends on the density of the lower state of the transition, the oscillator strength and the length of absorption. In order to measure the anomalous dispersion, the light passes an interferometer and is afterwards spectrally resolved by a grating and detected by a CCD camera. Within our investigations, we focussed on the OH radical in a flame, in a microwave plasma source and a MHz plasma source. We will therefore discuss the detection limit of the hook method and assess the limit for other species like atomic oxygen O.