SMuK 2023 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 11: Poster I

P 11.1: Poster

Mittwoch, 22. März 2023, 14:00–15:30, HSZ EG

Novel microwave interferometry approach for spatial plasma profile measurements — •Christos Vagkidis, Eberhard Holzhauer, Walter Kasparek, Alf Köhn-Seemann, Stefan Merli, Mirko Ramisch, and Andreas Schulz — IGVP, University of Stuttgart, Germany

Interferometry is widely used in plasma physics to obtain the line-integrated density of a plasma. Here, we present a method to obtain in addition information about the spatial profile of the plasma density from interferometry measurements with the help of accompanying full-wave simulations. For this purpose, a microwave-generated plasma torch is used, which is confined in a quartz tube. A high frequency (208 GHz) microwave beam is emitted by a horn antenna, perpendicular to the plasma, and used as a probing beam. The receiving antenna is placed behind the plasma and is aligned with the sending antenna. The reference beam is generated artificially from a network analyser, which measures the phase difference of the beams. In spite of the beam being scattered, the phase difference can still be used to calculate the line-integrated density of the plasma with reasonable accuracy. Furthermore, the intensity distribution of the probing beam, in the plane perpendicular to the plasma torch, is obtained by moving the receiving antenna with a stepping motor, which can be operated with sub-millimetre precision. Full-wave simulations (inhouse FDTD code and COMSOL Multiphysics) have been carried out with arbitrary plasma density profiles. Comparing the simulation results with experiments allows to deduce information on the actual density profile.