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P: Fachverband Plasmaphysik

P 2: Magnetic Confinement I

P 2.6: Vortrag

Montag, 2. März 2015, 12:10–12:25, HZO 30

Experimental investigation of a rapidly moving arch-shaped plasma — •Sascha Ridder, Felix Mackel, Jan Tenfelde, and Henning Soltwisch — Ruhr-Universität Bochum

In the FlareLab experiment, rapidly evolving magnetic flux tubes are generated by igniting a pulsed-power discharge along an external circular magnetic field, producing an initially arch-shaped plasma, which expands into the vessel on a microsecond time scale. The plasma has its footpoints on the electrode surfaces where instability phenomena appear in the course of the discharge evolution. Eventually, the plasma arch loses its visible connection to the electrode surface, while the discharge current continues to rise. Interferometric and Rogowski coil measurements in different locations along the plasma arch revealed a different arch morphology than initially suspected based on CCD camera images. Interferometric data obtained in the footpoint region of the arch show high density gradients either in radial or in axial direction and link the dark regions above the electrodes to electron density depletion after the arch has lost its connection to the footpoints. Those measurements are accompanied by CCD camera images which in comparison with numerical simulations indicate a kink instability in the footpoint region of the plasma arch.