Berlin 2014 – scientific programme

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P: Fachverband Plasmaphysik

P 11: Magnetic Confinement II

P 11.5: Talk

Tuesday, March 18, 2014, 15:50–16:05, SPA HS202

Dynamic behaviour of magnetic flux tubes in the FlareLab experiment — •Felix Mackel, Sascha Ridder, Jan Tenfelde, and Henning Soltwisch — Ruhr-Universität Bochum

Rapidly evolving magnetic flux tubes are generated by a pulsed power plasma experiment. An external magnetic guide field is provided by a strong line current that initially leads to an almost perfect half torus of current-carrying plasma connecting both electrodes. Unbalanced magnetic pressure causes the expansion of the major radius. Measurements with invasive Rogowski coils reveal a saturation of the current that is flowing through the apex of the luminous arch structure soon after ignition. While the appearance of the plasma on ICCD images is rather collimated, the continuously rising discharge current diverges drastically above the footprints. Eventually, the arch loses the visual connection to the electrodes, while the total discharge current still continues to rise. Magnetic pickup coils surrounding the electrodes show that the current paths bulge outward quickly as a consequence of configuration-space instabilities which may be triggered by the preceding widening of the current channel. At the same time, radiation in the extreme ultraviolet spectrum is detected by a photodiode covered with a thin metal foil acting as a bandpass filter. A physical model is proposed to account for the generation of fast particles that possibly provoke the emission of EUV light.