Jena 2013 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 10: Poster: Plasmadiagnostik

P 10.13: Poster

Mittwoch, 27. Februar 2013, 16:30–18:30, Poster EG

Calibration of the magnetic diagnostics for the Wendelstein 7-X-stellarator — •Thomas Windisch, Michael Endler, Olaf Grulke, and Thomas Sunn Pedersen — MPI for Plasma Physics. EURATOM association, 17491 Greifswald

The W7-X stellarator will be equipped with a multitude of magnetic diagnostics. In order to reconstruct the magnetic equilibrium the plasma energy, plasma current, Pfirsch-Schlüter currents and the plasma current distribution have to be measured with high accuracy. The diagnostics for this purpose consist of diamagnetic loops, saddle loops and Rogowski coils. Due to the long pulse length up to 1800 s the signal amplitude exhibits a variation up to nine orders of magnitude. In addition magnetic fluctuations, e.g. due to Alfvén eigenmodes, are measured using 120 Mirnov coils in the high frequency range f<1 MHz. In this presentation the planned calibration system of the assembled equilibrium diagnostics is discussed. Since eddy currents in the plasma vessel and wall protection elements strongly affect the signals, the calibration can not be done prior to assembly. Additionally, the influence of perturbing signals like the current flowing in the W7-X field coils has to be analyzed.The calibration system is based on four toroidal wires that are driven with frequencies up to 2 kHz and currents up to 2 kA. The use of several toroidal wires allows testing of the segmented Rogowski coils. These coils will be used to measure the current distribution in the plasma. The calibration system will be used to quantify the degree of pickup signals in the diamagnetic loops, which in principle should be immune to toroidal currents.