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P: Fachverband Plasmaphysik
P 5: Plasma Diagnostics
P 5.6: Poster
Montag, 13. März 2017, 16:30–18:30, HS Foyer
A new laser blow off system on the W7-X stellarator. — •Th. Wegner1, B. Geiger1, R. Burhenn1, S. Knauer2, R. Foest3, and V. Winters4 — 1Max-Planck-Institute for Plasma Physics, Greifswald, Germany — 2Institute of Physics, Greifswald, Germany — 3Leibniz Institut for Plasma Science and Technology , Greifswald, Germany — 4University of Wisconsin, Madison, Wisconsin, USA
The impurity confinement in stellarators can lead to impurity accumulation and early pulse termination by radiation collapse. In particular, the impurities in the plasma influence the power balance by increasing the radiation losses and the dilution of the plasma. The investigation of the impurity transport is a demanding task for steady-state operation. Hence a new laser blow off (LBO) system on the W7-X will be used to insert impurities to the plasma edge in a controlled manner. Therefore, a Nd:YAG laser beam is guided through an optical system to the coated glass target which is positioned inside the torus. By using a movable lens and mirror, the position of the laser spot on the glass target as well as its diameter can be varied. Hence, single atoms, clusters, ions as well as electrons can be ablated depending on the coating, the thickness and the laser energy density on the glass target. In OP 1.2, the glass targets will be positioned by means of a multi-purpose manipulator. The transport of the impurity can be studied using different diagnostics, e.g., emission spectroscopy. This contribution reports on the design status of the LBO system and the quantitative tests regarding the ablation of the coatings which will be used in OP 1.2.