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P: Plasmaphysik

P 12: Plasma Wall Interaction, Diagnostic and Low Temperature Discharges (Poster Session)

P 12.18: Poster

Freitag, 6. April 2001, 12:30–15:00, AT2

Recent Progress in the Lithium-Beam Diagnostic for Tokamak Edge Plasmas — •Thomas Naiser, Hans-Werner Müller, and Elisabeth Wolfrum — Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, D-85748 Garching

The neutral Lithium beam is an established diagnostic tool for the measurement of edge electron densities at ASDEX Upgrade [1,2]. To increase its penetration depth into the plasma and thus its useful range, an upgrade from 35 kV to up to 100 kV acceleration voltage is currently implemented. Not only the increased acceleration voltage but also an optimised emitter geometry lead to higher current densities, required for the measurement of ion temperatures with Lithium-beam charge exchange spectroscopy.

Moreover, an alternative evaluation procedure [3] involving neural networks is investigated with regard to its reliability and speed. As the plasma edge density seems to influence the central plasma density, a fast edge density diagnostic could be integrated in online plasma control. We report on recent progress and the current status of this diagnostic.

[1] McCormick et al, Fusion Eng. Design 34-35, 125 (1996)

[2] Schweinzer et al, Plasma Phys. Control. Fusion 34, 1173 (1992)

[3] Dragosics, Diplomarbeit, TU Wien (2000)