Kiel 2004 – scientific programme

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P: Plasmaphysik

P 3: Postersitzung: Niedertemperaturplasmen Plasmatechnologie I, Diagnostische Methoden I

P 3.7: Poster

Monday, March 8, 2004, 17:45–19:30, Foyer

Characterisation and improvement of WEGA performance — •KINGA HORVATH¹, JOHANN LINGERTAT¹, THOMAS BINDEMANN¹, URSEL FANTZ², RALF KÖNIG¹, MICHAEL LAUX¹, YURIJ PODOBA¹, and FRIEDRICH WAGNER¹ — ¹Max-Planck Institut für Plasmaphysik, Euratom Association, TI Greifswald, Wendelsteinstrasse 1, 17491 Greifswald, Germany — ²Institut für Physik, Universität Augsburg, Universitätsstr. 1, 86135 Augsburg, Germany

The WEGA device is a classical stellarator operated in the Greifswald branch of IPP.

A basic diagnostics at WEGA is the Langmuir probe. The Langmuir characteristics show a common property: lack of ion current saturation. This phenomenon can be explained with a model of two-temperature distribution of electron energies. Profiles of plasma parameters were obtained for discharges with different working gas, magnetic field, heating power, neutral pressure and rotational transform.

As separate diagnostics an interferometer and an optical spectrometer are used to measure average T_e and n_e.

The WEGA plasma is heated by ECRH. Different types of antennas have been studied. With the first type, a straight metallic cylinder, hollow T_e and n_e profiles and density values above the cut-off density have been obtained. Trying other type of antennas the n_e profiles became flat or peaked and the T_e profiles slightly hollow. The energy confinement time, the confined energy and the degree of ionisation have been increased under the new heating conditions.