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P: Plasmaphysik

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

P 12.17: Poster

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

Measurement of electron density and temperature of a low–temperature ECR discharge by Li atom beam diagnostics — •Chr. Krause¹, D. Hemmers¹, H. Kempkens¹, S. Meier¹, H. B. Schweer² und J. Uhlenbusch¹ — ¹Institut für Laser– und Plasmaphysik, Universität Düsseldorf — ²Institut für Plasmaphysik, FZ Jülich

Measurements of the ratio of line intensities emitted by a lithium atom beam is a well known technique to determine the electron density in the edge of high–temperature plasmas, e.g. Tokamak discharges. First measurements in a low–temperature ECR plasma show that it is possible to determine also the electron temperature provided the electron density is already known, e.g. by Thomson scattering. For this purpose the ratio of the line intensity of the Li–transition 3d–2p at 610 nm to the intensity of the transition 2p–2s at 670 nm is used. In particular at high input power the comparison with the T_e data obtained by Thomson scattering show deviations. For this reason the collisional–radiative model employed to calculate the population densities of the Li–levels has been improved by increasing the number of considered main quantum levels from four to twelve. By the additional measurement of the third Li transition 3s–2p at 812 nm and simultaneous evaluation of two intensity ratios both the electron density and temperature could be determined without data of any other diagnostics. This work is supported by the DFG within the scope of the SFB 191.