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Spectroscopy – A Powerful Diagnostic Tool in Source Development
U. Fantz, H. Falter, P. Franzen, S. Christ, B. Heinemann, A. Lorenz, W. Kraus, P. McNeely,
R. Riedl, E. Speth, D. Wünderlich
Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748
Garching, Germany
Abstract : Development of negative hydrogen ion sources for neutral beam systems is closely linked with an optimisation
of negative ion formation in hydrogen plasmas which requires knowledge of the plasma parameters. Emission
spectroscopy is introduced as a non-invasive and in-situ diagnostic tool for line of sight averaged plasma
parameters. Diagnostic lines and simplified analysis methods for a variety of plasma parameters, such as electron
density and electron temperature, gas temperature, atomic and molecular hydrogen density as well as cesium
densities (atoms and ions) and negative ion densities are identified and prepared for direct application. Emphasis
is laid on results obtained in RF generated negative ion sources. Correlations of plasma parameters with
extracted negative ion current densities are discussed. Stripping losses in the extraction system are quantified by
using beam emission spectroscopy.
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Synopsis (pdf)