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P: Plasmaphysik

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

P 12.14: Poster

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

In Situ Determination of Erosion Rates by Application of Emission and Absorption Spectroscopy — •I. Altmann, S. Quell, K. Hirsch, B. Roth, J. Schneider, and U. Schumacher — Institut für Plasmaforschung, Pfaffenwaldring 31, 70569 Stuttgart

The capability of compound materials as heat protection on reentry space vehicles is investigated in a plasma jet experiment supported by the SFB 259. Therefore the erosion rate of C/C-SiC is determined in situ by spectroscopic measurements. It is calculated from the optical depth with respect to the flux geometry. The optical depth is evaluated from consistent effects of self–absorption in ratios of line integrals, widths, maxima and curvatures visible in a SiI triplett at 251nm. These results show good agreement with results of transmission and of gravimetric measurements, as well.

Two dimensional visualizations of relative temperature spread are used to investigate the interaction region on the target surface. Rise and fall of the erosion rate down to an asymptotic value can be explained by a natural protection layer, which develops within a few seconds after the first contact of the target with the plasma jet. Propagation of reaction fronts are resolved.