Aachen PK 2003 – wissenschaftliches Programm

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P: Plasmaphysik

P 10: Poster II

P 10.25: Poster

Dienstag, 18. März 2003, 17:30–19:15, Foyer

Determination of electron temperature and electron density from intensity ratios of Si I lines — •Ronnie Stirn, Hirsch K., Lindner P., Roth B., and Schumacher U. — Institut für Plasmaforschung, Universität Stuttgart, Pfaffenwaldring 31, D-70569 Stuttgart

Future spacecraft systems ought to be reusable for many flights without a high expenditure of cost and maintenance. One of the most important problems to be solved is the high erosion of the heat shielding material at components with high thermal loads. These high thermal loads occur during the re-entry process at an altitude of about 80 km. One of the most promising materials is the fiber reinforced compound material C/C-SiC. For the basic understanding of the erosion processes it is necessary to know the plasma parameters electron temperature and electron density in the interaction zone of the plasma with the material.

In this work the electron temperatures and densities are determined by line intensity ratios of the erosion product silicon. Presently the Si I singlet lines at 263,13 nm and 288,16 nm as well as the multiplet at 251 nm are used, taking the self-absorption into account, and other lines are investigated concerning their suitability. It was necessary to carry out a collisional-radiative calculation for silicon, and therefore we had to calculate the electron collisional excitation cross sections by R-matrix calculations. The obtained results for the densities and temperatures in the interaction zone are in good agreement with the laser Thomson scattering values.