Plasma-induced silica-like protection layer formation on C/C–SiC heat-shield materials for re-entry vehicles
Kurt Hirsch, Bernhard Roth, Ingo Altmann, Karl-Ludwig Barth, Herbert Jentschke, Achim Lunk, Uwe Schumacher
The interaction of a plasma flow with a sample of heat-shield material such as C/C – SiC suitable for thermal protection simulates the main features during the re-entry phase of space vehicles. The formation characteristics of a ‘self’ protecting silica-like surface layer are studied in situ by short-time images of a video camera. Band pass filters discriminate the grey emission of the surface against plasma radiation. Formation speeds and times, respectively, as well as a threshold behaviour were determined for different heat loads. Simultaneously the emission of erosion products (Si I, C I) was spectrally resolved and their temporal development recorded. Additional infrared emission spectra of the sample clearly show the development of the silica phonon spectra indicating a growing layer thickness. An analysis of the temporal development of the erosion rate of these materials agrees with the other results and the hypothesis on this self protection behaviour.