Hamburg 2001 – scientific programme

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VA: Vakuumphysik und Vakuumtechnik

VA 2: Vakuummesstechnik

VA 2.4: Talk

Monday, March 26, 2001, 11:50–12:10, R221

Transmission Thermal Wave Measurements of Superinsulation Foils — •J.-L. Nzodoum-Fotsing¹, J. Gibkes¹, A. Haj Daoud¹, I. Delgadillo-Holtfort¹, D. Dietzel¹, N. Marquart², J. Pelzl¹, and B. K. Bein¹ — ¹Experimentalphysik III, Festjoerperspektroskopie, Ruhr-Universitaet Bochum, Germany — ²IBS, Universitaet Dortmund, Germany

Thermal wave measurements, relying on modulated laser heating of the sample’s front surface and IR detection of the thermal response at the rear surface, have been run on superinsulation foils to provide quantitative information on the effective thermal transport properties and heat insulation. The measurements have been done at different ambient pressures, between 10-3 mbar and 300 mbar. The range of the used heating modulation frequencies, 0.03 Hz - 25 Hz, has been chosen in agreement with the low effective heat transport across the measured multi-layer foils, consisting of aluminized mylar foils and spacer layers. The measured data are interpreted using a theoretical model, considering both conductive and radiative heat transport. In the very low frequency limit, the measured amplitudes give information on the attenuation factor with respect to steady-state heat flux. At the intermediate frequencies, information on the effective thermal diffusivity is obtained, both from the thermal wave amplitude and its phase retardation. The radiative heat transport can become more important at the higher modulation frequencies, corresponding to shorter thermal diffusion lengths