THERMAL-WAVE MEASUREMENTS OF MULTI-LAYER SUPERINSULATION FOILS

Abstract Thermal wave measurements rely on modulated laser heating and IR detection of the thermal response, using a MCT detector with IR optics and lock-in amplifier. Both, the amplitude and the phase retardation of the thermal wave response with respect to the heating modu-lation, provide information on the effective thermal transport properties of the measured samples. Here we apply this method to determine the shielding properties of multilayer superinsulation foils, used for the thermal insulation of superconducting magnetic coils in particle accelerators, e.g. in LHC at CERN. The measurements, performed at ambient temperature and ambient and reduced pressure, have been interpreted using a theoreti-cal model, including both conductive and radiative heat transport. The results show that the radiative heat transport can be well identified, although the conductive heat transport is dominant across multi-layer samples. At reduced pressures, the conductive heat transport decrea-ses considerably and, depending on the number of spacer layers, the radiative heat transport can become dominant. Applying this new photothermal technique, the shielding efficiencies of multi-layer superinsulation foils have been compared in this work for the first time