|Kapitza resistance and thermal conductivity of Kapton in superfluid helium|
We have determined simultaneously the Kapitza resistance, Rk, and the thermal conductivity, ê, of Kapton HN sheets at superfluid helium temperature in the range of 1.4 – 2.0 K. Five sheets of Kapton with varying thickness from 14 µm to 130 µm, have been tested. Steady-state measurement of the temperature difference across each sheet as a function of heat flux is achieved. For small temperature difference (10 to 30 mK) and heat flux density smaller than 30 Wm-2, the total thermal resistance of the sheet is determined as a function of sheet thickness and bath temperature. Our method determines with good accuracy the Kapitza resistance, RK=(10540+/-444) T-3 x10-6 Km2W-1, and the thermal conductivity, ê=[(2.28+/-0.54)+(2.40+/-0.32)xT ]x 10-3 Wm-1K-1. Result obtained for the thermal conductivity is in good agreement with data found in literature and the Kapitza resistance’s evolution with temperature follows the theoretical cubic law.