Improvements in the Dynamic Plane Source Method

Three sources of errors in the extended dynamic plane source (EDPS) method caused by the discrepancy between experiment and model are analyzed. The source effect is eliminated by introducing the nuisance parameter R (0) and the surface effect by a surrounding vacuum. The original model assumes a constant heating power but a constant current is used in the experiment. Suppression of this effect leads to a new solution of the heat equation designated as the constant-current model. The measurements on polymethylmetacrylate (PMMA) in vacuum, evaluated by the constant-current model, provided results of lambda = 0.191 W.m(-1).K(-1) and a = 0.118 x10(-6) m (2).s (- 1), which are in good agreement with published values. The total standard uncertainty was estimated as 1.5 % for both thermophysical properties.