Effect of the Response Delay of the Measuring System on Thermal Diffusivity Measurement Using the Flash Method1

This work investigates the effect of the response delay of a measuring system on a thermal diffusivity measurement. A model of an mth-order delay in the measuring system is introduced, and a general expression for the output of the system with temperature response as input is derived. The effect on the tem- perature response caused by such a system is discussed. As a practical example, a third-order measuring system is considered. The measured temperature responses of stainless steel foils are compared with those calculated with the model of a third-order delay system. Good agreement between the two results is shown.