Effect of Pulse Width on the Measurement of Thermal Diffusivity of Metals

Abstract

An effect of pulse width, on themeasurement of thermal diffusivity of metals which is not usually taken into account in the conventional formulas, is discussed under the condition of linear flow of heat. In this paper it is reported that the correction to be applied to the method of determination of thermal diffusivity is obtained by solving heat equations having boundary conditions of input heat flux which has a finite pulse width.
The values of thermal diffusivity obtained by the use of the conventional formulas with an assumption of impulse response have some shifts towards values smaller than the correct ones and the shifts can be estimated by the ratio of the pulse width to the lapse of time from the injection of heat pulse to the instant of temperature measurement which are performed at two points.
The above method is shown to be consistent as the result of the measurement on copper.