Calculation of thermal diffusivity from measurements with the sine wave modulation method: Modification of Cowan's equations

Cowan's equations have been replaced by an equation giving the thermal diffusivity α of a thin plate uniquely as a function of the measured quantities Δ and δ₀, Δ being the phase difference between the temperature variations at the two faces of the slab and δ₀ the phase difference between the modulated heating beam and the nonheated face. A very simple approximate equation is also proposed for Δ>1.