Method for measuring thermal diffusivity on bulk samples

The measurement of thermal diffusivity on bulk samples has been previously performed using techniques which require a modulated point heating of the surface and a movement of the temperature detector or of the heating source to determine the phase shift of the modulated surface temperature at an increasing distance from the heating source. Such a movement must be realized with great accuracy and can be the cause of many experimental difficulties. The method proposed herewith is based on the fact that the modulated heating of a bulk sample on a surface spot gives a phase shift. between modulated temperature and heating source, which only depends on the ratio between the spot linear dimension and the thermal diffusion length. A frequency sweep produces a variation of the thermal diffusion length and a variation of the measured phase shift between 0degrees and -45degrees, thus allowing for a static single sided measurement of the thermal diffusivity of the sample.