Measurements of thermal diffusivity for thin slabs by a converging thermalwave technique

The measurement of thermal diffusivity for thin slabs by a converging therm al have technique has been studied. Temperature variation at the center of the heat source ring that is produced by a pulsed high-power laser is detec ted by an infrared detector. A computer program based on the finite differe nce method is developed to analyze the thermal diffusivity of the slabs. Ma terials of both high thermal diffusivity (CVD diamond wafer) and loa therma l diffusivity (stainless-steel foil) have been used for the measurements. T he measurements have been performed bq varying the size and the thickness o f specimen. The converging thermal wave technique has proved to be a good m ethod to measure the thermal diffusivity of a CVD diamond without breaking the wafer into small specimens. The technique can be applied For a small sl ab if the diameter of the slab is two times larger than that of the heat so urce ring. The sensitivity of thickness in measuring the thermal diffusivit y is low for ordinary CVD diamond. The use of the converging thermal wave t echnique for nonhomogeneous, nonuniform, and anisotropic materials has been accomplished by applying the finite difference method.