Method to Measure the Dielectric Parameters of Powders in Subterahertz and Terahertz Ranges

On the base of the high quality Fabry-Perot resonator a method for measuring dielectric parameters, namely, the refractive index (n) and tanδ values of powder materials, which does not require the measurement of the poured layer thickness, has been developed. The results of measuring the Al
₂
O
₃
, TiO
₂
, ZnO, SnO, and WO
₃
metal oxide powders in the frequency range 160-253 GHz and in the temperature range 20-360 °C are presented. The method was developed and tested for a detailed understanding of the processes of powders heating and evaporation under the radiation influence of high-power terahertz (submillimeter) gyrotrons with subsequent condensation in the form of highly pure nanopowders.