Impact of thermal shielding on heating efficiency of SiC in single mode microwave resonant cavity

Microwave heating of a susceptor in the form of SiC disc was simulated in a single mode resonant cavity. The microwave applicator consisted of a waveguide of rectangular cross section WR340 excited by dominant TE10 mode at the industrial frequency 2.45 GHz. Heating efficiency was investigated in two principal configurations represented by 1) an exposed susceptor and 2) a susceptor surrounded with thermal shielding in the form of three coaxial tubes of microwave transparent ceramics. It was found that a relatively high value of the real part of dielectric permittivity of the insulation ceramics leads to a non-negligible modification of the field pattern inside the cavity. This could significantly improve heating efficiency. Consequently, for the design of an efficient microwave applicator, actual sample as well as insulation geometry and dielectric properties should be highly regarded. The analysis has been supported by experiment.