QUALITATIVE MEASUREMENT OF HEATING UNIFORMITY IN A MULTIMODE MICROWAVE CAVITY

Qualitative tests of heating uniformity in a domestic multimode cavity were made using thermal paper. The power distribution in the empty ca vity was non-uniform. A stationary four-bladed mode stirrer modified t he distribution; rotation at 5 rpm improved uniformity. A cylindrical quartz reactor and alumina-silica insulating cylinder were placed in t he cavity, concentrating the field in the reactor and insulation. The field was stronger at the bottom of the empty reactor. Stainless steel sheathed thermocouples in the reactor perturbed the field slightly. W hen the reactor was filled with granular activated carbon the field wa s concentrated at the top of the reactor.