In this paper, we have successfully developed a multi-magnetron multi-mode high-temperature furnace for material processing. The SiC crucible could be heated to 1000 oC within only a few minutes. Synthesis of thermoelectric Al-doped ZnO in a microwave furnace took less than 20 times the time of a conventional furnace, and the electric power of Al-doped ZnO was higher. The furnace was fabricated according to the computational optimization using Comsol. Two waveguides were mounted on opposite sides of the cavity must have 90 degree relative angle. For impedance matching and power combination, the multi-mode rectangular cavity must have dimensions of 28 x 28 x 28 cm3 . Therefore, electric fields were maximized at the center of the cavity and minimized in the waveguides. To suppress the microwave leakage within safety standards, choke parameters were obtained. The calculations and measurements reinforce that scaling up can be done in the future.
