2.2 Experimental Process
The microwave magnetrons were first powered on to start the heating of the SiC bed, with four magnetrons of the ten started at each test. The microwave leakage was detected to be less than 0.1 mW/cm2 in the area beyond the distance of 0.05 m from the device, which meet the international safety standards [23]. The real time temperature for the SiC bed surface (74,800 pixels points totally) was recorded online by the infrared thermal imager. The thermocouple located at the center of the bed surface was used for temperature control. Microwave heating SiC bed was investigated in the thermocouple controlling temperature range of 95-105 °C, 195-205 °C, 295-305 °C, 395-405 °C, and 495-505 °C respectively. Taking the temperature range of 95-105 °C as an example, the microwave magnetrons were powered on when the temperature detected by the thermocouple was below 95 °C and powered off once the monitored temperature was above 105 °C. The measurement for each temperature range was carried out by continuously repeating the cycle of temperature rise and drop for ten times. For comparison purpose, the temperature and electric field distributions of the SiC bed surface were simulated using a multiphysics software. The details for the simulation can be found in our previous report [11].