Abstract
Studies on the voltage distribution on the top electrode are important to improve the radio frequency (RF) heating uniformity of samples. The goal of this study was to evaluate the top electrode voltage distribution uniformity in RF systems. The voltages of five representative points on the top electrode were measured by a measuring device with 3 kg soybeans, and validated by the heating patterns using 0.9 kg soybeans located at five positions of the RF cavity. The results showed that the length effect of the copper straps used for connecting the measuring points and measuring device should be taken into account by ignoring little effects of the strap shapes. The final voltages away from the feed strip were higher than those near the feed strip and the deviations between the minimum and the maximum values among the five voltages were 694.3 and 440.9 V, corresponding to the highest voltage difference of 11.99 and 7.12% without and with load, respectively. The real top electrode voltage distribution could be potentially used in computer simulations to achieve the accurate RF heating patterns.
Acknowledgements
We gratefully thank Hankun Zhu, Zhi Huang, Rongjun Yan, Bo Ling, Lixia Hou, and Rui Li for their helps on data processing and suggestions to improve experimental design.