Evaluating the top electrode voltage distribution uniformity in radio frequency systems

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.

Keywords:

• RF
• top electrode voltage
• distribution uniformity
• copper strap
• soybean

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.

Additional information

Funding

This research was conducted in College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, China and supported by research grants from PhD Programs Foundation of Ministry of Education in China [grant number 20120204110022]; Program of Introducing International Advanced Agricultural Science and Technologies (948 Program) of Ministry of Agriculture of China [grant number 2014-Z21]; General Program of National Natural Science Foundation in China [grant number 31371853].