Design of a High-Efficiency Dual-Helical Antenna for Microwave Plasma Sources

Achieving a sustainable dense plasma source has always been of broad interest. Notably, in microwave discharges, gaining dense uniform plasma has held numerous efforts. In this article, a high-efficiency dual-helical antenna for microwave plasma source to improve the performance of the Alborz Tokamak neutral beam injection (NBI) system is presented. For evaluation and analysis of the designed antenna and a conventional rod antenna, COMSOL Multiphysics software is used. Besides, by feeding the antenna using a 2.45-GHz magnetron in the 20-Pa vacuum steel enclosure and the Argon gas injection, a practical experiment has been conducted. Finally, the plasma with a density of 5.5\times 10^{17}\,\,1/\text{m}^{3} and the electric field intensity results show that the designed antenna is an optimal alternative in microwave plasma sources.