The Effect of Cross-sectional Area of The Microwave Argon Discharge Tube on Some Plasma Parameters using COMSOL Multiphysics

Microwave plasma plays a vital role in various scientific and technological applications due to its high efficiency and flexibility. The geometry of the discharge tube, especially its cross-sectional area, significantly affects essential plasma parameters such as electron density, ion density, and electron temperature. These parameters directly influence plasma behaviour, including energy absorption and electromagnetic field distribution. This study employs COMSOL Multiphysics software to analyze how variations in the cross-sectional area of the discharge tube impact plasma characteristics. The objective is to identify patterns that could improve the design and performance of plasma-based systems, with potential benefits in fields like medical tissue purification, environmental applications, and manufacturing. The tube had a constant length of 25 cm and varying widths between 1 and 14 cm, resulting in cross-sectional areas from 25 to 350 cm². The results revealed that increasing the area notably affects thermal stability, energy distribution, and plasma penetration. Electron density and temperature changed with the area; the highest electron density was 2.05×10¹⁸ m⁻³ at 175 cm². Electron temperature varied between 1.5 eV at 100 cm² and 1.75 eV at 25 cm², peaking at 1.65 eV at 175 cm².