Effect of Directional Nature of Antenna and Magnetic Field Strength on Optimal Power Absorption in a Helicon Discharge

The study of power absorption in a helicon plasma source excited by 13.56 MHz frequency is reported. Numerical analysis is carried out to determine the power absorption in helicon discharge for m = +1 mode, considering both helicon and electrostatic Trivelpiece–Gould (TG) waves. The effects of electron density, external magnetic field strength, parallel wave number, antenna type and antenna length on the power absorption are investigated. The power absorption is obtained by considering that the radio frequency (RF) wave propagates in uniform plasma in a constant magnetic field. Maxwell’s equations are solved in the plasma and vacuum regions using boundary conditions to obtain the amplitude of the helicon and TG waves. It was found that higher power is absorbed in case of half-helical antenna due to its asymmetric nature as compared to Nagoya Type 3 antenna of the same length. Moreover, an optimization of parameters involving antenna dimensions, propagation vector, and external magnetic field strength, was estimated for optimal power absorption in a helicon discharge.