Characterization of the resonant electromagnetic mode in helicon discharges

This paper presents experimental evidence for the existence of a resonant electromagnetic mode in a helicon plasma, and characterizes its resonant frequency, energy absorption rate, and contribution to the overall power balance. An experimental method developed to detect and characterize the plasma impedance is introduced. Power flow analysis shows that the resonant electromagnetic mode is the dominant mechanism driving helicon plasma discharges in cylindrical geometry. The weakly damped wavefields are absorbed in a short distance, indicating that the wavefields may be trapped in a potential well created by a density gradient.