Transition from unbounded to bounded plasma whistler wave dispersion

Abstract

Whistler wave dispersion measurements are done in a linear magnetized helicon plasma experiment. The waves are excited by an induction loop and detected by movable magnetic probes for a frequency range of 100–800 MHz, corresponding to 0.05–0.9 ωce. The dispersion of whistler waves is measured for various plasma densities and magnetic field strengths. A key issue is to study the transition from an unbounded to bounded plasma wave dispersion. A comparison with theoretically derived dispersion relations is made. For small wavelengths, the dispersion can be described with whistler wave theory for unbounded plasmas whereas for larger wavelengths, the bounded geometry must be taken into consideration. The experimental results agree with theoretical dispersion relations derived for the bounded and the unbounded situation.