Investigation of ion dynamics and acoustic wave propagation in dipole-confined plasma

Understanding plasma behavior in the dipole magnetic field geometry is important for various naturally-occurring and laboratory plasma environments. Charged particles in this geometry undergo more general particle trajectories than in straight-line magnetic fields, including chaotic orbits. An environment with such general particle motion provides a test-bed for electrostatic wave-scattering experiments in a plasma. Ion acoustic waves are launched far from a permanent dipole magnet and waves mode convert into electrostatic ion cyclotron waves as they approach the magnet. Waves may be reflected, absorbed, or scattered from plasma near a dipole magnet. Laser-induced fluorescence (LIF) techniques provide diagnostic methods for describing ion dynamics in low-temperature plasma as well as the ion response to electrostatic perturbations. In addition to cold and emitting Langmuir probes, LIF measurements are presented for the first time in a dipole magnetic field geometry to characterize the argon ion dynamics as well as ion acoustic wave scattering from dipole-confined plasma.