Tracking Plasma Dynamics With Time-resolved Laser Diagnostics
The charged particles found in plasmas are fundamental to both the utility of plasmas for a variety of applications and their inherent complexity. Ions are often heated and accelerated (e.g. through magnetic confinement and application of a potential gradient), leading to complicated distribution functions and spectral lineshapes that evolve in both space and time. Additionally, because plasmas are inherently unstable and support a wide range of oscillations, time-resolved diagnostics are necessary to obtain a full physical picture. This talk describes efforts at the Stanford Plasma Physics Laboratory to construct non-intrusive, time-resolved, continuous-wave laser-induced fluorescence diagnostics for measuring ion dynamics in a variety of systems without perturbing the plasma with physical probes. Two methods that achieve time resolution by locking onto quasi-repeatable current oscillations are evaluated in a 60 Hz test discharge and verified against a collisional-radiative model of excited neutral xenon. Example results from an ExB plasma accelerator demonstrate the power of these methods for obtaining fine detail about the underlying physics in such devices.