Tracking Plasma Dynamics With Time-resolved Laser Diagnostics

Christopher Young, Stanford University

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.

Abstract Author(s): C.V. Young, A.L. Fabris, M.A. Cappelli