Single-shot 2-D electron density measurement using laser-collision induced fluorescence data

The laser-collision induced fluorescence (LCIF) diagnostic allows determination of electron density in 2-D from the collision-dependent photon emission of the 33D to 23P transition in He (588 nm). Previous measurements in cathodic arcs with a single intensified camera required imaging many arc operations to remove the background plasma emission and recover the time dependent LCIF response at each camera pixel. This communication presents an improved approach using a fast-framing camera that enables single-shot acquisition of both the plasma emission before the laser pulse arrives and the subsequent LCIF temporal response. Electron density can then be determined in 2-D by solving an optimization problem where the differences between LCIF measurements and collisional-radiative model predictions are minimized. A single-shot LCIF diagnostic will enable study of the stochastic nature of cathodic arcs.