Direct observation of the ponderomotive force effects in short-scale-length laser plasmas by frequency-domain interferometry - art. no. 056412

We report on single-shot frequency-domain interferometric measurements show ing space- and time-resolved ponderomotive electron density profile steepen ing of a short-scale-length ultraintense laser-produced plasma. The density gradient scale length is varied by applying a time-delayed laser prepulse. The measured absolute position of the critical density surface is found to be in agreement with one-dimensional hydrodynamic simulations for the rang e of scale lengths studied.