Abstract

Conditions are found under which the expansion dynamics of a short-scalelength laser-driven plasma are controlled primarily by the ponderomotive force of the high-intensity laserdriver. It is postulated that this occurs when the laser intensity is such that the average quiver energy of electrons oscillating in the laser field becomes comparable to their thermal energy. To test this hypothesis, a pump-probe experiment was performed to measure the expansion velocity with 250-fs time resolution. The experimental results are found to confirm this prediction as well as the predictions of a 1-D computer model that includes the hydrodynamic fluid coupled to the wave Also discussed are the ramifications of these results on the production of the high-density and temperature plasmas that are required for the generation of bright short-pulse x-rays.

© 1993 Optical Society of America