Abstract

In plasmas produced by ultrashort-pulse lasers, electron heat transport down steep thermal gradients carries absorbed laser energy away from the plasma and into cold bulk target regions. Supersonic electron conduction is predicted to be the limiting factor for both the peak and the duration of the initial plasma heating.¹ Therefore, a quantitative understanding of electron-energy transport rates and heat-wave details is important to studying these plasmas as high-energy-density, strongly coupled matter and to their application as high-brightness x-ray sources. Hydrodynamic expansion, at the speed of sound, follows most electron conduction, lowering the plasma temperature and density and obscuring the experimental reflection signal. The transition between these two primary plasma energy channels exists on a several- picosecond time scale, which can be probed only by femtosecond pulses.

© 1995 Optical Society of America