Theory of energy deposition by suprathermal electrons in laser-irradiated targets.

In this paper we describe results of the preheat generated by the suprathermal electrons from laser-produced plasmas in the cold substrate material. The computations were carried out by means of a Monte Carlo-type code that accounts for the scattering and slow down of the hot electrons in the cold material. Using ideas derived from a straight-line approximation method, the results were described by means of a dimensionless quantity. Such a description results in simple analytical (in fact, exponential) formulas, which are easy for computation and can be readily inserted into hydrodynamics codes. To exemplify the results, we have computed the preheat temperature and pressure in a laser-irradiated aluminum foil. A short discussion is given about the accuracy and the validity domain of the formulas, and a comparison is given to previous analytical methods.