Comparison between time-of-flight measurements and numerical simulations for laser-generated plasmas

The modeling of laser-generated plasmas can be carried out by means of different theoretical approaches. Hydrodynamic simulations have the advantage of treating the plasma as a continuous fluid that expands in vacuum with a high Mach number. We used the analytical Anisimov model for the numerical simulations of a plasma expanding at supersonic velocities. The model describes the plume by means of a special solution of the gas dynamical equations on the hypothesis that the flow expands adiabatically. Here, we carry out a comparative analysis between experimental and numerical results: the model fits the experimental data for monoatomic plumes quite well. More specifically, the numerical data have been tested by comparing the time-of-flight signals obtained at the INFN-LNS in Catania from a pure metallic target. A Coulomb drift velocity was added to the expansion velocity, and only in this way was it possible to explain the experimental results, thus confirming the presence of self-generated electrostatic fields inside the expanding plasma plume.