Generation of Hot Solid-Density Plasmas by Laser Radiation Pressure Confinement

We report here on the effective confinement by the ponderomotive force of a plasma created by an intense, short, $S$-polarized laser pulse incident on a solid aluminum target. Our conclusions are supported by hydrodynamics simulations, postprocessed with detailed spectroscopy and Stark line broadening calculations, and compared with experimental data. To produce this new kind of dense laboratory plasmas, results indicate the existence of an optimum in the laser irradiance which is around (5-7) × ${10}^{17}$ W/${\mathrm{cm}}^2$ while the confinement needs a FWHM greater than 300 fs to be effective.