Effects of nonthermal electrons on plasma expansion into vacuum

Summary form only given. The expansion of semi-infinite plasma into vacuum is analyzed with a hydrodynamic model for cold ions assuming electrons initially modelled by a kappa-type distribution. Similarly to Mora study of a plasma expansion into vacuum [Mora P., Phys. Rev. Lett. 90, 185002 (2003)], we formulated empirical expressions for the electric field strength, velocity and position of the ion front in one-dimensional nonrelativistic, collisionless isothermally expanding plasma. Analytic expressions for the maximum ion energy and the spectrum of the accelerated ions in the plasma were derived and discussed to highlight the nonthermal effects on plasma dynamics. This study is of interest in the context of the investigation of mono-energetic ion beams from intense laser interactions with plasmas.