Influence of a lowdensity preplasma on high energy electrons generation in ultrashort ultraintense lasersolid interaction

The interaction between an ultrashort ultraintense laser pulse and a solid target with a low density preplasma is examined. Both linear and circular polarizations of the laser are considered. The electrons in the preplasma are accelerated by the ponderomotive force of propagating laser pulse, and the dependences of the maximum electron energy on the laser intensity and the preplasma density are examined. The target electrons are accelerated by ＪＢ mechanism, and the maximum energy achieved is much lower than that of the preplasma electrons. In this sense, the preplasma is advantageous for energetic electrons generation in the ultrashort ultraintense lasersolid interaction.