Hot electron generation in the ultra-intense laser matter interaction at a steep interface

The absorption of ultra-intense laser light in the step-like densities, highly overdense plasma is discussed. To understand absorption physics we performed one-dimensional collisional particle simulation (PICLS1D). These simulations are able to simulate hot electrons generation in the laser plasma interaction, and energy transport thorough the cold resistive plasma. For a high intensity normal incident laser light the absorption is mainly due to $JXB$ absorption. We observed the electrons are trapped in the interaction region by the electrostatic potential, and the $JXB$ force drives the high energy electrons inwards from the trapped region with the frequency $2\omega$. Except these $2\omega$ electron jets there are also large number of leaking electrons with lesser energy and with the frequency $3\omega$, $6\omega$. When we increase the target density, the $JXB$ electron jets start to disappear resulting in to the decrease of total absorption. The physics inhibiting the production of $2\omega$ frequency electrons is discussed. Together with this we have simulated the effects of preplasma, specifically the increased total absorption which leads the production of higher energy electrons.