Positivity Preservation in the Simulation of Relativistic Laser-Plasma Interaction

With standard schemes, the plasma density in the hydrodynamic model for relativistic laser-plasma interaction can become negative. Therefore, we present a new scheme that preserves the positivity of the plasma density while still satisfying the conservation of mass. The numerical results for a vacuum-plasma transition of a laser pulse in one and two dimensions compare very well to the results from a standard PIC code, but the computation time is greatly reduced.