Lawrence Berkeley National Laboratory

A warm fluid model suitable for describing intense laser-plasma interactions is discussed. A momentum space transformation is developed for the Vlasov Maxwell system that leads to significantcomputational savings. Direct numerical solutions of the Vlasov equation are compared to the predictions of the warm fluid model and excellent agreement is found. In particular, it is foundthat, as predicted by the warm fluid, the bulk fields are largely insensitive to the details of the phase-space distribution. The warm fluid is compared to the particle-in-cell model and it is foundthat the latter model, at typical numerical resolution, predicts a momentum spread in the laser that is unphysically large.