Efficient laser-overdense plasma coupling via surface plasma waves and steady magnetic field generation

The efficiency of laser overdense plasma coupling via surface plasma wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed over a wide range of laser pulse intensity from 10(15) to 10(20) W cm(-2) mu m(2) with electron density ranging from 25 to 100n(c) to describe the laser interaction with a grating target where a surface plasma wave excitation condition is fulfilled. The numerical studies confirm an efficient coupling with an enhancement of the laser absorption up to 75%. The simulations also show the presence of a localized, quasi-static magnetic field at the plasma surface. Two interaction regimes are identified for low (I lambda(2) < 10(17) W cm(-2) mu m(2)) and high (I lambda(2) > 10(17) W cm(-2) mu m(2)) laser pulse intensities. At "relativistic" laser intensity, steady magnetic fields as high as similar to 580 MG mu m/lambda(0) at 7 x 10(19) W cm(-2) mu m(2) are obtained in the simulations. (C) 2011 American Institute of Physics