Hydrodynamic Modeling of Ponderomotive Force Effects on Electron Density Dynamics in Laser-Plasma Interactions

Abstract

The work listed here reports extensive numerical computational modelling of hydrodynamic processes and the nonlinear, coupled interactions between plasma and high intensity laser EXPLOsions (electron density dynamics are considered as an offshoot of ponderomotive forces) using numerical methods to model the interaction of the laser with plasma using two fluid (Plasma) relativistic hydrodynamic (RHD) codes coupled with time dependent Maxwells equations in order to compute the space-time evolution of the plasma density spatially at different wavelengths (i.e.  ) as a function of laser intensity (I, ) which ranges approximately from . The model examines the relative importance of ponderomotive and thermal electron fluid pressures while providing no physical justification for all relativistic corrections (i.e. electron mass) or influence of static electric fields. The simulations revealed (+) that where conditions are relativistic (I > 10^18 W/cm2), then the ponderomotive force is dominant and ejects a significant number of electrons from the area surrounding the focal point of the laser (which creates an elongate plasma channel which creates an abrupt change in electron scale-free electron density at the plasma surface free electron density). The simulation indicated there is a well defined critical value for the laser to produce (or near produce) the vacuum-like region along the axis of a focused laser beam which contributes to the formation of a slow light region and will enhance self-focusing of the laser beam, (while also); (-) it was also shown that the sharp increase in density associated with the laser beam is a gross modification of the efficiency of resonance absorption. These findings provide critical theoretical insights into the optimization of laser energy deposition for inertial confinement fusion (Fast Ignition) and laser-wakefield acceleration applications.