Diffraction and the evolution of small scale filaments in a laser-produced plasma

Abstract
Intense laser light filamentation in a hydrogen plasma is investigated using a two-dimensional hydrodynamic simulation code. The laser paraxial wave equation is used to study the focusing which results from a Gaussian hot-spot intensity perturbation. It is found that diffraction increases the scale size of small scale off-axis filamentation, and significantly raises the ponderomotive self-focusing intensity threshold. Radially propagating density fluctuations, contributing to small scale focusing, are observed due to the self-consistent treatment of hydrodynamics in the simulations.