Evolution of ultra-intense, short-pulse lasers in underdense plasmas

The propagation of short-pulse lasers through underdense plasmas at ultra-high intensities (I greater than or equal to 10(19) W/cm) is examined. The pulse evolution is found to be significantly different than it is for moderate intensities. The pulse breakup is dominated by leading edge erosion and plasma wave wake formation rather than from Raman forward scattering type instabilities. A differential equation which describes local pump depletion is derived and used to analyze the formation and evolution of the erosion. Pulse erosion is demonstrated with one dimensional particle in cell (PIC) simulations. In addition, two dimensional simulations are presented which show pulse erosion along with other effects such as channeling and diffraction. Possible applications for plasma based accelerators and light sources are discussed. (C) 1996 American Institute of Physics.