EVOLUTION OF ULTRA-INTENSE, SHORT-PULSE LASERS IN UNDERDENSE PLASMAS

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