Semi-analytical fluid study of the laser wake field excitation in the strong intensity regime

Wepresentananalyticalandnumericalstudyoftheinteractionofamulti-petawatt,pancake-shaped laser pulsewithanunmagnetizedplasma.Thestudyhasbeenperformedintheultrarelativisticregimeof electron jittervelocities,inwhichtheplasmaelectronsarealmostcompletelyexpelledfromthepulse region. Thecalculationsareappliedtoalaserwake field accelerationschemewithspecifications that may beavailableinthenextgenerationofTi:Salasersandwiththeuseofrecentlydevelopedpulse compression techniques.Asetofnovelnonlinearequationsisderivedusingathree-timescaledescrip- tion, withanintermediatetimescaleassociatedwiththenonlinearphaseoftheelectromagneticwave and withthespatialbendingofitswavefront.Theydescribe,onanequalfooting,boththestrongandthe moderatelaserintensityregimes,pertinenttothecoreandtotheedgesofthepulse.