Electron Acceleration In Wakefield And Supra Bubble Regimes By Ultraintense Laser With Asymmetric Pulse

With the rapid development of laser technology, laser-plasma particle accelerationis an attractive alternative way to conventional particle acceleration. A great numberof research have shown that laser-plasma nonlinear interaction can provide a high fieldgradient for particle acceleration as well produce a high quality particle beam. It is wellknown that among many laser-plasma acceleration mechanisms, laser wakefield accelera-tion, first proposed by Tajima and Dawson in 1979 , becomes more and more promisingto get high electrons energy, due to it can sustain higher electric field than that in con-ventional accelerators. Esirkepov et al. studied theoretically the acceleration of chargedparticle in the first cycle of the wakefield of symmetric Gaussian laser pulse. RecentlyGeyko et al. have made some fruitful research on this snow-plow acceleration.In this paper electron acceleration in plasma driven by circular polarized ultraintenselaser with asymmetric pulse are investigated analytically and numerically in terms ofoscillation-center Hamiltonian formalism. Studies include wakefield acceleration whichdominates in blow-out or bubble regime and snow-plow acceleration which dominatesin supra-bubble regime. By a comparison with each other it is found that snow-plowacceleration has lower acceleration capability. In wakefield acceleration, there exists anobvious optimum pulse asymmetry or/and pulse lengths that leads to the high net energygain while in snow-plow acceleration it is insensitive to the pulse lengths. Power and linearscaling laws for wakefield and snow-plow acceleration respectively are observed from thenet energy gain depending on laser field amplitude. Moreover, there exists also an upperand lower limit on plasma density for an efiective acceleration in both of regimes.