Ion acceleration by superintense laser pulses in plasmas

Ion acceleration by petawatt laser radiation in underdense and overdense pl asmas is studied with 2D3V-PIC (Particle in Cell) numerical simulations. Th ese simulations show that the laser pulse drills a channel through the plas ma slab, and electrons and ions expand in vacuum. Fast electrons escape fir st from the electron-ion cloud. Later, ions gain a high energy on account o f the Coulomb explosion of the cloud and the inductive electric field which appears due to fast change of the magnetic field generated by the laser pu lse. Similarly, when a superintense laser pulse interacts with a thin slab of overdense plasma, its ponderomotive pressure blows all the electrons awa y from a finite-diameter spot on the slab. Then, due to the Coulomb explosi on, ions gain an energy as high as 1 GeV. (C) 1999 American Institute of Ph ysics. [S0021-3640(99)00414-4].