COMPUTER-SIMULATIONS OF CATHODELESS, HIGH-BRIGHTNESS ELECTRON-BEAM PRODUCTION BY MULTIPLE LASER-BEAMS IN PLASMAS

The use of two crossed laser pulses in a plasma for the cathodeless pr oduction of high-current low-emittance electron beams [D. Umstadter, J . K. Kim, and E. Dodd, Phys. Rev. Lett. 76, 2073 (1996)] is examined w ith fully relativistic, two-and-a-half-dimensional particle-in-cell si mulations. Estimates for the number of injected particles, their energ y spread, and their emittance are given as functions of the amplitude and timing of the injection pulse relative to the drive pulse of the l aser wake field accelerator. The physical mechanism of the trapping of particles is examined based on single particle phase space trajectori es in the simulations and numerical calculations.