Fast electrons from electron-ion collisions in strong laser fields

Electron-ion collisions in the presence of a strong laser field lead to a distribution of fast electrons with maximum energy E-max=(k(0)+2v(0))(2)/2(a.u.), where k(0) is the impact and v(0) the quiver velocity of the electron. The energy spectrum is calculated by two approaches: (1) The time-dependent Schrodinger equation is numerically solved for wave packet scattering from a one-dimensional softcore Coulomb potential. Multiphoton energy spectra are obtained demonstrating a separation of the energy spectrum into an exponential distribution for transmission and a plateau distribution for reflection. (2) The energy spectrum is analytically calculated in the framework of classical instantaneous Coulomb collisions with random impact parameters and random phases of the laser field. An exact solution for the energy spectrum is obtained from which the fraction of fast electrons in the plateau region can be estimated. (C) 2005 American Institute of Physics.