Electron jets produced by ultrashort laser pulses

The mechanism of fast particle generation by a single p-polarized laser beam of ultrashort pulse duration is analyzed analytically for arbitrary angle of incidence. Nonlocal electron transport that is first and second order in the driving fields is identified as being responsible for the production of groups (jets) of fast particles. It is demonstrated that nonlocal second-order transport produces electron jets twice per cycle while nonlocal first-order transport produces jets only once per cycle. The electron energies obtained by first-order transport can considerably exceed those obtained by second-order transport. The non-Maxwellian structure of the time-resolved electron distribution function is given.