Vacuum electron acceleration by an intense laser

Using three dimensional test particle simulations, the characteristics and essential conditions under which an electron, in a vacuum laser beam, can u ndergo a capture and acceleration scenario (CAS) have been examined. When a (0)greater than or similar to 100 the electron can be captured and violentl y accelerated to energies greater than or similar to1 GeV, with an accelera tion gradient greater than or similar to 10 GeV/cm, where a(0)=eE(0)/m(e)om egac is the normalized laser field amplitude. The physical mechanism behind the CAS is that diffraction of the focused laser beam leads to a slowing d own of the effective wave phase velocity along the captured electron trajec tory, such that the electron can be trapped in the acceleration phase of th e wave for a longer time and thus gain significant energy from the field. ( C) 2001 American Institute of Physics.