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 undergo a capture and acceleration scenario (CAS) have been examined. When a(0)greater than or similar to 100 the electron can be captured and violently accelerated to energies greater than or similar to1 GeV, with an acceleration gradient greater than or similar to 10 GeV/cm, where a(0)=eE(0)/m(e)omegac is the normalized laser field amplitude. The physical mechanism behind the CAS is that diffraction of the focused laser beam leads to a slowing down of the effective wave phase velocity along the captured electron trajectory, such that the electron can be trapped in the acceleration phase of the wave for a longer time and thus gain significant energy from the field. (C) 2001 American Institute of Physics.