Diagnostics of picosecond laser pulses using non-linear forces of ponderomotive dynamics

Experiments on electron acceleration by lasers in vacuum have shown that the approximate description of the acceleration by a ponderomotive potential can be extended to a quiver drift description, This more general description is necessary when the general non-linear forces no longer permit a conservative ponderomotive potential. One consequence is that for the simplified conditions of the interaction of an electron beam with a laser beam a modification results in which the electron energy is up or down shifted due to the stochastic phase variation during interaction, Further, an axial displacement of the electron is derived which can be applied to analyse the filamentation (hot spot) properties of picosecond or shorter laser pulses.