FORCES ON ATOMS IN LASER FIELDS WITH MULTIDIMENSIONAL PERIODICITY

A description is given of a method for calculating forces on atoms from periodic laser fields in an arbitrary number of dimensions. A crucial approximation is the introduction of an average force which depends on the magnitude and direction of the particle velocity but not on position. A simple two-dimensional example is studied and a strong force component perpendicular to the two-dimensional atomic velocity is found. It may become of interest for the construction of well collimated atomic beams of high intensity. Fluctuations are not included but results from simulations at high laser intensity indicate that average forces alone serve as useful guides in the prediction of modifications of velocity distributions.