The Ponderomotive Force on a Charge q Moving in an Electromagnetic Field

Equations of motion of a single charged particle are derived to second order in E where E is an electromagnetic field. By averaging over the wave-period we find the ponderomotive force on the particle. This force may lead to a transport of matter as is also the case in ordinary hydrodynamics. There the effect is called acoustic streaming. We also suggest that the well-known Landau damping may be considered as beeing due to a ponderomotive force.