Nonadiabatic ponderomotive barriers

Summary form only given. A ponderomotive potential is an effective potential seen by a particle in AC field in average over the fast oscillations. It is not a true potential though, and, if the field scale is small enough, the particle drift center exhibits irreversible motion. In particular, such nonadiabatic dynamics is observed if the AC field is in resonance with particle natural oscillations. An approximate integral of particle motion is found for this case, and a new ponderomotive potential is introduced accordingly. The new potential is non-local, which makes the particle drift similar to the motion of a quantum object in a conservative field. Because of the irreversibility of the effective potential, a resonant barrier can also produce a ratchet effect by asymmetrically transmitting thermal particles in a preferential direction. Possible applications of this and related effects comprise current drive, selective separation and cooling of plasma species, and others