Strong Coupling between Clusters and Radiation

Abstract

The interaction of clusters with a laser is studied theoretically and computationally both in linear and nonlinear regimes. The enhanced interaction of laser with clustered matter over conventional unclustered one arises first from the uncancelled transverse polarization induced on clusters by the laser and further in a nonlinear regime from the nonharmonic orbits of electrons that are detached from their original cluster. In the nonlinear regime when the electron excursion length becomes greater than the size of the cluster, the orbit of the detached electron becomes highly chaotic and unable to come back to its original position upon periodic cycles of the optical oscillations. This effect is capable of sharply increasing the efficiency of laser absorption. As many or most of electrons are removed from the cluster, ions of the cluster are subject to Coulomb explode, gaining much of the energy of the electrons and thus that of laser. This efficient energy conversion to ions is favorable for high energy components that are useful for a variety of applications, including thermonuclear fusion reactions.