Control of Ionization in the Interaction of Strong Laser Fields with Dense Nanoplasmas

Abstract

Different experimental methods to maximize the yield of highly charged ions in silver and xenon clusters interacting with intense and ultra-short optical laser pulses are discussed. Theoretically, the interaction of strong laser fields with clusters is investigated within the nanoplasma model. The time evolution of the laser intensity has been parametrized. The free optimization of the parameters with a genetic algorithm is an effective but expensive tool to control the plasma dynamics. Comparison is given to the parametric control method in which pulse separation and relative intensity ratio of double-pulses are varied. This method delivers in the case of silver and xenon clusters pulses quite close to the optimal pulse shape.

Influence of excitation and deexcitation processes on the dynamics of laser-excited argon clusters

“…In experim ents, an optim ized yield o f silver ions was found by shaping the am plitude and phase o f tailored laser pulses [67], where the optim ized pulse shape appeared to be a sim ple double-pulse structure. Such a structure was also found num erically with the nanoplasm a model o f Hilse et al, investigating laser-excited silver and xenon clusters [67][68][69]. Because excited states were neglected in these previous w orks, it is interesting to see how the consideration o f excited states in our extended model modifies the ion yield resulting from double-pulse excitation.…”

“…The m axim um o f the ion yield is increased and shifted to larger delay tim es if the ratio o f the peak intensities is decreased. This m eans that, in order to optim ize the ion yield, it is advantageous to use a sm aller prepulse follow ed by a larger main pulse, thus reproducing the optim ized double-pulse char acteristics known from silver clusters [67,69], If excited states are included, the behavior is qualitatively similar. However, by taking excited states into account, m ore A rl3+ ions are produced.…”