Research On Explosion Dynamics Of Heteroclusters In Ultraintense Femtosecond Laser Pulses

With the development of laser technique, studies on the interaction of intense laser with matter, especially with cluster, reach a new level. The laser energy can be efficiently absorbed by cluster jet due to its unique characteristics. Systematic researches on the interaction of cluster with femtosecond laser pulses have been done by many research groups. Since table-top nuclear fusion resulted from explosions of deuterium clusters in intense femtosecond laser pulses realized experimentally in 1999, how to improve the energy of deuterium ions to increase the yield of neutrons, has attracted much attention.In this paper, using Bethe model, the explosion dynamics of heteroclusters ((CH4)n,(CD4)n,(D2O)n) in ultraintense femtosecond laser pulses (I=1017-1020 W/cm2) has been studied theoretically. The research results are as follows:Firstly, in ultra-intense laser field, the explosion of heteroclusters shows distinct characteristcs from that of homoclusters. It is found that the average kinetic energy of the ions (H+,D+,C4+ and O4+) from heteroclusters is proportional to the square of the initial cluster radius, the explosion mechanism is typical coulomb explosion.Secondly, for both heterocluster and homocluster which have the same amount of hydrogen (or deuterium) atoms, the kinetic energies of H+(or D+) ions from hetrocluster after explosion in the ultraintense laser pulses are remarkably higher than that from homonuclear clusters, indicating that highly ionized ions of high Z element have a strong acceleration effect on the ions of lower Z element.Thirdly, the ion energy spectra obtained from the theoretic simulation is in good agreement with experimental results, when the distributions of laser intensity and cluster size are all taken into account.The research results show that the explosion process of heteroclusters in femtosecond laser field can be simulated using Bethe above-barrier model. It is demonstrated evidently that higher energy deuterium ions can be obtained making using the interaction of hetroclusters with ultraintense laser pulses, accordingly, making it possible to increase the neutron yield from laser driven nuclear fusion effectively. The simulation results are useful to the experimental research of laser driven nuclear fusion.