High energy negative ion generation by Coulomb implosion mechanism

Generation of high energy negative ions from laser plasmas by Coulomb implosion mechanism is investigated. When clusters or underdense plasmas are irradiated by an intense laser pulse, positive ions are accelerated inside the clusters or in the self-focusing channel by the Coulomb explosion. This could lead to the acceleration of negative ions toward target center. The maximum energy of negative ions is typically several times lower than that of positive ions. A theoretical description and corresponding particle-in-cell simulations of Coulomb implosion mechanism are presented. We show the evidence of the negative ion acceleration observed in our experiments using high intensity laser pulse and the cluster-gas targets.