Coulomb explosion at low and high ion velocities

The ion-induced electric field is calculated for estimating the effect of the Coulomb explosion (CE) mechanism. The increase of the kinetic energy of lattice ions in the electric field of the track core is Δε ∝ (q(0))4, where q(r) is the induced initial charge density. Estimates are made for the irradiation of SiO2 by 2 MeV/nucleon Kr beam: the mean energy of lattice ions reaches 8.1 eV within 4 fs in the track core. The Lorentzian and Gaussian charge density distributions lead to similar results. The type of solids affects Δε through the charge neutralization time. As a result of the decrease of q(0), Δε is reduced by about an order of magnitude in the range 2–8 MeV/nucleon. The projectile velocity may affect the formation of ion-induced tracks by the CE mechanism.