Temporal evolution of the state of local thermodynamic equilibrium of a laser produced plasma at low fluence

Summary form only given, as follows. Of the few studies that have been devoted to examining departure from LTE conditions, several suggest that laser produced plasmas at low fluences could be far from LTE at early times (before typically 1 /spl mu/s). The present work addresses this issue by investigating the departure from LTE conditions in Al plasmas created by a 10 ns excimer laser pulse at a wavelength of 308 nm with fluences of about 10 J/cm/sup 2/. The Boltzmann diagram method is applied to a few lines emitted by iron impurities contained in an Al matrix. Time evolution of the LTE departure is investigated by probing the plume at various delays after the laser pulse interaction with the target.