Emission enhancement in laser-produced plasmas on preheated targets

Laser-induced plasma was produced on preheated (up to 500 °C) aluminum targets in air with a nanosecond-pulsed Nd:YAG laser emitting at 1064 nm. Plasma was generated for laser pulse energies ranging from 60 to 800 mJ and the spatially and time-integrated emission was collected as the sample temperature was increased. Electron temperature was found to be independent of the experimental conditions, while the electron density had a weak dependence on the pulse energy and target temperature. Emission enhancement increased with both varied parameters, although with a tendency to saturation for high-energy and high-temperature regimes. A simple model predicting the ablated volume is discussed in terms of the experimental results.