Aluminum multicharged ion generation from laser plasma

Abstract

Multicharged aluminum ions are generated by a ns Q-switched Nd:YAG laser pulse ablation of an aluminum target in an ultrahigh vacuum. Time-of-flight and electrostatic retarding field ion energy analyzers are used to detect the laser-generated multicharged ions. The experiments are conducted using laser pulse energies of 45–90mJ focused on the Al target surface by a lens with an 80-cm focal length to 0.0024cm2 spot area and incident at 45° with the Al target surface. With the increase in the laser pulse energy, a slow increase in the number of ions generated is observed. The generation of ions with a higher charge state is also observed with the increase in the laser pulse energy. For 5kV accelerating voltage applied to the Al target and using laser energy of 90mJ, up to Al+4 with ∼0.65nC total ion charge is delivered to the detector which is located 140cm away from the Al target. Raising accelerating voltage increases the charge extraction from the laser plasma and the energy of multicharged ions.