Absolute energy distributions of Al, Cu, and Ta ions produced by nanosecond laser-generated plasmas at 1013 W cm−2

Abstract

The charge state and energy distributions of ions produced by a pulsed 1 J, 9 ns Nd:YAG laser focused onto solid aluminum, copper, and tantalum targets were measured with an electrostatic analyzer coupled with a windowless electron multiplier detector. Special attention was paid to the detector response function measurements and to the determination of the analyzer transmission. Space charge effects are shown to strongly affect this transmission. Measured absolute energy distributions are presented for several charge states. They follow Boltzmann-like functions characterized by an effective ion temperature and an equivalent accelerating voltage. These parameters exhibit power laws as a function of I λ2 which open the possibility to predict the expected shape of the relative energy distributions of ions on a large range of laser intensities (106–1016 W cm−2 μm2).