Multicharged carbon ion generation from laser plasma

Carbon ions generated byablation of acarbon target using anNd:YAG laser pulse (wavelength λ = 1064 nm, pulse width τ = 7 ns, and laser fluence of 10-110 J cm−2) are characterized.Time-of-flight analyzer, a three-mesh retarding field analyzer, and an electrostatic ion energy analyzer are used to study the charge and energy ofcarbon ions generated bylaser ablation. The dependencies of the ion signal on the laser fluence, laser focal point position relative to target surface, and the acceleration voltage are described. Up to C4+ ions are observed. When no acceleration voltage is applied between thecarbon target and a grounded mesh in front of the target, ion energies up to ∼400 eV/charge are observed. Thetime-of-flight signal is analyzed for different retarding field voltages in order to obtain the ion kinetic energy distribution. Theablation and Coulomb energies developed in the laserplasma are obtained fromdeconvolution of the iontime-of-flight signal.Deconvolution of thetime-of-flight ion signal to resolve the contribution of each ion charge is accomplished using data from a retarding field analysis combined with thetime-of-flight signal. The ion energy and charge state increase with the laser fluence. The position of the laser focal spot affects the ion generation, with focusing ∼1.9 mm in front of the target surface yielding maximum ions. When an externalelectric field is applied in an ion drift region between the target and a grounded mesh parallel to the target, f...

Source: Review of Scientific Instruments - November 14, 2016 Category: Physics Authors: Oguzhan Balki and Hani E. Elsayed-Ali Source Type: research