The influence of laser ablation plume at different laser incidence angle on the impulse coupling coefficient with metal target

A calibrated pendulum measuring device and a dimensionless analysis method were used to measure the impulse coupling coefficient at different laser intensities withaluminum, steel, andiron targets. The experiment was performed with a pulsed laser with the wavelength of 1.06μm and the pulse duration of 7 ns. The experimental measurements of the variation of the impulse coupling coefficient versus the laser energy density agree with thetheoretical prediction, and the optimum laser energy density correlated with the maximum impulse coupling coefficient corresponding to thetheoretical predictions. The impulse coupling coefficients with laser incidence angles of0° and  45° are compared for understanding of theeffects of theablation plume on the impulse couplingeffect, and the experimental result shows that the impulse couplingeffect grows as the incidence angle changes from 0° to 45°. Furthermore, the transmittance of the incident laser through theablation plume in front of the target is deduced from the impulse measurements, and theeffect of theablation plume on the impulse coupling at high laser intensity is discussed. In order to investigate the weak impulse couplingeffect, which is difficult to obtain from the experiments, the impulse coupling coefficient at low laser energy density was calculated by the finite element simulation.

Source: Journal of Applied Physics - December 2, 2016 Category: Physics Authors: Xiong-Tao Zhao, Feng Tang, Bing Han and Xiao-Wu Ni Source Type: research