Strongly anisotropic ion emission in the expansion of Nd:YAG-laser-produced plasma

We present results from a combined experimental and numerical simulation study of the anisotropy of the expansion of a laser-produced plasma into vacuum. Plasma is generated by nanosecond Nd:YAG laser pulse impact (laser wavelength [Formula: see text]) onto tin microdroplets. Simultaneous measurements of ion kinetic energy distributions at seven angles with respect to the direction of the laser beam reveal strong anisotropic emission characteristics, in close agreement with the predictions of two-dimensional radiation-hydrodynamic simulations. Angle-resolved ion spectral measurements are further shown to provide an accurate prediction of the plasma propulsion of the laser-impacted droplet.