Characteristics of plasma flow from laser irradiated planar thin foil targets

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Abstract
Filamentary structures or jetting in the plasma flow generated from laser irradiated thin foil targets have been observed using an optical probe technique. Laser wavelength, pulse duration, and intensity range used in the experiments were 1.06 μm, 5 ns, and 5×1012 W/cm2, respectively. A 0.53-μm-wavelength optical pulse of 50-μJ energy and 1-ns duration was used as an optical probe. Optical shadowgrams showed that the filamentary structures or jets in the plasma flow were strongest in the region about 300 μm away from the target surface, and in time, much later than the peak of the main laser pulse. It was also observed that jetting does not affect the stability of the ablatively accelerated thin foils. Jetting was found to be stronger for targets with a higher atomic number. A time-resolved interferometric study of the plasma produced from targets with high atomic numbers also showed the existence of an abrupt change in fringe shift or plasma density in the region of these jets.