Characterization of ablator dynamics initiated by picket pulse conditions

Direct-drive laser-fusion targets can often include thin films deposited on the plastic ablator shell to provide various functions. An experimental system involving synchronized femtosecond and picosecond lasers of different wavelengths is employed to initiate and characterize dynamics of coated and uncoated polystyrene planar targets irradiated by conditions similar to a “picket” prepulse from a direct-drive pulse shape. Ultrafast imaging of the resulting blowoff plasma expansion and shock-wave propagation is used to compare the impact of different coating configurations. The subsequent damage crater morphologies are also analyzed as evidence of the dynamics of the solid-to-liquid interface expansion. These results may help future efforts to develop laser drivers and target designs that make laser fusion economically viable.