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Figure 5: Time-resolved plasma shockwave expansion at probe delays on nanosecond timescale. (a–d) Shadowgraphs for the first pulse. (e–h) Shadowgraphs for the second pulse. The dashed line indicates the interface of silicon and air. (i) Measurements of longitudinal and radial expansion of the silicon shockwave as a function of time for the first two pulses ablation of silicon. (j) Calculated longitudinal velocities of silicon shockwave as a function of time for the first two pulses ablation of silicon. (k) Double logarithmic fitting of longitudinal and radial expansion for the first two pulses ablation. The laser fluence is 7.27 J/cm2.