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Figure 6: Shadowgraphs of the plasma shockwave at 500 fs, 800 ps, and 16 ns probe delays during multiple pulses ablation. (a1–a3) Shadowgraphs for the third pulse. (b1–b3) Shadowgraphs for the fourth pulse. (c1–c3) Shadowgraphs for the fifth pulse. The laser fluence is 7.27 J/cm2. The dashed line indicates the interface of silicon and air.