Fig. 1. Sketch of the configuration of EOS measurements using the impedance mismatch technique. A streak camera measures the times of the shock arrival; the shock velocities and are calculated from the difference of these times.

Fig. 2. Calculation of the EOS point for carbon from measured and Al Hugoniot adiabat using the impedance mismatch method.

Fig. 3. Laser pulse profiles used in the simulations.

Fig. 4. The dependences of the difference between shock arrivals for Gaussian pulses and the reference one (flat top) from for all three parts of the target: (i) base (Al: ); (ii) Al step (Al: ); and (iii) carbon step (Al–C: ) – and , correspondingly. All dependences are very close to each other for .

Fig. 5. Comparison of spatial profiles for the shocks initiated by flat-top and Gaussian (FWHM duration 300 ps) pulses. Lines 1 and 2 (dashed) are shock profiles for a flat-top laser pulse at 200 and 500 ps (close to the shock breakout on the base and the carbon step). Lines 3 and 4 (solid) are shock profiles for a Gaussian laser pulse at 314 and 614 ps. We notice that both profiles have the same time shift . Despite the profile differences the fronts for both shocks are very close to each other. The laser strikes from the right. Zero on corresponds to the target front. The vertical line at is the initial Al–C interface. Ablation surfaces and Al–C interfaces for flat-top profiles at 200 and 500 ps are indicated (for 200 ps, the Al–C interface is the initial one).