Fig. 1. Scanning electron microscope images of foam targets used in the experiment: (a) TMPTA foam, scale 2 μm; (b) graphene foam, scale 2 μm; (c) AM foam, scale 50 μm.

Fig. 2. Photographs of mounted foam targets: (a) TMPTA foam in a washer; (b) free-standing AM foam on a copper substrate;⁸ (c) overall view of AM target of diameter 0.95 mm and thickness 0.6 mm. (b) Reproduced from Wiste et al., J. Appl. Phys. 133, 043101 (2023). Copyright 2023 AIP Publishing LLC.

Fig. 3. Schematic of diagnostics: soft X-ray streak camera, time-integrated high-resolution X-ray spectroscopy, hard X-ray imager, and probe femtosecond laser pulse.

Fig. 4. Natural logarithm of the signal obtained with a soft X-ray streak camera from (a) TMPTA, (b) graphene, and (c) AM targets at a laser energy of ∼180 J. The signal is normalized to its maximum value. The laser comes from the top, and the time of its arrival on the target is not measured. The horizontal dashed line indicates the position of the target front surface. The oblique solid line denotes the front of the ionizing heating wave and the dotted line the plasma expansion into the vacuum, with both lines being plotted at a level of 2%–3% of the signal maximum. Shot numbers are 58 477, 58 496, and 58 489, respectively.

Fig. 5. Typical spectrum of time-integrated chlorine X-ray emission from a TMPTA target. The broadening of the Cl Heα_y intercombination line is used for the determination of the ion temperature; the variable ratio of Heδ and Lyβ emission indicates the decreasing electron temperature with increasing distance from the target surface from 90 μm (red) to 225 μm (green).

Fig. 6. Far-field view of the transmitted probe beam (a) before and (b) 450 ps after the laser pulse maximum. A laser pulse of energy 187 J interacts with a TMPTA foam of thickness 250 μm. The probe beam is incident at an angle of 30° in the horizontal plane. The origin (0,0) corresponds to the center of the transmitted signal for a calibration shot without any target. The red crosses mark the positions of the signal maxima. Note the difference in the scales in the two figures. The shot number is 60 233.

Fig. 7. Reconstructed images of the Kα₁ emission from (a) graphene, (b) TMPTA, (c) AM, and (d) copper targets at a laser pulse energy of 180 J. The experimental distortion of the copper Kα₁ emitting area due to an oblique angle of observation and the system magnification have been corrected.