Fig. 1. Schematic of experimental setup.

Fig. 2. Raw XSC data providing spatial and temporal characteristics of the hot-electron-induced Cu Kα radiation in the experiments: (a) and (b) with solid target; (c) with thin foil. In (b) and (c), the origin of the temporal axis is shifted to the laser profile maximum.

Fig. 3. (a) Temporal correlation of laser beam irradiating massive Cu target with the hot-electron (HE)-induced Cu Kα signal. (b) Spatial extent of the hot-electron interaction with the Cu target derived from the XSC signal averaged over the full Cu Kα duration.

Fig. 4. Time-resolved observation of hot-electron generation at laser-irradiated 1 μm-thick Cu foil. The black curve shows the laser temporal profile, the red points measurements, and the red curve an asymmetric double sigmoidal function fit.

Fig. 5. (a) Spatial distribution of Kα emission from a thin target at selected time moments with respect to the laser pulse maximum. The scans are integrated over 50 ps. (b) Time-integrated spatial distribution of the hot-electron-induced Kα emission from a Cu foil.

Fig. 6. Time dependence of the zone of Cu Kα emission from (a) a massive and (b) a thin target (black squares). The red curves represent the distributions of relative intensities of the Kα emission integrated over temporal windows of 50 ps. Laser energy and pulse duration are 557 J and 287 ps in (a) and 466 J and 318 ps in (b).

Fig. 7. (a) Spatial distribution of electron temperature in (x, z) plane at laser pulse maximum t = 0. The results are obtained from the hydrodynamic simulations with CHIC for the case of a massive target. The laser is incident from the right. The dashed white box shows the part of the plasma used for the PIC simulations related to hot-electron generation in Sec. IV C. The dot-dashed white box shows the part of the plasma used for the PIC simulations related to hot-electron transport in Sec. IV D, but for a thin target. (b) Temporal evolution of hot-electron flux obtained from CHIC simulations (blue curve) and PIC simulations (green squares) described in Sec. IV C. The red squares represent experimental data, and the laser pulse profile is shown by the black curve.

Fig. 8. (a) Spatial distribution of electron density (blue), electron temperature (red), and ion flow velocity (black) in the plasma corona along the laser axis. (b) Spatial distribution of plasma mass density (blue), electron temperature (red), and flow velocity (black) in the dense part of the 1 μm-thick foil. All profiles are obtained from the hydrodynamic simulation using CHIC at a time 100 ps after the laser maximum for a massive target (dashed curves) and a thin foil (solid curves). The laser is incident from the right.

Fig. 9. Spatial distribution of plasma density in the (x, z) plane obtained from a hydrodynamic simulation using CHIC of laser interaction with a 1 μm foil 100 ps after the laser maximum. The laser is incident from the right.

Fig. 10. Temporally integrated spectrum of light recorded at the front box boundary in runs A–D with a massive target. The spectrum includes both the laser and the reflected/backscattered radiation.

Fig. 11. Hot-electron energy distribution recorded by the virtual detector during the quasi-steady stage of interaction behind the critical density in runs A–D.

Fig. 12. Distribution of (a) magnetic field B_y and (b) electric field E_x obtained in run E at time t = 30.2 ps.

Fig. 13. Distribution of hot electrons in the (z, p_z) plane, time-averaged from the start of the simulation t = 0 up to time moment t₁ = 10.5 ps (a) and 22.5 ps (b). Arrows indicate the direction of electron motion.

Fig. 14. Time dependence of z coordinate for test particles oscillating in the charge separation field around the target. The larger the oscillation amplitude, the higher is the test particle energy.

Fig. 15. Dependence of the collisional energy loss of electron crossing foil (blue) and the excursion time (red) on the electron energy. The target areal density is 0.9 mg/cm², the hot-electron temperature is 40 keV, and the density 10¹⁶ cm⁻³.