Description
Hot-electron generation and transport play a central role in laser–matter interaction and high-energy-density plasma experiments. Comparative laser–plasma interaction studies using solid and foam targets were conducted at the Prague Asterix Laser System (PALS) using the first and third harmonics of the laser irradiation. Bremsstrahlung emission was diagnosed using a tunable filter-stack spectrometer designed for sub-nanosecond kilojoule-class iodine laser pulses (λ = 1.315 μm / 0.438 μm, pulse duration ≈ 350 ps, energies up to 600 J and 150 J, respectively). The spectrometer consists of alternating aluminium, copper, tin, and lead filters with imaging plates housed in a lead-shielded enclosure. A 0.3 T magnetic yoke, placed in front of the collimator, suppresses charged-particle interference. Bremsstrahlung spectra were reconstructed by combining Monte Carlo simulations with Bayesian unfolding to derive hot-electron energy distributions and corresponding effective X-ray temperatures. Solid copper targets exhibit higher bremsstrahlung yield and electron temperature than foam targets, indicating reduced fast-electron production and enhanced energy deposition in low-density media. These results are relevant for target optimization in high-energy-density physics and inertial confinement fusion experiments.