Characterization of particles generated by laser–plasma interaction in ICF-related conditions

We report an experimental characterization of proton and electron beams generated by laser-plasma interaction under ICF-like conditions. The generation, heating and transport of hot electrons were studied at shock ignition intensities (I > 1016 W/cm2) at the PALS laser system (Czech Republic) using several complementary diagnostics, i.e. Kα-time-resolved imaging, hard X-ray filtering (a bremsstrahlung cannon) and electron spectroscopy. Ablators with different compositions were used in multilayer planar targets to produce plasmas with different coronal temperatures and collisionality and modify the conditions for hot electron generation. The variety of available diagnostics enabled a complete characterization of the population of hot electrons, retrieving their conversion efficiency, time of generation and duration, temperature and angular divergence. Based on the measured data, the advantages, reliability and complementarity of the experimental diagnostics are discussed.

Experimental characterization of proton beams was performed with ultrashort PW laser pulses in CLPU (VEGA-3, Spain), which are required for Fast Ignition or HB-related concepts. We present a versatile high-repetition-rate solid tape target system suitable for relativistic laser plasma-driven secondary sources. The maximum proton energy measured with Thomson Parabola and time-of-flight diagnostics shows a significant decrease at the maximum pulse compression. The origin of this behavior is investigated and complemented by numerical simulations and compared with the trends predicted by previous theoretical models.