No abstract

A large-scale, double-stream gas puff target has been illuminated by sub-kJ, near-infrared (NIR) focused laser pulses at the PALS facility (Prague Asterix Laser System) to produce high-energy pulses of soft X rays from hot, dense plasma. The double-puff arrangement ensures high gas density and conversion efficiency from NIR to X rays approaching that typical for solid targets. In addition, its major advantage over solid targets is that it is free of debris and has substantially suppressed charged-particle emission. The X-ray emission characteristics of the source were determined for a range of gases that included krypton, xenon, N(2), CO and N(2)-CO. A demonstrated application of the xenon-based source is a single-shot damage induction to plasmid DNA. The yields of single-strand breaks (SSBs) and double-strand breaks (DSBs) were determined as a function of energy fluence adjusted by varying distance of sample from the source and thickness of aluminum filters.

Recently developed three-frame complex-interferometry system driven by a Ti:Sa laser with 40 fs pulse has been installed at the PALS (Prague Asterix Laser System) laser facility. This unique diagnostic allows for the first time to perform simultaneous measurements of B-field in the coil region of the capacitor-coil targets (CCT) and the self-generated B-field (SMF) of the diode plasma in between the CCT-plates. CCT were irradiated by the PALS iodine laser (λ = 1315 nm) with energy in the range 250–500 J and pulse duration of 350 ps at full width at half maximum. The operation of this diagnostic system and methodologies for quantitative data analysis are presented in this study, including: (i) obtaining information about the induction of the magnetic field in the CCT coil based on measurements of the Faraday effect in the TGG (Terbium Gallium Garnet) paramagnetic crystal at the coil vicinity and (ii) determining magnetic field and current density distributions in the capacitor region of the CCT by analysis of the complex interferograms. The preliminary measurements confirmed the high potential of the reported setup for optimization studies of CCT targets.

The aim of the reported research is to contribute to investigation of new processes and methods interlinking nuclear and laser-plasma physics. With respect to requirements of nuclear experiments at medium-size high-power lasers, the selection of proper candidates for studying the excitation and decay of low-lying nuclear states is reviewed. An experimental approach to the identification of low-energy nuclear transitions is discussed, simple estimates of the 181 Ta excitation yield in the laser-generated plasma provide a theoretical basis for planning future work. First tests and results of the experiments at the laser facility PALS are presented.