Effect of plastic coating on the density of plasma formed in Si foil targets irradiated by ultra-high-contrast relativistic laser pulses

The formation of high energy density matter occurs in inertial confinement fusion, astrophysical, and geophysical systems. In this context, it is important to couple as much energy as possible into a target while maintaining high density. A recent experimental campaign, using buried layer (or "sandwich" type) targets and the ultrahigh laser contrast Vulcan petawatt laser facility, resulted in 500 Mbar pressures in solid density plasmas (which corresponds to about 4.6×107J/cm3 energy density). The densities and temperatures of the generated plasma were measured based on the analysis of X-ray spectral line profiles and relative intensities

Features of the generation of fast particles from microstructured targets irradiated by high intensity, picosecond laser pulses

The use of targets with surface structures for laser-driven particle acceleration has potential to significantly boost the particle and radiation energies because of enhanced laser absorption. We investigate, via experiment and particle-in-cell simulations, the impact of micron-scale surface-structured targets on the spectrum of electrons and protons accelerated by a picosecond laser pulse at relativistic intensity. Our results show that, compared with flat-surfaced targets, structures on this scale give rise to a significant enhancement in particle and radiation emission over a wide range of laser-target interaction parameters. This is due to the longer plasma scale length when using micro-structures on the target front surface. We do not observe an increase in the proton cutoff energy with our microstructured targets, and this is due to the large volume of the relief

X-ray absorption spectroscopy study of energy transport in foil targets heated by PW laser pulses

Absorption x-ray spectroscopy is proposed as a method for studying the heating of a solid-density matter excited by secondary xray radiation from a relativistic laser-produced plasma. The method was developed and applied to experiments involving thin silicon foils irradiated by 0.5–1.5 ps duration ultrahigh contrast laser pulses at intensities between 0.5×1020 and 2.5×1020 W/cm2 . The electron temperature of the material at the rear side of a target is estimated to be in the range of 140–300 eV. The diagnostic approach enables the diagnosis of warm dense matter states with low self-emissivity

In-depth study of intra-Stark spectroscopy in the x-ray range in relativistic laser-plasma interactions

Intra-Stark spectroscopy (ISS) is the spectroscopy within the quasistatic Stark profile of a spectral line. The present paper advances the ISS-based study of the relativistic laser-plasma interaction from our previous paper (Oks et al 2017 Opt. Express 25 1958). By improving the experimental conditions and the diagnostics, it provides an in-depth spectroscopic study of the simultaneous production of the Langmuir waves and of the ion acoustic turbulence at the surface of the relativistic critical density. It demonstrates a reliable reproducibility of the Langmuir-wave-induced dips at the same locations in the experimental profiles of Si XIV Ly-beta line, as well as of the deduced parameters (fields) of the Langmuir waves and ion acoustic turbulence in several individual 1 ps laser pulses and of the peak irradiances of 1-3 ×1020 W cm-2. Besides, this study employs for the first time the most rigorous condition of the dynamic resonance, on which the ISS phenomenon is based, compared to all previous studies in all kinds of plasmas in a wide range of electron densities. It shows how different interplays between the Langmuir wave field and the field of the ion acoustic turbulence lead to distinct spectral line profiles, including the disappearance of the Langmuir-wave-induced dips

Characterization of a new Leishmania major strain for use in a controlled human infection model

Controlled human infection models (CHIMs) provide a pathway for accelerating vaccine development. Here, the authors describe the isolation, characterization, and GMP manufacture of a clinical Leishmania major strain to be used as a resource for CHIM studies of sand fly transmitted cutaneous leishmaniasis

Determining the short laser pulse contrast based on X-Ray emission spectroscopy

The interaction of high-power short lasers with solid density targets is an important application of modern solid state lasers. However, uncertainties in measurements due to lack of information on the laser pedestal-to-peak contrast limits the validity of many conclusions. We show that X-ray spectral measurements can provide a straightforward way for accessing the laser pedestal-to-peak contrast. The experiments use silicon targets and relativistic laser intensities of 3 × 1020 W/cm2 with a pulse duration of 1 ps. By not using or using a plasma mirror we compare low and high contrast measurements of the Ly-α line and its satellites to show that these lines are an effective laser contrast diagnostic. This diagnostic has potential to reduce uncertainty in future laser-solid interaction studies