LASER induced breakdown spectroscopy (LIBS) has been used for the quantitative analysis of Cu–Ni alloy of known composition (75% Cu, 25% Ni) using the one line calibration free-LIBS (OLCF-LIBS), self-calibration-LIBS (SC-LIBS), calibration free LIBS (CF-LIBS), time of flight-mass spectroscopy (TOF-MS), energy dispersive X-ray spectroscopy (EDX) and X-ray fluorescence spectroscopy (XRF). For the LIBS-based studies, the plasma was generated by focusing the beam of a Q-switched Nd:YAG laser (532 nm, pulse energy about 200 mJ, 5 ns pulse duration) while the sample was placed in air at an atmospheric pressure. Plasma temperature about (9500 ± 300) K was calculated by the Boltzmann plot method using the neutral lines of Cu and Ni whereas the electron number density was calculated (2.0 ± 0.5) × 1016 cm−3 from the Stark broadening of an isolated Cu line as well as using the relative intensities of the neutral and singly ionized optically thin lines in the Saha–Boltzmann equation. The elemental compositions determined by different LIBS methods and standard techniques are; OLCF-LIBS (69% Cu and 31% Ni), SC-LIBS (72% Cu and 28% Ni), CF-LIBS (74% Cu and 26% Ni), TOF (74% Cu and 26% Ni), EDX (75% Cu and 24.5% Ni), XRF (73% Cu and 24.7% Ni), and LA-TOF (74% Cu and 26% Ni). It is demonstrated that the CF-LIBS method gives compositions comparable with that determined by LA-TOF, EDX, or XRF, which is also in agreement with the certified reported composition.

This paper aims at investigation of efficiency of an ablative plasma energy transfer into a massive aluminum target using different atomic number ablators. For this reason, several target materials representing a wide range of atomic numbers (Z = 3.5–73) were used. The experiment was carried out at the iodine Prague Asterix Laser System. The laser provided a 250 ps pulse with energy of 130 J at the third harmonic frequency (λ3 = 0.438 μm). To study the plasma stream configurations a four-frame X-ray pinhole camera was used. The electron temperature of the plasma in the near-surface target region was measured by means of an X-ray spectroscopy. The efficiency of the plasma energy transport to the target was determined via the crater volume measurement using the crater replica technique. The experimental results were compared with two-dimensional numerical simulations where the plasma dynamics was based on the one-fluid, two temperature model, including radiation transport in diffusive approximation and ionization kinetics. It was shown that the plasma expansion geometry plays an important role in the ablative plasma energy transfer into the target.

In this work, we present the spectroscopic studies of the plasma generated at the surface of manganese sulfate by the fundamental (1064 nm) and second harmonic (532 nm) of a Q-switched Nd:YAG laser. The 4s4p 4F7/2→ 4s 2H9/2 at 438.80 nm, 4p 2I11/2 → 4s22I11/2 at 440.80 nm, 4p 4G11/2 → 4s 2H9/2 at 464.27 nm, 4p 4F5/2→ 4s 4D7/2 at 467.16, 4p 4F5/2 → 4s24G 7/2 at 515.08 nm, and 4p 4F7/2 → 4s2 4G 9/2 at 519.65 nm transitions have been used to estimate the electron temperature through the Boltzmann plot method. The number density has been estimated from the Stark broadened profiles of the spectral line 348.30 nm. The spatial behavior of the electron temperature and number density has been examined at different ambient air pressures and with laser irradiance. The temperature and number density are found to be in the range from 9842 K to 9371 K and 1.58 × 1017 to 3.26 × 1016 cm−3 for the 1064 nm laser, from 9668 to 9297 K and 2.27 × 1017 to 5.79 × 1016 cm−3 for the 532 nm laser.

The paper is directed to the study of high-temperature plasma and ablation plasma formation as well as efficiency of the laser energy transfer to solid targets irradiated by laser pulses with intensities of 1–50 PW/cm2 and duration of 200–300 ps, i.e., at conditions corresponding to the characteristics of the laser spike designed to generate the igniting shock wave in the shock ignition concept. The experiments have been performed at Prague Asterix Laser System. The iodine laser delivered 250 ps (full width at half maximum) pulses with the energy in the range of 100–600 J at the first (λ1 = 1.315 µm) and third (λ3 = 0.438 µm) harmonic frequencies. The focal spot radius of the laser beam on the surface of Al or Cu targets made was gradually decreased from 160 to 40 µm. The diagnostic data collected using three-frame interferometry, X-ray spectroscopy, and crater replica technique were interpreted by two-dimensional numerical and analytical modeling which included generation and transport of fast electrons. The coupling parameter Iλ2 was varied in the range of 1 × 1014−8 × 1016 Wμm2/cm2 covering the regimes of weak to intense fast electron generation. The dominant contribution of fast electron energy transfer into the ablation process and shock wave generation was found when using the first harmonic laser radiation, the focal spot radius of 40–100 µm, and the laser energy of 300–600 J.

Self-focusing effects, induced by ASTERIX pulsed laser at PALS Laboratory of Prague, have been investigated. Laser was employed at the third harmonics (438 nm) and intensities of the order of 1016 W/cm2. Pure Au was used as thin target and irradiated with 30° incidence angle. An ion energy analyzer was employed to detect the energy-to-mass ratio of emitted ions from plasma. Measurements were performed by changing the focal point position with a high spatial resolution step-motor. Results demonstrated that non linear processes, due to self-focusing effects, occurs when the laser beam is focused at about 200 µm in front of the target surface. In such conditions, a new ion group, having high charge state and kinetic energy, is produced because of the increment in temperature of the laser-generated plasma.

Saturation effects in laser-induced breakdown spectroscopy in water for elemental analysis have been investigated. Existing theoretical model of laser-induced plasma in solids has been applied to liquid phase under some simplifying assumptions to take account of the laser pulse energy dependence of atomic emissions from Na and Cu in aqueous solution. The theory was found to explain the emission process for laser energies up to but below the saturation level. The saturation limit of the emission with laser pulse energy corresponds well with that of the plasma temperature deduced from blackbody emission considerations. The saturation energies for atomic emissions were found to be lower for bulk excitations compared to water jet excitations. The dependence of signal strength on sample concentration indicated that the concentration values at saturation are lower at higher laser energies, as is expected from the theoretical model.