A laser beam characterization method is reported, which is applicable to arbitrary and ideal laser beam intensity profiles. This method, called the scattered light imaging method (SLIM), is based on scattered light imaging of a laser beam and provides a complete visualization of it in the region of interest. The method was applied to characterize an arbitrary pedestal-shaped beam and compared with a conventional method (camera scanning). The results we presented show that, for arbitrary beams, it seems much more meaningful to know the intensity profile evolution than to determine an M2 value. Therefore the SLIM is a powerful tool for a new and more complete type of laser beam characterization.

No abstract

No abstract

The observation of current in the afterglow of the discharge in a pulsed hollow-cathode lamp illuminated by tunable lasers, combined with optogalvanic techniques, provides a simple and reliable tool for multi-step photoionization spectroscopy studies. A three-photon photoionization spectroscopy study was performed in a uranium hollow-cathode lamp, using this combination of techniques. Single-, double-and triple-frequency photoionization paths were identified for uranium, in the range between 5900 and 6060 Å.

This work aimed the obtainment of a neutral atomic jet departing from a plume generated by laser ablation of copper targets. A pair of electrodes together with a transducer pressure sensor was used to study the ablated plume charge composition and also to measure the ion extraction from the plasma plume. The neutral beam was produced with this setup and the relative abundance of neutrals in the plasma was measured, it decreases from 30% to 8% when the laser fluence is varied from 20 J/cm(2) to 32 J/cm(2). The necessary voltage to completely remove the ions from the plume varied from 10 V to 230 V in the same fluence range. TOF analysis resulted in center of mass velocities between 3.4 and 4.6 km/s, longitudinal temperature in the range from 1 × 10(4) K to 2.4 × 10(4) K and a Mach number of M = 2.36, calculated using purely hydrodynamic expansion approximation.