NUKLEONIKA 2011, 56(2):113-117

 


LASER-INDUCED ABLATION: PHYSICS AND DIAGNOSTICS
OF ION EMISSION



Lorenzo Torrisi1,2

1 Laboratori Nazionali del Sud,
Istituto Nazionale di Fisica Nucleare (National Institute for Nuclear Physics),
62 S. Sofia Str., 95123 Catania, Italy
2 Dipartimento di Fisica, Universita di Messina,
Ctr. da Papardo-Sperone 31, 98166 Messina, Italy

Pulsed lasers generating beams of different intensities may be used to produce ablation of solid targets placed in high vacuum and to generate pulsed plasma and ion acceleration. The plasma is in a non-equilibrium condition and in the first instant the particles being generated are subject to thermal interactions, to a supersonic gas expansion in vacuum and to a Coulomb acceleration due to the high electric field developed along the normal to the target surface. The ion diagnostics, based on time-of-flight technique, allow us to measure the mean ion energy, the total number of ions, as well as the ion energy and charge state distributions. The ion energy distributions may be described by the Coulomb-Boltzmann-Shifted (CBS) function, which after fitting to the experimental data may be used to determine the equivalent ion temperature and the accelerating voltage. Given the equivalent acceleration voltage and the plasma Debye length, it is possible to estimate the magnitude of the electric field developed in the plasma. Measurements of the ablation yield, plasma dimension and optical spectroscopy allow us to calculate the atomic and electronic plasma density and to evaluate the coronal plasma temperature. Some applications of the laser-induced ablation consist in the realization of laser ion sources (LIS), generation of multi-energetic ion beams by using a post-accelerating voltage, use of ultra-intense fs lasers to accelerate ions to energies of the order of tens MeV/nucleon. Other special applications include the pulsed laser deposition (PLD) of thin films, the laser ablation coupled to mass quadrupole spectrometry (LAMQS) probes, ablation of biological tissues, and generation of plasma for astrophysical and nuclear investigations.

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