Eur. Phys. J. Special Topics 175, 65-70 (2009)
DOI: 10.1140/epjst/e2009-01119-2

Smoothing of laser energy deposition by gas jets

D. Batani¹, R. Benocci¹, R. Dezulian¹, R. Redaelli¹, F. Canova¹, H. Stabile¹, G. Lucchini¹, V. Malka², J. Faure², M. Koenig³, E. Krousky⁴, K. Masek⁴, M. Pfeifer⁴, J. Skala⁴, R. Dudzak⁴, J. Limpouch⁵, V. Tikhoncuk⁶ and P. Nicolai<sup>6

1</sup>  Dipartimento di Fisica ''G. Occhialini'', Università di Milano Bicocca, Piazza della Scienza 3, 20126 Milano, Italy
²  LOA, CNRS, ENSTA, École Polytechnique, 91761 Palaiseau, France
³  LULI, École Polytechnique, CNRS, 91128 Palaiseau, France
⁴  PALS Research Centre, Za Slovankou 3, 18221 Prague 8, Czech Republic
⁵  Czech Technical University, Prague, Czech Republic
⁶  Centre Lasers Intenses et Applications, Université Bordeaux 1, 33405 Talence, France

Abstract
Smoothing of laser beam non-uniformities using gas jets has been studied. The experiment has been performed with the PALS laser working at 0.44 μm with an intensity of about 10¹⁵ W/cm². The laser beam has been split in two by a prism thus creating an artificial large-scale non-uniformity (≈90 μm). We recorded time resolved and static images of laser-gas jet interaction with and without an Al target. Multi 1D and 2D simulations show that such interaction acts redistributing the over-intensities over larger surface. This effect has to be attributed to ionization processes with consequent laser beam refraction. Results show that Argon gas jet produces a strong refraction of the laser beam thus strongly reducing the initial two spots separation.

© EDP Sciences, Springer-Verlag 2009