Smoothing of laser energy deposition by gas jets

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 mu m with an intensity of about 10(15) W/cm(2). The laser beam has been split in two by a prism thus creating an artificial large-scale non-uniformity (approximate to 90 mu m). 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.