PALS laser energy transfer into solid targets and its dependence on the lens focal point position with respect to the target surface

Abstract

This paper is devoted to investigations of laser energy transfer into solid targets with respect to the focusing lens focal point position relative to the solid target surface as obtained at the PALS laser facility. The third harmonic of the PALS laser beam with energy~90 J and pulse duration~250 ps (FWHM) was used for irradiation of two kinds of targets made of Cu: a slab and a 3.6 mm thick foil. The focal point of the beam was located either inside or in front of the target surface, and care was taken to ensure the same laser spot radii in both cases (250 mm). It was demonstrated that these two opposite focal point positions give rise to significantly different laser-plasma interactions: with either depression or maximum of the laser intensity distribution in the center of the beam, respectively. It was also verified that the focal point position inside of the target is favorable for plasma jets creation, whereas the opposite case is more effective for acceleration of flyers.

Interaction between parallel Gaussian electromagnetic beams in a plasma with weakly relativistic-ponderomotive regime

“…Relativistic laser-plasma-interaction physics has also been focus of attention as many nonlinear processes playing key role in the generation of new ion sources as reported recently [34,35]. Further, there have been a series of novel experiments to study rich physics issues in nuclear and particle physics, atomic physics [36], plasma physics [37,38] and applied sciences [39,40].…”

Relativistic and ponderomotive effects on evolution of dark hollow Gaussian electromagnetic beams in a plasma

“…Relativistic laserplasma interaction physics has also been focus of attention as many nonlinear processes playing key roles in the generation of new ion sources as reported recently (Laska et al, 2007;Strangio et al, 2007;Torrisi et al, 2008). Further, there have been a series of novel experiments to study rich physics issues in nuclear and particle physics, atomic physics (Stoehlker et al, 2003), plasma physics Schaumann et al, 2005) and applied sciences (Kuehl et al, 2007;Kasperczuk et al, 2008). Such experiments have opened new vistas in this field and are supposed to pay rich dividents to multidisciplinary character of laser produced plasma.…”

Third harmonic order imaging as a focal spot diagnostic for high intensity laser-solid interactions

“…This is especially important for high intensity interactions, i.e., fast ignition fusion, laser based ion acceleration etc., where fluctuations in intensity can substantially effect the interpretation of entire data sets. Such a monitor is also important for near solid density interactions (plasma density scale length ,l laser , the laser wavelength) that require plasma mirrors, or modified plasma density scale lengths (Dromey et al, 2006(Dromey et al, , 2007Kasperczuk et al, 2008;Laska et al, 2007;Quere et al, 2006). Used to increase the laser contrast ratio (CR, the ratio of peak intensity to that at a few picoseconds before the peak), the operating conditions for the plasma mirror (namely incident intensity) determine the focusability of the reflected light (Dromey et al, 2004;Levy et al, 2007).…”