Experimental results and theoretical analysis of the effect of wavelength on absorption and hot-electron generation in laser-plasma interaction

Recent experiments performed at École Polytechnique on the wavelength scaling of laser light absorption by flat plastic targets are presented and interpreted. The measurements show larger absorption fractions for shorter laser wavelengths, lower laser intensities, and longer laser pulse lengths. These experiments are analyzed using computer hydrodynamics codes, and show that there are two possible physics models consistent with the data: (1) Inhibited electron heat flow together with absorption rates higher than those predicted by resonance absorption and inverse bremsstrahlung. (2) Nearly classical heat flow, with no additional enhancement in the absorption rate.