<i>K</i> _α -radiation from relativistic laser-produced plasmas

Abstract

We present systematic investigations on the generation of titanium Kα-radiation (E = 4.5 keV) from plasmas produced with ultrashort, high-intensity laser pulses. A maximum Kα-yield appears at a laser intensity of about 3·1017W/cm2, corresponding to a plasma electron temperature of a few times the Kα photon energy. We observe a second increase in the Kα-emission yield at intensities higher than a few times 1018W/cm2, due to the increase in the K-shell ionization cross-section for relativistic electrons. The intensity dependence of the Kα-yield is modeled by an analytical expression, only including cross-section, pathlength and electron energy distribution.