Absorption in high-z targets illuminated with 527-nm laser light at high intensity using induced spatial incoherence.

ABSTRACT

We have measured 527-nm absorption for induced spatial incoherence (ISI) and non-ISI illumination of high-Z targets over the 0.5-3.5 x 10(14)-W/cm(2) laser intensity range using energy balance with a custom designed 30-cm diam light integrating sphere. Induced spatial incoherence of the laser beam was produced by inserting echelons in the beam path and operating the laser at wide bandwidth (0.2%). To produce ISI and non-ISI data for comparison, we irradiated a large number of 180-microm diam gold disks with 0.5-1.5-ns pulses with echelons in the beam path with and without wide laser bandwidths. Our data show an increase in absorption of 5-11% for the ISI illuminated targets and also suggest a weaker dependence of absorption on laser intensity for ISI illumination than for non-ISI.