Scattering of incident KrF laser radiation resulting from the laser-induced breakdown of H_2O droplets

The time history of elastically scattered incident radiation (ESIR) is presented for 60-microm-diameter water droplets irradiated by KrF (lambda = 248 nm) laser pulses with power densities in the range of 1-200 GW/cm(2). The ESIR shows a distinct two-peak structure that is dependent on the incident irradiance. The time delay between the arrival of the incident pulse and the first local minimum in the ESIR varied from 7 nsec at 200 GW/cm(2) to 21 nsec at 5 GW/cm(2). The time between incident pulse arrival and the first peak in the ESIR showed a similar irradiance dependence, with delays ranging from 4 to 12 nsec. Images of droplet breakup and the average velocities of ejected material are presented for times between 0 and 1000 nsec after the arrival of 3-GW/cm(2) laser pulses.