Features of lateral energy transport in CO2-laser-irradiated microdisk targets

Calorimetric investigations of the lateral flow of energy away from C${\mathrm{O}}_2$-laser-irradiated regions of disk targets are reported. The fraction of energy reaching the rear surface is shown to decrease with increasing target diameter, but does not depend on target thickness. Most of the plasma blow-off energy in front of the target is due to fast ions, but these account for less than 20% of the rear blow-off energy. The rear surface is heated preferentially at the edges, in the plane of laser polarization. These observations are consistent with energy being transported laterally by hot electrons inside the corona which expands at a speed of ∼ ${10}^8$ cm/s.