Interaction and Transport Processes Illustrated by Measurement of the Electron-Density Profile of a Laser-Irradiated Microsphere

The electron-density profile in the corona of 40-μm-diam glass spheres irradiated by 100-GW, 50-ps pulses from a Nd-glass laser was measured. Critical density scale lengths of 1.5 μm have been observed at rather low intensity (3×${10}^{14}$ ${\mathrm{W}/\mathrm{c}\mathrm{m}}^2$). At high irradiance (${10}^{15}$ ${\mathrm{W}/\mathrm{c}\mathrm{m}}^2$) variation of density is sufficient to blur the interferograms. This observation is correlated with an increase of fast-ion emission.