Suprathermal electron drive and symmetry effects in intermediate density (ρDT2g/cm3) laser-fusion targets

Abstract
The effect of suprathermal electron drive on symmetry and uniformity of compression is studied for directly irradiated, thick-wall laser-fusion targets. In these experiments, in which suprathermal electron range is comparable to target-wall thickness, two-dimensional multispectral x-ray images (2.5, 4.5, 6, and 17 keV) support the conclusion that suprathermal electrons dominate target drive. Although symmetry is improved by the suprathermals, drive nonuniformities persist through the implosion process, compromising the ultimate symmetry and uniformity of compression. These experiments explicitly demonstrate the need to moderate suprathermal electron production and improve drive symmetrization.