Imploding indirect-drive double shell targets may provide an
alternative, non-cryogenic path to ignition at the National Ignition
Facility (NIF). Experiments are being pursued at OMEGA to understand the
hydrodynamics of these implosions and the possibility of scaling it to the
NIF design. We have used 40 beams from the OMEGA laser to directly drive
the capsules, and we have used the remaining 20 beams to backlight the
imploding shells from two different directions at multiple times. We will
review the recent experiments to measure the hydrodynamics of the targets
using two-view X-ray radiography of the capsules. We will present data on
measured yields from the targets. We will present a measured time history
of the hydrodynamics of the implosion. Experiments were pursued using
direct drive in which the M-band effect (experienced in the indirect drive
experiments) could be eliminated or controlled. It was learned in the
direct drive experiments that the best performing capsules were those that
had a thin outer layer of gold. This effectively causes M-band pre-heat
effects giving implosion hydrodynamics and performance closer to the
indirect drive case. We will review the methods used to radiograph the
targets and the techniques used to extract useful information to compare
with calculations. The effect of imperfections in the target construction
will be shown to be minimal during the initial stage of implosion. The
yields from the targets were observed to be uniformly low compared to
indirect-drive.