Recently much attention has been paid to multilayer
inertial confinement fusion (ICF) targets, among them the
targets with low-density layers. This allows one to get
a number of interesting results using the presently existing
and future facilities. This concerns the volume absorption
of the laser radiation in a porous matter of the density
higher than the critical plasma density, and the formation
of the radiation absorption region under condition of increasing
geometric opacity of the low-density matter. We consider
the low-density foams, 3D nets, free-standing “snow-like”
layers, and pseudo low-density layers. We use artificial
foam as a convenient model to allow easier comparison of
the experimental laser shot data and the simulation. The
requirements to such layers are also analyzed. The methods
of precision control of the low-density targets are discussed.