The requirements of matching shell ICF target parameters, parameters
of compressing, and triggering drivers under direct (fast) ignition are
developed. Thin shell target, which represents a shell-ablator with a
DT-ice layer, frosted on the inner surface of the shell are considered.
Design of a target which ensures the energy supply from the triggering
driver to the central part of thermonuclear fuel, in both spherical and
cylindrical geometry is developed. Spherical target is furnished with one
or two conical channels for the injection of the triggering driver
radiation. The ends of the cylindrical target are protected by heavy
material walls that have the holes of the radius equal to the final radius
of compressed fuel. It was found that the parameters of fast ignition
spherical and cylindrical targets, which provide high thermonuclear gain
of 500–2000 in the range of the compressing driver energy of
1–10 MJ, may be matched with the drivers parameters at low aspect
ratios of the targets, 10–20. The operation of spherical targets at
the moderate radius convergence ratio of 15–20, may be provided at
the triggering driver energy not higher than 30 kJ. The operation of
cylindrical target with spin-oriented DT-fuel at radius convergence ratio
of 20–25 may be provided at 150–200 kJ of the triggering
driver energy.