In this paper we present one-dimensional numerical simulations of compression and burn of a high-gain indirect drive inertial fusion target suitable for use in a reactor system. The target consists of a capsule that contains 4.45 mg of DT fuel and the capsule is enclosed in a solid gold casing. The inner radius of the casing is twice larger than the outer radius of the capsule so that the inner surface area of the hohlraum wall is four times larger than the capsule surface area. The cavity is filled with a homogeneous radiation field whose intensity increases in time in an appropriate manner reaching a maximum radiation temperature of 300 eV. The capsule is driven to thermonuclear burn by this radiation field. The target (capsule + casing) absorbs an input energy of about 5.6 MJ and the implosion produces an output energy of 720 MJ so that the overall energy gain of this target is of the order of 130.