Burn performance of fast ignited, tritium-poor ICF fuels

Abstract

The potentials of fuels that are predominantly deuterium, with a small tritium content (tritium-poor deuterium), are examined in the context of the inertial confinement fusion (ICF) scheme known as `fast ignitor', which is based on external heating of a portion of a precompressed target. For this purpose, the burn performance of compressed spheres of pure or nearly pure deuterium with an off-centre deuterium-tritium (DT) seed, ignited by an ultrapowerful external beam, has been studied using two dimensional (2-D) numerical simulations. The dependences of the fuel energy gain on the fuel mass and energy, and on the tritium fractional content FT, have been studied; limiting gain curves have been obtained for fixed values of FT and of the isentrope parameter alpha . It is found that assemblies with FT=0.5-1%, fuel mass m approximately=20 mg, compressed at density rho approximately=1000 g/cm3, can achieve tritium self-sufficiency (i.e. net tritium production). At alpha approximately=1.5, the corresponding fuel energy at ignition is of the order of 1 MJ and the fuel energy gain can be about 1000. The potentials of tritium-poor configurations are also compared with those of equimolar DT fuels with different ignition configurations