Achievement of Laser Fusion with High Energy Efficiency Using a Mixture of D and T Ions

Abstract

A mixture of deuterium (D) and tritium (T) is the most likely fuel for laser-driven inertial confinement fusion (ICF) reactors and hence DD and DT are the fusion reactions that will fire these reactors in the future. Neutrons produced from the two reactions will escape from the burning plasma, in the reactor core, and they are the only products possible to be measured directly. DT/DD neutron ratio is crucial for evaluation of T/D fuel ratio, burn control, tritium cycle and alpha particle self-heating power. To measure this ratio experimentally, the neutron spectra of DD and DT reactions have to be measured separately and simultaneously under high neutron counting with sufficient statistics (typically within 10% error) in a very short time and these issues are mutually contradicted. That is why it is not plausible to measure this high priority ratio for reactor performance accurately. Precise calculations of the DT/DD neutron ratio are needed. Here, we introduce such calculations using a three dimensional (3-D) Monte Carlo code at energies up to 40 MeV (the predicted maximum ion acceleration energy with the available laser systems). In addition, the fusion power ratio of DD and DT reactions is calculated for the same energy range. The study indicates that for a mixture of 50% deuterium and 50% triton, with taking into account the reactions D(d,n)3He and T(d,n)4He, the optimum energy value for achieving the most efficient laser-driven ICF is 0.08 MeV.