Optimal design of shock ignition target in order to stop generated hot electrons within the cold fuel

Abstract

Generation of hot electrons (HEs) within ignitor pulse interaction with pre-compressed fuel is an important challenge in the shock ignition approach.Target optimization in order to prevent the destructive effects of HE is the main goal of the present work. In the first stage, the spectrum of electron energy generated during the interaction of ignitor pulse at different widths with the HiPER pre-compressed target has been estimated by applying particle simulation tool. Then, by changing the thickness of the cold fuel in the range of 185-225 μm, the corresponding areal densities are calculated using 1D hydrodynamic simulations. Finally, in order to assess the energy fusion yield, the iso-gain curves are obtained for different ignitor time windows as well as target thicknesses. Simulation results indicate that by decreasing the baseline, target thickness leads to a 17-70% increase in the fuel areal density. Subsequently, it has been demonstrated that by properly adjusting the parameters of ignitor pulse launch time and its width and employing a target with areal density high enough to stop the HEs, energy gain above 140 can be achieved. Optimal areas for shell thickness and ignitor time window are identified.