Modeling of ICF Implosions With an Applied Magnetic Field
Robert Spiers, University of Delaware
An approach to increase the fusion yield and robustness of conventional inertial confinement fusion (ICF) is to apply an axial magnetic field (10 T – 50 T) to the implosion. In this method, the magnetic fields compress to 1000s of Tesla with the converging implosion, magnetizing the central hot spot which suppresses thermal conduction losses and improves confinement of alpha particles. Recent NIF experiments with a 12 T and 26 T applied field show a 40% increase in ion temperature, 3.1x increase in neutron yield [1,2] and suggest that the hot spot temperature profile changes for magnetized experiments with respect to the unmagnetized reference experiments [3]. We present an analytic magnetized hot spot model to determine the radial temperature profile of magnetized experiments. Instead of temperature being nearly uniform throughout the hot spot, we find that magnetized implosions have concentrated high temperature near the center. This model accurately explains the observed temperature profiles in the NIF experiments. However, the scaling of the neutron yield with magnetization is in large discrepancy between simulations, experiments and theory. We discuss this difference by analyzing the experiment data and conducting new high-resolution simulations including yield degradation from high-Z ablator mix. These models close the gap between simulations and experiments to support the magnetized ICF campaign at the NIF.