Application of Non-Uniform Magnetic Fields to Inertial Confinement Fusion Implosions

Uniform axial magnetic fields up to 26T have been applied to inertial confinement fusion implosions on the National Ignition Facility, achieving temperature and neutron yield enhancements of 40% and 3.2x respectively [1]. These are roughly in-line with theoretical predictions from suppression of heat-flow in 2 of the 3 spatial dimensions [2]. Experiments, simulations and theory all agree that the performance enhancement due to magnetization for this platform has approximately plateaued by 26T.

This talk investigates (using the extended-magnetohydrodynamics code Gorgon [3,4]) benefits of applying non-uniform magnetic fields. For example, a magnetic mirror field is found to enhance the maximum performance improvement; this is due to the hot-spot having a greater surface area where the heat-flow is suppressed. A cusp magnetic field, which can be achieved by reversing the coil turn axis on different ends of the hohlraum, is also investigated. The application of closed magnetic field lines is found to have the greatest impact on the hot-spot electron temperature, although it is still unclear how such a magnetic field topology would be applied experimentally.

 

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.