Progress on magnetized indirect-drive implosions at the National Ignition Facility

Magnetized fuel offers a potentially transformational way to boost the yield of current indirect-drive implosion designs on NIF by a factor of 2 or more and opens the door to new designs specifically tailored for use with a B-field. The NIF program at LLNL has an ongoing project to install the infrastructure needed to test the performance improvement of magnetizing the DT fuel in cryo-layered indirect-drive implosions, and plans to start magnetized layered implosions soon. The first set of magnetized NIF implosions completed during 2021 tested the performance improvement in a room-temperature D₂-filled HDC capsule in a 5.4-mm-diameter AuTa₄ (high-electrical-resistance) hohlraum. The measurements showed that applying a 26-T axial B-field boosted the hot-spot temperature by 40\% from 2.7 keV to 3.8 keV and amplified the DD yield by a factor of 3.2×. The secondary DT yield is used with a static Monte-Carlo model to estimate the compressed B-field in the hot spot. At sufficiently high B-field, the 1.0-MeV tritons from the D(d,p)T reaction can be magnetically confined in the hot spot, increasing their energy loss and probability to undergo a secondary DT fusion reaction (increasing the secondary yield ratio Y_DT/Y_DD). Within the assumptions made by our model, the burn-averaged B-field in the hot spot is estimated to be 4.7 ± 1.3 kT, in good agreement with the LASNEX-simulated B-field at stagnation. We will also summarize current NIF and Omega experiments that are investigating high-energy-density-physics issues relevant to magnetized ignition.