arXiv subjects

B. A. Hammel

Publications and source records attributed to B. A. Hammel.

4 recordsLinked to original sources

arXiv2026

Indirect-Drive Fusion Target Design for Commercial Fusion Energy

This paper presents the physics basis for commercially relevant laser indirect-drive (LID) (radiation-driven) inertial fusion energy (IFE) using a 10 MJ laser driver. To date, this approach, proven at the National Ignition Facility (NIF), remains the first and only controlled fusion method to demonstrate the key physics required for fusion energy production, including a self-sustained burning plasma, substantially de-risking the path to commercial fusion energy. Building directly on these results, we present scaled designs to larger target sizes and fusion gains relevant for commercial power generation ($G\sim 26$--$43$). The designs remain close to experimentally demonstrated ignition physics, modifying target components to improve scalability, manufacturability, and cost-effectiveness for fusion energy applications while preserving ignition-relevant implosion physics and fusion power plant compatibility. The baseline platform retains a high-density carbon ablator and clean cryogenic DT fuel layering while extending ignition platforms to substantially larger fuel masses (exceeding 10 times that of current ignition experiments at the NIF) and higher burn fractions ($\sim$40\%) with total areal densities at stagnation of $\sim$3~g/cm$^2$. Benchmarked simulations anchored to NIF ignition experiments (using HYDRA and LASNEX) predict that these designs achieve robust ignition and propagating burn at substantially higher fusion yields (265--427~MJ) with significant ignition margin (2--4$\times$ relative to NIF) against hydrodynamic instabilities and representative power-plant non-idealities, including low-mode asymmetry, polycrystalline DT ice roughness, HDC ablator voids, and target-support and fill-hole perturbations. We also show that implosion symmetry and laser-plasma interactions (LPI) can be controlled with our novel multi-beam configuration using thousands of laser beam-lines.

physics.plasm-ph↗

arXiv2026

Spherical compression of an applied magnetic field in inertial confinement fusion

Applying an external magnetic field to laser-driven inertial confinement fusion implosions is a promising approach for enhancing fusion yield. The field is compressed with the plasma, producing a magnetized hotspot that anisotropically suppresses thermal losses and traps alpha particles, making performance sensitive to the compressed field orientation. We derive a simple, readily applicable analytic model that enables rapid evaluation of the compressed field topology and show that ablation into the hotspot amplifies the central field, while the ablated ice near the hotspot edge develops a decaying, radially bent field, with a discontinuity in the field direction. The radially bent field renders thermal insulation at the hotspot edge negligible and largely independent of the applied field strength, whereas insulation in the hotspot core still depends strongly on the applied field. Applying the model to non-axial initial field configurations, we find that an initially applied mirror field provides the greatest suppression, followed by the standard axial field.

physics.plasm-ph↗

arXiv2024

Design and Modeling of Indirectly-Driven Magnetized Implosions on the NIF

The use of magnetic fields to improve the performance of hohlraum-driven implosions on the National Ignition Facility (NIF) is discussed. The focus is on magnetically insulated inertial confinement fusion (ICF), where the primary field effect is to reduce electron-thermal and alpha-particle loss from the compressed hotspot (magnetic pressure is of secondary importance). We summarize the requirements to achieve this state. The design of recent NIF magnetized hohlraum experiments is presented. These are close to earlier shots in the three-shock, high-adiabat (BigFoot) campaign, subject to the constraints that magnetized NIF targets must be fielded at room-temperature, and use < 1 MJ of laser energy to avoid risk of optics damage from stimulated Brillouin scattering. We present results from the original magnetized hohlraum platform, as well as a later variant which gives higher hotspot temperature. In both platforms, imposed fields (at the capsule center) of up to 28 T increase the fusion yield and hotspot temperature. Integrated radiation-magneto-hydrodynamic (rad-MHD) modeling with the Lasnex code of these shots is shown, where laser power multipliers and a saturation clamp on cross-beam energy transfer (CBET) are developed to match the time of peak capsule emission and the P2 Legendre moment of the hotspot x-ray image. The resulting fusion yield and ion temperature agree decently with the measured relative effects of the field, although the absolute simulated yields are higher than the data by 2.0-2.7X. The tuned parameters and yield discrepancy are comparable for experiments with and without an imposed field, indicating the model adequately captures the field effects. Self-generated and imposed fields are added sequentially to simulations of one BigFoot NIF shot to understand how they alter target dynamics.

physics.plasm-ph↗

arXiv2021

Experiments conducted in the burning plasma regime with inertial fusion implosions

An experimental program is currently underway at the National Ignition Facility (NIF) to compress deuterium and tritium (DT) fuel to densities and temperatures sufficient to achieve fusion and energy gain. The primary approach being investigated is indirect drive inertial confinement fusion (ICF), where a high-Z radiation cavity (a hohlraum) is heated by lasers, converting the incident energy into x-ray radiation which in turn drives the DT fuel filled capsule causing it to implode. Previous experiments reported DT fuel gain exceeding unity [O.A. Hurricane et al., Nature 506, 343 (2014)] and then exceeding the kinetic energy of the imploding fuel [S. Le Pape et al., Phys. Rev. Lett. 120, 245003 (2018)]. We report on recent experiments that have achieved record fusion neutron yields on NIF, greater than 100 kJ with momentary fusion powers exceeding 1PW, and have for the first time entered the burning plasma regime where fusion alpha-heating of the fuel exceeds the energy delivered to the fuel via compression. This was accomplished by increasing the size of the high-density carbon (HDC) capsule, increasing energy coupling, while controlling symmetry and implosion design parameters. Two tactics were successful in controlling the radiation flux symmetry and therefore the implosion symmetry: transferring energy between laser cones via plasma waves, and changing the shape of the hohlraum. In conducting these experiments, we controlled for known sources of degradation. Herein we show how these experiments were performed to produce record performance, and demonstrate the data fidelity leading us to conclude that these shots have entered the burning plasma regime.

physics.plasm-ph↗