A Review of Bigfoot Implosion Data at the National Ignition Facility

We consider the motivations for the high-velocity/high-adiabat approach to indirect drive known as ``Bigfoot,'' and review experiments from 2015 to 2018. We show that performance is a function of symmetry, as expected, and that layered data follows near-1-D scaling(s) for hot-spot pressure\footnote{ K. L. Baker \textit{et al.}, Phys. Rev. Lett. \textbf{121}, 135001 (2018).} and capsule radius.\footnote{ D. T. Casey \textit{et al.}, Phys. Plasmas \textbf{25}, 056308 (2018).} While the design was not intended to achieve high performance, it also reaches high pressure (360 Gbar), yield (2.0~\texttimes ~10$^{\mathrm{16}})$, alpha heating (3.2\texttimes ), and fusion gain $\left[ {1.2\times \sim {\left( Y \right)} \mathord{\left/ {\vphantom {{\left( Y \right)} {\left( {3 \mathord{\left/ {\vphantom {3 {2\;pV}}} \right. \kern-\nulldelimiterspace} {2\;pV}} \right)}}} \right. \kern-\nulldelimiterspace} {\left( {3 \mathord{\left/ {\vphantom {3 {2\;pV}}} \right. \kern-\nulldelimiterspace} {2\;pV}} \right)}} \right],$ at a compression ratio similar to data at a lower-design adiabat (1.5 to 2.5).\footnote{ C. A. Thomas \textit{et al.}, ``Using Indirect Drive Data to Extrapolate in Energy and Scale,'' to be submitted to Physical Review Letters.} We use these results to extrapolate in energy and scale,\footnote{ C. A. Thomas \textit{et al.}, ``Compression in High-Performance Indirect Drive Implosions at the National Ignition Facility,'' to be submitted to Physical Review Letters.} and suggest experiments that could explain current performance (limits). This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE{\-}AC52-07NA27344 and is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856.