Simulated Gamma-Ray Images of NIF Capsule Implosions

Gamma-ray imaging of burning inertial confinement fusion capsules give information on where the ablator is during the final stages of the implosion. The ablator areal density (rhoR) can be inferred through gamma-ray detection if the capsule’s total neutron yield is measured [1]. Capsule implosions on the National Ignition Facility (NIF) have recently achieved ignition [2] with repeat experiments achieving much lower yields than expected. Degradation mechanisms are a leading theory as to why there is such variability in the repeats. Recent simulation work has shown that capsule defects lead to collections of jets in the shell that reduce overall compression of the DT fuel [3-4]. We present high resolution 2D simulations using radiation-hydrodynamics code xRAGE [5] of NIF shots N211024 and N211107 using clean/degraded capsules. We compare simulated rhoR and gamma-ray images with experiments.

References

[1] N.M. Hoffman et al, Rev. Sci. Instrum., 81, 10D332 (2010)

[2] H. Abu-Shawareb et al, PRL, 129, 075001 (2022)

[3] B. M. Haines et al, Phys. Plasmas, 29, 042704 (2022)

[4] B. M. Haines et al, Phys. Plasmas, 26, 012707 (2019)

[5] M. L. Gittings et al, Comput. Sci. Discov., 1, 015005 (2008)