Modeling of a tomography-based time-resolved neutron imager for inertial confinement fusion*

Neutron imaging is a core diagnostic for inertial confinement fusion (ICF) experiments at the National Ignition Facility (NIF). This capability enables visualization of the burning hotspot, given that each DT fusion event releases a characteristic 14.1 MeV neutron. Current neutron imaging systems are restricted to a single neutron energy range per camera, which can be configured to >14 MeV (reaction-in-flight neutrons), ~14 MeV (primary neutrons), or <14 MeV (down-scattered neutrons). However, ongoing demonstration of ignition on the NIF might soon enable previous concepts [1] for energy-resolved neutron imaging. One design is based on the 1D ion temperature imaging [2] and multiplexed time-of-flight [3] techniques explored on OMEGA. This design would utilize layered scintillator grids along the same line-of-sight to reconstruct a quasi-2D neutron image as a function of energy using time-of-flight. Such a measurement could enable exploration of spatially resolved ion temperature, hotspot rotation, and more. Current progress on forward modeling based on experimental data will be presented and future steps will be outlined.

[1] G. Grim, et al., RSI 79, 10E537 (2008).

[2] C. Danly, et al., RSI 94, 043502 (2023).

[3] L. Tafoya, et al., Submitted to RSI, (2024).