Direct measurement of density using Abel transform of Refracted Enhanced Radiograph (RER) in ICF capsule implosion at the National Ignition Facility

X-ray Refraction Enhanced Radiography (RER) experiments have been developed^1,2 recently at the National Ignition Facility to give a direct measurement of density gradients at both fuel-ablator interface and ablation front in indirect drive capsule implosions. While they provided quantitative measurement of mix-width¹ and interface trajectory², the determination of the spatial and time resolved density is done using a forward fit model with high uncertainty. An analytical Abel transform model has been demonstrated³, which allows for the direct deconvolution of the density from the RER data. Thanks to the high signal-to-noise ratio (> 20) and high resolution (< 6 µm) of the most recent dataset, we have been able to, for the first time, apply this model to obtain a direct measurement of the time and spatial variation of the capsule limb density.

[1] E.L. Dewald, O.L. Landen, et al, High En. Dens. Phys. 36, 100795 (2020).

[2] A. Do et al, submitted, Phys. Rev. Lett. (2022).

[3] J. Koch, Applied optics 52 (2013).