Analysis of trends in experimental observables and reconstruction of the implosion dynamics for direct-drive cryogenic targets on OMEGA

TL;DR

This paper develops a technique to analyze asymmetries in inertial confinement fusion implosions, revealing how symmetry improvements could significantly enhance hot-spot pressure and potentially enable burning plasma conditions.

Contribution

It introduces a combined low- and mid-mode asymmetry reconstruction method for analyzing implosion core data, advancing understanding of performance degradation mechanisms.

Findings

Asymmetries can cause overestimation of areal density.

Correcting asymmetries could increase hot-spot pressure from 56 Gbar to ~80 Gbar.

Symmetry improvements may enable burning plasma conditions.

Abstract

This paper describes a technique for identifying trends in performance degradation for inertial confinement fusion implosion experiments. It is based on reconstruction of the implosion core with a combination of low- and mid-mode asymmetries. This technique was applied to an ensemble of hydro-equivalent deuterium-tritium implosions on OMEGA that achieved inferred hot-spot pressures ~56+/-7 Gbar [S. Regan et al., Phys. Rev. Lett. 117, 025001 (2016)]. All the experimental observables pertaining to the core could be reconstructed simultaneously with the same combination of low and mid modes. This suggests that in addition to low modes, that can cause a degradation of the stagnation pressure, mid modes are present that reduce the size of the neuron and x-ray producing volume. The systematic analysis shows that asymmetries can cause an overestimation of the total areal density in these implosions. It is also found that an improvement in implosion symmetry resulting from correction of either the systematic mid or low modes would result in an increase of the hot-spot pressure from 56 Gbar to ~80 Gbar and could produce a burning plasma when the implosion core is extrapolated to an equivalent 1.9 MJ symmetric direct illumination [A. Bose et al., Phys. Rev. E 94, 011201(R) (2016)].