Experimental vs. Simulated yield scaling with capsule size for DT-layered implosions on the OMEGA laser

To assess the proximity to ignition [1] of DT-layered implosions on OMEGA, neutron yields must be extrapolated to larger capsule sizes relevant to NIF-like laser energies. Previous dedicated experiments on OMEGA [2], designed to evaluate yield scaling for size scaling factors of 1.25x, have shown results that align closely with the traditionally employed hydrodynamic scaling law (Y ~ S^4.3) but exceed the scaling predicted using one-dimensional radiation hydrodynamic calculations (Y ~ S^3.45). It was suggested that the discrepancy in the observed scaling is influenced by the non-scaling of seed amplitudes of various 3D perturbations.

We present results from similar size-scaling experiments but using implosions with silicated-CH ablators—rather than the CD ablators employed in previous experiments. These results again support the hydrodynamic scaling (Y ~ S^4.3), yet they exhibit an even greater discrepancy with the yield scaling predicted by 1D simulations (Y ~ S^2.7). These findings indicate that limitations in the energetic modeling may also contribute to the observed discrepancies in the yield scaling with size. The focus of this talk is exploring various factors influencing the yield scaling in 1D simulations to diverge from hydrodynamic scaling.

[1] R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015).

[2] C. A. Thomas et al., Bull. Am. Phys. Soc. (2024).