Work

Correlating hot-electron preheat from the two-plasmon decay instability to ρR degradation for direct-drive implosions on OMEGA

Year: 2025

Type: article

Abstract: Focused experiments were performed with the goal of isolating the impact of hot-electron preheat on compression in deuterium–tritium (DT) layered, direct-drive implosions on OMEGA. Preheat from the hot-electrons generated by two-plasmon–decay (TPD) activity was varied through the incident laser intensity, with the total preheat energy deposited into unablated DT fuel being inferred using hard x-ray measurements. Results show a clear correlation between the inferred preheat levels and ρR degradation that is consistent with a derived, 1D preheat model. A fit to the results also provides an estimated range of ρR degradation from non-preheat sources for the adiabat ≈5implosions used in this study. A follow-up study using targets containing Si-doped (5.5%) CH ablators (CHSi) demonstrated results consistent with mid-Z dopants mitigating TPD activity by showing these targets had almost no ρR degradation as the laser intensity was increased up to levels previously considered damaging.

Source: Physics of Plasmas

DOI: 10.1063/5.0281270