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Subsonic radiative ablation model in nonlocal thermodynamic equilibrium fusion plasmas

Xinyu Zhu1, Wenqiang Yuan1, Zhonghai Zhao1, Xiantu He2, and Bin Qiao1,3,*

  • *Contact author: bqiao@pku.edu.cn
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Phys. Rev. Research 8, 013017 – Published 12 January, 2026

DOI: https://doi.org/10.1103/qbcd-hg9s

Abstract

In indirect-drive inertial confinement fusion, the radiative ablation process is vitally important for both building up of a uniform x-ray radiation in the high-Z hohlraum and subsequently capsule implosion ablated by the x-ray radiation. For the former circumstance, various supersonic and subsonic ablation models are developed under the local thermodynamic equilibrium (LTE) assumption. However, for the latter, since the capsule plasma is of low Z, the electron and radiation temperatures are hard to achieve equality; i.e., LTE assumption breaks. So far, how to precisely describe and simulate such a non-LTE ablation process is unknown. Here, by self-consistently including the energy exchange between radiations and electrons into the radiation hydrodynamic (RHD) equations and considering the heat wave velocity as subsonic, we derive and set up a non-LTE subsonic radiative ablation model. Different from previous models where only the Rosseland opacity σR functions, in our non-LTE model, besides σR, the Planck opacity σP plays an important role as well. Our model shows that most characteristic physical quantities of the non-LTE ablation, such as the ablation velocity, ablation pressure, and shock velocity, depend on a combination of σP/σR, while the damping scale length of the radiation temperature scales as L∝(σPσR)1/2. Therefore, we propose using a simple single multiplier ζ on both opacities as σP̃=ζσP and σR̃=ζσR to match the RHD simulation with experimental results, where L, or more practically, the preheating radiation temperature Tpre, can be chosen as a proper benchmark.

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Phys. Rev. Research 8, 013017– Published 12 January, 2026
  • Received 20 July 2025
  • Accepted 7 December 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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