Interfacial mixing in high-energy-density matter with a multiphysics kinetic model

Area of Science:

• Plasma Physics
• Computational Physics
• Kinetic Theory

Background:

• The Bhatnagar-Gross-Krook (BGK) model is a kinetic model used in plasma physics.
• Previous BGK models were limited to spatially homogeneous systems and lacked multiphysics capabilities.
• Simulating warm dense matter, particularly for inertial confinement fusion (ICF) targets, requires models that can handle large spatiotemporal scales and high temperatures.

Purpose of the Study:

• To extend the multispecies, multitemperature BGK model to include multiphysics capabilities.
• To enable modeling of a wider range of physical conditions, including one spatial dimension.
• To apply the enhanced model to study warm dense matter scenarios relevant to ICF.

Main Methods:

• Extended the BGK model to one spatial dimension.
• Incorporated an atomic ionization model, accurate collision physics, self-consistent electric fields, and electronic screening degeneracy.
• Applied the model to simulate the ablator-fuel interface of an ICF target under heating.

Main Results:

• The kinetic model significantly extends the temperature and spatiotemporal scales compared to molecular dynamics simulations.
• Observed hydrogen jetting from the ablator into the fuel during early implosion stages.
• Compared Fickean diffusion, electrodiffusion, and barodiffusion contributions to material transport.

Conclusions:

• The enhanced BGK model provides a powerful tool for simulating warm dense matter at larger scales than previously possible.
• The study highlights the importance of kinetic effects and various diffusion mechanisms in ICF implosions.
• Further investigation into kinetic effects like anisotropic distributions and velocity separation is needed to determine the applicability of hydrodynamic models.