Diffusivity in asymmetric Yukawa ionic mixtures in dense plasmas.

Area of Science:

• Plasma Physics
• Computational Physics
• Astrophysical Plasmas

Background:

• Astrophysical and inertial confinement fusion plasmas involve complex ion mixtures.
• Accurate calculation of interdiffusion coefficients is crucial for understanding plasma behavior.
• Existing theoretical models may not fully capture diffusion dynamics in asymmetric plasmas.

Purpose of the Study:

• To compute the interdiffusion coefficient for asymmetric mixed plasmas using molecular dynamics.
• To investigate plasma conditions relevant to astrophysical and fusion energy research.
• To compare simulation results with established theoretical predictions.

Main Methods:

• Employed molecular dynamics (MD) simulations for deuterium-argon mixtures.
• Simulated 30,000-120,000 ions interacting via the Yukawa potential.
• Utilized the Green-Kubo approach to calculate species diffusivity from autocorrelation functions.

Main Results:

• MD simulations show that a common expression for interdiffusion coefficient overestimates the actual value.
• Cross-correlation terms in ion velocities significantly impact diffusion in asymmetric plasmas.
• Discrepancies observed between MD results and kinetic theories, with MD suggesting a larger Coulomb logarithm.

Conclusions:

• The widely used formula for interdiffusion coefficients is inadequate for asymmetric mixed plasmas.
• Cross-correlation effects are a key factor in diffusion dynamics of these plasmas.
• Further refinement of kinetic theories is needed to align with MD simulation findings for accurate plasma modeling.