Nonequilibrium effects in high-gain inertial confinement fusion

Area of Science:

• * Fusion energy research
• * Plasma physics
• * Computational physics

Background:

• * Recent inertial confinement fusion (ICF) experiments have achieved ignition and target gain.
• * High energy gain and neutron yields in ICF depend on a significant deuterium-tritium (DT) burn fraction.
• * Understanding the fundamental physics of DT burn in high-gain ICF targets is crucial.

Purpose of the Study:

• * To investigate how low-energy alpha particles affect the equilibrium of D and T ions in high-gain ICF targets.
• * To analyze the non-equilibrium effects on DT reactivity.
• * To explore the implications for achieving high energy gain in ICF.

Main Methods:

• * Classical molecular-dynamics (MD) simulations were employed.
• * A hybrid fluid-kinetic model was developed and utilized.
• * Analysis focused on the energy distribution and temperature of D and T ions.

Main Results:

• * MD simulations indicate D and T ion temperatures can diverge by up to 20% of their mean.
• * The DT energy distribution deviates from the Maxwell-Boltzmann function by over 30%.
• * Low-energy alpha particles preferentially heat D ions, leading to temperature separation.

Conclusions:

• * Non-equilibrium effects, driven by alpha particles, are significant in high-gain ICF.
• * The proposed hybrid fluid-kinetic model explains observed phenomena like preferential heating and temperature separation.
• * These non-equilibrium effects have implications for DT reactivity and overall fusion performance.