Abstract
We present a simple method to incorporate nonlocal effects on the Nernst advection of magnetic fields down steep temperature gradients, and demonstrate its effectiveness in a number of inertial fusion scenarios. This is based on assuming that the relationship between the Nernst velocity and the heat flow velocity is unaffected by nonlocality. The validity of this assumption is confirmed over a wide range of plasma conditions by comparing Vlasov–Fokker–Planck and flux-limited classical transport simulations. Additionally, we observe that the Righi–Leduc heat flow is more severely affected by nonlocality due to its dependence on high velocity moments of the electron distribution function, but are unable to suggest a reliable method of accounting for this in fluid simulations.
Highlights
Recent advances in indirect-drive laser fusion at the National Ignition Facility using high-density carbon ablators and low gas-fill [1] have led to neutron yields in excess of 1016 [2]
We present a simple method to incorporate nonlocal effects on the Nernst advection of magnetic fields down steep temperature gradients, and demonstrate its effectiveness in a number of inertial fusion scenarios
Instantaneous snapshots of perpendicular heat flow (Qx), Righi–Leduc heat flow (Qy) and the Nernst-relevant out-ofplane electric field (Ey) at the end of the initial transient periods are respectively presented in the top, middle and bottom panels of figures 2–5 for selected simulations: low and high magnetisation helium runs are presented in figures 2 and 3 corresponding to initial magnetic fields of 0.1 tesla and 2
Summary
Recent advances in indirect-drive laser fusion at the National Ignition Facility using high-density carbon ablators and low gas-fill [1] have led to neutron yields in excess of 1016 [2]. Recent elimination of drive multipliers would not have been possible were it not for large reduction of another tunable parameter—the flux-limiter—which is used to approximate reductions in the electron heat flux from nonlocal effects, selfgenerated magnetic fields and plasma instabilities.
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