Description
Extreme pressures and steep temperature gradients are ubiquitous in inertial confinement fusion (ICF) laser–plasmas. In these regimes, magnetic fields may be self-generated by a variety of mechanisms, most notably the Biermann battery and Weibel instability, which in turn modify thermal transport. Because transport in these conditions is non-local, flux-limited Braginskii models are inadequate, and a full kinetic treatment via the Vlasov–Fokker–Planck (VFP) equation is required.
Recent full-scale kinetic simulations of ICF hohlraums have shown that self-generated magnetic fields can be driven by pressure anisotropies, and lead to instabilities which drive turbulent-like behaviour of the magnetic field itself [1]. Using the VFP code K2, along with hydrodynamic codes Gorgon and CTC, we present a detailed investigation into the physical mechanisms responsible for this novel magnetic field structure. We study the non-local dispersion relations for the collisional magnetothermal instability [2], a magnetic instability composed of feedback between Nernst advection and Righi-Leduc heat flow, as well as the collisional Weibel instability, and how these relate to generation of complex magnetic field structures. Full understanding of these effects is important for improving predictive modelling for next-generation ICF experimental facilities.