Three-dimensional Modelling with FLASH of the Implosion Dynamics of a Reactor-scale Version of the Plasma Liner Experiment Platform*

This work presents 3D FLASH simulations of a reactor-size version of the Plasma Liner Experiment (PLX), a Plasma Jet-driven Magneto-Inertial Fusion (PJMIF) platform at Los Alamos National Laboratory (LANL). Work on PLX is aimed towards the development of a pulsed (~1 Hz) reactor with moderate gains (3-30 in 1D). The method involves a constellation of plasma guns which shoot magnetized DT jets at the center of a spherical chamber. It is expected that the mostly toroidal fields from the individual DT jets become entangled into a randomized B-field as the jets merge to assemble the spherical target. This process is followed by a series of unmagnetized Xe plasma jets which merge inflight into a liner shell of ≈ 25 MJ kinetic energy at 100 km/s to implode and confine the DT gas. The assembly of the target has been previously shown, with PIC (OSIRIS) and MHD (FLASH) simulations, to be a collisional process, whereas the assembly of the liner is initially dominated by kinetic effects. Therefore, FLASH can model the liner-target interaction only once the liner material is collisional (i.e., once the shell has fully formed and propagates radially inwards to implode the target). For this reason, our reactor-scale 3D simulations start after the assembled liner shell and target first come into contact, at a convergence ratio (CR) ≈ 6. This allows us to investigate the dynamics of the implosion in a manner consistent with prior work in 1D and provides information about mixing along the Xe-DT interface. Preliminary simulations indicate moderately high DT ion temperatures (>2 keV) and densities (2.5 g/cc), as well as large magnetic field strengths (10⁷ G) inside the compressed target. The conditions reached imply electron and ion Hall parameters χ_e ≈ 10²−10³, χ_i ≈ 1−10 respectively, and β ≤ 1.