Improved current scaling and neutron yield for MJ-Class dense plasma focus (DPF) via simulation-guided design.

.The Dense Plasma Focus (DPF) is a well-studied source of short (<100 ns) pulses of ions, neutrons, and x-rays. DPF-based platforms are attractive because they exhibit high yield to energy conversion efficiency and can typically be constructed at a lower cost than traditional accelerators for equivalent output. The scaling of yield versus input current and energy is also favorable, but saturates at the MA and MJ level. [Auluck Phys. Plasmas 2023]. New results on the MegaJOuLe Neutron Imaging Radiography DPF (MJOLNIR) device demonstrate that design changes, led by experimentally validated simulations, have extended neutron yield scaling by two-orders-of-magnitude. In particular, state-of-the-art Particle-In-Cell simulations of the full ~6µs discharge were pivotal in showing an electrode shape redesign would lead to significant plasma temperature increase. The new design produced a record neutron yield of 1.2 × 10^12 with 3.6 MA peak current and 1.3 MJ of stored energy, the highest deuterium-deuterium yield yet reported in the literature. Experimental data are compared to simulations to highlight the two main mechanisms contributing to neutron production: thermonuclear yield from compressional heating of the plasma and beam-target events during subsequent pinch disruption. An extensive suite of diagnostics characterizes the implosion dynamics including: fast framing camera images, interferometry, neutron time-of-flight and neutron source spatial imaging. Finally, we describe a semi-analytical model developed to predict performance for varying discharge and electrode parameters, identifying the contribution of each neutron generation mechanism as well as potential applications of DPFs for plasma material interaction and nuclear resonance transmission analysis. Prepared by LLNL under Contract DE-AC52-07NA27344.