Dense plasma focus (DPF) devices are compact pulsed plasma systems capable of producing intense bursts of neutrons, X-rays, and energetic particles, with their performance strongly governed by the electrode geometry. In this work, a two-dimensional relaxation magnetohydrodynamic (MHD) model is employed to systematically investigate the effects of key geometric parameters on the discharge dynamics and neutron production characteristics of a deuterium-filled DPF device, elucidating the underlying physical mechanisms and identifying optimal parameter ranges.

The numerical model self-consistently describes the macroscopic evolution of the plasma sheath driven by electromagnetic forces after breakdown, including the axial acceleration along the anode, the subsequent radial implosion toward the axis, and the formation of a transient high-density plasma column. The ionization degree is incorporated through a Saha equilibrium correction to ensure thermodynamic consistency of the plasma state, while the neutron yield is evaluated by considering only the thermonuclear contribution from D-D fusion reactions. Kinetic effects such as beam–target interactions and non-Maxwellian ion populations are not neglected in the present model, and their possible influence is discussed in the context of the model applicability and limitations.

For the optimal geometric configuration, the simulated discharge current, neutron production rate, and plasma thermodynamic quantities exhibit clear temporal coherence. The evolution of the discharge current shows a rapid rise culminating in a peak approaching the end of the radial compression stage, accompanied by a pronounced neutron burst confined to a narrow time window. This indicates that neutron generation is closely associated with the formation of a highly compressed, high-temperature plasma region during the late implosion stage. The neutron production rate spans several orders of magnitude over the course of the discharge, highlighting the highly transient nature of the fusion process.

To assess the impact of ionization modeling, the temporal evolutions of the ionization degree and the characteristic plasma temperature with and without the Saha correction are compared. The results show that, during the partially ionized phase, the Saha-corrected temperature is systematically higher than that obtained under the assumption of full ionization. This behavior arises from the redistribution of internal energy due to ionization equilibrium effects, thereby modifying the effective particle number density. As the discharge progresses and the ionization degree approaches unity, the two temperature profiles gradually converge, indicating that ionization effects become less significant in the highly ionized regime. The characteristic temperature, defined as the average temperature at the plasma sheath front, exhibits a distinct peak concurrent with the neutron burst, reflecting strong energy localization during compression.

The simulated two-dimensional ion density distributions further reveal the staged evolution of the plasma, from axial current sheath motion to radial convergence and subsequent dense axial column formation. The spatial and temporal features obtained in the present simulations are in good qualitative agreement with typical numerical and experimental DPF observations in the literature.

Overall, although the present MHD model does not explicitly account for kinetic beam-target mechanisms, the results demonstrate that geometric parameters decisively govern the macroscopic compression dynamics and thermonuclear neutron production trends. The findings provide meaningful guidance for electrode design and parameter optimization of DPF devices, particularly in terms of improving plasma compression efficiency and fusion performance in thermally driven regimes.