Fully Three-dimensional Simulation and Modeling of a Dense Plasma Focus
A Dense Plasma Focus (DPF) is a pulsed-power machine that electromagnetically accelerates and cylindrically compresses a shocked plasma in a Z-pinch. The pinch results in a brief (about 100 nanosecond) pulse of X-rays, and, for some working gases, also a pulse of neutrons. A great deal of experimental research has been done into the physics of DPF reactions, and there exist mathematical models describing its behavior during the different time phases of the reaction. Two of the phases, known as the inverse pinch and the rundown, are approximately governed by magnetohydrodynamics, and there are a number of well-established codes for simulating these phases in two dimensions or in three dimensions under the assumption of axial symmetry. There has been little success, however, in developing fully three-dimensional simulations. In this work we present three-dimensional simulations of DPF reactions and demonstrate that 3D simulations predict qualitatively and quantitatively different behavior than their 2D counterparts. One of the most important quantities to predict is the time duration between the formation of the gas shock and Z-pinch, and the 3D simulations more faithfully represent experimental results for this time duration and are essential for accurate prediction of future experiments.