Fluid Simulations of a Quasi-steady Plasma Accelerator for Sheared-Flow-Stabilized Z-Pinch Plasma Injection

The Z pinch at Zap Energy is stabilized by shear in the axial flow of plasma that feeds the pinch. While whole-device modeling of the experiment [see I. Datta, IAEA FEC (2023)] gives insights into how this flow is generated, a more detailed understanding of the source of the sheared flow could lead to improved pinch performance. 

 

To study the generation of sheared flow, a simplified model of the injection region has been adopted. In this model, plasma is injected with specified properties at an axially upstream boundary, flows over the nosecone of the center electrode, and is allowed to flow out of the system at the downstream boundary. This simplified model is simulated using resistive magnetohydrodynamics in the WARPXM framework, which uses discontinuous Galerkin finite element methods. A specified current is applied across the upstream boundary, which drives plasma into the pinch. Simulations are allowed to run until a quasi-steady flow is established. The values and radial profiles of injected plasma pressure and density are varied, and their effect on the density, temperature, and flow-shear in the pinch are quantified. The scaling of these quantities with pinch current is also observed.