Simulations of a Dense Plasma Focus on a High Impedance Generator

Abstract

NRL is embarking on a program to study the connection between plasma instabilities and fast ion acceleration for neutron production on a Dense Plasma Focus (DPF). The experiments will be performed on the HAWK generator (665 kA, 1.5 micro-sec), which has a high inductance (619 nH). There is a conjecture that the neutron yield on a DPF may be enhanced on a high impedance generator since the assembly on axis will not significantly reduce the current drive. Furthermore, to prevent upstream breakdown during the implosion there are plans to inject the gas load as a plasma far from the insulator stack. As a propaedeutic study, we performed MHD simulations using the Athena code. Athena is an Eulerian 3D, unsplit finite volume MHD code that includes shock capturing with Riemann solvers and resistive diffusion for the magnetic field components. The simulations are coupled to an equivalent circuit model for HAWK. This initial report will examine the dynamics and implosion time as a function of the initial injected plasma distribution and study the implications of non-ideal effects.