Effect of Insulator and Anode Geometries on Neutron Yield in A 4.6 Kj Dense Plasma Focus

Abstract

A dense plasma focus device consists of coaxial electrodes, separated by an insulator sleeve inside a gas backfilled vacuum chamber, and powered by a pulsed capacitive discharge. When operated with a deuterium fill gas, neutron production depends on the electrical drive and device geometries. Critically, the tip of the central anode serves as a guide for a dynamic plasma sheath towards the central hot dense Z-pinch. Ongoing experiments using a 4.6 kJ Mather-type DPF exploring the role of electrode geometry with a focus on flat and hemispherical anode tops with and without the presence of the hollow center will be presented. Anode geometry and operating fill pressure affects the relationship between the residual axial motion of the plasma and the inward driving force, which is highlighted in recent studies 1 , 2 . The combination of these two events results in the convergence of the plasma on axis. Neutron yield trends measured using a calibrated activation detector, time of flight measurements, as well as laser probing diagnostics, will be presented.