Enhancing Neutron Emission From a 500-J Plasma Focus by Altering the Anode Geometry and Gas Composition

The plasma focus (PF) could be a valuable neutron source for Homeland Security applications if high repetition rate with reproducible output is demonstrated. Increasing the neutron yield from a small PF device would contribute to producing a PF neutron source than can compete with other electronic neutron generators for Homeland Security applications and neutron radiography. Two approaches to increase the neutron yield were examined. The first was to alter the anode geometry from a conventional cylinder (20-mm diameter) to a cone (20-5 mm) over a 20-mm length. The neutron-yield increase was 5× in pure D2. The second was to mix inert gases with the deuterium. When 2%, 4%, and 8% Ar and Kr were added to D2, the cylindrical anode showed a maximum 3.6× increase in neutron yield while the conical anode did not show any improvement in neutron yield. However, the operating mass density (pressure) range was increased for the conical anode when inert gases were added.