Study of neutron production from a 4.4 kJ dense plasma focus

The Dense Plasma Focus (DPF) is a pulsed power Z-pinch configuration capable of producing neutrons and energetic electron/ion beams from a high density and high temperature deuterium plasma pinch. The length of insulator sleeve plays an important role in the dynamics of plasma sheath which affects the pinch quality and the neutron yield. Experiments are carried out using a 4.4 kJ (250 kA, 21 kV) Mather-type DPF equipped with a Be-activation detector and laser probing diagnostics at fill pressures ranging from 2 to 8 torr D2, where varying insulator sleeve length (1/8-2/5 the anode length) is investigated. Neutron production with an intermediate insulator sleeve length equal to 1/3 the anode length demonstrated the lowest shot-to-shot variation and greatest neutron production on average. An optimal fill pressure for neutron production is identified between 4-5 torr, resulting in >108 neutrons/pulse. Deuterium fill pressures above 6 torr result in plasma filamentation that degrades the performance of the DPF.