Effect of high-z dopants on neutron output from a dense plasma focus

Summary form only given. The Dense Plasma Focus (DPF) produces a 10-40 ns (FWHM) neutron pulse, with output scaling as I⁴ over a wide range (~10 kA-1 MA) of peak current (I). Typical neutron yield per pulse is 10⁶ n/pulse at ~100 kA, scaling to ~10⁸ n/pulse at ~300 kA. It is well known that the neutron output from a DPF is due to a combination of thermal fusion along with so-called beam-target fusion, in which a run-away population of fast ions (D⁺ or T⁺) along and near the axis of the pinch interacts with dense spots of plasma to induce fusion more efficiently. We had earlier measured a five-fold increase in neutron output when the D₂ gas fill in a 130 kA DPF was mixed with 8% (by mass fraction) of Ar while maintaining the total mass. However, the implosion time changed substantially in these experiments as the mass fraction of Ar increased. In this paper we explore the neutron yield for different Ar mass fractions while maintaining the optimum implosion time for a pure D₂ implosion. Data presented is an average over ~100 shots at each Ar mass fraction allowing for a statistically significant comparison of output vs. the Ar fraction.