Effect of Initial Conditions on Charged Particle Acceleration in a Dense Plasma Focus

Charged particle acceleration has been investigated in a dense plasma focus (DPF) driven by the Hawk pulsed-power generator at the Naval Research Laboratory. Neutron yields of over
$5.0\times 10^{10}$
have been measured at a peak current of
$\mathrm{I}=670\text{kA}$
) significantly above the yield expected at this current based on purely I
^4.4
scaling from conventional DPFs. The high inductance (607 nH) and associated high voltage (640 kV) and fast rise time
$(1.2 \mu \mathrm{s})$
of Hawk are unusual for a DPF driver, as is the initialization of the DPF using local injection of neutral gas and plasma into a vacuum chamber, rather than a conventional neutral gas fill. This method of initialization allows for the selection of an extensive array of initial conditions. A subset of those initial conditions has been explored in conjunction with multi-dimensional MHD simulations to affect the energy of the accelerated ions, as measured by an ion multi-pinhole camera, the neutron yield, as measured by rhodium-foil activation counters, and the end point energy of the emitted neutrons, as measured by neutron time-of-flight detectors.