Initial conditions in the hawk dense plasma focus

The 670 kA Hawk pulsed power generator at NRL has been configured as a fast (1.2 µs rise time), high inductance (607 nH) driver for a dynamic dense plasma focus (DPF) load in order to create a testbed for the study of charged particle acceleration mechanisms in imploding plasmas. The current pulse is initiated in a deuterium plasma injected radially by three Marshall guns. This plasma is accelerated through a coaxial region, and pinches onto neutral deuterium injected axially by a gas-puff valve. Promising experimental results along with recent improvements to the Marshall gun design have prompted efforts to better characterize the density profiles produced by the guns. A multichannel heterodyne interferometer focused into a ribbon beam is used to provide time-resolved measurements of the Marshall gun plasma density, allowing parameters to be tuned and mass distributions to be established for a wide range of initial conditions. These interferometric measurements are used in establishing a standard operating condition for the experiment in a high neutron yield regime.