Speaker
Description
The 650 kA Hawk pulsed power generator at NRL has been configured as a fast (1.2 μs), high inductance (607 nH) driver for a dynamic dense plasma focus load. The current pulse is initiated in a deuterium plasma that is 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 tweaks to the Marshall gun design have prompted efforts to better characterize the density profiles produced by the guns. A multi-channel heterodyne interferometer focused into a ribbon beam is used to provide time-resolved measurements of the Marshall gun plasma density in a separate test chamber, allowing parameters to be varied and mass distributions to be established for a wide range of initial conditions. The same instrument is fielded in situ during Hawk DPF shots, with the ribbon beam probing the plasma as a function of radial position across the A-K gap, measuring the density pileup as the plasma is driven downstream. These density measurements are presented alongside electrical data and radiation measurements, to infer the time-evolution of the plasma through the pinch.
- This work was supported by the Naval Research Laboratory Base Program, the Office of Naval Research under Grant # N62929-16-1-2192, and the Ministry of Education, Youth, and Sports of the Czech Republic under grant no. LTAUSA-17084.
