The PLX-$\alpha$ project: demonstrating the viability of spherically imploding plasma liners as an MIF driver

Under ARPA-E's ALPHA program, the Plasma Liner Experiment-ALPHA (PLX-$\alpha$) project aims to demonstrate the viability and scalability of spherically imploding plasma liners as a standoff, high-implosion-velocity magneto-inertial-fusion (MIF) driver [1] that is potentially compatible with both low- and high-$\beta$ targets. The project has three major objectives: (a) advancing existing contoured-gap coaxial-gun technology to achieve higher operational reliability/precision and better control/reproducibility of plasma-jet properties and profiles; (2) conducting $\sim \pi/2$-solid-angle plasma-liner experiments with 9 guns to demonstrate (along with extrapolations from modeling) that the jet-merging process leads to Mach-number degradation and liner uniformity that are acceptable for MIF; and (3) conducting $4\pi$ experiments with up to 60 guns to demonstrate the formation of an imploding spherical plasma liner for the first time, and to provide empirical ram-pressure and uniformity scaling data for benchmarking our codes and informing us whether the scalings justify further development beyond ALPHA\@. This talk will provide an overview of the PLX-$\alpha$ project as well as key research results to date.\\[4pt] [1] S. C. Hsu et al., IEEE Trans.\ Plasma Sci.~{\bf 40}, 1287 (2012).