Study and Assessment of Supersonic Plasma Jets as a Standoff Compression Driver

Spherically imploding plasma liners formed by merging high Mach number plasma jets are a proposed standoff driver for magneto-inertial fusion. The Plasma Liner Experiment (PLX) is currently exploring single jet propagation and two jet merging of supersonic argon plasma jets to assess their potential for use in MIF-relevant plasma liners. Key physics issues include assessing jet densities, jet expansion and cooling during propagation, and potential merging effects such as shock heating. An 8 chord interferometer using a 561 nm diode-pumped solid state laser is being used to make time-resolved density profile measurements of the plasma jets. The interferometer phase shift is sensitive to electron, ion, and neutral atoms and thus is dependent on both plasma ionization fraction, $f$, and total atomic density. Interferometry measurements coupled with spectroscopy and synthetic diagnostic data allow us to infer physics such as plasma density range (10$^{16}$ -- 10$^{17}$ cm$^{-3})$, jet propagation velocity ($\sim $50 km/s), and radial and axial expansion.