Spectroscopic Measurements of the Formation of a Conical Section of Spherically Imploding Plasma Liners*

The Plasma Liner Experiment-ALPHA (PLX-α) is investigating the merging of supersonic plasma jets into a spherically imploding plasma liner as a driver for use in magneto-inertial fusion (MIF) architectures. 1 The present work is focused on characterizing the merging of six and/or seven plasma jets, converging in a cone of solid angle $0.4 \pi $ over a distance of 1.3 meters. Results from high-speed imaging, photodiode arrays, self-emission visible survey spectroscopy, and self-emission visible high-resolution spectroscopy will be presented, yielding measurements of plasma velocity, number density, electron/ ion temperatures, and mean ionization state pre- and post-merge. Anticipated plasma parameter regimes are $\mathrm {n}\sim 10 ^{15}-10 ^{17}$ cm$^{-3}$, $\mathrm {T}\sim 1-10$ eV, and $\mathrm {v}\sim 50$ km/s, with gas species varied among argon, nitrogen, neon, krypton, and xenon. Images and spectra will be compared with synthetic data generated from 3D fronttracking and smooth-particle-hydrodynamic simulations coupled with atomic physics / opacity analysis codes. Results will inform questions of liner-Mach-number and lineruniformity evolution throughout the jet-merging and subsequent liner-convergence process.