Six- and Seven-Jet Merging Experiments as an Intermediate Step to Spherical Plasma Liner Formation*

The Plasma Liner eXperiment (PLX) at Los Alamos National Laboratory aims to demonstrate the formation of spherically imploding plasma liners as a low-cost, high-shot-rate, standoff driver for plasma-jet-driven magneto-inertial fusion (PJMIF).  We report results of jet-merging experiments using 2, 3, 5, 6, and 7-gun configurations with Ar, N, Xe, and Kr plasma jets.  The jets were diagnosed using high-resolution and survey spectroscopy, 12-chord heterodyne interferometry, photodiodes, and single- and 12-frame intensified CCD imaging.  Diagnostics were fielded to determine ion and electron temperature, ionization state, electron density, plasma jet velocity, and jet-to-jet balance.  Results show that the jets form shocks that heat the ions up to tens of eV, which then equilibrate with the cooler electrons over several μs.  Electron temperatures are measured to range from 1-3 eV for all gas species.  Interferometry captures non-uniformities in density due to the shocks between merging jets, which could seed eventual instabilities at the liner-target interface .  These results allow for continued assessment of the PJMIF concept.