Diagnostics and results from coaxial plasma gun development for the PLX-$\alpha$ project*

We present results from the diagnostics used during development of the contoured gap coaxial plasma guns [1] for the PLX-$\alpha$ project at LANL. Plasma-jet diagnostics include fast photodiodes for velocimetry, a ballistic pendulum for total plasmoid momentum, and interferometry for line integrated density. Deflectometry will be used for line integrated perpendicular density gradients. Time-resolved high-resolution spectroscopy using a novel detector and time-integrated survey spectroscopy are used for measurements of velocity and temperature, as well as impurities. We will also use a Faraday cup for density, fast imaging for plume geometry, and time-integrated imaging for overall light emission. Experimental results are compared to the desired target parameters for the plasma jets (up to $n \approx 2\times 10^{16}\,\rm{cm}^{-3}$, $v\approx 50\, \rm{km/s}$, mass $\approx 5\, \rm{gm}$, radius$ = 4\, \rm{cm}$, and length $\approx 10\,\rm{cm}$).\newline [1] Witherspoon et al., Rev. Sci. Instr. \textbf{80}, 083506 (2009).