Spectroscopic Comparisons of X-pinch Tungsten Plasmas to LLNL EBIT Data

Summary form only given. X-pinches produce the high density and temperature plasmas that scale from a few mum to mm in size. They are an excellent source to test new HEDP diagnostics and modeling. X-pinches in particular offer a variety of load configurations that differ in the type of wire connections, number of wires and wire materials. The present work focuses on development of M-shell W diagnostics for HEDP. The experiments were performed on the 1 MA Zebra generator at UNR and the loads were X-pinches and wire arrays with tungsten wires combined with wires from other, lower-z materials (Al and Mo). The identification of x-ray M-shell W spectra in a spectral region from 4 to 8 angstroms from these experiments as well as the theoretical modeling was benchmarked with LLNL EBIT data produced at different energies of the electron beam (Eb). For example, Ni-like W lines from EBIT spectra that dominate in the broad energy range Eb=3-4 keV serve as a good indicator of M-shell W lines in X-pinch and wire array x-ray spectra. In addition, the spectral features on the right from Ni-like lines were higher ionization stages (from Co-to Mn-like ions) while on the left were from lower ionization stages (from Cu -to Ge-like ions). The non-LTE kinetic model of W as well as of Al and Mo were used to distinguish M-shell W from K-shell Al and L-shell Mo spectra and to estimate plasma parameters. The future work with more comparisons with LLNL EBIT data is discussed.