Radiative properties of L-shell molybdenum and K-shell aluminum plasmas from planar and cylindrical wire arrays imploded at 1 MA Z-pinch generator.

摘要

University-scale Z-pinch generators are able to produce plasmas within a broad range of temperatures, densities and opacity properties depending on the configuration, size and mass of wire array loads and wire materials in cost effective experiments. Similar Z-pinch plasmas are produced and studied at larger Z-pinch generators such as the 26 MA Z generator at Sandia National Laboratories. Thus, university-scale generators play an important role in the development of better understanding of wire array implosions and in the design and testing of new wire array configurations that can be also applied at higher currents. Recently, the novel wire array configuration, planar wire array (PWA), was tested and implemented in wire array research at UNR. Implosion of planar wire arrays on the 1 MA Zebra generator at UNR showed energy conversion enhancement, radiation pulse shaping capability, high radiation yields and high L-shell plasma temperatures. In particular, radiation yields of Mo DPWA that exceeded ET ∼23 kJ and P peak ∼1 TW were measured.;In this dissertation, L- and M-shell of Mo and K-shell of Al and Mg radiation from implosions of planar wire arrays (single, SPWA and double, DPWA) and cylindrical wire arrays (conventional, CWA and compact, CCWA) on the 1 MA Zebra at UNR were analyzed. In addition, nested wire arrays with alloyed Al wires were studied at 1 MA Cobra generator at Cornell University. The experimental data from the full set of diagnostics: PCD, XRD and current signals, and x-ray pinhole images and spectra, were implemented in this research. Non-LTE models were applied to model spatially resolved time integrated, as well as time-gated spatially integrated spectra from Al, Mg and Mo plasmas. In particular, modeling of L-shell Mo spectra from the SPWA showed the highest electron plasma temperature from PWAs (Te∼1400 eV). Axial gradients of electron temperatures and densities as well as the percentage of radiating mass were modeled and compared. Mo PWA generates bright spots or clusters of bright spots along the axial direction, and temperature and density inside these bright spots were also investigated. M-shell Mo model has been developed to diagnose Mo EUV plasmas from the implosions of wire arrays and laser-target interactions. Radiation magneto-hydrodynamics modeling was performed to analyze the mechanism of Z-pinch plasma heating in the presence of strong density gradients. The novel Wire Dynamics Model was used to analyze the implosion dynamics of SPWA, DPWA, CWA and CCWA loads. Plasma electron temperature, density and opacity properties of optically thick Al plasmas were diagnosed using alloyed Al wires with different small concentration of Mg (from 0.8% to 5%).