Publications (2)3.32 Total impact
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Article: Implosion dynamics and K-shell x-ray generation in large diameter stainless steel wire array Z pinches with various nesting configurations
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ABSTRACT: Nested stainless steel wire array variations were investigated on the 20 MA Z machine [ R. B. Spielman et al., Phys. Plasmas 5, 2105 (1998) ]. In order to reach experimentally observed electron temperatures near 3.8 keV and excite the K shell, these ∼ 6.7 keV photon energy x-ray sources must be of large initial diameter (45–80 mm) which poses a concern for magnetic Rayleigh–Taylor instability growth. We discuss the implosion dynamics in these large diameter wire arrays, including an analysis of the ablation phase indicating that the prefill material is snowplowed at large radius. Nested array configurations with various mass and radius ratios are compared for instability mitigation and K-shell scaling. Degradation of the K-shell x-ray power and yield was observed for shots that did not have simultaneous implosion of the outer and inner wire arrays. Shots that were designed per this constraint exhibited K-shell yield scaling consistent with the model of J. W. Thornhill et al. [IEEE Trans. Plasma Sci. 34, 2377 (2006) ] which had been benchmarked to single array results. This lends confidence to K-shell yield predictions using this model for future shots on the refurbished Z machine. Initial results employing a triple nested wire array to stabilize the large diameter implosion are also reported.Physics of Plasmas 12/2008; 15(12):122703-122703-21. · 2.15 Impact Factor -
Article: Measurement of the 0.1- to > 10-keV Energy Distribution for an Argon Z-Pinch at the 15-MA Level
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ABSTRACT: We report an approximate energy distribution (coarse spectrum) over the range ~0.1 to > 10 keV for the X-ray output of an argon Z-pinch. The tests, conducted at ~15-MA peak current, utilized an 8-cm diameter double-shell nozzle. Sze (2001) have previously described the performance of this Z-pinch with emphasis on the K-shell line emission at ~3 keV. Additional measurements that address the non-K-line output of the Z-pinches are presented here. On the one hand, > 4-keV photons due to the free-bound continuum constitute a significant fraction, almost 30%, of the nominal K-shell emission. On the other hand, the sub-3-keV L-shell lines and continuum show distinctive time histories and significant yields. These nonresonance-line emissions are important for a more complete understanding of the implosion physics, for proper analysis of diagnostic responses, and for their effects upon objects exposed to the Z-pinch's radiationIEEE Transactions on Plasma Science 03/2007; · 1.17 Impact Factor
