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Experiments in the last few years at the 20-MA Z Accelerator have produced significant K-shell X-ray output from a variety of initial load materials, including aluminum (1.7-keV photons, > 400-kJ yield), argon (3.1-keV photons, > 300-kJ yield), titanium (4.8-keV photons, 100-kJ yield), stainless steel (6.7-keV photons, > 50-kJ yield), and copper (8.4-keV photons, 20-kJ yield). K-shell scaling theories developed at the Naval Research Laboratory [K. G. Whitney et al., Phys. Rev. E 50, 2166 (1994)] in the 1990s were benchmarked against the Al K-shell emission data from < 10-MA facilities. The experiments at Z have not only led to a heuristic validation of this original theory but have also provided the data to fine tune the models for application to higher photon energies and for extension to higher current generators. The upgrade of the Z Accelerator to ZR, which will provide 26 MA to a Z-pinch load, should increase the radiated K-shell output for sources previously fielded at Z and will extend the range of photon energies where measurable radiation can be observed, which is likely up to 13 keV. A summary of the K-shell experiments at Z is presented, as well as an overview of the modified empirical-scaling theory. Proposed load configurations for ZR are discussed, as well as predictions for K-shell output. Index Terms--K-shell radiation, plasma pinch, X-ray measurements, X-ray production.

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 et al. (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 radiation. Index Terms--X-ray diagnostics, X-ray spectra, Z-pinches.

This paper presents theoretical extrapolations for the multi-keV X-ray radiation production capability of the 26-MA ZR accelerator at Sandia National Laboratories, which is scheduled to become available for experiments in 2007. These extrapolations are based on scaling models and ideas that have been developed over the years. These models and ideas have evolved and been refined through the process of benchmarking one-dimensional non-local-thermodynamic equilibrium magnetohydrodynamic model results to experimental K-shell yields and powers as well as inferred temperatures and densities. For this ZR assessment, the models are first benchmarked to K-shell yields obtained from argon, titanium, stainless-steel, and copper Z experiments and then they are applied to extrapolate yield predictions to the ZR machine. Extrapolations are based on 2-cm-length loads and similar wire configurations and nozzle designs as those employed in Z experiments. Projected K-shell yields for Ar (photon energy ~3 keV), Ti (~5 keV), stainless steel (~7 keV), and Cu (~8.6 keV) are 520, 300, 200, and 80 k J, respectively. In addition, the high-energy free-bound continuum emission above 10 keV is calculated to be 40 kJ on ZR. Index Terms--K-shell radiation, magnetohydrodynamics, plasma pinch, X-ray production.

Reports on the ionization and radiation dynamics of carbon ablation plasmas. Analysis of the interaction of a proton beam as it heats and ablates a carbon target; Overview of the ionization dynamics model; Ablation of a carbon target by a proton beam.

This paper presents explicit analytical formulas relating the X-ray yields in various energy bins of the free-bound recombination continuum to the mass, temperature, dimensions, and confinement time of the plasma participating in the K-shell emission. Estimates based on these formulas support the idea that K-shell recombination continuum radiation of argon, titanium, and iron can be a viable alternative to the K-shell line radiation of higher atomic number ions for advancing the operation of Z-pinch plasma radiation sources into the warm X-ray photon energy range of 10-20 keV. The potential of the refurbished Z accelerator for generating multikilojoule radiation yields in this energy range via recombination continuum is assessed. [ABSTRACT FROM AUTHOR]

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 et aL (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-key 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 radiation. [ABSTRACT FROM AUTHOR]