Radial and axial variation of stagnated plasma conditions and opactiv studies for K-shell x-ray sources at the Z accelerator

Summary form only given. A variety of experiments have been performed at the Z accelerator to study K-shell X-ray sources, including Al (1.7 keV), Ar (3.1 keV), Ti (4.7 keV), SS (6.7 keV), and Cu (8.4 keV). K-shell scaling theories have shown that the temperature of the plasma necessary to produce the K-shell emission varies with atomic number, T_e = 0.3*Z^2.9 eV, where Z is the atomic number and T_e is the electron temperature. This suggests that for Cu K-shell emission, T_e must be > 5 keV. Spatially resolved, time-integrated spectra can be used to infer plasma conditions, such as electron temperature and ion density, and assess the spatial temperature and density gradients present in the z pinch. For materials such as Cu, the highest measured temperature is observed in isolated regions along the length of the pinch, and is localized near the axis. In fact, for all the K-shell spectra evaluated for this presentation, significant radial temperature gradients are observed, in agreement with observations from monochromatic and filtered pinhole imaging. Opacities, and their gradients, in the K-shell z pinches have also been observed by comparing the line intensities from optically thin dopant materials with those of the main load constituents. Al loads show significant opacity effects, particularly on the axis of the z pinch, where the temperature is highest. By contrast, Cu loads appear to be optically thin for all radial locations.