X-ray spectral diagnostics of neon photoionization experiments on the Z-machine

We report on an initial spectroscopic study of low-density, x-ray photoionized neon with x ray spectroscopy. These experiments, carried out on the Z-machine at Sandia, are optimized to produce a gradient free, collisionless plasma, and to explore issues related to the rapid x-ray photoionization of relatively cold, low-density plasmas. The initial experiments used time-integrated absorption spectroscopy, backlit by the pinch radiation, to determine the ionization balance in the gas cell. Future experiments will use time-resolved spectroscopy in both absorption and emission. The emission spectra are expected to be similar to those seen from photoionized astrophysical sources, such as x ray binaries. Indeed, in addition to addressing basic plasma and atomic physics issues, these experiments are designed to help the astrophysical community better understand the new, high-resolution spectra being produced by the Chandra and XMM-Newton telescopes, and to benchmark spectral synthesis codes. With the launch of NASA's Chandra x-ray telescope in 1999, high-resolution x ray spectroscopy of cosmic sources beyond the solar system became possible. This telescope and the similar XMM-Newton telescope, launched by the European Space Agency later that same year, comprise large (collecting areas of roughly 1 m2) nested hyperbolic and parabolic mirrors, instrument packages that include grating spectrometers (transmission