Kilovolt x-ray spectroscopy of a subpicosecond-laser-excited source.

A subpicosecond laser is focused to ${10}^{17}$ W/${\mathrm{cm}}^{2}$ to create an extremely transient Al plasma with a kV radiation time short compared to most of the excitation times. High-resolution spectroscopy is used to analyze the kV line emission from the He- and H-like ions and to determine that the plasma reaches a temperature near 1 keV and cools in less than 10 ps.