X-ray laser studies of recombining lithium plasmas created by optical field ionization

A high-intensity short-pulse KrF laser system is used to produce fast recombining plasmas by ionization of preformed lithium fluorine plasma targets. Soft-x-ray emission from these plasmas is measured, and population inversions in hydrogenic lithium are observed as the plasma recombines. For relatively low-temperature target plasma columns a nonlinear increase in the intensity of the 2–1 transition in Li III (135 A) is observed with respect to length.