Tabletop x-ray lasers*

Abstract

Details of schemes for two tabletop size x-ray lasers that require a high-intensity short-pulse driving laser are discussed. The first is based on rapid recombination following optical-field ionization. Analytical and numerical calculations of the output properties are presented. Propagation in the confocal geometry is discussed and a solution for x-ray lasing in Li-like N at 247 Å is described. Since the calculated gain coefficient depends strongly on the electron temperature, the methods of calculating electron heating following field ionization are discussed. Recent experiments aimed at demonstrating lasing in H-like Li at 135 Å are discussed along with modeling results. The second x-ray laser scheme is based on the population inversion obtained during inner-shell photoionization by hard x rays. This approach has significantly higher-energy requirements, but lasing occurs at very short wavelengths (λ≤15 Å). Experiments that are possible with existing lasers are discussed.