Femtosecond X-ray laser schemes using electron-impact inner-shell ionization and Coster-Kronig processes

Abstract

X-ray laser schemes are proposed in which the upper level of a lasing transition is pumped via electron-impact, inner-shell ionization by femtosecond high-energy electron pulse and the lower level is emptied rapidly due to Coster-Kronig processes. The relevant characteristics of the L1M2,3, L2,3M1, M4,5N2,3, KM3, L3N1, and L3N5 transitions have been tabulated. Among these transitions, the L2M1 transition for Z=22 to 32 has the least stringent pumping requirements for achieving inversion in the 20-40 Angstrom wavelength range. Computer simulations predict that small signal gains of 3.8 cm(-1) at 3.09 nm (401 eV) in Ti could be achieved for an electron pulse of 10-fs duration and with maximum electron density of 10(21) cm(-3).