THEORETICAL INVESTIGATION OF AN ULTRASHORT-PULSE COHERENT X-RAY SOURCE AT 45 ANGSTROM

A scheme to obtain ultrashort-pulse coherent x rays, via population in version following inner-shell photoionization, is analyzed for C at 45 Angstrom. We calculate that a driving laser with a pulse duration of 40 fs, a 10 mu mX1 cm line focus, and an energy of 1 J gives an effect ive gain length product (gl) of 10. At saturation (gl similar to 18) w e expect an output of similar to 0.1 mu J per pulse. The short duratio n of x-ray lasing (<100 fs) combined with a 10-Hz repetition rate (P-a vg=1 mu W) makes this source of coherent x rays ideal for pump-probe e xperiments to study fast dynamical processes in chemistry and material science. [S1050-2947(98)05902-2].