Using the XFEL to drive the gain of inner-shell x-ray lasers using photo-ionization and photo-excitation processes

Abstract

Four years ago an inner-shell X-ray laser was demonstrated at 849 eV in singly ionized neon gas using the LCLS X-FEL at 960 eV to photo-ionize the 1s electron in neutral neon followed by lasing on the 2p – 1s transition in singly-ionized neon. It took many decades to demonstrate this scheme because it required a very strong X-ray source that could photo-ionize the 1s (K shell) electrons in neon on a time scale comparable to the intrinsic auger lifetime in the neon, which is typically 2 fsec. In this work we model the neon inner shell X-ray laser under similar conditions to those used at LCLS and investigate how we can improve the efficiency of the neon laser and reduce the drive requirements by tuning the XFEL to the 1s-3p transition in neutral neon in order to create gain on the 2p-1s line in neutral neon. We also explore using the XFEL to drive gain on 3-2 transitions in singly-ionized Ar and Cu plasmas.