Simulations of Collisional Effects in an Inner-Shell Mg Solid-Density X-Ray Laser

Inner-shell K-alpha x-ray lasers have previously been created by pumping with the intense x-ray output of free-electron-lasers (FELs) - this first being demonstrated in a Neon gas [1] and subsequently in solid materials [2,3]. Lasing relies on the creation of core-holes on a time-scale short compared with filling via Auger decay. In the case of solid density systems, collisional effects will also be important, yet to date such effects have not been extensively studied. We present here simulations using the CCFLY code of inner-shell lasing in solid density Mg, where we self-consistently treat the effects of the incoming FEL radiation and the atomic kinetics of the Mg system, including radiative, Auger, and collisional effects. We find that collisional depopulation of higher ionisation stages precludes lasing on all but the K-alpha of the neutral system.

[1] Nina Rohringer et al., Nature 481, 488 (2012)

[2] Hitoki Yoneda et al., Nature 524, 446 (2015)

[3] Thomas Kroll et al., Phys. Rev. Lett. 120, 133203 (2018)