Inner-shell photo-ionized x-ray laser schemes for low-Z elements

Gain calculations for inner-shell photo-ionized lasing in C at 45 A are performed. An incident x-ray source represented by a 150 eV blackbody with a rise time of 50 fsec gives a gain of order 10 cm-1. The x-ray source and thus the driving optical laser requirements are significantly reduced as compared to what is needed for Ne at 15 A. We expect that existing ultra-short pulse lasers can produce the required x-ray source and thus produce a table-top x-ray laser at 45 A