Feasibility of a hot-electron-pumped K-shell X-ray laser

Amplified spontaneous inner shell emission produced via an ultrafast burst of high energy electrons from a femtosecond laser-produced plasma is proposed as a novel electron-pumped X-ray laser. In this scheme, a population inversion of the upper-laser level is created via impact ionization of atomic inner shells by electron bombardment. Based on the requirement of a positive gain coefficient for amplifying spontaneous K-alpha line emission, a simple pumping threshold is found for the incident electron flux and assessments are made of the feasibility of the scheme for a range of low-Z elements. (C) 1998 Elsevier Science B.V. All rights reserved.