Possibilities for achieving x-ray lasing action by use of high-order multiphoton processes

Abstract

We consider some possible mechanisms for producing gain in the 10-nm spectral region. They involve the creation of a population inversion in a confined plasma column by selective excitation of multiply charged ions through absorption of many (>10) ultraviolet photons. Calculations of the energy-level structure of ions in the Kr isoelectronic sequence show singly and multiply excited states that provide suitable strong radiative transitions in the region of 10 nm. The potential for achieving x-ray lasing action in Kr-like ions pumped by a KrF excimer laser is most favorable at high Z.