Abstract

Recent developments in x-ray laser (XRL) research makes possible the observation of x-ray resonant nonlinear effects (XRNEs). The first obvious choice¹ of the environment for such effects is the plasma consisting of the same ions that gives rise to the laser action itself, both active (i.e., during the lasing process) and passive (at smaller densities). Perfect resonance between the XRL radiation and the corresponding plasma transition could lead to significant nonlinearities, e.g., to the change of the phase front up to 2π across the beam in the SE²⁴⁺ XRL at the length 5-10 cm due to nonlinear refractive index.¹ However, XRNEs in XRL or XRL-like plasmas re quire not only high temperature but also additional x-ray pumping (for passive plasma). We have found a number of resonant couples XRL line-plasma transition in which significant XRNEs can be observed in much simpler conditions attainable by discharge devices, and which cover wavelengths from 236.26 Å to 43.18 Å.

© 1991 Optical Society of America