Optical source model for the 23.2-23.6 nm radiation from the multielement germanium soft X-ray laser

Distributions of source intensity in two dimensions (designated the source model), averaged over a single laser pulse, based on experimental measureme nts of spatial coherence, are considered for radiation from the unresolved 23.2/23.6 nm spectral lines from the germanium collisional X-ray laser. The model derives from measurements of the visibility of Young slit interferen ce fringes determined by a method based on the Wiener-Khinchin theorem. Out put from amplifiers comprising three and four target elements have similar coherence properties in directions within the horizontal plane correspondin g to strong plasma refraction effects and fitting the coherence data shows source dimensions (FWHM) are similar to 26 mu m (horizontal), significantly smaller than expected by direct imaging, and similar to 125 mu m (vertical : equivalent to the height of the driver excitation). (C) 1999 Elsevier Sci ence B.V. All rights reserved.