SIMULTANEOUS MEASUREMENT OF LOCAL GAIN AND ELECTRON-DENSITY IN X-RAY LASERS

X-ray lasers (XRLs) have experimental average gains that are significa ntly less than calculated values and a persistently low level of spati al coherence. An XRL has been used both as an injected signal to a sho rt XRL amplifier and as an interferometer beam to measure two-dimensio nal local gain and density profiles of the XRL plasma with a resolutio n near 1 micrometer. The measured local gain is in agreement with atom ic models but is unexpectedly spatially inhomogeneous, This inhomogene ity is responsible for the low level of spatial coherence observed and helps explain the disparity between observed and simulated gains.