Electron-temperature inhomogeneities along an x-ray laser plasma

The uniformity of electron temperature (${\mathit{T}}_{\mathit{e}}$) along an x-ray laser plasma produced by a line-focused laser was investigated with precise space- and time-resolved measurements. Thomson scattering of a uv probe by the plasma was used to measure the spatial variation of ${\mathit{T}}_{\mathit{e}}$ along the line focus. This characterization was complemented by spatially resolved L-shell x-ray spectroscopy. Electron temperatures obtained from the n=4→2 F-like to Ne-like line ratios agree well with the results from Thomson scattering. Interferometry and x-ray imaging were also used to aid in the diagnosis of the plasma. The inhomogeneities observed are typical of those to be expected in x-ray laser experiments and can lead to significant reduction of the inferred gain on the Ne-like transitions.