Articles you may be interested inParallax diagnostics of radiation source geometric dilution for iron opacity experimentsa) Rev. Sci. Instrum. 85, 11D603 (2014); 10.1063/1.4889776 Calibration and analysis of spatially resolved x-ray absorption spectra from a nonuniform plasma Rev. Sci. Instrum. 83, 073502 (2012); 10.1063/1.4731664 Fluorescence spectroscopy as a diagnostic of the radiation environment in high energy density experiments (invited) Rev. Sci. Instrum. 75, 3655 (2004); 10.1063/1.1785268 Determining the equation-of-state isentrope in an isochoric heated plasma Rev. Sci. Instrum. 75, 2586 (2004); 10.1063/1.1775313Measurements of shock heating using Al absorption spectroscopy in planar targets (abstract) Rev. Sci.Generating a well-characterized hot-dense sample is of great importance to high quality opacity measurements. In this paper, we report on an experimental investigation of the plasma nonuniformity in a radiatively heated iron opacity sample by spatially resolved Al 1s-2p absorption spectroscopy. The iron sample was tamped by plastic at both sides and was heated by thermal x-ray radiation generated in a gold Hohlraum, and an Al layer attached to it was used as a tracer for temperature diagnosis. Spatially resolved 1s-2p transition absorption spectra of the Al tracer were measured by the technique of point-projection-spectroscopy, and temperatures in the sample were obtained by comparing the measured spectra with detailed-term-accounting model calculations, with the density of the sample deduced using a combination of side-on radiography and radiative hydrodynamic simulation. The results showed the existence of axial temperature nonuniformity in the sample, and these temperature variations have been used to explain the shift of iron 2p-3d transition absorption feature along the axial direction of the Hohlraum used to heat the sample successfully. V C 2012 American Institute of Physics. [http://dx.