Development of a Buried Layer Platform at the OMEGA laser to Study Coronal (nonLTE) Plasmas*

A buried layer platform is being developed at the OMEGA laser to study the radiative properties of coronal (non-LTE) plasmas (ne \textasciitilde few 10\textasciicircum 21 /cm\textasciicircum 3, Te \textasciitilde 1 -- 2 keV) of mid to high Z materials. In the current study, the target was a 200 $\mu $m square with equal atomic mixes of gold/iron/vanadium in the center of a 600 $\mu $m diameter, 10 $\mu $m thick beryllium tamper. The thickness of the buried layer was either 1200 A or 1800 A. Lasers heat the target from both sides for up to 4 ns. The size of the microdot vs time was measured with x-ray imaging (face-on) and x- ray spectroscopy (side-on). The radiant x-ray power was measured with a low-resolution absolutely calibrated x-ray spectrometer (DANTE). The temperature was measured from the Fe and V helium-beta complexes. The use of these measurements to deduce emissivity of the target in the 2-3 keV x-ray range and improvements for future experiments are discussed.