A Study of Exploding Wire Plasmas by X-Ray Absorption

Adam Cahill, Cornell University

A spectrometer utilizing the geometry of an elliptically bent mica crystal has been developed to study the absorption spectra of hot and azimuthally symmetric plasmas[1]. The spectrometer disperses probing X-rays with a doubly curved elliptical mica crystal before focusing them onto a sample plasma. Dispersing the X-rays before interaction with the sample ensures that sample radiation appears not as lines but only as a uniform background in the data that does not corrupt the absorption spectrum. The experiment examines the helium-like and hydrogen-like resonance and satellite lines (8.3-9.5 Å) of Mg in order to provide diagnostic information about a sample plasma.

Here we present spatially and temporally resolved absorption spectra obtained from single wires and hybrid x-pinches samples. The radiation source is generated by a 50 μm-diameter gold wire in a hybrid x-pinch configuration. The absorbing samples are composed of Al 5056. This aluminum alloy is composed of 5 percent Mg that acts as a diagnostic ion for the experiments. Radiographs of the samples are presented. The design of the spectrometer allows both measurements to be taken simultaneously. Data is analyzed to determine temperature and density profiles for each absorbing sample.

1A.D. Cahill et al., “A doubly curved elliptical crystal spectrometer for the study of localized X-ray absorption in hot plasmas,” Rev. Sci. Instrum. 85, 103114 (2014).

Abstract Author(s): Adam D. Cahill, Sergei A. Pikuz, Tania A. Shelkovenko, David A. Hammer