X-Ray Line Polarization of Ne-Like Mo Spectra from X-pinch Plasmas

• Published in: IEEE transactions on plasma science 2018-11, Vol.46 (11), p.3820-3828
• Main Authors: Childers, Ryan R., Petkov, Emil E., Kantsyrev, Victor L., Safronova, Alla S., Stafford, Austin, Shlyaptseva, Veronica V., Shrestha, Ishor K., Schultz, Kimberly A., Butcher, Christopher J.
• Format: Article
• Language: English
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Crystals; Density; Depolarization; Diagnostic software; Diagnostic systems; Electron beams; Emission analysis; high energy density (HED) plasma; Ions; L-shell radiation; Line spectra; Linear polarization; Molybdenum; Particle beams; Plasma measurements; plasma pinch; Plasmas; Plasmas (physics); Polarization; Spatial resolution; Spectral emission; Spectrometers; Wires; X ray spectra; X-pinch; X-ray imaging; X-ray line polarization; X-ray spectra and images
• ISSN: 0093-3813; 1939-9375
• DOI: 10.1109/TPS.2018.2863599

Linearly polarized spectral emission is induced by non-Maxwellian electrons with anisotropic velocity distributions through collisional processes with ions in plasmas. X-ray line polarization is a viable diagnostic tool for the study of these electrons, which has been tested in controlled settings, e.g., the electron beam ion trap, but due to strong depolarization effects, has been relatively unexplored in laboratory-produced high-energy-density plasmas. This paper explores the X-ray line polarization for the study of Ne-like molybdenum X-pinch plasmas. Previous polarization studies have focused mostly on K-shell spectral lines, whereas the current paper expands on these studies by investigating L-shell line polarization. The X-pinch is favorable due to its high-density plasma formation, high radiation yield, fixed hotspot location, and reliable electron beam production. L-shell X-ray line polarization and spectral emission of Mo X-pinches were investigated through dual \alpha -quartz ( 2d=6.687 Å) crystal spectropolarimetry with axial and radial spatial resolution. In particular, line polarization is evaluated through a comparative analysis of relative line intensities observed over a range of Ne-like Mo transitions simultaneously recorded with two spectrometers with different sensitivity to polarization. An appreciable degree of X-ray line polarization (up to 15%) is observed in the Ne-like Mo plasmas and analyzed using depolarization effects. These results are the first polarization measurements in high-Z pulsed power plasmas.