X-ray Spectroscopic Studies of X-pinch Plasma Micropinches with ∼ 10 ps Resolution

Abstract

X pinches have been successfully developed as point sources of soft x-rays for radiography, but the parameters of the micropinch plasmas that produce the x-rays are not well established. To determine micropinch conditions, time-resolved x-ray spectra produced by 2- and multi- wire X pinches have been collected using an x-ray streak camera with <10 ps time resolution. Together with a spherically-bent mica crystal spectrograph, the streak camera recorded 1-10 keV radiation emitted from X pinches made from different wire materials. Spectral features varied on time scales ranging from 10 to 300 ps, depending on the wire material. From the spectra, we infer that some micropinches produced within exploding wire X pinches are near solid density and have an electron temperature above 1 keV. For example, an electron density up to about 3×l023/cm3 and an electron temperature up to about 2.5 keV were inferred from the He-like and H-like lines from a Ti X pinch. Results demonstrate that x-ray spectra must be recorded with sub-ns time-resolution to obtain plasma conditions in micropinches.