Analyzing spatially resolved line spectra emitted by Z pinches

Abstract

The spatial profiles of key physical variables such as electron temperature and density are crucial in determining the overall radiating efficiency of a Z pinch as well as the emitted photon energy distribution. The present work uses spatially resolved x-ray lines emitted from shots taken on the 4 MA Double EAGLE generator [C. Deeney et al., Phys. Rev. A 44, 6762 (1991)] at Maxwell Physics International to infer such profiles. The loads were arrays of 15 wires consisting of 95% Al, 5% Si, producing nearly 50 kJ of K-shell radiation with relatively long pulsewidths of 41–43 ns. It is found that the spatial profile of the He-like intercombination to resonance line ratio is critically affected by self-absorption and re-emission (scattering) of resonance line photons emitted from the hot, dense interior of the pinch. This ratio cannot be correctly interpreted without taking the scattering into account. Also, at densities somewhat lower than those achieved by these pinches, this line ratio becomes more temperature than density dependent. The inferred temperature gradient is much less steep than that which had been diagnosed previously for a pinch emitting a much shorter x-ray pulsewidth of 13 ns.

A non-LTE kinetic model for quick analysis of K-shell spectra from Z-pinch plasmas

“…In the past few decades, analysis of K-shell spectra using population kinetics models has gradually been recognized as an effective method to estimate the ionization state distribution, electron temperature and electron density of low-to moderateatomic number z-pinch plasmas [3], [4]. Many non-LTE models, codes and calculation results have been developed and published to add to the understanding of the behavior of z-pinch plasmas [5]- [7] .…”

Time-resolved K-shell line spectra measurement of the imploding aluminum wire arrary

“…The disadvantages of this technique are the limited availability of different filters, complicated retrieval algorithm and poor accuracy owing to little difference of the responsivity function between each filter [11]. In the past few decades, analysis of Kshell spectra using population kinetics models has gradually been recognized as an effective method to estimate the ionization state distribution, electron temperature and electron density of low-to moderate-atomic number zpinch plasmas, and there have many computing codes [12,13] with sufficient accuracy developed to estimate the electron temperature and density by comparison of the relative intensities of different K-shell line spectra [14][15][16][17][18]. That suggests the measurement of the K-shell line spectra by integration of the time-resolved detectors into the x-ray spectrometer may be another way for obtaining the parameters information about the z-pinch plasmas.…”