Effect of beryllium filter purity on x-ray emission measurements

M.B. McGarry, P. Franz, D.J. Den Hartog, J.A. Goetz

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Abstract

Beryllium foils of the purity grade typically specified for use as filters in soft x-ray (SXR) diagnostics may contain sufficient heavy element impurities to distort the energy transmission response of the filter. Electron microprobe analysis of the foils used in the Madison Symmetric Torus (MST) SXR tomography diagnostic revealed an impurity content of ∼0.3% fractional abundance by weight, comprised primarily of iron, zirconium, chromium, and nickel. These impurities lower the peak filter transmission in the energy range of the detector and alter the shape of the transmission curve. As a result, foil impurities introduce errors in any general measurement where radiation is being filtered. For example, neglecting the effect of impurities on filter transmission leads to large systematic errors (50%) in the electron temperature measured using the SXR double-filter technique on MST.
Original languageEnglish
Article number125018
Pages (from-to)-
JournalPlasma Physics and Controlled Fusion
Volume56
Issue number12
DOIs
Publication statusPublished - 1 Dec 2014
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

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