High-performance double-filter soft x-ray diagnostic for measurement of electron temperature structure and dynamicsa

A new soft x-ray (SXR) T e and tomography diagnostic has been developed for MST that can be used for simultaneous SXR spectrum measurement, tomographically reconstructed emissivity, and reconstructed and line-of-sight electron temperature. The diagnostic utilizes high-performance differential transi...

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Bibliographic Details
Published in:Review of scientific instruments 2012-10, Vol.83 (10)
Main Authors: McGarry, M. B., Franz, P., Den Hartog, D. J., Goetz, J. A., Thomas, M. A., Reyfman, M., Kumar, S. T. A.
Format: Article
Language:English
Online Access:Get full text
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Summary:A new soft x-ray (SXR) T e and tomography diagnostic has been developed for MST that can be used for simultaneous SXR spectrum measurement, tomographically reconstructed emissivity, and reconstructed and line-of-sight electron temperature. The diagnostic utilizes high-performance differential transimpedance amplifiers (gain 105−109) to provide fast time response (up to 125 kHz), allowing for the study of plasma structure dynamics. SXR double-foil T e measurements are consistent with Thomson scattering. SXR brightness through a variety of filter thicknesses has been combined with charge exchange recombination spectroscopy (CHERS) impurity density measurements to determine the plasma energy spectrum. Magnetic pickup from the fluctuating magnetic fields in the plasma ( \documentclass[12pt]{minimal}\begin{document}$\tilde{B} \sim 20$\end{document} B ̃ ∼ 20 gauss at 10–20 kHz) has been dramatically reduced by improving the detector and housing design, so that nanoampere diode currents are now measured without interference from the substantial fluctuating magnetic field incident on the plasma facing surface of the probe.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.4740274