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New evidence and impact of electron transport non-linearities based on new perturbative inter-modulation analysis

Author
Abstract

A new methodology to analyze non-linear components in perturbative transport experiments is introduced. The methodology has been experimentally validated in the Large Helical Device for the electron heat transport channel. Electron cyclotron resonance heating with different modulation frequencies by two gyrotrons has been used to directly quantify the amplitude of the non-linear component at the inter-modulation frequencies. The measurements show significant quadratic non-linear contributions and also the absence of cubic and higher order components. The non-linear component is analyzed using the Volterra series, which is the non-linear generalization of transfer functions. This allows us to study the radial distribution of the non-linearity of the plasma and to reconstruct linear profiles where the measurements were not distorted by non-linearities. The reconstructed linear profiles are significantly different from the measured profiles, demonstrating the significant impact that non-linearity can have.

Year of Publication
2017
Journal
Nuclear Fusion
Volume
57
Issue
12
Number of Pages
126036
DOI
10.1088/1741-4326/aa827a
PId
253a5b36e4c90b5327e0cb8eb01a914e
Alternate Journal
Nucl. Fusion
Label
OA
Attachment
Journal Article
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