Investigation of higher harmonics of electron cyclotron emission using Fourier transform spectroscopy in Wendelstein 7-X

Wendelstein 7-X stellarator has a high aspect ratio which makes the electron cyclotron harmonics spectrally well separated and more straightforward to interpret compared to a tokamak with a low aspect ratio. For fusion reactor relevant plasma operations, Wendelstein 7-X is planned to operate at high...

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Bibliographic Details
Published in:Journal of instrumentation 2020-09, Vol.15 (9), p.P09024-P09024
Main Authors: Chaudhary, N., Oosterbeek, J.W., Hirsch, M., Hoefel, U., Wolf, R.C.
Format: Article
Language:English
Subjects:
Cyclotrons
Density
Diagnostic software
Diagnostic systems
Electron energy
Emission analysis
Fourier transform spectrometers
Fourier transforms
High aspect ratio
Higher harmonics
Low aspect ratio
Plasmas
Temperature
Thomson scattering
Tokamak devices
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Summary:Wendelstein 7-X stellarator has a high aspect ratio which makes the electron cyclotron harmonics spectrally well separated and more straightforward to interpret compared to a tokamak with a low aspect ratio. For fusion reactor relevant plasma operations, Wendelstein 7-X is planned to operate at high plasma densities. For these plasma conditions, the classical electron cyclotron emission fails as a diagnostic tool for electron temperature because optically thick O1 and X2 mode are in cut-off. In this paper, we report on the radiation temperatures of X-mode electron cyclotron emission measured with Fourier transform spectrometer from the high-density plasmas. The radiation temperatures of X2 and X3 mode are compared to electron temperature measured with Thomson scattering diagnostic. This comparison suggests that X3-mode can be used as a diagnostic tool to provide electron temperature for high-density plasmas beyond the cut-off of X2-mode.
ISSN:1748-0221
1748-0221
DOI:10.1088/1748-0221/15/09/P09024