Investigation of multiple-ion-source neutral beam operation conditions compatible with motional Stark effect diagnostics

The motional Stark effect (MSE) diagnostic system at KSTAR (Korea Superconducting Tokamak Advanced Research) often suffers from the drawback of possible systematic uncertainties in measurements due to overlap of the MSE spectra generated from three different ion sources that constitute a single neut...

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Bibliographic Details
Published in:Review of scientific instruments 2022-08, Vol.93 (8), p.083503-083503
Main Author: Ko, Jinseok
Format: Article
Language:English
Subjects:
Bandpass filters
Beam injection
Diagnostic systems
Ion sources
Neutral beams
Pitch (inclination)
Scientific apparatus & instruments
Stark effect
Vector analysis
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Summary:The motional Stark effect (MSE) diagnostic system at KSTAR (Korea Superconducting Tokamak Advanced Research) often suffers from the drawback of possible systematic uncertainties in measurements due to overlap of the MSE spectra generated from three different ion sources that constitute a single neutral beam injection system. In particular, one ion source injected in the most tangential direction always causes strong spectral overlaps which, therefore, imposes regulations and constraints on the energy combination among the ion sources. A Stokes-vector analysis has been performed to produce operation windows for the energy combination between the ion source used in the MSE measurement and the ion source with the largest tangential injection angle. The analysis includes various practical factors, such as the distortion of the transmission function of bandpass filters and pitch angle profiles collected from a vast amount of KSTAR discharges. The two-dimensional parameter space, or the contour plot, on the expected systematic offsets in the measured pitch angle has been generated from this analysis, which can serve as a quantitative guideline for operating the multiple-ion-source neutral beam heating system.
ISSN:0034-6748
1089-7623
DOI:10.1063/5.0101482