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Updated: Feb 11, 2026
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3D Depth Profile Reconstruction of Segregated Impurities Using Secondary Ion Mass Spectrometry
Published on: April 29, 2020
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Effective ion charge (Zeff) measurements and impurity behavior in KSTAR
1Institute of Space Technology, P.O. Box 2750, Islamabad 44000, Pakistan.
The Review of Scientific Instruments
|May 3, 2018
Summary
A new diagnostic system measures effective charge (Zeff) in KSTAR plasma using visible bremsstrahlung. Zeff profiles shift from flat in L-mode to hollow in H-mode, consistent with spectrometer data.
Area of Science:
- Plasma Physics
- Fusion Energy Research
- Diagnostic Systems
Background:
- Understanding plasma properties like effective charge (Zeff) is crucial for fusion energy.
- Previous methods for Zeff measurement had limitations in spatial resolution or spectral interference.
Purpose of the Study:
- To develop and validate a visible bremsstrahlung detector array system for measuring Zeff profiles in KSTAR.
- To investigate the behavior of Zeff profiles during different plasma modes (L-mode vs. H-mode) and assess the impact of boronization.
Main Methods:
- Utilized a visible bremsstrahlung detector array with interference filters and photomultiplier tubes.
- Employed Abel inversion techniques to obtain radial emissivity from line-averaged measurements.
- Cross-validated Zeff measurements with a visible spectrometer and incorporated X-ray imaging crystal spectrometry data.
Main Results:
- Successfully measured Zeff profiles across the entire minor radius, free from spectral line interference.
- Observed flat Zeff profiles in L-mode plasmas and hollow profiles in H-mode plasmas.
- Demonstrated consistency between bremsstrahlung-derived Zeff and spectrometer measurements, and evaluated the effect of boronization on Zeff.
Conclusions:
- The developed visible bremsstrahlung diagnostic system is effective for Zeff profile determination in KSTAR.
- The study provides insights into plasma confinement regimes and operational effects like boronization on effective charge.
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