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Density fluctuation measurements using beam emission spectroscopy on Heliotron J
1Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan. kobayashi@iae.kyoto-u.ac.jp
The Review of Scientific Instruments
|November 7, 2012
Summary
Researchers measured plasma density fluctuations in Heliotron J using beam emission spectroscopy. The study identified distinct radial structures for three fast-ion-driven magnetohydrodynamic instability modes.
Area of Science:
- Plasma physics
- Fusion energy research
- Spectroscopy
Background:
- Heliotron J features a complex non-symmetrical helical-magnetic-axis configuration.
- Understanding plasma density fluctuations is crucial for fusion energy development.
- Beam emission spectroscopy (BES) is a key diagnostic for plasma measurements.
Purpose of the Study:
- To measure density fluctuations in Heliotron J using BES.
- To optimize diagnostic sightlines for accurate spatial resolution.
- To investigate the radial structure of density fluctuations associated with instabilities.
Main Methods:
- Utilized beam emission spectroscopy (BES) with a tangential neutral beam.
- Performed numerical calculations to determine optimal sightlines and spatial resolution (Δρ < ± 0.07).
- Modified interference filters and detection systems for radial profile measurements.
Main Results:
- Successfully measured the radial profile of density fluctuations across the plasma region.
- Identified three coherent modes linked to fast-ion-driven magnetohydrodynamic instabilities.
- Observed distinct radial structures for each of the three instability modes.
Conclusions:
- Beam emission spectroscopy is effective for diagnosing density fluctuations in Heliotron J.
- The study revealed specific radial characteristics of fast-ion-driven MHD instabilities.
- Optimized diagnostic setup enables detailed investigation of plasma turbulence and instabilities.
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