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Perturbed Ion Temperature and Toroidal Flow Profile Measurements in Rotating Neoclassical Tearing Mode Magnetic
L Bardóczi1,2, A Dudkovskaia3, R J La Haye1
1General Atomics, Post Office Box 85608, San Diego, California 92186-5608, USA.
Physical Review Letters
|February 23, 2024
Summary
Researchers measured ion temperature and flow in tokamak magnetic islands for the first time. These findings confirm theoretical predictions, aiding future fusion reactor designs like ITER.
Area of Science:
- Plasma physics
- Fusion energy research
- Tokamak diagnostics
Background:
- Neoclassical tearing modes (NTM) are a significant concern in tokamak fusion devices, potentially degrading plasma confinement.
- Understanding the plasma response within magnetic islands is crucial for controlling NTMs and achieving stable fusion conditions.
Purpose of the Study:
- To experimentally measure perturbed ion temperature and toroidal flow profiles within rotating neoclassical tearing modes (NTM) in a tokamak.
- To validate theoretical models and drift-kinetic simulations of plasma behavior inside magnetic islands.
- To provide data necessary for predicting the NTM onset threshold scaling for future devices like ITER.
Main Methods:
- Utilized impurity ion spectroscopy to obtain toroidally and radially resolved measurements.
- Focused on a 2,1 NTM in the DIII-D tokamak.
- Compared experimental results with drift-kinetic simulations.
Main Results:
- Observed a flat electron temperature profile across the magnetic island O point.
- Confirmed restoration of the ion temperature gradient in the presence of fast ions.
- Measured perturbed toroidal flow with minima at O points and maxima at X points of the magnetic island.
Conclusions:
- First experimental confirmation of theoretically predicted ion temperature and flow responses to magnetic islands.
- Measurements align with drift-kinetic simulation predictions.
- Crucial data for improving NTM onset threshold predictions for ITER and other future tokamaks.
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