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Nonambipolar transport by trapped particles in tokamaks
Jong-Kyu Park1, Allen H Boozer, Jonathan E Menard
1Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
Physical Review Letters
|March 5, 2009
Summary
Small magnetic field changes in tokamaks can disrupt performance via nonambipolar transport. This study resolves discrepancies between theory and experiment using a generalized analytic treatment, improving fusion energy predictions.
Area of Science:
- Plasma Physics
- Fusion Energy
- Magnetic Confinement Fusion
Background:
- Nonaxisymmetric magnetic field perturbations significantly impact tokamak performance by inducing nonambipolar transport.
- Existing theories predicting these effects have shown inconsistencies with experimental tokamak observations.
Purpose of the Study:
- To resolve the discrepancy between theoretical predictions and experimental observations of nonambipolar transport in tokamaks.
- To provide a generalized analytic treatment for understanding the impact of magnetic field nonaxisymmetries.
Main Methods:
- Developed a generalized analytic treatment for nonambipolar transport in tokamaks.
- Incorporated the effects of resonant trapped particles and nonaxisymmetric field variations along perturbed field lines.
Main Results:
- The generalized analytic treatment significantly reduces the discrepancy between theoretical predictions and experimental data.
- Identified two key effects: resonance of bounce and precession rates in trapped particles and field strength variation along perturbed field lines.
Conclusions:
- The refined theory better explains experimental observations of nonambipolar transport in tokamaks.
- The findings are crucial for optimizing the performance of current and future fusion devices like the International Thermonuclear Experimental Reactor (ITER).
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