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Magnetic-surface quality in nonaxisymmetric plasma equilibria
Carolin Nührenberg1, Allen H Boozer, Stuart R Hudson
1Max-Planck-Institut für Plamaphysik, IPP-Euratom Association, Teilinstitut Greifswald, 17491 Greifswald, Germany. Carolin.Nuehrenberg@ipp.mpg.de
Physical Review Letters
|August 8, 2009
Summary
Nonaxisymmetric magnetic field shaping can disrupt plasma confinement by breaking magnetic surfaces. A new perturbation method efficiently identifies this drive for islands in stellarator equilibria.
Area of Science:
- Plasma physics
- Fusion energy research
- Magnetohydrodynamics
Background:
- Magnetic confinement fusion relies on stable magnetic surfaces to contain high-temperature plasmas.
- Nonaxisymmetric magnetic field shaping, while offering potential advantages, can introduce instabilities.
- The breakup of magnetic surfaces is a critical failure mode that degrades plasma confinement.
Purpose of the Study:
- To investigate the mechanisms by which nonaxisymmetric magnetic shaping degrades plasma confinement.
- To develop and apply an efficient method for quantifying the drive for magnetic island formation.
- To analyze the impact of shaping-induced effects on stellarator magnetic equilibria.
Main Methods:
- Development of an efficient perturbation method to calculate the drive for magnetic islands.
- Application of this method to analyze magnetic island formation in stellarator equilibria.
- Numerical analysis of magnetic surface breakup due to intrinsic shaping effects.
Main Results:
- The study identified specific intrinsic shaping effects that drive the breakup of magnetic surfaces.
- The developed perturbation method proved efficient in determining the magnitude of this drive.
- Analysis of stellarator equilibria revealed the conditions under which magnetic islands form and degrade confinement.
Conclusions:
- Nonaxisymmetric shaping introduces intrinsic effects that can lead to magnetic surface breakup and plasma confinement loss.
- The efficient perturbation method provides a valuable tool for assessing and mitigating these instabilities in stellarator designs.
- Understanding and controlling magnetic island formation is crucial for achieving stable and efficient magnetic confinement fusion.
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