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Stellarator Turbulence: Subdominant Eigenmodes and Quasilinear Modeling
M J Pueschel1, B J Faber1, J Citrin2,3
1University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Physical Review Letters
|March 12, 2016
Summary
Gyrokinetic simulations in stellarators reveal numerous unstable and stable eigenmodes. Accounting for all these modes is crucial for accurate transport modeling in stellarator geometry.
Area of Science:
- Plasma physics
- Fusion energy research
Background:
- Stellarator geometry presents complex challenges for gyrokinetic simulations.
- Numerous subdominant, near-orthogonal unstable and stable eigenmodes arise in these simulations.
Purpose of the Study:
- To present the first results based on the full eigenmode spectrum in stellarator geometry.
- To investigate the impact of multiple eigenmodes on nonlinear plasma behavior.
Main Methods:
- Performing gyrokinetic simulations in stellarator geometry.
- Analyzing the full eigenmode spectrum, including subdominant modes.
- Examining nonlinear states of ion-temperature-gradient-driven turbulence.
Main Results:
- A multitude of subdominant unstable and stable eigenmodes are active in the nonlinear state.
- Turbulent frequency spectra exhibit broadband characteristics and a nonlinear signature at electron frequencies.
- Successful quasilinear, mixing-length transport modeling is demonstrated.
Conclusions:
- Accounting for the full spectrum of unstable modes is essential for accurate stellarator transport modeling.
- The findings advance understanding of plasma turbulence and transport in complex magnetic confinement geometries.
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