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Published on: June 24, 2016
System size effects on gyrokinetic turbulence.
B F McMillan1, X Lapillonne, S Brunner
1Centre de Recherches en Physique des Plasmas, Association Euratom-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne, PPB, 1015 Lausanne, Switzerland.
Physical Review Letters
|January 15, 2011
Summary
Turbulence-driven heat transport in magnetically confined plasmas is reexamined. The finite width of the strong gradient region, not system size, reduces diffusivity in gyrokinetic simulations.
Area of Science:
- Plasma Physics
- Fusion Energy Research
- Computational Physics
Background:
- Turbulence-driven heat transport is crucial for magnetically confined plasmas.
- Previous studies showed disagreements on system size scaling.
- Geometrical approximations may have caused inconsistencies.
Purpose of the Study:
- Reexamine turbulence-driven heat transport scaling with system size.
- Resolve quantitative disagreements using independent numerical methods.
- Investigate system size effects by modifying gradient region width.
Main Methods:
- First-principles based numerical simulations.
- Application of two distinct numerical methods.
- Modification of the strong gradient region width at fixed system size.
Main Results:
- A diffusivity reduction was observed in global gyrokinetic simulations.
- This reduction is attributed to the finite width of the strong gradient region.
- Finite overall system size was found to be less influential than the gradient region width.
Conclusions:
- The finite width of the strong gradient region is the primary driver of diffusivity reduction.
- This finding clarifies previous discrepancies in turbulence scaling studies.
- Accurate modeling of the gradient region is essential for predicting plasma confinement.
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