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X-Point-Position-Dependent Intrinsic Toroidal Rotation in the Edge of the TCV Tokamak
T Stoltzfus-Dueck1, A N Karpushov2, O Sauter2
1Princeton University, Princeton, New Jersey 08544, USA.
Physical Review Letters
|July 22, 2015
Summary
Edge rotation in Tokamak à Configuration Variable decreases with increasing X point radial position. This impacts core rotation, demonstrating a rigid shift and affecting central rotation speeds significantly.
Area of Science:
- Plasma physics
- Fusion energy research
Background:
- Understanding plasma rotation is crucial for magnetic confinement fusion.
- Edge localized modes and magnetic field configurations influence plasma behavior.
Purpose of the Study:
- Investigate the impact of the X point's major radial position on edge intrinsic rotation.
- Analyze the relationship between edge and core plasma rotation.
- Examine the effect of magnetic field gradient (∇B) direction on rotation.
Main Methods:
- Conducted experiments on Tokamak à Configuration Variable using Ohmic L-mode discharges.
- Varied the major radial position of the X point, R(X).
- Measured edge and core rotation profiles.
Main Results:
- Edge rotation decreased linearly as R(X) increased.
- Rotation vanished or became countercurrent for outboard X points, matching theory.
- Core rotation shifted rigidly with edge rotation, altering central speeds by over 100%.
- Core rotation reversals had minimal impact on edge rotation.
- Edge rotation was more countercurrent in unfavorable ∇B configurations.
Conclusions:
- The X point position is a key factor controlling edge intrinsic rotation in tokamaks.
- A strong coupling exists between edge and core plasma rotation.
- Results support theoretical models of plasma rotation dynamics.
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