Demonstration of Effective Control of Fast-Ion-Stabilized Sawteeth by Electron-Cyclotron Current Drive
Abstract
In a tokamak plasma, sawtooth oscillations in the central temperature, caused by a magnetohydrodynamic instability, can be partially stabilized by fast ions. The resulting less frequent sawtooth crashes can trigger unwanted magnetohydrodynamic activity. This Letter reports on experiments showing that modest electron-cyclotron current drive power, with the deposition positioned by feedback control of the injection angle, can reliably shorten the sawtooth period in the presence of ions with energies ≥0.5MeV. Certain surprising elements of the results are evaluated qualitatively in terms of existing theory.
- Publication:
-
Physical Review Letters
- Pub Date:
- March 2009
- DOI:
- 10.1103/PhysRevLett.102.115004
- Bibcode:
- 2009PhRvL.102k5004L
- Keywords:
-
- 52.35.Py;
- 52.50.Sw;
- 52.55.Fa;
- 52.55.Pi;
- Macroinstabilities;
- Plasma heating by microwaves;
- ECR LH collisional heating;
- Tokamaks spherical tokamaks;
- Fusion products effects fast particle effects