COMPLETE SUPPRESSION OF THE M/N = 2/1 NEOCLASSICAL TEARING MODE USING RADIALLY LOCALIZED ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D AND THE REQUIREMENTS FOR ITER
A271 COMPLETE SUPPRESSION OF THE M/N = 2/1 NEOCLASSICAL TEARING MODE USING RADIALLY LOCALIZED ELECTRON CYCLOTRON CURRENT DRIVE ON DIII-D AND THE REQUIREMENTS FOR ITER. DIII-D experiments demonstrate the first real-time feedback control of the relative location of a narrow beam of microwaves to completely suppress and eliminate a growing tearing mode at the q = 2 surface. long wavelength tearing modes such as the m/n = 2/1 instability are particularly deleterious to tokamak operation. Confinement is seriously degraded by the island, plasma rotation can cease (mode-lock) and disruption can occur. The neoclassical tearing mode (NTM) becomes unstable due to the presence of a helically-perturbed bootstrap current and can be stabilized by replacing the missing bootstrap current in the island O-point by precisely located co-electron cyclotron current drive (ECCD). The optimum position is found when the DIII-D plasma control system (PCS) is put into a search and suppress mode that makes small radial shifts (in about 1 cm steps) in the ECCD location based on minimizing the Mirnov amplitude. Requirements for ITER are addressed.
- Research Organization:
- GENERAL ATOMICS (US)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- AC03-99ER54463
- OSTI ID:
- 814031
- Country of Publication:
- United States
- Language:
- English
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