Microturbulent drift mode stability before internal transport barrier formation in the Alcator C-Mod radio frequency heated H-mode

Journal Article · Fri Jul 15 00:00:00 EDT 2005 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.1947795· OSTI ID:20764407

Redi, M H; Dorland, W; Fiore, C L; Baumgaertel, J A; Belli, E M; Hahm, T S; Hammett, G W; Rewoldt, G ^[1]

---

1. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

H-mode experiments on Alcator C-Mod [I. H. Hutchinson, R. L. Boivin, F. Bombarda et al., Phys. Plasmas 1, 1511 (1994)], which exhibit an internal transport barrier (ITB), have been examined with gyrokinetic calculations, before barrier formation. Ion temperature gradient (ITG) and electron temperature gradient (ETG) modes are unstable outside the barrier region and not strongly growing in the core; in the barrier region ITG is only weakly unstable. Linear calculations support the picture that ITG and ETG modes drive high transport outside the ITB, and that weakly unstable ITG modes in the barrier region correlate with reduced particle transport and improved thermal confinement even before the ITB is established, without the need for ExB shear stabilization. Long-wavelength mode stability in the barrier region is analyzed in the context of a phase diagram for ion and electron drift waves by varying the temperature and density scale lengths. Results from the gyrokinetic code GS2 [M. Kotschenreuther, G. Rewoldt, W. M. Tang et al., Comput. Phys. Commun. 88, 128 (1995)] are compared to standard threshold models and benchmark successfully against the experiment in the plasma core.

• OSTI ID: 20764407
• Journal Information: Physics of Plasmas, Vol. 12, Issue 7; Other Information: DOI: 10.1063/1.1947795; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALCATOR DEVICE
BENCHMARKS
CHARGED-PARTICLE TRANSPORT
DRIFT INSTABILITY
ELECTROMAGNETIC FIELDS
ELECTRON DRIFT
ELECTRON TEMPERATURE
H-MODE PLASMA CONFINEMENT
ION TEMPERATURE
PHASE DIAGRAMS
PLASMA
PLASMA DENSITY
PLASMA DRIFT
PLASMA SIMULATION
RADIOWAVE RADIATION
RF SYSTEMS
STABILIZATION
TEMPERATURE GRADIENTS
THERMAL BARRIERS
TURBULENCE