Mean and Oscillating Plasma Flows and Turbulence Interactions across the L-H Confinement Transition

Journal Article · Fri Feb 11 04:00:00 EST 2011 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.106.065001· OSTI ID:21532299

Conway, G D; Angioni, C; Ryter, F; Sauter, P ^[1]; Vicente, J ^[2]

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1. EURATOM-Association IPP, Max-Plank-Institut fuer Plasmaphysik, D-85748, Garching (Germany)
2. Associacao Euratom-IST, Instituto de Plasmas e Fusao Nuclear, Lisboa (Portugal)

A complex interaction between turbulence driven ExB zonal flow oscillations, i.e., geodesic acoustic modes (GAMs), the turbulence, and mean equilibrium flows is observed during the low to high (L-H) plasma confinement mode transition in the ASDEX Upgrade tokamak. Below the L-H threshold at low densities a limit-cycle oscillation forms with competition between the turbulence level and the GAM flow shearing. At higher densities the cycle is diminished, while in the H mode the cycle duration becomes too short to sustain the GAM, which is replaced by large amplitude broadband flow perturbations. Initially GAM amplitude increases as the H-mode transition is approached, but is then suppressed in the H mode by enhanced mean flow shear.

• OSTI ID: 21532299
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 6 Vol. 106; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ASDEX TOKAMAK
ATTRACTORS
CLOSED PLASMA DEVICES
CONFINEMENT
DENSITY
DISTURBANCES
ELECTROMAGNETIC FIELDS
EQUILIBRIUM
H-MODE PLASMA CONFINEMENT
INTERACTIONS
LIMIT CYCLE
MAGNETIC CONFINEMENT
OSCILLATIONS
PERTURBATION THEORY
PHYSICAL PROPERTIES
PLASMA
PLASMA CONFINEMENT
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TURBULENCE