Intermittent Transport Associated with the Geodesic Acoustic Mode near the Critical Gradient Regime

Journal Article · Fri Oct 05 04:00:00 EDT 2007 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.99.145003· OSTI ID:21024239

Miki, K; Kishimoto, Y; Li, J Q ^[1]; Miyato, N ^[2]

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1. Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011 (Japan)
2. Fusion Research and Development Directorate, JAEA, Naka, Ibaraki 311-0193 (Japan)

Turbulent transport near the critical gradient in toroidal plasmas is studied based on global Landau-fluid simulations and an extended predator-prey theoretical model of ion temperature gradient turbulence. A new type of intermittent transport associated with the emission and propagation of a geodesic acoustic mode (GAM) is found near the critical gradient regime, which is referred to as GAM intermittency. The intermittency is characterized by new time scales of trigger, damping, and recursion due to GAM damping. During the recursion of intermittent bursts, stationary zonal flow increases with a slow time scale due to the accumulation of undamped residues and eventually quenches the turbulence, suggesting that a nonlinear upshift of the critical gradient, i.e., Dimits shift, is established through such a dynamical process.

• OSTI ID: 21024239
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 14 Vol. 99; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHARGE TRANSPORT
ION TEMPERATURE
NONLINEAR PROBLEMS
PLASMA
SIMULATION
TEMPERATURE GRADIENTS
TURBULENCE