Confinement and bursty transport in a flux-driven convection model with sheared flows

Garcia, O.E., Bian, N.H., Paulsen, J.-V., Benkadda, S. and Rypdal, K. (2003) Confinement and bursty transport in a flux-driven convection model with sheared flows. Plasma Physics and Controlled Fusion, 45(6), pp. 919-932. (doi: 10.1088/0741-3335/45/6/306)

Abstract

Transport and confinement within the resistive-g paradigm are investigated by means of two-dimensional numerical simulations. The system is driven by a constant incoming heat flux at the inner radial boundary. Different confinement and transport states are identified, involving self-sustained sheared poloidal flows. At the onset of turbulent convection the probability distribution functions of pressure and radial velocity fluctuations measured in the centre of the plasma layer have a nearly Gaussian form. Further increasing the heat flux drive these distributions become increasingly non-Gaussian, developing exponential tails. This large-scale intermittency is ascribed to the presence of bursting in the domain averaged convective transport and the fluctuation energy integrals. The quasi-periodic bursts are separated by shear-dominated quiescent periods in which the mean flow energy decreases and the confined heat increases on diffusive timescales. The time-averaged thermal energy confined within the plasma layer shows a power law dependence and significant increase with the injected power over the range of turbulent convection investigated.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Bian, Dr Nicolas Horace
• Authors: Garcia, O.E., Bian, N.H., Paulsen, J.-V., Benkadda, S., and Rypdal, K.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Plasma Physics and Controlled Fusion
• ISSN: 0741-3335
• ISSN (Online): 1361-6587