Control of bootstrap current in the pedestal region of tokamaks

Journal Article · Sun Dec 15 00:00:00 EST 2013 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4843895· OSTI ID:22218343

Shaing, K. C. ^[1]; Lai, A. L. ^[1]

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1. Institute for Space and Plasma Sciences, National Cheng Kung University, Tainan City 70101, Taiwan (China)

The high confinement mode (H-mode) plasmas in the pedestal region of tokamaks are characterized by steep gradient of the radial electric field, and sonic poloidal U{sub p,m} flow that consists of poloidal components of the E×B flow and the plasma flow velocity that is parallel to the magnetic field B. Here, E is the electric field. The bootstrap current that is important for the equilibrium, and stability of the pedestal of H-mode plasmas is shown to have an expression different from that in the conventional theory. In the limit where ‖U{sub p,m}‖≫ 1, the bootstrap current is driven by the electron temperature gradient and inductive electric field fundamentally different from that in the conventional theory. The bootstrap current in the pedestal region can be controlled through manipulating U{sub p,m} and the gradient of the radial electric. This, in turn, can control plasma stability such as edge-localized modes. Quantitative evaluations of various coefficients are shown to illustrate that the bootstrap current remains finite when ‖U{sub p,m}‖ approaches infinite and to provide indications how to control the bootstrap current. Approximate analytic expressions for viscous coefficients that join results in the banana and plateau-Pfirsch-Schluter regimes are presented to facilitate bootstrap and neoclassical transport simulations in the pedestal region.

• OSTI ID: 22218343
• Journal Information: Physics of Plasmas, Vol. 20, Issue 12; Other Information: (c) 2013 AIP Publishing LLC; 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
APPROXIMATIONS
BANANA REGIME
BOOTSTRAP CURRENT
BOUNDARY LAYERS
EDGE LOCALIZED MODES
ELECTRIC FIELDS
ELECTRON TEMPERATURE
H-MODE PLASMA CONFINEMENT
ION TEMPERATURE
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
NEOCLASSICAL TRANSPORT THEORY
PFIRSCH-SCHLUETER REGIME
PLASMA
PLASMA SIMULATION
TEMPERATURE GRADIENTS
TOKAMAK DEVICES
VISCOSITY