Asymmetric radiation-induced toroidal flow and improved confinement in tokamaks

Journal Article · Sat Apr 15 00:00:00 EDT 2006 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2192509· OSTI ID:20782741

Singh, R; Kaw, P K; Rogister, A L; Tangri, V ^[1]

---

1. Institute for Plasma Research, Bhat, Gandhinager-382 428 (India)

The role of impurity radiation in influencing the toroidal flow and radial electric fields (parameters critical for determining turbulent transport) has been studied on the edge of a tokamak plasma. It is demonstrated for the first time that the impurities distributed in an asymmetric (poloidally) manner may lead to significant density and temperature perturbations on magnetic surfaces. These, in turn, interact with the {theta} dependent toroidal field variations and yield a mean divergence of the stress tensor driving strong neoclassical toroidal flows. A self-consistent theory of interplay of equilibrium, fluctuations, neoclassical flows, and E-vectorxB-vector shear rotation in a tokamak is also presented. It is shown that the resulting enhanced toroidal velocity shear on the outer radiative layers produces a stabilizing effect on the well known instabilities (which determine edge transport) such as the drift resistive ballooning mode, the drift trapped electron mode, and the ion temperature gradient mode. For various values of the radiation asymmetry parameter, investigation of the turbulent particle flux as a function of the density gradient shows that the plasma can undergo a bifurcation into a better-confined state with a peaked density.

• OSTI ID: 20782741
• Journal Information: Physics of Plasmas, Vol. 13, Issue 4; Other Information: DOI: 10.1063/1.2192509; (c) 2006 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
ASYMMETRY
BALLOONING INSTABILITY
BIFURCATION
BOUNDARY LAYERS
DENSITY
DISTURBANCES
DRIFT INSTABILITY
ELECTRIC FIELDS
ELECTRON TEMPERATURE
EQUILIBRIUM
FLUCTUATIONS
ION TEMPERATURE
MAGNETIC SURFACES
NEOCLASSICAL TRANSPORT THEORY
PLASMA
PLASMA CONFINEMENT
PLASMA DENSITY
PLASMA IMPURITIES
RADIATION TRANSPORT
ROTATION
SHEAR
STRESSES
TEMPERATURE GRADIENTS
TOKAMAK DEVICES
TRAPPED ELECTRONS
TURBULENCE