ISSN:
1089-7666
Source:
AIP Digital Archive
Topics:
Physics
Notes:
When the Mach number Mp of the poloidal rotation in a tokamak approaches unity, the poloidal variations of plasma density and potential appear to have the characteristics of a shock whose front lies on a plane (ribbon) of a fixed poloidal angle η0. The shock first appears, when 1−Mp(approximately-less-than)(ε)1/2 (ε is the inverse aspect ratio), on the inside of the torus at a shock angle η0≥π if the plasma rotates counterclockwise poloidally. As Mp increases, η0 moves in the direction of the poloidal rotation. At Mp=1, η0=2π. When Mp −1(approximately-less-than)(ε)1/2, the shock angle is at η0(approximately-less-than)π. The parallel viscosity associated with the shock is collisionality independent, in contrast to the conventional neoclassical viscosity. The viscosity reaches its maximum at Mp=1, which is the barrier that must be overcome to have a poloidal supersonic flow. Strong up–down asymmetric components of poloidal variations of plasma density and potential develop at Mp (approximately-equal-to)1. In the edge region, the convective poloidal momentum transport weakens the parallel viscosity and facilitates the L–H transition.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.860290
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