Spontaneous edge E × B sheared flow development studies in the TJ-II stellarator

Author: Pedrosa M.   Hidalgo C.   Calderon E.   Alonso A.   Orozco R.   Pablos J.   Balan P.  

Publisher: Springer Publishing Company

ISSN: 0011-4626

Source: Czechoslovak Journal of Physics, Vol.55, Iss.12, 2005-12, pp. : 1579-1587

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

The influence of plasma density and edge gradients in the development of perpendicular sheared flow has been investigated in the plasma edge region of the TJ-II stellarator. It has been experimentally observed that the generation of spontaneous perpendicular sheared flow (i.e. the naturally occurring shear layer) requires a minimum plasma density or gradient. It has been found that there is a coupling between the onset of sheared flow development and an increase in the level of plasma edge turbulence; once sheared flow is fully developed the level of fluctuations and turbulent transport slightly decreases whereas edge gradients and plasma density increase. The resulting shearing rate is close to the one required to trigger a transition to improved confinement regimes with reduction of edge turbulence, showing that spontaneous sheared flows and fluctuations keep themselves near marginal stability.

Related content