Radial electric fields and global electrostatic micro-instabilities in tokamaks and stellarators
There is mounting theoretical and experimental evidence that radial electric fields play a pivotal role in the dynamics of turbulence responsible for anomalous transport in tokamaks. In this paper, the effects of these radial electric fields on various electrostatic modes are investigated with a full radius gyrokinetic formulation that unifies the axisymmetric tokamak and helial stellarator perspectives. In particular, it is shown that the shearing rate criterion for stabilization established for tokamaks can be generalized to helial configurations. In addition, another stabilizing mechanism independent of the shearing rate has been found for the cases of toroidal and helial ion temperature gradient (ITG) modes. On the other hand, it is shown that the inclusion of trapped particle (ion and electron) dynamics can have strong consequences: in some cases the presence of radial electric fields is destabilizing rather than stabilizing.
Bibliographic Reference: An article published as an internal report: LRP 711/01, 20 pp.
ISBN: ISSN 0458-5895
Record Number: 200114100 / Last updated on: 2001-11-28
Original language: en
Available languages: en