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Abstract

The effects of applied radial electric fields on the stability of ion temperature gradient (ITG) modes and trapped particle modes are investigated with a full radius gyrokinetic formulation in both axisymmetric and helically symmetric configurations. The validity of a simplified stabilization criterion often applied to experimental analysis (the shearing rate larger than the linear growth rate) is examined for various profiles of ExB flows using an expression for the shearing rate derived for arbitrary quasisymmetric geometries [T. S. Hahm, Phys. Plasmas 4, 4074 (1997)]. The results show that the criterion holds for profiles with finite shearing rate and for toroidal, helical, and slab-like ITG modes. However, it is not always applicable for trapped particle instabilities: a case is shown for which ExB flows are destabilising. For profiles with zero shearing rate, another stabilising mechanism is found for toroidal and helical ITG modes but not for slab-like modes.

Additional information

Authors: VILLARD L, Centre de Recherches en Physique des Plasmas, Association Euratom - Confédération Suisse, École Polytechnique Fédérale de Lausanne (CH);BOTTINO A, Centre de Recherches en Physique des Plasmas, Association Euratom - Confédération Suisse, École Polytechnique Fédérale de Lausanne (CH);SAUTER O, Centre de Recherches en Physique des Plasmas, Association Euratom - Confédération Suisse, École Polytechnique Fédérale de Lausanne (CH);VACLAVIK J, Centre de Recherches en Physique des Plasmas, Association Euratom - Confédération Suisse, École Polytechnique Fédérale de Lausanne (CH)
Bibliographic Reference: An article published in: Physics of Plasmas, Volume 9, Issue 6, (June 2002), pp.2684-2691
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at: http://ojps.aip.org/journal_cgi/dbt?KEY=PHPAEN&Volume=9&Issue=6
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