Development of magnetohydrodynamic modes during sawteeth in tokamak plasmas

Marie-Christine Firpo (1) , Wahb Ettoumi (2) , Ricardo Farengo (3) , Hugo Ferrari (3) , Pablo Luis Garcia-Martinez (3) , Agustin Lifschitz (4)

1 LPP - Laboratoire de Physique des Plasmas
2 Groupe fusion
3 Centro Atómico Bariloche [Argentine]
4 LOA - Laboratoire d'optique appliquée

A dynamical analysis applied to a reduced resistive magnetohydrodynamics model is shown to explain the chronology of the nonlinear destabilization of modes observed in tokamak sawteeth. A special emphasis is put on the nonlinear self-consistent perturbation of the axisymmetric m=n=0 mode that manifests through the q-profile evolution. For the very low fusion-relevant resistivity values, the q-profile is shown to remain almost unchanged on the early nonlinear timescale within the central tokamak region, which supports a partial reconnection scenario. Within the resistive region, indications for a local flattening or even a local reversed-shear of the q-profile are given. The impact of this ingredient in the occurrence of the sawtooth crash is discussed.

Mots clés: magnetic reconnection; plasma magnetohydrodynamics; plasma nonlinear processes; plasma toroidal confinement; sawtooth instability; Tokamak devices

Domaines: Physique des plasmas [physics.plasm-ph]

Marie-Christine Firpo, Wahb Ettoumi, Ricardo Farengo, Hugo Ferrari, Pablo Luis Garcia-Martinez, et al.. Development of magnetohydrodynamic modes during sawteeth in tokamak plasmas. Physics of Plasmas, 2013, 20 (7), pp.072305. ⟨10.1063/1.4816025⟩. ⟨hal-00846433⟩