Real-time identification of the current density profile in the JET Tokamak: method and validation

Didier Mazon (1) , Jacques Blum (2) , Cédric Boulbe (2) , Blaise Faugeras (2) , A. Boboc (3) , M. Brix (3) , P. de Vries (3) , S. Sharapov (3) , L. Zabeo (3)

1 DRFC - Département de Recherche sur la Fusion Contrôlée
2 JAD - Laboratoire Jean Alexandre Dieudonné
3 Euratom/UKAEA Fusion Assoc.

The real-time reconstruction of the plasma magnetic equilibrium in a Tokamak is a key point to access high performance regimes. Indeed, the shape of the plasma current density profile is a direct output of the reconstruction and has a leading effect for reaching a steady-state high performance regime of operation. In this paper we present the methodology followed to identify numerically the plasma current density in a Tokamak and its equilibrium. In order to meet the real-time requirements a C++ software has been developed using the combination of a finite element method, a nonlinear fixed point algorithm associated to a least square optimization procedure. The experimental measurements that enable the identification are the magnetics on the vacuum vessel, the interferometric and polarimetric measurements on several chords and the motional Stark effect. Details are given about the validation of the reconstruction on the JET tokamak, either by comparison with 'off-line' equilibrium codes or real time software computing global quantities.

Mots clés: Tokamak; Grad Shafranov; JET; inverse problem; plasma equilibrium; real time

Domaines: Analyse numérique [math.NA]; Physique des plasmas [physics.plasm-ph]

Didier Mazon, Jacques Blum, Cédric Boulbe, Blaise Faugeras, A. Boboc, et al.. Real-time identification of the current density profile in the JET Tokamak: method and validation. 48th IEEE Conference, Dec 2009, China. pp.285-290, ⟨10.1109/CDC.2009.5399695⟩. ⟨hal-00414481⟩