Plasma Position Control and Current Profile Reconstruction for Tokamaks
F.Saint-Laurent*, P.H.Moreau, S.P.Bremond (EURATOM-CEA) B.Faugeras, C.Boulbe, J.Blum (Université de Nice Sophia-Antipolis)
In the field of fusion reactor studies, the Tore Supra tokamak explores the way of high-power long-duration plasma discharges. When operating such discharges, the first wall, located inside the vacuum vessel in front of the plasma, must sustain the heat flux up to 10 MW/m2, released by the high temperature plasma following both convection and radiation processes. Real-time identification and control of the plasma boundary are thus mandatory to safely operate the device. The best way is to solve the 2D Grad-Shafranov equation which describes the axisymmetric plasma equilibrium and thus to identify the non-linear source of plasma current. The fast solver EQUINOX using finite element method and fixed-point algorithm was developed and implemented since 2003. Boundary conditions were imposed using external magnetic measurements only. For advanced plasma regimes (high confinement regime) the current profile must be controlled and thus real-time determined. As magnetics are no longer sufficient to constraint the solution, information provided by other diagnostics were included and tested as additional constraints. Some examples of the resulting current profile improvement will be given