Behn, R.

Ivanov, A.A.

Khayrutdinov, R.R.

Medvedev, S.Yu.

Poshekhonov, Yu.Yu.

Sauter, O.

Villard, L.

Infoscience - École polytechnique fédérale de Lausanne

Reconstruction of Tokamak Equilibria with Pedestal Profiles Using theSPIDER CodeA.A.Ivanov1, S.Yu.Medvedev1, Yu.Yu.Poshekhonov1,R.Behn2, O.Sauter2, L.Villard2 and R.R.Khayrutdinov31Keldysh Institute, Russian Academy of Sciences, Moscow, Russia2CRPP, Association Euratom-Confédération Suisse, EPFL, Lausanne, Switzerland3TRINITI, Moscow Region, RussiaEquilibrium reconstruction codes are the main tools for the interpretation of experimentaldata in modern tokamaks. In case of non-monotonic reversed shear or "skin" profiles at the edge,the standard reconstruction methods [1, 2] do not perform satisfactorily and plasma boundaryshape and profiles are not determined accurately. In particular, the pedestal profile measure-ments rely upon the magnetic surface mapping onto the real space that should be determinedself-consistently using the reconstructed free-boundary equilibrium.To avoid the restrictions of the previous generation of codes and to improve accuracy andefficiency of equilibrium reconstruction, a new adaptive grid plasma equilibrium reconstruc-tion solver in the frame of the SPIDER [3] code has been developed. The automatic mappingof the magnetic surfaces provided by the adaptive grid code allows for accurate resolution ofthe pedestal region while using the same flux grid in the plasma for efficient free-boundaryequilibrium calculations.The changes in the mapping of magnetic surfaces due to the presence of pedestals are es-timated for fixed and free boundary equilibrium reconstructions of ELMy TCV shots. Usingthe measured temperature and density profiles, the current density profile is reconstructed andthe influence of the bootstrap current in the pedestal is investigated. The results can be cross-checked using the SPIDER code operating in the rectangular grid mode for the free boundarycalculations.The application of the developed methods to configurations with large fraction of noninduc-tive current, like in the TCV shots with high bootstrap current fraction, is discussed.[1] L.L.Lao et al. Nucl. Fusion 30, 1035 (1990)[2] F.Hofmann, S.C.Jardin, Nucl. Fusion 30, 2013 (1990)[3] A.A.Ivanov et al., 32nd EPS Conf. on Plasma Phys., ECA Vol.29C, P-5.063 (2005)Acknowledgements The CRPP authors are supported in part by the Swiss National Science Foundation.

Reconstruction of Tokamak Equilibria with Pedestal Profiles Using the SPIDER Code

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Reconstruction of Tokamak Equilibria with Pedestal Profiles Using the SPIDER Code

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