Equilibrium Analysis of Tokamak Plasma Including the Eddy Current Effects in TOKASTAR-2

The equilibrium analysis including the eddy current effect was performed for TOKASTAR-2 tokamak plasma by using TOSCA code that treated the vacuum vessel as the 2D axisymmetric model. In measurement of the vacuum magnetic field without plasma, it was found that the measured magnetic field and the calculated one using the model configuration which was based on the TOKASTAR-2 design did not agree. To improve the model, some parameters in the model (e.g. coil positions) were adjusted to minimize the difference between the calculated field and the measured one. In the equilibrium analysis, the poloidal beta beta(P) and the plasma internal inductance l(i)i were determined minimizing the difference between the calculated field and the measured one for external probes. It was found that the solution calculated by the external measurement was roughly consistent with the internal field measurement, with difference in the plasma internal inductance of 0.10. The high-speed camera and the internal measurement results indicated that the shape and position of the plasma also have small errors. More improvement in the wall model would be needed to resolve these discrepancies. (C) 2020 The Japan Society of Plasma Science and Nuclear Fusion Research.