Numerical analysis for the free-boundary current reversal equilibrium in the AC plasma current operation in Tokamak

Abstract Abstract In the last decades, tokamak discharges with zero total toroidal current have been reported in tokamak experiments, which is one of the most key problems in the AC operations. An efficient free-boundary equilibrium code is developed to investigate such advanced tokamak discharges with current reversal equilibrium configuration. The calculation results show that the reversal current equilibrium can maintain finite pressure, extreme high \beta_{p}, and also have considerable effects on the position of the X-point, magnetic separatrix shape, and hence the position of the strike point on the divertor plates, which is extremely useful for the magnetic design, the MHD stability analysis, and the experimental data analysis etc. for the AC plasma current operation on tokamaks.