Simulation technique of free-boundary equilibrium evolution in plasma ramp-up phase
We describe a new scheme for a consistent linkage between the transport and equilibrium solvers in the integrated transport code TOPICS for a transport simulation in tokamaks during a plasma volume ramp-up phase. Although the flux conserving tokamak (FCT) equilibrium solver implemented in TOPICS is well consistent with the transport solver, it cannot evaluate a toroidal magnetic flux associated with an evolving equilibrium by itself. The evolution of the equilibrium is then modeled with a combination of the determination of the toroidal magnetic flux by the iterative solution of the GradShafranov equation and the FCT scheme. The new scheme developed is applied to a predictive simulation with the volume expansion in a tokamak comparable to JT-60U for both the limiter and the divertor cases.
free-boundary equilibrium plasma ramp-up tokamak fct gradshafranov equation volume expansion