Conservation of plasma quantities during the evolution of 2D edge/SOL grid in ITER diverted plasmas

The ITER High Fidelity Plasma Simulator (HFPS), which is being developed by combining a core-edge-SOL/div transport modelling code (JINTRAC) and a free-boundary equilibrium evolution code (DINA), is currently exploring a capability of consistently modelling the edge plasma along the dynamic changes in the plasma equilibrium. This requires updates of the 2D edge/SOL grid using the free-boundary equilibria, while the 2D edge/SOL plasma solution needs to be compensated for the moving finite volume effect to conserve the plasma fluid quantity in these grid updates. Therefore, a residual is proposed as the deviation between the plasma solutions with and without consideration of the moving finite volume effect. At the grid update, the residual is calculated by estimating its time derivatives using the Leibniz-Reynolds transport theorem with the Runge-Kutta 2^nd order method. When the 2D edge/SOL grid moves with the plasma equilibrium, the closed flux-surface boundary quantities computed from the JETTO core solver remain unchanged, while the added/removed computational domains near the SOL/vacuum boundaries are set by applying the decay-length boundary conditions. The implemented scheme has been applied to ITER diverted plasmas and the results are compared with the static grid cases. The developed techniques are foreseen to conserve plasma quantities along the evolution of the plasma equilibrium, therefore enabling a self-consistent core-edge-SOL/div integrated plasma transport simulation of tokamak plasmas including transients such as current ramp-up/down and L-H/H-L confinement transitions. ITER Disclaimer: The views and opinions expressed herein do not necessarily reflect those of the ITER Organization.