Numerical simulation of Tokamak plasma equilibrium evolution
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This contribution focuses on the numerical methods recently developed in order to sim- ulate the time evolution of a Tokamak plasma equilibrium at the resistive diffusion time scale. We develop on the method proposed by [1] for the coupling of magnetic equilibrium and current diffusion. We introduce a new space discretization for the poloidal flux using C 0 and C 1 finite ele- ments [2]. This, together with the use of spline functions to represent the diamagnetic function in the resistive diffusion equation, enables to restrain numerical oscillations which can occur with the original method. We add to the model an evolution equation for electron temperature in the plasma. This enables us to compute consistently the plasma resistivity and the non-inductive current terms called bootstrap current needed in the resistive diffusion equation. It also enables us to evolve the pressure term in the simulation. These numerical methods are implemented in the plasma equilibrium code NICE. The code is coupled with a magnetic feedback controller through the MUSCLE3 library [3]. This enables to simulate a prescribed plasma scenario. The results for an X-point forma- tion scenario in the WEST tokamak are presented as a first illustration of the efficiency of the developed numerical methods.
