The equilibrium and time evolution of the parameters of the Tokamak de Varennes

The equilibrium and time evolution of the density, current, and temperature profiles for a tokamak are numerically analyzed using the one-dimensional transport code VARTOK1. The numerical model contains the full neoclassical transport, with coefficients covering transitions between regimes, and includes the Ware pinch and bootstrap currents, empirical anomalous particle and electron heat transports based on Alcator scaling, neutral particle transport, oxygen impurity, and diffusion of the poloidal magnetic field. The solution uses a time- and space-centered Crank–Nicolson scheme. The equilibrium profiles are first determined for a constant current of 200 kA by running the code at constant current. Then the current is ramped down to zero in 20 ms, and the time evolution of the different parameters are followed.