Description
For future tokamaks and present-day operations, accurate design of discharge trajectories and actuator schemes, supported by closed-loop simulations, is essential. Fast and reliable tools are needed to reproduce plasma equilibrium and profile evolution for discharge optimization, and control-system validation. Pulse Design Tools (PDT) meet these needs by optimizing plasma and actuator trajectories and coupling discharge evolution with feedback controllers to assess tokamak operational stability.
PDT employ a combination of free-boundary and transport codes. Static free-boundary equilibrium solvers are used to optimize external conductor currents, while evolutive solvers are used to simulate controller reactions. Fast transport solvers are used to provide self-consistent plasma profile evolution for the equilibrium calculations.
In this work, we present a coupling between the free-boundary equilibrium codes (both static and evolutive) implemented in MEQ [1, 2] and the fast transport solver METIS [3]. The numerical stability of the coupled framework is evaluated using a simulated COMPASS Upgrade [4, 5] database. Discharge simulations with and without the coupling are compared, demonstrating the robustness of the approach and paving the way for future scenario preparation for COMPASS Upgrade and other tokamaks.
[1] F Hofmann. In: Computer Physics Communications 48.2 (Feb. 1988), pp. 207–221.
[2] F. Carpanese. PhD thesis. Lausanne: EPFL, 2021, p. 238.
[3] J. Artaud et al. In: Nuclear Fusion 58 (July 2018), p. 105001.
[4] R. Panek et al. In: Fusion Engineering and Design 123 (2017), pp. 1116.
[5] P. Vondracek et al. In: Fusion Engineering and Design 169 (2021), p. 112490.