CASTOR stands for the “Control of PlAsma inSTability, Optimization and model Reduction”. CASTOR focuses on the development of innovative numerical tools to improve the modeling and control of complex plasma flows, governed by the equations of magnetohydrodynamics (MHD). The two main applications addressed in CASTOR are magnetic fusion plasmas and astrophysical plasmas, where MHD models can be used to describe turbulent transport and instabilities yielding transitions between equilibrium states. The objectives are to develop methods enabling real-time control of MHD flows and optimization of plasma
discharge scenarios in tokamaks.
Castor is a common project between Inria, Université Côte d’Azur and CNRS through the Laboratoire Jean-Alexandre Dieudonné (LJAD). It gathers researchers from the PDE and Numerical Analysis group and the Numerical Modeling and Fluid Dynamics group of LJAD.
The models we consider possess different levels of complexity, ranging from single-fluid, incompressible to multi-component, compressible models. The main applications addressed in CASTOR are magnetic fusion plasmas and astrophysical plasmas, where MHD models can be used to describe turbulent transport and instabilities yielding transitions between equilibrium states. In both cases, adjoint methods as a tool to optimize or control the model outputs will be developed together with reduced models for a faster response, enabling real-time control of these flows and optimization of plasma discharge scenarios in tokamaks.”
The modeling of nuclear fusion plasmas in tokamaks relies heavily on magnetohydrodynamics (MHD), which treats the plasma as a conductive fluid influenced by magnetic fields. This framework has been crucial in predicting plasma behavior, particularly for understanding macroscopic instabilities such as kink modes, tearing modes, and edge-localized modes (ELMs). Current challenges in controlling these instabilities include the difficulty in predicting their onset conditions in realistic operational scenarios, or limitations in
real-time response systems for instability mitigation. These challenges are central to international fusion projects like ITER, where maintaining plasma stability remains a critical hurdle to achieving sustainable fusion energy.
Computational Fluid Dynamics
The modeling of nuclear fusion plasmas in tokamaks relies heavily on magnetohydrodynamics, which treats the plasma as an electrically conducting fluid responding to magnetic fields. This framework has been crucial in predicting plasma behavior in tokamaks, particularly for understanding macroscopic instabilities such as kink modes, tearing modes, and edge-localized modes (ELMs). Current challenges in controlling these instabilities include the difficulty in predicting their onset conditions in realistic operational scenarios, or limitations in real-time response systems for instability mitigation. These challenges are central to international fusion projects like ITER, where maintaining plasma stability remains a critical hurdle to achieving sustainable fusion energy.
Modeling of turbulent flows
The modeling of nuclear fusion plasmas in tokamaks relies heavily on magnetohydrodynamics (MHD), which treats the plasma as a conductive fluid influenced by magnetic fields. This framework has been crucial in predicting plasma behavior, particularly for understanding macroscopic instabilities such as kink modes, tearing modes, and edge-localized modes (ELMs). Current challenges in controlling these instabilities include the difficulty in predicting their onset conditions in realistic operational scenarios, or limitations in real-time response systems for instability mitigation. These challenges are central to international fusion projects like ITER, where maintaining plasma stability remains a critical hurdle to achieving sustainable fusion energy.
Magnetohydrodynamics
Magnetohydrodynamics (MHD) couples Maxwell’s equations of electromagnetism with hydrodynamics to describe the macroscopic behavior of conducting fluids such as plasmas. It plays a crucial role in strophysics, planetary magnetism, engineering and controlled nuclear fusion. The study of fluid dynamics is of key relevance for the simulation of environmental systems, including atmospheric and oceanic flows.
CASTOR investigates magnetohydrodynamic (MHD) instabilities in stellar plasmas, focusing on nonlinear (subcritical) transitions. We develop the conditions that trigger instabilities in stellar interiors and discs without imposing symmetries or making prior assumptions about physical processes. This research will be conducted through the ERC project CIRCE (2024-2029), developing numerical methods to identify “minimal seeds” (least-energy perturbations) that can nonlinearly trigger transitions between stable states in stellar objects. The team
is developing Tcheby-CUBE, a new software to simulate three-dimensional flows with magnetic fields specifically for stellar applications. A key focus is the dynamo effect, where turbulent motions of electrically
conducting fluids convert kinetic energy into electromagnetic energy. They plan to characterize the amplification and saturation mechanisms of these instabilities, quantify associated transport of chemical elements and angular momentum, and improve parametrization of magnetically-driven transport in stellar evolution codes. This work will help understand stellar rotation, accretion rates, and magnetic field
maintenance despite energy dissipation.
CASTOR develops numerical methods and software simulate a wide range of MHD instabilities in tokamaks, to help with the design of instability control or mitigation systems, to produce scenarios for the evolution of the voltages in the poloidal field coils, to control the plasma shape in time, and to perform equilibrium reconstruction from sparse experimental measurements. For more details on the research activities and projects of the team, please refer to the personal webpages and to the team annual report. Do not hesitate to contact us for scientific collaborations and/or training periods within the team.
