Numerical modeling of plasma transport in the edge and scrape-off layer of ASDEX Upgrade plasmas subject to RMP fields

• Grant number: 25/22183-7
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: March 02, 2026
• End date: March 01, 2027
• Field of knowledge: Physical Sciences and Mathematics - Physics - Physics of Fluids, Plasma Physics and Electrical Discharge
• Principal Investigator: Gustavo Paganini Canal
• Grantee: José Roberto Fernandes Junior
• Supervisor: Dominik Brida
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Max-Planck-Institut Für Plasmaphysik, Germany
• Associated to the scholarship: 23/15063-0 - Modeling separatrix splitting and magnetic footprints in TCABR, BP.DD

Abstract

Several scientific challenges have to be overcome before nuclear fusion can become an economically viable energy source. Among these challenges, plasma instabilities known as edge localized modes (ELMs) are still a concern when thermonuclear conditions are approached. ELMs pose a threat to the development of fusion power plants because the crash of these modes releases a significant fraction of the plasma thermal energy into the plasma scrape-off layer (SOL), thus leading to unacceptably high transient heat fluxes onto the divertor plates. Experiments worldwide have demonstrated that externally applied, non-axisymmetric, resonant magnetic perturbations (RMPs) can be used to control the plasma edge stability, thus providing a way to trigger ELMs prematurely. In perfectly axisymmetric diverted plasmas, the equilibrium separatrix associated with an X-point is composed of a stable and an unstable manifold that perfectly overlay. However, when non-axisymmetric magnetic fields perturb such an axisymmetric configuration, the stable and unstable manifolds do not overlay anymore, and complex topological structures, known as homoclinic tangles or magnetic lobes, arise from the intersection between these two manifolds. This process is usually referred to as separatrix splitting. When magnetic field lines from inside the perturbed plasma volume connect to the divertor plates through intersections of the magnetic lobes with the first wall, structures termed magnetic footprints appear. Most of the exhausted heat and particles from the confined plasma are deposited within the magnetic footprints on the divertor plates and, depending on the plasma conditions, damaging hot spots can appear, thus reducing their lifetime. This proposal aims to use the state-of-the-art plasma transport code EMC3-EIRENE to simulate transport in the edge and SOL of ASDEX Upgrade plasmas subject to RMP fields composed mainly of higher toroidal harmonics. These simulations allow us to predict the particle and heat flux patterns within the magnetic footprints on the divertor plates, which will then be compared with experimental measurements. To accomplish that, the student will spend 12 months at the Max-Planck-Institut für Plasmaphysik (IPP), in Garching - Germany, under the supervision of Dr. Dominik Brida, to learn how to run EMC3-EIRENE. During his stay at IPP Garching, the student will be trained using MHD equilibria reconstructed from experiments carried out on ASDEX Upgrade. This approach will allow the student to get involved in modern fusion research in the tokamak with the highest relevance for fusion research in Europe after the end of JET, especially for power exhaust (due to its high heating power and full tungsten wall), and also to acquire the necessary knowledge for simulating plasma transport in the edge and SOL of TCABR plasmas.