SUPR
Integrated modelling of boron powder injection and its effect on plasma turbulence.
Dnr:

NAISS 2025/22-898

Type:

NAISS Small Compute

Principal Investigator:

Svetlana Ratynskaia

Affiliation:

Kungliga Tekniska högskolan

Start Date:

2025-06-16

End Date:

2025-12-01

Primary Classification:

10303: Fusion, Plasma and Space Physics

Webpage:

Allocation

Abstract

The European Union recognizes fusion energy as the most promising long-term solution for clean virtually unlimited energy, with the construction of ITER and engineering design of EU-DEMO being short- and mid-term objectives of the EUROfusion roadmap. Following a recent re-baselining, boronization has become mandatory for the now all-tungsten ITER reactor; the thin boron wall layer operates as an oxygen getter, reducing oxygen concentration inside the vessel. As a side effect, plasma-induced wall erosion will eventually lead to the generation of boron dust, which could potentially remobilize prematurely and inhibit plasma breakdown. Conversely, the injection of boron can have other beneficial effects for future fusion reactors. Latest experimental fusion advances brought forward a novel way to improve plasma performance - by controlled injection of fine boron powders. The observation of improved energy confinement regimes due to turbulence suppression by boron impurities could be a game changer, but the underlying physical mechanism is not ascertained yet. The understanding of turbulence suppression by boron powder injection is a multi-physics problem that requires integrated modelling. The merging of numerical tools that simulate dust dynamics and ablation, impurity production and transport as well as plasma turbulence lies at the frontiers of computational efforts. A research project has been jointly initiated by KTH and DTU, aiming at accurately modelling boron dust transport and survivability in fusion plasmas as well as at self-consistently modelling the effect of injected boron powder on plasma edge profiles and turbulence. Such goals shall be achieved by the coupling of two state-of-the-art numerical tools: MIGRAINe and HESEL. MIGRAINe, developed and maintained by the Complex Plasmas Group of the SPP Division of KTH, is the only dust transport code currently employed for ITER and for DEMO predictions, since its physics model realistically describes microphysical processes and plasma collection by dust in reactor relevant conditions. HESEL, developed and maintained by the Plasma Physics and Fusion Energy Division of DTU, implements a self-consistent fluid-based model derived from first principles that describes the full dynamics of the edge and scrape-off layer plasmas, including the full temperature dynamics of ions and electrons. It has recently been coupled to the PISAM model, a full 3D discrete particle model tailored for modeling the transport of neutral atoms and molecules in fusion plasmas. The MIGRAINe code will be used to generate dynamic sources of impurity neutrals, which will then be processed and sent as input to HESEL-PISAM in order to evaluate the physics behind turbulence suppression. We here request computational resources necessary to carry out the preliminary phase of the investigation, consisting in the identification of an efficient and physics-informed workflow for coupling the two codes. For the MIGRAINe and HESEL-PISAM models address processes that unfold on distinct time scales - dust transport over milliseconds and turbulence on sub-millisecond scales – explorative runs are required to identify the most physically sound and computationally cost-effective strategy for dynamically interchanging data on separate time-step scales.