A new modeling study has quantified the expected heat loads on the Ion Cyclotron Resonance Heating (ICRH) antenna planned for the Divertor Tokamak Test (DTT) facility. Researchers implemented the three-dimensional edge plasma transport code EMC3-EIRENE for the DTT geometry, first benchmarking it against the established SOLPS-ITER code in an axisymmetric configuration to validate the setup. The primary goal was to assess plasma-surface interactions in a full 3D environment, which is crucial for components like ICRH antennas that break the toroidal symmetry of the tokamak vessel. The simulations provide a detailed map of the heat flux distribution, informing the final engineering design and material choices for plasma-facing components to ensure their survival during high-power operations. Source: arXiv

The EMC3-EIRENE code is a specialized tool for modeling plasma transport in the complex magnetic topology of the scrape-off layer and divertor regions, particularly in non-axisymmetric systems like stellarators or tokamaks with inserted components. For this work, the DTT's ICRH antenna structure was incorporated into the simulation grid. The study explored different assumptions for the antenna's toroidal symmetry to evaluate computational trade-offs and determine the deviation between a full 3D assessment and simpler 2D approximations. This analysis is vital for the Divertor Tokamak Test facility, a European project designed to test advanced divertor concepts and power exhaust solutions for a future DEMO-class fusion power plant. Understanding and mitigating heat loads on auxiliary heating systems is a key part of its research mission.

For this work, the DTT's ICRH antenna structure was incorporated into the simulation grid.

The 3D simulations predict significant, localized heat loads on the antenna's plasma-facing surfaces. According to the preprint, the peak heat flux reaches 0.9 MW/m² on the antenna's top plate, 2.1 MW/m² on one of its side plates, and a maximum of 3.8 MW/m² on the opposing side plate. These values highlight the necessity of 3D modeling, as 2D approximations would fail to capture the complex plasma flow and magnetic field line intersection with the antenna's geometry, leading to a significant underestimation of thermal stress. Such detailed predictions are essential for preventing component failure, which could halt experiments and introduce impurities into the plasma, degrading overall performance. The results provide a quantitative basis for the DTT engineering team to refine the antenna's design and cooling systems.

The study also investigated the effect of active plasma control techniques on these heat loads. Specifically, the model included 3D gas puffing, a common method for dissipating power and reducing plasma temperature near the wall. The simulations evaluated how introducing a neutral gas puff impacts the edge plasma behavior and, consequently, the heat flux distribution across the ICRH antenna. By modeling these mitigation strategies, the research provides a more complete operational picture, allowing for the development of control schemes to protect the antenna during various plasma scenarios. This work serves as a foundational step for more complex, integrated simulations that will guide the operational phase of the DTT and other future fusion devices that rely on ICRH for plasma heating.