Speaker
Description
Mitigating the heat load to the divertor is a key challenge for future fusion reactors. Current material limits constrain the allowable heat flux to below 10 MW/m², requiring a significant fraction of the power exhausted from the core plasma to be radiated to maintain acceptable conditions at the divertor. In next-step devices, such as ITER and DEMO, sustained operation without damage demands that 60–75% of the total loss power in ITER (approximately 150 MW) and up to 95% in DEMO be radiated away. This can be achieved through impurity seeding, which promotes divertor detachment by forming a radiating region near the X-point that dissipates most of the exhaust energy. However, excessive impurity injection can cause core contamination and trigger disruptions. Understanding the stability and intensity of the radiation front is therefore essential for protecting the plasma and the machine. In this work, we propose a method to estimate both the position and intensity of the radiator, along with their uncertainties, using a maximum likelihood tomographic reconstruction technique. This approach enables the determination of the local radiated power and energy distribution around the X-point, supporting the analysis of radiator motion and MARFE formation. Furthermore, a first statistical study of impurity-seeded JET discharges is presented, identifying preliminary stability regions and potential local power-balance indicators for real-time control of the radiative regimes.
