Speaker
Description
Efficient power exhaust is a critical challenge for fusion power plants. The so‑called X‑point radiator (XPR) has been proposed as a promising concept to redistribute and dissipate heat loads via impurity radiation.
While detailed edge‑plasma simulations provide valuable insights, they are computationally intensive and therefore not ideally suited for rapid design iteration or extensive parameter scans. A promising alternative is offered by a flight-simulator-type framework such as Fenix [1], which incorporates the equilibrium solver FEQIS [2] and the plasma transport solver ASTRA [3] to simulate plasma behaviour and equilibrium, as well as a simulated control system based on the Plasma Control System Simulation Platform [4]. This combination enables simultaneous modelling of the interaction between the reactor’s control system and the plasma dynamics.
ASTRA is equipped with physics modules that allow it to capture more complex plasma phenomena. In this work, we extend the reduced modelling approach for the X‑point radiator developed in [5]. By imposing a pressure balance between upstream and X‑point parameters, main‑ion and impurity densities at the X-point are obtained. A simple model based on a detachment qualifier [6] is used to estimate the amount of neutral particles at the X-point. Moreover, an approach to predict ELM suppression phases is implemented.
The model is validated in Fenix against ASDEX Upgrade discharges with nitrogen seeding. The reduced XPR model successfully predicts the formation of the XPR and the evolution of its position. Furthermore, experimental radiation measurements are reproduced, and the temporal evolution of the simulated density and temperature profiles shows good agreement with experimental data.
[1] P. David et al 2025 Open Plasma Sci. 1 3
[2] E. Fable et al 2025 Open Plasma Sci. 1 2
[3] G. V. Pereverzev and P. N.Yushmanov 2002 ASTRA. Automated System for Transport Analysis in a Tokamak. IPP Report Nr. 5-98
[4] M. L. Walker et al 2014 Fusion Engineering and Design 89 518-522
[5] U. Stroth et al 2022 Nucl. Fusion 62 076008
[6] A. Kallenbach et al 2015 Nucl. Fusion 55 053026