Speaker
Description
Core contamination is a key issue for full Tungsten devices and will be a major concern for the operation of ITER. Today’s experiments on medium size tokamaks such as WEST or AUG are vital to further characterize the mechanisms at play that regulate Tungsten concentration. WEST for instance, is characterized by a near-constant radiated fraction, regardless of input power. To better understand experimental observations and predict core contamination, the computational domain of the edge plasma code SOLEDGE-3X is now extended to describe the plasma from the first wall to the core including Tungsten. It self-consistently models the main ion species (usually a Hydrogen isotope), as well as light and heavy impurities in the core and in the edge, performing integrated simulations of plasma scenarios. On the wall, the gross erosion is estimated using the Eckstein formula, supplemented by prompt redeposition from both an analytical formula [1] and a neural network [2]. In the core, a new 1D model is used that solves particle and energy balance for all species, and is time-evolved along with the 2D edge-SOL. Core turbulence is taken into account using QLKNN-10D [3], a neural network trained on a database of QuaLiKiz simulations [4]. In addition, Neoclassical transport of heavy impurities is accounted for in the core using a reduced model benchmarked against NEO, that takes rotational effects into account [5]. Using this framework, tungsten sources, transport and radiation are investigated. A special focus is put on understanding self-regulation mechanisms, in particular the feedback between Tungsten sources and core radiation, which impacts the power entering the scrape-off layer.
REFERENCES:
D. Tskhakaya and M. Groth, Journal of Nuclear Materials 463 (2015): 624–628
L. Cappelli et al., PPCF 65, no. 9 (2023): 095001
K. L. Van De Plassche et al., PoP 27, no. 2 (2020): 022310
Stephens, C.D., X. Garbet, J. Citrin, C. Bourdelle, K.L. van de Plassche, and F. Jenko., Journal of Plasma Physics 87, no. 4 (2021): 905870409.
P. Maget et al, PPCF 62, 105001 (2020); D. Fajardo et al, PPCF 64, 055017 (2022)
