Speaker
Description
Predicting different key boundary plasma constraints such as peak heat load to divertor targets and first wall, density at the separatrix and impurity influx as a function of the measurable control parameters (i.e. divertor neutral pressure, impurity seeding rate etc.) is crucial to prevent damage to the divertor targets and achieve required core plasma performance in fusion devices. In the case of ITER, experimental scenarios will be designed using a Pulse Design Simulator (PDS) which is currently under development at the ITER Organization. The PDS will operate within the ITER Integrated Modelling Analysis Suite (IMAS) and is being constructed using the third incarnation of the Multiscale Coupling Library and Environment (MUSCLE3) [1]. A key requirement of the PDS is that it be capable of end-to-end scenario design on reasonably rapid timescales and must thus incorporate reduced model actors describing the plasma boundary in connection to a core plasma and relevant measurable control parameters.
Here we examine a variety of candidate boundary models, including Reverse 2-point modelling [2], scaling laws for key divertor and upstream parameters based on the well-established ITER database of high fidelity SOLPS-ITER simulations [3] and neutral networks (SOLPS-NN) [4] trained on the same database . The candidate reduced models are first compared amongst themselves and then tested against new SOLPS-ITER [5] datasets with an improved physics description of the ITER plasma boundary, including simulations for the Start of Research Operations (SRO) phase of the new 2024 ITER re-baseline, under conditions which lie far outside the original training set. These lower power, reduced performance conditions are in fact the most important region to explore from the point of view of PDS development given that they will be the first plasmas which will be encountered in the ITER Research Plan.
MUSCLE3 actors have been generated for each of the reduced models and first steps taken towards their integration into the PDS framework. Early scenario simulation results including these boundary plasma actors for representative SRO cases will be presented.
References:
[1] L.E.Veen et. al.,Computational Science ICSS 2020 425-438 (2020)
[2] P. C. Stangeby, Plasma Physics and Controlled Fusion 60 044022 (2018)
[3] H.D. Pacher et. al., Journal of Nuclear Materials 463 591–595 (2015)
[4] S. Dasbach, Phd Thesis, https://docserv.uni-esseldorf.de/servlets/DocumentServlet?id=69084 (2025)
[5] S. Wiesen et. al., Journal of Nuclear Materials 463 480-484 (2015)