Towards fast surrogate models for interpolation of tokamak edge plasmas

One of the major design limitations for tokamak fusion reactors is the heat load that can be sustained by the materials at the divertor target. Developing a full understanding of how machine or operation parameters affect the conditions at the divertor requires an enormous number of simulations. A p...

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Main Authors: Stefan Dasbach, Sven Wiesen
Format: Article
Language:English
Published: Elsevier 2023-03-01
Series:Nuclear Materials and Energy
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S2352179123000352
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author Stefan Dasbach
Sven Wiesen
author_facet Stefan Dasbach
Sven Wiesen
author_sort Stefan Dasbach
collection DOAJ
description One of the major design limitations for tokamak fusion reactors is the heat load that can be sustained by the materials at the divertor target. Developing a full understanding of how machine or operation parameters affect the conditions at the divertor requires an enormous number of simulations. A promising approach to circumvent this is to use machine learning models trained on simulation data as surrogate models. Once trained such surrogate models can make fast predictions for any scenario in the design parameter space. In future such simulation based surrogate models could be used in system codes for rapid design studies of future fusion power plants. This work presents the first steps towards the development of such surrogate models for plasma exhaust and the datasets required for their training. Machine learning models like neural networks usually require several thousand data points for training, but the exact amount of data required varies from case to case. Due to the long runtimes of simulations we aim at finding the minimal amount of training data required. A preliminary dataset based on SOLPS-ITER simulations with varying tokamak design parameters, including the major radius, magnetic field strength and neutral density is constructed. To be able to generate more training data within reasonable computation time the simulations in the dataset use fluid neutral simulations and no fluid drift effects. The dataset is used to train a simple neural network and Gradient Boosted Regression Trees and test how the performance depends on the number of training simulations.
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spelling doaj.art-d5a5c272a0eb42e7bb8a0d767ac4e55a2023-03-12T04:21:36ZengElsevierNuclear Materials and Energy2352-17912023-03-0134101396Towards fast surrogate models for interpolation of tokamak edge plasmasStefan Dasbach0Sven Wiesen1Corresponding author.; Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung - Plasmaphysik, Jülich, 52425, GermanyForschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung - Plasmaphysik, Jülich, 52425, GermanyOne of the major design limitations for tokamak fusion reactors is the heat load that can be sustained by the materials at the divertor target. Developing a full understanding of how machine or operation parameters affect the conditions at the divertor requires an enormous number of simulations. A promising approach to circumvent this is to use machine learning models trained on simulation data as surrogate models. Once trained such surrogate models can make fast predictions for any scenario in the design parameter space. In future such simulation based surrogate models could be used in system codes for rapid design studies of future fusion power plants. This work presents the first steps towards the development of such surrogate models for plasma exhaust and the datasets required for their training. Machine learning models like neural networks usually require several thousand data points for training, but the exact amount of data required varies from case to case. Due to the long runtimes of simulations we aim at finding the minimal amount of training data required. A preliminary dataset based on SOLPS-ITER simulations with varying tokamak design parameters, including the major radius, magnetic field strength and neutral density is constructed. To be able to generate more training data within reasonable computation time the simulations in the dataset use fluid neutral simulations and no fluid drift effects. The dataset is used to train a simple neural network and Gradient Boosted Regression Trees and test how the performance depends on the number of training simulations.http://www.sciencedirect.com/science/article/pii/S2352179123000352SolpsPlasma exhaustDivertorSurrogateMachine learningNeural network
spellingShingle Stefan Dasbach
Sven Wiesen
Towards fast surrogate models for interpolation of tokamak edge plasmas
Nuclear Materials and Energy
Solps
Plasma exhaust
Divertor
Surrogate
Machine learning
Neural network
title Towards fast surrogate models for interpolation of tokamak edge plasmas
title_full Towards fast surrogate models for interpolation of tokamak edge plasmas
title_fullStr Towards fast surrogate models for interpolation of tokamak edge plasmas
title_full_unstemmed Towards fast surrogate models for interpolation of tokamak edge plasmas
title_short Towards fast surrogate models for interpolation of tokamak edge plasmas
title_sort towards fast surrogate models for interpolation of tokamak edge plasmas
topic Solps
Plasma exhaust
Divertor
Surrogate
Machine learning
Neural network
url http://www.sciencedirect.com/science/article/pii/S2352179123000352
work_keys_str_mv AT stefandasbach towardsfastsurrogatemodelsforinterpolationoftokamakedgeplasmas
AT svenwiesen towardsfastsurrogatemodelsforinterpolationoftokamakedgeplasmas