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  • Neural network surrogate of QuaLiKiz using JET experimental data to populate training space
    Ho, A. ...
    Within integrated tokamak plasma modeling, turbulent transport codes are typically the computational bottleneck limiting their routine use outside of post-discharge analysis. Neural network (NN) ... surrogates have been used to accelerate these calculations while retaining the desired accuracy of the physics-based models. This paper extends a previous NN model, known as QLKNN-hyper-10D, by incorporating the impact of impurities, plasma rotation, and magnetic equilibrium effects. This is achieved by adding a light impurity fractional density (nimp,light/ne) and its normalized gradient, the normalized pressure gradient (%), the toroidal Mach number (Mtor), and the normalized toroidal flow velocity gradient. The input space was sampled based on experimental data from the JET tokamak to avoid the curse of dimensionality. The resulting networks, named QLKNN-jetexp-15D, show good agreement with the original QuaLiKiz model, both by comparing individual transport quantity predictions and by comparing its impact within the integrated model, JINTRAC. The profile-averaged RMS of the integrated modeling simulations is <10% for each of the five scenarios tested. This is non-trivial given the potential numerical instabilities present within the highly nonlinear system of equations governing plasma transport, especially considering the novel addition of momentum flux predictions to the model proposed here
    Source: Physics of plasmas. - ISSN 1070-664X (Vol. 28, Iss. 3, 2021, 23 str.)
    Type of material - article, component part
    Publish date - 2021
    Language - english
    COBISS.SI-ID - 65865475
    DOI

source: Physics of plasmas. - ISSN 1070-664X (Vol. 28, Iss. 3, 2021, 23 str.)
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