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EuroPED-NN: Uncertainty aware surrogate model

A. P. Alvarez
A. Ho
A. Jarvinen
S. Saarelma
S. Wiesen
JET Contributors
Abstract

This work successfully generates uncertainty aware surrogate models, via the Bayesian neural network with noise contrastive prior (BNN-NCP) technique, of the EuroPED plasma pedestal model using data from the JET-ILW pedestal database and subsequent model evaluations. All this conform EuroPED-NN. The BNN-NCP technique is proven to be a good fit for uncertainty aware surrogate models, matching the output results as a regular neural network, providing prediction's confidence as uncertainties, and highlighting the out of distribution (OOD) regions using surrogate model uncertainties. This provides critical insights into model robustness and reliability. EuroPED-NN has been physically validated, first, analyzing electron density ne ⁣(ψpol=0.94)n_e\!\left(\psi_{\text{pol}}=0.94\right) with respect to increasing plasma current, IpI_p, and second, validating the Δβp,ped\Delta-\beta_{p,ped} relation associated with the EuroPED model. Affirming the robustness of the underlying physics learned by the surrogate model.

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