Advanced surrogate model for electron-scale turbulence in tokamak pedestals
We derive an advanced surrogate model for predicting turbulent transport at the edge of tokamaks driven by electron temperature gradient (ETG) modes. Our derivation is based on a recently developed sensitivity-driven sparse grid interpolation approach for uncertainty quantification and sensitivity analysis at scale, which informs the set of parameters that define the surrogate model as a scaling law. Our model reveals that ETG-driven electron heat flux is influenced by the safety factor q, electron beta βe and normalized electron Debye length λD, in addition to well-established parameters such as the electron temperature and density gradients. To assess the trustworthiness of our model's predictions beyond training, we compute prediction intervals using bootstrapping. The surrogate model's predictive power is tested across a wide range of parameter values, including within-distribution testing parameters (to verify our model) as well as out-of-bounds and out-of-distribution testing (to validate the proposed model). Overall, validation efforts show that our model competes well with, or can even outperform, existing scaling laws in predicting ETG-driven transport.
- Research Organization:
- The University of Texas at Austin, TX (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- FG02-04ER54742
- OSTI ID:
- 2475005
- Journal Information:
- Journal of Plasma Physics, Journal Name: Journal of Plasma Physics Journal Issue: 5 Vol. 90; ISSN 0022-3778; ISSN 1469-7807
- Publisher:
- Cambridge University Press (CUP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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