A library of surrogate models for tokamak fusion.
This library provides both inference code and model weights and metadata. It is designed to provide surrogate models for TORAX, but the models should be usable by other fusion simulators.
Currently, this library only holds the QLKNN_7_11 model. This model is a surrogate of Qualikiz, a quasilinear gyrokinetic code for turbulent transport in tokamaks.
It is based on the original QLKNN10D model by Van de Plassche et al. PoP 2020 (also available on arxiv). It was trained by combining data for the QLKNN11D dataset and QLKNN7D-edge dataset. A paper describing the details of the model is in the works and should be published soon.
The model takes as input:
- Normalized logarithmic heat and density gradients for electrons and main
ions (
$$R/L_{Te}$$ ,$$R/L_{Ti}$$ ,$$R/L_{ne}$$ ,$$R/L_{ni}$$ ) - Safety factor (
$$q$$ ) - Magnetic shear (
$$\hat{s}$$ ) - Local inverse aspect ratio (
$$r/R_{maj}$$ ) - ion-electron temperature ratio (
$$T_i/T_e$$ ) - Logarithmic ion-electron normalized collisionality (
$$\mathrm{log}(\nu^*)$$ ) - Normalized density (
$$n_i/n_e$$ )
It outputs ion and electron heat and particle fluxes for each transport mode (Ion Temperature Gradient [ITG], Electron Temperature Gradient [ETG], Trapped Electron Modes [TEM]), as well as the the maximum growth rate on ion gyroradius scales. Specifically, we output the leading flux for that mode (ion heat flux for ITG, electron heat flux for TEM and ETG), and ratios of the relevant secondary fluxes to the leading flux of that mode.
More details on the inputs and outputs mentioned above can be found in the Qualikiz documentation.
It is recommended to use a virtual environment to install fusion_surrogates.
To install venv:
pip install --upgrade pip
pip install virtualenvTo create and activate a venv:
python3 -m venv .venv
source .venv/bin/activateOnce you are done with your session, you can exit the venv:
deactivateTo install the library:
pip install fusion_surrogatesIf you want to run unit tests, install with the testing option:
pip install -e .[testing]
pytest .venv/lib/python*/site-packages/fusion_surrogatesCopyright 2025 Google LLC
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