用物理约束神经网络,让少数据也能高精度模拟核聚变湍流输运。
TGLF-WINN: Data-Efficient Deep Learning Surrogate for Turbulent Transport Modeling in Fusion
- 设计波数感知特征和正则化,让模型学习更简单、泛化更强。
- 在仅1/9训练数据下,误差比传统方法低一个数量级。
- 结合主动学习,25%数据就能达到全量数据的准确率,适合真实场景。
托卡马克中湍流输运的快速精确预测对核聚变研究至关重要,但全装置模拟需数千次评估,计算成本高。基于神经网络的代理模型虽可加速推理并支持梯度耦合,但通常需要大量训练数据以覆盖不同等离子体条件下的通量变化,导致训练负担重且难以应用于昂贵的漂移动力学仿真。本文提出TGLF-WINN(波数感知神经网络),包含三项创新:(1) 有原则的特征工程降低目标预测范围,简化学习任务;(2) 物理引导的波数解析正则化,提升稀疏数据下的泛化能力;(3) 贝叶斯主动学习(BAL),根据模型不确定性策略选取训练样本,显著降低数据需求。特征调优与波数正则化联合使相对均方对数误差(RMSLE)较TGLF-NN降低12.5%;在稀疏、未过滤训练数据(约全量1/9)下,其误差增长仅为TGLF-NN的十分之一。引入贝叶斯主动学习后,仅用25%训练数据即可达到与全量数据训练的TGLF-NN相当的精度,误差距离全量基准仅2.8%,相比自身全量结果仅差4.3%。下游通量匹配工作流验证其实用性:该神经网络代理相较原TGLF模型提速45倍,重建精度相当。
原文摘要 · Abstract (English)
The Trapped Gyro-Landau Fluid (TGLF) model provides fast, accurate predictions of turbulent transport in tokamaks, but whole device simulations requiring thousands of evaluations remain computationally expensive. Neural network (NN) surrogates offer accelerated inference with fully differentiable approximations that enable gradient-based coupling but typically require large training datasets to capture transport flux variations across plasma conditions, creating significant training burden and limiting applicability to expensive gyrokinetic simulations. We propose TGLF-WINN (Wavenumber-Informed Neural Network) with three key innovations: (1) principled feature engineering that reduces target prediction range, simplifying the learning task; (2) physics-guided wavenumber-resolved regularization to improve generalization under sparse data; and (3) Bayesian Active Learning (BAL) to strategically select training samples based on model uncertainty, reducing data requirements while maintaining accuracy. Feature tuning and wavenumber regularization together deliver a 12.5% relative RMSLE reduction over TGLF-NN on the full dataset; under sparse, unfiltered training (approximately 1/9 the full size) they yield an order-of-magnitude smaller RMSLE degradation than TGLF-NN, with the wavenumber-informed regularization imposing a physics-guided constraint on per-mode fluxes. Adding Bayesian Active Learning, TGLF-WINN matches TGLF-NN's full-data offline accuracy using only 25% of the training data, within 2.8% of TGLF-NN's full-data baseline and 4.3% of our own full-data result. A downstream flux-matching workflow further shows practicality: the NN surrogate gives a 45x speedup over TGLF with comparable reconstruction accuracy.
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