arXiv:2607.21407physics.comp-phcs.AI2026-07

用神经网络快速预测托卡马克等离子体边界状态,还能反推控制参数并评估不确定性。

Cycle-Consistent and Uncertainty-Aware Neural Surrogates for Tokamak Edge Plasmas

论文配图:Cycle-Consistent and Uncertainty-Aware Neural Surrogates for Tokamak Edge Plasmas
图 1 · 摘自论文原文
  • 构建前后向一致的神经模型,无需真实标签即可自监督验证预测可靠性。
  • 前向预测误差低于2.6%,所有控制参数反推相关系数超0.97,精度高。
  • 支持实时控制与数字孪生,适合等离子体优化与未来装置研发人员使用。

等离子体边界和偏滤器区域决定托卡马克的功率与粒子排出方式,影响热流、靶材条件及脱附触发。精确预测这些量对当前及未来装置运行至关重要,但解析这些过程的仿真速度过慢,难以用于参数扫描、优化或实时控制。机器学习代理模型可提供快速替代方案,但多数为单向模型,无法从观测数据反推输入参数,也难评估预测可靠性。本文提出一种循环一致性神经代理模型,结合条件U-Net前向模型与基于冻结前向网络的优化反演方法。前向模型将五个控制参数映射到SOLPS-ITER网格上的二维等离子体态场;反演方法通过强制前向与反向预测一致实现自监督质量检验,无需真实标签。同时,一个包含多层感知机的集合模型预测外板中平面及偏滤器靶区的电子温度与密度剖面,并给出不确定性估计,提示需补充模拟的位置。前向模型在所有场上的归一化均方根误差低于2.6%,皮尔逊相关系数高于0.95。循环一致性正则化使平均循环$R^2$从0.59提升至0.99,未降低前向精度,并实现核心燃料注入率恢复;全部五个控制参数反推相关系数均≥0.97。$k$-d树热启动使数据库完成率超过95%,冷启动仅约30%成功。模型参数量约$4\times10^6$,毫秒级生成完整二维预测,比SOLPS-ITER快五至六数量级,支持实时控制、参数扫描、不确定性分析与数字孪生。

原文摘要 · Abstract (English)

The boundary and divertor plasma govern how a tokamak exhausts power and particles, setting heat fluxes, target conditions, and the onset of detachment. Predicting these quantities is essential for operating current and future devices, but edge simulations that resolve them are too slow for parameter scans, optimization, or real-time control. Machine-learning surrogates offer a fast alternative, yet most are forward-only: they cannot recover input parameters from observations or assess the reliability of their predictions. We introduce a cycle-consistent neural surrogate for edge plasmas, combining a conditional U-Net forward model with an optimization-based inverse method built on the frozen forward network. The forward model maps five control parameters to two-dimensional plasma-state fields on the SOLPS-ITER mesh; the inverse method enforces consistency between forward and inverse predictions, a self-supervised quality check needing no ground-truth labels at inference. An ensemble of multilayer perceptrons also predicts electron temperature and density profiles at the outboard midplane and divertor targets, with uncertainty estimates that flag where more simulations are needed. The forward model achieves normalized root-mean-square errors below 2.6% and Pearson correlations above 0.95 for all fields. Cycle-consistency regularization raises the average cyclical $R^2$ from 0.59 to 0.99 without degrading forward accuracy and enables recovery of the core fueling rate; all five control parameters are recovered with Pearson $r\ge0.97$. A $k$-d tree warm start yields a database completion rate above 95%, versus roughly 30% outright failures when cold-started. With about $4\times10^6$ parameters, the model produces full 2D predictions in milliseconds, five to six orders of magnitude faster than SOLPS-ITER, enabling real-time control, parameter scans, uncertainty analysis, and digital twins.

等离子体神经网络实时控制不确定性

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