arXiv:2502.12182physics.plasm-phcs.AI2025-02被引 2

用可解释的机器学习监控托卡马克等离子体,提升对失稳事件的预警能力。

Towards Transparent and Accurate Plasma State Monitoring at JET

  • 融合有监督与无监督学习,首次在等离子体监测中使用多任务学习。
  • 序列模型预测失稳事件效果优于传统状态模型,交叉验证成功率高。
  • 结果可解释,适合用于控制策略切换与物理机制研究。

托卡马克装置中等离子体的控制与监测极为复杂,异常事件如失稳现象严重阻碍稳态运行,甚至威胁设备安全,是未来聚变电站建设的关键挑战。本文提出一种透明且数据驱动的方法,用于监测杰特(JET)装置中的等离子体状态。基于520次专家标注的放电数据,结合监督与无监督学习技术,首次在等离子体监测中引入多任务学习,构建可解释的状态表征。序列模型在失稳预测上显著优于基于状态的模型。最优网络在结合物理指标并考虑邻近不稳定性时,表现出良好的交叉验证成功率。对学习到的隐空间进行定性分析,揭示了运行区与失稳区的分布模式,以及动态演化特征与全局特征重要性。该方法为控制模式切换、数据分析与潜变量探索提供了新路径,具备满足规避需求的预警时间,其分布与已知物理机制一致,展现出量与质的双重潜力。

原文摘要 · Abstract (English)

Controlling and monitoring plasma within a tokamak device is complex and challenging. Plasma off-normal events, such as disruptions, are hindering steady-state operation. For large devices, they can even endanger the machine's integrity and it represents in general one of the most serious concerns for the exploitation of the tokamak concept for future power plants. Effective plasma state monitoring carries the potential to enable an understanding of such phenomena and their evolution which is crucial for the successful operation of tokamaks. This paper presents the application of a transparent and data-driven methodology to monitor the plasma state in a tokamak. Compared to previous studies in the field, supervised and unsupervised learning techniques are combined. The dataset consisted of 520 expert-validated discharges from JET. The goal was to provide an interpretable plasma state representation for the JET operational space by leveraging multi-task learning for the first time in the context of plasma state monitoring. When evaluated as disruption predictors, a sequence-based approach showed significant improvements compared to the state-based models. The best resulting network achieved a promising cross-validated success rate when combined with a physical indicator and accounting for nearby instabilities. Qualitative evaluations of the learned latent space uncovered operational and disruptive regions as well as patterns related to learned dynamics and global feature importance. The applied methodology provides novel possibilities for the definition of triggers to switch between different control scenarios, data analysis, and learning as well as exploring latent dynamics for plasma state monitoring. It also showed promising quantitative and qualitative results with warning times suitable for avoidance purposes and distributions that are consistent with known physical mechanisms.

等离子体机器学习聚变能源可解释性

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