论文标题
数据驱动的转移等离子分离预测模型
Data-driven model for divertor plasma detachment prediction
论文作者
论文摘要
我们提出了一个快速准确的数据驱动的替代模型,用于分离等离子分离预测,利用机器学习研究中的潜在特征空间概念。我们的方法涉及构建和培训两个神经网络。通过压缩多模式诊断测量值,使用多模式诊断测量值和使用多层感知(MLP)的正向模型来找到等离子状态的适当潜在空间表示(LSR)的自动编码器,该模型将一组等离子控制参数投影到其相应的LSR上。通过结合自动编码器的前向模型和解码器网络,这种新的数据驱动的替代模型能够根据一些基于一些血浆控制参数来预测一组一致的诊断测量值。为了确保正确捕获至关重要的分离物理学,在本研究中使用高效的1D UEDGE模型来生成训练和验证数据。数据驱动的替代模型和UEDGE模拟之间的基准表明,我们的替代模型能够提供准确的分离预测(通常在几个百分之几的相对误差边距)中,但至少有四个数量级的速度速度,这表明性能方面有可能促进集成的Tokamak设计和血浆控制。与广泛使用的两点模型和/或两点模型格式相比,新的数据驱动模型具有额外的分离前预测,并且可以轻松扩展以融合更丰富的物理。这项研究表明,复杂的分流和刮擦层等离子体状态在潜在空间中具有低维度。了解潜在空间中的血浆动态并利用这些知识可以为磁融合能量研究中的血浆控制打开新的途径。
We present a fast and accurate data-driven surrogate model for divertor plasma detachment prediction leveraging the latent feature space concept in machine learning research. Our approach involves constructing and training two neural networks. An autoencoder that finds a proper latent space representation (LSR) of plasma state by compressing the multi-modal diagnostic measurements, and a forward model using multi-layer perception (MLP) that projects a set of plasma control parameters to its corresponding LSR. By combining the forward model and the decoder network from autoencoder, this new data-driven surrogate model is able to predict a consistent set of diagnostic measurements based on a few plasma control parameters. In order to ensure that the crucial detachment physics is correctly captured, highly efficient 1D UEDGE model is used to generate training and validation data in this study. Benchmark between the data-driven surrogate model and UEDGE simulations shows that our surrogate model is capable to provide accurate detachment prediction (usually within a few percent relative error margin) but with at least four orders of magnitude speed-up, indicating that performance-wise, it has the potential to facilitate integrated tokamak design and plasma control. Comparing to the widely used two-point model and/or two-point model formatting, the new data-driven model features additional detachment front prediction and can be easily extended to incorporate richer physics. This study demonstrates that the complicated divertor and scrape-off-layer plasma state has a low-dimensional representation in latent space. Understanding plasma dynamics in latent space and utilizing this knowledge could open a new path for plasma control in magnetic fusion energy research.