Validating and speeding up x-ray tomographic inversions in tokamak plasmas

IF 2.1 2区物理与天体物理 Q2 PHYSICS, FLUIDS & PLASMAS

Plasma Physics and Controlled Fusion Pub Date : 2024-07-02 DOI:10.1088/1361-6587/ad5b85

A Jardin, D Mazon, J Bielecki, D Dworak, D Guibert, K Król, Y Savoye-Peysson, M Scholz, J Walkowiak and the WEST Team

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引用次数: 0

Abstract

X-ray tomography is a precious tool in tokamaks that provides rich information about the core plasma, such as local impurity concentration, electron temperature and density as well as magnetic equilibrium (ME) and magnetohydrodynamic activity. Nevertheless, inferring the local plasma emissivity from a sparse set of line-integrated measurements is an ill-posed problem that requires dedicated regularization and validation methods. Besides, speeding up the inversion algorithm in order to be compatible with real-time control systems is a challenging task with traditional approaches. In this contribution, in a first part we introduce tools aiming at validating and speeding up the x-ray tomographic inversions based on Tikhonov regularization, including ME constraint and parameter optimization, taking the WEST geometry as an example. In a second part, an alternative approach compatible with real-time, based on a set of neural networks is proposed and compared with the Tikhonov approach for an experimental case.

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验证并加速托卡马克等离子体中的 X 射线断层反演

X 射线层析成像技术是托卡马克中的一项宝贵工具，可提供有关核心等离子体的丰富信息，如局部杂质浓度、电子温度和密度以及磁平衡（ME）和磁流体动力活动。然而，从一组稀疏的线积分测量值推断局部等离子体发射率是一个难以解决的问题，需要专门的正则化和验证方法。此外，加快反演算法的速度以便与实时控制系统兼容，对于传统方法来说也是一项具有挑战性的任务。在本文的第一部分，我们以 WEST 几何为例，介绍了旨在验证和加快基于 Tikhonov 正则化的 X 射线断层反演的工具，包括 ME 约束和参数优化。在第二部分中，我们提出了一种基于神经网络的与实时性兼容的替代方法，并在一个实验案例中与 Tikhonov 方法进行了比较。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Plasma Physics and Controlled Fusion 物理-物理：核物理

CiteScore

4.50

自引率

13.60%

发文量

224

审稿时长

4.5 months

期刊介绍： Plasma Physics and Controlled Fusion covers all aspects of the physics of hot, highly ionised plasmas. This includes results of current experimental and theoretical research on all aspects of the physics of high-temperature plasmas and of controlled nuclear fusion, including the basic phenomena in highly-ionised gases in the laboratory, in the ionosphere and in space, in magnetic-confinement and inertial-confinement fusion as well as related diagnostic methods. Papers with a technological emphasis, for example in such topics as plasma control, fusion technology and diagnostics, are welcomed when the plasma physics is an integral part of the paper or when the technology is unique to plasma applications or new to the field of plasma physics. Papers on dusty plasma physics are welcome when there is a clear relevance to fusion.