用于ASDEX Upgrade的AXUV合成诊断及其在SPI模拟中的应用
AXUV synthetic diagnostic for ASDEX Upgrade and its application for SPI simulations
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中文总结 AI 辅助
本研究开发了基于Cherab-Raysect框架的AXUV合成诊断工具，用于AUG托卡马克SPI模拟与实验测量的关联，高Ne含量弹丸的模拟与实验吻合度良好。
中文摘要 AI 辅助
我们推出了一种基于绝对扩展极紫外（Absolute eXtended UltraViolet，AXUV）二极管的相机正向建模工具，以支持缓解等离子体破裂模拟的验证及实验现象的解释，该工具应用于ASDEX Upgrade（AUG）托卡马克。AXUV二极管可测量宽光谱范围内的电磁辐射，其时间分辨率（约微秒级）远高于箔片 bolometer（约毫秒级），但存在光谱响应度不均匀的问题。AXUV适用于研究快速现象，如破碎弹丸注入（Shattered Pellet Injection，SPI），其辐射定位和辐射功率可提供弹丸材料沉积的相关信息。由于AXUV二极管的特性及退化问题，绝对功率测量存在较大的系统不确定性，尤其在光谱随时间变化的场景中，如混合Ne/D₂ SPI实验。这些挑战促使我们在Cherab-Raysect光学建模框架内开发了一种合成诊断工具，该工具应用于AUG两个极向截面的四台AXUV相机。该合成诊断工具可帮助理解SPI条件下二极管对辐射的测量方式，并将第一性原理等离子体模拟与实验测量关联起来。本文介绍了该合成诊断的细节，并通过应用于JOREK中开展的AUG SPI模拟展示其能力。将这些模拟生成的合成信号与2022年SPI实验的实验测量结果进行比较，发现二者在诸多方面具有定性相似的特征。其中，研究的高Ne含量（10%）弹丸的时间演化吻合度特别好，而另一种低Ne含量（0.17%）的情况则表现出更明显的差异，这可能是由于基础SPI模拟中未包含背景杂质所致。
英文摘要
We introduce an Absolute eXtended UltraViolet (AXUV) diode-based camera forward-modelling tool to support the validation of mitigated disruption simulations and the interpretation of experimental phenomena, with applications to the ASDEX Upgrade (AUG) tokamak. AXUV diodes measure electromagnetic radiation across a wide spectral range with a significantly higher time resolution (~microseconds) than foil bolometers (~milliseconds), albeit with a non-uniform spectral responsivity. AXUV is suitable for examining fast phenomena, such as shattered pellet injection (SPI), where the radiation localisation and radiated power provide information on the deposition of pellet material. Due to the characteristics and degradation of AXUV diodes, absolute power measurements are subject to large systematic uncertainties, especially when the spectra are time-varying, as in e.g. mixed Ne/D2 SPI experiments. These challenges motivated the development of a synthetic diagnostic within the Cherab-Raysect optical modelling framework, which is applied here to four AXUV cameras in two poloidal cross-sections of AUG. The synthetic diagnostic provides a means to understand how the diodes measure radiation under SPI conditions and to connect first-principles plasma simulations with experimental measurements. The details of the synthetic diagnostic are presented, and the capabilities are illustrated with applications to AUG SPI simulations performed in JOREK. The synthetic signals generated from these simulations are compared with experimental measurements from the 2022 SPI campaign and show qualitatively similar features in many respects. Particularly good agreement was found in the time evolution of the studied high Ne-content (10%) pellet, whereas a different, low Ne-content (0.17%) case exhibited more pronounced differences, likely due to the absence of background impurities in the underlying SPI simulations.
