Sawtooth instabilities can modify heating and current-drive profiles and potentially increase fast-ion losses. Understanding how sawteeth redistribute fast ions as a function of sawtooth parameters and of fast-ion energy and pitch is hence a subject of particular interest for future fusion devices. Here we present the first collective Thomson scattering (CTS) measurements of sawtooth-induced redistribution of fast ions at ASDEX Upgrade. These also represent the first localized fast-ion measurements on the high-field side of this device. The results indicate fast-ion losses in the phase-space measurement volume of about 50% across sawtooth crashes, in good agreement with values predicted with the Kadomtsev sawtooth model implemented in TRANSP and with the sawtooth model in the EBdyna_go code. In contrast to the case of sawteeth, we observe no fast-ion redistribution in the presence of fishbone modes. We highlight how CTS measurements can discriminate between different sawtooth models, in particular when aided by multi-diagnostic velocity-space tomography, and briefly discuss our results in light of existing measurements from other fast-ion diagnostics.
锯齿不稳定性可以改变加热和电流驱动分布，并可能增加快离子损失。因此，理解锯齿如何根据锯齿参数以及快离子的能量和投掷角重新分布快离子，对未来聚变装置尤为重要。本文首次展示了在ASDEX Upgrade装置上利用集体汤姆孙散射（CTS）对锯齿引起的快离子再分布进行的测量。这些测量也是在ASDEX Upgrade高场侧进行的首次局域快离子测量。结果表明，在锯齿崩溃过程中，相空间测量体积内的快离子损失约为50%，这与TRANSP中实现的Kadomtsev锯齿模型以及EBdyna_go代码中的锯齿模型所预测的值吻合良好。与锯齿情形相反，在鱼骨模存在时，我们未观察到快离子的再分布。我们强调了CTS测量如何能够区分不同的锯齿模型，尤其是在多诊断相空间层析成像的辅助下，并简要讨论了我们的结果与现有其他快离子诊断测量结果的比较。