The role of electron-scale turbulence in the JET tokamak: experiments and modelling
The role of electron-scale turbulence in the JET tokamak: experiments and modelling
复制标题
电子级湍流在 JET 托卡马克中的作用：实验和建模
DOI：
10.1088/1741-4326/ac146e
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发表时间：
2021
期刊：
影响因子：
3.3
通讯作者：
Jet Contributors
中科院分区：
文献类型：
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作者：
P. Mantica;N. Bonanomi;A. Mariani;P. Carvalho;E. Delabie;J. Garcia;N. Hawkes;T. Johnson;D. Keeling;M. Sertoli;G. Staebler;G. Szepesi;D. Taylor;A. Thorman;Jet Contributors
在JET-ILW托卡马克的L模和h模氘等离子体中进行了专门的电子热输运实验，以确定电子尺度电子温度梯度（ETG）模式携带的电子热量。不同位置的离子回旋共振加热可以探测电子温度逆梯度长度R/L Te对电子热流通量q e变化的响应，而不同量的中性束加热可以扫描离子与电子温度的比值Te /T i，这是ETGs发生的关键参数。结果表明，标准化q e/ R/L曲线在R/L Te ~ 8以上，Te /T i≥1，表明ETG开始。离子尺度的陀螺动力学（GK）模拟与离子热流和低R/L - Te部分的q - e曲线相匹配，但在高R/L - Te时没有重现这种陡变。覆盖离子和电子尺度的多尺度GK模拟表明，仅当R/L Te值大于实验值时，ETG的贡献才会增加。由于数值资源的限制，很难对这一结果进行敏感性研究。准线性TGLF模型已用于敏感性研究。在与GK多尺度相同的杂束情况下，TGLF在更大的R/L - Te值下显示出比实验更大的q - e陡化，但在忽略重杂质的情况下，TGLF更接近实验结果。包括轻杂质和重杂质在内的TGLF的剖面模拟显示了对T e剖面的过度预测，在某些情况下也对密度的预测，但对T i的预测很好，证实了这些等离子体模型电子刚度的问题。
Dedicated electron heat transport experiments have been carried out in L- and H-mode Deuterium plasmas of the JET-ILW tokamak to identify the amount of electron heat carried by electron-scale electron temperature gradient (ETG) modes. Ion cyclotron resonance heating at different positions has been used to probe the response of the electron temperature inverse gradient length R/L Te to changes in electron heat flux q e, while different amounts of neutral beam heating allowed to scan the ratio of ion to electron temperature T e/T i, which is a key parameter for the onset of ETGs. Results indicate a steepening of the normalized q e vs R/L Te curve above R/L Te ∼ 8 for T e/T i ⩽ 1, suggestive of the ETG onset. Ion-scale gyro-kinetic (GK) simulations match the ion heat flux and the low-R/L Te part of the q e curve, but do not reproduce such steepening at high R/L Te. Multi-scale GK simulations covering both ion and electron scales and including one impurity bundling light and heavy species indicate an ETG contribution only for R/L Te values larger than the experimental ones. Sensitivity studies of such result are difficult to achieve due to limitation in numerical resources. The quasi-linear TGLF model has been used for sensitivity studies. With the same bundled impurity as the GK multi-scale, TGLF shows the q e steepening at much larger R/L Te values than in experiment, but when using the real mix of light impurities neglecting the heavy impurities, TGLF gets closer to the experimental results. Profile simulations with TGLF including both light and heavy impurities show over-prediction of T e profiles and in some cases also of density, but good T i predictions, confirming issues with the model electron stiffness for these plasmas.