Kinetic modeling of ELM-induced tungsten transport in a tokamak plasma
Kinetic modeling of ELM-induced tungsten transport in a tokamak plasma
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DOI：
10.1063/1.5092319
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发表时间：
2019-04
影响因子：
2.2
通讯作者：
D. V. van Vugt;G. Huijsmans;M. Hoelzl;A. Loarte
中科院分区：
文献类型：
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作者：
D. V. van Vugt;G. Huijsmans;M. Hoelzl;A. Loarte
堆芯等离子体中的杂质积累导致燃料稀释和更高的辐射损失，这可能导致H模式的损失、等离子体的热塌缩，并且最终甚至导致托卡马克中的中断。在目前的实验中，它已被证明，在足够高的频率的边缘局部模式（ELMs），以防止W积累在核心，从边缘等离子体区域驱逐杂质，从而防止它们渗透到等离子体核心。我们提出了一个全轨道粒子扩展的MHD代码JOREK适合于模拟杂质输运过程中ELMs。该模型已被应用到模拟的ELM崩溃ASDEX升级，在那里我们已经量化的W粒子穿过通量表面的位移。输运机制是由于ELM下的MHD不稳定性产生的电场引起的粒子E × B漂移。向内和向外的传输被观察到为一系列交换运动，导致超扩散行为。这不仅使等离子体基座附近的粒子向外移动，而且使基座外部的粒子向内移动。这对ITER中的W操作具有重要影响，在那里它预计将在基座中被屏蔽，并且这里显示的ELM可以增加核心W密度。与现有的扩散建模的比较，示出了定性的协议和这种简化的建模方法的局限性。在核心等离子体中的杂质积累导致燃料稀释和更高的辐射损失，可以导致H-模式的损失，等离子体的热崩溃，最终甚至在托卡马克中断。在目前的实验中，它已被证明，在足够高的频率的边缘局部模式（ELMs），以防止W积累在核心，从边缘等离子体区域驱逐杂质，从而防止它们渗透到等离子体核心。我们提出了一个全轨道粒子扩展的MHD代码JOREK适合于模拟杂质输运过程中ELMs。该模型已被应用到模拟的ELM崩溃ASDEX升级，在那里我们已经量化的W粒子穿过通量表面的位移。输运机制是由于ELM下的MHD不稳定性产生的电场引起的粒子E × B漂移。向内和向外的传输被观察到为一系列交换运动，导致超扩散行为。这个C…
Impurity accumulation in the core plasma leads to fuel dilution and higher radiative losses that can lead to loss of the H-mode, to thermal collapse of the plasma, and eventually even to a disruption in tokamaks. In present experiments, it has been shown that Edge Localized Modes (ELMs) at sufficiently high frequency are required to prevent W accumulation in the core, by expelling impurities from the edge plasma region, thus preventing their penetration into the plasma core. We present a full-orbit particle extension of the MHD code JOREK suitable for simulating impurity transport during ELMs. This model has been applied to the simulation of an ELM crash in ASDEX Upgrade, where we have quantified the displacement of W particles across flux surfaces. The transport mechanism is shown to be the particle E × B-drifts due to the electric field created by the MHD instability underlying the ELM. In- and outward transport is observed as a series of interchange motions, leading to a superdiffusive behavior. This causes not only the particles near the plasma pedestal to move outwards but also the particles outside of the pedestal to move inwards. This has important consequences for operation with W in ITER, where it is expected to be screened in the pedestal, and ELMs are shown here to increase the core W density. A comparison with existing diffusive modeling is made, showing a qualitative agreement and the limitations of this simplified modeling approach.Impurity accumulation in the core plasma leads to fuel dilution and higher radiative losses that can lead to loss of the H-mode, to thermal collapse of the plasma, and eventually even to a disruption in tokamaks. In present experiments, it has been shown that Edge Localized Modes (ELMs) at sufficiently high frequency are required to prevent W accumulation in the core, by expelling impurities from the edge plasma region, thus preventing their penetration into the plasma core. We present a full-orbit particle extension of the MHD code JOREK suitable for simulating impurity transport during ELMs. This model has been applied to the simulation of an ELM crash in ASDEX Upgrade, where we have quantified the displacement of W particles across flux surfaces. The transport mechanism is shown to be the particle E × B-drifts due to the electric field created by the MHD instability underlying the ELM. In- and outward transport is observed as a series of interchange motions, leading to a superdiffusive behavior. This c...