Effect of resonant magnetic perturbations on low collisionality discharges in MAST and a comparison with ASDEX Upgrade
Effect of resonant magnetic perturbations on low collisionality discharges in MAST and a comparison with ASDEX Upgrade
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DOI：
10.1088/0029-5515/55/4/043011
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发表时间：
2014-12
期刊：
影响因子：
3.3
通讯作者：
A. Kirk;W. Suttrop;Yueqiang Liu;I. Chapman;P. Cahyna;T.Eich;C.Fuchs;C.Ham;J. Harrison
中科院分区：
文献类型：
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作者：
A. Kirk;W. Suttrop;Yueqiang Liu;I. Chapman;P. Cahyna;T.Eich;C.Fuchs;C.Ham;J. Harrison
利用具有各种环形模数的共振磁扰动（RMPs），在大范围的低至中等碰撞放电中，在MAST和AUG上实现了持续边缘局域模式（ELM）缓解。在引流器目标处，ELM能量损失和峰值热负荷都降低了。ELM缓解阶段通常与等离子体密度和总存储能量的下降有关。在MAST上的一个特定场景中，通过仔细调整燃料，可以抵消密度的下降，并产生具有减轻elm的等离子体，减少峰值导流器热通量，并将基座高度和受限能量的退化降到最低。虽然所施加的谐振磁扰动场可以很好地指示MAST和AUG上ELM减缓的开始，但在某些情况下并非如此，这显然强调需要考虑等离子体对所施加扰动的响应。等离子体响应计算表明，ELM频率的增加与等离子体边缘剥离-撕裂响应的大小和等离子体边界在x点区域的畸变有关。在许多情况下，RMPs会增加I型elm的频率，然而，也有I型elm被抑制的例子，并且会过渡到较小或IV型elm的形成机制。
Sustained edge localized mode (ELM) mitigation has been achieved on MAST and AUG using resonant magnetic perturbations (RMPs) with various toroidal mode numbers over a wide range of low to medium collisionality discharges. The ELM energy loss and peak heat loads at the divertor targets have been reduced. The ELM mitigation phase is typically associated with a drop in plasma density and overall stored energy. In one particular scenario on MAST, by carefully adjusting the fuelling it has been possible to counteract the drop in density and to produce plasmas with mitigated ELMs, reduced peak divertor heat flux and with minimal degradation in pedestal height and confined energy. While the applied resonant magnetic perturbation field can be a good indicator for the onset of ELM mitigation on MAST and AUG there are some cases where this is not the case and which clearly emphasize the need to take into account the plasma response to the applied perturbations. The plasma response calculations show that the increase in ELM frequency is correlated with the size of the edge peeling-tearing like response of the plasma and the distortions of the plasma boundary in the X-point region. In many cases the RMPs act to increase the frequency of type I ELMs, however, there are examples where the type I ELMs are suppressed and there is a transition to a small or type IV ELM-ing regime.