ELM moderation with ICRF heating on JET
ELM moderation with ICRF heating on JET
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DOI：
10.1088/0741-3335/44/9/312
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发表时间：
2002-08
影响因子：
2.2
通讯作者：
G. Maddison;J. Snipes;J. Chareau;G. Conway;I H Hutchinson;L. Ingesson;H. Koslowski;A. Loarte;P. Lomas;M. Mantsinen;G. Matthews;L. Meneses;M. Nave;E. Righi;G. Saibene;R. Sartori;O. Sauter;K. Zastrow;Contributors to EFDA-Jet Workprogramme
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文献类型：
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作者：
G. Maddison;J. Snipes;J. Chareau;G. Conway;I H Hutchinson;L. Ingesson;H. Koslowski;A. Loarte;P. Lomas;M. Mantsinen;G. Matthews;L. Meneses;M. Nave;E. Righi;G. Saibene;R. Sartori;O. Sauter;K. Zastrow;Contributors to EFDA-Jet Workprogramme
在Alcator C-Mod器件上，通过欧姆或射频加热，展示了高密度、无elm、“增强型alpha”（EDA） h模式。先前在JET上的“Mk0”分流器实验中也观察到一个相关的“低粒子约束”h态。据报道，在JET ‘MkIIGB’分流器配置中，采用适当形状的磁平衡，初步尝试恢复类似的状态。在有和没有分流器冷泵的情况下的比较表明，增强的边缘源倾向于增加ELM频率并减小其尺寸，而不会降低约束。然而，由于JET的下壁循环，环面压力仍然低于C-Mod。在低温泵浦的作用下，离子回旋共振加热（ICRH）主导的联合加热可能适合于最大的磁流体动力学稳定性，导致反复出现无elm的h模相位。在每个无elm相中，随着密度和边缘辐射的增加，堆芯约束达到峰值，而在它们之间只出现小的复合elm。此外，每个静息期的磁和密度波动集中在两个频率附近，尽管这些模式似乎与C-Mod上EDA期间看到的相干模式相反方向旋转。在最新和更早的LPCH JET病例中，基座碰撞率也要低得多。最后，在相同密度和功率下的不同h模式表明了加热方案本身对边缘特性的影响，ICRH比NBH出现更低的基座电子温度和更高的ELM频率。无量纲等离子体变量的更接近匹配将阐明eda模式的可扩展性及其作为下一步综合机制的潜力。
A high-density, ELM-free, 'enhanced Dalpha' (EDA) H-mode has been demonstrated with Ohmic or RF heating on the Alcator C-Mod device. An allied 'low particle confinement' H-regime was also observed previously in 'Mk0' divertor experiments on JET. Initial attempts to recover similar states in the JET 'MkIIGB' divertor configuration are reported, employing appropriately shaped magnetic equilibria. Comparisons between cases with and without divertor cryopumping show enhanced edge sources tend to increase ELM frequency and reduce their size, without degrading confinement. However, torus pressure remains below that in C-Mod owing to lower wall recycling in JET. With cryopumping on, ion cyclotron resonance heated (ICRH)-dominated combined heating may be adapted for maximum magnetohydrodynamic stability, leading to recurrent ELM-free H-mode phases. Core confinement peaks as density and edge radiation rise in each ELM-free phase, while only small compound ELMs occur between them. Moreover magnetic and density fluctuations in each quiescent period are concentrated around two frequencies, although these modes appear to rotate in the opposite direction to coherent modes seen during EDA on C-Mod. Pedestal collisionality also remains much lower in both latest and even earlier LPCH JET cases. Finally an effect of heating scheme itself on edge properties is indicated by alternative H-modes at the same density and power, with lower pedestal electron temperature and higher ELM frequency occurring for ICRH than for NBH. Closer matches in dimensionless plasma variables would clarify scalability of EDA-mode and its potential as an integrated next-step regime.