3D edge transport analysis of ITER start-up configuration for limiter power load assessment
3D edge transport analysis of ITER start-up configuration for limiter power load assessment
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DOI：
10.1088/0029-5515/47/2/001
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发表时间：
2007-01
期刊：
影响因子：
3.3
通讯作者：
M. Kobayashi;Y. Feng;A. Loarte;G. Federici;G. Strohmayer;M. Shimada;F. Sardei;D. Reiter;M. Sugihara
中科院分区：
文献类型：
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作者：
M. Kobayashi;Y. Feng;A. Loarte;G. Federici;G. Strohmayer;M. Shimada;F. Sardei;D. Reiter;M. Sugihara
利用三维边缘输运程序EMC 3-EIRENE对ITER启动阶段环形离散限制器构型的边缘输运特性进行了分析。由于边缘中的有限磁剪切，限制器与不同q值的通量表面的相互作用在连接长度（LC）分布中引入了复杂的3D图案，其中长通量管和短通量管共存于刮除层中。与边缘中的非常长的通量管相关的问题的严重性（其可能带来大量能量（与LC的平方根成比例）并在限制器上引起热点）得到缓解，并且没有发现显著的局部功率负载。(i)对于长通量管，垂直能量传输时间变得比平行能量传输时间短，导致没有净能量输入到通量管。(ii)Percular运输被认为是非常有效的涂抹出的各种通量管进行的平行的能量通量的差异，如果它们相互作用在一个垂直的运输规模，约几厘米，这通常是在高等离子体电流ITER启动配置的情况下。这两种效应显著降低了能量沉积对LC的依赖性。在高等离子体电流（例如6.5MA）下，发现峰值功率负载接近工程极限，特别是对于最低的垂直输运系数和最高的输入功率。将3D建模的结果与径向指数衰减模型进行比较，发现通过忽略3D几何效应，简单模型对于相应的输入功率和能通量的径向衰减高估了峰值功率负载约30%。
The edge transport properties of the toroidally discrete limiter configuration in the ITER start-up phase has been analysed, using the 3D edge transport code, EMC3-EIRENE. Because of the finite magnetic shear in the edge, the interaction of the limiters with flux surfaces of different q-values introduces a complex 3D pattern in the connection length (LC) profiles, where long and short flux tubes co-exist in the scrape-off layer. The severity of problems associated with very long flux tubes in the edge, which could bring a large amount of energy (proportional to the square root of LC) and cause a hot spot on the limiter, was mitigated and no significant localized power load was found. This can be justified as follows. (i) For long flux tubes, the perpendicular energy transport time becomes shorter than the parallel energy transport time, resulting in no net energy input to the flux tube. (ii) Perpendicular transport was found to be very effective to smear out the difference in the parallel energy flux conducted by the various flux tubes, if they interact within a perpendicular transport scale, about a few cm, which is usually the case in high plasma current ITER start-up configuration. These two effects significantly reduce the dependence of energy deposition on LC. At the high plasma current (e.g. 6.5 MA), the peak power load is found to be close to the engineering limit, especially for lowest perpendicular transport coefficients and the highest input power. Comparing the results of the 3D modelling with a radial exponential decay model, it was found that by neglecting the 3D geometrical effects, the simple model overestimates the peak power load by ∼30% for corresponding input power and radial decay of energy flux.