The H-mode pedestal structure and its role on confinement in JET with a carbon and metal wall
The H-mode pedestal structure and its role on confinement in JET with a carbon and metal wall
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DOI：
10.1088/0029-5515/55/1/013019
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发表时间：
2013
期刊：
影响因子：
3.3
通讯作者：
M. Leyland;M. Beurskens;L. Frassinetti;C. Giroud;S. Saarelma;P. Snyder;J. Flanagan;S. Jachmich;M. Kempenaars;P. Lomas;G. Maddison;R. Neu;I. Nunes;K. Gibson
中科院分区：
文献类型：
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作者：
M. Leyland;M. Beurskens;L. Frassinetti;C. Giroud;S. Saarelma;P. Snyder;J. Flanagan;S. Jachmich;M. Kempenaars;P. Lomas;G. Maddison;R. Neu;I. Nunes;K. Gibson
本文介绍了在安装了新的ITER类壁（JET-ILW）后，由高分辨率汤姆逊散射测量确定的低和高三角度（δ = 0.22-0.39）2.5MA I型ELMy H模JET等离子体的基座结构。该数据库探讨了增加氘燃料和氮播种的影响，以解释观察到的性能变化（边缘和全球）。低三角形JET-ILW等离子体的性能和基座结构没有显着的变化与增加气体剂量。这些结果与EPED 1预测的结果非常一致。在高三角形，对于纯氘燃料的JET-ILW等离子体，与JET-C等离子体相比，整体性能和压力基座高度降低了20-30%。这种性能的降低主要是由于温度基座高度的降低。通过额外的氮气注入，JET-ILW等离子体的全球性能和压力基座高度可以部分恢复到JET-C等离子体的性能和压力基座高度（Giroud等人2013 Nucl. Fusion 53 113025）。这种观察到的性能改善主要是由于密度基座高度的显著增加以及温度基座高度的小幅增加。随着用于JET-ILW等离子体的氘燃料增加的关键结果是压力基座高度没有改善，但是基座仍然加宽，这与缩放不一致。此外，增加氮播种的关键结果是压力基座加宽是由于温度基座宽度的增加，而密度基座没有显示出明显的趋势。EPED 1预测与高三角形测量的比较是复杂的，例如，对于纯氘燃料等离子体，基座高度非常一致，但宽度不一致。此外，目前的EPED 1运行在JET-ILW等离子体的高氮籽晶下的基座高度和宽度预测不足，但是需要进一步的工作来确定这些偏差的重要性。了解这些偏差是必不可少的，因为它提供了对控制基座结构和边缘性能的物理机制的洞察。
We present the pedestal structure, as determined from the high-resolution Thomson scattering measurements, for a database of low and high triangularity (δ ≈ 0.22–0.39) 2.5 MA, type I ELMy H-mode JET plasmas after the installation of the new ITER-like wall (JET-ILW). The database explores the effect of increasing deuterium fuelling and nitrogen seeding with a view to explain the observed changes in performance (edge and global). The low triangularity JET-ILW plasmas show no significant change in performance and pedestal structure with increasing gas dosing. These results are in good agreement with EPED1 predictions. At high triangularity, for pure deuterium fuelled JET-ILW plasmas, there is a 20–30% reduction in global performance and pressure pedestal height in comparison to JET-C plasmas. This reduction in performance is primarily due to a degradation of the temperature pedestal height. The global performance and pressure pedestal height of JET-ILW plasmas can be partially recovered to that of JET-C plasmas with additional nitrogen seeding (Giroud et al 2013 Nucl. Fusion 53 113025). This observed improvement in performance is predominately due to a significant increase in density pedestal height as well as a small increase in the temperature pedestal height. A key result with increasing deuterium fuelling for JET-ILW plasmas is there is no improvement in pressure pedestal height however the pedestal still widens which is inconsistent with the scaling. Furthermore, a key result with increasing nitrogen seeding is the pressure pedestal widening is due to an increase in the temperature pedestal width whilst the density pedestal shows no clear trend. The comparison of EPED1 predictions with the measurements at high triangularity is complex as, for example, for pure deuterium fuelled plasmas there is very good agreement for the pedestal height but not the width. In addition, current EPED1 runs under-predict the pedestal height and width at high nitrogen seeding for JET-ILW plasmas however further work is required to determine the significance of these deviations. Understanding these deviations is essential as provides an insight to the physical mechanisms governing the pedestal structure and edge performance.