Abstract—

The dissipative divertor for the power and particle exhaust in a tokamak relies heavily on strong impurity radiation inside the divertor volume. In the present paper, the influence of the cross-field transport inside the divertor volume on the radiation loss by nitrogen and neon impurity seeding is studied in the SOLPS4.3 2D transport code. The study is carried out in a simplified tokamak geometry with long divertor legs, aimed at amplifying the effect of impurity radiation. It is shown that despite the simple analytical models predicting the enhancement of the low-Z impurity radiation loss with increasing cross-field heat conduction inside the divertor volume, the detailed 2D simulations demonstrate such a trend only if the electron density at the separatrix is used as the principal parameter quantifying the density of the edge plasma. However, if the total amount of the hydrogen isotope particles, which is a more suitable parameter for the edge plasma characterization, is considered, then the cross-field transport shows practically no impact on the impurity radiation in the divertor. It is found also that for a fixed ratio of the impurity to the main plasma content in the edge, two stable solutions can exist in a rather wide interval of the densities of the edge plasma. These solutions are attributed to the different distributions of the seeded impurity between the outer and inner divertors. Jumps between these two stable branches may result in bifurcation-like transitions between the attached and detached divertor regimes.

中文翻译：

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转移器中的跨场传输对种子杂质辐射和转移器等离子体分离的影响

摘要-

托卡马克中动力和颗粒排放的耗散偏滤器在很大程度上依赖于偏滤器内部的强杂质辐射。在本文中，在SOLPS4.3 2D传输代码中研究了偏滤器体积内的交叉场传输对氮和氖杂质播种对辐射损失的影响。这项研究是在简化的托卡马克几何结构和较长的偏斜腿上进行的，旨在放大杂质辐射的影响。结果表明，尽管简单的分析模型预测了低Z值的增强，杂质辐射损失随着偏滤器体积内部交叉场热传导的增加而增加，详细的2D模拟仅在将分离线处的电子密度用作量化边缘等离子体密度的主要参数时才显示出这种趋势。但是，如果考虑到氢同位素颗粒的总量（这是更适合边缘等离子体表征的参数），则交叉场传输实际上对分流器中的杂质辐射没有影响。还发现，对于边缘中杂质与主要等离子体含量的固定比率，可以在边缘等离子体的密度的相当宽的间隔中存在两种稳定溶液。这些解决方案归因于外部和内部分流器之间的晶种杂质分布不同。