Analysis of pedestal plasma transport
Analysis of pedestal plasma transport
复制标题
DOI：
10.1088/0029-5515/50/6/064004
复制
发表时间：
2010-06
期刊：
影响因子：
3.3
通讯作者：
James D. Callen;R. Groebner;T. Osborne;John Canik;L. Owen;A. Pankin;T. Rafiq;T. Rognlien;W. Stacey
中科院分区：
文献类型：
--
作者：
James D. Callen;R. Groebner;T. Osborne;John Canik;L. Owen;A. Pankin;T. Rafiq;T. Rognlien;W. Stacey
对一个DIII-D基座进行了H模式边缘基座等离子体输运基准测试。所使用的运输模型代码包括1.5D解释代码（ONETWO、GTEDGE）、1.5D预测代码（ASTRA）和2D代码（SOLPS、UEDGE）。所考虑的特定DIII-D放电是98889，其具有典型的低密度基座。边缘等离子体的配置文件，从汤姆逊和电荷交换复合数据平均超过最后20%的平均33.53毫秒的重复时间之间的I型边缘本地化模式。模拟的再循环中性粒子密度在偏滤器X点区域最大，并导致边缘等离子体源速率在分界线上变化因子为102。通量表面上密度和温度的模拟极向变化在所有通量表面上都很小，直到中面分界线的大约2.6 mm（ρN > 0.99）以内。对于假定的菲克扩散型定律，径向热量和密度通量在基座区域以2-3的因子极向变化;它们在通量表面被压缩的外侧中平面上最大，局部径向梯度最大。对流热流被发现是小部分的电子（约10%）和离子（约25%）的热流在这个基座。适当平均的传输通量产生解释1.5D有效扩散系数是最小的基座的中点附近。它们的“传输势垒”最小值约为0.3（电子热）、0.15（离子热）和0.035（密度）m2 s−1。电子热传输被认为是最好的特点是电子温度梯度诱导的运输在基座顶部和整个基座的古古典运输。基座中的有效离子热扩散率具有与新古典预测不同的轮廓，并且可能小于它。非常小的有效密度扩散率可能是向内夹点流几乎平衡扩散向外径向密度通量的结果。向内的离子夹点速度和密度扩散系数是由一个新的解释分析技术，使用的信息从力平衡（动量守恒）方程;古经典运输模型提供了一个合理的解释这些新的结果。最后，测量和额外的建模需要更好地促进基座等离子体传输建模进行了讨论。
An H-mode edge pedestal plasma transport benchmarking exercise was undertaken for a single DIII-D pedestal. Transport modelling codes used include 1.5D interpretive (ONETWO, GTEDGE), 1.5D predictive (ASTRA) and 2D ones (SOLPS, UEDGE). The particular DIII-D discharge considered is 98889, which has a typical low density pedestal. Profiles for the edge plasma are obtained from Thomson and charge-exchange recombination data averaged over the last 20% of the average 33.53 ms repetition time between type I edge localized modes. The modelled density of recycled neutrals is largest in the divertor X-point region and causes the edge plasma source rate to vary by a factor ∼102 on the separatrix. Modelled poloidal variations in the densities and temperatures on flux surfaces are small on all flux surfaces up to within about 2.6 mm (ρN > 0.99) of the mid-plane separatrix. For the assumed Fick's-diffusion-type laws, the radial heat and density fluxes vary poloidally by factors of 2–3 in the pedestal region; they are largest on the outboard mid-plane where flux surfaces are compressed and local radial gradients are largest. Convective heat flows are found to be small fractions of the electron (≲10%) and ion (≲25%) heat flows in this pedestal. Appropriately averaging the transport fluxes yields interpretive 1.5D effective diffusivities that are smallest near the mid-point of the pedestal. Their ‘transport barrier’ minima are about 0.3 (electron heat), 0.15 (ion heat) and 0.035 (density) m2 s−1. Electron heat transport is found to be best characterized by electron-temperature-gradient-induced transport at the pedestal top and paleoclassical transport throughout the pedestal. The effective ion heat diffusivity in the pedestal has a different profile from the neoclassical prediction and may be smaller than it. The very small effective density diffusivity may be the result of an inward pinch flow nearly balancing a diffusive outward radial density flux. The inward ion pinch velocity and density diffusion coefficient are determined by a new interpretive analysis technique that uses information from the force balance (momentum conservation) equations; the paleoclassical transport model provides a plausible explanation of these new results. Finally, the measurements and additional modelling needed to facilitate better pedestal plasma transport modelling are discussed.