封闭偏滤器靶板热通量沉积宽度的定标关系研究

The scaling law of heat flux width deposited on divertor plates is one of frontier topics in the researches of magnetic confinement fusion. It is inversely proportional with poloidal magnetic field approximately to have been observed in some open divertor tokamaks. This project is going to investigate the scaling law of heat flux width in a closed divertor tokamak. At first, we shall confirm whether the scaling law is reversly proportional with the poloidal magnetic field or not. Next, we will focus on the scaling law of heat flux width versus the connection length of magnetic field line, upstream boundary density, power into scrape off layer, and power loss fraction on divertor plate. Experimental results will be compared with theoretical ones. This study may provide the useful tool for predicting the heat flux width of next generation tokamaks, such as ITER. This project is planned to improve two infrared impaging diagnostics with toroidal separation about 100 degree, which have the spatial resolution of 0.9 mm in the range of 15 cm, and temporal resolution of 0.1 ms. Two sets of triple probe arrays fixed on divertor targets will be developed, which have toroidal separation about 170 degree, spatial resolution of 6 mm in vertical range of 12 cm, and temporal resolution of 1 microseconds. After many data being acquired, regression analyses will be applied to obtain the scaling law of heat flux width versus plasma parameters mentioned as above. In addition, we shall also explore the influence of MHD instabilities and disruptions on the scaling laws of heat flux width by using the mass impurity injection into main plasma.

偏滤器靶板上热通量沉积宽度的定标关系是磁约束受控聚变研究的前沿课题之一，在一些开放偏滤器上已经观测到该宽度与极向磁场近似成反比。本项目拟在封闭偏滤器上开展热通量宽度的定标关系研究，首先验证它是否与极向磁场成反比；然后，重点研究该宽度与磁力线连接长度、上游边界密度、刮削层功率、靶板上的功率损失份额的定标关系，并与理论预测结果进行比对，为预测下一代聚变装置如ITER的热通量宽度提供参考依据。完善偏滤器室内两个环向相距约100度的红外成像诊断，它们在靶板上15cm内的空间分辨是0.9mm，时间分辨0.1ms；其次是建设两套环向相距约170度的偏滤器靶板固定三探针阵列，它们在12cm内的空间分辨是6mm，时间分辨1微妙。在获取大量实验数据后，利用回归分析方法获取热通量宽度与上述等离子体参数的定标关系。此外，拟在主等离子体注入大量杂质，探索研究磁流体不稳定性和破裂如何影响热通量宽度的定标关系。

偏滤器靶板上热通量沉积宽度的定标关系是磁约束受控聚变研究的前沿课题之一，在一些开放偏滤器上已经观测到该宽度与极向磁场近似成反比。本项目在封闭偏滤器上开展热通量宽度的定标关系研究，验证了它也与极向磁场近似成反比。然后，重点研究该宽度与磁力线连接长度或者安全因子、上游边界密度或者线平均电子密度、刮削层功率的定标关系，并与理论预测结果一致，为预测下一代聚变装置如ITER的热通量宽度提供参考依据。完善了偏滤器室内两个环向相距约120度的红外成像诊断系统，它们在靶板上15 cm内的空间分辨为0.9 mm，时间分辨为2 kHz，最高可以达到10 kHz；其次是建设了两套环向相距约170度的偏滤器靶板固定三探针阵列，它们在12 cm内的空间分辨是6 mm，时间分辨1微妙。在获取大量实验数据后，利用回归分析方法研究了热通量宽度与等离子体电流、安全因子、密度和刮削层功率的定标关系。.利用国际上通用的方法，统计分析了封闭偏滤器上靶板热通量宽度与等离子体参数之间的定标关系。通过大量分析实验结果，选择相同或相似实验条件的放电参数后，完成了在欧姆、L-模和H-模三种运行模式下靶板热通量宽度与等离子体参数的定标关系研究。回归分析结果表明，靶板热通量宽度与等离子体电流和刮削区的功率存在很强的负相关关系；与环向磁场和等离子体密度的关系则比较弱；与安全因子q95近似成正比。这些定标结果与两点理论模型的预测相符，并与开放偏滤器装置上的实验结果基本一致。但是，封闭偏滤器在隐蔽通量区的传播宽度S比开放偏滤器要大，它与热通量宽度之间的关系也要比开放偏滤器更强。.此外，实验研究表明湍流输运可以拓宽刮削层宽度，它随着边缘和刮离层的相对密度扰动、归一化湍流内能、湍流粒子通量以及粒子输运系数增大而增大；刮削层宽度随着最大径向电场及其剪切率增加而减小。边缘区湍流和刮削层湍流通过湍流能量非线性传播相互耦合，而刮削层宽度与湍流能量非线性传播正相关。