最近HL-2A已经初步实现H模条件下的偏滤器部分脱靶运行，同时发现脱靶对极向SOL流有重要影响。而且，HL-2A实验还显示平均压强梯度所驱动的流对H模的产生有关键影响，AUG装置也发现压强梯度所驱动的等离子体流对剪切流有重要作用。这都表明，偏滤器脱靶会对SOL流及H模约束产生重要影响。虽然国内外都意识到了这个问题的重要意义，但由于目前国际上主要托卡马克装置偏滤器位形的限制，难以有效进行相关研究。比如DIII-D已经在H模放电时通过充气实现部分脱靶。但由于其偏滤器的开放性，对主等离子体有较大影响，无法充分研究其对SOL流及约束的影响。而本课题就是利用HL-2A装置独有的封闭式偏滤器，它能够避免偏滤器充气和脱靶对主等离子体的影响，利用这种独特优势，实现不同程度偏滤器脱靶与H模的共同运行，研究脱靶对极向SOL流的影响以及对H模约束的间接影响，并对偏滤器脱靶运行是否对H模约束具有改善作用进行评估。

The partial detachment under the H mode confinement has been carried out recently in the HL-2A tokamak, and it is found that divertor detachment has an important effect on the poloidal SOL flow. Moreover, previous HL-2A experiments indicate that flow driven by mean pressure gradient has critical influence on the creation of the H-mode. The results on ASDEX-U also present that the flow driven by pressure gradient has a strong impact on the shear flow. All of the statements above imply that the detachment could have important effects on the poloidal SOL flow and the H mode confinement. Although the importance of the issue has been recognized, it is very hard to be investigated due to the divertor configurations of current tokamaks over the world. For example, although the partial detachment with H mode has been implemented on DIII-D, it is impossible to investigate the effect of detachment on the SOL flow and H mode confinement due to its open divertor structure. The divertor gas puffing may strongly influence on the main plasma when the gas is puffed into the divertor region. In this project, due to the unique closed divertor configuration of HL-2A, the effect of detachment on the poloidal SOL flow and the H mode confinement can be studied in HL-2A. Then it can be evaluated if the detachment is good or bad for the H mode confinement, which is very important for the operation scenario of ITER and future fusion reactors.