A series of H-mode discharges have been conducted in the EAST tokamak to study the effect of divertor closure on divertor neutral distribution and edge plasmas by scanning the location of the outer strike point. When the outer strike point moves close to the corner within ∼, the gauge in upper sub-divertor shows that the neutral pressure increases, and the reciprocating probe at outer mid-plane indicates that electron temperature decreases and electron density increases in the scrape-off layer (SOL). In the meantime, the tungsten impurity concentration and radiation power in the main plasma decrease remarkably, while the main plasma density and stored energy increase slightly. SOLPS-ITER simulation without particle drifts is performed to better understand the impact of divertor closure. The simulation clearly demonstrates that a more closed divertor produces more neutrals around the corner with the increase of electron density and the decrease of electron temperature in the SOL, consistent with experimental results. Furthermore, more neutrals escape the divertor region and penetrate into the pedestal region, which induces more pedestal fuelling, increasing pedestal electron density. EAST will upgrade the lower divertor with a more closed geometry. These results provide important guidance for the upcoming upgrade.

已经在 EAST 托卡马克进行了一系列 H 模式放电，通过扫描外撞击点的位置来研究偏滤器闭合对偏滤器中性分布和边缘等离子体的影响。当外部打击点在 ∼ 内靠近拐角时, 上分流器中的压力表显示中性压力增加，外中平面的往复探针表明电子温度降低，电子密度增加在刮除层 (SOL) 中。同时，主等离子体中钨杂质浓度和辐射功率显着下降，而主等离子体密度和储存能量略有增加。执行无颗粒漂移的 SOLPS-ITER 模拟以更好地了解偏滤器闭合的影响。模拟清楚地表明，随着电子密度的增加和 SOL 中电子温度的降低，更封闭的偏滤器会在拐角处产生更多的中性点，这与实验结果一致。此外，更多的中性粒子逃离偏滤器区域并渗透到基座区域，这会引起更多的基座燃料，增加基座电子密度。EAST 将升级具有更封闭几何形状的下部偏滤器。这些结果为即将到来的升级提供了重要的指导。