中文摘要：

利用具有定向速度的超声分子束注入技术，研究了HL-2A装置在较低加热功率条件下实现L_H转换的等离子体放电特征，从边缘密度分布的差异比较分析了普通送气和超声分子束注入对L-H转换的影响．实验结果表明，HL-2A装置上采用超声分子束注入可直接触发L-H转换，明显降低L-H转换功率．通过对大量实验数据的分析和整理发现，利用超声分子束注入实现L-H转换的最低加热功率，比同等条件下采用普通送气实现L-H转换的最低加热功率减少约10％．

英文摘要：

Features of L-H transition are investigated using the supersonic molecular beam injection （SMBI） with directional velocity under low heating powers in the present paper. Comparing the edge density profiles, it is analyzed that the conventional gas puffing （GP） and SMBI have effects on L-H transition. Experimental results suggest that the SMBI does directly trigger L-H transition on HL-2A, and it considerably reduces the power threshold of L-H transition. After abundant experimental data are analyzed and processed, it is found that the minimum L-H transition power with SMBI decreases by 10% when it is compared with GP trigged H-mode under same conditions.