Abstract: In order to improve the charging depth and efficiency of pellets in HL-2A tokamak, an original encapsuled pellet injection fueling was recently developed. Neglecting the ablation process of the non-fuel cladding of the encapsuled pellet, the transport characteristics of the new encapsuled pellet deposited at the position of radial normalized magnetic flux equaling to 0.9 and the self-consistent interaction with the background plasma are simulated in two dimensions with Trans-neut code under HL-2A tokamak configuration. The evolutions of charging particles and background plasma profile are given. The results show that deuterium ions deposit and peak in the radial inside of feeding position, and the core density increases continually under the radial diffusion. The regions of ion temperature and electron temperature reduction at fueling position expand continually during the fueling. The evolution of electron temperature profile in poloidal direction is faster than that of ion temperature profile. The normalized molecular density and radial distribution width at feeding position decrease first and then increase, which is negatively correlated with that of the molecular decomposition at the feeding place.

Key words: Tokamak plasma, Encapsuled pellet, Numerical simulation, Profile evolution

摘要： 为了提高 HL-2A 等离子体中弹丸加料深度和加料效率，研制了新型充气弹丸注入加料方法。忽略 充气弹丸非加料包层的烧蚀过程，在 HL-2A 托卡马克位形下，应用 Trans-neut 程序对沉积在径向归一化磁通ψ=0.9 位置处的充气弹丸输运特性及其与本底等离子体自洽的相互作用过程进行了二维数值模拟研究，给出了加料粒子 和本底等离子体剖面的时空演化。发现氘离子在弹丸加料位置的径向内侧沉积、峰化，在径向扩散作用下，芯部 密度不断增加。在加料期间，加料点的离子温度和电子温度降低的区域不断扩展，电子温度剖面在极向上的演化 过程要快于离子温度剖面的演化过程。弹丸沉积位置的归一化分子数密度和径向分布宽度先减小后增加，与加料 处的分子分解源项(即分子密度损失率)先增加而后减小呈负相关。

关键词: 托卡马克等离子体；充气弹丸；数值模拟；剖面演化