多峰场负氢离子源磁体布局对等离子体特性影响的数值模拟研究

负氢离子源的研究对于响应国家散裂中子源建设和国际热核聚变实验堆计划的开展都具有十分重要的意义. 由于离子源本身的物理特性导致数值模拟成为不可或缺的研究手段, 基于此, 首先对自主研发的全三维粒子模拟/蒙特卡罗碰撞算法进行阐述, 然后对负氢离子体积过程进行描述, 并在此基础上对中国原子能研究中心的多峰质子源进行了系统仿真, 在引出磁体极性相同和相反两种情形下, 分别对多峰质子源放电特性进行了讨论和分析. 结果显示: 在相反极性下, 两引出磁体附近的磁漂移方向相同且数值较大, 即磁漂移剧烈, 导致电子总数较大且高能电子在特定区域活跃, 进而负氢离子体积产率较高, 即负氢离子在空间呈现Y漂移; 反之, 在相同极性下, 电子约束效果相对较差且负氢离子体积产率较低, 但其空间分布均匀.

Numerical simulation research of plasma characteristics in a multi-cusp proton source based on magnets layout

It is significant to study negative hydrogen ion source for the construction of Chinese national spallation neutron source (CSNS) and the implementation of the international thermonuclear experimental reactor (ITER) project. Numerical simulation is an indispensable research measure due to the physical characteristics of ion source. In view of the facts above, in this paper we first elaborate the self-developed three-dimensional particle-in-cell/Monte Carlo collisions (PIC/MCC) algorithm and then describe the mechanism of negative hydrogen ion (H^-) volume production. Based on these, the multi-cusp proton source of the Chinese atomic energy research center is systematically simulated. In the cases of the same polarities and the opposite polarities of extraction magnetic fields, multi-cusp proton source discharge characteristics are discussed and analyzed respectively. The result shows that in the case of the opposite polarities of the two extraction magnets, magnetic drift directions near the two extraction magnets are the same and have great values, namely intense magnetic drift, which causes the total number of electrons to be big, and induces the high-energy electrons to become active in a specific area. And so, the volume production rate of H^- ions is higher, that is to say, H^- ions present Y drift. On the contrary, in the case of the same polarities of the two extraction magnets, the binding effect of electron is worse and the volume production rate of H^- ions is lower, but spatial distribution of volume production H^- is uniform.