Research and Development of a High Current Deuterium Negative Ion Source

强流氢/氚负离子源对聚变界来说是很有兴趣的，用于制备中性束流，即聚变等离子体的NBI加热。为此，我们从实验、理论和计算(即粒子模拟)三个方面研究了体积源中增强氢离子产生和氢离子提取的基本过程：(1)从理论上阐明了快电子e_f在氢离子产生过程中的作用。振动分子H_2^*对于H^-的产生是必不可少的。在一些H_2^*的生产过程中，e_f对H_2^*的碰撞激发是提高H^-产率的关键。(2)通过实验阐明了桶形源中等离子体栅势优化的H~+离子引出与等离子体参数的关系。(3)新设计了一种双等离子体类型的负离子源。在这个源中，通过改变两个等离子体之间的电势差，很好地控制了e_f的能量分布和它的量。实验上很好地证实了所谓的两步过程所引起的H^-离子的体积产生。(4)用二维静电粒子模拟研究了电子在磁过滤器中的能量依赖输运，并研究了H^-离子的引出。(5)产生了大量的氘等离子体，并引出了体积产生的D^-离子。同位素效应目前正在研究中。

High current hydrogen/deuterium negative ion sources are of interest to the fusion community for the preparation of neutral beams, namely NBI heating of fusion plasmas. To this end, basic processes for enhancement of H^- production and H^- extraction in volume sources have been studied experimentally, theoretically and computationally (i. e. particle simulation).(1) The role of fast electrons e_f in H^- production processes is well clarified theoretically. Vibrational molecules H_2^*, are essential to H^- production. Among some production processes of H_2^*, the collisional excitation of H_2^* by e_f is most important to enhance the H^- yield.(2) Relationship between extraction of H^- ions optimized by plasma grid potential and plasma parameters in a bucket source is clarified experimentally.(3) A double plasma type negative ion source is newly designed. In this source, the energy distribution of e_f and its quantity are well controlled by changing the potential difference between two plasmas. Volume production of H^- ions caused by the so-called two step process is well confirmed experimentally.(4) Two dimensional electrostatic particle simulation is implemented to study energy dependent electron transport across a magnetic filter, and to study extraction of H^- ions.(5) Deuterium plasmas are well produced, and volume produced D^- ions are extracted. Isotope effects are now under study.