Research and Development of a High Current Deuterium Negative Ion Source

强流氢/氘负离子源是聚变界感兴趣的中性束制备，即聚变等离子体的NBI加热。为此，已经从实验、理论和计算上研究了增强体积源中H^-产生和H^-提取的基本过程（即：e.粒子模拟）。(1)从理论上阐明了快电子e_f在H^-产生过程中的作用。振动分子H_2^* 对H^-的产生至关重要。在H_2^* 的产生过程中，电子对H_2^* 的碰撞激发是提高H_2^* 产率的重要途径。(2)通过实验研究了桶型源中等离子体栅电位优化的H^-离子引出与等离子体参数的关系。(3)设计了一种新型的双等离子体负离子源。在该源中，通过改变两个等离子体之间的电位差，可以很好地控制电场的能量分布及其大小。实验充分证实了由所谓的两步过程引起的H^-离子的大量产生。(4)利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^-离子的提取。(5)氘等离子体很好地产生，并且大量产生的D^-离子被提取。同位素效应正在研究中。

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.