Study of hydrogen plasma affected by strong outer electric field

用二维粒子格子(PIC)方法计算了负离子源引出区势空间结构。证实了高束引出电压产生的引出电场通过束流引出孔侵入离子源等离子体。此外，还利用蒙特卡罗方法中的H^轨道计算方法计算了H^-引出概率。然后，根据PIC程序的计算结果，假定了H^-提取模型所需的势结构。用萃取模型计算的H^-萃取率与实验结果吻合较好。根据该模型的一些计算结果，我们得出结论：垂直于H^束轴方向的势能结构是从负离子源中引出H^的关键因素。

We calculate potential spatial structure at extraction region in a negative ion source with two dimensional Particle-In-Cell(PIC) method. It is confirmed that extraction electric field produced by high beam extraction voltage invades into the ion source plasma though a beam extraction hole. Besides, H^- extraction probability is calculated with H^- trajectory calculation in Monte Carlo method. Then, potential structure needed for the H^- extraction model is assumed by the calculation result of the PIC code. A calculation result with the extraction model is in good agreement with experimental result in H^- extraction probability. From some calculation results with the model, we conclude that potential structure for perpendicular direction to H^- beam axis is a key factor for H^- extraction from a negative ion source.