Computer Simulation of Plasma-Surface Interactions in Fusion Devices

处理磁约束聚变装置中导流板等离子体-表面相互作用的计算机模拟程序。该模拟代码允许同时入射不同的离子种类以及麦克斯韦速度分布和离子的不同电荷状态。离子注入和释放的杂质在边缘等离子体中的电离和回旋运动导致的再沉积导致的表层动态组成变化。利用该模拟程序研究了托卡马克TEXTOR-94中W试验限制器暴露于含有杂质C和O的氘边等离子体中的粒子释放。迅速的再沉积强烈抑制了W杂质从限制器的释放，而低Z杂质（C和O）的影响要小得多。在限制器前，专家观察到的WI和CII线强度的径向分布可以用W和沉积的C的物理溅射以及杂质的高能反射来解释。另一方面，作为限制器的石墨前面的CII线发射归因于D离子冲击化学溅射导致的许多低能原子，而高z杂质（如w）的沉积强烈抑制了D离子的溅射，并通过模拟研究了暴露于氘边缘等离子体的薄膜中硼的侵蚀和同时在TEXTOR-94中的碳沉积。碳杂质的注入奇怪地改变了薄膜的有效硼溅射收率，降低了薄膜的侵蚀，形成了厚的碳沉积。实验观察到的比尔线发射在远离等离子体边缘的表面附近的强烈下降可以用薄膜上的碳沉积来解释。计算得到的模膜碳深度分布与原子发射光谱测量结果吻合较好。为了分析磁聚变装置壁上形成的鞘层电压与固体二次电子发射的关系，对等离子体鞘层中二次电子的输运进行了联合蒙特卡罗模拟。少

A computer simulation code which treats plasma-surface interactions for divertor plates in magnetic confine-went fusion devices. The simulation code allows simultaneous incidence of different ion species as well as a Maxwellian velocity distribution and different charge states of the ions. The dynamic composition change of the surface layer due to ion implantation and redeposition of released impurities due to their ionization and gyromotion in an edge plasma.Particle release from a W test limiter exposed to deuterium edge plasma, containing impurities C and O, in the tokamak TEXTOR-94 is studied by using this simulation code. The release of W impurities from the limiter is strongly suppressed by prompt redeposition, whereas low Z impurities (C and O) are much less influenced. Expert- mentally observed radial distributions of WI and CII line intensities in front of the limiter can be explained by physical sputtering of W and deposited C, in addition to high-energy reflection of impurit … More y C ions. On the other hand, the CII line emission observed in front of graphite as a limiter is attributed to many low-energy atoms due to chemical sputtering by impact of D ions, which is strongly suppressed by deposition of high-Z impurities, such as W.Erosion of boron out of a thin film exposed to deuterium edge plasmas and the simultaneous carbon deposition in TEXTOR-94 is studied by simulation. The implantation of carbon impurities strangly changes the effective boron sputtering yield of the film, which results into a lowering of the film erosion and a formation of thick carbon deposits. A strong decrease in the experimentally observed Bill line emission around a surface location far from the plasma edge can be explained by a carbon deposition on the film. The cauculated carbon depth proflies in die film are in resonable agreement with measurements by AES.A combined Monte Carlo simulation of secondary electron emission from solids and transport of secondary electrons in a plasma sheath is performed for analyzing a relationship between the secondary electron yield and sheath voltage formed on the wall in magnetic fusion devices. Less