Computer Simulation of Plasma-Surface Interactions in Fusion Devices

一种计算机模拟代码，用于处理磁约束聚变装置中偏滤器板的等离子体-表面相互作用。模拟程序允许不同离子物种的同时入射，以及离子的麦克斯韦速度分布和不同的电荷状态。利用该程序研究了离子注入和边缘等离子体中释放的杂质的电离和回旋运动引起的表面层成分的动态变化。利用该模拟程序研究了托卡马克TEXTOR-94装置中W试验限制器在含有杂质C和O的氦边缘等离子体中的粒子释放。W杂质从限制器中的释放受到快速再沉积的强烈抑制，而低Z杂质(C和O)的影响要小得多。除了杂质…的高能反射外，专家观察到的限幅器前W和C的径向强度分布可以用W和沉积的C的物理溅射来解释更多的Y-C离子。另一方面，在作为限制器的石墨前面观察到的CII线发射是由于D离子的碰撞而引起的化学溅射导致的许多低能原子，而高Z杂质的沉积强烈地抑制了这种低能原子的沉积，例如W。模拟研究了薄膜中的硼在氚边缘等离子体中的腐蚀和在TEXTOR-94中同时的碳沉积。碳杂质的注入奇特地改变了薄膜的有效硼溅射产额，从而降低了薄膜的烧蚀量，并形成了厚的碳层。实验观察到的远离等离子体边缘的表面位置附近的比尔谱线发射的强烈减少可以用薄膜上的碳沉积来解释。用蒙特卡罗方法对固体二次电子发射和等离子体鞘内二次电子输运进行了联合蒙特卡罗模拟，分析了磁聚变装置中二次电子产额与鞘电压之间的关系。较少

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