Numerical analysis of tungsten erosion and deposition processes under a DEMO divertor plasma and geometry
Numerical analysis of tungsten erosion and deposition processes under a DEMO divertor plasma and geometry
复制标题
DEMO 偏滤器等离子体和几何形状下钨侵蚀和沉积过程的数值分析
DOI：
10.1016/j.nme.2017.05.003
复制
发表时间：
2017
影响因子：
2.6
通讯作者：
Y.Homma ,K.Hoshino,S.Yamoto ,N.Asakura S.Tokunaga ,A.Hatayama,Y.Sakamoto,R.Hiwatari ,K.Tobita ,DEMO Joint Special Design Team for Fusion
中科院分区：
文献类型：
--
作者：
Y.Homma ,K.Hoshino,S.Yamoto ,N.Asakura S.Tokunaga ,A.Hatayama,Y.Sakamoto,R.Hiwatari ,K.Tobita ,DEMO Joint Special Design Team for Fusion
由于偏滤器靶在长达一年的运行期内要承受大注量的入射粒子（主要由燃料离子和籽晶杂质组成）的侵蚀，因此减小偏滤器靶的侵蚀是DEMO聚变堆设计的重要研究课题之一。利用SOL/偏滤器等离子体集成程序SONIC和动力学全轨道杂质输运程序IMPGYRO研究了偏滤器外靶的净烧蚀和沉积速率。采用了两种背景等离子体：一种是低密度ni和高温情况，另一种是高ni和低温情况。净侵蚀已被视为在较低的n-i的情况下。但在高ni的情况下，由于返回率的增加和自溅射产额的降低，净侵蚀几乎被抑制。以下两个因素对于理解净侵蚀的形成是重要的：（i）溅射的W原子的第一电离长度与W+离子的Larmor陀螺半径的比率;（ii）施加在W离子上的摩擦力和热作用力之间的平衡。演示偏滤器的设计应考虑到这些因素，以防止靶侵蚀。
Erosion reduction of tungsten (W) divertor target is one of the most important research subjects for the DEMO fusion reactor design, because the divertor target has to sustain large fluence of incident particles, composed mainly of fuel ions and seeded impurities, during year-long operation period. Rate of net erosion and deposition on outer divertor target has been studied by using the integrated SOL/divertor plasma code SONIC and the kinetic full-orbit impurity transport code IMPGYRO. Two background plasmas have been used: one is lower density n i and higher temperature case and the other is higher n i and lower temperature case. Net erosion has been seen in the lower n i case. But in the higher n i case, the net erosion has been almost suppressed due to increased return rate and reduced self-sputtering yield. Following two factors are important to understand the net erosion formation:(i) ratio of the 1st ionization length of sputtered W atom to the Larmor gyro radius of W+ ion,(ii) balance between the friction force and the thermal force exerted on W ions. DEMO divertor design should take into account these factors to prevent target erosion.