淬火技术对酸洗法提纯多晶硅的催化作用

采用淬火技术和酸洗络合技术提纯多晶硅。采用ICP测试多晶硅纯度,采用XRD、红外光谱、拉曼光谱、扫描显微镜、扫描电镜和能谱技术分析淬火对多晶硅提纯的催化机理,结果表明:1)淬火能减弱多晶硅杂质元素与硅之间的键能和键力,使多晶硅晶体出现缺陷和缩小硅体晶面间距;2)多晶硅杂质相主要由非晶金属氧化物或金属硅化物构成;3)采用酸洗络合技术和二次凝固技术可使多晶硅中B的移除率达到90%,同时其他金属杂质的移除率均在55%以上,提纯硅的纯度基本满足太阳电池的需求。     

过渡金属掺杂单层MoS_2的第一性原理计算

利用基于密度泛函理论的第一性原理平面波赝势方法分别计算了本征及过渡金属掺杂单层MoS_2的晶格参数、电子结构和光学性质。计算结果显示,过渡金属掺杂所引起的晶格畸变与杂质原子的共价半径有联系,但并不完全取决于共价半径的大小。分析能带结构可以看到,Co、Ni、Cu、Tc、Re和W掺杂使能带从直接带隙变成了间接带隙。除了Cr和W以外,其它掺杂体系的禁带区域都出现了数目不等的新能级,这些杂质能级主要由杂质的d、S的3p和Mo的4d轨道组成。掺杂对MoS_2的光学性质也产生了相应的影响,使MoS_2的静态介电常数、介电函数虚部峰值、折射率和光电导率峰值呈现不同程度的增加。     

Simulations of Reversed Shear Configuration in EAST

The reversed shear （RS） mode is one of the advanced configurations being considered in EAST. Predictive simulations of EAST reversed shear configuration are carried out using an 1.5D equilibrium evolution code. In order to have the desired monotonic q-profile during a tokamak discharge, a successful preparation phase is required. In our simulation, the plasma current is ramped up from 100 kA to a fiat-top maximum of 1.0 MA for four seconds. An ICRH power of 1 MW is applied until the plasma shape is formed at the moment of 4 s, and then the power is raised to 3 MW. A LHCD power of 3.5 MW is applied from ls to optimize the plasma current density profile. A series of simulations are performed to study the influence of the time of applying the auxiliary heating on the plasma parameters. Based on these simulations, a scheme is proposed and tested for the control of the safety factor profile, which is very useful in real time profile control in tokamak experiments.