Improvement of the Energy Stability of the Single Ion Microbeam

Energy instability strongly affects the state and the beam size of the single ion microbeam. A facility based on the Generating Voltmeter was developed to improve the energy stability of the CAS-LIBB （Chinese Academy of Sciences, key laboratory of ion beam bioengineering） single ion microbeam. This paper presents the analysis of the energy＇ instability of the single ion microbeam. A simplified theoretical model is set up to calculate the relationship between the energy instability and the beam spot size. By using this technique, the energy instability is adjusted to about 1%. Stable run-time is over 6 hours. The radius of the single ion beam is reduced by 10% compared to the previous olin.     

Characteristics of Ions Emitted from Laser-Induced Silver Plasma

In this work, study of laser-induced ions is presented. The plasma was produced by focusing a Nd：YAG laser, with a wavelength of 1064 nm, a pulsed width of 9-14 ns, a power of 1.1 MW and energy of 10 mJ, on silver target in vacuum （10-3 Torr= 1.3332 Pa）. The characteristics of ion streams were investigated by CR-39 detectors located at angles of 0°, 30°, 60° and 90° with respect to normal of the target. The distance between the silver target and each detector was 11 cm. The energy of silver ions was found ranging from 1.5 eV to 1.06E4 eV. There was a high concentration of ions with low energy as compared to those with high energy, showing the energy distribution amongst the ions. The flux of ions was maximum in the axial direction which was decreasing with the angle increase with respect to normal of the target, and finally became minimum in the radial direction. Hence the silver ions have shown anisotropic behaviour.     

GaAs基HEMT力敏结构伽马辐照损伤研究

利用60Co-γ射线对设计的GaAs基HEMT力敏结构进行了不同剂量的辐照,通过对辐照前后结构的电学特性、力敏特性分析对比,得到了γ辐照对力敏结构的损伤影响.与未辐照样品相比,90 MRad剂量辐照后HEMT力敏结构的漏极电流降低了约74％,辐照剂量高于100 MRad时,样品被击穿,失去工作特性.力敏特性测试结果表明...     

晶体管放大器静态工作点稳定性的判定方法

面对在几个稳定静态工作点的电路中选择时,如何迅速判定各电路静态工作点稳定性能的优劣,是一个值得弄清的重要问题。本文给出了求出典型放大器偏置电路的戴维南等效电路,依此等效电路可直接看清电路工作时的物理意义,进一步判定各个放大电路静态工作点稳定性能的优劣。     

SiC功率器件的研究和展望

分析了碳化硅(SiC)功率器件的研究现状与发展趋势,给出了在SiC功率整流二极管、SiC功率晶体管以及关键工艺中取得的最新研究成果.研制出了具有较好整流特性的SiC肖特基势垒二极管,并对其输运机理和高温特性进行了研究.研制成功了国内第一个SiC MPS二极管,耐压高达600V,正向电压为3.5V时电流密度可达1 000A/cm2.研制出国内第一个SiC MOSFET和第一个SiC BCMOSFET.所制备的SiC BCMOSFET可得到最高为90 cm2/(V·S)的有效迁移率.分析了界面态电荷和界面粗糙对SiC MOSFET反型层迁移率的影响,其结果对提高SiC MOSFET器件特性有一定指导作用.     

安徽南陵县三里矿区地表水化学特征及离子来源分析

为了解三里矿区地表水化学特征和离子来源,以期为矿区水资源的可持续利用提供理论基础。系统采取了三里矿区内河流、池塘和泉水水样共11个。运用Durov图、Gibbs图、离子比例系数图和多元统计分析对其水化学类型及离子来源进行解析。结果表明：研究区地表水的溶解性固体总量TDS平均值为123.36 mg/L,属淡水;pH平均值为8.40,呈弱碱性;Ca²⁺为优势阳离子,阴离子以HCO₃^-为主;由Durov图可知Ca-HCO₃型为研究区地表水的主要水化学类型;由Gibbs图和相关性分析以及离子比值分析可知三里矿区地表水中离子来源主要受水岩相互作用影响,受阳离子交替吸附、人为活动及矿区矿采活动影响较小;研究区地表水离子来源主要以碳酸盐岩风化溶解为主,兼有硅酸盐岩和硫酸盐岩的风化溶解影响。     

排水系统入海口新型消能工

通过实体模型试验研究了某排水系统入海口水工建筑物的水力性能,设计提出一种新型的墩栅涡流室消能工。该新型消能工的水力特点是:流出排水隧洞的高速水流大部分通过进口墩栅空隙流入涡流室,小部分在进口墩栅前发生水跃后扎入涡流室中产生强烈的顺时针漩涡,通过水跃、墩栅的阻力和涡流室漩涡的共同作用消能,并将来流的动能转换为势能,之后,涡流室中的大部分水流在重力作用下通过出口墩栅空隙流向下游,其余水流从墩栅顶部溢流。这种新型的墩栅涡流室不仅消能效果良好而且出流均匀,并容许各种杂物如石块、泥沙等自由通过,避免涡流室中发生严重的淤积。     

Zn2+-Al3+-LDHs@Al构建及其吸附氟离子的性能

以硝酸锌、硝酸铝为原料,尿素为沉淀剂,采用均相沉淀技术,在铝基体表面原位生长Zn2+-Al3+-LDHs薄膜.采用XRD、FT-IR、SEM和EDS等对铝片表面构建的Zn2+-Al3+-LDHs的成分和结构进行分析表征,研究表明,Zn2+-Al3+-LDHs膜均匀生长在铝基体表面,具有典型的LDHs材料的层状结构.研究...     

海堤加固中的钢筋混凝土栅栏板消浪机理及应用

该文以长乐国际机场海堤为例,分析钢筋混凝土栅栏板消浪机理和消浪效果,并根据工程实践,提出改进栅栏板结构建议。