通用电子测量仪器自动测量系统的实现

现如今通用电子测量仪器具备了更宽的测量范围和更高的测量精度,因此通过构建基于这些仪器的自动测量系统来进一步提升测量效率就显得十分必要。以Agilent公司生产的E5072A矢量网络分析仪为例,利用LabVIEW开发平台和SCPI命令,构建了E5072A的自动测量系统。该系统能够极大的提高测量效率,移植性好,可以胜任一些耗时长、需定时测量等较繁复的测量工作。     

Commissioning of electron cooling in CSRe

The 400 MeV/u 12C6＋ ion beam was successfully cooled by the intensive electron beam near 1 A in CSRe.The momentum cooling time was estimated near 15 s.The cooling force was measured in the cases of difierent electron beam profiles,and the difierent angles between the ion beam and electron beam.The lifetime of the ion beam in CSRe was over 80 h.The dispersion in the cooling section was confirmed as positive close to zero.The beam sizes before cooling and after cooling were measured by the moving screen.The beam diameter after cooling was about 1 mm.The bunch length was measured with the help of the signals from the beam position monitor.The difiusion was studied in the absence of the electron beam.     

输出2TW/45fs的掺钛蓝宝石超短脉冲强激光系统

建立了一套基于啁啾脉冲放大技术,输出峰值功率达到2.8TW的掺钛蓝宝石激光系统。压缩脉冲的中心波长为785nm,能量为120mJ,脉冲宽度43.3fs,能量稳定性±5%,输出的光束质量M~2<1.5,脉冲重复频率10Hz,运转稳定可靠。整套激光系统实现了小型化,占用的光学平台不足10m²。     

HIRFL-CSR主环电子冷却模拟计算

以¹⁶O⁸⁺为例,用电子冷却模拟程序计算了冷却时间随离子能量、初始发射度、初始动量分散、离子流强以及离子电荷态的变化规律,研究了储存环在冷却段的β函数和色散函数对冷却时间的影响.     

HIRFL—CSR实验环电子冷却装置调试

HIRFL-CSR实验环电子冷却装置采用了能够产生空心电子束的电子枪。弯曲螺线管内采用了静电偏转电极，冷却段采用了独立的高精度螺线管串联产生纵向磁场的设计。测量了沿离子束运动方向冷却段磁场分布及磁场平行度、电子枪和收集器性能、300kV高压电源相关参数。结果表明，此装置达到了预期的设计目标。: In CSRe electron cooling device， a special electron gun which can produce variable profile electron beam with different size and density distribution was adopted for decreasing ion losses. Electrostatic bending device was used for reducing electron beam losses and improving vacuum condition. The instability of the electron beam is suppressed because the secondary electrons from collector would come back to the collector in the same orbit finally. Longitudinal magnetic field with parallelism better than 10-4 was achieved by adopting of independent high precise solenoid coils at cooling section. In this case， the r.m.s deviations of the transverse magnetic field at cooling section in horizontal and vertical direction are 3.298×10-5 and 2.458×10-5 respectively. The characters of the gun and collector were investigated. The results were presented and indicate that it achieves the design purpose very well.     

Longitudinal Schottky spectra of a bunched Ne10+ ion beam at the CSRe

The longitudinal Schottky spectra of a radio-frequency (RF) bunched and electron cooled ²²Ne¹⁰⁺ ion beam at 70 MeV/u have been studied by a newly installed resonant Schottky pick-up at the experimental cooler storage ring (CSRe), at IMP. For an RF-bunched ion beam, a longitudinal momentum spread of Δp/p=1.6×10^-5 has been reached with less than 10⁷ stored ions. The reduction of momentum spread compared with a coasting ion beam was observed from Schottky noise signal of the bunched ion beam. In order to prepare the future laser cooling experiment at the CSRe, the RF-bunching power was modulated at 25^th, 50^th and 75^th harmonic of the revolution frequency, effective bunching amplitudes were extracted from the Schottky spectrum analysis. Applications of Schottky noise for measuring beam lifetime with ultra-low intensity of ion beams are presented, and it is relevant to upcoming experiments on laser cooling of relativistic heavy ion beams and nuclear physics at the CSRe.     

Flat-band voltage shift in metal-gate/high-k/Si stacks

In metal-gate/high-k stacks adopted by the 45 nm technology node, the flat-band voltage (V_fb) shift remains one of the most critical challenges, particularly the flat-band voltage roll-off (V_fb roll-off) phenomenon in p-channel metal-oxide-semiconductor (pMOS) devices with an ultrathin oxide layer. In this paper, recent progress on the investigation of the V_fb shift and the origin of the V_fb roll-off in the metal-gate/high-k pMOS stacks are reviewed. Methods that can alleviate the V_fb shift phenomenon are summarized and the future research trend is described.     

含电学边界的压电层合梁的非线性弯曲波

非线性科学己成为近代科学发展的一个重要标志, 特别是非线性动力学和非线性波的研究对于解决自然科学各领域中遇到的复杂现象和问题有着极其重要的意义. 本文研究了含电学边界条件的压电层合梁的非线性弯曲波传播特性.首先, 考虑几何非线性效应和压电耦合效应, 利用哈密顿原理建立了一维无限长矩形压电层合梁弯曲波的非线性方程.其次, 采用Jacobi椭圆函数展开法对非线性弯曲波方程进行求解, 得到了非线性弯曲波动方程在近似情况下对应的冲击波解和孤波解.最后, 利用约化摄动法得到了非线性薛定谔方程, 进一步得到了亮孤子和暗孤子解.基于两种方法具体研究了外加电压、压电层厚度等参数对冲击波和孤立波以及亮孤子和暗孤子特性的影响. 研究结果表明, 在波速较小时, 外加电压对冲击波的影响较大, 波速较大时, 外加电压对孤立波影响减弱.通过调整作用在压电层合梁上的电压发现了存在亮孤子和暗孤子, 分析结果表明随着外加电压值的增大, 亮孤子和暗孤子的振幅都增大.      

近红外光谱定量分析土壤全氮含量预处理方法探讨

提高土壤全氮含量检测的精确性对于精准农业具有非常重要的意义。本文基于近红外光谱技术,对光谱数据预处理方法进行研究。以土壤全氮含量为检测对象,采用平滑+一阶导数、基线校正+归一化、一阶导数+归一化等方法对采集样品的光谱数据进行预处理方法干预,并运用PLS算法分别建立土壤全氮含量的预测模型,分析不同种预处理方法对于近红外光谱建模精度的影响。实验结果表明应用基线校正+归一化处理后建模得到的预测均方根误差RMSEP为0.025,决定系数R~2为0.98,预测精度最佳。