等离子体钢丝二次谐波辐射的线性转换理论

本文对激光等离子体细丝的线性转换理论作了研究.通过对激光等离子体二次谐波的能量通量的计算发现,二次谐波的平面波理论关于在垂直密度梯度方向没有二次谐波辐射的结论与实验结果不符.在此基础上,我们提出了等离子体细丝的二次谱波线性转换理论,在垂直密度梯度方向有较强的二次谐波发射,这与实验结果较为一致.     

一种新型的多功能细丝直径测量仪

本文介绍了一种新型的细丝直径测量仪,文章详细地介绍了该仪器的测量系统,该仪器不仅能进行静态测量,还可进行在线动态测量,并能测量细丝的不圆度。测量范围为20～200微米,测量速度200次/秒,测量精度±0.5微米。本文还对它的功能和性能与国内外同类产品进行了比较,该仪器总体上是先进的。     

The propagation dynamics of ultraviolet light filament with Rayleigh scattering in air

In this paper we present for the first time the effects of Rayleigh scattering on the long distance propagation of ultraviolet （UV） light filament in air based on the stationary analysis. The simulation results show that the effects of Rayleigh scattering on the propagation of UV laser filaments may not be ignored. These influences are slightly dependent on the laser wavelength. We also compare the UV filament propagations at different input powers in the presence and the absence of the Rayleigh scattering and discuss the mechanisms of power loss and beam defocusing. In the absence of Rayleigh scattering, the filament propagation is determined by the oscillating behaviour of the beam size. In the presence of the scattering, the propagation lengths of filament are close to each other at different initial powers and determined by the Rayleigh scattering.     

逸出功测定实验研究

文章讨论了在逸出电位测定过程中两种灯丝电流和加速电压的调节方法。认为如果先固定加速电压当灯丝电流增大后,会导致加速电压的减小,使测量逸出电位的不确定度增大。所以在这种调节方法中,应该增大加速电压值,这样测量精度更高。     

高场强下半导体沿面闪络现象的研究进展

 综述了国内外半导体沿面闪络的研究现状，阐述了电极结构的类型和影响闪络的主要因素；根据自定义的等值电导参数将闪络的发展划分为欧姆电导、局部闪络和贯通闪络3个阶段；通过对表面细丝电流的热过程进行实验和仿真研究，认为表面细丝电流通道的温度可以接近材料熔点，这一结果同时也支持了表面发热导致气体分子解吸附的假设；进一步通过气体解吸附的实验初步确定了存在外部的闪络通道。     

用激光单缝衍射实验仪做扩展实验

在大学物理实验中,单缝衍射实验仪一般用来测量衍射光强分布和缝宽,本文对实验内容进行了扩展,增加了测量细丝直径、He-Ne激光束的光强分布、激光束光斑尺寸及发散角等内容.     

有关白炽灯的几个重要参数的测量

在已有的实验结果的基础上，通过建立物理模型，应用近似处理等方法简洁地测出了白炽灯正常发光时的灯丝温度值、可见光所占总能的比例、光通量等重要参数．     

Polypropylene Copolymers Designed for Fused Filament Fabrication 3D‐Printing

Several chemical properties which influence the printability for fused filament fabrication 3D‐printing are derived from analyses of commercially available filaments. In preliminary experiments, polymerization conditions are optimized and suitable monomers and selectivity control agents (donors) are selected. An experimental series in which propene is copolymerized with the comonomers 1‐butene and 1‐hexene with an industrial Ziegler–Natta catalyst will be discussed here. The experiments are planned using design of experiments. Based on a split‐plot design, the design is adapted for mixtures and the combination of homo‐ and copolymerization. The observed factors, besides the mixture composition, are hydrogen partial pressure and the amount of donor. The obtained polymers are analyzed by means of high‐temperature size exclusion chromatography, differential scanning calorimetry, and rheology. 1‐Butene copolymers show good printing results and promising properties almost matching the desired ones. The targeted polymer properties are achieved within certain limits. 1‐Hexene copolymers result in lower molecular masses while crystallinity remains slightly higher, which does not match with the desired profile. Beneficial properties are likely to be achieved within a wider factor range, for example, higher comonomer amount and lower hydrogen partial pressure.     

A Lie algebra structure on variation vector fields along curves in 2-dimensional space forms

A Lie algebra structure on variation vector fields along an immersed curve in a 2-dimensional real space form is investigated. This Lie algebra particularized to plane curves is the cornerstone in order to define a Hamiltonian structure for plane curve motions. The Hamiltonian form and the integrability of the planar filament equation are finally discussed from this point of view.