Study of Current Sheath Velocity and Its Distribution Using Tridimensional Magnetic Probe in Sahand Plasma Focus

The current sheath velocity in 0.25 Torr gas pressure of Filippov type plasma focus is studied experimentally. By using two tridimensional magnetic probes on top of the anode surface, the current sheath velocity is measured for argon, oxygen and nitrogen. Additionally, the effect of charging voltage on the current sheath velocity is studied in both axial and radial phases. We found that, the maximum current sheath velocities at both radial and axial phases are respectively 4.33 ± 0.28 （cm/μs） and 3.92 ± 0.75 （cm/μs） with argon as the working gas at 17 kV. Also, the minimum values of current sheath velocity are 1.48 ± 0.15 （cm/μs） at the radial phase and 1.14 ± 0.09 （cm/μs） at the axial phase with oxygen at 12 kV. The current sheath velocity at the radial phase is higher than that at the axial phase for all gases and voltages. In this study, variation of the full width half maximum （FWHM） of magnetic probe signals with voltage is investigated for different gases at radial and axial phases.

不同类型涡流探头对蒸汽发生器传热管缺陷检测能力的对比分析

为研究不同类型涡流探头对蒸汽发生器传热管缺陷的检测能力,分别采用轴绕式探头、旋转探头与阵列探头,对位于自由段的孔形、槽形、磨损缺陷和疲劳裂纹进行试验、对胀管过渡区孔形和槽形缺陷进行试验,还进行了缺陷分辨力试验,发现旋转探头与阵列探头具有相近的缺陷检出能力,对于间距较小的缺陷和胀管过渡段上的缺陷等复合缺陷,旋转探头与阵列探头的缺陷检出能力均明显优于轴绕式探头的。

The Effect of Ion Current Density on Target Etching in Radio Frequency-Magnetron Sputtering Process

The effect of ion current density of argon plasma on target sputtering in magnetron sputtering process was investigated. Using home-made ion probe with computer-based data acquisition system, the ion current density as functions of discharge power, gas pressure and positions was measured. A double-hump shape was found in ion current density curve after the analysis of the effects of power and pressure. The data demonstrate that ion current density increases with the increase in gas pressure in spite of slightly at the double-hump site, sharply at wave-trough and side positions. Simultaneously, the ion current density increases upon increase in power. Es- pecially, the ion current density steeply increases at the double-hump site. The highest energy of the secondary electrons arising from Larmor precession was found at the double-hump position, which results in high ion density. The target was etched seriously at the double-hump position due to the high ion density there. The data indicates that the increase in power can lead to a high sputtering speed rate.

碳钢件焊缝缺陷检测用正交涡流探头研究

由于传统涡流探头具有明显的提离效应,难以检测表面不平整的焊缝。为此,基于均匀涡流检测原理,设计一种用于焊缝缺陷检测的正交涡流探头。采用理论计算方法,研究正交探头检测原理,设计探头有限元仿真模型,分析探头结构和线圈尺寸对检测灵敏度的影响。利用设计的正交涡流探头对碳钢件焊缝开展探伤检测试验。当提离量不大于2 mm时,有效检测出宽度为0.25 mm、深度为1 mm的碳钢板焊缝表面人工开口裂纹。试验结果表明,正交涡流探头能有效抑制检测过程中提离效应的影响,验证了探头用于焊缝表面缺陷检测的可行性。

直流电弧等离子体炬数值模拟与诊断

直流电弧等离子体炬内部物理过程复杂且具动态性,较难对其进行准确描述与深入研究,且其工作温度较高,其状态参数难以使用常规方式测量。针对直流电弧等离子体炬,建立流动、传热和电磁相互耦合的数值模型,基于Fluent软件对直流电弧等离子体炬进行三维数值模拟和特性分析,设计并搭建了一套热焓探针实验系统,完成对直流电弧等离子体炬射流参数的测量分析。结果表明:建立的数值模型模拟结果与实验测量结果吻合较好,误差在10%以内;炬内温度与速度最大值与工作气流量呈正相关,均出现在靠近阴极区域,且沿轴线逐渐降低;等离子体炬内高温区与高电流密度区重合。

涡流X-probe探头的试验及应用

探头是阵列涡流检测的关键部件,介绍了一种新型的内穿过式涡流阵列探头——X-probe。分析了X-probe探头的工作原理,并通过试验研究,归纳了X-probe探头检测的不同类型缺陷信号特征、支撑下缺陷响应以及伤深与相位的关系。并介绍了X-probe探头在核电厂凝汽器传热管涡流检查的应用情况。试验结果表明,X-probe探头能够获取缺陷轮廓并依据AF和CF通道的幅值分辨出缺陷方向。现场应用证实X-probe探头具有良好的管板区缺陷检出能力,能很好地检测分辨并测量周向复合缺陷的伤深。

基于刀片式激励线圈旋转的脉冲涡流探头

脉冲涡流检测裂纹时,微裂纹在感应涡流中产生的扰动微弱,检测信号的信噪比低;另一方面,单向扫查下的常规脉冲涡流探头难以获得多向裂纹检测的最大灵敏度和判断裂纹方向。提出一种采用机电旋转脉冲涡流激励线圈的检测方法,实现了多方向微裂纹的高灵敏度检测。刀片式激励线圈具有明显的聚磁性与方向性,机电旋转激励线圈后可以获得不同转角下的接收信号,将该接收信号与基准信号进行差分,提取出微小的峰值变化量,得到角度与峰值变化量之间的图谱。试验验证与测试结果表明:基于刀片式激励线圈在空心接收线圈内旋转的脉冲涡流探头不仅具有亚毫米级裂纹深度区分的检测能力,且能有效分辨裂纹方向,误差为±5°。

ARRAY PULSED EDDY CURRENT IMAGING SYSTEM USED TO DETECT CORROSION

A theory model is established to describe the voltage-current responsefunction. The peak amplitude and the zero-crossing time of the transient signal is extracted as theimaging features, array pulsed eddy current (PEC) imaging is proposed to detect corrosion. The testresults show that this system has the advantage of fast scanning speed, different imaging mode andquantitative detection, it has a broad application in the aviation nondestructive testing.

Automatic emissive probe apparatus for accurate plasma and vacuum space potential measurements

We have developed an automatic emissive probe apparatus based on the improved inflection point method of the emissive probe for accurate measurements of both plasma potential and vacuum space potential.The apparatus consists of a computer controlled data acquisition card,a working circuit composed by a biasing unit and a heating unit,as well as an emissive probe.With the set parameters of the probe scanning bias,the probe heating current and the fitting range,the apparatus can automatically execute the improved inflection point method and give the measured result.The validity of the automatic emissive probe apparatus is demonstrated in a test measurement of vacuum potential distribution between two parallel plates,showing an excellent accuracy of 0.1 V.Plasma potential was also measured,exhibiting high efficiency and convenient use of the apparatus for space potential measurements.

The Langmuir Probe onboard CSES: data inversion analysis method and first results

The Langmuir Probe(LAP), onboard the China Seismo-Electromagnetic Satellite(CSES), has been designed for in situ measurements of bulk parameters of the ionosphere plasma, the first Chinese application of in-situ measurement technology in the field of space exploration. The two main parameters measured by LAP are electron density and temperature. In this paper, a brief description of the LAP and its work mode are provided. Based on characteristics of the LAP, and assuming an ideal plasma environment, we introduce in detail a method used to invert the I-V curve; the data products that can be accessed by users are shown. Based on the LAP data available, this paper reports that events such as earthquakes and magnetic storms are preceded and followed by obvious abnormal changes. We suggest that LAP could provide a valuable data set for studies of space weather, seismic events, and the ionospheric environment.

Symmetric Temperature Compensation for Photoelectric Coupling Current Transducer

The temperature characteristic of sensor probe at high voltage side is analyzed by using a photoelectric coupling current transducer. The principle of symmetric temperature compensation and the main idea of software design are proposed. The method increases measuring precision and has fairly great practicability.

A NEW INTELLIGENT AMPEROMETRIC TYPE OF ELECTROCHEMICAL HYDROGEN PROBE

A new intelligent amperometric type of electrochemical hydrogen probe to measure hydrogen atom permeation rate in the metals was devised and developed. Combined with MCS51 single slice computer system, specially programmed software was designed for data sampling, logging, storing, processing, result judgment and data output controlling. The probe is portable and can be used in both lab and in site automatically.

kA级脉冲电流注入环的SPICE电路模型

在考核电力/电子设备抗强电磁脉冲性能的千安培(kA)级脉冲电流注入试验中,注入环通过感性耦合的方式将脉冲源输出能量加载到受试设备端口,是注入试验平台的重要组成部分.为解决kA级电流注入环的时域电路仿真难题,本文以Montena IC3B型注入环为例,采用多段集总参数电路串联的方法,建立了考虑分布参数因素的kA级注入环SPICE(Simulation Program with Integrated Circuit Emphasis,SPICE)电路模型;并依据注入环磁芯材料特性,对端口阻抗测试数据进行了分频段拟合,采用粒子群优化算法求取了电路模型参数;最后将该模型应用于kA级脉冲电流注入平台的整体电路仿真,并进行了实验验证,结果表明该模型具有较高的时域仿真精度,可用于电力/电子设备强电磁脉冲电流注入试验的设计、分析、效果预估等工作.

航空发动机关键部位热障涂层厚度智能反演算法

热障涂层(thermal barrier coating,TBC)是一种由金属粘接层和陶瓷层构成的隔热材料,具有热导率低、抗热疲劳及耐高温氧化等优异性能,能够很好地在高温环境下保护发动机关键部位。针对某关键部位多曲面基体热障涂层厚度的涡流检测,设计R45.5 mm以及R72.5 mm两种弹压式涡流传感器,建立3种机器学习算法的反演模型,并对曲面模拟试样进行测量,最后验证3种算法的反演精度。结果表明:R45.5 mm曲面试样随机森林算法的粘接层最大相对误差为9.01%,陶瓷层最大相对误差为4.33%;R72.5 mm曲面试样随机森林算法的粘接层最大相对误差为5.23%,陶瓷层最大相对误差为6.28%,均小于工业误差要求10%。

油气管道裂纹涡流检测探头的研制

分析了基于涡流传感技术的油气管道裂纹检测机理,开发了一种裂纹检测系统,研制不同结构参数的检测探头,对含裂纹试件进行扫查。试验结果表明,环形激励线圈的高度和匝数对探头的检测能力影响显著,减小线圈高度、增加匝数有利于提高探头的裂纹检测性能;研制的涡流检测探头可实现宽1mm裂纹的有效检出。

一维法拉第探针阵列束流发散角测量试验研究

研制了用于空间电推进束流发散角测量的一维法拉第探针阵列(FPA),在LIPS-200离子推力器上进行了固定截面和多截面的束流发散角测量试验。试验结果表明:固定截面下一维FPA测量的束流发散角为26.74°±0.04°(置信度P=95.45%),该测量结果与米字型FPA测量的结果(27.07°±0.18°,P=95.45%)的相对误差为1.2%,其合成标准不确定度仅为米字型FPA测量合成不确定度的22.2%。多截面下一维FPA测量的束流发散角为26.54°±0.56°(P=95.45%),该测量结果与固定截面下的测量结果的相对误差只有0.8%,表明多截面下一维FPA测量束流发散角技术是可信的。与传统的米字型FPA相比,一维FPA具有体积小、质量轻、空间分辨率高和动态扫描范围大等特点,同时还可以与推力测量设备集成,降低试验成本。

基于双切向涡流的阵列探头设计及仿真

承压类特种设备在石油化工等行业应用广泛,然而,出于防腐等需要,承压设备外常涂有涂层,给检测带来了难度。针对涡流检测技术在带涂层检测中的应用,提出了一种基于双切向涡流的阵列探头,并对其阵列单元的性能和阵列探头的整体结构进行分析和设计。理论分析表明,所提出的阵列单元可消除激励线圈到接收线圈直接耦合信号的影响,同时,该探头能够同时实现对不同长度和不同角度裂纹的定量分析,进而提高裂纹的检测精度。此外,为减小提离效应对检测结果的影响,设计了带有弹簧的阵列探头结构,弹簧始终处于压缩状态,以保证在检测过程中探头的提离最小,该研究可为带涂层设备的检测提供一定技术支持。

动车组牵引系统传导干扰电流监测探头的设计

动车组牵引系统绝缘栅双极型晶体管开关模块的快速通断会在变流器输入输出侧产生差模传导电流,该电流会导致牵引变流系统传导干扰的产生,因此差模传导电流可以用于牵引变流器工作状态的监测。针对满足差模传导电流探头的带宽、灵敏度和尺寸的设计需要准确地求解电流探头的关键寄生参数的问题,提出了一种求解集总参数的方法。通过理论分析和三维软件仿真,对磁芯、绕线和尺寸进行合理选择,最后设计出一个小尺寸、高阻抗的高频电流探头以及相匹配的校准夹具。校验试验结果表明,电流探头满足设计需求,可以动车牵引系统传导干扰电流监测提供技术支持。

基于ZYNQ的阵列涡流无损检测系统

圆柱形金属试件的阵列涡流检测可以通过几个围绕试件布局的阵列线圈组成的探头来完成,阵列涡流探头由完全相同的8个线圈组成并在一定的空间结构下完成对金属试件的探测。设计1个基于Zynq-7020的阵列涡流检测系统,该系统借助激励通道的8个模拟开关可以对一个或多个线圈进行激励,借助一个8选1模拟开关可以对8个阵列线圈进行分时采集,通过数字相敏检波算法完成对信号的提取。试验结果表明,此系统可以保存、传输、处理阵列探头的激励信号和感应信号,并完成测量阵列探头灵敏度的试验任务。