Shape measurements of mirror surfaces with a lateral-shearing interferometer during machine running

A common path lateral-shearing interferometer with a minimum number of optical components has been developed. Because the interferometer is little affected by mechanical vibrations and air turbulence, it can be mounted on an ultraprecision lathe and can be used to measure the shapes of workpieces. A plane parallel glass plate is used to shear the wavefront under test in the interferometer. To analyze the interference fringes obtained by the interferometer precisely, a fringe-scanning method using a slight tilt of the glass plate is used. Zone plates that are computer-generated holograms are used to measure spherical and aspherical surfaces with the interferometer. A spherical and a parabolic concave mirror were measured with the interferometer. The spherical mirror was also measured by a Fizeau interferometer to compare the error with that measured by the lateral-shearing interferometer. The experimental results agreed well with those measured by the lateral-shearing interferometer.     

Real-time reflectometry measurement validation in H-mode regimes for plasma position control

It has been shown that in H-mode regimes, reflectometry electron density profiles and an estimate for the density at the separatrix can be jointly used to track the separatrix within the precision required for plasma position control on ITER. We present a method to automatically remove, from the position estimation procedure, measurements performed during collapse and recovery phases of edge localized modes (ELMs). Based on the rejection mechanism, the method also produces an estimate confidence value to be fed to the position feedback controller. Preliminary results show that the method improves the real-time experimental separatrix tracking capabilities and has the potential to eliminate the need for an external online source of ELM event signaling during control feedback operation.     

Characterization of micromachined mirror surfaces from high speed diamond fly cutting

The measurement of the surface finish of diamond “fly-cut” mirrors is discussed. By considering each surface as a series of superimposed sinusoidal gratings, the surface spectral density function (SDF) was calculated from measurements of light scattered from an He-Ne laser beam. The SDF allows examination of the roughness as a function of spatial frequency from which the r.m.s. roughness is calculated. The scattering results are compared with other methods of assessing the surface finish of the mirrors. Results from Talystep measurements compare favourably with those from the lightscattering technique for the smooth copper mirrors, the best of which had a total r.m.s. roughness of 33 Å. The apparatus developed is described. Problems encountered with stylus methods, interferometry and scanning electron microscopy are reported.     

High accuracy profile measurement of quasi-conical mirror surfaces by laser autocollimation

A method is described for measuring the profile of a quasi-conical mirror surface along one of its axial generators. A laser beam is made to scan the surface and the variation in reflected beam angle is measured by autocollimation. Integrating the angle with respect to distance along the generator gives the profile height to within ±5 nm. The method has application to the metrology of X-ray microscope reflecting objectives     

Pulse compression radar reflectometry to measure electron density in plasma with parasitic reflections

Pulse compression radar reflectometry is used to obtain electron density profile in plasma with parasitic reflections in this article. The pulse compression radar relies on the relation between the temporal width of a pulse and the frequency bandwidth of this pulse: Deltat proportional, variant1Deltaf. So a set of sweep-frequency microwaves within a bandwidth Deltaf can be introduced sequentially into the plasma to obtain the same information as the one obtained by a real pulse. By applying a Fourier transform to the data of reflectivity array in the frequency domain, the temporal response in the time domain is obtained. The limitation of the parasitic reflections on measurement can be eliminated from the temporal response by the method of time gate. This is a prominent advantage when this method is compared to the traditional reflectometry. For this method, an appropriate compromise between the spatial resolution and the electron density resolution is important. Experimental results show that the profile obtained from pulse compression radar reflectometry is similar to that from a double Langmuir probe.     

Spectroscopic and scanning probe studies of oxygen and water on metal carbide surfaces

Spectroscopic and scanning probe techniques were applied to the study of clean, (100) single-crystal surfaces of titanium carbide (TiC) and vanadium carbide (VC), and their interactions with oxygen and water. We find that oxygen adsorbs dissociatively on both surfaces, but discriminates between them by reacting with TiC to form an oxide while forming a metastable overlayer on VC. Water bonds molecularly and dissociatively at low temperatures and behaves similarly on both materials. These results are interpreted in the context of surface electronic structure. This revised version was published online in June 2006 with corrections to the Cover Date.     

等离子粉末喷焊技术在阀门密封面上的应用

介绍了等离子粉末喷焊技术的原理、特点以及在阀门密封面制造中应用的优越性及经济性效益分析。     

Analysis on formation mechanism of ultra-smooth surfaces in atmospheric pressure plasma polishing

Atmospheric pressure plasma polishing (APPP) is developed for the final finishing of high quality ultra-smooth surfaces. To improve surface quality, formation mechanism of ultra-smooth surfaces in APPP is studied. Quantum chemistry simulation is used to investigate the interaction between atoms. Simulation of single Si-F bonding process indicates 0.2 eV difference of binding energy between convex and concave models, which reflects the reaction probability of convex structure is higher than that of concave structure. By comparing the spatial atomic configuration and species diffusion path, it is also demonstrated convex topography should be removed faster than concave topography. So roughness of optical surfaces can be reduced further to form ultrasmooth surfaces. And experimental results accord well with theoretical analysis. Detected by atomic force microscopy every 40 s, the average maximum height of surface is testified to decrease faster than the maximum depth obviously, which makes the whole surface going toward a new equilibrium status with lower roughness. Another experiment proves the average surface roughness decreases from Ra 4.529 to 0.926 nm after 100 s continuous machining. And the stereo images also indicate obvious improvement of surface topography. Moreover, free outmost electron is proved to be helpful to promote chemical reaction by simulation, so fresh surfaces may be more favorable for APPP which makes sample preparation more purposeful.     

Experimental device for the observation of rubbing surfaces during braking tests

This paper introduces an experimental device, developed at the Laboratoire de Mécanique de Lille, specially designed for application in braking tests. The purpose of this device is to monitor the course of events on the rubbing surfaces during simulated braked stops and, in particular, the life and the dynamics of the third body. The usefulness of the device is demonstrated by the results of braking experiments performed on a grey cast iron disc for two different energies. These first experimental results show that the technique provides efficient and exploitable observations of tribological phenomena occurring on the wear‐track scale as well as on the microscopic scale. Copyright © 2006 John Wile & Sons, Ltd.     

Wolter-I型掠入射反射镜的加工

针对Wolter-Ⅰ型掠入射反射镜柱面内表面的特殊结构,研究了弹性球状小磨头以旋偏方式运动逐环带修正面形时的去除函数模型.分析了相关工艺参数,如磨头-工件旋转角速度比、旋偏角大小、磨头中心压强以及磨头和工件的趋近距离对去除函数的影响,通过实验获得了驻留时间和去除函数中心去除深度的关系.采取两步加工法控制研抛后的表面质量,分析表明:当磨头-工件角速度比为1.41时,反射镜的表面质量最好.介绍了计算机控制光学表面成形(CCOS)法加工Wolter-Ⅰ型掠入射反射镜的过程.选择微晶玻璃为反射镜的镜胚,在自行研制的研抛设备上,以不同粒径的氧化铈作为抛光液,对金刚砂砂轮粗磨后的工件进行抛光.通过改变磨头相对工件的压人深度,获得不同大小的磨头去除区域,实现了对上一个抛光周期后的残留误差的有效去除.最终获得的反射镜面形精度为PV:1.39 μm,RMS:0.34 μm,圆度均方根误差优于0.1 μtm.实验结果表明:提出的两步法旋偏加工方案可用于掠人射反射镜的加工.     

Spectroscopic studies of the interaction of a high-power plasma stream with a solid on the GOL-3 facility

Experiments involving irradiation of carbon targets with a hot electron plasma stream performed on the GOL-3 facility were aimed at the simulation of the effect of hot plasma of a thermonuclear reactor on plasma collectors in regimes close to those expected in the ITER. In these experiments, the emphasis was on the study of the surface-erosion processes exposed to the plasma stream. The graphite evaporation and chemical-erosion processes were studied with absolutely calibrated spectroscopic systems of the visible region. Spectroscopic experiments yielded data on the flow of carbon atoms from the surface of a plasma collector and on the contribution of chemical erosion to the surface-damage process. The obtained values are compared with the results of direct measurements of the erosion depth and the results of numerical calculations.     

Study of the geometric characteristics of friction surfaces of diamonds during polishing

The surface of brilliant friction is studied during polishing on an industrial machine using the method of atomic-force microscopy. It has been established that the function of the distribution of profile coordinates is normal; the roughness of the friction surface is ~0.68–1.3 nm. To describe the formation of the profile for the brilliant friction surface statistically, as mathematical model based on the theory of random processes has been proposed.     

Mechanism of antiscuff action of thiols during boundary friction of steel surfaces

An analysis of antiscuff parameters of thiols, organic sulfides, and disulfides dissolved in Vaseline oil at the same sulfur concentration has been carried out. It was shown that thiols exceeded organic disulfides in critical load, while organic disulfides exceeded thiols in the welding load. Oxygen-containing iron dithiolates were superior to iron dithiolates in the critical load. A possible mechanism for the antiscuffing effect of thiols during the boundary friction of steel surfaces is proposed.     

Modifying the surfaces of fluorocarbon polymer implants in the plasma of a high-voltage nanosecond discharge

The possibility in principle is shown for rapidly and efficiently modifying the surface of medical articles made of polytetrafluoroethylene (PTFE) by placing them in a bulk plasma discharge formed in a highly overvoltage gap. As an example, by processing PTFE films with nanosecond discharges at a frequency of 3 kHz over a few seconds, it is possible to substantially improve the conditions for cytoadherence and increase the permeability of an implant, which is an important factor for its integration into adjacent tissues.     

新型薄膜反射镜的有限元分析

薄膜反射镜是实现大口径、低面密度空间光学系统的最新方向之一,材料采用柔性薄膜,具有重量超轻、体积小的特点.由于薄膜反射镜的挠度特性,利用传统的方法来获得面形的变化很困难.介绍薄膜反射镜的成形原理,建立符合实际情况的有限元模型,通过施加一定的边界条件,对薄膜反射镜进行非线性分析,得到一系列的挠度值,并和理论值进行比较分析,最大误差为0.07%.所得到的结论对于进一步研究反射镜成形和面形控制,以及薄膜厚度的选择具有一定的指导意义.＃     

主反射镜的一种轻量化设计和加工

报告了φ354mm轻质主反射镜的设计和制作工艺方法.用有限元法对镜面进行了力学分析,确定了加工和检测状态下的镜子装夹方案.检测镜面的结果表明这种方法是实用的.     

Estimation of the sensitivity of acoustic reflectometry to flaws in heat-exchange pipes

A novel approach to calculating the acoustic tract in the method of acoustic reflectometry is suggested for inspection of heat-exchange pipes. Results of modeling and analysis of the acoustic tract are presented. The sensitivity of acoustic reflectometry to flaws in the form of through holes and deposits against the background of acoustic noises due to permissible deviations in the thickness of the pipe wall is estimated.