温度对光纤准直器的角度偏移影响分析

通过对光纤准直器准直失配，即离轴耦合、偏角耦合、间距耦合三种情况的耦合损耗进行分析，发现角度偏移对耦合效率影响最大.实验中随着温度周期性的变化，光斑位置也出现了有一定规律性的变化.实验通过确定光斑位置的变化量从而求出鞍型和拱型支承架在温度循环时的角度偏移为519 μrad和395 μrad，并导致了0.944 dB和0.718 dB的耦合损耗；在温度冲击时的角度偏移为986 μrad和138 μrad，并导致了1.793 dB和0.251 dB的耦合损耗.实验结果表明拱型支承架在两种不同的温度变化情况下均优于鞍型支承架.     

上海光源储存环恒流注入束流安全性模拟

针对恒流注入过程中在同步辐射光闸开启情况下的辐射安全问题，对注入电子束轨迹进行了模拟跟踪计算，考察电子束在什么样的极端情况下会从光束线通道打出造成辐射安全事故。束流动力学模拟采用Accelerator Toolbox (AT)程序，正向跟踪电子轨迹。在不丢失任何可能性的前提下，放大入射电子束相空间，减小跟踪距离，简化计算。通过模拟结果得到机器安全联锁保护条件，为保障安全的恒流注入提供依据。     

高准确度光束偏转装置的设计与分析

基于矢量折射定理推导了光束经过正交双棱镜后的偏转表达式.给出了装置的主要设计参量；用数值模拟的方法分析了主要误差项，求出了总误差和实际准确度指标.结果表明，光束在水平张角及垂直张角500 μrad内可实现准确度优于0.8 μrad的偏转，偏离准确度主要受随机误差影响；反映到棱镜转角上的总误差为12.72 arcsec,引起的光束偏离误差为0.365 μrad，大于系统读数分辨率0.0387 μrad,且小于光束偏离准确度指标0.8μrad.     

激光光束指向稳定性的测量

光束指向的精确测定技术是光路自准直系统的重要基础技术.本文给出了激光光束指向稳定性的测量方法,利用图像采集卡、CCD相机和自主研发的图像处理软件,对静态光斑及连续He-Ne激光器的输出激光束指向偏差进行实验检测.结果表明:给出的测量系统光束指向角度的测量精度接近1μrad.     

分离电离室同步辐射束线位置监测器

本文介绍的分离电离室同步辐射光束线(在X射线能区)垂直位置监测器,可同时监测束线绝对垂直位置和相对总强度.束线无阻挡通过.常规X源实验结果表明原理可靠,方法简便,性能稳定,可投入实用.     

高功率激光光束的自准直算法

为满足高功率激光装置全程光路自动准直快速性及高精度的要求,提出了一种光斑对应椭圆的长短轴差值法对光斑形状调节,并结合重心法快速、高精度的获取光斑图像中心位置.利用大律法、3×3邻域法及8向链码法对光斑图像进行处理,得到面积最大的光斑;分析最大光斑区域中心距,求出最大光斑对应椭圆的长短轴长,并根据长短轴差值调节光斑形状,至长短轴差值近似为零,获得形状最规则的光斑;分析形状最规则光斑的中心位置与其基准位置在x和y方向的偏差,并将该差值转为闭环控制的步进电机所需要调整的步数,实现激光光束的自准直.该算法应用在高功率激光装置中,结果表明,主放大光路的准直时间缩短为15min,近场准直的准确度优于0.2%,远场指向准确度优于1μrad,满足高功率激光光束的准直要求.     

高能光源增强器束流横向尺寸测量系统设计

高能同步辐射光源的增强器将直线加速器注入的束流加速到储存环所需的能量,为储存环提供高品质的电子束。为了对增强器的束流横向截面尺寸、发射度及能散进行测量,设计了两条可见光-紫外波段的束测光束线。两条光束线分别选取无色散和色散较大的两处弯铁位置作为光源点,使用两套同步光成像系统来监测光源点的束流截面尺寸,并计算束流发射度及能散。介绍了同步光引出真空室及光学成像系统,对影响成像质量的空间分辨率进行了分析,并针对升能过程中不同能量下束流光斑变化的测量进行了设计。     

激光光束实时监测与自动准直系统设计

设计了一个激光光斑实时监测与光路自动准直装置,能够实时监测激光光斑并自动准商激光输出方向.基于透镜成像原理,使用CCD探测器获得光斑的二维成像,并根据两点确定一条直线原理和使用压电陶瓷电动调整架实现光路自动准直;监测控制程序采用虚拟仪器开发软件Lab View编写,可以实时监测激光光斑模式与光斑位置抖动情况,并进行反馈控制.经测试,设计装置的调整精度达0.5μrad,反馈控制频率约1 Hz,完全可降低或消除抖动周期在1 s以上的光斑飘移.     

基于相控阵雷达模型的液晶光束偏转波控方法研究

针对闪耀光栅模型光束偏转角度数量分布有限的缺点，提出一种基于相控阵雷达模型的液晶光束偏转波控方法。该方法控制液晶电极间相位差，通过改变液晶电极间相位差控制出射光波束方向。使用傅里叶光学方法推导该模型最大偏转角度、光束偏转角度与电极间调制相位关系以及衍射效率和偏转角度的关系。实验证明该方法可实现任意分辨角的光波束扫描, 在0.15°光束扫描范围内实现优于20 μrad的连续光束偏转。     

高斯光束斜入射法布里—珀罗干涉仪的透射光强分布

基于多光束干涉原理,研究了高斯光束斜入射法布里—珀罗干涉仪的透射光强分布。结果表明,当以较大角度入射时,输出为一系列空间分离的光斑;当以较小角度入射时,输出尽管为单一光斑,但是与输入相比,其峰值强度位置发生了偏移,且光斑变大。     

合肥光源基于同步光的测量与研究

介绍了合肥光源同步光测量系统, 包括条纹相机系统、快速光电测量束团长度系统、束团横向截面测量系统和光位置测量系统. 利用条纹相机系统和快速光电测量束团长度系统进行了束团长度测量和束团伸长效应的研究. 利用束流截面测量系统进行了六极铁对横向不稳定性抑制效果和横向反馈系统反馈效果的测量研究. 光位置测量系统采用丝型光位置检测器和自行研制了对数处理器, 用于测量光源点的束流位置和角度.     

Diamond X‐ray beam‐position monitoring using signal readout at the synchrotron radiofrequency

Single‐crystal diamond is a material with great potential for the fabrication of X‐ray photon beam‐position monitors with submicrometre spatial resolution. Low X‐ray absorption combined with radiation hardness and excellent thermal‐mechanical properties make possible beam‐transmissive diamond devices for monitoring synchrotron and free‐electron laser X‐ray beams. Tests were made using a white bending‐magnet synchrotron X‐ray beam at DESY to investigate the performance of a position‐sensitive diamond device using radiofrequency readout electronics. The device uniformity and position response were measured in a 25 µm collimated X‐ray beam with an I‐Tech Libera `Brilliance' system. This readout system was designed for position measurement and feedback control of the electron beam in the synchrotron storage ring, but, as shown here, it can also be used for accurate position readout of a quadrant‐electrode single‐crystal diamond sensor. The centre‐of‐gravity position of the F4 X‐ray beam at the DORIS III synchrotron was measured with the diamond signal output digitally sampled at a rate of 130 Msample s^?1 by the Brilliance system. Narrow‐band filtering and digital averaging of the position signals resulted in a measured position noise below 50 nm (r.m.s.) for a 10 Hz bandwidth.     

第三代同步辐射光源X射线相干性测量研究

随着高性能第三代同步辐射光源的建成开放,基于X射线相干特性的实验方法得到了快速发展和广泛应用.作为一个典型的例子,X射线相位衬度成像已经成为常规的X射线实验方法并向用户开放.相干散射、相干衍射成像、光子关联谱等X射线实验方法正日益受到重视,在高空间分辨、时间分辨等研究领域已显示出其独特的优越性.因此,研究和测量第三代同步辐射的空间相干特性对进一步发展这些新的实验方法具有重要意义.基于Talbot自成像原理成功测量了上海光源X射线成像线站发射的X射线的空间相干长度,并进而测得了相应光源的空间尺度.光子能量为33.2 keV时,测得的X射线光束垂直方向空间相干长度为8.84μm,对应的光源尺寸为23μm,测量结果与理论分析相符.     

采用对数比处理技术的同步光位置测量系统

 对于双丝型同步光位置检测器，对数比处理技术较差比和处理技术具有更宽的线性范围和动态范围。利用美国BB公司的高精度对数运算放大器LOG112实现电流电压转换，研制了一种采用对数比处理技术的同步光位置测量系统，垂直方向光位置测量分辨率约为1 μm，线性范围大于±3 mm。与合肥同步辐射光源原有同步光位置测量系统相比，具有较高的性价比。     

一种带有弹簧的丝型同步光位置检测器

 介绍了合肥光源机器诊断光束线上具有弹簧系统的丝型光位置检测器，经过标定该检测器的线性范围大于4 mm，灵敏度约为0.197 9 mm^-1。通过不同束流流强下同步光垂直尺寸的测量，发现束流流强对同步光垂直尺寸的影响不大，不需要对灵敏度进行修正。进行了无氧铜板施加正偏压的测量，在施加正偏压时能够提高线性范围和略改善信噪比。     

Mössbauer optics of synchrotron radiation at an isotopic boundary

The inelastic coherent Mössbauer scattering (ICMS) of synchrotron radiation at an isotopic boundary—a flat interface between two regions of matter which have different concentrations of the Mö ssbauer isotope—is investigated theoretically. Attention is focused primarily on the ICMS component for which the absorption of a synchrotron radiation photon by a nucleus occurs with recoil, i.e., with the creation or annihilation of lattice phonons, and the subsequent process of reemission of a photon by the Mössbauer nucleus occurs without recoil, as a result of which radiation is pumped from the wide synchrotron radiation line into the narrow Mö ssbauer line. Formulas similar to the Fresnel formulas, well known in optics, for the transmission and reflection of light at a dielectric boundary are obtained for ICMS at an isotopic boundary. Specifically, it is shown that the angle of reflection for ICMS at an isotopic boundary is different from the angle of mirror reflection of a synchrotron radiation beam, and the direction of the ICMS transmitted through the isotopic boundary depends on the deviation of its frequency from the exact value of the Mössbauer resonance frequency and in general is different from the direction of propagation of the synchrotron radiation beam. The suppression of ICMS at grazing angles of incidence of the synchrotron radiation beam is analyzed. A similar problem is solved for a plate-shaped sample containing a Mössbauer isotope. It is shown that the specific nature of the ICMS at an isotopic boundary could be helpful in the problem of Mö ssbauer filtering of synchrotron radiation.     

Enhancing the accelerated beam current in the booster synchrotron by optimizing the transport line beam propagation

In this paper, we present the results of transverse beam emittance and twiss parameter measurement of an electron beam, delivered by a 20 MeV microtron which is used as a pre-injector system for a booster synchrotron in the Indus Accelerator Facility at RRCAT Indore. Based on these measured beam parameters, beam optics of a transport line was optimized and its results are also discussed in this paper. This beam transport line is used to transport the electron beam from the 20 MeV microtron to the booster synchrotron. The booster synchrotron works as a main injector for Indus-1 and Indus-2 synchrotron radiation facilities. To optimize the beam optics of a transport line for proper beam transmission through the line as well as to match the beam twiss parameters at the beam injection point of another accelerator, it is necessary to know the transverse beam emittance and twiss parameters of the beam coming from the first one. A MATLAB-based GUI program has been developed to calculate the beam emittance and twiss parameters, using quadrupole scan method. The measured parameters have been used for beam transport line optimization and twiss parameters matching at booster injection point. After this optimization, an enhancement of ～50% beam current has been observed in the booster synchrotron.     

光电效应光位置检测器的性能分析

介绍了几种同步辐射光源常用的光电效应光位置检测器 ,对其主要性能 (如灵敏度、零位偏差和线性范围 )进行了理论分析和比较 ,给出了计算机模拟结果 ,分析了加工误差对检测器性能的影响 ,为光位置检测器的设计提供了理论依据 ,并提出了一种改良型的光电效应光位置检测器。     

X‐ray beam‐position feedback system with easy‐to‐use beam‐position monitor

X‐ray beam‐position stability is indispensable in cutting‐edge experiments using synchrotron radiation. Here, for the first time, a beam‐position feedback system is presented that utilizes an easy‐to‐use X‐ray beam‐position monitor incorporating a diamond‐fluorescence screen. The acceptable range of the monitor is above 500 µm and the feedback system maintains the beam position within 3 µm. In addition to being inexpensive, the system has two key advantages: it works without a scale factor for position calibration, and it has no dependence on X‐ray energy, X‐ray intensity, beam size or beam shape.     

Angular dispersive diffraction using a diamond-anvil pressure cell and synchrotron X-ray source

Abstract

Wavelength dispersive diffraction studies have been performed using a diamond-anvil pressure cell and bending magnet synchrotron produced radiation. A double-crystal monochromator was used to select 15 and 17 keV photons and a 80 μm diameter collimator was used to restrict the beam entering the pressure cavity. Parallelism between the incident beam and the collimator axis was assisted by computer control of the collimator. The image of the transmitted beam was observed using a Hamamatsu x-ray Vidicon and TV monitor, for this alignment. The diffracted beam was recorded on x-ray film using a double film cassette and exposure times ranged from 6 to 8 hours. Neither the exposure time nor the line width of the diffraction lines was significantly altered by replacement of the incident beam collimator with a slit system.