螺旋型波荡器辐射特性及光束线前置镜热载分布

对合肥国家同步辐射实验室(NSRL)引进、装备的螺旋型电磁波荡器进行了改造和性能研究,该螺旋型电磁波荡器被插入电子储存环的直线段,来产生高通量圆偏振相干光,提供一条真空紫外光束线,用于燃烧科学研究.基于NSRL改造后的光源参数,分析其同步辐射偏振特性,计算了该波荡器辐射出的总功率和功率密度分布,以及受其直接辐照的光束线...     

上海光源真空紫外角分辨光电子能谱束线设计

在上海光源上设计了一条光子能量覆盖5~140 eV的高通量、高分辨的真空紫外角分辨光电子能谱束线。本光束线采用准周期椭圆偏振波荡器光源,其周期长度为0.32 m,周期数为14。单色仪采用Dragon型,分为覆盖5~32 eV的低能分支和25~140 eV的高能分支。计算表明,当入射/出射狭缝开启宽度为5/5 μm时,在整个能量扫描范围内,单色仪分辨率可以高达15 000~100 000,光学元件的面型误差对分辨率的影响最大。通量计算显示,样品处s偏振光子通量高达~10¹² phs/s。Shadow追迹模拟结果表明,设计的光束线具有很好的聚焦特性。     

上海光源新型一维位置灵敏电离室研制

研制了一台一维位置灵敏电离室。该电离室的收集电极由两块完全一样的相互独立并彼此绝缘的单元构成,每个单元有两路劈裂式极板,根据输出的电流信号可获得X光束的强度和位置。该电离室在上海光源(SSRF)生物大分子晶体学光束线上进行了实验测试,测试中采用了一个标准电离室作为强度测量对照。一维位置灵敏电离室被固定在一维电控滑台上,在水平方向上移动电控滑台逐步扫描测试光束的位置。测量时,光子能量为8keV,扫描范围为10mm,重复扫描12次;测试内容包括电离室的坪区、线性度、位置测量精度及光强。结果表明,该电离室的线性度较好,位置测量精度好于20μm,线性测量范围为6mm。它将安装在生物大分子晶体学光束线站上用于光束稳定性的监测。     

软X射线辐射测量

在软X射线辐射测量中,和光度学一样,光源标准和探测器标准都同时存在,长春光机所八十年代初,研制了真空紫外光谱区的标准光源;近两年研制了软X射线标准探测器稀有气体电离室和传递标准探测器Al₂O₃光二极管。电离室光谱响应的稳定性和重复性好于±2%;光谱辐射绝对定标的不确定度小于±5%。Al₂O₃光二极管光谱响应稳定性好于±2%,数只二极管的一致性好于±6%。     

梦之线光栅单色器温度起伏对能量漂移的影响

为了确保光栅单色器温度起伏引起的能量漂移不影响光束线的表观能量分辨率,建立了单色器高精度的恒温环境。结合上海光源梦之线设计,根据光栅衍射方程推导出单色器温差与能量漂移之间的关系;据此设计了沿光束方向温度起伏较小的单色器恒温环境,测试了温度控制系统不同条件下的长期温度稳定性,并通过长时间多次测量氮气K边吸收谱的方法,得到了相应的能量漂移。结果显示:温度控制系统未启动的情况下,棚屋内最大温度变化约为0.62K,测得的能量漂移约为49 meV;温度控制系统使用独立冷水机时,最大温度变化约为0.20 K,相应的能量漂移约为17meV。实验表明,建立的单色器恒温环境满足设计要求,使得单色器温差引起的能量漂移对梦之线表观能量分辨率的影响得到有效控制。     

一种新型四光束光纤浊度仪的研制

设计了一种新型四光束在线浊度仪.介绍了仪器的工作原理和探头的结构.采用光纤传输光信号,有效地避免了水样中气泡、背景颜色和杂散光的干扰.双光源双光电探测器的结构模式,消除了光电器件老化和水样中气泡对探测结果的影响,提高了测量精确度和稳定度,仪器可用于在线测量.     

荧光靶束流观测器设计的探讨

合肥国家同步辐射实验室800Mev同步辐射装置的主体设备是一台能量为800Mev、平均流强为300mA的储存环,用能量为200Mev的直线加速器作为注入器,电子束经直线加速器加速后通过输运线注入储存环。束流监测系统分别配置在直线加速器、输运系统和储存环,用于监测束流流强、束流位置、截面分布、量子寿命及振荡频率等性能参数。荧光靶束流观测器是一种结构、原理较为简单的束流截面监测装置,分别配置在直线加速器的“2759束测段”(即第一测量段)、“1225束测段”(即第三测量段)、输运线、注入口及储存环、用于直接观测束流的强弱及其截面分布。在加速器最初的调试运行期间颇为有用。图1为装在直线加速器上的荧光靶束流观测器。     

真空紫外双等离子管光源

双等离子管光源是一低气压、热阴极弧光放电真空紫外(20nm—100nm)光谱光源.光源具有良好的稳定性和重复性, 在光谱辐射计量及光谱学领域的研究中有广泛应用, 它不但具有Penning光源和毛细管放电光源的优点, 而且还补充了它们的不足.     

一种大功率激光输出功率低频波动的直接测量法

提出一种新的对大功率激光低频波动的测量技术.它的传感器是一根细小的探针,探针上面有一直径为20～500μm的微孔,光通过微孔对激光进行采样,由探针内通道将该采样光传输到探测器.探针可抗高功率激光损伤.由恒速电机带动探针高速扫描光束截面,最终获得激光输出功率随时间的变化信息.该仪器既可进行在位测量又可进行在线测量,既可测量CO2激光又可测量YAG激光.介绍了测量原理、仪器结构和实验结果.     

光电编码器LED光源的准直

由于发光二极管(LED)光束的准直度对光电编码器性能影响很大,研究了LED光束的准直特性.分析了光源辐射角对光栅光通量的影响;运用图像旋转理论和频域分析方法,导出了莫尔条纹透光特性函数式,揭示了光源准直度参数对莫尔条纹函数特性的影响.获得了与光束准直度相关的不同透光缝宽度下的莫尔条纹仿真波形,分析了光源准直特性指标对莫尔条纹对比度以及光栅间隙的影响.理论计算结果表明,当透光缝宽度减小5 μm时,莫尔条纹图像的对比度下降17.66%,实验结果与理论仿真波形吻合,表明文中提出的莫尔条纹函数式可为高精度和高可靠性编码器没计和生产提供参考.     

Recent progress in vacuum-ultraviolet polarization modulation spectroscopy using polarizing undulator at the TERAS BL5 beamline

Polarization modulation spectroscopy using an Onuki-type undulator is a useful technique for circular dichroism study in the vacuum-ultraviolet region. We have been developing the vacuum-ultraviolet circular dichroism (vuv-CD) spectroscopy in TERAS BL5 beamline at AIST. This paper describes recent improvements in our instrumentation and methods of analysis to achieve precise and absolute measurements. The CD signal is usually accompanied by experimental artifacts, and elimination of all possible artifacts is the key issue for making reliable measurements. After improving beamline optical system, light flux monitor, and undulator operation method, the base line shift of the CD spectrum is suppressed less than 3x10(-4). Sample manipulation and data processing procedures are also described and absolute CD spectrum can be obtained even for linear anisotropic sample. These progresses lead to more quantitative comparison of experimental with calculation on vuv-CD spectrum.     

Single-shot beam-position monitor for x-ray free electron laser

We have developed an x-ray beam-position monitor for detecting the radiation properties of an x-ray free electron laser (FEL). It is composed of four PIN photodiodes that detect backscattered x-rays from a semitransparent diamond film placed in the beam path. The signal intensities from the photodiodes are used to compute the beam intensity and position. A proof-of-principle experiment at a synchrotron light source revealed that the error in the beam position is reduced to below 7 μm by using a nanocrystal diamond film prepared by plasma-enhanced chemical vapor deposition. Owing to high dose tolerance and transparency of the diamond film, the monitor is suitable for routine diagnostics of extremely intense x-ray pulses from the FEL.     

EUV Optical Design-Reflective and Diffractive Optics

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A simple method for formation of the matching input in a helical undulator

A helical undulator is widely used in free-electron lasers with pulsed electron beams. An adiabatic input with a length of 5–10 periods is commonly used to inject the beam. A novel and simpler method for matching the undulator input is proposed, theoretically investigated, and experimentally implemented. The end field is formed with the help of wire sections in the form of straight lines and circular arcs, which permits an accurate control of geometrical dimensions. The axial length of this section is ∼1/6 of the undulator period. Experimental results obtained on the undulator with a period of 4.8 cm agree well with theoretical data.     

Laser ion source with solenoid for Brookhaven National Laboratory-electron beam ion source

The electron beam ion source (EBIS) preinjector at Brookhaven National Laboratory (BNL) is a new heavy ion-preinjector for relativistic heavy ion collider (RHIC) and NASA Space Radiation Laboratory (NSRL). Laser ion source (LIS) is a primary ion source provider for the BNL-EBIS. LIS with solenoid at the plasma drift section can realize the low peak current (～100 μA) with high charge (～10 nC) which is the BNL-EBIS requirement. The gap between two solenoids does not cause serious plasma current decay, which helps us to make up the BNL-EBIS beamline.     

High-performance soft x-ray spectromicroscopy beamline at SSRF

The Shanghai Synchrotron Radiation Facility (SSRF) is the first third-generation synchrotron facility in China and operated at an electron energy of 3.5 GeV. One of the seven beamlines in the first construction phase is devoted to soft x-ray spectromicroscopy and is equipped with an elliptically polarized undulator light source, a plane grating monochromator, and a scanning transmission x-ray microscope end station. Initial results reveal the high performance of this beamline, with an energy resolving power estimated to be over 10,000 at the argon L-edge and a spatial resolution better than 30 nm.     

大曲率弧矢弯曲复合晶体的研制

为提升国家同步辐射实验室X射线吸收精细结构(NSRL-XAFS)的光束线性能,提出将现有双平面晶单色器改造成弧矢聚焦双晶单色器的思想。采取将晶体与钛合金复合的工艺,实现了晶体的大曲率弹性弯曲,并将其用作弧矢聚焦晶体单色器中第二晶体的成像元件。鉴于NSRL-XAFS实验的光学要求,设计制作了复合晶体试验模型,通过有限元分析计算和长程面形仪实际测量得到了不同弯曲半径下晶体的面形精度,并用激光模拟其聚焦性能。结果表明,在缩放比为1/3时,样品上的成像束斑水平尺度(FWHM)由43mm(无聚焦)缩小到3mm,光子密度提高了近一个量级。这些结果满足NSRL在现有光源条件下提升XAFS数据采集质量的要求。     

用于星上定标光源的LED筛选装置

考虑将发光二极管(LED)用作空间相机星上定标光源时对LED的发光一致性和稳定性的要求,研究了对市售LED产品进行试验和筛选的方法。分析了影响LED发光效率的因素及LED作为星上定标光源需要注意的问题,提出了将多只LED作为空间相机星上定标光源的筛选试验方案,并设计、研制了筛选装置。为了检验LED的工作稳定性和不同LED的发光一致性,该装置可同时监测多只LED的发光状态,并实现了无人值守操控和自动测量。利用该装置对某批次72只随机抽取的白光LED进行测试并根据测试数据对被筛选的白光LED进行了分析计算,结果显示,经过筛选的白光LED在连续点亮900 h后,相对光强变化在1.5%左右。最后,从中筛选出符合光源要求的10只LED。     

Characterization of the Li beam probe with a beam profile monitor on JET

The lithium beam probe (LBP) is widely used for measurements of the electron density in the edge plasma of magnetically confined fusion experiments. The quality of LBP data strongly depends on the stability and profile shape of the beam. The main beam parameters are as follows: beam energy, beam intensity, beam profile, beam divergence, and the neutralization efficiency. For improved monitoring of the beam parameters, a beam profile monitor (BPM) from the National Electrostatics Corporation (NEC) has been installed in the Li beam line at JET. In the NEC BPM, a single grounded wire formed into a 45° segment of a helix is rotated by a motor about the axis of the helix. During each full revolution, the wire sweeps twice across the beam to give X and Y profiles. In this paper, we will describe the properties of the JET Li beam as measured with the BPM and demonstrate that it facilitates rapid optimization of the gun performance.