BEPC II直线加速器数字BPM前端调理电路的研制

针对北京正负电子对撞机改造工程（BEPC II）直线加速器束流位置测量电子学系统故障率上升这一现状,结合BEPC II直线加速器束流参数以及BPM电子学ADC芯片带通采样的需求,设计了隔离度高、幅相一致性好的数字BPM射频前端电子学模块。数字BPM电子学系统采用MicroTCA 4.0系统架构,以FPGA作为主控制器,基于EDA软件开发设计。重点介绍了射频前端电子学模块中射频功率放大器、数字可调衰减器、带通滤波器等设计和实验室及在线测试结果。BEPC II对撞模式下,使用正电子束流,完成电子学系统在线测试,x方向位置测量精度约为38.46 μm,y方向位置测量精度约为26.16 μm,其测量精度和系统稳定性优于商用模拟BPM电子学模块,能够满足BEPC II直线加速器束流位置测量需求。     

合肥光源基于束流准直系统的控制软件设计

束流位置监测器(BPM)和与其相邻的四极铁之间的电偏移对于电子储存环轨道校正十分重 要。改变四极铁的强度,并通过测量轨道变化就能够计算出该四极铁的磁中心相对于相邻的BPM的电中心 之间的偏差。基于NSRL储存环的BBA硬件系统和EPICS控制系统,采用Labview平台开发出了BBA测量 的软件控制程序。由计算机控制四极铁的强度,连续测量后拟合得到四极铁的磁中心与相邻BPM的相对偏 差,测量精度可以达到100μm。     

熊猫型保偏光纤定轴仿真研究

应用光波导理论分析了保偏光纤的POL定轴方法的基本原理.根据熊猫型保偏光纤的折射率分布模型,采用光束传播方法对影响熊猫型保偏光纤POL曲线分布的各种因素进行了仿真研究,包括不同观测平面、不同折射率分布(匹配型或非匹配)、是否加匹配液等因素.通过仿真结果与实验观测结果以及保偏光纤与单模光纤仿真结果比较,表明了理论分析与仿真方法的可行性.     

升级的合肥光源闭轨测量系统及其应用

 描述了合肥同步辐射光源二期工程中，电子储存环升级的闭轨测量系统及其在设备研制中的应用。介绍了性能稳定可靠的Bergoz束流位置监测电子学信号处理器。升级后的闭轨测量系统中处理电子学电路的束流位置分辨率可达1μm，系统误差小于10μm。整个测试系统的分辨率小于3μm。利用该高精度闭轨测量系统和基于束流准直系统完成了束流准直四极铁磁中心的测量，并和控制系统完成了储存环全环闭轨反馈校正试验。一个完整的束流位置监测系统已投入了在线运行，保障了为用户提供高稳定高品质的光源。     

New developments in design and applications for pelletron accelerators

Most of the developments over the last several years related to Pelletron accelerator are in the field of accelerator mass spectrometry (AMS) and other low beam current applications with the exception of a very high DC electron recirculation Pelletron. High precision AMS systems based on tandem Pelletrons from 500 kV to 5 MV terminal potential are now in use for routine high precision AMS measurements. Their performance will be reported. In addition, there has been significant advancement in the design of the multi-cathode SNICS source for the use of both gas and solid samples within a single source. The latest performance of these sources will be discussed. New diagnostics is being developed for very low beam currents. The latest design of the low current beam profile monitor (LCBPM) will also be presented.     

RF measurements of a C-band cavity beam position monitor

RF cold test of a novel C-band cavity beam position monitor (PBM) to be used in the SDUV-FEL Test Facility is described. The test results are presented and some characteristics discussed. The main parameters obtained are in reasonable agreement with the analytical estimations. Effective suppression of the common mode has been demonstrated. The position sensitivity over the test region of ±0.5 mm is about －21.58 dB/10 μm for the TM₁₁₀ mode and is linear in the central region of the BPM cavity.     

A New Approach to the Design of Hybrid Lenses for Integrated Optics

The Fresnel lens is one of the most extensively studied components in both classical and integrated optics. This structure is free from axial spherical aberration, but is heavily affected by both off-axis and chromatic aberrations. The latter can be compensated by introducing a refractive component, whose chromatic behavior is the opposite of that of the diffractive lens. This hybrid refractive-diffractive structure, however, is not able to deal effectively with off-axis aberrations, namely, with coma. In this work, a novel methodology for the design of corrected hybrid lenses is proposed which allows for correction of both chromatism and coma. The design method is based on a ray-optics variational approach which provides a range of possible achromatic solutions. An optimization procedure is performed by means of a series of beam propagation method numerical calculations which make it possible to simulate the lens operation and thus to find the best solution.     

平面光波导型单纤三向器的研究

利用光束传输法,分析设计了一种只由两个定向耦合器构成、能直接与单模光纤相耦合、易于集成的平面光波导（Planar Lightwave Circuit,PLC）型1.31/1.49/1.55 μm单纤三向器.该器件的输入输出弯曲波导和耦合区平行波导均采用光束传输法进行优化设计,并对器件的折射率进行了容差分析,获得了当两个定向耦合器的耦合长度分别为6 578 μm、3953 μm时,器件对各波长的隔离度均在47 dB以上,且插入损耗小于0.05 dB.     

畴反转结构片状集成4×4电光开关的设计与仿真

基于铁电体畴反转结构的电光偏转特性,设计了一种片状集成的4×4电光开关,其由四个结构相同的半抛物和四个抛物形微小偏转器集成构成.通过优化抛物形偏转器结构,给出了电光开关的设计参量,电光开关性能通过光束传播法进行仿真模拟,仿真结果表明该开关切实可行.实际应用中,系统误差可以通过电场调节补偿,使光路准确交换.该片状电光开关的整体尺寸为48 mm×2.2mm×0.5 mm(长×宽×高),最大使用电场约13.73 V/μm,适用于高速交换的光互连系统.     

用极坐标下的广角光束传播法计算分析弯曲波导

采用了极坐标下的广角BPM(Beam Propagation Method)对弯曲波导进行了计算模拟,并与极坐标下近轴BPM方法进行了比较,取得很好的结果.