合肥国家同步辐射实验室电子储存环束流损失监测系统中的几个物理问题

电子储存环中损失的束流电子，在撞击真空室壁时，引起“电子-γ-电子”簇射，在撞击点的下游，真空室的外表面形成次级电子（shower电子）的分布。通过探测这些shower电子，可以知道上游某处的束流损失状况。“合肥国家同步辐射实验室加速器二期工程”中的电子储存环束流损失监测系统，就是利用这个原理。在分析了原有加速器束流损失监测系统的缺陷并对国际上各大型加速器进行了调研的基础上，对该系统中的探测器选型、探测器安装位置的选择以及系统的整体结构等物理问题作了阐述。     

NSRL中的BPM前端电子学系统研究

介绍了国家同步辐射实验室二期工程中的束团位置监测的前端电子学系统原理、结构和实验结果。利用此系统可以把确定束团位置坐标的模拟信号引出。供数据采集分析。     

基于EPICS的数据采集系统

本文介绍了在加速器控制系统和束流测量系统中广泛应用的EPICS开发平台，并在Redhat 6.2操作系统上建立了一个基于EPICS的数据采集系统，利用该系统实现了束流位置探头的快速标定。     

数字BPM系统中模拟调理电路的研究

全数字化束流位置测量系统(Digital Beam Position Monitor,DBPM)将应用于上海同步辐射光源(Shanghai Synchrotron Radiation Facility,SSRF),其中模拟调理电路是DBPM系统重要组成部分。BPM探头输出的4路高频窄脉冲信号(重复频率499.654 MHz,脉宽200 ps)通过模拟调理电路进行滤波及自动增益调整,然后送至ADC进行模数变换,在系统中的数字处理模块进行处理后最终得到束流X、Y方向位置信息。系统电子学测试表明:此DBPM系统在输入信号动态范围为-40～10 dBm情况下,X、Y方向位置分辨率好于10μm,满足逐圈(694 kHz数据更新率)位置分辨要求。     

辐射场监测在合肥光源中的应用研究

合肥光源于近期完成了重大升级改造,对电子加速器和储存环的结构进行了重新调整,同时升级了辐射监测系统和束流损失监测系统。除了具备基本的机器保护与人员安全防护功能以外,通过加入时间信息、位置信息和加速器运行参数信息,新监测系统还具有一定的机器诊断能力,对加速器的调机和维护有辅助作用,同时也加深了对辐射源项的了解,对优化防护措施有指导意义。     

快速冲击磁铁系统的研制

合肥同步辐射光源（Hcfci Synchrotron light sourcc,HLS)的某些实验需要长时间间隔同步辐射（Synchrotronradiation)光脉冲，但是目前HLS还不能满足这些要求。因此提出在HLS储存环上采用局部凸轨的方法来延长SR光脉冲的时间间隔。为此设计了快速冲击磁铁系统，其中脉冲调制器采用脉冲成型线(Pulse Forming Line）技术设计；冲击磁铁为空芯电流板结构的磁铁。初步实验表明，快速冲击磁铁系统的设计符合实验要求。     

一种实现远程计算机控制的定时系统的研制

介绍了一种基于Client／Server网络通讯结构和RS232串行通信协议的远程计算机控制系统。该控制系统用于国家同步辐射实验室逐圈束流位置测量(Turn-by-Turn)系统的定时系统中。     

用于粒子加速器位置监测的静力水准系统与线位置探测器的比对研究

本文搭建了一套由温湿度传感器、激光位移传感器、高精度位移平台组成的实验系统。采用控制变量法,分别以环境因素及位移为变量,对固定在同一位移平台的静力水准系统(HLS)与线位置探测器(WPS)进行两组实验。实验结果表明：温度是影响HLS测量精度的主要因素,通过温度补偿,可得到较为精确的结果;湿度变化改变张紧线的下垂量,从而影响WPS的测量精度。在环境稳定的情况下,WPS与HLS对同一点的测量结果差值的均方根误差最大为0.003 37 mm,在误差允许范围内,因此两者可组合使用。     

Development and application of the new BPM system data processing program at Hefei light source

A data processing program has been applied for the new beam position monitor (BPM) system of the storage ring at Hefei Light Source (HLS). The new BPM system in the upgrade project will be equipped with Libera Brilliance BPM processors to replace the old Bergoz MX-BPM processors. The embedded Linux system on Libera has completed some important work, including instrument status check,data acquisition, position calculation, EPICS IOC data release,and so on. A new EPICS record type has been developed to recalculate the beam position with log-ratio method. The property of the new position data was analyzed in the time and frequency domain. The results show that the rms value of beam position measurement resolution can be up to submicron. Preliminary studies have been carried out on the measurement of the tune and the beam lifetime with this new BPM system.     

An embedded single-board computer for BPM of SSRF

An embedded single-board computer (SBC) system based on AT91RM9200 was designed for monitoring and controlling the digital beam position monitor system of Shanghai Synchrotron Radiation Facility (SSRF) through the Virtex-4 FPGA in the digital processing board.The SBC transfers the configuration commands from the remote EPICS to the FPGA,and calculates the beam position data.The interface between the FPGA and the SBC is the Static Memory Controller (SMC) with a peak transfer speed of up to 349 Mbps.The 100 Mb Ethernet is used for data transfer between the EPICS and SBC board,and a serial port serves as monitoring the status of the embedded system.Test results indicate that the SBC board functions well.     

SHINE腔式BPM系统射频信号调理前端研制

基于低温超导直线加速器的上海硬X射线自由电子激光装置（SHINE）需1个分辨率可达200 nm的束流位置测量系统,以实现电子束与光子束在波荡器中的紧密相互作用和能量交换。现已研制的束流位置测量系统不能完全满足上述要求,为此,基于对关键技术指标的分配,设计研制了一个由C波段腔式探头、低噪声系数的单路下变频至低中频的射频信号调理前端以及专用数字信号束流位置处理器构成的CBPM系统样机。而作为连接腔式探头和数字信号采集电子学之间的桥梁,射频信号调理前端（radio frequency front end, RF前端）的结构和性能也直接决定了CBPM系统的性能。本文从SHINE对CBPM系统的整体需求为出发点,分析了系统对射频信号调理前端的指标分配,提出了一种放大器开关切换型RF前端的方案设计,并成功搭建了1套可模拟束流条件的离线全锁相采样测试平台。此外,在上海软X射线自由电子激光装置（SXFEL）中搭建了测试平台并完成了射频信号调理前端的带束性能评估,束流实验结果表明,在束团电荷量为100 pC、系统动态范围在±100 μm的条件下,采用腔式探头射频信号一分二的评估方法,位置分辨率可达71 nm,优于设计指标需求。     

Turn-by-turn system and its primary experiment at HLS

During the Phase II project of NSRL, a turn by turn BPM (Beam Position Monitor) system is proposed for storage ring diagnostics which engages log-ratio electronics circuit to measure machine properties of the HLS (Hefei Light Source) storage ring. The log-ratio processor works at 408 MHz, twice the RF frequency of HLS. Modern logarithmic amplifiers with wide dynamic range, great bandwidth, good logarithmic conformance, and low cost are attractive for beam position measurements. Injection kicker and the stripline-electrode resonant exciting methods are used to excite beam for nonlinear beam dynamics and phase space studies of stored beam. Up to 2 seconds of data acquisition is ensured. In this paper we present the performance of each component and preliminary test results of the turn-by-turn BPM system.     

100MeV直线加速器束流位置探测器系统设计

100MeV直线加速器束流位置探测器系统包括BPM(Beam position monitor)、BPM前端电子学、基于束流的准直模块(Beam based calibration,BBC)、高频信号切换模块和AD模块.本文详细介绍了BPM前端电子学和数据采集系统设计.最后给出了在100MeV直线加速器中测试的BPM系统性能.     

TC-SCAN组合移动式数字DR成像系统图像动态校正技术研究

组合移动式数字DR成像系统中,由于门架在轨道上运行过程中发生变形,生成的图像中产生横纹,在轨道很长的滚装车辆检测系统中这种横纹现象更明显。介绍了这种横纹产生机理,研究了相应的校正消除方法,并设计了实用的动态校正方法。     

Design and test of the KSTAR vacuum pumping system

The Korea Superconductor Tokamak Advanced Research (KSTAR) device is a tokamak mainly composed of a vacuum vessel, superconducting magnets, and cryostat. The internal volume of the vacuum vessel is about 110 m³ with a target pressure of 1 × 10⁻⁶ Pa, while the volume of the cryostat is 450 m³ with a target pressure of 5 × 10⁻³ Pa. To attain these target pressures, two identical vacuum pumping systems consisting of dry pumps, mechanical booster pumps, turbo-molecular pumps, and cryopumps were installed. The control system of the vacuum pumping systems was built using the experimental physics and industrial control system (EPICS), which has various merits such as easy access, convenient extension and flexible integration. The pump-down test of the pumping ducts was successfully executed under the control of the EPICS system.     

A review of geometric calibration for different 3-D X-ray imaging systems

A precise knowledge of geometry is always pivotal to a 3-D X-ray imaging system,such as computed tomography(CT),digital X-ray tomosynthesis,and computed laminography.To get an accurate and reliable reconstruction image,exact knowledge of geometry is indispensable.Nowadays,geometric calibration has become a necessary step after completing CT system installation.Various geometric calibration methods have been reported with the fast development of 3-D X-ray imaging techniques.In these methods,different measuring methods,calibration phantoms or markers,and calculation algorithms were involved with their respective advantages and disadvantages.This paper reviews the history and current state of geometric calibration methods for different3-D X-ray imaging systems.Various calibration algorithms are presented and summarized,followed by our discussion and outlook.     

空间带电粒子谱仪性能测试及能量刻度

采用金硅面垒探测器及CsI(Tl)探测器设计制作了一套△E-E型探测空间粒子的望远镜系统,利用α粒子、质子、氧离子、铁离子4种粒子对该望远镜系统和电子学系统进行性能测试和能量刻度。电子学的增益系统分为三挡,分别为1.0、1/3和1/12.75。实验结果表明:对于α粒子,采用1/3挡,在△E_1和△E_2探测器中每道能量分别是H_1=0.107 MeV和H_2=0.123 MeV。对质子能量的刻度,采用1挡,每道能量H值为0.016 7 MeV,这个H值几乎不随能量变化,在CsI探测器中,每道能量H为1.047 MeV。对氧离子的能量刻度采用1/12.75的挡别,刻度出每道能量是1.11 MeV。在探测器中,沉积能量高于50 MeV,电子学系统进入饱和状态。对铁离子的标定结果与氧离子的结果相同。