Methods of measurement for the beam-based alignment system in HLS

The beam-based alignment system is given in HLS （Hefei Light Source）, in which a switchable shunt resistor was installed on quadrupole to bypass a small percentage of the magnet current. The system can measure BPM-to-quadrupole offset which can be used to position the beam in the magnetic center of quadrupoles. In measurement, some methods （ linear fitting with single corrector, parabola fitting with single corrector, linear fitting with local bump, and parabola fitting with local bump ） are used. These measurement results are given, and compared among the methods mentioned above.     

HLS脉冲四极磁铁注入方法设计与研究

介绍了一种采用脉冲四极磁铁实现储存环束流注入的新方法.通过物理计算和注入过程数值模拟研究,确定了储存环上安装脉冲四极磁铁的位置和强度,并通过模拟计算评估了注入过程中注入束流存活效率和对储存束流的影响,证明了在合肥光源采用脉冲四极磁铁完成束流注入过程的可行性.     

合肥光源的工作点测量系统

合肥 8 0 0MeV电子储存环的工作点测量系统采用扫频激励法进行工作点测量 ,它由条带束流位置检测器、180 0 的魔T、混频器、带扫频信号输出的频谱分析仪、功率放大器和束流激励电极等构成。该系统的测量精度约为 1× 10 4 。利用该系统进行了机器的校正色品测量 ,给出了工作点和色品的测量结果。     

HLS直线加速器条带束流位置检测器基于对数比方法的标定

对合肥光源（HLS）直线加速器（LINAC）的束流位置测量系统进行改造，设计并加工了非拦截型、高精度的条带电极束流位置检测器（BeamPositionMonitor,BPM）。安装前，通过定位精度小于5μm的电控位移平台，采用具有更大动态范围和线性度的对数比而非传统的差和比的处理方法，对条带束流位置检测器进行标定。本文介绍了标定平台、对数比处理系统以及自动控制标定程序，给出了基于对数比方法的标定结果。该条带电极束流位置检测器的水平方向和垂直方向的灵敏度分别为1.55dB/mm和1.48dB/mm，束流位置分辨率为42μm，电中心相对于机械中心的偏差为（0.212，0.450）mm。     

合肥光源基于虚拟仪器技术的束流诊断系统

介绍了合肥光源利用虚拟仪器技术构成的束流诊断系统,包括基于GPIB总线构成了储存环直流流强测量系统,基于VXI总线构成了束流闭轨测量系统,基于PCI总线构成了束流横向截面测量系统,基于网络化虚拟仪器技术构成了在线束团长度测量系统和同步光位置测量系统.软件采用Lab-VIEW编程,极大地减轻了开发的工作量.     

用20GHz数字取样示波器测量束团长度

介绍了采用２０ＧＨｚ数字取样示波器在合肥８００ＭｅＶ电子储存环中测量束团长度的方法和原理。给出了束团长度及其伸长效应的测量结果。在流强为２－１２４ｍＡ情况下，实测束团长度为３．８０－１０．３３ｃｍ；流强大于１５ｍＡ，束团伸长效应明显。     

400 kV强流中子发生器的物理设计

对400 kV强流中子发生器进行了物理设计。采用Poisson/Superfish软件对中子发生器高压电极和加速管的电场分布进行了模拟,结果显示,各关键区域的空间电场最大值远低于击穿电场限值。以强流束旁轴包络方程为基本模型,发展了强流束传输系统束包络的计算机模拟程序IONB1.0,模拟了中子发生器传输系统中40 mA的D束流包络。结果显示,设计方案中所采取的两间隙高梯度加速结构有较强的聚焦性能,能有效抵消强流束空间电荷效应造成的束流发散,加速管出口处的束包络半径约3 cm,由加速管出口处的空间电荷透镜和三重四极磁透镜组成的传输系统能将束流聚焦在约140 cm处的靶上,且束斑直径小于2 cm。     

Tidal effects on hydrostatic leveling system used in high precision alignment of particle accelerator

Hydrostatic leveling system（HLS） is widely used in precision engineering survey,especially the alignment of particle accelerator,and the tidal effects on the measurement accuracy of HLS is non-ignorable.thus studies on tidal effects on the HLS is vital.A set of HLS was installed in Jingxian seismostation for verifying the methods to handle the tidal effects on the readings of HLS.Harmonic analysis of the data recorded by HLS and DSQ water tube clinometers in Jingxian seismostation and contrastive analysis of the results are completed.The tilt tide can be well reflected in the data of the both instruments and the results are both reliable.The reasons of the difference between the results are analyzed in this paper.Besides,a validation study based on the measurement data of the HLS used in SPring-8 storage ring for tidal correction on the reading of HLS is completed.The research establishes a foundation for HLS to be applied in micron-level precision alignment of particle accelerator in the future.     

Libera Photon在合肥光源同步光位置测量系统中的应用

合肥光源新引进了IT公司的新一代光位置信号处理器Libera Photon,其采用嵌入式EPICS IOC,极大地提高了数据的传输效率,经测试,该处理器的分辨率好于0.07 μm。同时,自主研制开发了相配套的时钟分配器以及远程软件控制程序,并将新同步光位置信号处理系统用于原有的双丝型光位置探测器进行了初步的应用研究,测试得到的同步光位置信息与相近的BPM Q8E所测得的束流位置信息变化趋势一致,说明Libera Photon能够很好地进行同步光位置信息的测量。     

上海光源二期工程的垂直发射度研究

上海光源二期工程正在设计一个新的磁聚焦结构,它包含双斜插入件、超导二极铁以及超导扭摆器等新的元件。光谱亮度是表征同步辐射光源性能的一个重要参数,通过降低垂直发射度的方式来提高亮度是一种简便可行的方法。首先分别模拟和计算了各类磁铁准直误差对垂直发射度的影响,然后采用奇值分解法校正了误差引起的闭轨畸变,最后使用60个斜四极铁来校正垂直发射度。结果表明,在上海光源二期工程的磁铁准直公差与目前正在运行的上海光源相同的条件下,六极铁垂直准直误差对垂直发射度的影响最大;用60个斜四极铁来校正垂直发射度,能使耦合度保持在0.5%以下。     

合肥光源200MeV直线加速器束流流强测量系统的改进

用ＰＣ机经扩展机箱完成对８路束流信号的采集,处理,并可同时显示,打印全部８路束流流强信号于一幅,也可任选其中一路帮单幅放大显示,此设备提高了直线加呸器束流流强信号的测量精度,并方便了直线加速器调机人员的操作。     

The nuclear microprobe at the University of Arizona

A nuclear microprobe has been operational at the University of Arizona since early 1994. It utilizes a magnetic quadrupole doublet (model QL-300 from Microscope Associates, Inc.) with an 11 mm diameter aperture and lens lengths of 6 cm each. The magnetic pole tips are electrically insulated to enable electric rotational alignment and beam rastering by application of varying voltages to the pole tips. Ion beams are obtained from a 5.5 MV model CN, High Voltage Engineering Corp. Van de Graaff accelerator with a Penning type ion source. Present mininum beam spot size is about 2 μm obtained with a 4 MeV H₂⁺ beam with a current of about 40 pA. To date, the instrument has been successfully used to map concentrations of Hg, Cr, and As in rabbit renal slices using PIXE.     

Development of a PSD-based photon beam position measurement system

As an important part of the beam diagnostic system, the synchrotron light beam position measurement has a very high value in the high quality and high stability light source applied research. A new photon beam position monitor based on position-sensitive detector (PSD) has been developed to measure the photon beam position in vertical and horizontal directions at the same time at HLS (Hefei Light Source). The new PBPM based on the PSD has fast response speed, high sensitivity and wide dynamic range. This PBPM system also includes the C4674 signal processing circuit, NI USB-9215 data acquisition device and the LABVIEW data acquisition program. This PBPM system has been calibrated vertically and horizontally on-line, and then has been applied in the beam line B3EA of HLS to measure the position of the synchrotron light. As the results shown, the resolution of the system is better than 3 mm.     

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.     

一种波荡器段间四极铁远程精密调节机构的研制

自由电子激光(Free Electron Laser,FEL)装置是一种以相对论高品质电子束作为工作介质,在周期磁场中以受激发射方式放大电磁辐射的新型激光源。FEL装置中的四极铁中心相对于束流中心线的高精度就位与否将直接影响束流的品质,上海软X射线自由电子激光装置和大连极紫外相干光源装置的波荡器段间四极铁均采用基于束流准直方法(Beam based alignment,BBA),需要可远程精密调节四极铁位置的机构。BBA四极铁远程精密调节机构主要由可远程精密定位的电移机构和控制系统构成。电移机构采用精密滚珠丝杠驱动的滑块组合机构,可实现垂直于束流的水平和竖直高度方向的二维调节。本文简单描述了BBA四极铁远程精密调节机构的机械设计,对BBA四极铁远程精密调节机构的测试方法及结果进行了详细分析。该系统集成测试结果表明,机构运动过程中采用光栅尺进行反馈,其定位精度和重复性均达到了设计指标要求。     

合肥光源注入过程中束流负载效应和束流强度限制

根据储存环高频系统束流负载理论，研究计算了合肥光源注入过程中高频系统的大失谐角工作模式和调谐工作模式。综合考虑两种模式利弊，给出了更为灵活的注入模式。对于合肥光源，只要新高频系统参数设置合理，束流可顺利注入积累到设计值300mA以上。     

合肥光源超导扭摆磁铁模式下线性光学参数补偿

合肥光源是1台专用真空紫外光源，为拓展同步辐射用户可用光范围，在储存环上安装了1台6T的超导扭摆磁铁。超导扭摆磁铁给储存环光学参数带来很大扰动，造成工作点漂移和β函数畸变。最初，在补偿工作点漂移后，成功地存储了束流并产生了硬X射线，但该运行模式下束流寿命短，严重影响其它实验线站的实验工作。在合肥光源二期工程中，重新进行了超导扭摆磁铁补偿计算，在不改变目前储存环磁铁和电源的基础上，同时补偿工作点漂移和β函数畸变，大幅度地改善了束流寿命。     

射频四极场加速器低能强束流传输注入系统的实验研究

对加速器驱动的次临界系统（ADS）的射频四极场（RFQ）加速器的低能强流束流传输系统进行实验研究,给出了在强流离子束束腰附近测量束流参数的方法,并测量了强流质子注入系统在RFQ入口处的束流参数。目前,该系统已成功地应用于强流射频四极场质子加速器中。     

RF tuning and beam commissioning of CW RFQ for China-ADS Injector-I

A 325-MHz continuous-wave(CW) four-vane radiofrequency quadrupole(RFQ) is employed in Injector-I of the China Accelerator-Driven Subcritical System. The radiofrequency tuning and beam commissioning were performed from January 2014 to January 2017. In a cold test, a stability study showed that the design of the segmented resonantly coupling and dipole stabilizer rods can shift the harmful quadrupole and dipole mode from the fundamental mode to above 2.6 MHz. We also found a simplified tuning method for the field unflatness, involving changing the inserted length of a few plug tuners. For achieving CW-beam commissioning, two full-size RFQs were constructed successively. The commissioning results indicate that the beam transmission rate decreased by approximately 3% as the normalized field unflatness decreased by 1%. A 10-MeV CW proton beam with an average beam current of 2.1 m A was achieved at the target of Injector-I, and the output beam energy of the RFQ was3.18 MeV.     

束流发射度的测量

在束流输运系统中,快速而精确地测定束流的发射度,对于提高束流传输效率、调节并保证束流达到预期的场所,是十分重要的。通常在测定束流发射度时采用移动缝隙法或电磁偏转方法。这些方法不仅需要附加一些较复杂的装置,而且测量时费时费力。特别是这些方法都必须采用缝隙装置,在测量时截留了大部分束流流强,因而必须强迫冷却,而在测量后,这些缝隙装置又带有很强的放射性。除了以上这些问题以外,由于束流在缝隙上的散射,又使测量结果的误差增大。Fermi实验室的E.R.Gray、CERN的G.Baribaud和C.Metzger曾用测量束流剖面的方法来测定束流的发射度。他们测量一段漂移空间内三点的