壁电流探测器在中国散裂中子源快循环同步加速器调束中的应用

快循环同步加速器（RCS）是中国散裂中子源（CSNS）的重要组成部分。负氢粒子束经直线加速器加速至80 MeV,剥离成质子束注入至RCS环并加速累积至1.6 GeV引出打靶。束流通过安装在RCS环的壁电流探测器（WCM）感应得到束流的强度信息,环高频与环主二极磁铁的失配会导致束流的实际振荡偏离理论预测。本文通过对WCM的数据进行分析得到了纵向工作点、束流的实际振荡频率、束团的电荷量、束团的形状变化等信息,方便了加速器的调束,并对参数测量中的测量误差进行了分析。     

壁电流探测器在中国散裂中子源快循环同步加速器调束中的应用

快循环同步加速器(RCS)是中国散裂中子源(CSNS)的重要组成部分。负氢粒子束经直线加速器加速至80 MeV,剥离成质子束注入至RCS环并加速累积至1.6 GeV引出打靶。束流通过安装在RCS环的壁电流探测器(WCM)感应得到束流的强度信息,环高频与环主二极磁铁的失配会导致束流的实际振荡偏离理论预测。本文通过对WCM的数据进行分析得到了纵向工作点、束流的实际振荡频率、束团的电荷量、束团的形状变化等信息,方便了加速器的调束,并对参数测量中的测量误差进行了分析。     

同步加速器束流能量自动切换控制系统

带电粒子放射治疗中3D主动治疗方式需要不同的束流能量照射不同的病灶切面,这就需要同步加速器控制系统能实现多级束流能量的自动切换控制并提供接口对接治疗计划进行自动变能控制。本文开发了同步加速器束流能量切换控制系统,同步加速器的前端服务器中存储着执行1个同步加速器加速周期所需的全部控制数据集,其中控制数据通过索引标号对其进行区分,同步事例信息是同步加速器多级束流能量切换的触发信号。当前端控制器被同步时间系统的同步事例触发激活后,从DSP波形发生器的SDRAM空间中读出磁铁电源、高频等控制数据进行数据切换。同步事例信号包含同步触发信息、束流能量控制数据的索引信息和控制数据的更新操作信息。多级束流能量自动切换控制系统能实现255级束流能量间自动切换控制（碳束能量在50～500 MeV间切换,步长可控制在1.77 MeV）,完全能满足实际中碳束能量在50～500 MeV间以10 MeV为步长的自动切换控制。     

世界上第一个强子电子环装置落成

【英国《自然》周刊1990年11月22日报道】强子电子环加速器(HERA),即世界上第一台电子-质子碰撞机于1990年11月初在汉堡德国电子同步加速器附近落成,目前正在为启动作准备工作。6336米长的椭圆隧道座落在汉堡Bahrenfeld地下20米深处。预期该装置在1991年春季出第一批理论能量值的束流,并在春季进行首次质子一电子碰撞试验。质子将被循环加速到     

中国散裂中子源快循环同步加速器射频系统的设计与研制进展

研制了大功率宽带快速扫频射频系统,其用于中国散裂中子源（CSNS）快循环同步加速器（RCS）中,主要包括铁氧体加载谐振腔、射频功率源、偏流源和低电平控制系统。射频系统工作重复频率为25 Hz,扫频范围为1.022～2.444 MHz,单个腔体（双加速间隙）可提供最大30 kV加速电压。两级的调谐控制能解决快速扫频过程中的系统失谐问题,采用束流前馈、直接反馈等多种技术手段可对束流负载效应进行补偿。     

千兆电子伏重离子加速器——兰州冷却储存环

能量达千兆电子伏的兰州重离子加速器冷却储存环HIRFL-CSR,是一个集加速、累积、电子冷却及内外靶实验于一体的多功能双冷却储存环同步加速器系统,由主环CSRm和实验环CSRe构成,并以兰州重离子回旋加速器系统HIRFL作注入器。CSR将重离子束的能量从兆电子伏提高到千兆电子伏,同时利用空心电子束冷却技术将束流的动量分散及发射度降低1~2个数量级,并提供多种类的高电荷态重离子束以及放射性次级束(RIBs),以开展更高精度的物理实验及更广范围的应用研究。兰州冷却储存环于2006年建成并投入运行,实现了剥离注入与多圈注入、空心电子束对重离子束的冷却与累积、变谐波宽能区同步加速、等时性环型谱仪、RIBs的产生与收集以及重离子束的快慢引出,并实现了高能重离子束的空心电子束冷却,使得重离子束的动量分散降低到10^-5量级,而发射度收缩到0.1πmm•mrad以下。同时,完成了短寿命近滴线核素的高分辨质量测量物理实验及高能重离子束深层治癌的临床应用实验。     

基于CSNS壁电流探测器数据采集的定制示波器的研制

壁电流探测器是观测粒子加速器瞬时束流信息的一种重要手段。中国散裂中子源（CSNS）快循环同步加速器中安装了两个壁电流探测器,其中一个壁电流探测器用来测量束流的微脉冲信息。本文介绍了壁电流测量系统的硬件和软件,鉴于传统示波器在垂直分辨率及存储深度等方面的局限性,提出了一种定制示波器来进行壁电流的信息读取,并利用LabVIEW编程实现了20 ms内束流信息的宏脉冲读取及微脉冲结构的分析,使用同步的环高频信息分析能得出快循环同步加速器中双束团关于相位、圈数、每圈束团形状等方面的相关信息。     

美国费米实验室获得512GeV束流

【法国《核电》1983年7月6日报道】美国物理学家最近用费米实验室的超导电磁铁加速器首次获得512GeV 的束流。该大型超导加速器的加速环总长6,400     

紧凑型中高能同步加速器的物理设计

本文采用束流光学匹配软件优化组合磁铁布局得到一种紧凑型的同步加速器。该加速器具有周长短、磁铁孔径小、束流品质高等优点。注入和引出设计是此同步加速器的关键点,基于Matlab/AT开发了模拟软件,模拟研究注入和引出相关束流动力学问题。研究结果表明,该同步加速器束流品质优、注入效率高、引出束流损失低。该同步加速器可满足航天、材料和生物等多方面研究。     

NDZ-20医用电子直线加速器的注入系统

文章介绍了NDZ-20医用电子直线加速器的束流注入系统的结构和特性。电子枪为轰击型的皮尔斯电子枪。漂移管上的预聚焦线圈、偏掉线圈、导向线圈和束流前沿切割线圈用来实现对电子束的多种控制,实现加速器的ARC,ADC和BLC运用,以保证加速器运行的稳定性和可靠性,改善反馈加速器的能谱。     

增强器共振补偿方案

强流重离子加速器的增强器用于强流重离子的极限累积和加速,其强流束产生的空间电荷效应使束流的工作点分布发散和漂移,并在工作点跨越低阶共振时造成离子束发射度增长甚至带来较大的束流损失。为消除低阶共振对离子束的不利影响,采用多极磁场来对6个低阶共振进行补偿。本文分析了增强器工作点附近的低阶共振,探讨了共振禁带的贡献项及相应的补偿方案,并通过数值模拟验证了增强器的共振补偿方案。结果表明,由增强器色品校正六极场引起的共振增强能通过补偿六极场进行消除,这将有利于增强器强流重离子束的实现。     

Floating Ring Stabilization System

The necessity of magnetically levitating a superconducting, current carrying ring without mechanical supports requires an electrical stabilizing system. The ring, when supported, has only one equilibrium position and this position is one of unstable equilibrium. The ring is free to move with up to six degrees of freedom. Two degrees are dictated by the ability of the ring to move in any direction in the plane of the ring. Additionally, the ring can be tilted requiring three more reference points to determine a new plane. The sixth degree of freedom is the ability of the ring to rotate upon its own axis, but because external forces tending to cause this rotation can, in principal, be eliminated, a restoring supply is not provided. Each of the five identical stabilizing supplies in this system has a feedback loop composed of the following segments. The position detector element is an optical head which sends a light beam across an optical edge on the ring, the reflection of which is sensed on a photo diode. This diode voltage signal, proportional to the ring position, is the input to an amplifier whose output is a signal proportional to position, velocity and ring acceleration. A 50 volt, 100 ampere, bidirectional dc transistor power supply is activated from this signal which in turn powers the appropriate stabilizing coil located near the floating current carrying ring.     

Physical Startup of the TWAC Storage Ring

C⁶⁺ ions with energy 200 MeV/nucleon have been accumulated in the chamber of the ring magnet of the U-10 proton synchrotron used as a storage ring in the TWAC setup. A C⁴⁺ ion beam from the laser source was first accelerated in the I-3 injector up to 1.3 MeV/nucleon and in the UK booster synchrotron up to final energy with periodicity 3.5 sec. Ions have been accumulated in U-10 using the multiple charge-exchange injection scheme C⁴⁺ C⁶⁺. An increase in the ion intensity in the accumulator has been observed during several injection cycles. Experimental data on the attained parameters of the accumulated beam are presented, and the status of the optimization of the accumulation regime is discussed.     

兰州重离子加速器冷却储存环射频堆积过程模拟

考虑了重离子冷却储存环中粒子纵向相振荡的运动特性及电子冷却的作用,模拟兰州重离子加速器冷却储存环（HIRFL－CSR）主环中的射频堆积过程,给出了高频参数在射频堆积过程中随时间的变化曲线,为高频腔的设计及机器运行时的参数预置了理论依据。     

基于导频的储存环束流位置测量处理器研制

稳定的束流轨道对于同步辐射光源的性能至关重要,规划中的合肥先进光源是第四代衍射极限储存环,其亚微米级的束流轨道稳定度需要束流位置测量精度达到100 nm级别。本文基于国产化芯片,研制了带有导频补偿机制的束流位置测量处理器,主要包括导频模块、模拟前端模块、数字处理模块和嵌入式工控模块。输入信号经过导频模块和模拟前端模块调理,在数字处理模块通过带通欠采样原理实现模数转换,数字信号在现场可编程门阵列（FPGA）内经过下变频、滤波抽取、坐标旋转数字计算（CORDIC）模块以及差比和算法等处理后获得束流位置信息,嵌入式工控模块实时传输束流位置信号,与加速器控制系统通信。目前设计的束流位置处理器完成了实验室离线测试和束流测试,测试结果表明,当输入信号幅度在-55～5 dBm范围时,束流位置测量处理器的快获取数据（FA data）和慢获取数据（SA data）分辨率分别好于120 nm和70 nm,满足设计要求。     

Numerical Simulation of the Effect of the Beam Space Charge on the Acceptance of a Storage Ring

A model based on the assumption that there exists a stationary particle distribution in the space of invariants is used to investigate numerically the effect of the space charge of a beam in storage rings. The model is used to develop a computer code that makes it possible to use a personal computer to investigate the dependence of the acceptance on the beam current, betatron frequency, and other machine parameters. The structure of the code and the results obtained using it for the ACR storage ring (RIKEN, Japan) and the accelerator-storage system at the Institute of Theoretical and Experimental Physics are described. The computational results show that this computer code is an effective tool for calculating and optimizing the parameters of high-current storage rings.     

兰州重离子加速器冷却储存环高频加速系统

文章介绍兰州重离子加速器冷却储存环主环用于加速粒子的高频加速系统。加速系统的频率范围为0. 25~1.7MHz，最高峰值电压为8.0kV。高频腔体的固有谐振频率通过调节绕在腔体加载的铁[JP2]氧体材料上的偏磁电流来改变，所加载的铁氧体材料为600HH。高频腔体内的真空度达到3×10^-9Pa，高频发射机的最大输出功率为30kW，高频系统的控制采用基于PCI总线技术，它提供所有高频系统控制及监测功能。     

Linear hybrid simulations of low-frequency fishbone instability driven by energetic passing particles in tokamak plasmas

A linear simulation study of energetic passing particle-driven low-frequency fishbone instability in tokamak plasmas has been carried out using the global kinetic-MHD (magnetohydrodynamics) hybrid code M3D-K. This work is focused on the interaction of energetic passing beam ions andn=1 mode with a monotonic safety factorqprofile andSpecifically, the stability and mode frequency as well as mode structure of then=1 mode are calculated for scans of parameter values of beam ion beta, beam ion injection energy, beam ion orbit width, beam ion beta profile, as well as background plasma beta. The excited modes are identified as a low-frequency fishbone with the corresponding resonance ofwhereis the beam ion toroidal transit frequency andis the beam ion poloidal transit frequency. The simulated mode frequency is approximately proportional to the beam ion injection energy and beam ion orbit width. The mode structure is similar to that of internal kink mode. These simulation results are similar to the analytic theory of Yuet al.     

HIRFL-CSR束流加速过程的模拟

考虑储存环内离子在纵向相空间的运动特性,模拟了ＨＩＲＦＬ－ＣＳＲ主环内重离子的加速过程。给出了粒子不同时刻在纵向相空间的分布,在给出主磁场的运行模式后,得到高频率频率、同步相位、高频电压、束流长度、动量散度以及粒子能量随时间的变化等主要参数。     

Investigations on single-phase natural circulation loop dynamics. Part 3: Role of expansion tank

Expansion tank is an important component of all single-phase natural circulation loops. The tank serves the twin purposes of venting the air out during the loop filling and accommodation of the swells and shrinkages of the loop fluid during the transient. In the present study, experimental investigations have been carried out in a rectangular single-phase natural circulation loop to bring out the role of expansion tank in loop dynamics. The results on loop stability and transient behavior are discussed. The experimental investigations show that there is significant amount of heat exchange between the main loop fluid and the expansion tank fluid. First, the results of experimental studies are presented. The different flow regimes observed in these experimental investigations are discussed. Next, a model is presented for taking into account the heat exchange between the main loop fluid and the expansion tank fluid. Finally, the model is applied to simulate the dynamic behavior of different single-phase natural circulation loops. The investigations carried out in this study have helped in resolving the issue of hysteresis observed in these loops.