CSNS/RCS次级准直器吸收体的冷却设计

作为CSNS/RCS横向束流准直系统的关键部件,次级准直器用于吸收经主准直器散射后不在预定轨道的束晕粒子,其工作原理决定了该设备要求满足强辐射环境下的稳定性、超高真空及高定位精度等要求。基于主准直器的设计及研制经验,对次级准直器结构方案及控制系统进行详细设计。针对关键部件吸收体,结合辐射防护分析结果,考虑水冷降温的方式,设计了控制程序,通过有限元分析软件ANSYS对其进行瞬态热分析,保证吸收体设计的可行性。     

CAFe DUMP前刮束器的设计研制

位于中国科学院近代物理研究所的超导直线加速器样机CAFe是一台质子超导直线加速器实验样机,围绕该装置的束流实验研究将为下一步设计研究加速器驱动次临界洁净核能系统(ADS)专用的超导直线加速器打下基础并提供经验。为了实现CAFe的10 mA束流指标,需要设计研制专门的束流收集器(DUMP)和对应的刮束器。本工作就CAFe DUMP前刮束器的研制进行了系统的设计和计算工作。刮束器面向束流侧的材料采用Al6063,确保束流轰击后的剩余放射性活度处于安全范围。基于蒙特卡罗粒子输运模拟,开展放射性核素及剩余剂量分析。结果表明,退役时刮束器外围剂量为可接受的百微希沃特每小时量级。通过ANSYS的热分析,计算了不同束流情况下刮束器的温度分布及温度变化,研究了刮束器在正常运行时移除热量的能力和在异常状况下应急保护的能力。计算结果表明,刮束器可以满足安全移除强流高功率束流束晕的设计需求。在CAFe高功率束流实验中,刮束器及DUMP运行正常,束流监测指标与设计一致,证明研制的刮束器实现了安全移除束晕、监测束流参数和保护DUMP的功能。     

FTO质子照相中扩束器的设计

 为了达到最佳的扩束效果和充分利用束流,从多次库仑散射角、能量损失和透射率这三个方面确定扩束器的材料类型。对均方根多次库仑散射(MCS)、质子能量损失和质子的透过率的研究都表明单位面质量下材料原子序数越大,扩束效果越好。再结合成本和适用性确定扩束器的材料为钨。同时,从探测器接收到的质子通量均匀而噪声影响小的角度,确定了扩束器的厚度。研究结果为：没有准直器的情形下,扩束器的厚度为3.1 cm;准直器角度为3.0 mrad时,扩束器厚度为2.4 cm。     

神光Ⅱ第九路光路自动准直系统研究

光路自动准直系统应用于惯性约束聚变的高功率激光装置中。针对神光Ⅱ第九路装置,设计了一套可行的准直方案,并在装置上进行了实验。实验结果表明,自动准直系统能够在15minSq顺利完成光路的自动调整,小口径近场调整准直精度小于±0．5mm,大口径近场调整准直精度小于±1．0mm,远场准直精度小于±1”,满足了装置的设计要求。     

环-靶站输运线末端准直器的研究

环-靶站输运线(RTBT)末端的准直器是中国散裂中子源(CSNS)工程中的关键部件之一,因其靠近靶站,辐射剂量大,维护困难,故设计可靠性极为重要。根据准直器的工作原理,及CSNS物理设计要求,对比国外同类加速器的设计经验,设计完成准直器设备。在设计过程中兼顾了热沉积、功率损耗和材料性能等方面的严格要求,并逐一阐述了具体方案。利用Bethe-Bloch公式计算与SRIM软件模拟的结果比较,确定了模拟工具和模拟方法的可靠性,根据ANSYS有限元软件模拟的结果,验证了准直器结构设计的可靠性。     

北京自由电子激光注入器输运线的设计与研制

注入器输运线由α磁铁、四极磁铁、真空盒和束测元件组成，对输运线中的物理问题诸如聚束、横向匹配、注入时间调整、准直误差等进行讨论。在介绍了各主要元件的性能之后，给出输运线设计参数和研制结果。     

基于单准直透镜的阵列准直器研究

提出了一种基于单准直透镜和光纤阵列的阵列准直器, 深入研究了此种方案的光路无胶和光路有胶的两种实现方式; 并基于高斯光束传输矩阵和q参数相关理论, 从理论上详细地计算、推导了各变量之间的关系, 并进行了模拟仿真及实验验证, 得到了理论和实验一致的结果. 对两种实现方式的结构及封装设计也进行了初步的摸索和实验, 并制作出了性能良好的阵列准直器. 理论和实验表明, 该方案具有易加工、低成本、易封装、性能优等特点, 也易于扩展成多维阵列准直器, 可为可重构光分插复用器系统和光交叉连接系统的发展提供强有力的器件支撑.     

中国散裂中子源快循环同步加速器主剥离膜设计

设计了中国散裂中子源(CSNS)快循环同步加速器(RCS)注入区的主剥离膜装置。为降低研制难度和成本，提高运行可靠性，选择了回转体式的结构。根据在线可调性、高稳定性、高定位精度和超高真空等技术难点，给出了CSNS/RCS主剥离膜的具体结构方案和控制方案。利用ANSYS有限元分析软件和材料力学原理，对设备的核心部件不锈钢同步带进行了模拟计算和理论分析。     

HL-2M 装置真空系统调试运行

在装置初步建成阶段,有序地开展真空系统的调试内容梳理,制定合理的调试步骤和调试方案,有 利于装置各系统的功能确认和故障排除,高效地开展各系统协同运行,为 HL-2M 装置初始等离子体放电提供装 置辅助系统层面的放电条件准备。装置真空系统主要涉及超高真空抽气系统、器壁处理系统和送气加料系统等。 基于制定的联调目标,针对 HL-2M 装置真空相关系统开展了界面关系梳理、子系统调试方案制定、系统工程联 调步骤和方案的拟定等工作,通过联调完成了装置在真空获得、壁处理、加料等方面的条件准备,为初始放电提 供了基本保障。      

用于闪光照相的准直器设计及性能

为了实现高度准直同时较好地保留飞层界面信息,针对高能闪光照相实验中常用的准直技术,改进了设计方法,以法国实验客体(FTO)为例,利用蒙特卡罗程序对光子电子耦合输运过程进行数值模拟实验,验证了所提出的准直器的性能,对采用该准直器技术下的模拟照相结果进行了准直器光程扣除方法研究,结果表明:改进的准直器将客体芯部区域的散射照射量降低99.8%,接收平面处的客体信号动态范围降低99.7%,同时在图像中完整地保留了客体外界面信息;对准直器轴向分层照相的方法可以获得误差小于0.1的客体光程。     

Experiments and analysis of thin tungsten slice and W/Cu brazing for primary collimator scraper in CSNS/RCS

According to the requirements for the beam collimation system of the rapid cycling synchrotron(RCS)of China Spallation Neutron Source(CSNS),the main structure of a scraper of primary collimator is made by W/Cu brazing,in which the thickness of tungsten slice is 0.17 mm.In order to get the best mechanical properties,the brazing temperature is suggested to be controlled under the recrystallization temperature of tungsten,while the recrystallization temperature is affected directly by the thickness of tungsten.Because of little research and application on the brazing of thin tungsten slice of 0.17 mm and copper,tensile tests are done to get the mechanical properties of tungsten slices which experience different brazing temperatures.In keeping the inner relationships between the mechanical properties and temperature,another experiment is done by using SEM to scan the microstructures including the size and distribution of crystals.Finally we determine the recrystallization temperature of tungsten slice of 0.17 mm,and get the best parameters of W/Cu brazing for scrapers of primary collimator in CSNS/RCS.     

Beam collimation for CSNS/RCS

The current design of the CSNS/RCS beam collimation system consists of a two-stage betatron collimation and a single momentum collimator. This paper summarizes various aspects of collimator design, including collimation principle and layout, material choice and collimator mechanical structure, etc. At last,radiation and thermal analysis are carried out to illustrate the feasibility of the current beam collimation scheme.     

Beam collimation for CSNS/RCS

The current design of the CSNS/RCS beam collimation system consists of a two-stage betatron collimation and a single momentum collimator. This paper summarizes various aspects of collimator design, including collimation principle and layout, material choice and collimator mechanical structure, etc. At last, radiation and thermal analysis are carried out to illustrate the feasibility of the current beam collimation scheme.     

Simulation on buildup of electron cloud in a proton circular accelerator

Electron cloud interaction with high energy positive beams are believed responsible for various undesirable effects such as vacuum degradation, collective beam instability and even beam loss in high power proton circular accelerators. An important uncertainty in predicting electron cloud instability lies in the detailed processes of the generation and accumulation of the electron cloud. The simulation on the build-up of electron cloud is necessary to further studies on beam instability caused by electron clouds. The China Spallation Neutron Source(CSNS) is an intense proton accelerator facility now being built, whose accelerator complex includes two main parts: an H-linac and a rapid cycling synchrotron(RCS). The RCS accumulates the 80 Me V proton beam and accelerates it to 1.6 Ge V with a repetition rate of 25 Hz. During beam injection with lower energy, the emerging electron cloud may cause serious instability and beam loss on the vacuum pipe. A simulation code has been developed to simulate the build-up,distribution and density of electron cloud in CSNS/RCS.     

Study on space charge effects of the CSNS/RCS

The Rapid Cycling Synchrotron (RCS) is a key component of the China Spallation Neutron Source (CSNS). The space charge effect is one of the most important issues in the CSNS/RCS, which limits the maximum beam intensity, as well as the maximum beam power. Space charge effects are the main source of emittance growth and beam loss in the RCS. Space charge effects have been studied by simulation for the CSNS/RCS. By optimizing the painting orbit, the optimized painting distribution was obtained. The space charge effects during the acceleration are studied and dangerous resonances, which may induce emittance growth and beam loss, are investigated. The results are an important reference for the design and commissioning of the CSNS/RCS.     

Study of eddy current power loss in an RCS vacuum chamber

In a Rapid Cycling Synchrotron (RCS), power loss due to an eddy current on the metal vacuum chamber would cause heating of the vacuum chamber. It is important to study the effect for estimating eddy current induced power loss and temperature growth. Analytical formulas for eddy current power loss for various types of vacuum chambers are derived for dipole and quadrupole repectively. By using the prototype of dipole of CSNS/RCS, an experiment was done to test the analytical formula. The derived formulas were applied to calculating the eddy current power loss on some special structures of an RCS vacuum chamber.     

A prototype RF power source for CSNS/RCS

A prototype RF power source has been built to supply high RF power to a ferrite-loaded cavity, which is a part of R&D of the Rapid Cycling Synchrotron of China Spallation Neutron Source (CSNS/RCS). A direct fast RF feedback amplifier, a 4:1 impedance transformer and auto tuning grid were locally located to compensate the heavy beam loading of CSNS/RCS. Design and commissioning of the RF power source is discussed here, also with some advice on system improvement.     

快循环同步加速器射频加速电压幅度的数字化控制

 中国散裂中子源(CSNS)快循环同步加速器（RCS）中的射频低电平控制系统是基于FPGA的全数字控制系统,旨在完成对射频频率、加速电压和同步加速相位的控制。介绍了CSNS/RCS射频系统的低电平数字化控制设计方案,并着重对射频加速电压幅度控制回路进行了分析与讨论。电压幅度控制环路通过射频电压幅度信号与电压幅度设定值的比较,得到误差信号。误差信号经过控制器来控制输入到射频腔的功率,以达到稳定和改变腔压的目的。通过对控制对象的分析和建模,得到了满足系统要求的控制器。详细介绍了数字系统的实现,尤其是信号的解调和控制算法的实现。用ALTERA公司的DSP builder进行数字控制系统开发,系统仿真结果表明,环路误差信号大约于10 μs（400个系统时钟）后归于0,整个电压幅度控制环路能稳定运行。