Adjusting the accelerating field distribution of a superconducting CH cavity

In a superconducting CH (cross bar H mode) cavity, the method of regulating the length of a drift tube is employed to adjust the distribution of the accelerating field. In this article, we simulate the electromagnetic field of a CH structure to illustrate the reason for adjusting the field distribution by varying drift tube length. Meanwhile, that the presence of the drift tube will cause a sharp rise in the maximum electric field is also shown. This phenomenon is contrary to superconducting cavity design principles in which the cavity geometry needs to be optimized to reduce the maximum electric field to avoid field emission. We propose a variable diameter superconducting CH cavity design to solve this conflict. The simulation of the variable diameter superconducting CH cavity shows that this method is feasible.     

兰州重离子加速器冷却储存环kicker磁铁设计

 介绍了兰州重离子加速器冷却储存环（HIRFL-CSR）CSRm引出kicker磁铁的物理设计、参数计算以及结构设计和加工。为了减小电感，使上升时间达到要求，CSRm引出kicker磁铁采用分布式的传输线方案，同时将无感电容与磁铁并联以满足匹配的问题。磁铁用单匝线圈和铁氧体铁芯来降低电感、减少涡流损耗，并采取两台电源成对供电、导体一端共地的结构形式消除杂散电感和轴向场，这种方式不但消除了过桥的不利影响，而且可通过调节导体间距离方便的调节磁场均匀区宽度和磁铁电感。完成设计后磁铁电感小于1 μH，在140 mm范围内磁场均匀度好于±0. 5%，最高磁场达到0.038 T，最大峰值激磁电流约为2.5 kA。     

Numerical optimization and multi-particle dynamics simulation of the radial matching section of the RFQ

The ABC code is an optimization program for the development of matching channels and dynamical matchers in radio frequency quadrupole (RFQ) structures, and a new approach to this code to define the geometry of the radial matching section of the RFQ has been developed. This approach is based on the application of the numerical optimization step by step. This optimization is intended to search for the initial matching condition of a beam, the optimization of parameters of a cell of the channel on given characteristic parameters and traces of a beam in linear channels in both forward and backward directions. To further verify the results of the optimization, multi-particle beam dynamics simulations have been carried out using the BEAMPATH and TRACK codes. The result of the beam dynamics simulation shows that the optimization result of the ABC code is reasonable and this approach provides an opportunity to redesign the structure of the radial matching section of the RFQ.     

Study on the frequency tuning of the half-wave resonator at IMP

The RF and mechanical coupled analyses are essential in superconducting cavity design in order to predict the deformation of the cavity walls and the frequency shift caused by the deformation. In this paper, the detuning caused by both bath helium pressure and Lorentz force is analysed and a tuning system has been investigated and designed to compensate the detuning by deforming the half-wave resonator along the beam axis. The simulations performed with ANSYS code show that the tuning system can adjust and compensate the frequency drift due to external vibrations and helium pressure fluctuation during operation.     

Development of a superconducting solenoid for CADS

A superconducting focusing solenoid has been designed and developed for the China Accelerator Driven System (CADS). In order to meet the requirement of focusing strength and fringe field while minimizing the physical size of the solenoid, the novel optimizing design method based on a linear programming method was employed. In this report, the design of the solenoid including magnetic field optimization, mechanical design and quench protection will be introduced. The solenoid has been fabricated and tested. The testing results show that the central field reached 8.4 T and the stray field was lower than 50 Gauss in the cavity zone.     

ADS注入器Ⅱ热冲击损伤研究(英文)

由于束流脉冲无法控制而引起直线加速器的热冲击损伤是造成加速器无法完成聚束及偏转的主要因素,而对热冲击进行定量的热应力评估可以有效地避免RFQ、超导腔以及其他加速元件等加速器设备的损伤,这在研制强流直线加速器的过程中至关重要。本研究引用一种新颖的计算方法定量分析整个注入器的热冲击损伤并明确了三种不同材料高纯铌、无氧铜和不锈钢对应的加速器件的热冲击的特征。基于有限元方法对瞬态热应力进行分析,得出三种不同材料对应的加速器件在入射角度为90度时的温度分析结果。对于所研制的注入能量低于10 MeV的强流直线加速器来讲,得到可允许的入射时间为20μs。     

CiADS固态功率源的可用性设计与分析

ADS加速器面临的一大技术挑战是高可用性要求,进行固态功率源可用性设计是为ADS加速器的可用性设计与分析做准备。首先对CiADS的可用性要求进行了分配,固态功率源的分配结果为0.999;然后对固态功率源进行了初步可用性设计,分析的结果无法满足要求;最后对固态功率源进行了冗余设计,使用Reliasoft软件建立了固态功率源的可靠性框图,分析结果显示:满足一定的维修条件下,当其他元件的平均故障间隔时间（MTBF）达到171 702 h,25/28冗余设计可以满足0.999的可用性要求。One of the challenging technologies of ADS is the high availability requirement. The availability design of the solid-state amplifier is the preparation for ADS. Firstly the availability requirement of CiADS is proposed as 0.8. The distribution result of the solid-state amplifier is 0.999 according to this requirement. Then the availability result shows the preliminary design of solid-state amplifiers can not reach the availability requirement. At last the power loss is considered to build the k/N redundancy model of the main amplifier and the mean time between failure (MTBF) is calculated for various redundancy models. The reliability block diagram of the solid-state amplifier is set up by Reliasoft and the simulation results show that the 25/28 redundancy model can meet the requirement 0.999 when MTBF of other components reaches 171 702 hours with the certain maintenance.     

CR超导二极磁铁线圈受力分析

采用有限元分析的方法, 以CR超导二极铁为研究对象, 对其进行受力分析, 分别计算线圈所受到的电磁力以及在此力作用下线圈发生的应变, 线圈和相邻部分降温速率不均匀引起的热应力的分布以及线圈发生的应变. 最后利用所得到的数据来校对线圈和线圈盒的强度, 为结构的优化设计提供依据, 并为失超保护提供可参考的数据.     

CR超导二极铁导线的3D有限元失超模拟

利用FEM软件ANSYS对德国GSI的FAIR项目的超导二极铁的超导线进行了失超模拟. 该模拟形象地给出导线的失超过程, 通过APDL编程可以得到失超传播速度, 失超时导体的端电压随时间的变化. 文章还进一步研究了导线的最小失超传播区域MPZ, 失超段初始温度和电流对失超传播速度的影响.     

CR环二极磁铁的磁场优化

FAIR项目中的CR环二极磁铁对磁场积分场的误差分布要求很高, 通过削斜与加载镜像板的方法是优化磁场的主要方法, 文中介绍了对二极磁铁优化方法和对它的处理方法. 利用削斜的方法来改变二极磁铁积分场的误差分布, 通过复杂的削斜, 已将其高场的误差分布优化到±2×10^－4. 加镜像板的方法主要适合高场, 而对低场的调节不明显. 另外处理方法的选取对结果的影响也很大, 文中对两种方法作了比较. 优化模拟计算软件采用的是专门的磁场计算工具OPERA.