兰州重离子冷却储存环二极磁铁设计

介绍了兰州重离子冷却储存环主环(CSRm)的改进W型二极磁铁和实验环(CSRe)C型二极磁铁的磁场计算和物理设计,在降低了磁铁造价和运行费用的前提下设计参数达到或超过了物理要求.根据样机的加工和检测结果来看,所有的磁场计算和物理设计的结果是可靠的.Magnetic field calculation and design of CSRm modified W-type dipoles and of CSRe C-type dipoles are presented in this paper. Under the condition of lower cost, all of the designed parameters are better than required values. Now the prototype has been fabricated and also the magnetic field measurement has been done. According to the measured results, all the calculation and design are very reliable.     

Full period superconducting section physics design for injector Ⅱ of China-ADS

The China Accelerator Driven Subcritical System （China-ADS） project, which is a strategic plan and aims to design and build an ADS demonstration facility, has been proposed and launched actively in China. Injector Ⅱ as one of the parallel injectors of China-ADS, and is prompted by the Institute of Modern Physics （IMP）. In this paper, a new scheme with full period lattice structure for the SC section is proposed. In the new scheme, there are sixteen periods, with one superconducting solenoid and one superconducting cavity included in each period. All of the elements are contained in four eryomodules. The dreadful influence of the mismatch caused by period structural change can be avoided, and the beam quality is favorable. In addition, this new scheme has certain advantages in reducing the project＇s difficulty and construction risk. The details of the design and beam dynamic simulation for the full period lattice structure are given in this paper.     

C-ADS超导轮辐腔Spoke021的电磁设计与优化

为满足C-ADS项目建设对超导轮辐腔Spoke021的需求,对Spoke021进行了详细的电磁参数优化。对Spoke021的参数化模型进行参数扫描,针对腔体的关键电磁特征量寻找可能存在的极值,详细分析、解释了优化过程中各个参数发生变化的物理意义。在Spoke021各参数达到最终优化值时,表征腔体性能的两个关键比值分别为:E_p/E_(acc)=3.14,Bp/E_(aCC)=4.77 mT/(MV/m)。考虑到次级电子倍增(Multipacting,MP)对Spoke021运行中所能达到的性能指标有很重要影响,对腔体的MP进行了建模分析。结果表明,当Spoke021工作在E_(acc)=10 MV/m情况下,没有发生MP,优化得到的参数可以满足Spoke021工程设计的需要;最后计算了腔体的TTF曲线,表明该腔体具有较宽的速度接受度。     

Commissioning of electron cooling in CSRe

The 400 MeV/u 12C6＋ ion beam was successfully cooled by the intensive electron beam near 1 A in CSRe.The momentum cooling time was estimated near 15 s.The cooling force was measured in the cases of difierent electron beam profiles,and the difierent angles between the ion beam and electron beam.The lifetime of the ion beam in CSRe was over 80 h.The dispersion in the cooling section was confirmed as positive close to zero.The beam sizes before cooling and after cooling were measured by the moving screen.The beam diameter after cooling was about 1 mm.The bunch length was measured with the help of the signals from the beam position monitor.The difiusion was studied in the absence of the electron beam.     

冷却储存环主环注入线二极磁铁测量

 介绍了兰州重离子加速器冷却储存环工程主环注入线二极磁铁的测磁系统和测磁结果。着重分析了垫补线圈和极头削斜两种手段对C型弯曲二极磁铁积分磁场径向分布均匀度的调节效果。并且分析了TOSCA三维磁场计算程序与实际测量结果之间的误差及其产生的原因。     

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。     

Design study of the SSC-LINAC re-buncher

A re-buncher with spiral arms for a heavy ion linear accelerator named as SSC-LINAC at HIRFL (the heavy ion research facility of Lanzhou) has been constructed. The re-buncher, which is used for beam longitudinal modulation and matching between the RFQ and DTL, is designed to be operated in continuous wave (CW) mode at the Medium-Energy Beam-Transport (MEBT) line to maintain the beam intensity and quality. Because of the longitudinal space limitation, the re-buncher has to be very compact and will be built with four gaps. We determined the key parameters of the re-buncher cavity from the simulations using Microwave Studio software, such as the resonant frequency, the quality factor Q and the shunt impedance. The detailed design of a 53.667 MHz spiral cavity and measurement results of its prototype will be presented.     

End-to-end simulation of the C-ADS Injector Ⅱ with a 3-D field map

The InjectorⅡ, one of the two parallel injectors of the high-current superconducting proton driver linac for the China Accelerator-Driven System (C-ADS) project, is being designed and constructed by the Institute of Modern Physics. At present, the design work for the injector is almost finished. End-to-end simulation has been carried out using the TRACK multiparticle simulation code to check the match between each acceleration section and the performance of the injector as a whole. Moreover, multiparticle simulations with all kinds of errors and misalignments have been performed to define the requirements of each device. The simulation results indicate that the lattice design is robust. In this paper, the results of end-to-end simulation and error simulation with a 3-D field map are presented.     

Beam dynamics study of RFQ for CADS with a 3D space-charge-effect

The ADS (accelerator driven subcritical system) project was proposed by the Chinese Academy of Sciences. The initial proton beams delivered from an electron cyclotron resonance ion source can be effectively accelerated by 162.5 MHz 4.2 m long room temperature radio-frequency-quadrupoles (RFQ) operating in CW mode. To test the feasibility of this physical design, a new Fortran code for RFQ beam dynamics study, which is space charge dominated, was developed. This program is based on Particle-In-Cell (PIC) technique in the time domain. Using the RFQ structure designed for the CADS project, the beam dynamics behavior is performed. The well-known simulation code TRACK is used for benchmarks. The results given by these two codes show good agreements. Numerical techniques as well as the results of beam dynamics studies are presented in this paper.     

Mechanical design and analysis of a low beta squeezed half-wave resonator

A superconducting squeezed type half-wave resonator(HWR)ofβ=0.09 has been developed at the Institute of Modern Physics,Lanzhou.In this paper,a basic design is presented for the stiffening structure for the detuning effect caused by helium pressure and Lorentz force.The mechanical modal analysis has been investigated the with finite element method(FEM).Based on these considerations,a new stiffening structure is proposed for the HWR cavity.The computation results concerning the frequency shift show that the low beta HWR cavity with new stiffening structure has low frequency sensitivity coefficient df/dp and Lorentz force detuning coefficient KL,and stable mechanical properties.