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 cryomodules. 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.     

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

A superconducting squeezed type half-wave resonator （HWR） of β=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.     

ADS超导直线加速器的准直方法北大核心

现代加速器科学实验装置的搭建是一项系统而繁杂的工作,其中应用到多种学科的专业技术。主要介绍了中国科学院近代物理研究所ADS直线加速器工程项目中的加速器标定准直安装的一般流程和方法,包括加速器控制网的建立、加速器元件的标定、加速器元件支架位置的放样和加速器元件的准直等。该项工作使用的仪器包括激光跟踪仪、关节测量臂,从理论角度讲解了加速器控制网的布设规则,标定测量坐标系的建立方法,准直工作数据处理的意义和计算方法,以及该系统工作所最终取得的成就。     

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.     

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强流质子直线加速器调谐系统测试分析

调谐系统是C-ADS超导直线加速器不可或缺的一部分, 在加速器运行过程决定了超导腔的运行频率, 直接影响了粒子加速的效果。为了充分了解调谐系统的工作情况和分析调谐系统出现的问题, 设计了实验对调谐系统进行全方位测试。首先对调谐器的杠杆机构和剪叉机构进行了力学分析, 而后对半波长谐振(HWR) 超导腔在不同状态下进行了电场模拟, 得出设计的调谐力和调谐位移满足HWR腔频率调谐要求。最后通过详细实验, 采用自动、手动等方式测试了恒温器CM1, CM2, CM3中超导腔调谐器工作时的线性度、回程差、直线单元部分的线性度及回程。结果显示: CM1的调谐器基本满足慢调谐需要, CM2存在1200步回程, 主要原因在于直线单元部分; CM3中调谐器的回程差较大, 线性度不高, 需要进一步改进。     

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.     

Electromagnetic characteristics of the CH cavity

In this paper, we present the RF simulation, the fabrication and the normal RF test of a six-cell copper model cross bar H mode (CH) cavity. The CH cavity was researched and developed at the Institute of Modern Physics for Injector II of the superconducting linac of the accelerator driven system of China, operating at a frequency 162.5 MHz, β=0.065. The deep drawing and electron beam welding were employed to fabricate this cavity, which would be used to develop the superconducting CH cavity in the future. The results of the normal RF test agree with the simulation of the electromagnetic properties, such as the electric field distribution on the cavity axis, frequency and Q factor.