Beam dynamics and RF design of trapezoidal IH-RFQ with low energy spread

Beam dynamics and RF design have been performed of a new type trapezoidal IH-RFQ operating at 104 MHz for acceleration of 14C+ in the framework of RFQ based 14C AMS facility at Peking University. Low energy spread RFQ beam dynamics design was approached by the method of internal discrete bunching. 14C+ will be accelerated from 40 keV to 500 keV with the length of about 1.1 m. The designed transmission efficiency is better than 95% and the energy spread is as low as 0.6%. Combining the beam dynamics design, a trapezoidal IH-RFQ structure was proposed, which can be cooled more easily and has better mechanical performance than traditional RFQ. Electromagnetic field distribution was simulated by using CST Microwave Studio (MWS). The specific shunt impedance and the quality factor were optimized primarily.     

分离作用RFQ加速器物理特性的研究

RFQ加速器中加速效率随加速能量的增高而下降,为克服由此导致的RFQ能量局限而提出的分离作用RFQ加速结构,在仍保持采用射频四极场聚焦的同时,将加速与聚焦作用相分离. 综述了对它的加速效率、反场问题、腔体及束流特性研究 的结果,初步证实了其可行性及在较高能量区加速效率得到提高,并对正在研制的一台采用了这种分离作用RFQ的1.5MeV组合加速器做了介绍.     

低能强流离子束输运实验台控制系统的研制

介绍了一种基于Siemens S7-300 PLC的计算机控制系统, 用于对北京大学重离子物理研究所低能强流离子束实验台设备的自动控制和束流监测. 该系统通过PROFIBUS-DP过程现场总线完成主站和从站的数据交换和分布控制, 上位机采用Siemens WinCC软件集中监控, 实现可视化过程控制、数据记录和保存、报警和自动保护、远程控制和数据通信等功能. 本文着重阐述在离子束输运装置对控制系统基本要求的基础上, 如何选择系统结构并确定系统方案, 以及对现有设备的自动化改造、软硬件的合理配置、可视化人机操作界面的设计.     

ECR氧离子源及整体分离环RFQ加速器低能输运系统的研制

根据研制分离作用RFQ和升级改造1MeV ISR RFQ的需要,设计了一台ECR O⁺离子源及低能输运(LEBT)系统. 低能输运系统使用2个静电透镜聚焦束流, 在引出电压22kV时, LEBT末端得到6mA以上总脉冲束流、束流归一化均方根发射度为0.12πmm﹒mrad. 束腰可前后移动160mm.     

Preliminary design of a laser accelerator beam line

A compact laser plasma accelerator(CLAPA) is being built at Peking University, which is based on an RPA-PSA mechanism or other acceleration mechanisms. The beam produced by this laser accelerator has the characteristics of short duration, high pulse current, large divergence angle, and wide energy spectrum. The beam cannot be produced by a normal ion source and accelerator. The space charge field in the initial is very strong.According to the beam parameters from preparatory experiments and theoretical simulations, a compact beam line is preliminarily designed. The beam line mainly consists of common transport elements to deliver proton beam with the energy of 1–50 MeV, energy spread of 0–±1% and current of 0–108 proton per pulse to satisfy the requirement of different experiments. The simulation result of a 15 MeV proton beam with an energy spread of ±1%, current of 400 m A, and final spot radius of 9 mm is presented in this paper.     

Experimental study of the plasma window

The plasma window is an advanced apparatus that can work as the interface between a vacuum and a high pressure region. It can be used in many applications that need atmosphere-vacuum interface, such as a gas target, electron beam welding, synchrotron radiation and a spallation neutron source. A test bench of the plasma window is constructed in Peking University. A series of experiments and the corresponding parameter measurements have been presented in this article. The experiment result indicates the feasibility of such a facility acting as an interface between a vacuum and a high pressure region.     

低能强流离子束输运实验台控制系统的研制

介绍了一种基于Siemens S7-300 PLC的计算机控制系统,用于对北京大学重离子物理研究所低能强流离子柬实验台设备的自动控制和束流监测.该系统通过PROFIBUS-DP过程现场总线完成主站和从站的数据交换和分布控制,上位机采用Siemens WinCC软件集中监控,实现可视化过程控制、数据记录和保存、报警和自动保护、远程控制和数据通信等功能.本文着重阐述在离子束输运装置对控制系统基本要求的基础上,如何选择系统结构并确定系统方案,以及对现有设备的自动化改造、软硬件的合理配置、可视化人机操作界面的设计.     

整体分离环RFQ加速器的研究

阐述了北京大学整体分离环高频四极场（ＩＳＲＲＦＱ）加速器研究所取得的研究成果．分别论述了２６ＭＨｚ３００ｋｅＶＩＳＲＲＦＱ加速器结构、束流动力学设计、高频控制系统、束流试验装置及束流试验；分析了其对Ｎ＋、Ｏ＋、Ｏ－束流试验的研究结果；简述了２６ＭＨｚ１ＭｅＶＲＦＱ加速器束流动力学、加速腔设计及目前的进展 The status of the ISR RFQ accelerators in Peking University is described. The structure of ISR RFQ accelerator, beam dynamics calculation results by PARMTEQ, RF systems, beam transport lines and the beam test evolutions of a 26 MHz 300 keV ISR RFQ accelerator are also presented, respectively. The beam test results for N +, O +, O - particles are analyzed in detail. At last, the development of 1 MeV 26 MHz ISR RFQ accelerator is introduced briefly.     

分离作用RFQ膜片电极的优化设计

用RELAX3D模拟分离作用射频四极场(SFRFQ)加速结构中傍轴下的电场分布，并分析了膜片孔径、加速间隙等参数对粒子能量增益的影响，找到了设计SFRFQ电极的一般方法，使得在极间电压为70kV的情况下(以O⁺为例)，粒子通过一个周期单元，可获得100keV以上的能量增益，小球微扰法的测量值与模拟结果能很好的符合. 关键词： 分离作用射频四极场 RELAX3D 能量增益 反场     

美国粒子束物理新进展

美国粒子束物理新进展高能粒子束物理不仅对人类认识自然和宇宙有着重要影响，而且对核反应堆废料的处理、核燃料的再生、惯性约束聚变、加速器驱动的洁净核能源系统等未来能源技术也将产生深远的影响．１９９６年美国在高能粒子束物理方面取得了具有里程碑意义的进展．１...