RFQ加速器同时加速同荷质比正负离子的实验研究

阐述了利用北京大学26MHz 300keV整体分离环高频四极场(ISR RFQ)加速器同时加速同荷质比正负离子的研究结果.分别用O⁺和O^－离子的连续束以及脉冲束同时注入,均实现了RFQ加速器对同荷质比正负离子的同时加速.用快靶测得的经RFQ腔同时加速后形成的O⁺及O^－离子微脉冲束与预想的正负氧离子微脉冲束相位关系完全一致.证实了同时加速时得到的氧离子束总和明显高于单加速一种离子时得到的氧离子束.在国际上首次实现了用RFQ加速器同时加速同荷质比的正负离子.     

Studies on RFQ accelerators and its applications

Development activities of Radio Frequency Quadrupole （RFQ） accelerators in China are presented. A 1 MeV O＋ RFQ and a 3.5 MeV ADS proton RFQ have been constructed. A novel separated function RFQ is under beam test, a 2 MeV D＋ RFQ is under construction and a CSNS RFQ is going to be constructed. The RFQ dynamics and the simultaneous dual beam acceleration with positive and negative ions were investigated and related codes were developed. The applications of RFQ will be further promoted in China.     

Power test of the separated function RFQ accelerator

The progress of the Separated Function RFQ (SFRFQ) accelerator, which can raise the field gradient of acceleration while maintaining the transverse focusing power sufficient for high current beam, is presented. In order to demonstrate the feasibilities of the novel accelerator, a prototype cavity was designed and constructed. Correspondingly, a code SFRFQCODEV1.0 was developed specially for cavity design and beam dynamics simulation. The prototype cavity will be verified as a post-accelerator for ISR RFQ-1000 (Integral Split Ring RFQ) and     

基于小型加速器的编码中子源成像研究

编码中子源成像可以在对中子注量率影响不大的情况下大大提高成像的准直比, 从而提高成像质量.北京大学开展了基于小型加速器的编码中子源成像技术研究工作. 不同于已有的基于反应堆的小面积编码板的研究工作, 北京大学建立了基于小型加速器的大面积编码板的编码中子源成像实验平台, 并对加速器中子源上的实验方法和数据处理进行了探索, 对比了重建算法, 获得了初步的重建照片.研究工作表明, 编码中子源成像技术可用于加速器中子源, 但重建图像质量仍须提高. 关键词： 加速器中子源 中子成像 编码源成像 图像重建     

分离作用RFQ加速系统研究进展

介绍了SFRFQ加速系统的最新研究进展.为验证SFRFQ结构的抗打火性能,设计了一个高功率模型腔,进行了高功率打火实验,并最终证明了该结构的可行性.为验证SFRFQ加速器的载束性能,设计了一台长度仅为lm的600keV O+SFRFQ加速器,它将把从1MeV ISR RFQ引出的O+离子加速到1.6MeV.为解决1MeV ISR RFQ引出柬流与SFRFQ加速器的横向匹配问题,在其间插入了一个三单元磁四极透镜.SFRFQ加速器加工和1MeV ISR RFQ改造的进展顺利.     

重离子整体分离RFQ加速器的升级改造

介绍了北京大学重离子整体分离环RFQ(ISR RFQ)加速器的升级改造工作,包括升级后RFQ加速系统的组成;强流永磁2.45GHz O+ECR离子源的台面测试结果;真空系统的改造;1MeV ISR RFQ加速器的高频控制系统改造;以及强流束流加速实验的结果.     

200MHz质子带窗四翼型射频四极场加速器结构模拟研究

根据束流动力学设计方案,使用电磁场计算软件CST Microwave Studio对带窗四翼型射频四极场(RFQ)结构进行了模拟研究,分析了加速腔结构参数对其物理特性的影响,得到了200MHz质子带窗四翼型RFQ优化结构方案。该结构的比分路阻抗为79.5kΩ·m,模式间隔达25.802MHz。与传统的四翼型RFQ比较结果表明:带窗四翼型RFQ具有较低的工作频率范围、良好的电稳定性以及较高的比分路阻抗。     

A Particle-in-cell scheme of the RFQ in the SSC-Linac

A 52 MHz Radio Frequency Quadrupole （RFQ） linear accelerator （linac） is designed to serve as an initial structure for the SSC-Linac system （injector into Separated Sector Cyclotron）.The designed injection and output energy are 3.5 keV/u and 143 keV/u,respectively.The beam dynamics in this RFQ have been studied using a three-dimensional Particle-In-Cell （PIC） code BEAMPATH.Simulation results show that this RFQ structure is characterized by stable values of beam transmission effciency （at least 95%） for both zerocurrent mode and the space charge dominated regime.The beam accelerated in the RFQ has good quality in both transverse and longitudinal directions,and could easily be accepted by Drift Tube Linac （DTL）.The effect of the vane error and that of the space charge on the beam parameters have been studied as well to define the engineering tolerance for RFQ vane machining and alignment.     

Power test of the separated function RFQ accelerator

The progress of the Separated Function RFQ (SFRFQ) accelerator, which can raise the field gradient of acceleration while maintaining the transverse focusing power sufficient for high current beam, is presented. In order to demonstrate the feasibilities of the novel accelerator, a prototype cavity was designed and constructed. Correspondingly, a code SFRFQCODEV1.0 was developed specially for cavity design and beam dynamics simulation. The prototype cavity will be verified as a post-accelerator for ISR RFQ-1000 (Integral Split Ring RFQ) and accelerate O+ from 1 MeV to 1.6 MeV. To inject a higher current oxygen beam for the prototype cavity, the beam current of ISR RFQ-1000 was upgraded to 2 mA. The status of high power and beam test preparation for the prototype cavity are presented in this paper.