面向激光驱动质子束应用的弱聚焦磁场束线设计研究  

Beamline design with weak-focusing magnetic field for applications of laser-driven proton beams

作　　者：朱军高 卢海洋 赵媛 赖美福 古永力 徐世祥[2] 周沧涛 Zhu Jun-Gao;Lu Hai-Yang;Zhao Yuan;Lai Mei-Fu;Gu Yong-Li;Xu Shi-Xiang;Zhou Cang-Tao(Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology,Center for Advanced Material Diagnostic Technology,and College of Engineering Physics,Shenzhen Technology University,Shenzhen 518118,China;Shenzhen Key Lab of Micro-Nano Photonic Information Technology,Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province,College of Physics and Optoelectronic Engineering,Shenzhen University,Shenzhen 518060,China)

机构地区：[1]深圳技术大学工程物理学院,先进材料测试技术研究中心,深圳市超强激光与先进材料技术重点实验室,深圳518118 [2]深圳大学物理与光电工程学院,教育部/广东省共建光电子器件和系统重点实验室,深圳市微纳光子信息技术重点实验室,深圳518060

出　　处：《物理学报》2022年第19期115-127,共13页Acta Physica Sinica

基　　金：深圳市基础研究资助项目(批准号:SZWD2021007,JCYJ20200109105606426);国家自然科学基金(批准号:92050203);等离子体物理重点实验室资助的课题。

摘　　要：随着高功率激光技术的进步,激光等离子体加速因其优异的加速结构获得迅速发展,现已获得近百MeV质子以及数GeV电子输出.激光驱动质子束具有μm量级尺寸、ps量级脉冲长度的优异品质.由于强激光场的存在,原位直接应用存在一定困难,因而更多应用场景需要通过束线把质子束传输到应用端.激光加速离子束由于具有宽能谱和大散角的特点,通过束线传输具有一定困难.常梯度磁场中的弱聚焦作用具有特别的优势:在水平和竖直方向可同时聚焦,在水平方向可进行能量分析,在水平和竖直方向的聚焦力可以通过磁场降落指数n进行分配,色差效应影响较小.通过对质子束在弱聚焦磁场中运动的束流动力学的研究,探索了弱聚焦作用在大能散、大散角质子束聚焦和能量分析中的要求、特点和优势.在合适的束流光学设计中,可以实现聚焦、选能的同时,压缩脉冲长度,有效缩减束线尺寸,优势显著.With the development of high-power laser technology,laser plasma acceleration has developed rapidly due to its excellent acceleration structure.Nearly one-hundred-MeV proton beams and several GeV electron outputs are obtained.The laser-driven proton beams have excellent quality of μm-scale sizes and ps-scale pulse lengths.Owing to the existence of the accelerating laser field,direct application is difficult,so the proton beams need to be transmitted to the application terminal through the beamline.However,the wide energy spectrum and large divergence angle bring difficulties in transmitting the beam.The weak focusing in the constant gradient magnetic field is neglected in the transmission of laser-driven particle beams because of the relatively weak focusing force.But weak focusing has special advantages:simultaneous focusing in the horizontal direction and the vertical direction,energy analysis in the horizontal direction,focusing force in the horizontal and vertical direction distributed by the field index n,and smaller influence of chromatic aberration effect.In this paper,we propose the beam transmission with weak-focusing magnet.The requirements for the focusing of proton beams with the same energy and different divergence angles in the X direction and Y direction in the weak-focusing magnetic field are explored by studying the linear beam dynamics of the beams.Then the conditions of precise energy analysis for particle beams with large divergence angle can be determined.For beams with 2% energy spread,the lengths of the drift space before and after the weak-focusing magnet and deflection radius are scanned to find out the minimum beam size and the shortest pulse length after transmission.It is found that a certain combination of drift space and deflection radius can minimize the beam size or the pulse length.Focusing and energy selection can be achieved while compressing the pulse length and effectively reducing the size of the beamline,which has significant advantages.When the deflection radius is0.65 m,t

关 键 词：激光加速 粒子束传输 粒子束应用 超快 

分 类 号：TL50[核科学技术—核技术及应用] TN249[电子电信—物理电子学]