宽能谱激光驱动质子束的传输与均匀化  

Transmission and homogenization of laser-driven proton beams with broadband spectra

作　　者：朱军高 卢海洋 赵媛 赖美福 古永力 徐世祥[2] 周沧涛 Jungao Zhu;Haiyang Lu;Yuan Zhao;Meifu Lai;Yongli Gu;Shixiang Xu;Cangtao Zhou(Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology,Center for Advanced Material Diagnostic Technology,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,深圳市微纳光子信息技术重点实验室,教育部/广东省共建光电子器件和系统重点实验室,深圳518060

出　　处：《科学通报》2022年第34期4092-4100,共9页Chinese Science Bulletin

基　　金：深圳市基础研究资助项目(SZWD2021007,JCYJ20200109105606426);国家自然科学基金(92050203);中国工程物理研究院等离子体物理重点实验室资助。

摘　　要：激光加速器在几十年的发展中不断进步.激光等离子体作用产生的加速电场能够在微米尺度将质子加速到数十甚至百兆电子伏能量,有望成为新一代广泛应用的紧凑加速器.激光驱动质子束具有微米量级尺寸(点源)、安培量级的峰值电流、大能散、大散角等特点,具有广阔的应用前景.辐照应用要求质子束在较大面积上具有均匀分布剂量,因而需要在传输中完成从点源到较大面积、剂量均匀的质子束变换.为提高激光加速质子束的利用效率,要求传输的质子束能散范围尽可能大.而色差效应对大能散质子束的传输和均匀化提出了挑战.常梯度磁场的弱聚焦作用可以在水平和竖直方向同时聚焦,在水平方向分析能量;聚焦和能量分析一体化的光学特点能够实现消色差,或者显著降低色差的影响.本文研究了弱聚焦磁场用于大能散质子束传输和均匀化的特点和可行性,实现了20%能散质子束的均匀化传输.通过加入特殊的导向磁铁修正散角,减小色差效应在位置消色差中的影响,使得80%能散质子束传输后可保持较好的均匀性.对比质子束在强聚焦元件四极透镜中的传输,展示了弱聚焦磁场用于大能散质子束均匀化的优势.Over the past few decades, laser accelerators made continuous progress. Thanks to the ultra-high electric field gradient(100 GV/m) generated by the interaction of laser and plasma, protons can be accelerated to MeVenergy at a micron scale,being expected to be a new generation of widely used compact accelerators. The laser-driven proton beam has the characteristics of μm-level size(point source), ampere-level peak current, broadband energy spectrum, and large divergence angle. Irradiation applications need a uniform dose distribution, requiring the transformation from a point source to a large area of uniformly distributed particles. Increase of utilization efficiency requires that beams with energy spread as large as possible can be transmitted, while the chromatic aberrations pose a challenge to the homogenization of the beams, including the homogenization of the beams with the same energy and different initial divergence angles, and the homogenization of the beams with different energies.The weak focusing of the constant gradient magnetic field can focus in the horizontal and vertical directions at the same time, and analyze the energy in the horizontal direction. The integration of focusing and energy analysis can achieve achromatic transmission, or significantly reduce the influence of chromatic aberrations.This paper studies the transmission characteristics of proton beams in weak-focusing magnetic fields. The homogenized transformation for protons with the same energy in the horizontal direction from a point to a large area by point-to-parallel imaging is demonstrated. Point-to-parallel imaging is not a necessary condition for homogenization;transformation without point-to-parallel imaging in the vertical direction also obtains good homogeneity. The conditions for positional achromaticity in the horizontal direction are explored, and the transmission and homogenization of proton beams with 20%energy spread can be achieved with appropriate design.In positional achromatic transmission, the chromatic aberrati

关 键 词：激光加速 粒子束传输 粒子束应用 束流均匀化 弱聚焦磁场 

分 类 号：TL50[核科学技术—核技术及应用]