【作者】 马鹏飞；

【导师】 王群书；

【作者基本信息】 清华大学 ， 核科学与技术， 2022， 博士

【摘要】 空间辐射环境中的质子和重离子引起的辐射效应会造成航天器故障,因此航天器的关键设备需要进行辐射效应测试,加速器产生的带电粒子可用于模拟空间辐射环境,同步加速器是空间辐射环境模拟装置中的主流加速器。直线注入器的注入束流的参数需要满足同步加速器需求,其中一个主要需求是水平发射度小。论文基于西安200 Me V质子应用装置（Xi PAF）重离子升级对注入器的需求,提出了加速离子荷质比大于1/6.5、注入能量2 Me V^/u、束流水平和垂直归一化发射度分别小于1.0和2.6^πmm^?mrad的设计目标。针对同步加速器对注入束流发射度的特定需求,论文从水平发射度小的扁平束团实现以及降低下游加速器的发射度增长两个方面,在保证注入束流流强的前提下实现较低的水平发射度。水平发射度的降低可明显提高同步加速器的注入增益,进而提高同步加速器储存的粒子数,对提高空间辐射模拟装置的粒子注量率,具有重要的应用前景和研究意义。论文提出一种重离子扁平束团实现方法,即利用电子回旋共振（ECR）离子源引出区的螺线管出口边缘场优化本征发射度、利用旋转四极磁铁进行保辛变换解耦合,可有效优化离子源引出束流的本征发射度,并获得水平发射度低的扁平束团。将束流归一化RMS发射度从0.10^πmm^?mrad优化至0.06^（）/0.20^（）πmm^?mrad,从而为提高同步加速器的注入增益和提高注入粒子数创造了必要条件。论文将交叉指型漂移管直线加速器（IH-DTL）加速结构与聚焦-散焦周期结构（FD lattice）相结合,提出了带有电磁四极磁铁聚焦的IH-DTL（IH-EMQ）束流动力学及其低发射度增长的优化设计方法。IH-EMQ动力学优化方法包括优化lattice结构和优化入口束流相空间参数,可明显抑制了IH-DTL中的发射度的增长。此外,论文提出并实现基于纵向网格模型的传输矩阵束流动力学计算方法,可进行快速地发射度计算和优化设计。基于发射度优化设计方法完成了一套重离子IH-DTL设计,可加速多种荷质比离子,归一化RMS发射度增长为7%,同时完成了射频四极（RFQ）加速器与IH-DTL之间的优化的束流匹配衔接。论文对整个注入器进行了优化设计和模拟,用¹⁹⁷Au³⁰⁺扁平束团进行整个注入器的模拟,束流在低能束流输运线（LEBT）出口实现了扁平束团,在下游加速器实现18%水平发射度增长。在注入点,束流归一化发射度（99%粒子）为0.53（）/1.18（）πmm^?mrad,整个注入器可以满足重离子同步加速器的注入需求。更多还原

【Abstract】 The radiation effect caused by protons and heavy-ions in the space radiation envi-ronment will result in spacecraft failure.Therefore,the key components of the spacecraft need to be tested for radiation effect.The charged particles produced by the accelerator can be used to simulate the space radiation environment.The synchrotron is the main-stream accelerator in space radiation simulation facilities.Parameters of the injection beam of the linac injector need to meet the requirements of the synchrotron,one of which is the low emittance in the horizontal direction.Based on the requirements of the heavy-ion injector of Xi’an 200 Me V proton appli-cation facility（Xi PAF）heavy-ion upgrading project,it is pointed out that the charge-mass ratio of the particles should be larger than 1/6.5,the injection energy should be larger than2 Me V^/u,the horizontal and vertical normalized emittances of the beam should be less than 1.0 and 2.6^πmm^?mrad,respectively.According to the specific requirements of the synchrotron for the emittance of the injection beam,the low horizontal emittance on the premise of ensuring the injection beam current can be realized from two aspects:the re-alization of the flat beam and the reduction of the emittance growth of downstream accel-erator.The decrease of horizontal emittance can significantly improve the injection gain of the synchrotron,thus increasing the stored particles in the synchrotron,and improv-ing the particle fluence rate of space radiation simulation facility,which has important application prospects and research significance.In the design,a method to realize the heavy-ion flat beam is proposed,that is:the eigen-emittances are optimized by using the exiting fringe field of the solenoid in the elec-tron cyclotron resonance（ECR）ion source extraction area,and the transverse symplec-tic decoupling transformation is carried out by rotating the quadrupole magnets,which can effectively optimize the eigen-emittances of the beam and obtain the flat beam with low horizontal emittance.The normalized RMS emittance of the beam is optimized from0.10^πmm^?mrad to 0.06^（）/0.20^（）πmm^?mrad in the thesis,which creates necessary con-ditions for improving the injection gain and the number of injected particles of the syn-chrotron.Combining the acceleration structure of the interdigital drift tube linac（IH-DTL）with focusing-defocusing periodic structure（FD lattice）,the IH-DTL with electromag-netic quadrupole focusing（IH-EMQ）beam dynamics and its optimal design method for low emittance growth are proposed.The optimization method of IH-EMQ beam dynam-ics includes optimizing the lattice structure and phase space parameters of the input beam.It can inhibit the increase of emittance in the IH-DTL.In addition,a calculation method named beam dynamics with transfer matrix based on longitudinal grid model is proposed and implemented,which can calculate and optimize the emittance quickly.Based on the emittance optimization design method,a heavy-ion IH-DTL is designed,it can accelerate particles with multiple charge-mass ratios and the normalized RMS emittance growth is7%.Also,the optimized beam matching section between the radio frequency quadrupole（RFQ）accelerator and the IH-DTL is completed.The whole injector is optimized and simulated with¹⁹⁷Au³⁰⁺flat beam.The flat beam is realized at the exit of the low energy beam transport line（LEBT）and the hor-izontal emittance growth is 18%in the downstream accelerator.At the injection point,the normalized emittance of the beam（99%particles）is^{0.53（）/1.18（）π}mm^?mrad.The whole injector can meet the injection requirements of the heavy-ion synchrotron.更多还原