强流低能加速器束流损失机理的Parallel PIC/MCC算法与实现

The beam emittance growth and the beam halo induced by the nonlinear space charge effect, and the aberration caused by the applied electromagnetic field are all the frontier research topics of the high-current and low-energy accelerators, which are the key factors for beam loss control and high beam power achieved. In order to ensure the safety operation and maintenance of the accelerator devices, the beam loss rate should be predicted at the high-current and low-energy accelerator design. Combining the advantages of Particle-In-Cell method and Monte-Carlo-Collision method, this project will use the Parallel PIC / MCC method to study the space charge effect , coulomb scattering between the identical particles, collision between the differential particles and so on during the beam transmission, which is used to realize the mechanism of beam loss in the high-current and low-energy proton linac. Then, the related measurement experiments are carried out on the HINEG to verify and optimize the simulation results. The above research will provide a good technical support for long-term operation of the accelerator-type fusion device, extension of the beam life and the service life. Meanwhile, the written numerical simulation code will be of great significance to the design research of any high-current and low-energy accelerator.

非线性空间电荷效应引起的束流发射度增长、束晕和外加电磁场引起的像差等是强流低能加速器的前沿研究课题，是束流损失控制和达到高束流功率的关键因素之一。为了保证加速器运行安全以及加速器设备的维护安全，离子束输运过程中的束流损失率需要在强流低能加速器设计之初就加以预测。结合Particle-In-Cell方法和Monte-Carlo-Collision方法的优点，本项目将采用并行PIC/MCC方法研究束流输运过程中的空间电荷效应、同类粒子之间的库仑散射以及非同类粒子之间的碰撞等物理过程，实现强流低能质子束输运过程中的束流损失机理研究；并在强流氘氚中子源实验装置HINEG上进行相关的测量实验，验证和优化模拟结果。上述研究将为加速器型聚变装置的长时间稳定运行、使用寿命和束流寿命的延长提供良好的技术支撑。同时，编写的数值计算模拟程序对任意强流低能加速器的设计研究具有重要意义。

目前世界上包括我国在内的很多国家正在发展小型化的加速器型氘氘/氘氚聚变中子源。该类型加速器中子源的束流能量较低，束流流强较大，非线性空间电荷效应引起的束流发射度增长、束晕和外加电磁场引起的像差等是强流低能加速器的前沿研究课题，是束流损失控制和达到高束流功率的关键因素之一。为了更好的服务于小型加速器中子源的产业化，本项目基于Parallel PIC/MCC方法对强流低能离子束输运过程中的确定性问题（强空间电荷效应）和随机问题（库伦碰撞）进行了研究，完善了相关理论模型，并对理论模型进行了实验验证，课题研究在非相对论束流的输运方面进行了创新，推动了低能加速器产业化的发展，并满足国内小型加速器产业化的实际需求。同时，编写的数值计算模拟程序对任意强流低能加速器的设计研究具有重要意义。