高能重离子同步加速器中，利用RF-KO获得高均匀度慢引出束的方法研究

The heavy ion beams, with the characteristics of high energy and high uniformity, are widely used in high energy nuclear physics, cell biology, material irradiation, space radiation simulating in the earth and other relevant research fields. These heavy ion beams are mainly realized by RF-knockout slow extraction method in the synchrotron. The uniformity of the spill, decided by the quadrupole power supply ripple and the mechanism of RF-knockout method, is unable to satisfy the requirements of the uniformity in some experiments. In this project, the study of how to improve the uniformity of the spill will be carried out in the facility of HIRFL-CSR. The dynamic simulation and the code development of the RF-knockout slow extraction in high energy synchrotron will be carried out. The uniformity of the spill, which influenced by the transverse RF frequency modulation and amplitude modulation as well as the different synchrotron parameters, such as the work point, chromaticity, will be studied. The CSRm slow extraction commissioning will be proposed to get the high energy and high uniformity spill, and verify the simulation results. The studies of getting high uniformity spill will not only provide a good experimental platform for heavy ion irradiation in HIRFL-CSR, but will also provide theory basis and design experience for the high energy accelerator facility construction in the future.

高能、高均匀度的重离子束广泛应用于高能核物理研究、细胞生物学研究、材料辐照研究、空间辐射地面模拟研究等学科领域。该重离子束主要依靠同步加速器的RF-knockout共振慢引出来实现。由于引出束流的均匀性受四极铁电源纹波、RF-knockout内在机理的影响，无法满足部分实验研究对束流均匀性的要求。本项目拟在现有加速器装置HIRFL-CSR上针对如何提高慢引出束流的均匀性进行研究。主要包括：1) 进行高能重离子RF-knockout慢引出的动力学模拟和程序开发；2) 研究不同横向RF频率和电压参数以及同步加速器的相关设置诸如工作点、色品等对束流均匀性的影响；3) 通过束流调试，验证模拟结果，并在CSRm上获得高能高均匀度慢引出束。进行高能高均匀度慢引出束研究，不仅能为HIRFL-CSR重离子辐照研究提供更好的实验平台，也可为将来高能重离子加速器的建设提供理论依据和设计经验。

利用该项目的支持，进行了RF-KO的细致研究：.1. 开发了慢引出的束流动力学模拟程序，利用该程序可模拟粒子在受到横向高频电场作用下的精确运动过程；.2. 利用该模拟程序，通过改变横向电场的相关参数，比如电压曲线、扫频频率、扫频方式等，得到了这些参数对引出束流均匀性的影响。同时改变加速器的相关参数，例如束流的工作点、色品等，得到了加速器的参数对慢引出束均匀性的影响；.3. 利用这些模拟结果，在CSRm（即兰州重离子同步加速器）以及HIMM-WW（即武威重离子治癌装置）上进行了试验，完美验证了模拟结果的准确性，并大大改善了两个加速器上慢引出束流的均匀性，为核物理实验、重离子治癌应用，以及将来建设大型强流重离子加速器打下了良好基础。