北京散裂中子源RCS注入系统物理设计和研究(英文)

Physics Design and Study of the BSNS RCS Injection System

北京散裂中子源(BSNS)的主加速器——快循环同步加速器(RCS)采用H^-剥离注入方法,将从直线加速器预加速的束流进行累积和进一步加速．束流损失率的控制是该类高功率质子加速器所面临的关键问题之一,而束流损失中很重要的部分是由空间电荷效应造成的．为了减小该类束流损失,注入系统设计中利用H^-剥离注入和相空间涂抹方法将直线加速器预加速的发射度较小的束流尽可能均匀地涂抹到较大的横向相空间中．与其他的类似加速器相比,RCS注入系统将所有注入元件放在一个长为9m的无色散漂移节中以充分节省RCS环的纵向空间,并使对注入系统的操作与对RCS主体的操作完全独立．对于RCS累积的粒子数1．9×10^(13),空间电荷效应对粒子的运动有非常重要的作用,本文介绍了采用ORBIT程序进行三维模拟计算并进行设计优化的结果．还介绍了系统设计时需要考虑的其他重要因素,如质子穿越、电子收集等．

With the Beijing Spallation Neutron Source （BSNS） accelerator in design, intense H- beams are first accelerated by the linac and then injected in the rapid cycling synchrotron （RCS） for accumulation and further acceleration. The injection system uses H^- stripping and phase space painting method to fill the large ring acceptance with the linac beam of small emittance. The method is crucial to maintain low beam loss rate during the accumulation and initial acceleration. Different from the injection design of similar high-intensity accelerators in the world, the BSNS ring injection is accomplished by magnetic elements that are completely contained in a 9 meter-long uninterrupted space of near-zero dispersion. With the accumulated 1.9×10^13 particles, space charge effects play a very important role. The 3D simulations including space charge effects have been carried out to optimize the injection design. This paper presents the physics design, computer simulation results and design optimization of the injection system.