Influence of the solenoid magnetic field on the self-modulation mechanism
Influence of the solenoid magnetic field on the self-modulation mechanism
复制标题
螺线管磁场对自调制机制的影响
DOI：
10.1017/s0263034620000178
复制
发表时间：
2020-06-01
影响因子：
0.9
通讯作者：
He, Yuan
中科院分区：
文献类型：
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作者：
Zhao, Xiao-ying;Yang, Yang-yang;He, Yuan
为保证中国加速器驱动系统（CIADS）束团的长距离传输，提出了在无窗靶前的加速器-靶耦合段施加外加磁场以减小自调制机制的新方案。利用粒子模拟方法研究了螺线管磁场对长质子束团在背景等离子体中运动时的自调制机制的影响。模拟中使用的长质子束团与CIADS直线加速器中的长质子束团相似。研究发现，螺线管磁场的存在将显著抑制自调制过程。在强磁场作用下，长束团的纵向分离和横向聚焦消失。我们将这些现象归因于强螺线管磁场限制了等离子体电子的横向运动。因此，聚束周围没有足够的电子来补偿空间电荷效应。此外，在没有横向电流的情况下，纵向箍缩效应消失，长束团不能再被分离成小脉冲。
For the guarantee of the long-distance transport of the bunches of China Initiative Accelerator Driven System (CIADS), a new scheme is proposed that extra magnetic field is used in the accelerator-target coupling section before the windowless target to minimize the self-modulation (SM) mechanism. Particle-in-cell simulations are carried out to study the influence of the solenoidal magnetic field on the self-modulation mechanism when long proton bunches move in the background plasmas. The long proton bunches used in the simulations are similar to these in the linear accelerator of CIADS. It is found that the presence of the solenoidal magnetic field will significantly inhibit the self-modulation process. For the strong magnetic field, the longitudinal separation and transverse focusing of the long bunches disappear. We attribute these phenomena to the reason that the strong solenoidal magnetic field restricts the transverse movement of plasma electrons. Thus, there are not enough electrons around the bunch to compensate the space charge effect. Moreover, without transverse current, the longitudinal pinched effect disappears, and the long bunch can not be separated into small pulses anymore.