Simulations on the Fast-Ion Instability in the International Linear Collider Damping Rings
Simulations on the Fast-Ion Instability in the International Linear Collider Damping Rings
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DOI：
10.1143/jjap.48.086501
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发表时间：
2009-08
影响因子：
1.5
通讯作者：
Eun-San Kim;K. Ohmi
中科院分区：
文献类型：
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作者：
Eun-San Kim;K. Ohmi
被电子束捕获在环中的离子在束势中以一定的频率振荡。振荡，这是不相干的在早期阶段，成为相干的，并动摇了光束的频率。这就是离子不稳定性的机制。本文研究了国际直线对撞机（International Linear Collider）两个高强度低发射度阻尼环OCS 6和FODO 4中的快离子不稳定性，其中快离子不稳定性的增长速度可能非常快。我们已经进行了模拟的基础上的弱-强模型和分析估计调查的特征现象的快离子不稳定性，这是一个关键问题的阻尼环。我们研究了离子频率、束团填充模式、真空压力和反馈系统对阻尼环中快离子不稳定性的影响。在我们的模拟中，离子和束之间的相互作用是使用阻尼环的磁性组件进行的。模拟结果表明，约50匝的逐束团反馈足以抑制阻尼环中的快离子不稳定性。据估计，由于离子在束中的调谐偏移是小的。
Ions trapped by electron beams in the rings oscillate with a certain frequency in the beam potential. The oscillation, which is incoherent at the early stage, becomes coherent and shakes the beam with a frequency. This is the mechanism of the ion instability. We investigate the fast-ion instability in the two proposed International Linear Collider damping rings of OCS6 and FODO4 with a high intensity and a low-emittance in which the growth rate may be very rapid. We have performed a simulation based on the weak-strong model and analytical estimate to investigate characteristic phenomena of the fast-ion instability that is a critical issue in the damping rings. We investigated the effects of the ion frequencies, bunch filling patterns, vacuum pressures, and a feedback system on the fast-ion instabilities in the damping rings. The interactions between ions and beams in our simulations were performed using the magnetic components of the damping ring. The simulation results show that the bunch-by-bunch feedback of about 50 turns is sufficient to suppress the fast-ion instabilities in the damping ring. It is estimated that the tune shifts in the beam due to the ions are small.