Effect of quadrupole focusing-field fluctuation on the transverse stability of intense hadron beams in storage rings
Effect of quadrupole focusing-field fluctuation on the transverse stability of intense hadron beams in storage rings
复制标题
四极聚焦场涨落对存储环强强子束横向稳定性的影响
DOI：
10.1093/ptep/pty004
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
and H. Okamoto
中科院分区：
文献类型：
--
作者：
K. Ito;M. Matsuba;and H. Okamoto
本文系统地研究了噪声引起的束流不稳定性与参数的关系[M。Chung等人，102，145003（2009）]。由于驱动力较弱，不稳定性发展非常缓慢，这大大限制了传统的实验和数值方法的应用。本研究采用一种新型的桌面装置S-POD（粒子轨道动力学模拟器）来研究强流强子束的长期集体行为。S-POD提供了一个多体库仑系统物理等效的相对论带电粒子束，从而使我们能够进行各种束动力学实验，而不使用大型机器。它重新确认，随机噪声的线性束聚焦电位可以是一个缓慢的光束质量退化的来源。实验观察很好地解释了一个简单的微扰理论，预测存在一系列的危险的噪声频段被忽视在以前的研究。S-POD新识别的那些额外的不稳定带实际上更重要，因为驱动噪声频率可能非常低。的不稳定性的噪声水平，操作的调整，和光束强度的依赖关系进行检查，发现与理论预测一致。
A systematic experimental study is performed to clarify the parameter dependence of the noise-induced beam instability previously demonstrated by a Princeton group [M. Chung et al., Phys. Rev. Lett.102, 145003 (2009)]. Because of the weakness of the driving force, the instability develops very slowly, which substantially limits the application of conventional experimental and numerical techniques. In the present study, a novel tabletop apparatus called “S-POD” (Simulator of Particle Orbit Dynamics) is employed to explore the long-term collective behavior of intense hadron beams. S-POD provides a many-body Coulomb system physically equivalent to a relativistic charged-particle beam and thus enables us to conduct various beam-dynamics experiments without the use of large-scale machines. It is reconfirmed that random noise on the linear beam-focusing potential can be a source of slow beam quality degradation. Experimental observations are explained well by a simple perturbation theory that predicts the existence of a series of dangerous noise frequency bands overlooked in the previous study. Those additional instability bands newly identified with S-POD are more important practically because the driving noise frequencies can be very low. The dependence of the instability on the noise level, operating tune, and beam intensity is examined and found consistent with theoretical predictions.