Electron cloud in accelerators
Electron cloud in accelerators
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DOI：
10.1142/s0217751x14300233
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发表时间：
2014-07-10
影响因子：
1.6
通讯作者：
Demma, Theo
中科院分区：
文献类型：
--
作者：
Cimino, Roberto;Demma, Theo
已知加速器中的低能电子与循环束相互作用，导致形成所谓的e（-）云。这种e（-）云可能对加速束流质量和稳定性产生不利影响。这些效应在大多数带正电粒子的加速器中都观察到了。长期以来，人们一直致力于详细了解这种e（-）云的物理起源，它的建立及其与循环束的相互作用。本文首先描述了加速器中电子云形成的起源和基本特征，然后回顾了模拟和分析这种现象的一些理论工作。在选定的情况下，将比较理论预期和实验观察，以解决基准代码与观察的重要性，以达到所需的预测能力。在这个范围内，代码需要真实的输入参数，这些参数可以正确地描述材料和表面特性，这些特性是基于e（-）云的形成和积累。实验工作，在世界各地的许多表面和材料科学实验室进行，以测量这些基本参数，然后将提出和严格审查。最后，我们将描述到目前为止所采用的一些e（-）云缓解策略，并得出一些结论。
Low energy electrons in accelerators are known to interact with the circulating beam, giving rise to the formation of a so-called e(-) cloud. Such e(-) cloud may induce detrimental effects on the accelerated beam quality and stability. Those effects have been observed in most accelerators of positively charged particles. A longstanding effort has been so far devoted to understand in detail the physical origin of such e(-) cloud, its build-up and its interaction with the circulating beam. We will first describe the origin and the basic features causing e cloud formation in accelerators, then we review some of the theoretical work produced to simulate and analyze such phenomenon. In selected cases, theoretical expectations and experimental observations will be compared, to address the importance of benchmarking codes versus observations to reach the required predictive capability. To this scope, codes need realistic input parameters which correctly describe material and surface properties at the basis of such e(-) cloud formation and build-up. The experimental efforts, performed worldwide in many surface and material science laboratories, to measure such essential parameters will then be presented and critically reviewed. Finally, we will describe some of the e(-) cloud mitigation strategies adopted so far and draw some conclusions.