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arXiv 1407.0772physics.acc-phphysics.ins-det
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加速器环境中次级电子产额现场测量的仪器和方法报告

Report on Instrumentation and Methods for In-Situ Measurements of the Secondary Electron Yield in an Accelerator Environment

W. H. Hartung, D. M. Asner, J. V. Conway, C. A. Dennett, S. Greenwald, J. -S. Kim, Y. Li, T. P. Moore, V. Omanovic, M. A. Palmer, C. R. Strohman

摘要:

粒子加速器可实现的射束电流和射束质量可能受到真空室中电子云(EC)的积聚的限制。来自真空室壁的次级电子发射可有助于电子云的生长。为配合康奈尔电子储存环(CESR)试验加速器计划(CesrTA)的电子束研究,研制了一套在CESR真空室中原位测量样品次级电子产额(SEY)的装置。CesrTA原位系统自2010年开始运行,允许SEY测量作为暴露于加速器环境的样品上的入射电子能量和角度的函数,通常为5.3 GeV的反向旋转电子束和正电子束。该系统设计用于定期测量,以观察SEY的光束调节,区分暴露于来自同步辐射的直接光子与散射光子和云电子。SEY腔室可以与CESR束管隔离,使我们能够在不对CESR真空腔室排气的情况下交换样品。到目前为止,测量是在金属表面和EC缓解涂层上进行的。SEY测量计划的目标是改进EC积聚和EC诱导束效应的预测模型。本报告描述了CesrTA原位SEY装置、测量工具和技术以及其中的迭代改进。

英文摘要:

The achievable beam current and beam quality of a particle accelerator can be limited by the build-up of an electron cloud (EC) in the vacuum chamber. Secondary electron emission from the walls of the vacuum chamber can contribute to the growth of the electron cloud. An apparatus for in-situ measurements of the secondary electron yield (SEY) of samples in the vacuum chamber of the Cornell Electron Storage Ring (CESR) has been developed in connection with EC studies for the CESR Test Accelerator program (CesrTA). The CesrTA in-situ system, in operation since 2010, allows for SEY measurements as a function of incident electron energy and angle on samples that are exposed to the accelerator environment, typically 5.3 GeV counter-rotating beams of electrons and positrons. The system was designed for periodic measurements to observe beam conditioning of the SEY with discrimination between exposure to direct photons from synchrotron radiation versus scattered photons and cloud electrons. The SEY chambers can be isolated from the CESR beam pipe, allowing us to exchange samples without venting the CESR vacuum chamber. Measurements so far have been on metal surfaces and EC-mitigation coatings. The goal of the SEY measurement program is to improve predictive models for EC build-up and EC-induced beam effects. This report describes the CesrTA in-situ SEY apparatus, the measurement tool and techniques, and iterative improvements therein.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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