Optimization of the secondary electron yield of laser-structured copper surfaces at room and cryogenic temperature
Optimization of the secondary electron yield of laser-structured copper surfaces at room and cryogenic temperature
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DOI：
10.1103/physrevaccelbeams.23.033101
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发表时间：
2020-03-11
影响因子：
1.7
通讯作者：
Abdolvand, Amin
中科院分区：
文献类型：
--
作者：
Calatroni, Sergio;Valdivieso, Elisa Garcia-Tabares;Abdolvand, Amin
为了保证束流在高强度下的稳定性和限制低温截面上的热负荷，电子云(e云)的缓解是质子循环加速器的基本要求。激光工程表面结构被认为是一种可靠的过程，可以降低面对束流表面的二次电子产额(SEY)，从而抑制欧洲核子研究中心(HL-LHC)LHC对撞机(HL-LHC)高亮度升级中的e云现象。在本研究中，测量了不同氧化状态的铜样品在室温和低温下的SEY，并与X射线光电子能谱测量的表面成分进行了关联。结果表明，氮气处理的样品的SEY值最低且更稳定，与较低的表面氧化程度相关。此外，空气处理样品的表面氧化层在低温下电子暴露时带电，导致SEY的波动。
Electron cloud (e-cloud) mitigation is an essential requirement for proton circular accelerators in order to guarantee beam stability at a high intensity and limit the heat load on cryogenic sections. Laser-engineered surface structuring is considered a credible process to reduce the secondary electron yield (SEY) of the surfaces facing the beam, thus suppressing the e-cloud phenomenon within the high luminosity upgrade of the LHC collider at CERN (HL-LHC). In this study, the SEY of Cu samples with different oxidation states, obtained either through laser treatment in air or in different gas atmospheres or via thermal annealing, has been measured at room and cryogenic temperatures and correlated with the surface composition measured by x-ray photoelectron spectroscopy. It was observed that samples treated in nitrogen display the lowest and more stable SEY values, correlated with the lower surface oxidation. In addition, the surface oxide layer of air-treated samples charges upon electron exposure at a low temperature, leading to fluctuations in the SEY.