The present work is to develop an infra-red (IR) camera based in situ diagnostic tool for the determination of cesium (Cs) coverage suitable for ion source applications. Cs seeding is done to reduce the surface work function that enhances the surface assisted negative hydrogen ion production. The temporal Cs deposition on a metal surface (for, e.g., tungsten or molybdenum) follows Langmuir adsorption isotherm (LAI) kind of behavior. The surface temperature varies while the Cs deposition is reflected in the IR camera temperature measurements for a constant surface emissivity value. In this paper, a model on the relationship between Cs coverage in correlation with surface emissivity and temperature variation based on the theory of LAI is presented. A surface ionization probe (SIP) in the form of a cathode-anode assembly together with an IR camera viewing arrangement is designed to measure the Cs flux and the surface temperature simultaneously to test our model. In the present experiment, the Cs flux measurement using SIP is validated with a standard quartz crystal microbalance (QCM). The proposed model would be useful to correlate Cs coverage on plasma grid-like surface conditions under negative ion source relevant vacuum conditions.

中文翻译：

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使用真空下红外成像实时原位估计金属基板上铯覆盖率的模型

目前的工作是开发一种基于红外 (IR) 相机的原位诊断工具，用于确定适用于离子源应用的铯 (Cs) 覆盖率。进行 Cs 晶种以降低表面功函数，从而增强表面辅助负氢离子的产生。金属表面（例如，钨或钼）上的时间 Cs 沉积遵循朗缪尔吸附等温线 (LAI) 类型的行为。表面温度会发生变化，而 Cs 沉积会反映在 IR 相机温度测量中，以获得恒定的表面发射率值。在本文中，基于LAI理论，提出了Cs覆盖率与表面发射率和温度变化相关的关系模型。阴极-阳极组件形式的表面电离探针 (SIP) 与 IR 摄像机观察装置一起设计用于同时测量 Cs 通量和表面温度以测试我们的模型。在本实验中，使用 SIP 的 Cs 通量测量通过标准石英晶体微量天平 (QCM) 进行验证。所提出的模型将有助于在负离子源相关真空条件下将 Cs 覆盖与等离子体网格状表面条件相关联。