Wass Peter J, Hollington Daniel, Sumner Timothy J, Yang Fangchao, Pfeil Markus
High Energy Physics Group, Physics Department, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom.
Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan, Hubei 430074, China.
Rev Sci Instrum. 2019 Jun;90(6):064501. doi: 10.1063/1.5088135.
Many applications require charge neutralization of isolated test bodies, and this has been successfully done using photoelectric emission from surfaces which are electrically benign (gold) or superconducting (niobium). Gold surfaces nominally have a high work function (∼5.1 eV) which should require deep UV photons for photoemission. In practice, it has been found that it can be achieved with somewhat lower energy photons with indicative work functions of (4.1-4.3 eV). A detailed working understanding of the process is lacking, and this work reports on a study of the photoelectric emission properties of 4.6 × 4.6 cm gold plated surfaces, representative of those used in typical satellite applications with a film thickness of 800 nm, and measured surface roughnesses between 7 and 340 nm. Various UV sources with photon energies from 4.8 to 6.2 eV and power outputs from 1 nW to 1000 nW illuminated ∼0.3 cm of the central surface region at angles of incidence from 0° to 60°. Final extrinsic quantum yields in the range 10 ppm-44 ppm were reliably obtained during 8 campaigns, covering a period of ∼3 years but with intermediate long-term variations lasting several weeks and, in some cases, bake-out procedures at up to 200 °C. Experimental results were obtained in a vacuum system with a baseline pressure of ∼10 mbar at room temperature. A working model, designed to allow accurate simulation of any experimental configuration, is proposed.
许多应用需要对孤立的测试体进行电荷中和，利用来自电性能良好的表面（金）或超导表面（铌）的光电发射已成功实现这一点。金表面的标称功函数较高（约5.1电子伏特），这意味着光发射需要深紫外光子。实际上，已发现用指示功函数为（4.1 - 4.3电子伏特）的能量稍低的光子也能实现。目前尚缺乏对该过程的详细工作理解，本文报道了一项对4.6×4.6厘米镀金表面光电发射特性的研究，这些表面代表了典型卫星应用中使用的表面，膜厚为800纳米，测量的表面粗糙度在7至340纳米之间。各种光子能量在4.8至6.2电子伏特、功率输出在1纳瓦至1000纳瓦之间的紫外光源，以0°至60°的入射角照射中心表面区域约0.3厘米。在8次实验中可靠地获得了10 ppm至44 ppm范围内的最终非本征量子产率，实验持续约3年，但存在持续数周的中期长期变化，在某些情况下，还进行了高达200°C的烘烤程序。实验结果是在室温下基线压力约为10毫巴的真空系统中获得的。本文提出了一个工作模型，旨在能够精确模拟任何实验配置。
