Effective decrease of photoelectric emission threshold from gold plated surfaces

Abstract

Many applications require charge neutralisation 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 ($\sim 5.1$\,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 4.6x4.6 cm^2 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 a ~0.3 cm^2 of the central surface region at angles of incidence from 0 to 60 degrees. Final extrinsic quantum yields in the range 10 ppm to 44 ppm were reliably obtained during 8 campaigns, covering a ~3 year period, 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^{-7} mbar at room temperature. A working model, designed to allow accurate simulation of any experimental configuration, is proposed.

35 pages, 12 figures

References in corpus (8)

• TianQin: a space-borne gravitational wave detector
• Beyond LISA: Exploring Future Gravitational Wave Missions
• Precision Charge Control for Isolated Free-Falling Test Masses: LISA Pathfinder Results
• Charge Management for Gravitational Wave Observatories using UV LEDs
• Characterising and Testing Deep UV LEDs for Use in Space Applications
• Ground Testing and Flight Demonstration of Charge Management of Insulated Test Masses Using UV LED Electron Photoemission
• Energy distribution and quantum yield for photoemission from air-contaminated gold surfaces under UV illumination close to the threshold
• Lifetime Testing UV LEDs for Use in the LISA Charge Management System

Cited by in corpus (5)

• Numerical Modeling and Experimental Demonstration of Pulsed Charge Control for the Space Inertial Sensor used in LISA
• The role of low-energy electrons in the charging process of LISA test masses
• Simulating the charging of isolated free-falling masses from TeV to eV energies: detailed comparison with LISA Pathfinder results
• Advancements in Secondary and Backscattered Electron Energy Spectra and Yields Analysis: from Theory to Applications
• Two Approaches for the Passive Charge Management of Contactless Test Masses