Photoelectron Emission Yield of Au Film: Theoretical Calculation and Measurement

Spacecraft in orbit are exposed to intense solar radiation in the space environment, causing the material surface to be charged and damaged. The incident electrons, ions, and photons on the surface of spacecraft materials produce secondary electrons, backscattered electrons, photoelectrons, and so on. The damage to the material caused by the emitted photocurrent is more serious when the incident energy is higher than the photoelectric threshold. In view of the significant threat of particle radiation to the charge protection and operational life of spacecraft materials, in this article, a theoretical model of the photoelectron emission yield (PEEY) is studied, and a test system of metal materials under ultraviolet light is developed. First, we derive a three-step model of the photoemission of metal materials and calculate the PEEY spectrum of Au. Second, the optical system is built by using a deuterium lamp, a monochromator, and an aperture. The installation structure of the photodiode is designed, and the photon number is obtained by measuring the incident luminous flux. Third, a central through-hole microchannel plate is used and a voltage division circuit module is designed to realize effective collection of photoelectrons emitted from the sample surface. This approach realizes a detectable range for an Au film from 10−4 to 10−7 el./ph in the spectral range of 130–258 nm. The reliability of the test system is proved by comparing the experimental results with the theoretical results.