Development of Photoelectron Emission Yield Measurement System for Metal Materials

Because the spacecraft in orbit are exposed to intense solar radiation, it will be affected by factors such as cosmic rays and high-energy particles, causing its material surface to be charged and damaged. And compared to the various currents captured on the surface of the spacecraft, when the incident energy is higher than the photoelectric threshold, the damage of the emitted photocurrent to the material is more serious. Because of the significant threat of particle radiation to the charged protection and operational life of spacecraft material, this paper studied the test method of photoelectron emission yield (PEEY) and developed the corresponding system. During the test, firstly, a deuterium lamp and a vacuum ultraviolet (VUV) monochromator are used to generate light. After splitting, it uses a focusing and collimating device to modulate the light into a parallel beam. Secondly, we use a photodiode to detect the incident light flux to obtain the number of incident photons. Thirdly, the collection plate is applied to realize the useful collection of electrons emitted from the material surface. The response current is read by electrometer with high accuracy and low noise. Finally, the ratio of the number of photoelectrons to the incident photons at a single wavelength is calculated to obtain the PEEY. The result shows that the minimum detectable range of the PEEY of the gold is 10-2 ~ 10-4 el/ph. under VUV radiation, and the reliability of the system is proved by comparative with the literature.