Development of a Measurement System for the Secondary Electron Emission Yield Spectrum of Space Materials

When a spacecraft is operating in space orbit, the phenomenon of secondary electron emission will occur under the influence of charged particles in space, causing the surface of the spacecraft to charge, and long-term accumulation will cause damage to the spacecraft and its instruments. In response to the needs of spacecraft live protection and life evaluation, this paper has researched the secondary electron emission yield spectrum test technology of space materials and completed the development of the test system. Firstly, we use an electron gun with an energy range of 0-2000eV, a beam current of 1nA-10μA, and a minimum beam spot diameter of 0.5mm to achieve stable electron beam current in the secondary electron emission coefficient measurement system in this paper. Secondly, the vacuum system uses mechanical pumps, molecular pumps, and sputtering ion pump, so that it can reach a vacuum of 1×10^-6pa. Thirdly, the measurement scheme of vacuum secondary electron collecting ball and grid structure is proposed for the first time, which can realize the distinguished collection and measurement of true secondary electrons and backscattered secondary electrons. Finally, the measurement of the secondary electron yield spectrum of metal materials was studied, and the efficient measurement of the secondary electron emission yield spectrum of oxygen-free copper and gold materials was completed. The test results have reached that the secondary electron emission yield spectrum data of Cu and Au samples under 0-2000eV incident electrons is consistent with the literature, which verifies the reliability of the test system.