Dynamic charging behavior of dielectric surfaces induced by electron beam irradiation and its effect on multipacting

Spacecraft components working in a complex plasma environment in space environment, and the dielectric modules in the components face the important issue of surface charging. In this work, we quantitatively study the surface potential evolution for dielectrics. The results show that continuous irradiation by the electron beam causes the dielectric surface to reach a balance state, and the balance surface potential is significantly affected by the initial surface potential, the primary electron energy of the incident electrons, and the second critical energy (E_p2) of the dielectric. Calculation results show that irradiating uncharged Al₂O₃ sheet continuously with an electron beam of 15,000 eV energy can reach a surface potential of - 9501.01 V, which is a risky high potential. While the balance potential of MgO sheet under the same irradiation condition is only - 1632.34 V, indicating that dielectrics with higher E_p2 are more favorable for mitigating surface charging. Besides, at electron landing energies below E_p2, the surface potentials due to irradiation are too low to induce electrostatic discharge. Multipacting simulations for coaxial filters filled with Al₂O₃ sheets show that the first critical energy (E_p1) of the dielectric is affected by the surface potential and further influences the device multipacting threshold. A surface potential of + 20 V/- 80 causes the E_p1 of Al₂O₃ sheets to drop/increase from 40 eV to 20 V/120 eV, resulting in a decrease/increase in the filter multipacting threshold from 173.4 to 145.3 W/318.4 W. The work is valuable for researching the dynamic charging behavior of dielectric surfaces, and for the engineering application of dielectric multipacting in microwave devices.