Study on Secondary Electron Emission of High Power Microwave Ferrite Materials

In recent years, microwave ferrite devices such as circulators, isolators and phase shifters have also been widely used in microwave and radio frequency band. Secondary electron emission (SEE) yield is one of most important parameters for multipactor in high power ferrite device. In this paper, we are presenting a system to measure SEE yield of ferrite materials at primary energies of 30eV to 3keV. According to the measurement, the decrease of secondary electron current under constant primary electron irradiation is because of surface charging. In order to minimize the impact of the surface charging, the primary electron beam had a short pulse of length 10 microseconds with a pulse interval of 1 second to release the charges on the sample. The SEE yield increased with the primary energy for low energies, then went to the maximum value 2.5 at primary electron energy of 300eV, and finally decreased for high primary energies, which is in accordance with the universal curve of SEE yield.