Characterization of materials with low secondary electron yield for use in high-power microwave devices

Abstract

Summary form only given. A completely automated high vacuum system has been set up to measure the secondary electron yield (SEY) of different materials. Secondary electron emission results from bombarding materials with atoms, electrons or ions. SEY is defined as the number of secondary electrons produced per incident primary electron. Focus is on the measurement of materials with low SEY for use in depressed collectors in high-power microwave devices. Initial experiments are concentrated on the low energy range from 10 eV-1000 eV using an electron gun operating in continuous mode. SEY of pure copper, plasma sprayed boron carbide (PSBC) and titanium nitride (TiN) have been obtained. SEY for angular incidences - up to 45 degrees - have been obtained for the PSBC sample. Reflections of primary electrons at energies below 200 eV have been resolved for PSBC. The effects of surface morphology on SEY have been quantified by ablating the surface using a class four Nd:YAG laser. Comparisons of results with formulae proposed in literature are also presented