Influence of primary electron incident angle and electron bombardment on the secondary electron yield of laser-treated copper

Electron cloud is a persistent problem in operating modern accelerators. It might be eliminated by reducing the secondary electron yield (SEY), which is a property of the material of vacuum chambers. In the present study, the SEYs of oxygen-free copper samples are dramatically mitigated by grooving their surfaces with a laser-etching technique. Such mitigation is realized by trapping incident primary electrons and their induced secondary electrons in the grooves. The SEYs of the laser-etched samples are dependent on the geometrical characteristics of the grooves and the incident angles of the primary electrons, i.e., reducing the incident angle can lead to a reduction in the SEY. Electron bombardment of the grooved surface with an electron dose of 2 × 10−2 C mm−2 will further reduce its maximum SEY from 1.15 to 0.98, which might be attributed to the formation of Cu2O and graphite-like C—C bonds and the removal of surface contaminants.