Synergistic Suppression of Secondary Electron Yield from Al2O3 Ceramic Windows by TiN Film and Laser Surface Texturing

To suppress the Secondary Electron Yield (SEY) of Al2O3 ceramic surfaces for accelerator ceramic windows, a synergistic strategy integrating TiN film deposition and laser surface texturing was developed. TiN films were first deposited on Al2O3 substrates by pulsed DC magnetron sputtering, and the sputtering power was optimized through systematic characterization of the film morphology and chemical states, with 300 W identified as the optimal deposition condition. Laser surface texturing was then introduced to construct micro-structured Al2O3 surfaces with different geometrical features. Among the investigated laser powers, the 12 W-treated surface exhibited the most developed surface morphology and the highest roughness, indicating the most favorable topography for electron trapping. SEY measurements showed that the maximum SEY decreased from 8.2 for the as-received Al2O3 to 5.5 after deposition of a 10 nm TiN film, and was further reduced to 2.1, 1.0, and 1.7 for the textured TiN/Al2O3 surfaces prepared at 6, 12, and 18 W, respectively, with the best suppression for the 12 W textured TiN/Al2O3. The enhanced performance is attributed to the synergistic effect of low-SEY TiN surface chemistry and geometrical electron trapping induced by laser texturing. This work provides an effective route for constructing low-SEY Al2O3 ceramic surfaces for beam-window-related applications.