Ceramic spacers with a high aspect ratio (80 mu m/1.1 mm) were fabricated and laid out in a high voltage 5.2 in. field emission display (FED) panel. Alumina was chosen as spacer material and sintered at 1600 degrees C for high mechanical strength and suitable electric resistivity. Three different types of spacers, single-trench type, double-trench type, and honey-comb types, were considered in this study. We optimized the structure and the layout of spacers in terms of stress distributions, build up profiles of glass, carrier gas flows inside a panel. Among the three different types of spacers, the double-trench structure spacer provided the most uniform gas flow and the highest mechanical strength. The optimal number of spacers with 80 mu m width and 1.1 mm height was found to be 7 for an uniform stress distribution in a 5.2 in. FED panel by experiments and computer simulations.