Fundamental experiment of micro thermionic power generator with narrow gap

In this research we fabricated a thermionic power generator with 10 μm gap. The thermionic power generator has an emitter and a collector. The emitter and the collector are separated with the gap via insulation spacers. A Si wafer coated by a W thin film was used as the emitter, and a Pt-coated Si wafer was used as the collector substrate. The thermionic power generator placed in a vacuum chamber, Cs gas was introduced to the chamber to enhance emission and its output characteristics are evaluated. When the emitter with an area of 25 mm2 is heated to about 980°C by lamp heater, and temperature of the collector increases at 440°C. A maximum output of about 1.3 mW is obtained when a load resistance of 11.1 Ω is connected to the output terminal. The theoretical output of this thermionic power generator is calculated to be about 2 W. The experimental efficiency of the thermionic power generator is about 0.01%.