Demonstration of a compact, self-contained, glass-encapsulated thermionic energy converter with an n-type AlGaN cathode

Abstract This study demonstrates a compact, self-contained, glass-encapsulated prototype thermionic energy converter (TEC) operating at around 300 °C, a remarkably low temperature for thermionic power generation. The device employs an n-type AlGaN thermionic cathode and is hermetically sealed in a glass-sealed Kovar package with a 3‑cm‑diameter base. It consists of the AlGaN cathode, a perforated SUS anode, and a vacuum gap defined by insulating beads, together with an internal Cs accumulation region. Upon heating to 302 °C, the TEC produced an open-circuit voltage of 0.33 V and a short-circuit current density of 1.3 μA cm −2 .