Abstract: Various disclosed embodiments include thermionic energy converters with a thermal concentrating hot shell and emitters for thermionic energy converters. In some embodiments, an illustrative thermionic energy converter includes: an emitter electrode; a hot shell configured to concentrate heat flow toward the emitter electrode; a collector electrode; and a cold shell that is thermally isolated from the hot shell.

Abstract: Disclosed embodiments include vacuum electronic devices, methods of operating a vacuum electronic device, and methods of fabricating a vacuum electronic device. In a non-limiting embodiment, a vacuum electronics device includes a cathode and an anode. At least one focus grid is disposed between the cathode and the anode, and the at least one focus grid is physically disconnected from the cathode. The at least one acceleration grid is disposed between the cathode and the anode, and the at least one acceleration grid is further disposed adjacent the at least one focus grid. The at least one acceleration grid is physically disconnected from the cathode.

Abstract: Disclosed embodiments include conductive oxide-coated electrodes and methods of fabricating a conductive oxide-coated electrode. In a non-limiting embodiment, a conductive oxide-coated electrode includes: a conductive layer; and an oxide coating disposed on the conductive layer. In another non-limiting embodiment, a method of fabricating a conductive oxide-coated electrode includes: patterning a conductive layer; etching the patterned conductive layer; and disposing an oxide coating on the etched conductive layer.

Abstract: Various disclosed embodiments include thermionic energy converters with a thermal concentrating hot shell and emitters for thermionic energy converters. In some embodiments, an illustrative thermionic energy converter includes: an emitter electrode; a hot shell configured to concentrate heat flow toward the emitter electrode; a collector electrode; and a cold shell that is thermally isolated from the hot shell.

Abstract: Disclosed embodiments include vacuum electronics devices and methods of fabricating a vacuum electronics device. In a non-limiting embodiment, a vacuum electronics device includes: an electrode; a first film layer disposed on the electrode about a periphery of the electrode; and a second film layer disposed on the first film layer, the second film layer including a plurality of electrically conductive grid lines patterned therein that are supported only at the periphery of the electrode by the first film layer.