Abstract: An improvement is set forth in a thermionic fuel element which includes a collector base supporting a collector adjacent and closely spaced from an emitter which is supported by an emitter base, the emitter base being adapted to be heated by a heat source. In accordance with the invention a thermal shield structure is located between a portion of the emitter and the collector. The shield structure insulates that portion of the collector opposite the shield structure from receiving at least a portion of the radiation developed by the heat source.

Abstract: A thermionic energy converter comprises an emitter, a transparent collector support generally parallel to an emitting surface of the emitter, a conductive film collector from about 10 to about 3,000 Angstroms in thickness covering a support surface of the collector support, and an enclosure for maintaining a controlled atmosphere in the gap between the conductive film collector and the emitting surface. According to another embodiment an improvement is set forth in a thermionic energy converter comprising an emitter, a collector and an enclosure adapted to maintain a controlled atmosphere in the emitter-collector gap. The improvement comprises an insulator post supportingly attaching the emitter and the collector. The embodiments are advantageously used together.

Abstract: A thermionic converter (10) is set forth which includes an envelope (12) having an electron collector structure (22) attached adjacent to a wall (16). An electron emitter structure (24) is positioned adjacent the collector structure (22) and spaced apart from opposite wall (14). The emitter (24) and collector (22) structures are in a common chamber (20). The emitter structure (24) is heated substantially only by thermal radiation. Very small interelectrode gaps (28) can be maintained utilizing the thermionic converter (10) whereby increased efficiency results.

Abstract: A thermionic fault current limiter utilizes either a vacuum or plasma environment for a plurality of spaced conduction electrodes. The electrode can be supported by insulative spacers with the electrode providing shadow shields for the supporting spacers. Electrode spacing, power density, temperature gradients, and control grids can be utilized for optimum operation and in establishing self-absorption of energy for a desired operating environment. Cesium desorption from the electrode surfaces can be utilized to enhance current termination.

Abstract: In a thermionic converter, means are provided for coupling an electrical lead to at least one of the electrodes thereof. The means include a bus bar and a plurality of distributed leads coupled to the bus bar each of which penetrates through one electrode and are then coupled to the other electrode of the converter in spaced apart relation.