NETCON: A HIGH EFFICIENCY THERMIONIC CONVERTER FOR A RADIOISOTOE HEAT SOURCE

DIRECT ENERGY CONVERSION SYSTEMS ARE OF INTEREST FOR USE WITH RADIOISOTOPE HEAT SOURCES BECAUSE THESE SYSTEMS CAN SIGNIFICANTLY EXCEED THE 6 TO 8% EFFICIENCY OF STATE-OF-THE-ART THERMOELECTRIC SYSTEMS. CONVENTIONAL THERMIONIC ENERGY CONVERTERS, IN GENERAL, DO NOT OPERATE EFFICIENTLY AT STATE-OF-THE-ART GENERAL PURPOSE HEAT SOURCE (GPHS) SURFACE TEMPERATURES OF 1,350 TO 1,400 K. A NEW CONCEPT (NETCON), WHICH CAN ACHIEVE GOOD EFFICIENCY AT LOW EMITTER TEMPERATURE IN AN OUT-OF-CORE POWER CONVERSION SYSTEM, HAS BEEN DEVELOPED RECENTLY. NETCON OPERATES IN A QUASIVACUUM MODE, ACHIEVING HIGH ELECTRODE EFFICIENCY BECAUSE THERE IS NO PLASMA ARC DROP. THE EMITTER AND COLLECTOR SURFACES ARE PROVEN MATERIALS (E.G., TUNGSTEN, MOLYBDENUM, ETC.). THE HOT-SIDE TEMPERATURE IS TYPICAL OF GPHS SURFACE TEMPERATURES (1,350 TO 1,400 K). IN PHASE I OF THIS RESEARCH, A MODEL OF THE NETCON CONCEPT IS BEING DEVELOPED, AND A NETCON CONVERTER IS BEING DESIGNED, FABRICATED, AND TESTED. ALSO, THE TECHNOLOGIES REQUIRED FORMANUFACTURING AND INCORPORATING THE DEVICE IN A SYSTEM ARE BEING INVESTIGATED. FROM THE RESULTS OF PHASE I, A PLAN WILL BE DEVELOPED FOR THE APPLICATION OF THE NETCON IN A GPHS SYSTEM IN PHASE II.