Temperature flattening and thermoelectric conversion modeling of TOPAZ-II thermionic reactor

Focus on temperature non-uniformity in thermionic reactors, a code for temperature flattening is developed by taking the 100 kW TOPAZ-II thermionic reactor as an example. Two optimization schemes, central hole and fuel enrichment, were implemented. Comparison with experiments shows the model can predict temperature distribution and volt–ampere characteristics. After optimization, emitter temperature and current density are more concentrated. The maximum temperatures of central hole and enrichment schemes are reduced to 1905 K and 1940 K from 1990 K. The optimized reactor can operate at higher power density. At 2000 K emitter maximum temperature, the powers of central hole and enrichment schemes increase by 21.95% and 12.59%. A comparative study shows that increasing emitter maximum temperature from 1800 K to 2000 K can increase reactor energy conversion efficiency from 6.83% to 7.91%.