Experimental optimization of small–scale structure–adjustable radioisotope thermoelectric generators

Abstract Small–scale radioisotope thermoelectric generators (RTGs) offer a flexible and scalable power supply for space missions. However, high-performance small-sized RTGs remain challenging. The performance of thermoelectric materials was optimized by Taguchi orthogonal method in this work. Three preparation parameters, including the slurry ratio, cold pressing pressure, and the sintering temperature, along with 4 levels were taken into account. The orthogonal array quickly determined the sensitivity of the performance to the variations of 3 factors. The influences of 3 factors on the ZT value were ranked as: cold pressing pressure > slurry ratio > sintering temperature. The optimum operation was 10% paint proportion, 35 MPa pressure, and 598.15 K sintering temperature. Based on this, the optimal ZT values of the P/N–type thermoelectric materials reached 0.92 and 1.03 at room temperature, respectively. The principle prototype of the fan–shaped and annular RTGs were well prepared by the cold sintering and molding methods. Those RTGs obtained open–circuit voltages of 1.17 and 1.56 V, and maximum output powers of 1.9 and 3.39 mW at 398.15 K. These stable and adequate energy is able to directly power for meteorological monitoring equipment, seismometer, and microsatellites.