Experimental confirmation of milliwatt power source concept

The results of development and tests of mini RTG, milliwatt power source (PS) are presented. The development of PS model is based on the standard Light Weight Radioisotope Heater Unit (RHU) of 1.0 W thermal power, fueled by Plutonium-238. This RHU was successfully used on the spacecraft Galileo, Cassini, Mars Pathfinder etc. The computations were carried out and the optimum parameters of PS, for which maximum power can be achieved, were determined. Experimental samples of two PS modifications, equipped with electrical equivalents of RHU and thermoelectric batteries (TEB) made of Bi-Te-Sb-Se alloys, were fabricated: PS-1 (with one RPIU) and PS-2 (with two RI-IUs). The results of experimental tests have confirmed that an electrical power level of 25 mW can be achieved in PS-I and of 53 mW-in PS-2. The analysis of the calculations and experiments shows that the electrical power of PS-2 can be increased up to 70 mW at 5 V.