Abstract
A nuclear battery is made which is composed of five silicon p-n junctions, five 147Pm beta sources, and a SUS 27 container. Maximum output power and overall efficiency of energy conversion are obtained as 1.2μW and 0.3%, respectively. The effective source activity is 0.1-0.2 Ci for each 147Pm source. The small output power is caused by the weak 147Pm beta sources.
Electrical characteristics of a p-n junction element are measured by using monoenergetic electron beam of which energy was 50, 75, and 100 ke V. The result shows that the maximum output power, P0, and the input power of the electron beam, Pe, has a relation as P0=Pex, where x is equal to 1.2-1.3.
Optimum junction depth for beta rays from 147Pm to obtain maximum output power is determined as 2 to 4 microns from the surface of the junction.
Reduction of the maximum output power of the p-n junction element caused by radiation damage has been measured during 6200 hours. The experimental result shows that the decrease of the maximum output power is only 5% during 6200 hours.
