Microwatt Radioisotope Energy Converters

After a brief survey of proposed radioisotope conversion systems this paper presents in detail two systems particularly suited for microwatt power sources. First, a 10-9 ampere Kr85 ß current cell capable of tens of kilovolts now in limited production is presented, followed by a discussion of other possible future ß current cells. Second, some theoretical considerations of a Pm147 silicon electronvoltaic converter with an output in the range of 100 ¿A/cm2 at a few tenths of a volt are discussed. Some applications adapted to each system are also presented.