Patent Number: 041785240
Section: abstract

This disclosure is directed to a radioisotope photoelectric generator for producing electrical energy. The construction of the generator is similar to that of a well-known storage battery. The generator is composed of alternate layers of high-Z, (high atomic-number) and low-Z(low atomic number) material which are insulated by vacuum or other insulating material. Low-energy photons from a radioactive source interact predominantly with the high-Z material by the photoelectric process, ejecting photoelectrons whose energy extends up to the incident gamma-ray energy E. By selecting the high-Z material thickness to be less than one electron range (at energy E) and the low-Z material thickness to be more than one electron range, there is a net electron transfer from the high-Z plates to the low-Z plates because electrons are emitted predominantly from the high-Z plates and stop in the low-Z plates. After start-up, a potential difference will build up between the high-Z and low-Z plates. An upper limit for this potential difference in kilovolts is the energy E in keV. The high-Z plates are connected together electrically and the low-Z plates are connected together electrically thus forming a "battery. " The "battery" delivers power to an external electrical load, preferably but not necessarily a resistor, whose value is chosen to maximize the power delivered to the electrical load, to yield the voltage desired, to control the temperature of the plates, or a combination of such considerations.