<P> Non-thermal converters extract a fraction of the nuclear energy as it is being degraded into heat . Their outputs are not functions of temperature differences as are thermoelectric and thermionic converters . Non-thermal generators can be grouped into three classes . </P> <P> In the first type, the primary generator consists of a capacitor which is charged by the current of charged particles from a radioactive layer deposited on one of the electrodes . Spacing can be either vacuum or dielectric . Negatively charged beta particles or positively charged alpha particles, positrons or fission fragments may be utilized . Although this form of nuclear - electric generator dates back to 1913, few applications have been found in the past for the extremely low currents and inconveniently high voltages provided by direct charging generators . Oscillator / transformer systems are employed to reduce the voltages, then rectifiers are used to transform the AC power back to direct current . </P> <P> English physicist H.G.J. Moseley constructed the first of these . Moseley's apparatus consisted of a glass globe silvered on the inside with a radium emitter mounted on the tip of a wire at the center . The charged particles from the radium created a flow of electricity as they moved quickly from the radium to the inside surface of the sphere . As late as 1945 the Moseley model guided other efforts to build experimental batteries generating electricity from the emissions of radioactive elements . </P> <P> Betavoltaics are generators of electric current, in effect a form of battery, which use energy from a radioactive source emitting beta particles (electrons). A common source used is the hydrogen isotope, tritium . Unlike most nuclear power sources, which use nuclear radiation to generate heat, which then generates electricity (thermoelectric and thermionic sources), betavoltaics use a non-thermal conversion process, using a semiconductor p-n junction . </P>

What was the purpose of the atomic battery