Energy from Nuclear Particles
As we have seen, solar cells are able to convert the kinetic energy of charged nuclear particles directly into electricity, but a simpler and more straightforward way of doing this exists. This involves direct use of the flow of charged particles as current.
The nuclear battery shown in [Figure 13] performs this trick. A central rod is coated with an electron-emitting radioisotope (a beta-emitter; say, strontium-90). The high-velocity electrons emitted by the radioisotope cross the gap between the cylinders and are collected by a simple metallic sleeve and sent to the load. Simple, but why don’t space charge effects prevent the electrons from crossing the gap as they do in the thermionic converter? The answer lies in the fact that the nuclear electrons have a million times more kinetic energy than those boiled off the thermionic converter’s emitter surface. Consequently, they are too powerful to be stopped by any space charge in the narrow gap.
Nuclear batteries are simple and rugged. They generate only microamperes of current at 10,000 to 100,000 volts.
Figure 13 A NUCLEAR BATTERY
The nuclear battery depends upon the emission of charged particles from a surface coated with a radioisotope. The particles are collected on another surface.
ENERGY OUT INSULATOR LAYER OF BETA-EMITTING RADIOISOTOPE VACUUM