164 Electrical Power Systems Technology
is the nuclear cell. Such cells convert the energy given off by atomic nu-
clei into electrical energy. At present, a high-voltage type (thousands of
volts with a picoampere current capacity) and a low-voltage type (approx-
imately 1 volt with a microampere current capability) are available.
The illustration in Figure 7-6 shows the design of one type of nuclear
cell. The radioactive source is connected to one electrode of the cell. The
source used here is tritium gas absorbed in zirconium metal, which emits
beta particles. The carbon-collector electrode collects these beta particles
as they are emitted from the tritium source, thus producing an electrical
charge. The electrodes are separated by either a vacuum or some other
type of dielectric, which electrically isolates the two electrodes. The nu-
Figure 7-5. Alkaline cells: Cutaway of a cylindrical alkaline cell (Courtesy
Eveready Corp.)