Nuclear Fusion

Scientists who worked on the first fission (atomic) bomb during World War II were aware of the potential for building an even more powerful bomb that operated on fusion principles. Here is how it would work.

The JET (Joint European Torus) nucelar fusion reactor. Photo Researchers, Inc. Reproduced by permission.

The core of the fusion bomb would consist of a fission bomb, such as the one they were then developing. That core could then be surrounded by a casing filled with isotopes of hydrogen. Isotopes of hydrogen are various forms of hydrogen that all have a single proton in their nucleus, but may have zero, one, or two neutrons. The nuclei of the hydrogen isotopes are the proton, the deuteron, and the triton.

Imagine that a device such as the one described here could be exploded. In the first fraction of a second, the fission bomb would explode, releasing huge amounts of energy. In fact, the temperature at the heart of the fission bomb would reach a few millions degrees, the only way that humans know of for producing such high temperatures.

That temperature would not last very long, but in the microseconds that it did exist, it would provide the energy for fusion to begin to occur within the casing surrounding the fission bomb. Protons, deuterons, and tritons would begin fusing with each other, releasing more energy, and initiating other fusion reactions among other hydrogen isotopes. The original explosion of the fission bomb would have ignited a small star-like reaction in the casing surrounding it.

From a military standpoint, the fusion bomb had one powerful advantage over the fission bomb. For technical reasons, there is a limit to the size one can make a fission bomb. But there is no technical limit on the size of a fusion bomb. One simply makes the casing surrounding the fission bomb larger and larger, until there is no longer a way to lift the bomb into the air so that it can be dropped on an enemy.

On August 20, 1953, the Soviet Union announced the detonation of the world's first fusion bomb. It was about 1,000 times more powerful than was the fission bomb that had been dropped on Hiroshima less than a decade earlier. The Soviet Union (now Russia) and the United States became proficient at manufacturing fusion bombs on an almost assembly-line schedule.