Modern designs of atomic bombs contain, in addition to uranium or plutonium, small amounts of tritium and deuterium to boost the power of explosion. What is the role of tritium and deuterium in these bombs?

Nuclear fission is a critical process in the operation of atomic bombs. In essence, fission is the splitting of a large atomic nucleus into smaller fragments. This is typically achieved in atomic bombs by using heavy elements such as uranium or plutonium. When these atoms are bombarded with neutrons, their nuclei become unstable and split into two smaller nuclei, releasing more neutrons and a tremendous amount of energy in the process. The release of this energy in a short amount of time is what creates the destructive force of an atomic bomb.

The energy released is so significant because it partly comes from the mass of the nucleus itself, according to the famous equation by Einstein, \(E = mc^2\) where \(E\) is energy, \(m\) is mass, and \(c\) is the speed of light. Though the total mass loss might be small, the conversion of even a tiny amount of mass into energy can lead to a huge explosion because the speed of light \(c\) is quite large.

Tritium, with the chemical symbol \(^3H\) or \(T\) is a heavy isotope of hydrogen that has one proton and two neutrons in its nucleus. It's radioactive and has a half-life of about 12.32 years, meaning it decays over time by releasing particles. In the context of nuclear bombs, tritium is essential for boosting the efficiency of the explosion. It serves as a fuel for the thermonuclear reaction which occurs after the initial fission reaction. Tritium can be seen as the 'spark' that significantly enhances the energy output of the bomb.

The utilization of tritium in the bomb allows for an increase in the rapidity and intensity of the thermonuclear reactions, which ultimately contributes to a larger, more powerful explosion. The presence of tritium enables the thermonuclear reactions to proceed even when the conditions are not fully ideal for fusion, as can be the case during the chaotic environment of an exploding bomb.

Deuterium, denoted as \(^2H\) or \(D\) is another isotope of hydrogen, consisting of one proton and one neutron. It is commonly found in 'heavy water', with a natural abundance in earth's water of about 0.015%. In atomic bombs, deuterium acts synergistically with tritium in the fusion reaction.

When a deuterium nucleus fuses with a tritium nucleus, they form a helium-4 nucleus and release a free neutron along with a significant amount of energy. This fusion reaction, supported by deuterium, releases energy that further drives the chain reaction of fission in the plutonium or uranium core. It's a collaborative process where the fission triggers the fusion of deuterium and tritium, and the resulting energy from the fusion amplifies the overall blast of the bomb.

Thermonuclear reactions are at the heart of both the sun's energy production and the explosive power of hydrogen bombs. These reactions involve the fusion of light atomic nuclei into heavier nuclei, releasing energy in the process.

In the controlled environment of the sun, the fusion of hydrogen into helium provides long-lasting energy output. In the extreme and uncontrolled environment of a hydrogen bomb, similar fusion reactions occur rapidly, resulting in an overwhelming release of energy. This type of bomb, which uses isotopes like deuterium and tritium, is often referred to as a 'thermonuclear' bomb because of these high-temperature fusion reactions. The fusion process in a hydrogen bomb is initiated by the preceding fission explosion, which provides the necessary heat and pressure. This represents a two-stage process: the first being the triggering fission explosion, and the second being the fusion of deuterium and tritium—which tremendously magnifies the explosive yield of the bomb.