What is a Fusion Bomb?

A fusion bomb is also known as a thermonuclear bomb or hydrogen bomb which releases a large amount of explosive energy during a nuclear chain reaction when the lighter nuclei in it, combine to form heavier nuclei, and a large amount of radiation is released. It is an uncontrolled, self-sustaining nuclear chain reaction where isotopes of hydrogen combine under very high temperature to form helium. They work on the principle of operation of atomic fusion. The isotopes of Hydrogen are deuterium and tritium, where they combine their masses and have greater mass than the product nuclei, get heated at high temperatures, and releases energy.

Nuclear fission is a reaction in which an atomic nucleus of a radioactive element splits due to bombardment from an external source, with the simultaneous release of large amounts of energy. A chain reaction occurs when the element Uranium due to its critical mass undergoes a fission reaction resulting in the release of a large amount of heat and energy that produces an atomic explosion. This is called a fission bomb. Each uranium-235 atom has a mass of 3.9 ×10^-25 kg. The total number of atoms in 1 kg of uranium- 235or U-235 is atoms. Fission means dividing or splitting into smaller parts. 

The fusion bomb undergoes a nuclear fusion reaction in which multiple nuclei join together to form a heavier nucleus. It is generally involved in the absorption of energy depending on the masses of the nuclei involved. The small nuclei come together to form larger nuclei that release a large amount of energy. The energy from the fusion can be calculated as . Using Einstein's energy equation, E=mc², after substituting and calculating the values, E=2.79×10^-12 J.

Sun's energy is also powered by the fusion reaction.

Chain reaction: When a nucleus captures a neutron and splits into fragments and produces three neutrons and the reaction continues.

Critical mass: It is defined as the minimum mass required to sustain the chain reaction.

History of Nuclear Fusion

The first kinds of nuclear weapons were fission weapons called atomic bombs developed during world war II. In November 1952, the hydrogen bomb was exploded for the first time. The hydrogen bomb, a fusion weapon was developed by two of the great scientist, often known as the Teller-Ulam bomb were by Edward Teller and Stanislaw Ulam. During the late 1980s, around 40,000 thermonuclear devices were stored in the world's nuclear-armed nations. The USSR first tested a hydrogen bomb on August 12, 1965. 

Difference between Atom Bomb and Hydrogen Bomb

An atom bomb explodes due to the extreme energy released by nuclear fission reaction while a hydrogen bomb explodes due to the intense energy released by a nuclear fusion reaction. An atom bomb is often known as A-bomb and a Hydrogen bomb is often known as H-bomb. A more complex nuclear reaction takes place in H-bomb than A-bomb. Hydrogen bombs release an extremely high amount of energy and radiation since they include many types of atomic bombs too. While H-bomb uses isotopes like deuterium and tritium in its chain reaction, the atomic bomb uses uranium and plutonium in its nuclear reaction. In an atomic bomb, nuclear explosions are hard to determine while Hydrogen bombs are 1000 times powerful than the atomic bombs and produce a strong shock wave.

First Tests of H-bomb

The hydrogen bomb's first test was called 'Ivy Mike', full scale thermonuclear device that was detonated on November 1 1952, in USA. It produced an explosive yield value of 12 megatons. The A-bomb test was called the 'Ivy King test'.

Components of H-bomb

Nuclear reactors are the components to keep the chain reaction sustaining without any leakage or going out of control. In a nuclear power plant, fission reaction occurs in a separate chamber and it produces energy. The control rods absorb neutrons to slow and control the chain reaction of the fission.

It has two stages of components-Primary stage and secondary stage or the second stage. The primary stage consists of the fission component and the secondary stage consists of the fusion component. The primary stage consists of High explosive lenses, tamper, uranium-238, levitation/vacuum, tritium gas, a hollow-core consisting of U-235 atoms. The secondary stage components of the fusion bomb consists of polystyrene foam, tamper, fusion fuel which consist of lithium-6 Deutreide, spark plug, and reflective casing. 

The uranium device is referred as the gun-type fission device, in which it fires a mass of uranium into another that produces a supercritical mass. 

The fusion reactor set will not be able to explode since it contains a plasma-like material to reduce and cool the temperature inside.

The lithium deuterium is used to store the isotopes of hydrogen since it doesn't decay at ambient temperatures. For the sustainability and durability of the device, the isotopes of hydrogen need to be at the active state constantly. 

Consequences and Incidents

When the bomb explodes, it starts from the primary stage, where the fission reaction occurs. The energy released from this stage transmits to the secondary stage as x-rays and radiation implosion occurs where the extremely high temperature is passed on to cause a fusion reaction. After the bomb explodes due to the extreme heat, a shock wave is produced and plenty of harmful radiation is released. It also caused a deafening sound, highly supersonic and these energy and shock waves can destroy the environment easily and can set on fire. The radiation produced will also affect the water and oxygen surrounded. These radiations might remain for a long time and can cause food posing, skin cancer and other health problems too. These radiations if emitted frequently can also cause climate change which will affect the earth. 

The H-bombs are limited and difficult to make as one mistake could cause havoc. Also, the making of this bomb is restricted in many places due to its great threat and consequences.

The Tsar bomb which is known to be an extremely powerful and dangerous type of H-bomb was exploded in Russia where it caused massive damage that a human could ever witness. North Koreas have also detonated H-bomb and they use this bomb as a nuclear weapon for their military protection. 

Context and Applications   

This topic is significant in the professional exams for both undergraduate and graduate courses, especially for 

• Bachelors in Science (Physics)
• Masters in Science (Physics)