Context:

• Under its 'Artificial Sun' program, China successfully completed the construction and testing of the world's largest superconducting fusion magnet, weighing 582 tons.

Key Points:

• Event: Construction and testing of the world's largest superconducting fusion magnet.
• Weight and Size: Weight of 582 tons and length of 21 meters.
• Type of Magnet: Toroidal-field superconducting magnet.
• Developer Organization: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei.
• Associated Project/Reactor: BEST (Burning Plasma Experimental Superconducting Tokamak) – this is the next version of EAST (Experimental Advanced Superconducting Tokamak).
• Objective: To control and confine plasma at temperatures exceeding 100 million degrees Celsius (more than 6 times hotter than the core of the Sun).
• Target: To demonstrate electricity generation from controlled nuclear fusion by the year 2030.
• Shape and Dimensions: It is a 'D'-shaped toroidal-field magnet, with a length of 21 meters and a width of 12 meters. It is 13% larger in volume compared to the magnets built for the International Thermonuclear Experimental Reactor (ITER).
• ITER: 'International Thermonuclear Experimental Reactor' located in France (India is also a member country).
• Working Principle: It is designed to operate at an extremely low temperature of minus 269 degrees Celsius (near absolute zero) for 60 years and carry an electric current of more than 100,000 Amperes.
• Nuclear Fusion: The energy-generating process in the Sun and stars, in which light hydrogen atoms combine to form heavy helium atoms.
• Tokamak: A donut-shaped device that uses a magnetic field to control plasma.
• Superconductivity: A state of zero electrical resistance at extremely low temperatures, allowing massive electrical currents to flow without energy loss.

Nuclear Fusion:

• Definition: When two or more light nuclei combine under extremely high temperature and pressure to form a heavy nucleus, it is called nuclear fusion.
• Energy: This process releases several times more energy compared to nuclear fission.
• Equation (Example): Deuterium + Tritium → Helium + Neutron + Energy

Source of Energy in the Universe:

• Sun and Stars: Nuclear fusion is the primary source of energy in the Sun and other stars in the universe.
• Process: In the core of the Sun, hydrogen nuclei continuously fuse to form helium, releasing unlimited light and heat.

Hydrogen Bomb:

• Principle: The hydrogen bomb works entirely on the principle of Uncontrolled Nuclear Fusion.
• Invention: The hydrogen bomb was invented by Edward Teller in 1952.
• Lethality: It is thousands of times more powerful and destructive than an atomic bomb.
• Special Note: A temperature of 10 million Kelvin (extremely high) is required to initiate a fusion reaction. Therefore, a small atomic bomb (fission-based) is detonated first inside a hydrogen bomb to trigger the explosion.

Nuclear Fission:

• Definition: When a heavy nucleus is bombarded with neutrons, it splits into two or more lighter nuclei.
• Energy: This process releases a massive amount of energy along with a few new neutrons.
• Discovery: Discovered in 1938 by Otto Hahn and Fritz Strassmann.

Main Fuel:

• Uranium-235: The primary and naturally occurring fissionable fuel.
• Plutonium-239: A synthetic fuel prepared in reactors.

Chain Reaction:

• The neutrons released after fission split other nuclei, creating a 'chain'.

It is of two types:

• Controlled Chain Reaction: In this, the speed and number of neutrons are controlled, allowing energy to be generated in a controlled manner. This type of reaction is used in nuclear reactors for safe electricity generation.
• Uncontrolled Chain Reaction: In this, there is no control over the number and speed of neutrons, causing the reaction to spread extremely fast and result in a massive explosion with huge amounts of energy. This type of reaction is used in atomic bombs.

Main Components of a Nuclear Reactor:

• The main components of a nuclear reactor include Fuel, Moderator, Control Rods, and Coolant.
• Uranium-235 or Plutonium-239 is generally used as fuel.
• The moderator slows down the speed of neutrons to sustain the chain reaction, for which Heavy Water and Graphite are used.
• Control rods absorb extra neutrons to keep the reaction controlled; these are generally made of Cadmium or Boron.
• The coolant absorbs the generated heat and transfers it to the turbine; Ordinary Water, Heavy Water, or Liquid Sodium are used for this purpose.
• First Nuclear Reactor: Built in 1942 under the leadership of Enrico Fermi in Chicago.
• Principle of Atomic Bomb: Completely based on uncontrolled nuclear fission.
• First Atomic Bomb: Built under the 'Manhattan Project', whose father was J. Robert Oppenheimer.
• Source of Energy: Energy in fission is released due to mass defect, following Einstein's famous mass-energy equation.
• India's First Nuclear Reactor: Apsara, which was established in 1956 at Trombay (Mumbai).

Nuclear Fission vs. Nuclear Fusion: