World Largest Nuclear Fusion Experiment

Dr. S. S. VERMA; Department of Physics, S.L.I.E.T., Longowal; Distt.-Sangrur (Punjab)-148 106

2019-08-08 09:59:30



Fusion energy

Fusion is the energy source of the Sun and stars. In the tremendous heat and gravity at the core of these stellar bodies, hydrogen nuclei collide, fuse into heavier helium atoms and release tremendous amounts of energy in the process. It is no exaggeration to say that without fusion, there would be no life on Earth. Achieving controlled fusion reactions that net more power than they take to generate, and at commercial scale, is seen as a potential answer to climate change. Fusion energy would eliminate the need for fossil fuels and solve the intermittency and reliability concerns inherent with renewable energy sources. The energy would be generated without the dangerous amounts of radiation that raises concerns about fission nuclear energy. ITER, the world's largest tokamak, a magnetic fusion device that has been designed to prove the feasibility of fusion as a large-scale and carbon-free source of energy is based on the same principle that powers our Sun and stars. The experimental campaign that will be carried out at ITER is crucial to advancing fusion science and preparing the way for the fusion power plants of tomorrow.

Twentieth-century fusion science identified the most efficient fusion reaction in the laboratory setting to be the reaction between two hydrogen isotopes, deuterium (D) and tritium (T). The DT fusion reaction produces the highest energy gain at the "lowest" temperatures. Three conditions must be fulfilled to achieve fusion in a laboratory: very high temperature (on the order of 150,000,000° Celsius); sufficient plasma particle density (to increase the likelihood that collisions do occur); and sufficient confinement time (to hold the plasma, which has a propensity to expand, within a defined volume). At extreme temperatures, electrons are separated from nuclei and a gas becomes a plasma—often referred to as the fourth state of matter. Fusion plasmas provide the environment in which light elements can fuse and yield energy. In a tokamak device, powerful magnetic fields are used to confine and control the plasma.

Nuclear fusion experiment

The International Thermonuclear Experimental Reactor (ITER) project is an experiment aimed at reaching the next stage in the evolution of nuclear energy as a means of generating emissions-free electricity said to be world’s largest nuclear fusion experiment is set to launch operations in 2025. ITER  is one of the most ambitious energy projects in the world today. A multination project to build a fusion reactor cleared a milestone and is now 6 ½ years away from “First Plasma,” officials announced. Thirty-five nations are cooperating on the project to bring fusion power to the masses. International Thermonuclear Experimental Reactor is the second-most-expensive building in the world by total construction cost (25.00 billion US$). The construction site of ITER project is in southern France. The section recently installed—the cryostat base and lower cylinder—paves the way for the installation of the tokamak, the technology design chosen to house the powerful magnetic field that will encase the ultra-hot plasma fusion core. The ITER nuclear fusion reactor is poised to be the most complicated piece of machinery ever built. It will contain the world’s largest superconducting magnets, needed to generate a magnetic field powerful enough to contain a plasma that will reach temperatures of 150 million degrees Celsius, about 10 times hotter than the center of the sun.

ITER will be the first fusion device to produce net energy. ITER will be the first fusion device to maintain fusion for long periods of time. And ITER will be the first fusion device to test the integrated technologies, materials, and physics regimes necessary for the commercial production of fusion-based electricity. The amount of fusion energy a tokamak is capable of producing is a direct result of the number of fusion reactions taking place in its core. Scientists know that the larger the vessel, the larger the volume of the plasma ... and therefore the greater the potential for fusion energy. With ten times the plasma volume of the largest machine operating today, the ITER Tokamak will be a unique experimental tool, capable of longer plasmas and better confinement. The machine has been designed specifically to:

1) Produce 500 MW of fusion power

2) Demonstrate the integrated operation of technologies for a fusion power plant
3) Achieve a deuterium-tritium plasma in which the reaction is sustained through internal heating
4) Test tritium breeding

5) Demonstrate the safety characteristics of a fusion device


The tokamak is an experimental machine designed to harness the energy of fusion. ITER will be the world's largest tokamak, with a plasma radius (R) of 6.2 m and a plasma volume of 840 m³.

23000 Machine weight

150 million 0C plasma temperature

500MW fusion energy output

51GJ stored magnetic energy

4k magnet temperature

100000km Nb3Sn superconducting strand

8000 steel  plasma chamber

840m3 plasma volume

6.2m plasma major radius

440 blanket modules

736MW Maximum thermal load

180 design variants

Indian Contribution

ITER Members China, the European Union, India, Japan, Korea, Russia and the United States have entered into a 35-year collaboration to build and operate the ITER device. A two-decade research program is planned during which the Members will share in the experimental results and in any generated intellectual pusuit. Manufactured by India, the ITER cryostat is 16,000 cubic meters. Its diameter and height are both almost 30 meters and it weighs 3,850 tons. Because of its bulk, it is being fabricated in four main sections: the base, lower cylinder, upper cylinder, and top lid.  Different parts are being design at different places like: first major Tokamak components like the first PF Coil are from China,  a Vacuum Vessel sector from Korea and first TF coils (from Europe and Japan).

ITER Timeline

2005: Decision to site the project in France

2006: Signature of the ITER Agreement

2007: Formal creation of the ITER Organization

2007-2009: Land clearing and levelling

2010-2014: Ground support structure and seismic foundations for the Tokamak

2012: Nuclear licensing milestone: ITER becomes a Basic Nuclear Installation under French law

2014-2021: Construction of the Tokamak Building (access for assembly activities in 2019)

2010-2021: Construction of the ITER plant and auxiliary buildings for First Plasma

2008-2021: Manufacturing of principal First Plasma components

2015-2023: Largest components are transported along the ITER Itinerary

 2020-2025: Main assembly phase I

2022: Torus completion

2024: Cryostat closure

2024-2025: Integrated commissioning phase (commissioning by system starts several years earlier)

Dec 2025: First Plasma

2026: Begin installation of in-vessel components

2035: Deuterium-Tritium Operation begins