Beirut: British astrophysicist Arthur Eddington (1882-1942) did not know that when he suggested that nuclear fusion “would be an inexhaustible source of energy if mastered” that, for the first time in a hundred years after he said this, on 5 December, 2022, the US National Ignition Facility (NIF) would be able to generate more energy through this process than the energy consumed to produce it.
But why did the idea first come to the mind of an astrophysicist?
Because nuclear fusion is a process that occurs in the heart of stars, including our Sun, the centre of our eight-planet solar system. This 4.6 billion-year-old star fuses about 600 million tons of hydrogen per second and produces in the same second as much energy as humans consume in a full year (418 exajoules, according to the International Energy Agency; an exajoule is approximately equal to 278 terawatt-hours, and a terawatt-hour equals one trillion watt-hours).
Research in this field focuses on the integration of two isotopes of hydrogen, deuterium, and tritium. An isotope of any element is like the base element but has a different number of neutrons in its nucleus, while the atom of any element consists of a nucleus composed of protons and neutrons that are surrounded by electrons. On its part, hydrogen is the most available element in the universe.
The fusion results in a highly energetic neutron and helium atom. Helium is the next element of hydrogen in the periodic table, which arranges all the basic elements, starting with hydrogen.
But the laboratory process requires conditions that are not easy to achieve — including temperatures of up to a hundred million degrees Celsius, which require very large amounts of energy, and for any process to be feasible — and must emit more energy than it consumes to be initiated.
Developments and challenges
Nuclear fusion can be triggered by magnetic confinement, where highly powerful magnets confine hydrogen plasma — the nuclear fuel of the Sun that is formed only from protons after electrons have been separated from it by high heat — for very long periods of time, or by inertial confinement, which triggers the reaction with short, intense pulses and is more efficient than the former.
NIF, one of the few entities in the world that has the necessary equipment to create all these complex conditions, adopts the second type of confinement.
Until recently, no nuclear fusion experiment has been able to release more energy than it consumes, with the best figure of 65 per cent recorded in 1997 in the UK-based Joint European Torus (JET) using magnetic confinement. The latest test, at NIF, ended up with 150 per cent.