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For years, nuclear fusion has been studied for civil and military applications. In the first case, as a source of clean and unlimited energy. On December 5, 2022, a group of researchers from the National Ignition Facility at the Lawrence Livermore National Laboratory carried out for the first time an inertial confinement fusion with a positive energy balance.
The 2.05 MJ supplied to the target in fact generated 3.15 MJ of power. However, 300 MJ of energy were needed to power the 192 lasers. The overall energy balance was therefore extremely negative. The research results were officially announced on December 13, 2022 in Washington.
In the last sixty years a considerable theoretical and experimental effort has also been made to develop nuclear fusion for civilian rather than war purposes, i.e. to generate electricity and also as a propulsion system for rockets, potentially much more efficient and with much lower environmental impact both of nuclear fission reactors, or of the centralized production of conventional energy mainly represented by thermoelectric and hydroelectric plants.
Nuclear fusion and applications as an energy source
The main problem from the 60s up to now, and probably also for the near future, is represented by the difficulty of achieving a positive energy balance of the reactor.
To date, in fact, it has not yet been possible to build a reactor which normally produces more electricity during its continuous operation than it consumes to feed the magnets and auxiliary systems. Once the positive energy balance has been reached, then, it will also be necessary to ensure a positive economic balance.
The main parameter that engineers use to evaluate the positive energy balance of a reactor is the Lawson parameter. At present, the most advanced fusion reactor is ITER. A thermonuclear fusion reactor, based on the tokamak-type configuration.
ITER is an international cooperative project between the European Union, Russia, China, Japan, the United States of America, South Korea and India. However, ITER is not yet the prototype of an electricity production plant but only an experimental machine intended to demonstrate that it can obtain the necessary energy gain conditions.
DEMO is instead the prototype of the plant being studied by the same participants in the ITER project. The SPARC project of Commonwealth Fusion Systems, of which Eni is the largest shareholder, aims to build an experimental fusion reactor that is more compact and cheaper than that of ITER.
In September 2021, a prototype was tested to demonstrate that it is possible to build a fusion chamber in which plasma confinement is ensured by high-temperature superconducting magnets.