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Heating, compressing and confining hydrogen plasmas at 100 million degrees is a significant challenge. It has taken a lot of science and engineering research to get fusion developments to where they are today.
Following the first fusion experiments in the 1930s, fusion physics laboratories were established around the world. By the mid-1950s, “fusion machines” were operating in the Soviet Union, the United Kingdom, the United States, France, Germany and Japan.
A major breakthrough occurred in 1968 in the Soviet Union, where researchers approached fusion conditions in a doughnut-shaped magnetic confinement device called a “tokamak” (from the Russian for “toroidal chamber with magnetic coils). From that time on, the tokamak was to become the dominant concept in fusion research, and tokamak devices multiplied across the globe (JET, TFTR, JT-60). Achievements in those machines led fusion science to an exciting threshold: the long sought-after energy “breakeven” point. Breakeven describes the moment when plasmas in a fusion device release at least as much energy as is required to produce them. Plasma energy breakeven has never been achieved, but scientists expect that the next-step tokamak device—ITER, currently under construction in France—will produce as much as 10 times more power than it consumes, beginning to write the chapter on 21st century fusion.
An alternative type of magnetic confinement device is the stellarator, which is shaped like a twisted doughnut. The world’s largest stellarator, called Wendelstein 7-X (or W7-X), is in Greifswald, Germany, operated by the Max Planck Institute for Plasma Physics. It began operation in 2015.
In parallel to magnetic fusion research, the international community is also exploring the feasibility of inertial confinement fusion as a viable energy source, where energetic beams such as lasers, are used to confine and heat the plasma to fusion conditions. This effort is being led by the experimental facility NIF currently under operation in California, USA. Although energy breakeven has not yet been achieved in the NIF, scientific and technological progress since start of operations in 2010 has been substantial, and ongoing experiments are expected to demonstrate a feasible path towards commercial fusion in the near term.
DID YOU KNOW?
In September 2013, scientists at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory achieved the first step towards harnessing the power of the sun here on earth – they got more energy out of a fuel burn than was put into it. Currently, NIF researchers are incorporating new diagnostics, adding new types of measurements that can show dynamics on a faster time scale, more accurately and with higher resolution in order to investigate “performance cliffs”–factors that limit performance.
The primary goal of the fusion program worldwide is the production of a commercially viable fusion power plant that will provide cheap, efficient, and clean power for the entire world. Fusion can also:
If scientists are successful in achieving a sustained fusion reactions, we will have an economical energy source that will change the world. Fusion fuel comes from water; it is widely available and easily harvested at low cost. One out of every 6,500 atoms of hydrogen in ordinary water is deuterium, giving a gallon of water the energy content of 300 gallons of gasoline.
Fusion Reactor History
Massachusetts Institute of Technology (MIT)
1991- Alcator C
1976 – PDX: Poloidal Divertor Experiment
1982-1997 TFTR: Tokamak Fusion Test Reactor
TFTR was the first in the world to use 50/50 mixtures of deuterium-tritium, yielding an unprecedented 10.7 million watts of fusion power.
In 2010 JT-60 was disassembled and is currently under construction to be upgraded to JT-60SA by using niobium-titanium superconducting coils.
The largest tokamak in the world, it is the only operational fusion experiment capable of producing fusion energy.
The NIF and ITER Projects
2018 – MIT scientists find a way to remove the excess heat from nuclear fusion reactors.
Center for Nuclear Science and Technology Information of the American Nuclear Society
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