ITER is the world’s largest fusion experiment working to replicate fusion occurring in the Sun

  • ITER is the world’s largest fusion experiment working to replicate nuclear fusion occurring in the Sun.
  • Greenwald’s limit is the traditional law followed in fusion research correlating to fuel density.
  • With new experiments, scientists have realized that ITER can produce twice the energy due to possible modifications to fuel density limits.

 Over the years scientists have adhered to certain basic principles and laws of physics which were established nearly a century ago. However, with changing times and advancements in modern science, the question being asked is, “Do the old rules still apply?” While many avenues of science have done marvelously with them even to date, more upcoming fields such as nuclear fusion technology are setting precedents of their own. In simpler terms, newer branches of science are changing the traditional rules of the game.

What is ITER

ITER(International Thermonuclear Experimental Reactor) is international nuclear fusion research and engineering megaproject. It is the world’s largest fusion experiment and is aimed to replicate the fusion process which occurs in the Sun to produce energy.

A team of scientists, the Experts from the Swiss Federal Institute of Technology Lausanne (EPFL) recently published their research discussing the fundamental idea of plasma generation in the ITER. They believe that ITER can operate using twice the amount of hydrogen than what was believed to be its full capacity, meaning it could generate more amounts of nuclear fusion energy than previously estimated. This idea itself can change the rules of physics.

How does the ITER work

To understand the implications of the new research, one must understand the working principle of ITER. The ultimate goal here is to replicate nuclear fusion which occurs in the Sun. This fusion is a reaction in which two helium nuclei collide and combine into a single material and as a result, emit a large amount of utilizable energy.

One major requirement to stabilize such fusion reactions for energy production is high-temperature plasma. This plasma is an ionized matter similar to gaseous compounds and it contains both positively charged nuclei and negatively charged electrons. Plasmas could be artificially produced through fusion fuels or compounds of hydrogen atoms with very high temperatures that are almost ten times hotter than the sun’s core.

The process is carried out through a round, doughnut-shaped structure called the ‘tokamak.’ Tokamaks use strong electric and magnetic fields to manipulate and confine the plasma in the shape of a torus. Once the plasma is allowed to be in fitting conditions, fusion can be successfully carried out.

Raising the bar for nuclear fusion

The traditional approach to nuclear fusion research was contributed by the scientist Martin Greenwald. In 1988, Greenwald published a famous law correlating the fuel density with a tokamak’s minor radius as well as the current that flows in the plasma maintained in the tokamak. The law, named the “Greenwald limit”, became a foundational principle of research into nuclear fusion.

As suggested by their new research, published in Physical Review Letters, the EPFL group working with ITER has changed the rules. They believe Greenwald’s work was derived empirically and only based on experimental data. One of the major limitations was the correlation of fuel density in a tokamak.

Working with other international tokamak teams, the EPFL team designed a state-of-the-art experiment that allowed them to precisely measure the amount of fuel injected into a tokamak. The investigation was carried out at the world’s largest tokamaks housed in the UK and Germany and simulations were run through some of the largest computers in the world, including some from the CSCS, the Swiss National Supercomputing Center.

The net result is, that scientists found that as more plasma was added, thus increasing fuel density, parts of it moved from the outer cold layer of the tokamak, the boundary, back into its core, because this plasma becomes more turbulent. Thus plasma becomes more resistant as it cools. This means that the more fuel is added in at the same temperature, the more it cools down, thus making the flow of current in the plasma more difficult.

With these new formulations, the team wrote a new equation for the fuel limit in a tokamak. Crucially, the new equation purports that the Greenwald limit can be raised to almost double its current figure when it comes to the fuel used in ITER, meaning it can use almost double the fuel without disruption. Thus armed with its increased power capacity, ITER and other global tokamak projects aim to unleash the power of nuclear fusion, which has the potential to produce limitless energy for the world.


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